Convective heat transfer measurements in a vapour-liquid-liquid three-phase direct contact heat exchanger

NASA Astrophysics Data System (ADS)

Mahood, Hameed B.; Campbell, A. N.; Baqir, Ali Sh.; Sharif, A. O.; Thorpe, R. B.

2017-12-01

Energy usage is increasing around the world due to the continued development of technology, and population growth. Solar energy is a promising low-grade energy resource that can be harvested and utilised in different applications, such solar heater systems, which are used in both domestic and industrial settings. However, the implementation of an efficient energy conversion system or heat exchanger would enhance such low-grade energy processes. The direct contact heat exchanger could be the right choice due to its ability to efficiently transfer significant amounts of heat, simple design, and low cost. In this work, the heat transfer associated with the direct contact condensation of pentane vapour bubbles in a three-phase direct contact condenser is investigated experimentally. Such a condenser could be used in a cycle with a solar water heater and heat recovery systems. The experiments on the steady state operation of the three-phase direct contact condenser were carried out using a short Perspex tube of 70 cm in total height and an internal diameter of 4 cm. Only a height of 48 cm was active as the direct contact condenser. Pentane vapour, (the dispersed phase) with three different initial temperatures (40° C, 43.5° C and 47.5° C) was directly contacted with water (the continuous phase) at 19° C. The experimental results showed that the total heat transfer rate per unit volume along the direct contact condenser gradually decreased upon moving higher up the condenser. Additionally, the heat transfer rate increases with increasing mass flow rate ratio, but no significant effect on the heat transfer rate of varying the initial temperature of the dispersed phase was seen. Furthermore, both the outlet temperature of the continuous phase and the void fraction were positively correlated with the total heat transfer rate per unit volume, with no considerable effect of the initial temperature difference between the dispersed and continuous phases.

The Thermoregulatory Consequences of Heat Stroke: Are Cytokines Involved

DTIC Science & Technology

2006-01-01

71 6. Ambient temperature effects on heat stroke outcome ... exposure , the effectiveness of this treatment following administration directly into the hy- pothalamus was not tested (Lin et al., 1994). In addition, it is...versus that of heat exposure on experimental outcome (i.e., mortality). However, ethical concerns regarding the use of mortality as a study endpoint

Article and method of forming an article

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lacy, Benjamin Paul; Kottilingam, Srikanth Chandrudu; Dutta, Sandip

Provided are an article and a method of forming an article. The method includes providing a metallic powder, heating the metallic powder to a temperature sufficient to joint at least a portion of the metallic powder to form an initial layer, sequentially forming additional layers in a build direction by providing a distributed layer of the metallic powder over the initial layer and heating the distributed layer of the metallic powder, repeating the steps of sequentially forming the additional layers in the build direction to form a portion of the article having a hollow space formed in the build direction,more » and forming an overhang feature extending into the hollow space. The article includes an article formed by the method described herein.« less

Redesign of the Human Metabolic Simulator

NASA Technical Reports Server (NTRS)

Duffield, Bruce; Jeng, Frank; Lange, Kevin

2004-01-01

The National Aeronautics and Space Administration (NASA) is currently building a Human Metabolic Simulator (HMS) at the Johnson Space Center as part of the Advanced Life Support Air Revitalization Technology Evaluation Facility (ARTEF). The purpose of ARTEF is to evaluate Environmental Control and Life Support System Technologies for Advanced Missions. The HMS is needed to reproduce the primary metabolic effects of human respiration on an enclosed atmosphere when humans cannot be present and the impact of human presence on the system is required. A HMS was designed, built and successfully operated in 2000 but larger crew size requirements and the expense of upgrade of the current system necessitate redesign. This paper addresses the redesign. Several concepts were considered, ranging from chemical oxidation of a hydrocarbon like ethanol or ethyl acetate to carbon dioxide and water, oxidation of an iron-containing compound, or by using a fuel cell. For reasons of cost, simplicity, safety and other factors, the concept chosen includes: a molecular sieve packaged as an industrial oxygen concentrator to remove oxygen from the atmosphere, with direct carbon dioxide, water and heat injection. The water injection is done via heating water to steam with a heat exchanger and thermal effects are handled by directly adding heat to the air stream with a second heat exchanger. Both heat exchangers are supplied by a hot oil loop. The amount of oxygen removal, carbon dioxide addition, water addition and heat addition were calculated using metabolic profiles for respiration and heat, calculated using a series of empirical equations developed for International Space Station (ISS). Sketches of the Human Metabolic Simulator and the hot oil bath loop used to supply heat to the heat exchangers are included

Metal Hydride Heat Storage Technology for Directed Energy Weapon Systems

DTIC Science & Technology

2007-11-16

high thermal conductivity materials for heat transfer enhancement. In addition, the PCMs ’ low heat storage density requires excessively large system...capacity as compared to the PCMs . For example, Ca0.2M0.8Ni5, a commercial hydride, has a heat storage density of 853.3MJ/m³ in raw material condition...Huston and Sandrock, 1980], while paraffin (Calwax 130), a common organic PCM has a heat storage capacity of 177.5MJ/m³ [Al-Hallaj and Selman, 2000]. The

Thin Film Heat Flux Sensors: Design and Methodology

NASA Technical Reports Server (NTRS)

Fralick, Gustave C.; Wrbanek, John D.

2013-01-01

Thin Film Heat Flux Sensors: Design and Methodology: (1) Heat flux is one of a number of parameters, together with pressure, temperature, flow, etc. of interest to engine designers and fluid dynamists, (2) The measurement of heat flux is of interest in directly determining the cooling requirements of hot section blades and vanes, and (3)In addition, if the surface and gas temperatures are known, the measurement of heat flux provides a value for the convective heat transfer coefficient that can be compared with the value provided by CFD codes.

Thermoelectric Power Generation System for Future Hybrid Vehicles Using Hot Exhaust Gas

NASA Astrophysics Data System (ADS)

Kim, Sun-Kook; Won, Byeong-Cheol; Rhi, Seok-Ho; Kim, Shi-Ho; Yoo, Jeong-Ho; Jang, Ju-Chan

2011-05-01

The present experimental and computational study investigates a new exhaust gas waste heat recovery system for hybrid vehicles, using a thermoelectric module (TEM) and heat pipes to produce electric power. It proposes a new thermoelectric generation (TEG) system, working with heat pipes to produce electricity from a limited hot surface area. The current TEG system is directly connected to the exhaust pipe, and the amount of electricity generated by the TEMs is directly proportional to their heated area. Current exhaust pipes fail to offer a sufficiently large hot surface area for the high-efficiency waste heat recovery required. To overcome this, a new TEG system has been designed to have an enlarged hot surface area by the addition of ten heat pipes, which act as highly efficient heat transfer devices and can transmit the heat to many TEMs. As designed, this new waste heat recovery system produces a maximum 350 W when the hot exhaust gas heats the evaporator surface of the heat pipe to 170°C; this promises great possibilities for application of this technology in future energy-efficient hybrid vehicles.

Low-cost fabrication and direct bond installation of flat, single-curvature and compound-curvature ablative heat shield panels

NASA Technical Reports Server (NTRS)

Norwood, L. B.

1972-01-01

Procedures for low cost fabrication and direct bond installation of flat, single curved, and compound curvature ablative heat shields on a DC-3 aircraft are discussed. The panel sizes and attachment locations are identified. In addition to the bonding of the four contoured panels, two flat panels were bonded to the nearly flat, lower surface of the center wing section. The detailed requirements and objectives of the investigation are described.

Data related to cyclic deformation and fatigue behavior of direct laser deposited Ti-6Al-4V with and without heat treatment.

PubMed

Sterling, Amanda J; Torries, Brian; Shamsaei, Nima; Thompson, Scott M

2016-03-01

Data is presented describing the strain-controlled, fully-reversed uniaxial cyclic deformation and fatigue behavior of Ti-6Al-4V specimens additively manufactured via Laser Engineered Net Shaping (LENS) - a Direct Laser Deposition (DLD) process. The data was collected by performing multiple fatigue tests on specimens with various microstructural states/conditions, i.e. in their 'as-built', annealed (below the beta transus temperature), or heat treated (above the beta transus temperature) condition. Such data aids in characterizing the mechanical integrity and fatigue resistance of DLD parts. Data presented herein also allows for elucidating the strong microstructure coupling of the fatigue behavior of DLD Ti-6Al-4V, as the data trends were found to vary with material condition (i.e. as-built, annealed or heat treated) [1]. This data is of interest to the additive manufacturing and fatigue scientific communities, as well as the aerospace and biomedical industries, since additively-manufactured parts cannot be reliably deployed for public use, until their mechanical properties are understood with high certainty.

Data related to cyclic deformation and fatigue behavior of direct laser deposited Ti–6Al–4V with and without heat treatment

PubMed Central

Sterling, Amanda J.; Torries, Brian; Shamsaei, Nima; Thompson, Scott M.

2016-01-01

Data is presented describing the strain-controlled, fully-reversed uniaxial cyclic deformation and fatigue behavior of Ti–6Al–4V specimens additively manufactured via Laser Engineered Net Shaping (LENS) – a Direct Laser Deposition (DLD) process. The data was collected by performing multiple fatigue tests on specimens with various microstructural states/conditions, i.e. in their ‘as-built’, annealed (below the beta transus temperature), or heat treated (above the beta transus temperature) condition. Such data aids in characterizing the mechanical integrity and fatigue resistance of DLD parts. Data presented herein also allows for elucidating the strong microstructure coupling of the fatigue behavior of DLD Ti–6Al–4V, as the data trends were found to vary with material condition (i.e. as-built, annealed or heat treated) [1]. This data is of interest to the additive manufacturing and fatigue scientific communities, as well as the aerospace and biomedical industries, since additively-manufactured parts cannot be reliably deployed for public use, until their mechanical properties are understood with high certainty. PMID:26949728

75 FR 24389 - Airworthiness Directives; Bombardier, Inc. Model DHC-8-400 Series Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-05

... concern. * * * * * Loss of both AC generators could lead to unannunciated loss of heat to both engine... protruding stems which chafed through the wire insulation leading to arcing damage. In addition, the wire... shroud. Loss of both AC generators could lead to unannunciated loss of heat to both engine inlets, which...

Passive solar nursing home for Northern Kentucky

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taylor, J.G.; Ward, J.D.

This project is a 32-bed nursing home designed as an addition to an existing facility. Passive solar strategies included direct gain room windows and clerestories which admit light to phase change salt pouches in the ceilings of patient rooms. Corridors are skykighted; and the heating, ventilating, and conditioning system is comprised of water-source heat pumps and a 5000 gallon storage tank in conjunction with an air to air heat recovery wheel.

Decontamination of drinking water by direct heating in solar panels.

PubMed

Fjendbo Jørgensen, A J; Nøhr, K; Sørensen, H; Boisen, F

1998-09-01

A device was developed for direct heating of water by solar radiation in a flow-through system of copper pipes. An adjustable thermostat valve prevents water below the chosen temperature from being withdrawn. The results show that it is possible to eliminate coliform and thermotolerant coliform bacteria from naturally contaminated river water by heating to temperatures of 65 degrees C or above. Artificial additions of Salmonella typhimurium, Streptococcus faecalis and Escherichia coli to contaminated river water were also inactivated after heating to 65 degrees C and above. The total viable count could be reduced by a factor of 1000. The heat-resistant bacteria isolated from the Mlalakuva River (Tanzania) were spore-forming bacteria which exhibited greater heat resistance than commonly used test bacteria originating from countries with colder climates. To provide a good safety margin it is recommended that an outlet water temperature of 75 degrees C be used. At that temperature the daily production was about 501 of decontaminated water per m2 of solar panel, an amount that could be doubled by using a heat exchanger to recycle the heat.

Fabrication of Thermoelectric Devices Using Additive-Subtractive Manufacturing Techniques: Application to Waste-Heat Energy Harvesting

NASA Astrophysics Data System (ADS)

Tewolde, Mahder

Thermoelectric generators (TEGs) are solid-state devices that convert heat directly into electricity. They are well suited for waste-heat energy harvesting applications as opposed to primary energy generation. Commercially available thermoelectric modules are flat, inflexible and have limited sizes available. State-of-art manufacturing of TEG devices relies on assembling prefabricated parts with soldering, epoxy bonding, and mechanical clamping. Furthermore, efforts to incorporate them onto curved surfaces such as exhaust pipes, pump housings, steam lines, mixing containers, reaction chambers, etc. require custom-built heat exchangers. This is costly and labor-intensive, in addition to presenting challenges in terms of space, thermal coupling, added weight and long-term reliability. Additive manufacturing technologies are beginning to address many of these issues by reducing part count in complex designs and the elimination of sub-assembly requirements. This work investigates the feasibility of utilizing such novel manufacturing routes for improving the manufacturing process of thermoelectric devices. Much of the research in thermoelectricity is primarily focused on improving thermoelectric material properties by developing of novel materials or finding ways to improve existing ones. Secondary to material development is improving the manufacturing process of TEGs to provide significant cost benefits. To improve the device fabrication process, this work explores additive manufacturing technologies to provide an integrated and scalable approach for TE device manufacturing directly onto engineering component surfaces. Additive manufacturing techniques like thermal spray and ink-dispenser printing are developed with the aim of improving the manufacturing process of TEGs. Subtractive manufacturing techniques like laser micromachining are also studied in detail. This includes the laser processing parameters for cutting the thermal spray materials efficiently by optimizing cutting speed and power while maintaining surface quality and interface properties. Key parameters are obtained from these experiments and used to develop a process that can be used to fabricate a working TEG directly onto the waste-heat component surface. A TEG module has been fabricated for the first time entirely by using thermal spray technology and laser micromachining. The target applications include automotive exhaust systems and other high-volume industrial waste heat sources. The application of TEGs for thermoelectrically powered sensors for Small Modular Reactors (SMRs) is presented. In conclusion, more ways to improve the fabrication process of TEGs are suggested.

Overview of Heat Addition and Efficiency Predictions for an Advanced Stirling Convertor

NASA Technical Reports Server (NTRS)

Wilson, Scott D.; Reid, Terry; Schifer, Nicholas; Briggs, Maxwell

2011-01-01

Past methods of predicting net heat input needed to be validated. Validation effort pursued with several paths including improving model inputs, using test hardware to provide validation data, and validating high fidelity models. Validation test hardware provided direct measurement of net heat input for comparison to predicted values. Predicted value of net heat input was 1.7 percent less than measured value and initial calculations of measurement uncertainty were 2.1 percent (under review). Lessons learned during validation effort were incorporated into convertor modeling approach which improved predictions of convertor efficiency.

Laboratory Simulation of the Geothermal Heating Effects on Ocean Overturning Circulation

NASA Astrophysics Data System (ADS)

Xia, K. Q.; Wang, F.; Huang, S. D.; Zhou, S. Q.

2016-12-01

A large-scale circulation subject to an additional heat flux from the bottom is investigated laboratorially, motivated by understanding the geothermal heating effects on ocean circulation. Despite its idealization, our experiment suggests that the leading order effect of geothermal heating is to significantly enhance the abyssal overturning, which is in agreement with the findings in ocean circulation models. Our results also suggest that geothermal heating could not influence the poleward heat transport due to the strong stratification in the thermocline. It is revealed that the ratio of geothermal-flux-induced turbulent dissipation to the dissipation due to other energies is the key determining the dynamical importance of geothermal heating. This quantity explains why the impact of geothermal heating is sensitive to the deep stratification and the diapycnal mixing, in addition to the amount of geothermal flux. Moreover, this dissipation ratio may be used to understand results from different studies in a consistent way. This work is supported by the Hong Kong Research Grants Council under Grant No. CUHK1430115 and by the CUHK Research Committee through a Direct Grant (Project No. 3132740).

Potentialities of TEC topping: A simplified view of parametric effects

NASA Technical Reports Server (NTRS)

Morris, J. F.

1980-01-01

An examination of the benefits of thermionic-energy-conversion (TEC)-topped power plants and methods of increasing conversion efficiency are discussed. Reductions in the cost of TEC modules yield direct decreases in the cost of electricity (COE) from TEC-topped central station power plants. Simplified COE, overall-efficiency charts presented illustrate this trend. Additional capital-cost diminution results from designing more compact furnaces with considerably increased heat transfer rates allowable and desirable for high temperature TEC and heat pipes. Such improvements can evolve of the protection from hot corrosion and slag as well as the thermal expansion compatibilities offered by silicon-carbide clads on TEC-heating surfaces. Greater efficiencies and far fewer modules are possible with high-temperature, high-power-density TEC: This decreases capital and fuel costs much more and substantially increases electric power outputs for fixed fuel inputs. In addition to more electricity, less pollution, and lower costs, TEC topping used directly in coal-combustion products contributes balance-of-payment gains.

Fabrication and Testing of a Thin-Film Heat Flux Sensor for a Stirling Convertor

NASA Technical Reports Server (NTRS)

Wilson, Scott D.; Fralick, Gustave; Wrbanek, John; Sayir, Ali

2009-01-01

The NASA Glenn Research Center (GRC) has been testing high efficiency free-piston Stirling convertors for potential use in radioisotope power systems since 1999. Stirling convertors are being operated for many years to demonstrate a radioisotope power system capable of providing reliable power for potential multi-year missions. Techniques used to monitor the convertors for change in performance include measurements of temperature, pressure, energy addition, and energy rejection. Micro-porous bulk insulation is used in the Stirling convertor test set up to minimize the loss of thermal energy from the electric heat source to the environment. The insulation is characterized before extended operation, enabling correlation of the net thermal energy addition to the convertor. Aging microporous bulk insulation changes insulation efficiency, introducing errors in the correlation for net thermal energy addition. A thin-mm heat flux sensor was designed and fabricated to directly measure the net thermal energy addition to the Stirling convertor. The fabrication techniques include slip casting and using Physical Vapor Deposition (PVD). One micron thick noble metal thermocouples measure temperature on the surface of an Alumina ceramic disc and heat flux is calculated. Fabrication, integration, and test results of a thin film heat flux sensor are presented.

Fabrication and Testing of a Thin-Film Heat Flux Sensor for a Stirling Convertor

NASA Technical Reports Server (NTRS)

Wilson, Scott D.; Fralick, Gus c.; Wrbanek, John D.; Sayir, Ali

2010-01-01

The NASA Glenn Research Center (GRC) has been testing high-efficiency free-piston Stirling convertors for potential use in radioisotope power systems since 1999. Stirling convertors are being operated for many years to demonstrate a radioisotope power system capable of providing reliable power for potential multiyear missions. Techniques used to monitor the convertors for change in performance include measurements of temperature, pressure, energy addition, and energy rejection. Micro-porous bulk insulation is used in the Stirling convertor test setup to minimize the loss of thermal energy from the electric heat source to the environment. The insulation is characterized before extended operation, enabling correlation of the net thermal energy addition to the convertor. Aging micro-porous bulk insulation changes insulation efficiency, introducing errors in the correlation for net thermal energy addition. A thin-film heat flux sensor was designed and fabricated to directly measure the net thermal energy addition to the Stirling convertor. The fabrication techniques include slipcasting and using Physical Vapor Deposition (PVD). One-micron-thick noble metal thermocouples measure temperature on the surface of an alumina ceramic disk and heat flux is calculated. Fabrication, integration, and test results of a thin-film heat flux sensor are presented.

Solid-gas phase equilibria and thermodynamic properties of cadmium selenide.

NASA Technical Reports Server (NTRS)

Sigai, A. G.; Wiedemeier, H.

1972-01-01

Accurate vapor pressures are determined through direct weight loss measurements using the Knudsen effusion technique. The experimental data are evaluated by establishing the mode of vaporization and determining the heat capacity of cadmium selenide at elevated temperatures. Additional information is obtained through a second- and third-law evaluation of data, namely, the heat of formation and the absolute entropy of cadmium selenide. A preferential loss of selenium during the initial heating of CdSe is observed, which leads to a deviation in stoichiometry.

Plasma heating for containerless and microgravity materials processing

NASA Technical Reports Server (NTRS)

Leung, Emily W. (Inventor); Man, Kin F. (Inventor)

1994-01-01

A method for plasma heating of levitated samples to be used in containerless microgravity processing is disclosed. A sample is levitated by electrostatic, electromagnetic, aerodynamic, or acoustic systems, as is appropriate for the physical properties of the particular sample. The sample is heated by a plasma torch at atmospheric pressure. A ground plate is provided to help direct the plasma towards the sample. In addition, Helmholtz coils are provided to produce a magnetic field that can be used to spiral the plasma around the sample. The plasma heating system is oriented such that it does not interfere with the levitation system.

Heat Transfer Measurements on Surfaces with Natural Ice Castings and Modeled Roughness

NASA Technical Reports Server (NTRS)

Breuer, Kenneth S.; Torres, Benjamin E.; Orr, D. J.; Hansman, R. John

1997-01-01

An experimental method is described to measure and compare the convective heat transfer coefficient of natural and simulated ice accretion roughness and to provide a rational means for determining accretion-related enhanced heat transfer coefficients. The natural ice accretion roughness was a sample casting made from accretions at the NASA Lewis Icing Research Tunnel (IRT). One of these castings was modeled using a Spectral Estimation Technique (SET) to produce three roughness elements patterns that simulate the actual accretion. All four samples were tested in a flat-plate boundary layer at angle of attack in a "dry" wind tunnel test. The convective heat transfer coefficient was measured using infrared thermography. It is shown that, dispite some problems in the current data set, the method does show considerable promise in determining roughness-induced heat transfer coefficients, and that, in addition to the roughness height and spacing in the flow direction, the concentration and spacing of elements in the spanwise direction are important parameters.

Switching of the Spin-Density-Wave in CeCoIn5 probed by Thermal Conductivity

NASA Astrophysics Data System (ADS)

Kim, Duk Y.; Lin, Shi-Zeng; Weickert, Franziska; Bauer, Eric D.; Ronning, Filip; Thompson, Joe D.; Movshovich, Roman

Unconventional superconductor CeCoIn5 orders magnetically in a spin-density-wave (SDW) in the low-temperature and high-field corner of the superconducting phase. Recent neutron scattering experiment revealed that the single-domain SDW's ordering vector Q depends strongly on the direction of the magnetic field, switching sharply as the field is rotated through the anti-nodal direction. This switching may be manifestation of a pair-density-wave (PDW) p-wave order parameter, which develops in addition to the well-established d-wave order parameter due to the SDW formation. We have investigated the hypersensitivity of the magnetic domain with a thermal conductivity measurement. The heat current (J) was applied along the [110] direction such that the Q vector is either perpendicular or parallel to J, depending on the magnetic field direction. A discontinuous change of the thermal conductivity was observed when the magnetic field is rotated around the [100] direction within 0 . 2° . The thermal conductivity with the Q parallel to the heat current (J ∥Q) is approximately 15% lager than that with the Q perpendicular to the heat current (J ⊥Q). This result is consistent with additional gapping of the nodal quasiparticle by the p-wave PDW coupled to SDW. Work at Los Alamos was performed under the auspices of the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering.

Regeneratively Cooled Porous Media Jacket

NASA Technical Reports Server (NTRS)

Mungas, Greg (Inventor); Fisher, David J. (Inventor); London, Adam Pollok (Inventor); Fryer, Jack Merrill (Inventor)

2013-01-01

The fluid and heat transfer theory for regenerative cooling of a rocket combustion chamber with a porous media coolant jacket is presented. This model is used to design a regeneratively cooled rocket or other high temperature engine cooling jacket. Cooling jackets comprising impermeable inner and outer walls, and porous media channels are disclosed. Also disclosed are porous media coolant jackets with additional structures designed to transfer heat directly from the inner wall to the outer wall, and structures designed to direct movement of the coolant fluid from the inner wall to the outer wall. Methods of making such jackets are also disclosed.

Improved momentum-transfer theory for ion mobility. 1. Derivation of the fundamental equation.

PubMed

Siems, William F; Viehland, Larry A; Hill, Herbert H

2012-11-20

For the first time the fundamental ion mobility equation is derived by a bottom-up procedure, with N real atomic ion-atomic neutral collisions replaced by N repetitions of an average collision. Ion drift velocity is identified as the average of all pre- and postcollision velocities in the field direction. To facilitate velocity averaging, collisions are sorted into classes that "cool" and "heat" the ion. Averaging over scattering angles establishes mass-dependent relationships between pre- and postcollision velocities for the cooling and heating classes, and a combined expression for drift velocity is obtained by weighted addition according to relative frequencies of the cooling and heating encounters. At zero field this expression becomes identical to the fundamental low-field ion mobility equation. The bottom-up derivation identifies the low-field drift velocity as 3/4 of the average precollision ion velocity in the field direction and associates the passage from low-field to high-field conditions with the increasing dominance of "cooling" collisions over "heating" collisions. Most significantly, the analysis provides a direct path for generalization to fields of arbitrary strength.

Electromagnetic induction heating for single crystal graphene growth: morphology control by rapid heating and quenching

NASA Astrophysics Data System (ADS)

Wu, Chaoxing; Li, Fushan; Chen, Wei; Veeramalai, Chandrasekar Perumal; Ooi, Poh Choon; Guo, Tailiang

2015-03-01

The direct observation of single crystal graphene growth and its shape evolution is of fundamental importance to the understanding of graphene growth physicochemical mechanisms and the achievement of wafer-scale single crystalline graphene. Here we demonstrate the controlled formation of single crystal graphene with varying shapes, and directly observe the shape evolution of single crystal graphene by developing a localized-heating and rapid-quenching chemical vapor deposition (CVD) system based on electromagnetic induction heating. Importantly, rational control of circular, hexagonal, and dendritic single crystalline graphene domains can be readily obtained for the first time by changing the growth condition. Systematic studies suggest that the graphene nucleation only occurs during the initial stage, while the domain density is independent of the growth temperatures due to the surface-limiting effect. In addition, the direct observation of graphene domain shape evolution is employed for the identification of competing growth mechanisms including diffusion-limited, attachment-limited, and detachment-limited processes. Our study not only provides a novel method for morphology-controlled graphene synthesis, but also offers fundamental insights into the kinetics of single crystal graphene growth.

Without Warning: Worker Deaths From Heat 2014-2016.

PubMed

Roelofs, Cora

2018-01-01

Worker deaths from heat exposure are unlike heat deaths in the general population; workers tend to be outside in variable temperatures and younger than sixty-five years. Climate change will increase the frequency, duration, and variability of hot temperatures. Public health warning systems, such as the Heat Index of the National Weather Service, do not generally account for workers' greater likelihood of exposure to direct sunlight or exertion. Only 28% of the 79 worker heat-related fatalities during 2014-2016 occurred on days when the National Weather Service warning would have included the possibility of fatal heat stroke. Common heat illness prevention advice ignores workers' lack of control over their ability to rest and seek cooler temperatures. Additionally, acclimatization, or phased-in work in the heat, may be less useful given temperature variability under climate change. Workers' vulnerability and context of heat exposure should inform public health surveillance and response to prevent heat illness and death.

Thermal energy storage for solar power generation - State of the art

NASA Astrophysics Data System (ADS)

Shukla, K. N.

1981-12-01

High temperature storage for applications in solar-thermal electric systems is considered. Noting that thermal storage is in either the form of latent, sensible or chemically stored heat, sensible heat storage is stressed as the most developed of the thermal storage technologies, spanning direct heating of a storage medium from 120-1250 C. Current methods involve solids, packed beds, fluidized beds, liquids, hot water, organic liquids, and inorganic liquids and molten salts. Latent heat storage comprises phase-change materials that move from solid to liquid with addition of heat and liquid to solid with the removal of heat. Metals or inorganic salts are candidates, and the energy balances are outlined. Finally, chemical heat storage is examined, showing possible high energy densities through catalytic, thermal dissociation reactions.

A Comprehensive Study of a Micro-Channel Heat Sink Using Integrated Thin-Film Temperature Sensors

PubMed Central

Wang, Tao; Wang, Jiejun; He, Jian; Wu, Chuangui; Luo, Wenbo; Shuai, Yao; Zhang, Wanli; Chen, Xiancai; Zhang, Jian; Lin, Jia

2018-01-01

A micro-channel heat sink is a promising cooling method for high power integrated circuits (IC). However, the understanding of such a micro-channel device is not sufficient, because the tools for studying it are very limited. The details inside the micro-channels are not readily available. In this letter, a micro-channel heat sink is comprehensively studied using the integrated temperature sensors. The highly sensitive thin film temperature sensors can accurately monitor the temperature change in the micro-channel in real time. The outstanding heat dissipation performance of the micro-channel heat sink is proven in terms of maximum temperature, cooling speed and heat resistance. The temperature profile along the micro-channel is extracted, and even small temperature perturbations can be detected. The heat source formed temperature peak shifts towards the flow direction with the increasing flow rate. However, the temperature non-uniformity is independent of flow rate, but solely dependent on the heating power. Specific designs for minimizing the temperature non-uniformity are necessary. In addition, the experimental results from the integrated temperature sensors match the simulation results well. This can be used to directly verify the modeling results, helping to build a convincing simulation model. The integrated sensor could be a powerful tool for studying the micro-channel based heat sink. PMID:29351248

A Comprehensive Study of a Micro-Channel Heat Sink Using Integrated Thin-Film Temperature Sensors.

PubMed

Wang, Tao; Wang, Jiejun; He, Jian; Wu, Chuangui; Luo, Wenbo; Shuai, Yao; Zhang, Wanli; Chen, Xiancai; Zhang, Jian; Lin, Jia

2018-01-19

A micro-channel heat sink is a promising cooling method for high power integrated circuits (IC). However, the understanding of such a micro-channel device is not sufficient, because the tools for studying it are very limited. The details inside the micro-channels are not readily available. In this letter, a micro-channel heat sink is comprehensively studied using the integrated temperature sensors. The highly sensitive thin film temperature sensors can accurately monitor the temperature change in the micro-channel in real time. The outstanding heat dissipation performance of the micro-channel heat sink is proven in terms of maximum temperature, cooling speed and heat resistance. The temperature profile along the micro-channel is extracted, and even small temperature perturbations can be detected. The heat source formed temperature peak shifts towards the flow direction with the increasing flow rate. However, the temperature non-uniformity is independent of flow rate, but solely dependent on the heating power. Specific designs for minimizing the temperature non-uniformity are necessary. In addition, the experimental results from the integrated temperature sensors match the simulation results well. This can be used to directly verify the modeling results, helping to build a convincing simulation model. The integrated sensor could be a powerful tool for studying the micro-channel based heat sink.

Investigation of the thermal hazardous effect of protective clothing caused by stored energy discharge.

PubMed

He, Jiazhen; Lu, Yehu; Chen, Yan; Li, Jun

2017-09-15

In addition to direct thermal energy from a heating source, a large amount of thermal energy stored in clothing will continuously discharge to skin after exposure. Investigating the thermal hazardous effect of clothing caused by stored energy discharge is crucial for the reliability of thermal protective clothing. In this study several indices were proposed and applied to evaluate the impact of thermal energy discharge on human skin. The heat discharge from different layers of fabric systems was investigated, and the influences of air gaps and applied compression were examined. Heat fluxes at the boundaries of fabric layers and the distribution of heat discharge were determined. Additionally, the correlation between heat storage during exposure and heat discharge after exposure was identified. The results demonstrated that heat discharge to the skin could be correlated with heat storage within the fabric, however, it highly depended on the air gap under clothing, the applied compression, and the insulation provided by the fabric layers. Results from this study could contribute to thoroughly understanding the thermal hazardous effect of clothing and enhance the technical basis for developing new fabric combinations to minimize energy discharge after exposure. Copyright © 2017 Elsevier B.V. All rights reserved.

Heat injury and recovery of Streptococcus faecium associated with the souring of chub-packed luncheon meat.

PubMed

Bell, R G; De Lacy, K M

1984-10-01

The presence of NaCl in the heating medium provided some protection from lethal heat damage for cells of a Streptococcus faecium strain isolated from luncheon meat whereas the presence of NaNO2 either alone or in addition to NaCl, had no significant effect on cell survival. Subsequent recovery and growth of heat-damaged cells was retarded by the presence of NaCl. When NaNO2 was present in addition to NaCl the inhibitory effect of the latter was reduced. These principal components of the luncheon-meat-cure are apparently opposed in their activities on post-heating recovery and growth of Strep. faecium. Product stability, i.e. duration of the lag before growth occurs, is directly related to the severity of the heat treatment and to the concentration of NaCl in the product. Therefore the resistance of pasteurized chub-packed luncheon meat to streptococcal spoilage during storage at temperatures conducive to microbial growth results from a prolonged heat-induced salt-maintained pre-growth adjustment phase rather than to any inherent inhibitory property of the luncheon meat to the growth of non-heat-damaged Strep. faecium cells.

Pahoa geothermal industrial park. Engineering and economic analysis for direct applications of geothermal energy in an industrial park at Pahoa, Hawaii

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moreau, J.W.

1980-12-01

This engineering and economic study evaluated the potential for developing a geothermal industrial park in the Puna District near Pahoa on the Island of Hawaii. Direct heat industrial applications were analyzed from a marketing, engineering, economic, environmental, and sociological standpoint to determine the most viable industries for the park. An extensive literature search produced 31 existing processes currently using geothermal heat. An additional list was compiled indicating industrial processes that require heat that could be provided by geothermal energy. From this information, 17 possible processes were selected for consideration. Careful scrutiny and analysis of these 17 processes revealed three thatmore » justified detailed economic workups. The three processes chosen for detailed analysis were: an ethanol plant using bagasse and wood as feedstock; a cattle feed mill using sugar cane leaf trash as feedstock; and a papaya processing facility providing both fresh and processed fruit. In addition, a research facility to assess and develop other processes was treated as a concept. Consideration was given to the impediments to development, the engineering process requirements and the governmental support for each process. The study describes the geothermal well site chosen, the pipeline to transmit the hydrothermal fluid, and the infrastructure required for the industrial park. A conceptual development plan for the ethanol plant, the feedmill and the papaya processing facility was prepared. The study concluded that a direct heat industrial park in Pahoa, Hawaii, involves considerable risks.« less

Ion acceleration and heating by kinetic Alfvén waves associated with magnetic reconnection

NASA Astrophysics Data System (ADS)

Liang, Ji; Lin, Yu; Johnson, Jay R.; Wang, Zheng-Xiong; Wang, Xueyi

2017-10-01

Our previous study on the generation and signatures of kinetic Alfvén waves (KAWs) associated with magnetic reconnection in a current sheet revealed that KAWs are a common feature during reconnection [Liang et al. J. Geophys. Res.: Space Phys. 121, 6526 (2016)]. In this paper, ion acceleration and heating by the KAWs generated during magnetic reconnection are investigated with a three-dimensional (3-D) hybrid model. It is found that in the outflow region, a fraction of inflow ions are accelerated by the KAWs generated in the leading bulge region of reconnection, and their parallel velocities gradually increase up to slightly super-Alfvénic. As a result of wave-particle interactions, an accelerated ion beam forms in the direction of the anti-parallel magnetic field, in addition to the core ion population, leading to the development of non-Maxwellian velocity distributions, which include a trapped population with parallel velocities consistent with the wave speed. The ions are heated in both parallel and perpendicular directions. In the parallel direction, the heating results from nonlinear Landau resonance of trapped ions. In the perpendicular direction, however, evidence of stochastic heating by the KAWs is found during the acceleration stage, with an increase of magnetic moment μ. The coherence in the perpendicular ion temperature T⊥ and the perpendicular electric and magnetic fields of KAWs also provides evidence for perpendicular heating by KAWs. The parallel and perpendicular heating of the accelerated beam occur simultaneously, leading to the development of temperature anisotropy with T⊥>T∥ . The heating rate agrees with the damping rate of the KAWs, and the heating is dominated by the accelerated ion beam. In the later stage, with the increase of the fraction of the accelerated ions, interaction between the accelerated beam and the core population also contributes to the ion heating, ultimately leading to overlap of the beams and an overall anisotropy with T∥>T⊥ .

Ion acceleration and heating by kinetic Alfvén waves associated with magnetic reconnection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liang, Ji; Lin, Yu; Johnson, Jay R.

In a previous study on the generation and signatures of kinetic Alfv en waves (KAWs) associated with magnetic reconnection in a current sheet revealed that KAWs are a common feature during reconnection [Liang et al. J. Geophys. Res.: Space Phys. 121, 6526 (2016)]. In this paper, ion acceleration and heating by the KAWs generated during magnetic reconnection are investigated with a three-dimensional (3-D) hybrid model. It is found that in the outflow region, a fraction of inflow ions are accelerated by the KAWs generated in the leading bulge region of reconnection, and their parallel velocities gradually increase up to slightly super-Alfv enic. As a result of waveparticle interactions, an accelerated ion beam forms in the direction of the anti-parallel magnetic field, in addition to the core ion population, leading to the development of non-Maxwellian velocity distributions, which include a trapped population with parallel velocities consistent with the wave speed. We then heat ions in both parallel and perpendicular directions. In the parallel direction, the heating results from nonlinear Landau resonance of trapped ions. In the perpendicular direction, however, evidence of stochastic heating by the KAWs is found during the acceleration stage, with an increase of magnetic moment μ. The coherence in the T more » $$\\perp$$ ion temperature and the perpendicular electric and magnetic fields of KAWs also provides evidence for perpendicular heating by KAWs. The parallel and perpendicular heating of the accelerated beam occur simultaneously, leading to the development of temperature anisotropy with the perpendicular temperature T $$\\perp$$>T $$\\parallel$$ temperature. The heating rate agrees with the damping rate of the KAWs, and the heating is dominated by the accelerated ion beam. In the later stage, with the increase of the fraction of the accelerated ions, interaction between the accelerated beam and the core population also contributes to the ion heating, ultimately leading to overlap of the beams and an overall anisotropy with T $$\\perp$$>T $$\\parallel$$.« less

Ion acceleration and heating by kinetic Alfvén waves associated with magnetic reconnection

DOE PAGES

Liang, Ji; Lin, Yu; Johnson, Jay R.; ...

2017-09-19

In a previous study on the generation and signatures of kinetic Alfv en waves (KAWs) associated with magnetic reconnection in a current sheet revealed that KAWs are a common feature during reconnection [Liang et al. J. Geophys. Res.: Space Phys. 121, 6526 (2016)]. In this paper, ion acceleration and heating by the KAWs generated during magnetic reconnection are investigated with a three-dimensional (3-D) hybrid model. It is found that in the outflow region, a fraction of inflow ions are accelerated by the KAWs generated in the leading bulge region of reconnection, and their parallel velocities gradually increase up to slightly super-Alfv enic. As a result of waveparticle interactions, an accelerated ion beam forms in the direction of the anti-parallel magnetic field, in addition to the core ion population, leading to the development of non-Maxwellian velocity distributions, which include a trapped population with parallel velocities consistent with the wave speed. We then heat ions in both parallel and perpendicular directions. In the parallel direction, the heating results from nonlinear Landau resonance of trapped ions. In the perpendicular direction, however, evidence of stochastic heating by the KAWs is found during the acceleration stage, with an increase of magnetic moment μ. The coherence in the T more » $$\\perp$$ ion temperature and the perpendicular electric and magnetic fields of KAWs also provides evidence for perpendicular heating by KAWs. The parallel and perpendicular heating of the accelerated beam occur simultaneously, leading to the development of temperature anisotropy with the perpendicular temperature T $$\\perp$$>T $$\\parallel$$ temperature. The heating rate agrees with the damping rate of the KAWs, and the heating is dominated by the accelerated ion beam. In the later stage, with the increase of the fraction of the accelerated ions, interaction between the accelerated beam and the core population also contributes to the ion heating, ultimately leading to overlap of the beams and an overall anisotropy with T $$\\perp$$>T $$\\parallel$$.« less

Variable temperature seat climate control system

DOEpatents

Karunasiri, Tissa R.; Gallup, David F.; Noles, David R.; Gregory, Christian T.

1997-05-06

A temperature climate control system comprises a variable temperature seat, at least one heat pump, at least one heat pump temperature sensor, and a controller. Each heat pump comprises a number of Peltier thermoelectric modules for temperature conditioning the air in a main heat exchanger and a main exchanger fan for passing the conditioned air from the main exchanger to the variable temperature seat. The Peltier modules and each main fan may be manually adjusted via a control switch or a control signal. Additionally, the temperature climate control system may comprise a number of additional temperature sensors to monitor the temperature of the ambient air surrounding the occupant as well as the temperature of the conditioned air directed to the occupant. The controller is configured to automatically regulate the operation of the Peltier modules and/or each main fan according to a temperature climate control logic designed both to maximize occupant comfort during normal operation, and minimize possible equipment damage, occupant discomfort, or occupant injury in the event of a heat pump malfunction.

Grain Structure Control of Additively Manufactured Metallic Materials

PubMed Central

Faierson, Eric J.

2017-01-01

Grain structure control is challenging for metal additive manufacturing (AM). Grain structure optimization requires the control of grain morphology with grain size refinement, which can improve the mechanical properties of additive manufactured components. This work summarizes methods to promote fine equiaxed grains in both the additive manufacturing process and subsequent heat treatment. Influences of temperature gradient, solidification velocity and alloy composition on grain morphology are discussed. Equiaxed solidification is greatly promoted by introducing a high density of heterogeneous nucleation sites via powder rate control in the direct energy deposition (DED) technique or powder surface treatment for powder-bed techniques. Grain growth/coarsening during post-processing heat treatment can be restricted by presence of nano-scale oxide particles formed in-situ during AM. Grain refinement of martensitic steels can also be achieved by cyclic austenitizing in post-processing heat treatment. Evidently, new alloy powder design is another sustainable method enhancing the capability of AM for high-performance components with desirable microstructures.

[INVITED] Coupling of polarisation of high frequency electric field and electronic heat conduction in laser created plasma

NASA Astrophysics Data System (ADS)

Gamaly, Eugene G.; Rode, Andrei V.

2016-08-01

Powerful short laser pulse focused on a surface swiftly transforms the solid into the thermally and electrically inhomogeneous conductive plasma with the large temperature and dielectric permeability gradients across the focal spot. The laser-affected spot becomes thermally inhomogeneous with where temperature has maximum in the centre and gradually decreasing to the boundaries of the spot in accord to the spatial intensity distribution of the Gaussian pulse. Here we study the influence of laser polarisation on ionization and absorption of laser radiation in the focal spot. In this paper we would like to discuss new effect in thermally inhomogeneous plasma under the action of imposed high frequency electric field. We demonstrate that high-frequency (HF) electric field is coupled with the temperature gradient generating the additional contribution to the conventional electronic heat flow. The additional heat flow strongly depends on the polarisation of the external field. It appears that effect has maximum when the imposed electric field is collinear to the thermal gradient directed along the radius of a circular focal spot. Therefore, the linear polarised field converts the circular laser affected spot into an oval with the larger oval's axis parallel to the field direction. We compare the developed theory to the available experiments, discuss the results and future directions.

Application of X-Ray Computer Tomography for Observing the Central Void Formations and the Fuel Pin Deformations of Irradiated FBR Fuel Assemblies

NASA Astrophysics Data System (ADS)

Katsuyama, Kozo; Nagamine, Tsuyoshi; Furuya, Hirotaka

2010-10-01

In order to observe the structural change in the interior of irradiated fuel assemblies, a non-destructive post-irradiation examination (PIE) technique using X-ray computer tomography (X-ray CT) was developed. This X-ray CT technique was applied to observe the central void formations and fuel pin deformations of fuel assemblies which had been irradiated at high linear heat rating. The central void sizes in all fuel pins were measured on five cross sections of the core fuel column as a parameter for evaluating fuel thermal performance. In addition, the fuel pin deformations were analyzed from X-ray CT images obtained along the axial direction of a fuel assembly at the same separation interval. A dependence of void size on the linear heat rating was seen in the fuel assembly irradiated at high linear heat rating. In addition, significant undulations of the fuel pin were observed along the axial direction, coinciding with the wrapping wire pitch in the core fuel column. Application of the developed technique should provide enhanced resolution of measurements and simplify fuel PIEs.

Geothermal heating enhances atmospheric asymmetries on synchronously rotating planets

NASA Astrophysics Data System (ADS)

Haqq-Misra, Jacob; Kopparapu, Ravi Kumar

2015-01-01

Earth-like planets within the liquid water habitable zone of M-type stars may evolve into synchronous rotators. On these planets, the substellar hemisphere experiences perpetual daylight while the opposing antistellar hemisphere experiences perpetual darkness. Because the night-side hemisphere has no direct source of energy, the air over this side of the planet is prone to freeze out and deposit on the surface, which could result in atmospheric collapse. However, general circulation models (GCMs) have shown that atmospheric dynamics can counteract this problem and provide sufficient energy transport to the antistellar side. Here, we use an idealized GCM to consider the impact of geothermal heating on the habitability of synchronously rotating planets. Geothermal heating may be expected due to tidal interactions with the host star, and the effects of geothermal heating provide additional habitable surface area and may help to induce melting of ice on the antistellar hemisphere. We also explore the persistence of atmospheric asymmetries between the Northern and Southern hemispheres, and we find that the direction of the meridional circulation (for rapidly rotating planets) or the direction of zonal wind (for slowly rotating planets) reverses on either side of the substellar point. We show that the zonal circulation approaches a theoretical state similar to a Walker circulation only for slowly rotating planets, while rapidly rotating planets show a zonal circulation with the opposite direction. We find that a cross-polar circulation is present in all cases and provides an additional mechanism of mass and energy transport from the substellar to antistellar point. Characterization of the atmospheres of synchronously rotating planets should include consideration of hemispheric differences in meridional circulation and examination of transport due to cross-polar flow.

Rapid and enhanced activation of microporous coordination polymers by flowing supercritical CO.sub.2

DOEpatents

Matzger, Adam J.; Liu, Baojian; Wong-Foy, Antek G.

2016-07-19

Flowing supercritical CO.sub.2 is used to activate metal organic framework materials (MOF). MOFs are activated directly from N,N-dimethylformamide (DMF) thus avoiding exchange with a volatile solvent. Most MCPs display increased surface areas directly after treatment although those with coordinatively unsaturated metal centers benefit from additional heating.

Numerical and Analytical Modeling of Laser Deposition with Preheating (Preprint)

DTIC Science & Technology

2007-03-01

temperature materials, Numerical Heat Transfer 11 (1987) 477-491. [9] L. Han, F.W. Liou, K.M. Phatk, Modeling of laser cladding with powder injection... cladding process. This laser additive manufacturing technique allows quick fabrication of fully-dense metallic components directly from Computer...1, laser deposition uses a focused laser beam as a heat source to create a melt pool on an underlying substrate. Powder material is then injected

Changes in air temperature and its relation to ambulance transports due to heat stroke in all 47 prefectures of Japan.

PubMed

Murakami, Shoko; Miyatake, Nobuyuki; Sakano, Noriko

2012-09-01

Changes in air temperature and its relation to ambulance transports due to heat stroke in all 47 prefectures, in Japan were evaluated. Data on air temperature were obtained from the Japanese Meteorological Agency. Data on ambulance transports due to heat stroke was directly obtained from the Fire and Disaster Management Agency, Japan. We also used the number of deaths due to heat stroke from the Ministry of Health, Labour and Welfare, Japan, and population data from the Ministry of Internal Affairs and Communications. Chronological changes in parameters of air temperature were analyzed. In addition, the relation between air temperature and ambulance transports due to heat stroke in August 2010 was also evaluated by using an ecological study. Positive and significant changes in the parameters of air temperature that is, the mean air temperature, mean of the highest air temperature, and mean of the lowest air temperature were noted in all 47 prefectures. In addition, changes in air temperature were accelerated when adjusted for observation years. Ambulance transports due to heat stroke was significantly correlated with air temperature in the ecological study. The highest air temperature was significantly linked to ambulance transports due to heat stroke, especially in elderly subjects. Global warming was demonstrated in all 47 prefectures in Japan. In addition, the higher air temperature was closely associated with higher ambulance transports due to heat stroke in Japan.

Environmental Temperature and Thermal Indices: What Is the Most Effective Predictor of Heat-Related Mortality in Different Geographical Contexts?

PubMed Central

Morabito, Marco; Crisci, Alfonso; Messeri, Alessandro; Capecchi, Valerio; Modesti, Pietro Amedeo; Gensini, Gian Franco; Orlandini, Simone

2014-01-01

The aim of this study is to identify the most effective thermal predictor of heat-related very-elderly mortality in two cities located in different geographical contexts of central Italy. We tested the hypothesis that use of the state-of-the-art rational thermal indices, the Universal Thermal Climate Index (UTCI), might provide an improvement in predicting heat-related mortality with respect to other predictors. Data regarding very elderly people (≥75 years) who died in inland and coastal cities from 2006 to 2008 (May–October) and meteorological and air pollution were obtained from the regional mortality and environmental archives. Rational (UTCI) and direct thermal indices represented by a set of bivariate/multivariate apparent temperature indices were assessed. Correlation analyses and generalized additive models were applied. The Akaike weights were used for the best model selection. Direct multivariate indices showed the highest correlations with UTCI and were also selected as the best thermal predictors of heat-related mortality for both inland and coastal cities. Conversely, the UTCI was never identified as the best thermal predictor. The use of direct multivariate indices, which also account for the extra effect of wind speed and/or solar radiation, revealed the best fitting with all-cause, very-elderly mortality attributable to heat stress. PMID:24523657

Environmental temperature and thermal indices: what is the most effective predictor of heat-related mortality in different geographical contexts?

PubMed

Morabito, Marco; Crisci, Alfonso; Messeri, Alessandro; Capecchi, Valerio; Modesti, Pietro Amedeo; Gensini, Gian Franco; Orlandini, Simone

2014-01-01

The aim of this study is to identify the most effective thermal predictor of heat-related very-elderly mortality in two cities located in different geographical contexts of central Italy. We tested the hypothesis that use of the state-of-the-art rational thermal indices, the Universal Thermal Climate Index (UTCI), might provide an improvement in predicting heat-related mortality with respect to other predictors. Data regarding very elderly people (≥ 75 years) who died in inland and coastal cities from 2006 to 2008 (May-October) and meteorological and air pollution were obtained from the regional mortality and environmental archives. Rational (UTCI) and direct thermal indices represented by a set of bivariate/multivariate apparent temperature indices were assessed. Correlation analyses and generalized additive models were applied. The Akaike weights were used for the best model selection. Direct multivariate indices showed the highest correlations with UTCI and were also selected as the best thermal predictors of heat-related mortality for both inland and coastal cities. Conversely, the UTCI was never identified as the best thermal predictor. The use of direct multivariate indices, which also account for the extra effect of wind speed and/or solar radiation, revealed the best fitting with all-cause, very-elderly mortality attributable to heat stress.

Fundamental mechanisms that influence the estimate of heat transfer to gas turbine blades

NASA Technical Reports Server (NTRS)

Graham, R. W.

1979-01-01

Estimates of the heat transfer from the gas to stationary (vanes) or rotating blades poses a major uncertainty due to the complexity of the heat transfer processes. The gas flow through these blade rows is three dimensional with complex secondary viscous flow patterns that interact with the endwalls and blade surfaces. In addition, upstream disturbances, stagnation flow, curvature effects, and flow acceleration complicate the thermal transport mechanisms in the boundary layers. Some of these fundamental heat transfer effects are discussed. The chief purpose of the discussion is to acquaint those in the heat transfer community, not directly involved in gas turbines, of the seriousness of the problem and to recommend some basic research that would improve the capability for predicting gas-side heat transfer on turbine blades and vanes.

Mitigation of CO2 emissions from the EU-15 building stock: beyond the EU Directive on the Energy Performance of Buildings.

PubMed

Petersdorff, Carsten; Boermans, Thomas; Harnisch, Jochen

2006-09-01

GOAL SCOPE AND BACKGROUND: The European Directive on Energy Performance of Buildings which came into force 16 December 2002 will be implemented in the legislation of Member States by 4 January 2006. In addition to the aim of improving the overall energy efficiency of new buildings, large existing buildings will become a target for improvement, as soon as they undergo significant renovation. The building sector is responsible for about 40% of Europe's total end energy consumption and hence this Directive is an important step for the European Union in order that it should reach the level of saving required by the Kyoto Agreement. In this the EU is committed to reduce CO2 emissions relative to the base year of 1990 by 8 per cent, by 2010. But what will be the impact of the new Directive, how large could be the impacts of extending the obligation for energy efficiency retrofitting towards smaller buildings? Can improvement of the insulation offset or reduce the growing energy consumption from the increasing installation of cooling installations? EURIMA, the European Insulation Manufacturers Association and EuroACE, the European Alliance of Companies for Energy Efficiency in Buildings, asked Ecofys to address these questions. The effect of the EPB Directive on the emissions associated with the heating energy consumption of the total EU 15 building stock has been examined in a model calculation, using the Built Environment Analysis Model (BEAM), which was developed by Ecofys to investigate energy saving measures in the building stock. The great complexity of the EU-15 building stock had to be simplified by examining five standard buildings with eight insulation standards, which are assigned to building age and renovation status. Furthermore, three climatic regions (cold, moderate, warm) were distinguished for the calculation of the heating energy demand. This gave a basic 210 building types for which the heating energy demand and CO2 emissions from heating were calculated according to the principles of the European Norm EN 832. The model calculations demonstrates that the main contributor to the total heating related CO2 emissions of 725 Mt/a from the EU building stock in 2002 is the residential sector (77%) while the remaining 23% originates from non-residential buildings. In the residential sector, single-family houses represent the largest group responsible for 60% of the total CO2 emissions equivalent to 435 Mt/a. THE TECHNICAL POTENTIAL: If all retrofit measures in the scope of the Directive were realised immediately for the complete residential and non-residential building stock the overall CO2 emission savings would add up to 82 Mt/a. An additional saving potential compared to the Directive of 69 Mt/a would be created if the scope of the Directive was extended to cover retrofit measures in multi-family dwellings (200-1000 m2) and non-residential buildings smaller than 1000 m2 used floor space. In addition including the large group of single-family dwellings would lead to a potential for additional CO2 emission reductions compared to the Directive of 316 Mt/a. TEMPORAL MOBILIZATION OF THE POTENTIAL: Calculations based on the building stock as it develops over time with average retrofit rates demonstrated that regulations introduced following the EPB Directive result in a CO2 emissions decrease of 34 Mt/a by the year 2010 compared to the business as usual scenario. Extending the scope of the EPB Directive to all residential buildings (including single and multi-family dwellings), the CO2 emission savings potential over the 'business as usual' scenario could be doubled to 69 Mt/a in the year 2010. This creates an additional saving potential compared to the Directive of 36 Mt/a. COOLING DEMAND: The analysis demonstrated that in warm climatic zones the cooling demand can be reduced drastically by a combination of lowering the internal heat loads and by improved insulation. With the reduction of the heat loads to a moderate level the cooling demand, e.g. of a terraced house located in Madrid, can be reduced by an additional 85% if the insulation level is improved appropriately. This study demonstrates that the European Directive on Energy Performance of Buildings will have a significant impact on the CO2 emissions of the European building stock. The main saving potential lies in insulation of the existing building stock. Beyond this, CO2 emissions could, however, be greatly reduced if the scope of the Directive were to be extended to include retrofit of smaller buildings. The reductions should be seen in relation to the remaining gap of 190 Mt CO2 eq. per annum between the current emission levels of EU-15 and the target under the Kyoto-Protocol for the year 2010. The energy and industrial sector will probably contribute only a fraction of this reduction via the newly established EU emissions trading scheme and connected projects under the flexible mechanism. In addition, the traffic sector is likely to continue its growth path leading to a widening of the gap. Thus, there is likely to be considerable pressure on the EU building sector to contribute to the EU climate targets beyond what will be achieved by means of the current EPB Directive. Legislators on the EU and national level are therefore advised to take accelerated actions to tap the very significant emission reduction potentials available in the EU building stock.

Direct Heating of a Laser-Imploded Core by Ultraintense Laser-Driven Ions

NASA Astrophysics Data System (ADS)

Kitagawa, Y.; Mori, Y.; Komeda, O.; Ishii, K.; Hanayama, R.; Fujita, K.; Okihara, S.; Sekine, T.; Satoh, N.; Kurita, T.; Takagi, M.; Watari, T.; Kawashima, T.; Kan, H.; Nishimura, Y.; Sunahara, A.; Sentoku, Y.; Nakamura, N.; Kondo, T.; Fujine, M.; Azuma, H.; Motohiro, T.; Hioki, T.; Kakeno, M.; Miura, E.; Arikawa, Y.; Nagai, T.; Abe, Y.; Ozaki, S.; Noda, A.

2015-05-01

A novel direct core heating fusion process is introduced, in which a preimploded core is predominantly heated by energetic ions driven by LFEX, an extremely energetic ultrashort pulse laser. Consequently, we have observed the D (d ,n )He 3 -reacted neutrons (DD beam-fusion neutrons) with the yield of 5 ×108 n /4 π sr . Examination of the beam-fusion neutrons verified that the ions directly collide with the core plasma. While the hot electrons heat the whole core volume, the energetic ions deposit their energies locally in the core, forming hot spots for fuel ignition. As evidenced in the spectrum, the process simultaneously excited thermal neutrons with the yield of 6 ×107 n /4 π sr , raising the local core temperature from 0.8 to 1.8 keV. A one-dimensional hydrocode STAR 1D explains the shell implosion dynamics including the beam fusion and thermal fusion initiated by fast deuterons and carbon ions. A two-dimensional collisional particle-in-cell code predicts the core heating due to resistive processes driven by hot electrons, and also the generation of fast ions, which could be an additional heating source when they reach the core. Since the core density is limited to 2 g /cm3 in the current experiment, neither hot electrons nor fast ions can efficiently deposit their energy and the neutron yield remains low. In future work, we will achieve the higher core density (>10 g /cm3 ); then hot electrons could contribute more to the core heating via drag heating. Together with hot electrons, the ion contribution to fast ignition is indispensable for realizing high-gain fusion. By virtue of its core heating and ignition, the proposed scheme can potentially achieve high gain fusion.

Direct heating of a laser-imploded core by ultraintense laser-driven ions.

PubMed

Kitagawa, Y; Mori, Y; Komeda, O; Ishii, K; Hanayama, R; Fujita, K; Okihara, S; Sekine, T; Satoh, N; Kurita, T; Takagi, M; Watari, T; Kawashima, T; Kan, H; Nishimura, Y; Sunahara, A; Sentoku, Y; Nakamura, N; Kondo, T; Fujine, M; Azuma, H; Motohiro, T; Hioki, T; Kakeno, M; Miura, E; Arikawa, Y; Nagai, T; Abe, Y; Ozaki, S; Noda, A

2015-05-15

A novel direct core heating fusion process is introduced, in which a preimploded core is predominantly heated by energetic ions driven by LFEX, an extremely energetic ultrashort pulse laser. Consequently, we have observed the D(d,n)^{3}He-reacted neutrons (DD beam-fusion neutrons) with the yield of 5×10^{8} n/4π sr. Examination of the beam-fusion neutrons verified that the ions directly collide with the core plasma. While the hot electrons heat the whole core volume, the energetic ions deposit their energies locally in the core, forming hot spots for fuel ignition. As evidenced in the spectrum, the process simultaneously excited thermal neutrons with the yield of 6×10^{7} n/4π sr, raising the local core temperature from 0.8 to 1.8 keV. A one-dimensional hydrocode STAR 1D explains the shell implosion dynamics including the beam fusion and thermal fusion initiated by fast deuterons and carbon ions. A two-dimensional collisional particle-in-cell code predicts the core heating due to resistive processes driven by hot electrons, and also the generation of fast ions, which could be an additional heating source when they reach the core. Since the core density is limited to 2 g/cm^{3} in the current experiment, neither hot electrons nor fast ions can efficiently deposit their energy and the neutron yield remains low. In future work, we will achieve the higher core density (>10 g/cm^{3}); then hot electrons could contribute more to the core heating via drag heating. Together with hot electrons, the ion contribution to fast ignition is indispensable for realizing high-gain fusion. By virtue of its core heating and ignition, the proposed scheme can potentially achieve high gain fusion.

Modeling 3D conjugate heat and mass transfer for turbulent air drying of Chilean papaya in a direct contact dryer

NASA Astrophysics Data System (ADS)

Lemus-Mondaca, Roberto A.; Vega-Gálvez, Antonio; Zambra, Carlos E.; Moraga, Nelson O.

2017-01-01

A 3D model considering heat and mass transfer for food dehydration inside a direct contact dryer is studied. The k- ɛ model is used to describe turbulent air flow. The samples thermophysical properties as density, specific heat, and thermal conductivity are assumed to vary non-linearly with temperature. FVM, SIMPLE algorithm based on a FORTRAN code are used. Results unsteady velocity, temperature, moisture, kinetic energy and dissipation rate for the air flow are presented, whilst temperature and moisture values for the food also are presented. The validation procedure includes a comparison with experimental and numerical temperature and moisture content results obtained from experimental data, reaching a deviation 7-10 %. In addition, this turbulent k- ɛ model provided a better understanding of the transport phenomenon inside the dryer and sample.

Results of convective heating tests of a longitudinal gap on the Rockwell flat plate model (15-0, insert 7) in the NASA/Ames Research Center

NASA Technical Reports Server (NTRS)

Quan, M.; Lockman, W. K.

1975-01-01

Results are presented which were obtained from tests in a hypersonic wind tunnel to determine aerodynamic heating rates in a gap running parallel or slightly askew to the flow direction. The model used was a flat plate instrumented in thin-skin sections with chromelconstantan thermocouples. Heating rate profiles lengthwise along and down into the gap were obtained, and additional data were obtained from a total temperature probe and rake fabricated during the test to investigate an apparent aerodynamic cooling trend in the gap. Model variables were width, depth, length, and orientation of the gap relative to the flow direction. The tests were conducted at Mach 5.1 and Reynolds numbers per foot of 500,000, 1,000,000, and 2,000,000.

Design of plate directional heat transmission structure based on layered thermal metamaterials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, L. K.; Yu, Z. F.; Huang, J., E-mail: slk-0-1999@163.com

2016-02-15

Invisibility cloaks based on transformation optics are often closed structures; however, such a structure limits the kinds of objects that can be placed in the cloak. In this work, we adopt a transformation thermodynamics approach to design an “open cloak”, called a plate directional heat transmission structure, which is capable of guiding heat fluxes to the flank region of the metamaterial device. The most fascinating and unique feature of the device is that the lower surface can remain at a lower temperature compared with the SiO{sub 2} aerogel thermal insulation material. Our results are expected to markedly enhance capabilities inmore » thermal protection, thermal-energy utilization, and domains beyond. In addition to the theoretical analysis, the present design is demonstrated in numerical simulations based on finite element calculations.« less

Application of Simulated Reactivity Feedback in Nonnuclear Testing of a Direct-Drive Gas-Cooled Reactor

NASA Technical Reports Server (NTRS)

Bragg-Sitton, S. M.; Webster, K. L.

2007-01-01

Nonnuclear testing can be a valuable tool in the development of an in-space nuclear power or propulsion system. In a nonnuclear test facility, electric heaters are used to simulate heat from nuclear fuel. Standard testing allows one to fully assess thermal, heat transfer, and stress related attributes of a given system but fails to demonstrate the dynamic response that would be present in an integrated, fueled reactor system. The integration of thermal hydraulic hardware tests with simulated neutronic response provides a bridge between electrically heated testing and full nuclear testing. By implementing a neutronic response model to simulate the dynamic response that would be expected in a fueled reactor system, one can better understand system integration issues, characterize integrated system response times and response and response characteristics, and assess potential design improvements with a relatively small fiscal investment. Initial system dynamic response testing was demonstrated on the integrated SAFE 100a heat pipe cooled, electrically heated reactor and heat exchanger hardware. This Technical Memorandum discusses the status of the planned dynamic test methodology for implementation in the direct-drive gas-cooled reactor testing and assesses the additional instrumentation needed to implement high-fidelity dynamic testing.

The Response of the Ocean Thermal Skin Layer to Variations in Incident Infrared Radiation

NASA Astrophysics Data System (ADS)

Wong, Elizabeth W.; Minnett, Peter J.

2018-04-01

Ocean warming trends are observed and coincide with the increase in concentrations of greenhouse gases in the atmosphere resulting from human activities. At the ocean surface, most of the incoming infrared (IR) radiation is absorbed within the top micrometers of the ocean's surface where the thermal skin layer (TSL) exists. Thus, the incident IR radiation does not directly heat the upper few meters of the ocean. This paper investigates the physical mechanism between the absorption of IR radiation and its effect on heat transfer at the air-sea boundary. The hypothesis is that given the heat lost through the air-sea interface is controlled by the TSL, the TSL adjusts in response to variations in incident IR radiation to maintain the surface heat loss. This modulates the flow of heat from below and hence controls upper ocean heat content. This hypothesis is tested using the increase in incoming longwave radiation from clouds and analyzing vertical temperature profiles in the TSL retrieved from sea-surface emission spectra. The additional energy from the absorption of increasing IR radiation adjusts the curvature of the TSL such that the upward conduction of heat from the bulk of the ocean into the TSL is reduced. The additional energy absorbed within the TSL supports more of the surface heat loss. Thus, more heat beneath the TSL is retained leading to the observed increase in upper ocean heat content.

77 FR 72746 - Regulation of Fuels and Fuel Additives: Modifications to Renewable Fuel Standard and Diesel...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-12-06

...EPA published a direct final rule on October 9, 2012 to amend the definition of heating oil in 40 CFR 80.1401 in the Renewable Fuel Standard (``RFS'') program under section 211(o) of the Clean Air Act. The direct final rule also amended requirements under EPA's diesel sulfur program related to the sulfur content of locomotive and marine diesel fuel produced by transmix processors, and the fuel marker requirements for 500 ppm sulfur locomotive and marine (LM) diesel fuel to allow for solvent yellow 124 marker to transition out of the distribution system. Because EPA received adverse comments on the heating oil definition and transmix amendments, we are withdrawing those portions of the direct final rule. Because EPA did not receive adverse comments with respect to the yellow marker amendments, those amendments will become effective as indicated in the direct final rule.

Climate Change and Health Risks from Extreme Heat and Air Pollution in the Eastern United States

NASA Astrophysics Data System (ADS)

Limaye, V.; Vargo, J.; Harkey, M.; Holloway, T.; Meier, P.; Patz, J.

2013-12-01

Climate change is expected to exacerbate health risks from exposure to extreme heat and air pollution through both direct and indirect mechanisms. Directly, warmer ambient temperatures promote biogenic emissions of ozone precursors and favor the formation of ground-level ozone, while an anticipated increase in the frequency of stagnant air masses will allow fine particulates to accumulate. Indirectly, warmer summertime temperatures stimulate energy demand and exacerbate polluting emissions from the electricity sector. Thus, while technological adaptations such as air conditioning can reduce risks from exposures to extreme heat, they can trigger downstream damage to air quality and public health. Through an interdisciplinary modeling effort, we quantify the impacts of climate change on ambient temperatures, summer energy demand, air quality, and public health. The first phase of this work explores how climate change will directly impact the burden of heat-related mortality. Climatic patterns, demographic trends, and epidemiologic risk models suggest that populations in the eastern United States are likely to experience an increasing heat stress mortality burden in response to rising summertime air temperatures. We use North American Regional Climate Change Assessment Program modeling data to estimate mid-century 2-meter air temperatures and humidity across the eastern US from June-August, and quantify how long-term changes in actual and apparent temperatures from present-day will affect the annual burden of heat-related mortality across this region. With the US Environmental Protection Agency's Environmental Benefits Mapping and Analysis Program, we estimate health risks using concentration-response functions, which relate temperature increases to changes in annual mortality rates. We compare mid-century summertime temperature data, downscaled using the Weather Research and Forecasting model, to 2007 baseline temperatures at a 12 km resolution in order to estimate the number of annual excess deaths attributable to increased summer temperatures. Warmer average temperatures are expected to cause 173 additional deaths due to cardiovascular stress, while higher minimum temperatures will cause 67 additional deaths. This work particularly improves on the spatial resolution of published analyses of heat-related mortality in the US.

Infrared preheating to improve interlayer strength of big area additive manufacturing (BAAM) components

DOE PAGES

Kishore, Vidya; Ajinjeru, Christine; Nycz, Andrzej; ...

2017-03-01

The Big Area Additive Manufacturing (BAAM) system can print structures on the order of several meters at high extrusion rates, thereby having the potential to significantly impact automotive, aerospace and energy sectors. The functional use of such parts, however, may be limited by mechanical anisotropy in which the strength of printed parts across successive layers in the build direction (z-direction) is significantly lower than the corresponding in-plane strength (x-y directions). This has been primarily attributed to poor bonding between printed layers as the lower layers cool below the glass transition temperature (Tg) before the next layer is deposited. Therefore, themore » potential of using infrared heating is considered for increasing the surface temperature of the printed layer just prior to deposition of new material to improve the interlayer strength of the components. This study found significant improvements in bond strength for the deposition of acrylonitrile butadiene styrene (ABS) reinforced with 20% chopped carbon fiber when the surface temperature of the substrate material was increased from below Tg to close to or above Tg using infrared heating.« less

Infrared preheating to improve interlayer strength of big area additive manufacturing (BAAM) components

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kishore, Vidya; Ajinjeru, Christine; Nycz, Andrzej

The Big Area Additive Manufacturing (BAAM) system can print structures on the order of several meters at high extrusion rates, thereby having the potential to significantly impact automotive, aerospace and energy sectors. The functional use of such parts, however, may be limited by mechanical anisotropy in which the strength of printed parts across successive layers in the build direction (z-direction) is significantly lower than the corresponding in-plane strength (x-y directions). This has been primarily attributed to poor bonding between printed layers as the lower layers cool below the glass transition temperature (Tg) before the next layer is deposited. Therefore, themore » potential of using infrared heating is considered for increasing the surface temperature of the printed layer just prior to deposition of new material to improve the interlayer strength of the components. This study found significant improvements in bond strength for the deposition of acrylonitrile butadiene styrene (ABS) reinforced with 20% chopped carbon fiber when the surface temperature of the substrate material was increased from below Tg to close to or above Tg using infrared heating.« less

Infrared Preheating to Enhance Interlayer Strength of Components Printed on the Big Area Additive Manufacturing (BAAM) System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kishore, Vidya; Ajinjeru, Christine; Duty, Chad E

The Big Area Additive Manufacturing (BAAM) system has the capacity to print structures on the order of several meters at a rate exceeding 50 kg/h, thereby having the potential to significantly impact the production of components in automotive, aerospace and energy sectors. However, a primary issue that limits the functional use of such parts is mechanical anisotropy. The strength of printed parts across successive layers in the build direction (z-direction) is significantly lower than the corresponding in-plane strength (x-y directions). This is largely due to poor bonding between the printed layers as the lower layers cool below the glass transitionmore » temperature (Tg) before the next layer is deposited. This work explores the use of infrared heating to increase the surface temperature of the printed layer just prior to deposition of new material to improve the interlayer strength of the components. The material used in this study was acrylonitrile butadiene styrene (ABS) reinforced with 20% chopped carbon fiber by weight. Significant improvements in z-strength were observed for the parts whose surface temperature was increased from below Tg to close to or above Tg using infrared heating. Parameters such as print speed, nozzle diameter and extrusion temperature were also found to impact the heat input required to enhance interlayer adhesion without significantly degrading the polymer and compromising on surface finish.« less

Strategy for Texture Management in Metals Additive Manufacturing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kirka, Michael M.; Lee, Yousub; Greeley, Duncan A.

Additive manufacturing (AM) technologies have long been recognized for their ability to fabricate complex geometric components directly from models conceptualized through computers, allowing for complicated designs and assemblies to be fabricated at lower costs, with shorter time to market, and improved function. Lacking behind the design complexity aspect is the ability to fully exploit AM processes for control over texture within AM components. Currently, standard heat-fill strategies utilized in AM processes result in largely columnar grain structures. Here, we propose a point heat source fill for the electron beam melting (EBM) process through which the texture in AM materials canmore » be controlled. Using this point heat source strategy, the ability to form either columnar or equiaxed grain structures upon solidification through changes in the process parameters associated with the point heat source fill is demonstrated for the nickel-base superalloy, Inconel 718. Mechanically, the material is demonstrated to exhibit either anisotropic properties for the columnar-grained material fabricated through using the standard raster scan of the EBM process or isotropic properties for the equiaxed material fabricated using the point heat source fill.« less

Modeling of the WSTF frictional heating apparatus in high pressure systems

NASA Technical Reports Server (NTRS)

Skowlund, Christopher T.

1992-01-01

In order to develop a computer program able to model the frictional heating of metals in high pressure oxygen or nitrogen a number of additions have been made to the frictional heating model originally developed for tests in low pressure helium. These additions include: (1) a physical property package for the gases to account for departures from the ideal gas state; (2) two methods for spatial discretization (finite differences with quadratic interpolation or orthogonal collocation on finite elements) which substantially reduce the computer time required to solve the transient heat balance; (3) more efficient programs for the integration of the ordinary differential equations resulting from the discretization of the partial differential equations; and (4) two methods for determining the best-fit parameters via minimization of the mean square error (either a direct search multivariable simplex method or a modified Levenburg-Marquardt algorithm). The resulting computer program has been shown to be accurate, efficient and robust for determining the heat flux or friction coefficient vs. time at the interface of the stationary and rotating samples.

Strategy for Texture Management in Metals Additive Manufacturing

DOE PAGES

Kirka, Michael M.; Lee, Yousub; Greeley, Duncan A.; ...

2017-01-31

Additive manufacturing (AM) technologies have long been recognized for their ability to fabricate complex geometric components directly from models conceptualized through computers, allowing for complicated designs and assemblies to be fabricated at lower costs, with shorter time to market, and improved function. Lacking behind the design complexity aspect is the ability to fully exploit AM processes for control over texture within AM components. Currently, standard heat-fill strategies utilized in AM processes result in largely columnar grain structures. Here, we propose a point heat source fill for the electron beam melting (EBM) process through which the texture in AM materials canmore » be controlled. Using this point heat source strategy, the ability to form either columnar or equiaxed grain structures upon solidification through changes in the process parameters associated with the point heat source fill is demonstrated for the nickel-base superalloy, Inconel 718. Mechanically, the material is demonstrated to exhibit either anisotropic properties for the columnar-grained material fabricated through using the standard raster scan of the EBM process or isotropic properties for the equiaxed material fabricated using the point heat source fill.« less

Characteristics of phase-change materials containing oxide nano-additives for thermal storage.

PubMed

Teng, Tun-Ping; Yu, Chao-Chieh

2012-11-06

In this study, the authors report the production of nanocomposite-enhanced phase-change materials (NEPCMs) using the direct-synthesis method by mixing paraffin with alumina (Al2O3), titania (TiO2), silica (SiO2), and zinc oxide (ZnO) as the experimental samples. Al2O3, TiO2, SiO2, and ZnO were dispersed into three concentrations of 1.0, 2.0, and 3.0 wt.%. Through heat conduction and differential scanning calorimeter experiments to evaluate the effects of varying concentrations of the nano-additives on the heat conduction performance and thermal storage characteristics of NEPCMs, their feasibility for use in thermal storage was determined. The experimental results demonstrate that TiO2 is more effective than the other additives in enhancing both the heat conduction and thermal storage performance of paraffin for most of the experimental parameters. Furthermore, TiO2 reduces the melting onset temperature and increases the solidification onset temperature of paraffin. This allows the phase-change heat to be applicable to a wider temperature range, and the highest decreased ratio of phase-change heat is only 0.46%, compared to that of paraffin. Therefore, this study demonstrates that TiO2, added to paraffin to form NEPCMs, has significant potential for enhancing the thermal storage characteristics of paraffin.

Magnetization and heat-capacity measurements on Zn1-xCrxTe

NASA Astrophysics Data System (ADS)

Pekarek, T. M.; Luning, J. E.; Miotkowski, I.; Crooker, B. C.

1994-12-01

We have taken magnetization and calorimetric measurements on Zn1-xCrxTe (x=0.003). The heat-capacity measurements show a Schottky peak indicating an energy-level splitting of 3.1 K between the ground and first excited states. Above 1.5 K we observe additional heat capacity, which indicates the presence of additional low-energy vibronic excitations. The magnetization data reveal a small anisotropy (~7%) with the (111) direction giving the largest value. The magnetization data were fit with a model including a static Jahn-Teller distortion proposed previously in these materials [J. T. Vallin, G. A. Slack, S. Roberts, and A. E. Hughes, Phys. Rev. B 2, 4313 (1970)]. Reasonable agreement was found with the data for a spin-orbit parameter of -59 cm-1 and a Jahn-Teller energy of 320 cm-1.

Efficient Use of Cogeneration and Fuel Diversification

NASA Astrophysics Data System (ADS)

Kunickis, M.; Balodis, M.; Sarma, U.; Cers, A.; Linkevics, O.

2015-12-01

Energy policy of the European Community is implemented by setting various goals in directives and developing support mechanisms to achieve them. However, very often these policies and legislation come into contradiction with each other, for example Directive 2009/28/EC on the promotion of the use of energy from renewable sources and Directive 2012/27/EU on energy efficiency, repealing Directive 2004/8/EC on the promotion of cogeneration based on a useful heat demand. In this paper, the authors attempt to assess the potential conflicts between policy political objectives to increase the share of high-efficiency co-generation and renewable energy sources (RES), based on the example of Riga district heating system (DHS). If a new heat source using biomass is built on the right bank of Riga DHS to increase the share of RES, the society could overpay for additional heat production capacities, such as a decrease in the loading of existing generating units, thereby contributing to an inefficient use of existing capacity. As a result, the following negative consequences may arise: 1) a decrease in primary energy savings (PES) from high-efficiency cogeneration in Riga DHS, 2) an increase in greenhouse gas (GHG) emissions in the Baltic region, 3) the worsening security situation of electricity supply in the Latvian power system, 4) an increase in the electricity market price in the Lithuanian and Latvian price areas of Nord Pool power exchange. Within the framework of the research, calculations of PES and GHG emission volumes have been performed for the existing situation and for the situation with heat source, using biomass. The effect of construction of biomass heat source on power capacity balances and Nord Pool electricity prices has been evaluated.

Convective and Stratiform Precipitation Processes and their Relationship to Latent Heating

NASA Technical Reports Server (NTRS)

Tao, Wei-Kuo; Lang, Steve; Zeng, Xiping; Shige, Shoichi; Takayabu, Yukari

2009-01-01

The global hydrological cycle is central to the Earth's climate system, with rainfall and the physics of its formation acting as the key links in the cycle. Two-thirds of global rainfall occurs in the Tropics. Associated with this rainfall is a vast amount of heat, which is known as latent heat. It arises mainly due to the phase change of water vapor condensing into liquid droplets; three-fourths of the total heat energy available to the Earth's atmosphere comes from tropical rainfall. In addition, fresh water provided by tropical rainfall and its variability exerts a large impact upon the structure and motions of the upper ocean layer. An improved convective -stratiform heating (CSH) algorithm has been developed to obtain the 3D structure of cloud heating over the Tropics based on two sources of information: 1) rainfall information, namely its amount and the fraction due to light rain intensity, observed directly from the Precipitation Radar (PR) on board the TRMM satellite and 2) synthetic cloud physics information obtained from cloud-resolving model (CRM) simulations of cloud systems. The cloud simulations provide details on cloud processes, specifically latent heating, eddy heat flux convergence and radiative heating/cooling, that. are not directly observable by satellite. The new CSH algorithm-derived heating has a noticeably different heating structure over both ocean and land regions compared to the previous CSH algorithm. One of the major differences between new and old algorithms is that the level of maximum cloud heating occurs 1 to 1.5 km lower in the atmosphere in the new algorithm. This can effect the structure of the implied air currents associated with the general circulation of the atmosphere in the Tropics. The new CSH algorithm will be used provide retrieved heating data to other heating algorithms to supplement their performance.

Continuum simulation of heat transfer and solidification behavior of AlSi10Mg in Direct Metal Laser Sintering Process

NASA Astrophysics Data System (ADS)

Ojha, Akash; Samantaray, Mihir; Nath Thatoi, Dhirendra; Sahoo, Seshadev

2018-03-01

Direct Metal Laser Sintering (DMLS) process is a laser based additive manufacturing process, which built complex structures from powder materials. Using high intensity laser beam, the process melts and fuse the powder particles makes dense structures. In this process, the laser beam in terms of heat flux strikes the powder bed and instantaneously melts and joins the powder particles. The partial solidification and temperature distribution on the powder bed endows a high cooling rate and rapid solidification which affects the microstructure of the build part. During the interaction of the laser beam with the powder bed, multiple modes of heat transfer takes place in this process, that make the process very complex. In the present research, a comprehensive heat transfer and solidification model of AlSi10Mg in direct metal laser sintering process has been developed on ANSYS 17.1.0 platform. The model helps to understand the flow phenomena, temperature distribution and densification mechanism on the powder bed. The numerical model takes into account the flow, heat transfer and solidification phenomena. Simulations were carried out for sintering of AlSi10Mg powders in the powder bed having dimension 3 mm × 1 mm × 0.08 mm. The solidification phenomena are incorporated by using enthalpy-porosity approach. The simulation results give the fundamental understanding of the densification of powder particles in DMLS process.

Enhanced thermophysical properties via PAO superstructure

NASA Astrophysics Data System (ADS)

Pournorouz, Zahra; Mostafavi, Amirhossein; Pinto, Aditya; Bokka, Apparao; Jeon, Junha; Shin, Donghyun

2017-01-01

For the last few years, molten salt nanomaterials have attracted many scientists for their enhanced specific heat by doping a minute concentration of nanoparticles (up to 1% by weight). Likewise, enhancing the specific heat of liquid media is important in many aspects of engineering such as engine oil, coolant, and lubricant. However, such enhancement in specific heat was only observed for molten salts, yet other engineering fluids such as water, ethylene glycol, and oil have shown a decrease of specific heat with doped nanoparticles. Recent studies have shown that the observed specific heat enhancement resulted from unique nanostructures that were formed by molten salt molecules when interacting with nanoparticles. Thus, such enhancement in specific heat is only possible for molten salts because other fluids may not naturally form such nanostructures. In this study, we hypothesized such nanostructures can be mimicked through in situ formation of fabricated nano-additives, which are putative nanoparticles coated with useful organic materials (e.g., polar-group-ended organic molecules) leading to superstructures, and thus can be directly used for other engineering fluids. We first applied this approach to polyalphaolefin (PAO). A differential scanning calorimeter (DSC), a rheometer, and a customized setup were employed to characterize the heat capacity, viscosity, and thermal conductivity of PAO and PAO with fabricated nano-additives. Results showed 44.5% enhanced heat capacity and 19.8 and 22.98% enhancement for thermal conductivity and viscosity, respectively, by an addition of only 2% of fabricated nanostructures in comparison with pure PAO. Moreover, a partial melting of the polar-group-ended organic molecules was observed in the first thermal cycle and the peak disappeared in the following cycles. This indicates that the in situ formation of fabricated nano-additives spontaneously occurs in the thermal cycle to form nanostructures. Figure of merit analyses have been performed for the PAO superstructure to evaluate its performance for heat storage and transfer media.

Enhanced thermophysical properties via PAO superstructure.

PubMed

Pournorouz, Zahra; Mostafavi, Amirhossein; Pinto, Aditya; Bokka, Apparao; Jeon, Junha; Shin, Donghyun

2017-12-01

For the last few years, molten salt nanomaterials have attracted many scientists for their enhanced specific heat by doping a minute concentration of nanoparticles (up to 1% by weight). Likewise, enhancing the specific heat of liquid media is important in many aspects of engineering such as engine oil, coolant, and lubricant. However, such enhancement in specific heat was only observed for molten salts, yet other engineering fluids such as water, ethylene glycol, and oil have shown a decrease of specific heat with doped nanoparticles. Recent studies have shown that the observed specific heat enhancement resulted from unique nanostructures that were formed by molten salt molecules when interacting with nanoparticles. Thus, such enhancement in specific heat is only possible for molten salts because other fluids may not naturally form such nanostructures. In this study, we hypothesized such nanostructures can be mimicked through in situ formation of fabricated nano-additives, which are putative nanoparticles coated with useful organic materials (e.g., polar-group-ended organic molecules) leading to superstructures, and thus can be directly used for other engineering fluids. We first applied this approach to polyalphaolefin (PAO). A differential scanning calorimeter (DSC), a rheometer, and a customized setup were employed to characterize the heat capacity, viscosity, and thermal conductivity of PAO and PAO with fabricated nano-additives. Results showed 44.5% enhanced heat capacity and 19.8 and 22.98% enhancement for thermal conductivity and viscosity, respectively, by an addition of only 2% of fabricated nanostructures in comparison with pure PAO. Moreover, a partial melting of the polar-group-ended organic molecules was observed in the first thermal cycle and the peak disappeared in the following cycles. This indicates that the in situ formation of fabricated nano-additives spontaneously occurs in the thermal cycle to form nanostructures. Figure of merit analyses have been performed for the PAO superstructure to evaluate its performance for heat storage and transfer media.

Themis - A solar power station

NASA Astrophysics Data System (ADS)

Hillairet, J.

The organization, goals, equipment, costs, and performance of the French Themis (Thermo-helio-electric-MW) project are outlined. The program was begun for both the domestic energy market and for export. The installation comprises a molten eutectic salt loop which receives heat from radiators situated in a central tower. The salt transfers the heat to water for steam generation of electricity. A storage tank holds enough molten salt to supply one day's reserve of power, 40 MWh. A field of heliostats directs the suns rays for an estimated 2400 hr/yr onto the central receiver aperture, while 11 additional parabolic concentrators provide sufficient heat to keep the salt reservoir at temperatures exceeding 200 C. In a test run of several months during the spring of 1982 the heliostats directed the sun's rays with an average efficiency of 75 percent, yielding 2.3 MW of power at a system efficiency of 20.5 percent in completely automatic operation.

Optimization of heat treatment parameters for additive manufacturing and gravity casting AlSi10Mg alloy

NASA Astrophysics Data System (ADS)

Girelli, L.; Tocci, M.; Montesano, L.; Gelfi, M.; Pola, A.

2017-11-01

Additive manufacturing of metals is a production process developed in the last few years to realize net shape components with complex geometry and high performance. AlSi10Mg is one of the most widely used aluminium alloys, both in this field and in conventional foundry processes, for its significant mechanical properties combined with good corrosion resistance. In this paper the effect of heat treatment on AlSi10Mg alloy was investigated. Solution and ageing treatments were carried out with different temperatures and times on samples obtained by direct metal laser sintering and gravity casting in order to compare their performance. Microstructural analyses and hardness tests were performed to investigate the effectiveness of the heat treatment. The results were correlated to the sample microstructure and porosity, analysed by means of optical microscopy and density measurements. It was found that, in the additive manufactured samples, the heat treatment can reduce significantly the performance of the alloy also because of the increase of porosity due to entrapped gas during the deposition technique and that the higher the solution temperature the higher the increase of such defects. A so remarkable effect was not found in the conventional cast alloy.

Counterflow Regolith Heat Exchanger

NASA Technical Reports Server (NTRS)

Zubrin, Robert; Jonscher, Peter

2013-01-01

A problem exists in reducing the total heating power required to extract oxygen from lunar regolith. All such processes require heating a great deal of soil, and the heat energy is wasted if it cannot be recycled from processed material back into new material. The counterflow regolith heat exchanger (CoRHE) is a device that transfers heat from hot regolith to cold regolith. The CoRHE is essentially a tube-in-tube heat exchanger with internal and external augers attached to the inner rotating tube to move the regolith. Hot regolith in the outer tube is moved in one direction by a right-hand - ed auger, and the cool regolith in the inner tube is moved in the opposite direction by a left-handed auger attached to the inside of the rotating tube. In this counterflow arrangement, a large fraction of the heat from the expended regolith is transferred to the new regolith. The spent regolith leaves the heat exchanger close to the temperature of the cold new regolith, and the new regolith is pre-heated close to the initial temperature of the spent regolith. Using the CoRHE can reduce the heating requirement of a lunar ISRU system by 80%, reducing the total power consumption by a factor of two. The unique feature of this system is that it allows for counterflow heat exchange to occur between solids, instead of liquids or gases, as is commonly done. In addition, in variants of this concept, the hydrogen reduction can be made to occur within the counterflow heat exchanger itself, enabling a simplified lunar ISRU (in situ resource utilization) system with excellent energy economy and continuous nonbatch mode operation.

Direct contact, binary fluid geothermal boiler

DOEpatents

Rapier, Pascal M.

1982-01-01

Energy is extracted from geothermal brines by direct contact with a working fluid such as isobutane which is immiscible with the brine in a geothermal boiler. The geothermal boiler provides a distributor arrangement which efficiently contacts geothermal brine with the isobutane in order to prevent the entrainment of geothermal brine in the isobutane vapor which is directed to a turbine. Accordingly the problem of brine carry-over through the turbine causes corrosion and scaling thereof is eliminated. Additionally the heat exchanger includes straightening vanes for preventing startup and other temporary fluctuations in the transitional zone of the boiler from causing brine carryover into the turbine. Also a screen is provided in the heat exchanger to coalesce the working fluid and to assist in defining the location of the transitional zone where the geothermal brine and the isobutane are initially mixed.

Direct contact, binary fluid geothermal boiler

DOEpatents

Rapier, P.M.

1979-12-27

Energy is extracted from geothermal brines by direct contact with a working fluid such as isobutane which is immiscible with the brine in a geothermal boiler. The geothermal boiler provides a distributor arrangement which efficiently contacts geothermal brine with the isobutane in order to prevent the entrainment of geothermal brine in the isobutane vapor which is directed to a turbine. Accordingly the problem of brine carryover through the turbine causing corrosion and scaling thereof is eliminated. Additionally the heat exchanger includes straightening vanes for preventing startup and other temporary fluctuations in the transitional zone of the boiler from causing brine carryover into the turbine. Also a screen is provided in the heat exchanger to coalesce the working fluid and to assist in defining the location of the transitional zone where the geothermal brine and the isobutane are initially mixed.

Opportunities and Challenges for Personal Heat Exposure Research

PubMed Central

Kuras, Evan R.; Richardson, Molly B.; Calkins, Miriam M.; Ebi, Kristie L.; Hess, Jeremy J.; Kintziger, Kristina W.; Jagger, Meredith A.; Middel, Ariane; Scott, Anna A.; Spector, June T.; Uejio, Christopher K.; Vanos, Jennifer K.; Zaitchik, Benjamin F.; Gohlke, Julia M.

2017-01-01

Background: Environmental heat exposure is a public health concern. The impacts of environmental heat on mortality and morbidity at the population scale are well documented, but little is known about specific exposures that individuals experience. Objectives: The first objective of this work was to catalyze discussion of the role of personal heat exposure information in research and risk assessment. The second objective was to provide guidance regarding the operationalization of personal heat exposure research methods. Discussion: We define personal heat exposure as realized contact between a person and an indoor or outdoor environment that poses a risk of increases in body core temperature and/or perceived discomfort. Personal heat exposure can be measured directly with wearable monitors or estimated indirectly through the combination of time–activity and meteorological data sets. Complementary information to understand individual-scale drivers of behavior, susceptibility, and health and comfort outcomes can be collected from additional monitors, surveys, interviews, ethnographic approaches, and additional social and health data sets. Personal exposure research can help reveal the extent of exposure misclassification that occurs when individual exposure to heat is estimated using ambient temperature measured at fixed sites and can provide insights for epidemiological risk assessment concerning extreme heat. Conclusions: Personal heat exposure research provides more valid and precise insights into how often people encounter heat conditions and when, where, to whom, and why these encounters occur. Published literature on personal heat exposure is limited to date, but existing studies point to opportunities to inform public health practice regarding extreme heat, particularly where fine-scale precision is needed to reduce health consequences of heat exposure. https://doi.org/10.1289/EHP556 PMID:28796630

Research on a new type of additive for CWS from low temperature pyrolysis tar

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu Guoguang; Wang Zuna

1997-12-31

In this paper, coal tar from flash pyrolysis of Ping Zhuang lignite with solid heat carrier was used as raw material, which was directly synthesized a new type of additive for coal water slurry (CWS) in the laboratory. The wetting heat between the lignite and distilled water and solution of additive has been determined. It is evident that the wetting heat between the lignite and distilled water is very high, up to 44.56 J/g, which is harmful to preparing CWS. The wetting heat between the lignite and a solution of additive is reduced, which is related to its characteristics suchmore » as surface properties, oxygen functional groups and structure. The effect of coal properties on preparing CWS has also been analyzed systematically. It is suggested that the concentration of CWS is regularly changed with oxygen content of coal based on moisture and ash content. It is emphasized that when the influence of macerals on slurriability of coal is observed, inherent properties of each maceral such as pore structure, porosity, oxygen functional groups, grindability must be tightly combined to evaluate comprehensively. The structural characteristics of the additive matches well the molecular structure and surface properties of the coal. It is seen by synthetic experiments that suitable a degree of sulphonating and condensation are beneficial to preparing CWS. The rheology and stability of CWS have also been investigated. The result indicates that the stability of CWS using the new type of additive is improved, and the production cost of the additive synthesized from low temperature pyrolysis coal tar can be reduced.« less

Fluid-flow pressure measurements and thermo-fluid characterization of a single loop two-phase passive heat transfer device

NASA Astrophysics Data System (ADS)

Ilinca, A.; Mangini, D.; Mameli, M.; Fioriti, D.; Filippeschi, S.; Araneo, L.; Roth, N.; Marengo, M.

2017-11-01

A Novel Single Loop Pulsating Heat Pipe (SLPHP), with an inner diameter of 2 mm, filled up with two working fluids (Ethanol and FC-72, Filling Ratio of 60%), is tested in Bottom Heated mode varying the heating power and the orientation. The static confinement diameter for Ethanol and FC-72, respectively 3.4 mm and 1.7mm, is above and slightly under the inner diameter of the tube. This is important for a better understanding of the working principle of the device very close to the limit between the Loop Thermosyphon and Pulsating Heat Pipe working modes. With respect to previous SLPHP experiments found in the literature, such device is designed with two transparent inserts mounted between the evaporator and the condenser allowing direct fluid flow visualization. Two highly accurate pressure transducers permit local pressure measurements just at the edges of one of the transparent inserts. Additionally, three heating elements are controlled independently, so as to vary the heating distribution at the evaporator. It is found that peculiar heating distributions promote the slug/plug flow motion in a preferential direction, increasing the device overall performance. Pressure measurements point out that the pressure drop between the evaporator and the condenser are related to the flow pattern. Furthermore, at high heat inputs, the flow regimes recorded for the two fluids are very similar, stressing that, when the dynamic effects start to play a major role in the system, the device classification between Loop Thermosyphon and Pulsating Heat Pipe is not that sharp anymore.

Using Direct Metal Deposition to Fabricate Mold Plates for an Injection Mold Machine Allowing for the Evaluation of Cost Effective Near-Sourcing Opportunities in Larger, High Volume Consumer Products

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duty, Chad E; Groh, Bill

2014-10-31

ORNL collaborated with Radio Systems Corporation to investigate additive manufacturing (AM) of mold plates for plastic injection molding by direct metal deposition. The team s modelling effort identified a 100% improvement in heat transfer through use of conformal cooling lines that could be built into the mold using a revolutionary design enabled by additive manufacturing. Using the newly installed laser deposition system at the ORNL Manufacturing Demonstration Facility (MDF) a stainless steel mold core was printed.

Local Thermometry of Neutral Modes on the Quantum Hall Edge

NASA Astrophysics Data System (ADS)

Hart, Sean; Venkatachalam, Vivek; Pfeiffer, Loren; West, Ken; Yacoby, Amir

2012-02-01

A system of electrons in two dimensions and strong magnetic fields can be tuned to create a gapped 2D system with one dimensional channels along the edge. Interactions among these edge modes can lead to independent transport of charge and heat, even in opposite directions. Measuring the chirality and transport properties of these charge and heat modes can reveal otherwise hidden structure in the edge. Here, we heat the outer edge of such a quantum Hall system using a quantum point contact. By placing quantum dots upstream and downstream along the edge of the heater, we can measure both the chemical potential and temperature of that edge to study charge and heat transport, respectively. We find that charge is transported exclusively downstream, but heat can be transported upstream when the edge has additional structure related to fractional quantum Hall physics.

Laser-induced heating integrated with a microfluidic platform for real-time DNA replication and detection

NASA Astrophysics Data System (ADS)

Hung, Min-Sheng; Ho, Chia-Chin; Chen, Chih-Pin

2016-08-01

This study developed a microfluidic platform for replicating and detecting DNA in real time by integrating a laser and a microfluidic device composed of polydimethylsiloxane. The design of the microchannels consisted of a laser-heating area and a detection area. An infrared laser was used as the heating source for DNA replication, and the laser power was adjusted to heat the solutions directly. In addition, strong biotin-avidin binding was used to capture and detect the replicated products. The biotin on one end was bound to avidin and anchored to the surface of the microchannels, whereas the biotin on the other end was bound to the quantum dots (Qdots). The results showed that the fluorescent intensity of the Qdots bound to the replicated products in the detection area increased with the number of thermal cycles created by the laser. When the number of thermal cycles was ≥10, the fluorescent intensity of the Qdots was directly detectable on the surface of the microchannels. The proposed method is more sensitive than detection methods entailing gel electrophoresis.

Characteristics of phase-change materials containing oxide nano-additives for thermal storage

PubMed Central

2012-01-01

In this study, the authors report the production of nanocomposite-enhanced phase-change materials (NEPCMs) using the direct-synthesis method by mixing paraffin with alumina (Al2O3), titania (TiO2), silica (SiO2), and zinc oxide (ZnO) as the experimental samples. Al2O3, TiO2, SiO2, and ZnO were dispersed into three concentrations of 1.0, 2.0, and 3.0 wt.%. Through heat conduction and differential scanning calorimeter experiments to evaluate the effects of varying concentrations of the nano-additives on the heat conduction performance and thermal storage characteristics of NEPCMs, their feasibility for use in thermal storage was determined. The experimental results demonstrate that TiO2 is more effective than the other additives in enhancing both the heat conduction and thermal storage performance of paraffin for most of the experimental parameters. Furthermore, TiO2 reduces the melting onset temperature and increases the solidification onset temperature of paraffin. This allows the phase-change heat to be applicable to a wider temperature range, and the highest decreased ratio of phase-change heat is only 0.46%, compared to that of paraffin. Therefore, this study demonstrates that TiO2, added to paraffin to form NEPCMs, has significant potential for enhancing the thermal storage characteristics of paraffin. PMID:23127224

Machinability of Al 6061 Deposited with Cold Spray Additive Manufacturing

NASA Astrophysics Data System (ADS)

Aldwell, Barry; Kelly, Elaine; Wall, Ronan; Amaldi, Andrea; O'Donnell, Garret E.; Lupoi, Rocco

2017-10-01

Additive manufacturing techniques such as cold spray are translating from research laboratories into more mainstream high-end production systems. Similar to many additive processes, finishing still depends on removal processes. This research presents the results from investigations into aspects of the machinability of aluminum 6061 tubes manufactured with cold spray. Through the analysis of cutting forces and observations on chip formation and surface morphology, the effect of cutting speed, feed rate, and heat treatment was quantified, for both cold-sprayed and bulk aluminum 6061. High-speed video of chip formation shows changes in chip form for varying material and heat treatment, which is supported by the force data and quantitative imaging of the machined surface. The results shown in this paper demonstrate that parameters involved in cold spray directly impact on machinability and therefore have implications for machining parameters and strategy.

Ice Generation and the Heat and Mass Transfer Phenomena of Introducing Water to a Cold Bath of Brine.

PubMed

Yun, Xiao; Quarini, Giuseppe L

2017-03-13

We demonstrate a method for the study of the heat and mass transfer and of the freezing phenomena in a subcooled brine environment. Our experiment showed that, under the proper conditions, ice can be produced when water is introduced to a bath of cold brine. To make ice form, in addition to having the brine and water mix, the rate of heat transfer must bypass that of mass transfer. When water is introduced in the form of tiny droplets to the brine surface, the mode of heat and mass transfer is by diffusion. The buoyancy stops water from mixing with the brine underneath, but as the ice grows thicker, it slows down the rate of heat transfer, making ice more difficult to grow as a result. When water is introduced inside the brine in the form of a flow, a number of factors are found to influence how much ice can form. Brine temperature and concentration, which are the driving forces of heat and mass transfer, respectively, can affect the water-to-ice conversion ratio; lower bath temperatures and brine concentrations encourage more ice to form. The flow rheology, which can directly affect both the heat and mass transfer coefficients, is also a key factor. In addition, the flow rheology changes the area of contact of the flow with the bulk fluid.

Experiment and modeling: Ignition of aluminum particles with a carbon dioxide laser

NASA Astrophysics Data System (ADS)

Mohan, Salil

Aluminum is a promising ingredient for high energy density compositions used in propulsion systems, explosives, and pyrotechnics. Aluminum powder fuel additives enable one to achieve higher combustion enthalpies and reaction temperatures. Therefore, to develop aluminum based novel and customized high density energetic materials, understanding of ignition and combustion kinetics of aluminum powders is required. In most practical systems, metal ignition and combustion occur in environments with rapidly changing temperatures and gas compositions. The kinetics of exothermic reactions in related energetic materials is commonly characterized by thermal analysis, where the heating rates are very low, on the order of 1--50 K/min. The extrapolation of the identified kinetics to the high heating rates is difficult and requires direct experimental verification. This difficulty led to development of new experimental approaches to directly characterize ignition kinetics for the heating rates in the range of 103--104 K/s. However, the practically interesting heating rates of 106 K/s range have not been achieved. This work is directed at development of an experimental technique and respective heat transfer model for studying ignition of aluminum and other micron-sized metallic particles at heating rates varied around 106 K/s. The experimental setup uses a focused CO2 laser as a heating source and a plate capacitor aerosolizer to feed the aluminum particles into the laser beam. The setup allows using different environment for particle aerosolization. The velocities of particles in the jet are in the range of 0.1 --0 3 m/s. For each selected jet velocity, the laser power is increased until the particles are observed to ignite. The ignition is detected optically using a digital camera and a photomultiplier. The ignition thresholds for spherical aluminum powder were measured at three different particle jet velocities, in air environment. A single particle heat transfer model was developed to describe the experiments. Experiments with different jet velocities in air environment were performed to validate the model. The interaction of the laser beam with particles is particle size dependent and a narrow range of particle sizes (around 3.4 microm) is heated most effectively. Therefore, the heat transfer model needs to be analyzed only for the particles with this specific size, which greatly simplifies the interpretation of experiments. Describing heating of a micron sized metal particle involves the transition regime heat transfer. A modified Fuchs model was used to describe the heat transfer in this study. In addition to dry air environment, the experimental technique was also used with other oxidizing environments, including O2, H2O, CO2 and mixtures thereof. It was observed that particle size capable of maintaining a vapor phase flame is a function of the environment. Arrhenius model kinetics parameters for Al ignition in O2, CO2 and H2O environments were determined.

Air/molten salt direct-contact heat-transfer experiment and economic analysis

NASA Astrophysics Data System (ADS)

Bohn, M. S.

1983-11-01

Direct-contact heat-transfer coefficients have been measured in a pilot-scale packed column heat exchanger for molten salt/air duty. Two types of commercial tower packings were tested: metal Raschig rings and initial Pall rings. Volumetric heat-transfer coefficients were measured and appeared to depend upon air flow but not on salt flow rate. An economic analysis was used to compare the cost-effectiveness of direct-contact heat exchange with finned-tube heat exchanger in this application. Incorporating the measured volumetric heat-transfer coefficients, a direct-contact system appeared to be from two to five times as cost-effective as a finned-tube heat exchanger, depending upon operating temperature. The large cost advantage occurs for higher operating temperatures (2700(0)C), where high rates of heat transfer and flexibility in materials choice give the cost advantage to the direct-contact heat exchanger.

A Report from the Thermal Science Research Center (TSRC)

NASA Technical Reports Server (NTRS)

Boyd, Ronald D.

1998-01-01

A vertical flow loop was designed and assembled to determine the local (circumferential and axial) and mean wall temperature distributions for single-phase and two-phase (subcooled and saturated) downward flow in both uniformly-heated and single-side heated vertical channels. Freon-11 was used as the working fluid in order to directly relate and compare the results with a previous experimental campaign which employed this same working fluid. For a given steady-state experiment, the following parameters were held constant: (1) exit pressure, (2) inlet temperature, and (3) mass velocity. For a given configuration of the 2.2 m long cylindrical channel test section, which had a 1.2 m long heated section, the applied heat rate was varied from zero through successive quasi-steady states to a level which corresponded to localized film boiling in the test section. The measurements showed that the boiling curve changes significantly at higher mass velocities with respect to both the circumferential and axial directions. The slope of the boiling curve changes in a non-monotonic fashion with respect to the circumferential directions. The slope of the boiling curve changes in a non-monotonic fashion with respect to the circumferential direction. The measurements point to the existence of a dry-out phenomenon occurring at multiple levels of the applied heat for the single-side heated channel. In comparing the heat transfer for horizontal channel flow with a vertically downward flow, the results show that significantly lower heat transfer occurs in the horizontal flow. However, this trend reverses as both the Reynolds number and the applied heat rate increase. Both the Liu-Winterton and Shah correlations were compared with the experimental data. The Shah correlation predicted the uniformly heated tube data better. When a thermal hydraulic diameter approach was used for the single-side heated case, the data at upstream locations for Z/L less than 0.5 was bounded above by the Liu-Winterton correlation and below by the Shah correlation. At Z/L = 0.5, the Shah correlation bounded the data; and for Z/L greater than 0.5, both correlations overpredicted the data with the Shah correlation being closest to the data. The present results indicate that additional correlational development is needed. In addressing some of the advanced space thermal management objectives concerning accommodating high heat fluxes in non-uniformly heated systems, a large battery of experiments 88 have been completed where local two-dimensional wall temperature variations were measured for both single-phase and two-phase flow in a single-side heated circular tube. As noted above, the results show significant axial and circumferential variations. Accurately accounting for such variations can result in optimized future advanced space, enhanced (high heat flux) thermal management systems.

Oscillating side-branch enhancements of thermoacoustic heat exchangers

DOEpatents

Swift, Gregory W.

2003-05-13

A regenerator-based engine or refrigerator has a regenerator with two ends at two different temperatures, through which a gas oscillates at a first oscillating volumetric flow rate in the direction between the two ends and in which the pressure of the gas oscillates, and first and second heat exchangers, each of which is at one of the two different temperatures. A dead-end side branch into which the gas oscillates has compliance and is connected adjacent to one of the ends of the regenerator to form a second oscillating gas flow rate additive with the first oscillating volumetric flow rate, the compliance having a volume effective to provide a selected total oscillating gas volumetric flow rate through the first heat exchanger. This configuration enables the first heat exchanger to be configured and located to better enhance the performance of the heat exchanger rather than being confined to the location and configuration of the regenerator.

Power density of piezoelectric transformers improved using a contact heat transfer structure.

PubMed

Shao, Wei Wei; Chen, Li Juan; Pan, Cheng Liang; Liu, Yong Bin; Feng, Zhi Hua

2012-01-01

Based on contact heat transfer, a novel method to increase power density of piezoelectric transformers is proposed. A heat transfer structure is realized by directly attaching a dissipater to the piezoelectric transformer plate. By maintaining the vibration mode of the transformer and limiting additional energy losses from the contact interface, an appropriate design can improve power density of the transformer on a large scale, resulting from effective suppression of its working temperature rise. A prototype device was fabricated from a rectangular piezoelectric transformer, a copper heat transfer sheet, a thermal grease insulation pad, and an aluminum heat radiator. The experimental results show the transformer maintains a maximum power density of 135 W/cm(3) and an efficiency of 90.8% with a temperature rise of less than 10 °C after more than 36 h, without notable changes in performance. © 2012 IEEE

Enhancing Convective Heat Transfer over a Surrogate Photovoltaic Panel

NASA Astrophysics Data System (ADS)

Fouladi, Fama

This research is particularly focused on studying heat transfer enhancement of a photovoltaic (PV) panel by putting an obstacle at the panel's windward edge. The heat transfer enhancement is performed by disturbing the airflow over the surface and increasing the heat and momentum transfer. Different objects such as triangular, square, rectangular, and discrete rectangular ribs and partial grids were applied at the leading edge of a surrogate PV panel and flow and the heat transfer of the panel are investigated experimentally. This approach was selected to expand understanding of effect of these different objects on the flow and turbulence structures over a flat surface by analyzing the flow comprehensively. It is observed that, a transverse object at the plate's leading edge would cause some flow blockage in the streamwise direction, but at the same time creates some velocity in the normal and cross stream directions. In addition to that, the obstacle generates some turbulence over the surface which persists for a long downstream distance. Also, among all studied objects, discrete rectangular ribs demonstrate the highest heat transfer rate enhancement (maximum Nu/Nu0 of 1.5). However, ribs with larger gap ratios are observed to be more effective at enhancing the heat transfer augmentation at closer distances to the rib, while at larger downstream distances from the rib, discrete ribs with smaller gap ratios are more effective. Furthermore, this work attempted to recognize the most influential flow parameters on the heat transfer enhancement of the surface. It is seen that the flow structure over a surface downstream of an object (flow separation-reattachment behaviour) has a significant effect on the heat transfer enhancement trend. Also, turbulence intensities are the most dominant parameters in enhancing the heat transfer rate from the surface; however, flow velocity (mostly normal velocity) is also an important factor.

Good feeling of living in the earth

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wolf, R.

1978-12-01

Underground houses combine energy savings and a comfortable lifestyle that leaves more land undisturbed and works with rather than against nature. Soil moderates and delays temperature fluctuations, leaving the heating system with a steady temperature that is much more efficient than the best insulated above-ground building. The combination of passive solar heating and underground construction suggests the possibility of an entirely new direction for future housing. Passive solar heating is appropriate because of the soil shield and the thermal mass provided by reinforced concrete. Both construction and operating costs are lower than conventional housing. Three styles: bermed, below grade, andmore » dug-in are available. Several sources of additional information are listed.« less

Intra-binary Shock Heating of Black Widow Companions

NASA Astrophysics Data System (ADS)

Romani, Roger W.; Sanchez, Nicolas

2016-09-01

The low-mass companions of evaporating binary pulsars (black widows and similar) are strongly heated on the side facing the pulsar. However, in high-quality photometric and spectroscopic data, the heating pattern does not match that expected for direct pulsar illumination. Here we explore a model where the pulsar power is intercepted by an intra-binary shock (IBS) before heating the low-mass companion. We develop a simple analytic model and implement it in the popular “ICARUS” light curve code. The model is parameterized by the wind momentum ratio β and the companion wind speed {f}v{v}{{orb}}, and assumes that the reprocessed pulsar wind emits prompt particles or radiation to heat the companion surface. We illustrate an interesting range of light curve asymmetries controlled by these parameters. The code also computes the IBS synchrotron emission pattern, and thus can model black widow X-ray light curves. As a test, we apply the results to the high-quality asymmetric optical light curves of PSR J2215+5135; the resulting fit gives a substantial improvement upon direct heating models and produces an X-ray light curve consistent with that seen. The IBS model parameters imply that at the present loss rate, the companion evaporation has a characteristic timescale of {τ }{{evap}}≈ 150 Myr. Still, the model is not fully satisfactory, indicating that there are additional unmodeled physical effects.

Liquid methane gelled with methanol and water reduces rate of nitrogen absorption

NASA Technical Reports Server (NTRS)

Vanderwall, E. M.

1972-01-01

Dilution of gelant vapor with inert carrier gas accomplishes gelation. Mixture is injected through heated tube and orifice into liquid methane for immediate condensation within bulk of liquid. Direct dispersion of particles in liquid avoids condensation on walls of vessel and eliminates additional mixing.

Thermocapillary flow with evaporation and condensation and its effect on liquid retention in low-G fluid acquisition devices

NASA Technical Reports Server (NTRS)

Schmidt, George R.

1994-01-01

The steady motion, thermal and free surface behavior of a volatile, wetting liquid in microgravity are studied using scaling and numerical techniques. The objective is to determine whether the thermocapillary and two-phase convection arising from thermodynamic nonequilibrium along the porous surfaces of spacecraft liquid acquisition devices could cause the retention failures observed with liquid hydrogen and heated vapor pressurant. Why these devices seem immune to retention loss when pressurized with heated helium or heated directly through the porous structure was also examined. Results show that highly wetting fluids exhibit large negative and positive dynamic pressure gradients towards the meniscus interline when superheated and subcooled, respectively. With superheating, the pressure variation and recoil force arising from liquid/vapor phase change exert the same influence on surface morphology and promote retention. With subcooling, however, the pressure distribution produces a suction that degrades mechanical equilibrium of the surface. This result indicates that thermocapillary-induced deformation arising from subcooling and condensation is the likely cause for retention loss. In addition, increasing the level of nonequilibrium by reducing accommodation coefficient suppresses deformation and explains why this failure mode does not occur in instances of direct screen heating or pressurization with a heated inert gas.

Effect of force fields on pool boiling flow patterns in normal and reduced gravity

NASA Astrophysics Data System (ADS)

di Marco, P.; Grassi, W.

2009-05-01

This paper reports the observations of boiling flow patterns in FC-72, performed during a microgravity experiment, recently flown aboard of Foton-M2 satellite, in some instances with the additional aid of an electrostatic field to replace the buoyancy force. The heater consisted of a flat plate, 20 × 20 mm2, directly heated by direct current. Several levels of liquid subcooling (from 20 to 6 K) and heat fluxes up to 200 kW/m2 were tested. A complete counterpart test, carried out on ground before the mission, allowed direct comparison with terrestrial data. The void fraction in microgravity revealed much larger than in normal gravity condition: this may be attributed to increased bubble coalescence that hinders vapor condensation in the bulk of the subcooled fluid. In several cases, an oscillatory boiling behavior was detected, leading to periodical variation of average wall overheating of some degrees. The electric field confirmed to be very effective, even at low values of applied voltage, in reducing bubble size, thus improving their condensation rate in the bulk fluid, and in enhancing heat transfer performance, suppressing the boiling oscillations and preventing surface dryout.

Heat transfer and pressure drop measurements in an air/molten salt direct-contact heat exchanger

NASA Astrophysics Data System (ADS)

Bohn, Mark S.

1988-11-01

This paper presents a comparison of experimental data with a recently published model of heat exchange in irrigated packed beds. Heat transfer and pressure drop were measured in a 150 mm (ID) column with a 610 mm bed of metal Pall rings. Molten nitrate salt and preheated air were the working fluids with a salt inlet temperature of approximately 440 C and air inlet temperatures of approximately 230 C. A comparison between the experimental data and the heat transfer model is made on the basis of heat transfer from the salt. For the range of air and salt flow rates tested, 0.3 to 1.2 kg/sq m/s air flow and 6 to 18 kg/sq m/s salt flow, the data agree with the model within 22 percent standard deviation. In addition, a model for the column pressure drop was validated, agreeing with the experimental data within 18 percent standard deviation over the range of column pressure drop from 40 to 1250 Pa/m.

The influence of PM2.5 coal power plant emissions on environment PM2.5 in Jilin Province, China

NASA Astrophysics Data System (ADS)

Sun, Ye; Li, Zhi; Zhang, Dan; Zhang, He; Zhang, Huafei

2018-02-01

In recent years, in the Northeast of China, the heating period comes with large range of haze weather. All the units of coal power plants in Jilin Province have completed the cogeneration reformation; they provide local city heat energy. Many people believe that coal power plants heating caused the heavy haze. In is paper, by compared concentration of PM2.5 in environment in heating period and non heating period, meanwhile the capacity of local coal power plants, conclude that the PM2.5 emission of coal power plants not directly cause the heavy haze in Changchun and Jilin in the end of October and early November. In addition, the water-soluble iron composition of PM2.5 coal power plant emissions is compared with environment, which further proves that the heating supply in coal power plants is not the cause of high concentration of PM2.5 in Jilin province.

Bessel Fourier orientation reconstruction: an analytical EAP reconstruction using multiple shell acquisitions in diffusion MRI.

PubMed

Hosseinbor, Ameer Pasha; Chung, Moo K; Wu, Yu-Chien; Alexander, Andrew L

2011-01-01

The estimation of the ensemble average propagator (EAP) directly from q-space DWI signals is an open problem in diffusion MRI. Diffusion spectrum imaging (DSI) is one common technique to compute the EAP directly from the diffusion signal, but it is burdened by the large sampling required. Recently, several analytical EAP reconstruction schemes for multiple q-shell acquisitions have been proposed. One, in particular, is Diffusion Propagator Imaging (DPI) which is based on the Laplace's equation estimation of diffusion signal for each shell acquisition. Viewed intuitively in terms of the heat equation, the DPI solution is obtained when the heat distribution between temperatuere measurements at each shell is at steady state. We propose a generalized extension of DPI, Bessel Fourier Orientation Reconstruction (BFOR), whose solution is based on heat equation estimation of the diffusion signal for each shell acquisition. That is, the heat distribution between shell measurements is no longer at steady state. In addition to being analytical, the BFOR solution also includes an intrinsic exponential smootheing term. We illustrate the effectiveness of the proposed method by showing results on both synthetic and real MR datasets.

Thick or Thin Ice Shell on Europa?

NASA Technical Reports Server (NTRS)

2007-01-01

Scientists are all but certain that Europa has an ocean underneath its icy surface, but they do not know how thick this ice might be. This artist concept illustrates two possible cut-away views through Europa's ice shell. In both, heat escapes, possibly volcanically, from Europa's rocky mantle and is carried upward by buoyant oceanic currents. If the heat from below is intense and the ice shell is thin enough (left), the ice shell can directly melt, causing what are called 'chaos' on Europa, regions of what appear to be broken, rotated and tilted ice blocks. On the other hand, if the ice shell is sufficiently thick (right), the less intense interior heat will be transferred to the warmer ice at the bottom of the shell, and additional heat is generated by tidal squeezing of the warmer ice. This warmer ice will slowly rise, flowing as glaciers do on Earth, and the slow but steady motion may also disrupt the extremely cold, brittle ice at the surface. Europa is no larger than Earth's moon, and its internal heating stems from its eccentric orbit about Jupiter, seen in the distance. As tides raised by Jupiter in Europa's ocean rise and fall, they may cause cracking, additional heating and even venting of water vapor into the airless sky above Europa's icy surface. (Artwork by Michael Carroll.)

Deformation behavior of additively manufactured GP1 stainless steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clausen, B.; Brown, D. W.; Carpenter, J. S.

In-situ neutron diffraction measurements were performed in this paper during heat-treating and uniaxial loading of additively manufactured (AM) GP1 material. Although the measured chemical composition of the GP1 powder falls within the composition specifications of 17-4 PH steel, a fully martensitic alloy in the wrought condition, the crystal structure of the as-built GP1 material is fully austenitic. Chemical analysis of the as-built material shows high oxygen and nitrogen content, which then significantly decreased after heat-treating in a vacuum furnace at 650 °C for one hour. Significant austenite-to-martensite phase transformation is observed during compressive and tensile loading of the as-built andmore » heat-treated material with accompanied strengthening as martensite volume fraction increases. During loading, the initial average phase stress state in the martensite is hydrostatic compression independent of the loading direction. Finally, preferred orientation transformation in austenite and applied load accommodation by variant selection in martensite are observed via measurements of the texture development.« less

Patterning of ultrathin polymethylmethacrylate films by in-situ photodirecting of the Marangoni flow

NASA Astrophysics Data System (ADS)

Elashnikov, Roman; Fitl, Premysl; Svorcik, Vaclav; Lyutakov, Oleksiy

2017-02-01

Laser heating and Marangoni flow result in the formation of surface structures with different geometries and shape on thin polymer films. By laser beam irradiation combined with a sample movement the solid polymethylmethacrylate (PMMA) films are heated and undergo phase transition which leads to a material flow. Since the laser beam has a non-linear distribution of energy, the PMMA film is heated inhomogeneously and a surface tension gradient in a lateral direction is introduced. During this procedure additional phenomena such as "reversible" or cyclic polymer flow also take place. The careful choice of experimental conditions enables the preparation of patterns with sophisticated geometries and with hierarchical pattern organization. Depending on initial PMMA film thickness and speed of the sample movement line arrays are created, which can subsequently be transformed into the crimped lines or system of circular holes. In addition, the introduction of a constant acceleration in the sample movement or a laser beam distortion enables the preparation of regularly crimped lines, ordered hexagonal holes or overlapped plates.

Deformation behavior of additively manufactured GP1 stainless steel

DOE PAGES

Clausen, B.; Brown, D. W.; Carpenter, J. S.; ...

2017-04-22

In-situ neutron diffraction measurements were performed in this paper during heat-treating and uniaxial loading of additively manufactured (AM) GP1 material. Although the measured chemical composition of the GP1 powder falls within the composition specifications of 17-4 PH steel, a fully martensitic alloy in the wrought condition, the crystal structure of the as-built GP1 material is fully austenitic. Chemical analysis of the as-built material shows high oxygen and nitrogen content, which then significantly decreased after heat-treating in a vacuum furnace at 650 °C for one hour. Significant austenite-to-martensite phase transformation is observed during compressive and tensile loading of the as-built andmore » heat-treated material with accompanied strengthening as martensite volume fraction increases. During loading, the initial average phase stress state in the martensite is hydrostatic compression independent of the loading direction. Finally, preferred orientation transformation in austenite and applied load accommodation by variant selection in martensite are observed via measurements of the texture development.« less

Aircraft skin cooling system for thermal management of onboard high power electronic equipment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hashemi, A.; Dyson, E.

1996-12-31

Integration of high-power electronic devices into existing aircraft, while minimizing the impact of additional heat load on the environmental control system of the aircraft, requires innovative approaches. One such approach is to reject heat through the aircraft skin by use of internal skin ducts with enhanced surfaces. This approach requires a system level consideration of the effect of cooling ducts, inlets and outlets on the performance of the electronic equipment and effectiveness of the heat rejection system. This paper describes the development of a system-level model to evaluate the performance of electronic equipment in an aircraft cabin and heat rejectionmore » through the skin. In this model, the outer surface of the fuselage is treated as a heat exchanger. Hot air from an equipment exhaust plenum is drawn into a series of baffled ducts within the fuselage support structure, where the heat is rejected, and then recirculated into the cabin. The cooler air form the cabin is then drawn into the electronic equipment. The aircraft air conditioning unit is also modeled to provide chilled air directly into the cabin. In addition, this paper describes a series of tests which were performed to verify the model assumptions for heat dissipation from and air flow through the equipment. The tests were performed using the actual electronic equipment in a representative cabin configuration. Results indicate very good agreement between the analytical calculations for the design point and model predictions.« less

Prediction modeling of physiological responses and human performance in the heat with application to space operations

NASA Technical Reports Server (NTRS)

Pandolf, Kent B.; Stroschein, Leander A.; Gonzalez, Richard R.; Sawka, Michael N.

1994-01-01

This institute has developed a comprehensive USARIEM heat strain model for predicting physiological responses and soldier performance in the heat which has been programmed for use by hand-held calculators, personal computers, and incorporated into the development of a heat strain decision aid. This model deals directly with five major inputs: the clothing worn, the physical work intensity, the state of heat acclimation, the ambient environment (air temperature, relative humidity, wind speed, and solar load), and the accepted heat casualty level. In addition to predicting rectal temperature, heart rate, and sweat loss given the above inputs, our model predicts the expected physical work/rest cycle, the maximum safe physical work time, the estimated recovery time from maximal physical work, and the drinking water requirements associated with each of these situations. This model provides heat injury risk management guidance based on thermal strain predictions from the user specified environmental conditions, soldier characteristics, clothing worn, and the physical work intensity. If heat transfer values for space operations' clothing are known, NASA can use this prediction model to help avoid undue heat strain in astronauts during space flight.

Energy budget closure and field scale estimation of canopy energy storage with increased and sustained turbulence

USDA-ARS?s Scientific Manuscript database

Eddy Covariance (EC) is widely used for direct, non-invasive observations of land-atmosphere energy and mass fluxes. However, EC observations of available energy fluxes are usually less than fluxes inferred from radiometer and soil heat flux observations; thus introducing additional uncertainty in u...

21 CFR 801.420 - Hearing aid devices; professional and patient labeling.

Code of Federal Regulations, 2014 CFR

2014-04-01

... damage the hearing aid, such as dropping, immersing, or exposing the hearing aid to excessive heat. (vii... strongly discouraged. children with hearing loss In addition to seeing a physician for a medical evaluation, a child with a hearing loss should be directed to an audiologist for evaluation and rehabilitation...

Direct-contact closed-loop heat exchanger

DOEpatents

Berry, Gregory F.; Minkov, Vladimir; Petrick, Michael

1984-01-01

A high temperature heat exchanger with a closed loop and a heat transfer liquid within the loop, the closed loop having a first horizontal channel with inlet and outlet means for providing direct contact of a first fluid at a first temperature with the heat transfer liquid, a second horizontal channel with inlet and outlet means for providing direct contact of a second fluid at a second temperature with the heat transfer liquid, and means for circulating the heat transfer liquid.

Comparing Multiple Evapotranspiration-calculating Methods, Including Eddy Covariance and Surface Renewal, Using Empirical Measurements from Alfalfa Fields in the Sacramento-San Joaquin River Delta

NASA Astrophysics Data System (ADS)

Clay, J.; Kent, E. R.; Leinfelder-Miles, M.; Lambert, J. J.; Little, C.; Paw U, K. T.; Snyder, R. L.

2016-12-01

Eddy covariance and surface renewal measurements were used to estimate evapotranspiration (ET) over a variety of crop fields in the Sacramento-San Joaquin River Delta during the 2016 growing season. However, comparing and evaluating multiple measurement systems and methods for determining ET was focused upon at a single alfalfa site. The eddy covariance systems included two systems for direct measurement of latent heat flux: one using a separate sonic anemometer and an open path infrared gas analyzer and another using a combined system (Campbell Scientific IRGASON). For these methods, eddy covariance was used with measurements from the Campbell Scientific CSAT3, the LI-COR 7500a, the Campbell Scientific IRGASON, and an additional R.M. Young sonic anemometer. In addition to those direct measures, the surface renewal approach included several energy balance residual methods in which net radiation, ground heat flux, and sensible heat flux (H) were measured. H was measured using several systems and different methods, including using multiple fast-response thermocouple measurements and using the temperatures measured by the sonic anemometers. The energy available for ET was then calculated as the residual of the surface energy balance equation. Differences in ET values were analyzed between the eddy covariance and surface renewal methods, using the IRGASON-derived values of ET as the standard for accuracy.

Simulated Seasonal Spatio-Temporal Patterns of Soil Moisture, Temperature, and Net Radiation in a Deciduous Forest

NASA Technical Reports Server (NTRS)

Ballard, Jerrell R., Jr.; Howington, Stacy E.; Cinnella, Pasquale; Smith, James A.

2011-01-01

The temperature and moisture regimes in a forest are key components in the forest ecosystem dynamics. Observations and studies indicate that the internal temperature distribution and moisture content of the tree influence not only growth and development, but onset and cessation of cambial activity [1], resistance to insect predation[2], and even affect the population dynamics of the insects [3]. Moreover, temperature directly affects the uptake and metabolism of population from the soil into the tree tissue [4]. Additional studies show that soil and atmospheric temperatures are significant parameters that limit the growth of trees and impose treeline elevation limitation [5]. Directional thermal infrared radiance effects have long been observed in natural backgrounds [6]. In earlier work, we illustrated the use of physically-based models to simulate directional effects in thermal imaging [7-8]. In this paper, we illustrated the use of physically-based models to simulate directional effects in thermal, and net radiation in a adeciduous forest using our recently developed three-dimensional, macro-scale computational tool that simulates the heat and mass transfer interaction in a soil-root-stem systems (SRSS). The SRSS model includes the coupling of existing heat and mass transport tools to stimulate the diurnal internal and external temperatures, internal fluid flow and moisture distribution, and heat flow in the system.

Hot spot heat transfer - Its application to Venus and implications to Venus and earth

NASA Technical Reports Server (NTRS)

Morgan, P.; Phillips, R. J.

1983-01-01

Using a model that gives a relationship between surface elevation, lithospheric thickness, and heat flux, the hot spot heat loss mechanism is tested for Venus. The mechanism is found to readily explain the predicted heat loss of the planet with a modest number of hot spots (of the order of 35). Lithospheric thickness variations can explain approximately 93 percent of the mapped topography of Venus. Above a radius of 6053 km, additional compensation is required, and this can be effected by incorporating a variable thickness crust into the model. If it is assumed that the crust is generated on the crests of the hot spots, probably by processes associated with volcanism, the model is consistent with nearly 99 percent of the mapped topography of Venus. In addition, the model is basically consistent with available gravity data and interpretations that suggest compensated topography and great depths of compensation (100-1000 km) for the midlatitudes of the planet. It is thought that the approximately 1 percent of the topography not explained by hot spot crustal generation is compensated at a shallower depth primarily by variations in crustal thickness that are not directly related to hot spot volcanism.

Direct-contact closed-loop heat exchanger

DOEpatents

Berry, G.F.; Minkov, V.; Petrick, M.

1981-11-02

A high temperature heat exchanger is disclosed which has a closed loop and a heat transfer liquid within the loop, the closed loop having a first horizontal channel with inlet and outlet means for providing direct contact of a first fluid at a first temperature with the heat transfer liquid, a second horizontal channel with inlet and outlet means for providing direct contact of a second fluid at a second temperature with the heat transfer liquid, and means for circulating the heat transfer liquid.

Additive manufacturing with polypropylene microfibers.

PubMed

Haigh, Jodie N; Dargaville, Tim R; Dalton, Paul D

2017-08-01

The additive manufacturing of small diameter polypropylene microfibers is described, achieved using a technique termed melt electrospinning writing. Sequential fiber layering, which is important for accurate three-dimensional fabrication, was achieved with the smallest fiber diameter of 16.4±0.2μm obtained. The collector speed, temperature and melt flow rate to the nozzle were optimized for quality and minimal fiber pulsing. Of particular importance to the success of this method is appropriate heating of the collector plate, so that the electrostatically drawn filament adheres during the direct-writing process. By demonstrating the direct-writing of polypropylene, new applications exploiting the favorable mechanical, stability and biocompatible properties of this polymer are envisaged. Copyright © 2017. Published by Elsevier B.V.

Large Scale Flame Spread Environmental Characterization Testing

NASA Technical Reports Server (NTRS)

Clayman, Lauren K.; Olson, Sandra L.; Gokoghi, Suleyman A.; Brooker, John E.; Ferkul, Paul V.; Kacher, Henry F.

2013-01-01

Under the Advanced Exploration Systems (AES) Spacecraft Fire Safety Demonstration Project (SFSDP), as a risk mitigation activity in support of the development of a large-scale fire demonstration experiment in microgravity, flame-spread tests were conducted in normal gravity on thin, cellulose-based fuels in a sealed chamber. The primary objective of the tests was to measure pressure rise in a chamber as sample material, burning direction (upward/downward), total heat release, heat release rate, and heat loss mechanisms were varied between tests. A Design of Experiments (DOE) method was imposed to produce an array of tests from a fixed set of constraints and a coupled response model was developed. Supplementary tests were run without experimental design to additionally vary select parameters such as initial chamber pressure. The starting chamber pressure for each test was set below atmospheric to prevent chamber overpressure. Bottom ignition, or upward propagating burns, produced rapid acceleratory turbulent flame spread. Pressure rise in the chamber increases as the amount of fuel burned increases mainly because of the larger amount of heat generation and, to a much smaller extent, due to the increase in gaseous number of moles. Top ignition, or downward propagating burns, produced a steady flame spread with a very small flat flame across the burning edge. Steady-state pressure is achieved during downward flame spread as the pressure rises and plateaus. This indicates that the heat generation by the flame matches the heat loss to surroundings during the longer, slower downward burns. One heat loss mechanism included mounting a heat exchanger directly above the burning sample in the path of the plume to act as a heat sink and more efficiently dissipate the heat due to the combustion event. This proved an effective means for chamber overpressure mitigation for those tests producing the most total heat release and thusly was determined to be a feasible mitigation strategy to incorporate into the microgravity experiment.

Comfortable, high-efficiency heat pump with desiccant-coated, water-sorbing heat exchangers

NASA Astrophysics Data System (ADS)

Tu, Y. D.; Wang, R. Z.; Ge, T. S.; Zheng, X.

2017-01-01

Comfortable, efficient, and affordable heating, ventilation, and air conditioning systems in buildings are highly desirable due to the demands of energy efficiency and environmental friendliness. Traditional vapor-compression air conditioners exhibit a lower coefficient of performance (COP) (typically 2.8-3.8) owing to the cooling-based dehumidification methods that handle both sensible and latent loads together. Temperature- and humidity-independent control or desiccant systems have been proposed to overcome these challenges; however, the COP of current desiccant systems is quite small and additional heat sources are usually needed. Here, we report on a desiccant-enhanced, direct expansion heat pump based on a water-sorbing heat exchanger with a desiccant coating that exhibits an ultrahigh COP value of more than 7 without sacrificing any comfort or compactness. The pump’s efficiency is doubled compared to that of pumps currently used in conventional room air conditioners, which is a revolutionary HVAC breakthrough. Our proposed water-sorbing heat exchanger can independently handle sensible and latent loads at the same time. The desiccants adsorb moisture almost isothermally and can be regenerated by condensation heat. This new approach opens up the possibility of achieving ultrahigh efficiency for a broad range of temperature- and humidity-control applications.

Comfortable, high-efficiency heat pump with desiccant-coated, water-sorbing heat exchangers.

PubMed

Tu, Y D; Wang, R Z; Ge, T S; Zheng, X

2017-01-12

Comfortable, efficient, and affordable heating, ventilation, and air conditioning systems in buildings are highly desirable due to the demands of energy efficiency and environmental friendliness. Traditional vapor-compression air conditioners exhibit a lower coefficient of performance (COP) (typically 2.8-3.8) owing to the cooling-based dehumidification methods that handle both sensible and latent loads together. Temperature- and humidity-independent control or desiccant systems have been proposed to overcome these challenges; however, the COP of current desiccant systems is quite small and additional heat sources are usually needed. Here, we report on a desiccant-enhanced, direct expansion heat pump based on a water-sorbing heat exchanger with a desiccant coating that exhibits an ultrahigh COP value of more than 7 without sacrificing any comfort or compactness. The pump's efficiency is doubled compared to that of pumps currently used in conventional room air conditioners, which is a revolutionary HVAC breakthrough. Our proposed water-sorbing heat exchanger can independently handle sensible and latent loads at the same time. The desiccants adsorb moisture almost isothermally and can be regenerated by condensation heat. This new approach opens up the possibility of achieving ultrahigh efficiency for a broad range of temperature- and humidity-control applications.

Hot dry rock geothermal energy: A renewable energy resource that is ready for development now

NASA Astrophysics Data System (ADS)

Brown, D. W.; Potter, R. M.; Myers, C. W.

Hot dry rock (HDR) geothermal energy, which utilizes the natural heat contained in the earth's crust, is a very large and well-distributed resource of nonpolluting, and essentially renewable, energy that is available globally. Its use could help mitigate climatic change and reduce acid rain, two of the major environmental consequences of our ever-increasing use of fossil fuels for heating and power generation. In addition, HDR, as a readily available source of indigenous energy, can reduce our nations's dependence on imported oil, enhancing national security and reducing our trade deficit. On a national scale we can begin to develop this new source, using it directly for power generation or for direct-heat applications, or indirectly in hybrid geothermal/fossil-fuel power plants. In the HDR concept, which has been demonstrated in the field in two different applications and flow-tested for periods up to one year, heat is recovered from the earth by pressurized water in a closed-loop circulation system. As a consequence, minimal effluents are released to the atmosphere, and no wastes are produced. This paper describes the nature of the HDR resource and the technology required to implement the heat-mining concept. An assessment of the requirements for establishing HDR feasibility is presented in the context of providing a commercially competitive energy source.

Performance evaluation on an air-cooled heat exchanger for alumina nanofluid under laminar flow.

PubMed

Teng, Tun-Ping; Hung, Yi-Hsuan; Teng, Tun-Chien; Chen, Jyun-Hong

2011-08-09

This study analyzes the characteristics of alumina (Al2O3)/water nanofluid to determine the feasibility of its application in an air-cooled heat exchanger for heat dissipation for PEMFC or electronic chip cooling. The experimental sample was Al2O3/water nanofluid produced by the direct synthesis method at three different concentrations (0.5, 1.0, and 1.5 wt.%). The experiments in this study measured the thermal conductivity and viscosity of nanofluid with weight fractions and sample temperatures (20-60°C), and then used the nanofluid in an actual air-cooled heat exchanger to assess its heat exchange capacity and pressure drop under laminar flow. Experimental results show that the nanofluid has a higher heat exchange capacity than water, and a higher concentration of nanoparticles provides an even better ratio of the heat exchange. The maximum enhanced ratio of heat exchange and pressure drop for all the experimental parameters in this study was about 39% and 5.6%, respectively. In addition to nanoparticle concentration, the temperature and mass flow rates of the working fluid can affect the enhanced ratio of heat exchange and pressure drop of nanofluid. The cross-section aspect ratio of tube in the heat exchanger is another important factor to be taken into consideration.

Performance evaluation on an air-cooled heat exchanger for alumina nanofluid under laminar flow

PubMed Central

2011-01-01

This study analyzes the characteristics of alumina (Al2O3)/water nanofluid to determine the feasibility of its application in an air-cooled heat exchanger for heat dissipation for PEMFC or electronic chip cooling. The experimental sample was Al2O3/water nanofluid produced by the direct synthesis method at three different concentrations (0.5, 1.0, and 1.5 wt.%). The experiments in this study measured the thermal conductivity and viscosity of nanofluid with weight fractions and sample temperatures (20-60°C), and then used the nanofluid in an actual air-cooled heat exchanger to assess its heat exchange capacity and pressure drop under laminar flow. Experimental results show that the nanofluid has a higher heat exchange capacity than water, and a higher concentration of nanoparticles provides an even better ratio of the heat exchange. The maximum enhanced ratio of heat exchange and pressure drop for all the experimental parameters in this study was about 39% and 5.6%, respectively. In addition to nanoparticle concentration, the temperature and mass flow rates of the working fluid can affect the enhanced ratio of heat exchange and pressure drop of nanofluid. The cross-section aspect ratio of tube in the heat exchanger is another important factor to be taken into consideration. PMID:21827644

Geothermal Heat Flux: Linking Deep Earth's Interior and the Dynamics of Large-Scale Ice Sheets

NASA Astrophysics Data System (ADS)

Rogozhina, Irina; Vaughan, Alan

2014-05-01

Regions covered by continental-scale ice sheets have the highest degree of uncertainty in composition and structure of the crust and lithospheric mantle, compounded by the poorest coverage on Earth of direct heat flow measurements. In addition to challenging conditions that make direct measurements and geological survey difficult Greenland and Antarctica are known to be geologically complex. Antarctica in particular is marked by two lithospherically distinct zones. In contrast to young and thin lithosphere of West Antarctica, East Antarctica is a collage of thick Precambrian fragments of Gondwana and earlier supercontinents. However, recent observations and modeling studies have detected large systems of subglacial lakes extending beneath much of the East Antarctic ice sheet base that have been linked to anomalously elevated heat flow. Outcrop samples from the rift margin with Australia (Prydz Bay) have revealed highly radiogenic Cambrian granite intrusives that are implicated in regional increase of crustal heat flux by a factor of two to three compared to the estimated continental background. Taken together, these indicate high variability of heat flow and properties of rocks across Antarctica. Similar conclusions have been made based on direct measurements and observations of the Greenland ice sheet. Airborne ice-penetrating radar and deep ice core projects show very high rates of basal melt for parts of the ice sheet in northern and central Greenland that have been explained by abnormally high heat flux. Archaean in age, the Greenland lithosphere was significantly reworked during the Early Proterozoic. In this region, the interpretation of independent geophysical data is complicated by Proterozoic and Phanerozoic collision zones, compounded by strong thermochemical effects of rifting along the western and eastern continental margins between 80 and 25 million years ago. In addition, high variability of heat flow and thermal lithosphere structure in central Greenland results from the remanent effects of an Early Cenozoic passage of the lithosphere above the Iceland mantle plume that is implicated in strong thermochemical erosion of the lithosphere and significant long-term effects on the present-day subglacial heat flow pattern and thermodynamic state of the Greenland ice sheet. These observations and our modeling results (Petrunin et al., 2013) show that the present-day thermal state of Greenland and Antarctic lithosphere cannot be well understood without taking into account a long-term tectonic history of these regions. The goal of the IceGeoHeat project is to combine existing independent geophysical data and innovative modeling approaches to comprehensively study the evolution and present state of the lithosphere in Greenland and Antarctica, and assess the role of geothermal heat flux in shaping the present-day ice sheet dynamics. This requires multiple collaborations involving experts across a range of disciplines. The project builds on the IceGeoHeat initiative formed in April 2012 and now including researchers from ten countries in the main core (MC) with expertise in numerical modeling and data assessment in geodynamics, geology, geothermics, cryosphere and (paleo-)climate. Petrunin, A., Rogozhina, I., Vaughan, A. P. M., Kukkonen, I. T., Kaban, M., Koulakov, I., Thomas, M. (2013): Heat flux variations beneath central Greenland's ice due to anomalously thin lithosphere. - Nature Geoscience, 6, 746-750.

Bovine κ-casein inhibits human rotavirus (HRV) infection via direct binding of glycans to HRV.

PubMed

Inagaki, M; Muranishi, H; Yamada, K; Kakehi, K; Uchida, K; Suzuki, T; Yabe, T; Nakagomi, T; Nakagomi, O; Kanamaru, Y

2014-05-01

Human rotavirus (HRV) is a major etiologic agent of severe infantile gastroenteritis. κ-Casein (κ-CN) from both human and bovine mature milk has been reported to have anti-HRV activity; however, the mechanism of this activity is poorly understood. The present study examined the molecular basis for the protective effect of bovine κ-CN derived from late colostrum (6-7 d after parturition) and from mature milk. Among the components of casein, κ-CN is the only glycosylated protein that has been identified. Therefore, we investigated whether the glycan residues in κ-CN were involved in the anti-HRV activity. Desialylated CN obtained by neuraminidase treatment exhibited anti-HRV activity, whereas deglycosylated CN obtained by o-glycosidase treatment lacked antiviral activity, indicating that glycans were responsible for the antiviral activity of CN. Furthermore, an evanescent-field fluorescence-assisted assay showed that HRV particles directly bound to heated casein (at 95°C for 30 min) in a viral titer-dependent manner. Although the heated κ-CN retained inhibitory activity in a neutralization assay, the activity was weaker than that observed before heat treatment. Our findings indicate that the inhibitory mechanism of bovine κ-CN against HRV involves direct binding to viral particles via glycan residues. In addition, heat-labile structures in κ-CN may play an important role in maintenance of κ-CN binding to HRV. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

EVA space suit Evaporative Cooling/Heating Glove System (ECHGS)

NASA Technical Reports Server (NTRS)

Coss, F. A.

1976-01-01

A new astronaut glove, the Evaporative Cooling/Heating Glove System (ECHGS), was designed and developed to allow the handling of objects between -200 F and +200 F. Active heating elements, positioned at each finger pad, provide additional heat to the finger pads from the rest of the finger. A water evaporative cooling system provides cooling by the injection of water to the finger areas and the subsequent direct evaporation to space. Thin, flexible insulation has been developed for the finger areas to limit thermal conductivity. Component and full glove tests have shown that the glove meets and exceeds the requirements to hold a 11/2 inch diameter bar at + or - 200 F for three minutes within comfort limits. The ECHGS is flexible, lightweight and comfortable. Tactility is reasonable and small objects can be identified especially by the fingertips beyond the one half width active elements.

High-order corrections on the laser cooling limit in the Lamb-Dicke regime.

PubMed

Yi, Zhen; Gu, Wen-Ju

2017-01-23

We investigate corrections on the cooling limit of high-order Lamb-Dicke (LD) parameters in the double electromagnetically induced transparency (EIT) cooling scheme. Via utilizing quantum interferences, the single-phonon heating mechanism vanishes and the system evolves to a double dark state, from which we will obtain the mechanical occupation on the single-phonon excitation state. In addition, the further correction induced by two-phonon heating transitions is included to achieve a more accurate cooling limit. There exist two pathways of two-phonon heating transitions: direct two-phonon excitation from the dark state and further excitation from the single-phonon excited state. By adding up these two parts of correction, the obtained analytical predictions show a well consistence with numerical results. Moreover, we find that the two pathways can destructively interfere with each other, leading to the elimination of two-phonon heating transitions and achieving a lower cooling limit.

Plasma vitrification and re-use of non-combustible fiber reinforced plastic, gill net and waste glass.

PubMed

Chu, J P; Chen, Y T; Mahalingam, T; Tzeng, C C; Cheng, T W

2006-12-01

Fiber reinforced plastic (FRP) composite material has widespread use in general tank, special chemical tank and body of yacht, etc. The purpose of this study is directed towards the volume reduction of non-combustible FRP by thermal plasma and recycling of vitrified slag with specific procedures. In this study, we have employed three main wastes such as, FRP, gill net and waste glass. The thermal molten process was applied to treat vitrified slag at high temperatures whereas in the post-heat treatment vitrified slags were mixed with specific additive and ground into powder form and then heat treated at high temperatures. With a two-stage heat treatment, the treated sample was generated into four crystalline phases, cristobalite, albite, anorthite and wollastonite. Fine and relatively high dense structures with desirable properties were obtained for samples treated by the two-stage heating treatment. Good physical and mechanical properties were achieved after heat treatment, and this study reveals that our results could be comparable with the commercial products.

Liquid belt radiator design study

NASA Technical Reports Server (NTRS)

Teagan, W. P.; Fitzgerald, K. F.

1986-01-01

The Liquid Belt Radiator (LBR) is an advanced concept developed to meet the needs of anticipated future space missions. A previous study documented the advantages of this concept as a lightweight, easily deployable alternative to present day space heat rejection systems. The technical efforts associated with this study concentrate on refining the concept of the LBR as well as examining the issues of belt dynamics and potential application of the LBR to intermediate and high temperature heat rejection applications. A low temperature point design developed in previous work is updated assuming the use of diffusion pump oil, Santovac-6, as the heat transfer media. Additional analytical and design effort is directed toward determining the impact of interface heat exchanger, fluid bath sealing, and belt drive mechanism designs on system performance and mass. The updated design supports the earlier result by indicating a significant reduction in system specific system mass as compared to heat pipe or pumped fluid radiator concepts currently under consideration (1.3 kg/sq m versus 5 kg/sq m).

Electron and ion heating by whistler turbulence: Three-dimensional particle-in-cell simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hughes, R. Scott; Gary, S. Peter; Wang, Joseph

2014-12-17

Three-dimensional particle-in-cell simulations of decaying whistler turbulence are carried out on a collisionless, homogeneous, magnetized, electron-ion plasma model. In addition, the simulations use an initial ensemble of relatively long wavelength whistler modes with a broad range of initial propagation directions with an initial electron beta β e = 0.05. The computations follow the temporal evolution of the fluctuations as they cascade into broadband turbulent spectra at shorter wavelengths. Three simulations correspond to successively larger simulation boxes and successively longer wavelengths of the initial fluctuations. The computations confirm previous results showing electron heating is preferentially parallel to the background magnetic fieldmore » B o, and ion heating is preferentially perpendicular to B o. The new results here are that larger simulation boxes and longer initial whistler wavelengths yield weaker overall dissipation, consistent with linear dispersion theory predictions of decreased damping, stronger ion heating, consistent with a stronger ion Landau resonance, and weaker electron heating.« less

Drying Milk With Boiler Exhaust

NASA Technical Reports Server (NTRS)

Broussard, M. R.

1984-01-01

Considerable energy saved in powdered-milk industry. Only special requirement boiler fired with natural gas or other clean fuel. Boiler flue gas fed to spray drier where it directly contacts product to be dried. Additional heat supplied by auxillary combustor when boiler output is low. Approach adaptable to existing plants with minimal investment because most already equipped with natural-gas-fired boilers.

ASRDI oxygen technology survey. Volume 3: Heat transfer and fluid dynamics. Abstracts of selected technical reports and publications

NASA Technical Reports Server (NTRS)

Schmidt, A. F. (Editor)

1972-01-01

Selected information is presented from an assemblage of reports and publications on heat transfer and fluid dynamics with direct applicability to oxygen systems. For each document cited, an abstract has been prepared together with key words and a listing of most important references found in the document. Additionally, an author index, a subject index, and a key word index have been provided to simplify the retrieval of specific information from this work. In each subject area - e.g., boiling heat transfer - the individual citations are listed alphabetically by first author, with review papers dually noted under the appropriate subject category and under review papers. Of the documents reviewed and evaluated for inclusion in this publication, coverage of existing information directly concerned with oxygen was given primary emphasis. However, work not specifically oxygen-designated but considered applicable to oxygen by the reviewer e.g., a two-phase friction factor correlation derived from nitrogen experiments is occasionally given where no actual oxygen data exist, as an aid to the reader. Approximately 130 abstracts are listed.

Direct simulations of chemically reacting turbulent mixing layers, part 2

NASA Technical Reports Server (NTRS)

Metcalfe, Ralph W.; Mcmurtry, Patrick A.; Jou, Wen-Huei; Riley, James J.; Givi, Peyman

1988-01-01

The results of direct numerical simulations of chemically reacting turbulent mixing layers are presented. This is an extension of earlier work to a more detailed study of previous three dimensional simulations of cold reacting flows plus the development, validation, and use of codes to simulate chemically reacting shear layers with heat release. Additional analysis of earlier simulations showed good agreement with self similarity theory and laboratory data. Simulations with a two dimensional code including the effects of heat release showed that the rate of chemical product formation, the thickness of the mixing layer, and the amount of mass entrained into the layer all decrease with increasing rates of heat release. Subsequent three dimensional simulations showed similar behavior, in agreement with laboratory observations. Baroclinic torques and thermal expansion in the mixing layer were found to produce changes in the flame vortex structure that act to diffuse the pairing vortices, resulting in a net reduction in vorticity. Previously unexplained anomalies observed in the mean velocity profiles of reacting jets and mixing layers were shown to result from vorticity generation by baroclinic torques.

Characteristics of turbulence transport for momentum and heat in particle-laden turbulent vertical channel flows

NASA Astrophysics Data System (ADS)

Liu, Caixi; Tang, Shuai; Shen, Lian; Dong, Yuhong

2017-10-01

The dynamic and thermal performance of particle-laden turbulent flow is investigated via direction numerical simulation combined with the Lagrangian point-particle tracking under the condition of two-way coupling, with a focus on the contributions of particle feedback effect to momentum and heat transfer of turbulence. We take into account the effects of particles on flow drag and Nusselt number and explore the possibility of drag reduction in conjunction with heat transfer enhancement in particle-laden turbulent flows. The effects of particles on momentum and heat transfer are analyzed, and the possibility of drag reduction in conjunction with heat transfer enhancement for the prototypical case of particle-laden turbulent channel flows is addressed. We present results of turbulence modification and heat transfer in turbulent particle-laden channel flow, which shows the heat transfer reduction when large inertial particles with low specific heat capacity are added to the flow. However, we also found an enhancement of the heat transfer and a small reduction of the flow drag when particles with high specific heat capacity are involved. The present results show that particles, which are active agents, interact not only with the velocity field, but also the temperature field and can cause a dissimilarity in momentum and heat transport. This demonstrates that the possibility to increase heat transfer and suppress friction drag can be achieved with addition of particles with different thermal properties.

Direct fired heat exchanger

DOEpatents

Reimann, Robert C.; Root, Richard A.

1986-01-01

A gas-to-liquid heat exchanger system which transfers heat from a gas, generally the combustion gas of a direct-fired generator of an absorption machine, to a liquid, generally an absorbent solution. The heat exchanger system is in a counterflow fluid arrangement which creates a more efficient heat transfer.

Active heat exchange system development for latent heat thermal energy storage

NASA Technical Reports Server (NTRS)

Alario, J.; Kosson, R.; Haslett, R.

1980-01-01

Various active heat exchange concepts were identified from among three generic categories: scrapers, agitators/vibrators and slurries. The more practical ones were given a more detailed technical evaluation and an economic comparison with a passive tube-shell design for a reference application (300 MW sub t storage for 6 hours). Two concepts were selected for hardware development: (1) a direct contact heat exchanger in which molten salt droplets are injected into a cooler counterflowing stream of liquid metal carrier fluid, and (2) a rotating drum scraper in which molten salt is sprayed onto the circumference of a rotating drum, which contains the fluid salt is sprayed onto the circumference of a rotating drum, which contains the fluid heat sink in an internal annulus near the surface. A fixed scraper blade removes the solidified salt from the surface which was nickel plated to decrease adhesion forces. In addition to improving performance by providing a nearly constant transfer rate during discharge, these active heat exchanger concepts were estimated to cost at least 25% less than the passive tube-shell design.

Direct-Drive Gas-Cooled Reactor Power System: Concept and Preliminary Testing

NASA Technical Reports Server (NTRS)

Wright, S. A.; Lipinski, R. J.; Godfroy, T. J.; Bragg-Sitton, S. M.; VanDyke, M. K.

2002-01-01

This paper describes the concept and preliminary component testing of a gas-cooled, UN-fueled, pin-type reactor which uses He/Xe gas that goes directly into a recuperated Brayton system to produce electricity for nuclear electric propulsion. This Direct-Drive Gas-Cooled Reactor (DDG) is designed to be subcritical under water or wet- sand immersion in case of a launch accident. Because the gas-cooled reactor can directly drive the Brayton turbomachinery, it is possible to configure the system such that there are no external surfaces or pressure boundaries that are refractory metal, even though the gas delivered to the turbine is 1144 K. The He/Xe gas mixture is a good heat transport medium when flowing, and a good insulator when stagnant. Judicious use of stagnant cavities as insulating regions allows transport of the 1144-K gas while keeping all external surfaces below 900 K. At this temperature super-alloys (Hastelloy or Inconel) can be used instead of refractory metals. Super-alloys reduce the technology risk because they are easier to fabricate than refractory metals, we have a much more extensive knowledge base on their characteristics, and, because they have a greater resistance to oxidation, system testing is eased. The system is also relatively simple in its design: no additional coolant pumps, heat exchanger, or freeze-thaw systems are required. Key to success of this concept is a good knowledge of the heat transfer between the fuel pins and the gas, as well as the pressure drop through the system. This paper describes preliminary testing to obtain this key information, as well as experience in demonstrating electrically heated testing of simulated reactor components.

Rapid column heating method for subcritical water chromatography.

PubMed

Fogwill, Michael O; Thurbide, Kevin B

2007-01-19

A novel resistive heating method is presented for subcritical water chromatography (SWC) that provides higher column heating rates than those conventionally obtained from temperature-programmed gas chromatography (GC) convection ovens. Since the polarity of water reduces dramatically with increasing temperature, SWC employs column heating to achieve gradient elution. As such, the rate at which the mobile phase is heated directly impacts the magnitude of such gradients applied in SWC. Data from the current study demonstrate that the maximum column heating rate attainable in a typical SWC apparatus (i.e. using a GC convection oven) is around 10 degrees C/min, even at instrument oven settings of over three times this value. Conversely, by wrapping the separation column with ceramic insulation and a resistively heated wire, the column heating rates are increased five-fold. As a result, elution times can be greatly decreased in SWC employing gradients. Separations of standard alcohol test mixtures demonstrate that the retention time of the latest eluting component decreases by 35 to 50% using the prototype method. Additionally, solute retention times in this mode deviate by less than 1% RSD over several trials, which compares very well to those obtained using a conventional GC convection oven. Results suggest that the developed method can be a useful alternative heating technique in SWC.

Anomalous Ion Heating, Intrinsic and Induced Rotation in the Pegasus Toroidal Experiment

NASA Astrophysics Data System (ADS)

Burke, M. G.; Barr, J. L.; Bongard, M. W.; Fonck, R. J.; Hinson, E. T.; Perry, J. M.; Redd, A. J.; Thome, K. E.

2014-10-01

Pegasus plasmas are initiated through either standard, MHD stable, inductive current drive or non-solenoidal local helicity injection (LHI) current drive with strong reconnection activity, providing a rich environment to study ion dynamics. During LHI discharges, a large amount of anomalous impurity ion heating has been observed, with Ti ~ 800 eV but Te < 100 eV. The ion heating is hypothesized to be a result of large-scale magnetic reconnection activity, as the amount of heating scales with increasing fluctuation amplitude of the dominant, edge localized, n = 1 MHD mode. Chordal Ti spatial profiles indicate centrally peaked temperatures, suggesting a region of good confinement near the plasma core surrounded by a stochastic region. LHI plasmas are observed to rotate, perhaps due to an inward radial current generated by the stochastization of the plasma edge by the injected current streams. H-mode plasmas are initiated using a combination of high-field side fueling and Ohmic current drive. This regime shows a significant increase in rotation shear compared to L-mode plasmas. In addition, these plasmas have been observed to rotate in the counter-Ip direction without any external momentum sources. The intrinsic rotation direction is consistent with predictions from the saturated Ohmic confinement regime. Work supported by US DOE Grant DE-FG02-96ER54375.

Condensing Heat Exchanger Concept Developed for Space Systems

NASA Technical Reports Server (NTRS)

Hasan, Mohammad M.; Nayagam, Vedha

2005-01-01

The current system for moisture removal and humidity control for the space shuttles and the International Space Station uses a two-stage process. Water first condenses onto fins and is pulled through "slurper bars." These bars take in a two-phase mixture of air and water that is then separated by the rotary separator. A more efficient design would remove the water directly from the air without the need of an additional water separator downstream. For the Condensing Heat Exchanger for Space Systems (CHESS) project, researchers at the NASA Glenn Research Center in collaboration with NASA Johnson Space Center are designing a condensing heat exchanger that utilizes capillary forces to collect and remove water and that can operate in varying gravitational conditions including microgravity, lunar gravity, and Martian gravity.

Efficient graphite ring heater suitable for diamond-anvil cells to 1300 K

DOE Office of Scientific and Technical Information (OSTI.GOV)

Du Zhixue; Amulele, George; Lee, Kanani K. M.

In order to generate homogeneous high temperatures at high pressures, a ring-shaped graphite heater has been developed to resistively heat diamond-anvil cell (DAC) samples up to 1300 K. By putting the heater in direct contact with the diamond anvils, this graphite heater design features the following advantages: (1) efficient heating: sample can be heated to 1300 K while the DAC body temperature remains less than 800 K, eliminating the requirement of a special alloy for the DAC; (2) compact design: the sample can be analyzed with in situ measurements, e.g., x-ray, optical, and electrical probes are possible. In particular, themore » side access of the heater allows for radial x-ray diffraction (XRD) measurements in addition to traditional axial XRD.« less

First-principles simulations of heat transport

NASA Astrophysics Data System (ADS)

Puligheddu, Marcello; Gygi, Francois; Galli, Giulia

2017-11-01

Advances in understanding heat transport in solids were recently reported by both experiment and theory. However an efficient and predictive quantum simulation framework to investigate thermal properties of solids, with the same complexity as classical simulations, has not yet been developed. Here we present a method to compute the thermal conductivity of solids by performing ab initio molecular dynamics at close to equilibrium conditions, which only requires calculations of first-principles trajectories and atomic forces, thus avoiding direct computation of heat currents and energy densities. In addition the method requires much shorter sequential simulation times than ordinary molecular dynamics techniques, making it applicable within density functional theory. We discuss results for a representative oxide, MgO, at different temperatures and for ordered and nanostructured morphologies, showing the performance of the method in different conditions.

How do Greenhouse Gases Warm the Ocean? Investigation of the Response of the Ocean Thermal Skin Layer to Air-Sea Surface Heat Fluxes.

NASA Astrophysics Data System (ADS)

Wong, E.; Minnett, P. J.

2016-12-01

There is much evidence that the ocean is heating due to an increase in concentrations of greenhouse gases (GHG) in the atmosphere from human activities. GHGs absorbs infrared (IR) radiation and re-emits the radiation back to the ocean's surface which is subsequently absorbed resulting in a rise in the ocean heat content. However, the incoming longwave radiation, LWin, is absorbed within the top micrometers of the ocean's surface, where the thermal skin layer (TSL) exists and does not directly heat the upper few meters of the ocean. We are therefore motivated to investigate the physical mechanism between the absorption of IR radiation and its effect on heat transfer at the air-sea boundary. The hypothesis is that since heat lost through the air-sea interface is controlled by the TSL, which is directly influenced by the absorption and emission of IR radiation, the heat flow through the TSL adjusts to maintain the surface heat loss, and thus modulates the upper ocean heat content. This hypothesis is investigated through utilizing clouds to represent an increase in LWin and analyzing retrieved TSL vertical profiles from a shipboard IR spectrometer from two research cruises. The data is limited to night-time, no precipitation and low winds of < 2 m/s to remove effects of solar radiation, wind-driven shear and possibilities of TSL disruption. The results show independence between the turbulent fluxes and radiative fluxes which rules out the immediate release of heat from the absorption of the cloud infrared irradiance back into the atmosphere through processes such as evaporation. Instead, we observe the surplus energy, from absorbing increasing levels of LWin, adjusts the curvature of the TSL such that there is a lower gradient at the interface between the TSL and the mixed layer. The release of heat stored within the mixed layer is therefore hindered while the additional energy within the TSL is cycled back into the atmosphere. This results in heat beneath the TSL, which is a product of the absorption of solar radiation during the day, to be retained and cause an increase in upper ocean heat content.

Heat recovery system series arrangements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kauffman, Justin P.; Welch, Andrew M.; Dawson, Gregory R.

The present disclosure is directed to heat recovery systems that employ two or more organic Rankine cycle (ORC) units disposed in series. According to certain embodiments, each ORC unit includes an evaporator that heats an organic working fluid, a turbine generator set that expands the working fluid to generate electricity, a condenser that cools the working fluid, and a pump that returns the working fluid to the evaporator. The heating fluid is directed through each evaporator to heat the working fluid circulating within each ORC unit, and the cooling fluid is directed through each condenser to cool the working fluidmore » circulating within each ORC unit. The heating fluid and the cooling fluid flow through the ORC units in series in the same or opposite directions.« less

Analysis of liquid-metal-jet impingement cooling in a corner region and for a row of jets

NASA Technical Reports Server (NTRS)

Siegel, R.

1975-01-01

A conformal mapping method was used to analyze liquid-metal-jet impingement heat transfer. The jet flow region and energy equation are transformed to correspond to uniform flow in a parallel plate channel with nonuniform heat addition along a portion of one wall. The exact solution for the wall-temperature distribution was obtained in the transformed channel, and the results are mapped back into the physical plane. Two geometries are analyzed. One is for a single slot jet directed either into an interior corner formed by two flat plates, or over the external sides of the corner; the flat plates are uniformly heated, and the corner can have various included angles. The heat-transfer coefficient at the stagnation point at the apex of the plates is obtained as a function of the corner angle, and temperature distributions are calculated along the heated walls. The second geometry is an infinite row of uniformly spaced parallel slot jets impinging normally against a uniformly heated plate. The heat-transfer behavior is obtained as a function of the spacing between the jets. Results are given for several jet Peclet numbers from 5 to 50.

75 FR 21777 - Regulatory Agenda

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-26

... flexibility analyses: Energy Efficiency Standards for Pool Heaters and Direct Heating Equipment and Water... Heaters and Direct Heating Equipment and Water 1904-AA90 Heaters 119 Test Procedures for Walk-In Coolers... Renewable Energy (EE) 118. ENERGY EFFICIENCY STANDARDS FOR POOL HEATERS AND DIRECT HEATING EQUIPMENT AND...

Department of Energy Semiannual Regulatory Agenda

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-26

...: Energy Efficiency Standards for Pool Heaters and Direct Heating Equipment and Water Heaters, and Test... EFFICIENCY STANDARDS FOR POOL HEATERS AND DIRECT HEATING EQUIPMENT AND WATER HEATERS Legal Authority: 42 USC... and direct heating equipment. This is the second review for water heaters. Timetable: Action Date FR...

The effect of tantalum on the structure/properties of two polycrystalline nickel-base superalloys: B-1900 + Hf MAR-M247. M.S. Thesis, Final Report

NASA Technical Reports Server (NTRS)

Janowski, G. M.

1985-01-01

The microstructure, phase compositions, and phase fractions were studied in conventionally cast B-1900 + Hf and both conventionally cast and directionally solidified MAR-M247 as a function of tantalum concentration. The hot tensile and creep rupture properties of the solutionized and aged MAR-M247-type alloys were also determined as a function of tantalum level. The effects of tantalum on the microstructure and phase compositions of B-1900 + Hf and MAR-M247 (conventionally cast and directionally solidified) were found to be very similar. The addition of tantalum to the as cast and heat treated alloys was shown to cause the partial replacement of the Hf in the MC carbides by Ta, although the degree of replacement was decreased by the solutionizing and aging heat treatment. The gamma prime and minor phase fractions (primarily MC type carbides) both increased approximately linearly with tantalum concentration. The gamma prime phase compositions were relatively insensitive to tantalum variations with the exception of the tantalum and/or hafnium levels. Bulk tantalum additions increased the tantalum, chromium, and cobalt levels of the gamma phase in both alloy series. The increase in the concentrations of the latter two elements in the gamma phase was a result of the decrease in the gamma phase fraction with increasing bulk tantalum concentration and constant gamma/gamma prime partitioning ratio. Tantalum additions increased the yield stress and ultimate tensile strength of the directionally solidified MAR-M247 type alloys and had no significant effect on ductility.

Additive direct-write microfabrication for MEMS: A review

NASA Astrophysics Data System (ADS)

Teh, Kwok Siong

2017-12-01

Direct-write additive manufacturing refers to a rich and growing repertoire of well-established fabrication techniques that builds solid objects directly from computer- generated solid models without elaborate intermediate fabrication steps. At the macroscale, direct-write techniques such as stereolithography, selective laser sintering, fused deposition modeling ink-jet printing, and laminated object manufacturing have significantly reduced concept-to-product lead time, enabled complex geometries, and importantly, has led to the renaissance in fabrication known as the maker movement. The technological premises of all direct-write additive manufacturing are identical—converting computer generated three-dimensional models into layers of two-dimensional planes or slices, which are then reconstructed sequentially into threedimensional solid objects in a layer-by-layer format. The key differences between the various additive manufacturing techniques are the means of creating the finished layers and the ancillary processes that accompany them. While still at its infancy, direct-write additive manufacturing techniques at the microscale have the potential to significantly lower the barrier-of-entry—in terms of cost, time and training—for the prototyping and fabrication of MEMS parts that have larger dimensions, high aspect ratios, and complex shapes. In recent years, significant advancements in materials chemistry, laser technology, heat and fluid modeling, and control systems have enabled additive manufacturing to achieve higher resolutions at the micrometer and nanometer length scales to be a viable technology for MEMS fabrication. Compared to traditional MEMS processes that rely heavily on expensive equipment and time-consuming steps, direct-write additive manufacturing techniques allow for rapid design-to-prototype realization by limiting or circumventing the need for cleanrooms, photolithography and extensive training. With current direct-write additive manufacturing technologies, it is possible to fabricate unsophisticated micrometer scale structures at adequate resolutions and precisions using materials that range from polymers, metals, ceramics, to composites. In both academia and industry, direct-write additive manufacturing offers extraordinary promises to revolutionize research and development in microfabrication and MEMS technologies. Importantly, direct-write additive manufacturing could appreciably augment current MEMS fabrication technologies, enable faster design-to-product cycle, empower new paradigms in MEMS designs, and critically, encourage wider participation in MEMS research at institutions or for individuals with limited or no access to cleanroom facilities. This article aims to provide a limited review of the current landscape of direct-write additive manufacturing techniques that are potentially applicable for MEMS microfabrication.

Synergistic effects of water addition and step heating on the formation of solution-processed zinc tin oxide thin films: towards high-mobility polycrystalline transistors

NASA Astrophysics Data System (ADS)

Huang, Genmao; Duan, Lian; Zhao, Yunlong; Zhang, Yunge; Dong, Guifang; Zhang, Deqiang; Qiu, Yong

2016-11-01

Thin-film transistors (TFTs) with high mobility and good uniformity are attractive for next-generation flat panel displays. In this work, solution-processed polycrystalline zinc tin oxide (ZTO) thin film with well-ordered microstructure is prepared, thanks to the synergistic effect of water addition and step heating. The step heating treatment other than direct annealing induces crystallization, while adequate water added to precursor solution further facilitates alloying and densification process. The optimal polycrystalline ZTO film is free of hierarchical sublayers, and featured with an increased amount of ternary phases, as well as a decreased fraction of oxygen vacancies and hydroxides. TFT devices based on such an active layer exhibit a remarkable field-effect mobility of 52.5 cm2 V-1 s-1, a current on/off ratio of 2 × 105, a threshold voltage of 2.32 V, and a subthreshold swing of 0.36 V dec-1. Our work offers a facile method towards high-performance solution-processed polycrystalline metal oxide TFTs.

Parallel transmit excitation at 1.5 T based on the minimization of a driving function for device heating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gudino, N., E-mail: natalia.gudino@nih.gov; Sonmez, M.; Nielles-Vallespin, S.

2015-01-15

Purpose: To provide a rapid method to reduce the radiofrequency (RF) E-field coupling and consequent heating in long conductors in an interventional MRI (iMRI) setup. Methods: A driving function for device heating (W) was defined as the integration of the E-field along the direction of the wire and calculated through a quasistatic approximation. Based on this function, the phases of four independently controlled transmit channels were dynamically changed in a 1.5 T MRI scanner. During the different excitation configurations, the RF induced heating in a nitinol wire immersed in a saline phantom was measured by fiber-optic temperature sensing. Additionally, amore » minimization of W as a function of phase and amplitude values of the different channels and constrained by the homogeneity of the RF excitation field (B{sub 1}) over a region of interest was proposed and its results tested on the benchtop. To analyze the validity of the proposed method, using a model of the array and phantom setup tested in the scanner, RF fields and SAR maps were calculated through finite-difference time-domain (FDTD) simulations. In addition to phantom experiments, RF induced heating of an active guidewire inserted in a swine was also evaluated. Results: In the phantom experiment, heating at the tip of the device was reduced by 92% when replacing the body coil by an optimized parallel transmit excitation with same nominal flip angle. In the benchtop, up to 90% heating reduction was measured when implementing the constrained minimization algorithm with the additional degree of freedom given by independent amplitude control. The computation of the optimum phase and amplitude values was executed in just 12 s using a standard CPU. The results of the FDTD simulations showed similar trend of the local SAR at the tip of the wire and measured temperature as well as to a quadratic function of W, confirming the validity of the quasistatic approach for the presented problem at 64 MHz. Imaging and heating reduction of the guidewire were successfully performed in vivo with the proposed hardware and phase control. Conclusions: Phantom and in vivo data demonstrated that additional degrees of freedom in a parallel transmission system can be used to control RF induced heating in long conductors. A novel constrained optimization approach to reduce device heating was also presented that can be run in just few seconds and therefore could be added to an iMRI protocol to improve RF safety.« less

Fiber Orientation Effects in Fused Filament Fabrication of Air-Cooled Heat Exchangers

NASA Astrophysics Data System (ADS)

Mulholland, T.; Goris, S.; Boxleitner, J.; Osswald, T. A.; Rudolph, N.

2018-03-01

Fused filament fabrication (FFF) is a type of additive manufacturing based on material extrusion that has long been considered a prototyping technology. However, the right application of material, process, and product can be used for manufacturing of end-use products, such as air-cooled heat exchangers made by adding fillers to the base polymer, enhancing the thermal conductivity. Fiber fillers lead to anisotropic thermal conductivity, which is governed by the process-induced fiber orientation. This article presents an experimental study on the microstructure-property relationship for carbon fiber-filled polyamide used in FFF. The fiber orientation is measured by micro-computed tomography, and the thermal conductivity of manufactured samples is measured. Although the thermal conductivity is raised by more than three times in the fiber orientation direction at a load of only 12 vol.%, the enhancement is low in the other directions, and this anisotropy, along with certain manufacturing restrictions, influences the final part performance.

Heating and cooling of the neutral ISM in the NGC 4736 circumnuclear ring

NASA Astrophysics Data System (ADS)

van der Laan, T. P. R.; Armus, L.; Beirao, P.; Sandstrom, K.; Groves, B.; Schinnerer, E.; Draine, B. T.; Smith, J. D.; Galametz, M.; Wolfire, M.; Croxall, K.; Dale, D.; Herrera Camus, R.; Calzetti, D.; Kennicutt, R. C.

2015-03-01

The manner in which gas accretes and orbits within circumnuclear rings has direct implications for the star formation process. In particular, gas may be compressed and shocked at the inflow points, resulting in bursts of star formation at these locations. Afterwards the gas and young stars move together through the ring. In addition, star formation may occur throughout the ring, if and when the gas reaches sufficient density to collapse under gravity. These two scenarios for star formation in rings are often referred to as the "pearls-on-a-string" and "popcorn" paradigms. In this paper, we use new Herschel/PACS observations, obtained as part of the KINGFISH open time key program, along with archival Spitzer and ground-based observations from the SINGS Legacy project, to investigate the heating and cooling of the interstellar medium in the nearby star-forming ring galaxy, NGC 4736. By comparing spatially resolved estimates of the stellar far-ultraviolet flux available for heating, with the gas and dust cooling derived from the far-infrared continuum and line emission, we show that while star formation is indeed dominant at the inflow points in NGC 4736, additional star formation is needed to balance the gas heating and cooling throughout the ring. This additional component most likely arises from the general increase in gas density in the ring over its lifetime. Our data provide strong evidence, therefore, for a combination of the two paradigms for star formation in the ring in NGC 4736.

An assessment of thermodynamic merits for current and potential future engine operating strategies

DOE PAGES

Wissink, Martin L.; Splitter, Derek A.; Dempsey, Adam B.; ...

2017-02-01

The present work compares the fundamental thermodynamic underpinnings (i.e., working fluid properties and heat release profile) of various combustion strategies with engine measurements. The approach employs a model that separately tracks the impacts on efficiency due to differences in rate of heat addition, volume change, mass addition, and molecular weight change for a given combination of working fluid, heat release profile, and engine geometry. Comparative analysis between measured and modeled efficiencies illustrates fundamental sources of efficiency reductions or opportunities inherent to various combustion regimes. Engine operating regimes chosen for analysis include stoichiometric spark-ignited combustion and lean compression-ignited combustion including HCCI,more » SA-HCCI, RCCI, GCI, and CDC. Within each combustion regime, effects such as engine load, combustion duration, combustion phasing, combustion chamber geometry, fuel properties, and charge dilution are explored. Model findings illustrate that even in the absence of losses such as heat transfer or incomplete combustion, the maximum possible thermal efficiency inherent to each operating strategy varies to a significant degree. Additionally, the experimentally measured losses are observed to be unique within a given operating strategy. The findings highlight the fact that in order to create a roadmap for future directions in ICE technologies, it is important to not only compare the absolute real-world efficiency of a given combustion strategy, but to also examine the measured efficiency in context of what is thermodynamically possible with the working fluid and boundary conditions prescribed by a strategy.« less

An assessment of thermodynamic merits for current and potential future engine operating strategies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wissink, Martin L.; Splitter, Derek A.; Dempsey, Adam B.

The present work compares the fundamental thermodynamic underpinnings (i.e., working fluid properties and heat release profile) of various combustion strategies with engine measurements. The approach employs a model that separately tracks the impacts on efficiency due to differences in rate of heat addition, volume change, mass addition, and molecular weight change for a given combination of working fluid, heat release profile, and engine geometry. Comparative analysis between measured and modeled efficiencies illustrates fundamental sources of efficiency reductions or opportunities inherent to various combustion regimes. Engine operating regimes chosen for analysis include stoichiometric spark-ignited combustion and lean compression-ignited combustion including HCCI,more » SA-HCCI, RCCI, GCI, and CDC. Within each combustion regime, effects such as engine load, combustion duration, combustion phasing, combustion chamber geometry, fuel properties, and charge dilution are explored. Model findings illustrate that even in the absence of losses such as heat transfer or incomplete combustion, the maximum possible thermal efficiency inherent to each operating strategy varies to a significant degree. Additionally, the experimentally measured losses are observed to be unique within a given operating strategy. The findings highlight the fact that in order to create a roadmap for future directions in ICE technologies, it is important to not only compare the absolute real-world efficiency of a given combustion strategy, but to also examine the measured efficiency in context of what is thermodynamically possible with the working fluid and boundary conditions prescribed by a strategy.« less

Overview of Heat Addition and Efficiency Predictions for an Advanced Stirling Convertor

NASA Technical Reports Server (NTRS)

Wilson, Scott D.; Reid, Terry V.; Schifer, Nicholas A.; Briggs, Maxwell H.

2012-01-01

The U.S. Department of Energy (DOE) and Lockheed Martin Space Systems Company (LMSSC) have been developing the Advanced Stirling Radioisotope Generator (ASRG) for use as a power system for space science missions. This generator would use two high-efficiency Advanced Stirling Convertors (ASCs), developed by Sunpower Inc. and NASA Glenn Research Center (GRC). The ASCs convert thermal energy from a radioisotope heat source into electricity. As part of ground testing of these ASCs, different operating conditions are used to simulate expected mission conditions. These conditions require achieving a particular operating frequency, hot end and cold end temperatures, and specified electrical power output for a given net heat input. Microporous bulk insulation is used in the ground support test hardware to minimize the loss of thermal energy from the electric heat source to the environment. The insulation package is characterized before operation to predict how much heat will be absorbed by the convertor and how much will be lost to the environment during operation. In an effort to validate these predictions, numerous tasks have been performed, which provided a more accurate value for net heat input into the ASCs. This test and modeling effort included: (a) making thermophysical property measurements of test setup materials to provide inputs to the numerical models, (b) acquiring additional test data that was collected during convertor tests to provide numerical models with temperature profiles of the test setup via thermocouple and infrared measurements, (c) using multidimensional numerical models (computational fluid dynamics code) to predict net heat input of an operating convertor, and (d) using validation test hardware to provide direct comparison of numerical results and validate the multidimensional numerical models used to predict convertor net heat input. This effort produced high fidelity ASC net heat input predictions, which were successfully validated using specially designed test hardware enabling measurement of heat transferred through a simulated Stirling cycle. The overall effort and results are discussed.

76 FR 63211 - Energy Efficiency Program: Test Procedures for Residential Water Heaters, Direct Heating...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-12

..., sections 1.7 and 1.12. The definition for ``Storage-type Water Heater of More than 2 Gallons (7.6 Liters) and Less than 20 Gallons (76 Liters)'' is currently reserved. Id. at section 1.12.5. DOE is... another. In addition, these studies suggest that the existing draw pattern in the simulated use test may...

Occupational heat stress assessment and protective strategies in the context of climate change

NASA Astrophysics Data System (ADS)

Gao, Chuansi; Kuklane, Kalev; Östergren, Per-Olof; Kjellstrom, Tord

2018-03-01

Global warming will unquestionably increase the impact of heat on individuals who work in already hot workplaces in hot climate areas. The increasing prevalence of this environmental health risk requires the improvement of assessment methods linked to meteorological data. Such new methods will help to reveal the size of the problem and design appropriate interventions at individual, workplace and societal level. The evaluation of occupational heat stress requires measurement of four thermal climate factors (air temperature, humidity, air velocity and heat radiation); available weather station data may serve this purpose. However, the use of meteorological data for occupational heat stress assessment is limited because weather stations do not traditionally and directly measure some important climate factors, e.g. solar radiation. In addition, local workplace environmental conditions such as local heat sources, metabolic heat production within the human body, and clothing properties, all affect the exchange of heat between the body and the environment. A robust occupational heat stress index should properly address all these factors. This article reviews and highlights a number of selected heat stress indices, indicating their advantages and disadvantages in relation to meteorological data, local workplace environments, body heat production and the use of protective clothing. These heat stress and heat strain indices include Wet Bulb Globe Temperature, Discomfort Index, Predicted Heat Strain index, and Universal Thermal Climate Index. In some cases, individuals may be monitored for heat strain through physiological measurements and medical supervision prior to and during exposure. Relevant protective and preventive strategies for alleviating heat strain are also reviewed and proposed.

Occupational heat stress assessment and protective strategies in the context of climate change.

PubMed

Gao, Chuansi; Kuklane, Kalev; Östergren, Per-Olof; Kjellstrom, Tord

2018-03-01

Global warming will unquestionably increase the impact of heat on individuals who work in already hot workplaces in hot climate areas. The increasing prevalence of this environmental health risk requires the improvement of assessment methods linked to meteorological data. Such new methods will help to reveal the size of the problem and design appropriate interventions at individual, workplace and societal level. The evaluation of occupational heat stress requires measurement of four thermal climate factors (air temperature, humidity, air velocity and heat radiation); available weather station data may serve this purpose. However, the use of meteorological data for occupational heat stress assessment is limited because weather stations do not traditionally and directly measure some important climate factors, e.g. solar radiation. In addition, local workplace environmental conditions such as local heat sources, metabolic heat production within the human body, and clothing properties, all affect the exchange of heat between the body and the environment. A robust occupational heat stress index should properly address all these factors. This article reviews and highlights a number of selected heat stress indices, indicating their advantages and disadvantages in relation to meteorological data, local workplace environments, body heat production and the use of protective clothing. These heat stress and heat strain indices include Wet Bulb Globe Temperature, Discomfort Index, Predicted Heat Strain index, and Universal Thermal Climate Index. In some cases, individuals may be monitored for heat strain through physiological measurements and medical supervision prior to and during exposure. Relevant protective and preventive strategies for alleviating heat strain are also reviewed and proposed.

Separating Test Artifacts from Material Behavior in the Oxidation Studies of HfB2 SiC at 2000 deg C and Above (POSTPRINT)

DTIC Science & Technology

2012-02-01

h. Typical weight loss of the SiC grinding media after milling was 0.2 mg (0.2 wt% of the total batch). The powders were sieved through an 80-mesh...crucible (Advalue, Tuscon, AZ; 10 mL Ca -stabilized ZrO2 crucible; 95% ZrO2 and 4 ± 1% Ca ). Direct electrical resistance heat- ing was controlled by the...in furnace heating has been described previously by the authors, which was shown to contain Al and Ca as major impu- rities.15 In addition, HfSiO4

Separating Test Artifacts from Material Behavior in the Oxidation Studies of HfB2-SiC at 2000 degs C and Above (Preprint)

DTIC Science & Technology

2011-11-01

milled for 12 h. Typical weight loss of the SiC grinding media after milling was 0.2 mg (0.2 wt% of the total batch). The powders were sieved...10-mL Ca -stabilized ZrO2 crucible; 95% ZrO2 and 4±1% Ca ). Direct electrical resistance heating was controlled by the power output of an AC power...furnace heating has been described previously by the authors, which was shown to contain Al and Ca as major impurities [14]. Additionally, HfSiO4 (with

Porcine cadaver iris model for iris heating during corneal surgery with a femtosecond laser

NASA Astrophysics Data System (ADS)

Sun, Hui; Fan, Zhongwei; Wang, Jiang; Yan, Ying; Juhasz, Tibor; Kurtz, Ron

2015-03-01

Multiple femtosecond lasers have now been cleared for use for ophthalmic surgery, including for creation of corneal flaps in LASIK surgery. Preliminary study indicated that during typical surgical use, laser energy may pass beyond the cornea with potential effects on the iris. As a model for laser exposure of the iris during femtosecond corneal surgery, we simulated the temperature rise in porcine cadaver iris during direct illumination by the femtosecond laser. Additionally, ex-vivo iris heating due to femtosecond laser irradiation was measured with an infrared thermal camera (Fluke corp. Everett, WA) as a validation of the simulation.

2D modeling of direct laser metal deposition process using a finite particle method

NASA Astrophysics Data System (ADS)

Anedaf, T.; Abbès, B.; Abbès, F.; Li, Y. M.

2018-05-01

Direct laser metal deposition is one of the material additive manufacturing processes used to produce complex metallic parts. A thorough understanding of the underlying physical phenomena is required to obtain a high-quality parts. In this work, a mathematical model is presented to simulate the coaxial laser direct deposition process tacking into account of mass addition, heat transfer, and fluid flow with free surface and melting. The fluid flow in the melt pool together with mass and energy balances are solved using the Computational Fluid Dynamics (CFD) software NOGRID-points, based on the meshless Finite Pointset Method (FPM). The basis of the computations is a point cloud, which represents the continuum fluid domain. Each finite point carries all fluid information (density, velocity, pressure and temperature). The dynamic shape of the molten zone is explicitly described by the point cloud. The proposed model is used to simulate a single layer cladding.

Direct amide formation using radiofrequency heating.

PubMed

Houlding, Thomas K; Tchabanenko, Kirill; Rahman, Md Taifur; Rebrov, Evgeny V

2013-07-07

We present a simple method for direct and solvent-free formation of amides from carboxylic acids and amines using radiofrequency heating. The direct energy coupling of the AC magnetic field via nickel ferrite magnetic nanoparticles enables fast and controllable heating, as well as enabling facile work-up via magnetic separation.

Heat transfer characteristics of a surface type direct contact boiler

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deeds, R.S.; Jacobs, H.R.; Boehm, R.F.

1976-03-01

Two direct contact heat exchangers were constructed and test results were obtained using water and refrigerant 113 as the working fluids. The heat exchangers were operated in a three-phase mode; the water remained liquid throughout the vessel and the liquid refrigerant 113 underwent vaporization following direct injection into the water. The effect of important operational parameters--operating heights, refrigerant 113 injection techniques, mass flow ratios, and temperatures--was studied to determine generalized trends important in the design and operation of a prototype three-phase direct contact heat exchanger. The primary system used in this study performed well overall. The initial favorable results ofmore » this study warrant further investigation of direct contact heat exchange as a means of utilizing geothermal energy.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lv, Q.; Kraus, A.; Hu, R.

CFD analysis has been focused on important component-level phenomena using STARCCM+ to supplement the system analysis of integral system behavior. A notable area of interest was the cavity region. This area is of particular interest for CFD analysis due to the multi-dimensional flow and complex heat transfer (thermal radiation heat transfer and natural convection), which are not simulated directly by RELAP5. CFD simulations allow for the estimation of the boundary heat flux distribution along the riser tubes, which is needed in the RELAP5 simulations. The CFD results can also provide additional data to help establish what level of modeling detailmore » is necessary in RELAP5. It was found that the flow profiles in the cavity region are simpler for the water-based concept than for the air-cooled concept. The local heat flux noticeably increases axially, and is higher in the fins than in the riser tubes. These results were utilized in RELAP5 simulations as boundary conditions, to provide better temperature predictions in the system level analyses. It was also determined that temperatures were higher in the fins than the riser tubes, but within design limits for thermal stresses. Higher temperature predictions were identified in the edge fins, in part due to additional thermal radiation from the side cavity walls.« less

Comfortable, high-efficiency heat pump with desiccant-coated, water-sorbing heat exchangers

PubMed Central

Tu, Y. D.; Wang, R. Z.; Ge, T. S.; Zheng, X.

2017-01-01

Comfortable, efficient, and affordable heating, ventilation, and air conditioning systems in buildings are highly desirable due to the demands of energy efficiency and environmental friendliness. Traditional vapor-compression air conditioners exhibit a lower coefficient of performance (COP) (typically 2.8–3.8) owing to the cooling-based dehumidification methods that handle both sensible and latent loads together. Temperature- and humidity-independent control or desiccant systems have been proposed to overcome these challenges; however, the COP of current desiccant systems is quite small and additional heat sources are usually needed. Here, we report on a desiccant-enhanced, direct expansion heat pump based on a water-sorbing heat exchanger with a desiccant coating that exhibits an ultrahigh COP value of more than 7 without sacrificing any comfort or compactness. The pump’s efficiency is doubled compared to that of pumps currently used in conventional room air conditioners, which is a revolutionary HVAC breakthrough. Our proposed water-sorbing heat exchanger can independently handle sensible and latent loads at the same time. The desiccants adsorb moisture almost isothermally and can be regenerated by condensation heat. This new approach opens up the possibility of achieving ultrahigh efficiency for a broad range of temperature- and humidity-control applications. PMID:28079171

High-fidelity Characterization on Anisotropic Thermal Conductivity of Carbon Nanotube Sheets and on their effects of Thermal Enhancement of Nanocomposites.

PubMed

Zhang, Xiao; Tan, Wei; Smail, Fiona; De Volder, Michael; Fleck, Norman; Boies, Adam

2018-06-19

Some assemblies of nanomaterials, like carbon nanotube (CNT) sheet or film, always show outstanding and anisotropic thermal properties. However, there is still a lack of comprehensive thermal conductivity (κ) characterizations on CNT sheets, as well as lack of estimations of their true contributions on thermal enhancement of polymer composites when used as additives. Always, these characterizations were hindered by the low heat capacity, anisotropic thermal properties or low electrical conductivity of assemblies and their nanocomposites. And the transient κ measurement and calculations were also hampered by accurate determination of parameters, like specific heat capacity, density and cross-section, which could be difficult and controversial for nanomaterials, like CNT sheets. Here, to measure anisotropic κ of CNT sheets directly with high fidelity, we modified the conventional steady-state method by measuring under vacuum and by infrared camera, and then comparing temperature profiles on both reference standard material and a CNT sheet sample. The highly anisotropic thermal conductivities of CNT sheets were characterized comprehensively, with κ/ρ in alignment direction as ~95 mW·m^2/(K·kg). Furthermore, by comparing the measured thermal properties of different CNT-epoxy resin composites, the heat conduction pathway created by the CNT hierarchical network was demonstrated to remain intact after the in-situ polymerization and curing process. The reliable and direct κ measurement rituals used here, dedicated to nanomaterials, will be also essential to assist in assemblies' application to heat dissipation and composite thermal enhancement. © 2018 IOP Publishing Ltd.

Direct energy conversion bottoming cycles for solid oxide fuel cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paramonov, D.V.; Carelli, M.D.

1998-07-01

Besides high conversion efficiency, advantages of Solid Oxide Fuel Cell (SOFC) include ability of low pressure operation, absence of moving parts and resulting inherently low maintenance requirements, modularity, long lifetime and unattended operation. A further increase in the conversion efficiency, without compromising the advantages inherent with static devices, can be achieved by employing a direct energy conversion bottoming cycle. The biggest challenges in the integration of direct energy conversion devices with SOFC are: (a) the need to preheat the SOFC feed air while maximizing the bottoming cycle power, and (b) limited temperature of the SOFC exhaust. These restrictions limit themore » choice to the Alkali Metal Thermal to Electric Conversion (AMTEC) and Thermoelectric (TE) technologies while eliminating thermionics and thermophotovoltaics. In addition to the aforementioned advantages, the SOFC-AMTEC and SOFC-TE cycles are attractive for certain applications such as cogeneration and power supplies for remote locations where the use of higher efficiency dynamic bottoming cycles might be undesirable due to maintenance and noise restrictions. A preliminary feasibility assessment of AMTEC and TE bottoming of SOFC power systems has been performed. Five SOFC bottoming cycle concepts were considered. They include: TE bottoming with cogeneration capability, TE bottoming with additional heat recovery, TE bottoming with uncoupled TE converter and air preheater, AMTEC bottoming, and Cascaded AMTEC-TE bottoming. The cascaded AMTEC-TE bottoming cycle increases the overall cycle efficiency by 4.7 percentage points. TE bottoming cycle with additional heat recovery adds 3.8 percentage points, and the other concepts are between 3 and 3.5 percentage points. The results are also compared with results of similar studies reported in literature. The AMTEC-TE cascade has the largest potential, however, development of both AMTEC and TE components would be required. The second best option from the efficiency point of view is the TE bottoming with additional heat recovery which would require development of only the TE component. Despite that fact that AMTEC is generally perceived as more efficient than thermoelectrics, efficiencies of the considered AMTEC and TE bottoming cycles are almost equal. The reason is that the somewhat more efficient AMTEC requires relatively high hot side temperature ({gt}850--900 K) and, at the same time, air has to be preheated to 973 K. (This is equally true for a high efficiency TE converter operating at the highest hot side to cold side temperature difference possible). As a result, only a small fraction ({lt}30 %) of the total heat available is directed to the bottoming cycle where it is converted with relatively high efficiency. When a TE converter operating in a wider hot side temperature range, but at a smaller hot side--cold side temperature difference is employed, its lower efficiency is offset by its larger thermal power and the overall bottoming cycle efficiency changes insignificantly.« less

Acoustically excited heated jets. 2: In search of a better understanding

NASA Technical Reports Server (NTRS)

Lepicovsky, J.; Ahuja, K. K.; Brown, W. H.; Salikuddin, M.; Morris, P. J.

1988-01-01

The second part of a three-part report on the effects of acoustic excitation on jet mixing includes the results of an experimental investigation directed at resolving the question of poor excitability of some of the heated jets. The theoretical predictions discussed in Part 1 are examined to find explanations for the observed discrepancies between the measured and the predicted results. Additional testing was performed by studying the self excitation of the shock containing hot jets and also by exciting the jet by sound radiated through source tubes located externally around the periphery of the jet. The effects of nozzle-exit boundary layer conditions on jet excitability was also investigated. It is concluded that high-speed, heated jet mixing rates and consequently also the jet excitability strongly depends on nozzle exit boundary layer conditions.

Applications of thermal energy storage to waste heat recovery in the food processing industry

NASA Astrophysics Data System (ADS)

Trebilcox, G. J.; Lundberg, W. L.

1981-03-01

The canning segment of the food processing industry is a major energy user within that industry. Most of its energy demand is met by hot water and steam and those fluids, in addition to product cooling water, eventually flow from the processes as warm waste water. To minimize the possibility of product contamination, a large percentage of that waste water is sent directly to factory drains and sewer systems without being recycled and in many cases the thermal energy contained by the waste streams also goes unreclaimed and is lost from further use. Waste heat recovery in canning facilities can be performed economically using systems that employ thermal energy storage (TES). A project was proposed in which a demonstration waste heat recovery system, including a TES feature, would be designed, installed and operated.

Rankine engine solar power generation. I - Performance and economic analysis

NASA Technical Reports Server (NTRS)

Gossler, A. A.; Orrock, J. E.

1981-01-01

Results of a computer simulation of the performance of a solar flat plate collector powered electrical generation system are presented. The simulation was configured to include locations in New Mexico, North Dakota, Tennessee, and Massachusetts, and considered a water-based heat-transfer fluid collector system with storage. The collectors also powered a Rankine-cycle boiler filled with a low temperature working fluid. The generator was considered to be run only when excess solar heat and full storage would otherwise require heat purging through the collectors. All power was directed into the utility grid. The solar powered generator unit addition was found to be dependent on site location and collector area, and reduced the effective solar cost with collector areas greater than 400-670 sq m. The sites were economically ranked, best to worst: New Mexico, North Dakota, Massachusetts, and Tennessee.

Diesel engine catalytic combustor system. [aircraft engines

NASA Technical Reports Server (NTRS)

Ream, L. W. (Inventor)

1984-01-01

A low compression turbocharged diesel engine is provided in which the turbocharger can be operated independently of the engine to power auxiliary equipment. Fuel and air are burned in a catalytic combustor to drive the turbine wheel of turbine section which is initially caused to rotate by starter motor. By opening a flapper value, compressed air from the blower section is directed to catalytic combustor when it is heated and expanded, serving to drive the turbine wheel and also to heat the catalytic element. To start, engine valve is closed, combustion is terminated in catalytic combustor, and the valve is then opened to utilize air from the blower for the air driven motor. When the engine starts, the constituents in its exhaust gas react in the catalytic element and the heat generated provides additional energy for the turbine section.

Skin tightening.

PubMed

Woolery-Lloyd, Heather; Kammer, Jenna N

2011-01-01

Skin tightening describes the treatment of skin laxity via radiofrequency (RF), ultrasound, or light-based devices. Skin laxity on the face is manifested by progressive loss of skin elasticity, loosening of the connective tissue framework, and deepening of skin folds. This results in prominence of submandibular and submental tissues. Genetic factors (chronological aging) and extrinsic factors (ultraviolet radiation) both contribute to skin laxity. There are many RF, ultrasound, and light-based devices directed at treating skin laxity. All of these devices target and heat the dermis to induce collagen contraction. Heating of the dermis causes collagen denaturation and immediate collagen contraction in addition to long-term collagen remodeling. Via RF, light, or ultrasound, these skin tightening devices deliver heat to the dermis to create new collagen and induce skin tightening. This chapter will provide an overview of the various skin tightening devices. Copyright © 2011 S. Karger AG, Basel.

Sodium sulfate crystallisation monitoring using IR thermography

NASA Astrophysics Data System (ADS)

Vazquez, P.; Thomachot-Schneider, C.; Mouhoubi, K.; Bodnar, J.-L.; Avdelidis, N. P.; Charles, D.; Benavente, D.

2018-03-01

In this work, the evaporation of sodium sulfate droplets with different concentrations and at different temperatures were studied using infrared thermography (IRT). IRT allows to detect the evaporation evolution, the crystal growth and for the first time, to observe in vivo the heat release related to sodium sulfate crystallisation. A detailed study revealed that dendritic Thenardite III crystals appeared at the edge of all the crystallised droplets, though they showed a fast increase of temperature related to crystallisation only when a hydrated phase crystallised also from the droplet. The observation of the heat of crystallisation is thus directly related to the supersaturation of the droplet and consequently to temperature. In addition, IRT detection is circumscribed by the location of crystallisation. The heat can be observed and measured only when the crystallisation occurs in the interface solution - air.

Crystalline-gel-molten phase transitions of water in calcium dipicolinate (Ca-DPA)

NASA Astrophysics Data System (ADS)

Tiwari, Subodh; Mishra, Ankit; Sheng, Chunyang; Rajak, Pankaj; Kalia, Rajiv; Nakano, Aiichiro; Vashishta, Priya

The heat resistance of bacterial spores directly correlates to the protoplast dehydration and presence of dipicolinic acid (DPA) and its associated metal salts at the core. Bacteria's structural integrity in moist heat conferred by high concentration of DPA and calcium DPA salts depends on the properties are additional water molecules and temperature. In our reactive MD simulations, we characterize different possible phases and the transport properties of water molecules. We observed solid-gel and gel-liquid phase transitions of the hydrated Ca-DPA system. These simulations reveal monotonically decreasing solid-gel-liquid transition temperatures with increasing cell hydration, reflecting the experimental trend of moist-heat resistance of bacterial spores. We also observed that the calcification of bacterial spores further increases the transition temperatures. This research is supported by DTRA Grant No. HDTRA1-14-1-0074.

Using Heat Pulses for Quantifying 3d Seepage Velocity in Groundwater-Surface Water Interactions, Considering Source Size, Regime, and Dispersion

NASA Astrophysics Data System (ADS)

Zlotnik, V. A.; Tartakovsky, D. M.

2017-12-01

The study is motivated by rapid proliferation of field methods for measurements of seepage velocity using heat tracing and is directed to broadening their potential for studies of groundwater-surface water interactions, and hyporheic zone in particular. In vast majority, existing methods assume vertical or horizontal, uniform, 1D seepage velocity. Often, 1D transport assumed as well, and analytical models of heat transport by Suzuki-Stallman are heavily used to infer seepage velocity. However, both of these assumptions (1D flow and 1D transport) are violated due to the flow geometry, media heterogeneity, and localized heat sources. Attempts to apply more realistic conceptual models still lack full 3D view, and known 2D examples are treated numerically, or by making additional simplifying assumptions about velocity orientation. Heat pulse instruments and sensors already offer an opportunity to collect data sufficient for 3D seepage velocity identification at appropriate scale, but interpretation tools for groundwater-surface water interactions in 3D have not been developed yet. We propose an approach that can substantially improve capabilities of already existing field instruments without additional measurements. Proposed closed-form analytical solutions are simple and well suited for using in inverse modeling. Field applications and ramifications for applications, including data analysis are discussed. The approach simplifies data collection, determines 3D seepage velocity, and facilitates interpretation of relations between heat transport parameters, fluid flow, and media properties. Results are obtained using tensor properties of transport parameters, Green's functions, and rotational coordinate transformations using the Euler angles

Precipitation of Al3(Sc,Zr) Particles in a Direct Chill Cast Al-Zn-Mg-Cu-Sc-Zr Alloy During Conventional Solution Heat Treatment and its Effect on Tensile Properties

DTIC Science & Technology

2007-12-01

recrystallization during hot working and introduce additional strengthening through the formation of fine coherent Al3(Sc,Zr) particles from a super...microstructure was described in detail elsewhere [8]. TEM analysis of the as-cast alloy revealed large eutectic -forming particles, which were enriched...however suggest that this additional strengthening (~10-30 MPa) can be due to incomplete dissolution of the eutectic phases, which were present in the

Solar rejection for an orbiting telescope

NASA Technical Reports Server (NTRS)

Rehnberg, J. D.

1975-01-01

The present work discusses some of the constraints that the optical designer must deal with in optimizing spaceborne sensors that must look at or near the sun. Analytical techniques are described for predicting the effects of stray radiation from sources such as mirror scatter, baffle scatter, diffraction, and ghost images. In addition, the paper describes a sensor design that has been flown on the Apollo Telescope Mount (Skylab) to aid astronauts in locating solar flares. In addition to keeping stray radiation to a minimum, the design had to be nondegradable by the direct solar heat load.

The analysis of the flow with water injection in a centrifugal compressor stage using CFD simulation

NASA Astrophysics Data System (ADS)

Michal, Tomášek; Richard, Matas; Tomáš, Syka

2017-09-01

This text deals with the principle of direct cooling of the pressure gas in a centrifugal compressor based on evaporation of the additional fluid phase in a control domain. A decrease of the gas temperature is reached by taking the heat, which is required for evaporation of the fluid phase. The influence of additional fluid phase on the parameters of the multiphase flow is compared with the ideal gas simulation in the defined domain and with the same boundary conditions.

SERI Solar Energy Storage Program: FY 1984

NASA Astrophysics Data System (ADS)

Luft, W.; Bohn, M.; Copeland, R. J.; Kreith, F.; Nix, R. G.

1985-02-01

The activities of the Solar Energy Research Institute's Solar Energy Research Institute's Solar Energy Storage Program during its sixth year are summarized. During FY 1984 a study was conducted to identify the most promising high-temperature containment concepts considering corrosion resistance, material strength at high temperature, reliability of performance, and cost. Of the two generic types of high-temperature thermal storage concepts, the single-tank system was selected using a two-medium approach to the thermocline maintenance. This concept promises low costs, but further research is required. A conceptual design for a sand-to-air direct-contact heat exchanger was developed using dual-lock hoppers to introduce the sand into the fluidized-bed exchanger, and using cyclones to remove sand particles from the output air stream. Preliminary cost estimates indicate heat exchanger subsystem annual levelized costs of about $4/GJ with compressor costs of an additional $0.75/GJ. An economic analysis comparing sensible and latent heat storage for nitrate and carbonate salts with solely sensible heat storage showed 3%-21% cost savings with combined sensible and latent heat storage.

Time Dependent Predictive Modeling of DIII-D ITER Baseline Scenario using Predictive TRANSP

NASA Astrophysics Data System (ADS)

Grierson, B. A.; Andre, R. G.; Budny, R. V.; Solomon, W. M.; Yuan, X.; Candy, J.; Pinsker, R. I.; Staebler, G. M.; Holland, C.; Rafiq, T.

2015-11-01

ITER baseline scenario discharges on DIII-D are modeled with TGLF and MMM transitioning from combined ECH (3.3MW) +NBI(2.8MW) heating to NBI only (3.0 MW) heating maintaining βN = 2.0 on DIII-D predicting temperature, density and rotation for comparison to experimental measurements. These models capture the reduction of confinement associated with direct electron heating H98y2 = 0.89 vs. 1.0) consistent with stiff electron transport. Reasonable agreement between experimental and modeled temperature profiles is achieved for both heating methods, whereas density and momentum predictions differ significantly. Transport fluxes from TGLF indicate that on DIII-D the electron energy flux has reached a transition from low-k to high-k turbulence with more stiff high-k transport that inhibits an increase in core electron stored energy with additional electron heating. Projections to ITER also indicate high electron stiffness. Supported by US DOE DE-AC02-09CH11466, DE-FC02-04ER54698, DE-FG02-07ER54917, DE-FG02-92-ER54141.

Effects of lava heating on volatile-rich slopes on Io

USGS Publications Warehouse

Dundas, Colin M.

2017-01-01

The upper crust of Io may be very rich in volatile sulfur and SO2. The surface is also highly volcanically active, and slopes may be warmed by radiant heat from the lava. This is particularly the case in paterae, which commonly host volcanic eruptions and long-lived lava lakes. Paterae slopes are highly variable, but some are greater than 70°. I model the heating of a volatile slope for two end-member cases: instantaneous emplacement of a large sheet flow, and persistent heating by a long-lived lava lake. In general, single flows can briefly raise sulfur to the melting temperature, or drive a modest amount of sublimation of SO2. Persistently lava-covered surfaces will drive much more significant geomorphic effects, with potentially significant sublimation and slope retreat. In addition to the direct effects, heating is likely to weaken slope materials and may trigger mass wasting. Thus, if the upper crust of Io is rich in these volatile species, future missions with high-resolution imaging are likely to observe actively retreating slopes around lava lakes and other locations of frequent eruptions.

Thermal buffering of receivers for parabolic dish solar thermal power plants

NASA Technical Reports Server (NTRS)

Manvi, R.; Fujita, T.; Gajanana, B. C.; Marcus, C. J.

1980-01-01

A parabolic dish solar thermal power plant comprises a field of parabolic dish power modules where each module is composed of a two-axis tracking parabolic dish concentrator which reflects sunlight (insolation) into the aperture of a cavity receiver at the focal point of the dish. The heat generated by the solar flux entering the receiver is removed by a heat transfer fluid. In the dish power module, this heat is used to drive a small heat engine/generator assembly which is directly connected to the cavity receiver at the focal point. A computer analysis is performed to assess the thermal buffering characteristics of receivers containing sensible and latent heat thermal energy storage. Parametric variations of the thermal inertia of the integrated receiver-buffer storage systems coupled with different fluid flow rate control strategies are carried out to delineate the effect of buffer storage, the transient response of the receiver-storage systems and corresponding fluid outlet temperature. It is concluded that addition of phase change buffer storage will substantially improve system operational characteristics during periods of rapidly fluctuating insolation due to cloud passage.

[Hygienic evaluation of direct heating of the air delivered to the shaft].

PubMed

Velichkovskiĭ, B T; Malikov, Iu K; Troitskaia, N A; Belen'kaia, M A; Sergeeva, N V; Shirokova, O V; Kashanskiĭ, S V; Slyshkina, T V; Simonova, O V; Zykova, V A

2011-01-01

The paper gives the results of exploring a test pre-heating system for the air (APHS) delivered to the shaft. The system has been first used in the Urals. The supply air is heated by burning natural gas in the air current. The APHS system with a RG air heater (000 "Gas-Engineering") is equipped in addition to the existing heaters to enhance heat supply reliability in northern conditions. The data of the studies show that in all periods of the heating season (interseason, moderate frosts, the coldest month), the concentrations of hazardous substances, such as nitric oxides, nitric dioxide, sulfur dioxide, carbon dioxide, benz(a)pyrene, solid aerosol in the shaft-delivered air, do not exceed those given in the existing regulation provided that the design operating conditions are met. With the maximum gas consumption, the coldest month only was marked by the nitric dioxide content being greater than the standard values, causing the maximum projected natural gas consumption to be lower in the APHS system. The air level of nitric dioxide proved to be a major hygiene indicator while using this air heater.

An Estimate of Shallow, Low-Temperature Geothermal Resources of the United States

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mullane, Michelle; Gleason, Michael; Reber, Tim

Low-temperature geothermal resources in the United States potentially hold an enormous quantity of thermal energy, useful for direct use in residential, commercial and industrial applications such as space and water heating, greenhouse warming, pool heating, aquaculture, and low-temperature manufacturing processes. Several studies published over the past 40 years have provided assessments of the resource potential for multiple types of low-temperature geothermal systems (e.g. hydrothermal convection, hydrothermal conduction, and enhanced geothermal systems) with varying temperature ranges and depths. This paper provides a summary and additional analysis of these assessments of shallow (= 3 km), low-temperature (30-150 degrees C) geothermal resources inmore » the United States, suitable for use in direct-use applications. This analysis considers six types of geothermal systems, spanning both hydrothermal and enhanced geothermal systems (EGS). We outline the primary data sources and quantitative parameters used to describe resources in each of these categories, and present summary statistics of the total resources available. In sum, we find that low-temperature hydrothermal resources and EGS resources contain approximately 8 million and 800 million TWh of heat-in-place, respectively. In future work, these resource potential estimates will be used for modeling of the technical and market potential for direct-use geothermal applications for the U.S. Department of Energy's Geothermal Vision Study.« less

Resonances in the Field-Angle-Resolved Thermal Conductivity of CeCoIn 5

DOE PAGES

Kim, Duk Y.; Lin, Shi -Zeng; Weickert, Franziska; ...

2017-05-12

Here, the thermal conductivity measurement in a rotating magnetic field is a powerful probe of the structure of the superconducting energy gap. We present high-precision measurements of the low-temperature thermal conductivity in the unconventional heavy-fermion superconductor CeCoIn 5, with the heat current J along the nodal [110] direction of its d x2–y2 order parameter and the magnetic field up to 7 T rotating in the ab plane. In contrast to the smooth oscillations found previously for J∥[100], we observe a sharp resonancelike peak in the thermal conductivity when the magnetic field is also in the [110] direction, parallel to themore » heat current. We explain this peak qualitatively via a model of the heat transport in a d-wave superconductor. In addition, we observe two smaller but also very sharp peaks in the thermal conductivity for the field directions at angles Θ≈±33° with respect to J. The origin of the observed resonances at Θ≈±33° at present defies theoretical explanation. The challenge of uncovering their source will dictate exploring theoretically more complex models, which might include, e.g., fine details of the Fermi surface, Andreev bound vortex core states, a secondary superconducting order parameter, and the existence of gaps in spin and charge excitations.« less

An Estimate of Shallow, Low-Temperature Geothermal Resources of the United States: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mullane, Michelle; Gleason, Michael; McCabe, Kevin

Low-temperature geothermal resources in the United States potentially hold an enormous quantity of thermal energy, useful for direct use in residential, commercial and industrial applications such as space and water heating, greenhouse warming, pool heating, aquaculture, and low-temperature manufacturing processes. Several studies published over the past 40 years have provided assessments of the resource potential for multiple types of low-temperature geothermal systems (e.g. hydrothermal convection, hydrothermal conduction, and enhanced geothermal systems) with varying temperature ranges and depths. This paper provides a summary and additional analysis of these assessments of shallow (= 3 km), low-temperature (30-150 degrees C) geothermal resources inmore » the United States, suitable for use in direct-use applications. This analysis considers six types of geothermal systems, spanning both hydrothermal and enhanced geothermal systems (EGS). We outline the primary data sources and quantitative parameters used to describe resources in each of these categories, and present summary statistics of the total resources available. In sum, we find that low-temperature hydrothermal resources and EGS resources contain approximately 8 million and 800 million TWh of heat-in-place, respectively. In future work, these resource potential estimates will be used for modeling of the technical and market potential for direct-use geothermal applications for the U.S. Department of Energy's Geothermal Vision Study.« less

Resonances in the Field-Angle-Resolved Thermal Conductivity of CeCoIn 5

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Duk Y.; Lin, Shi -Zeng; Weickert, Franziska

Here, the thermal conductivity measurement in a rotating magnetic field is a powerful probe of the structure of the superconducting energy gap. We present high-precision measurements of the low-temperature thermal conductivity in the unconventional heavy-fermion superconductor CeCoIn 5, with the heat current J along the nodal [110] direction of its d x2–y2 order parameter and the magnetic field up to 7 T rotating in the ab plane. In contrast to the smooth oscillations found previously for J∥[100], we observe a sharp resonancelike peak in the thermal conductivity when the magnetic field is also in the [110] direction, parallel to themore » heat current. We explain this peak qualitatively via a model of the heat transport in a d-wave superconductor. In addition, we observe two smaller but also very sharp peaks in the thermal conductivity for the field directions at angles Θ≈±33° with respect to J. The origin of the observed resonances at Θ≈±33° at present defies theoretical explanation. The challenge of uncovering their source will dictate exploring theoretically more complex models, which might include, e.g., fine details of the Fermi surface, Andreev bound vortex core states, a secondary superconducting order parameter, and the existence of gaps in spin and charge excitations.« less

A passive cooling system proposal for multifunction and high-power displays

NASA Astrophysics Data System (ADS)

Tari, Ilker

2013-03-01

Flat panel displays are conventionally cooled by internal natural convection, which constrains the possible rate of heat transfer from the panel. On one hand, during the last few years, the power consumption and the related cooling requirement for 1080p displays have decreased mostly due to energy savings by the switch to LED backlighting and more efficient electronics. However, on the other hand, the required cooling rate recently started to increase with new directions in the industry such as 3D displays, and ultra-high-resolution displays (recent 4K announcements and planned introduction of 8K). In addition to these trends in display technology itself, there is also a trend to integrate consumer entertainment products into displays with the ultimate goal of designing a multifunction device replacing the TV, the media player, the PC, the game console and the sound system. Considering the increasing power requirement for higher fidelity in video processing, these multifunction devices tend to generate very high heat fluxes, which are impossible to dissipate with internal natural convection. In order to overcome this obstacle, instead of active cooling with forced convection that comes with drawbacks of noise, additional power consumption, and reduced reliability, a passive cooling system relying on external natural convection and radiation is proposed here. The proposed cooling system consists of a heat spreader flat heat pipe and aluminum plate-finned heat sink with anodized surfaces. For this system, the possible maximum heat dissipation rates from the standard size panels (in 26-70 inch range) are estimated by using our recently obtained heat transfer correlations for the natural convection from aluminum plate-finned heat sinks together with the surface-to-surface radiation. With the use of the proposed passive cooling system, the possibility of dissipating very high heat rates is demonstrated, hinting a promising green alternative to active cooling.

Exploration of high harmonic fast wave heating on the National Spherical Torus Experiment

NASA Astrophysics Data System (ADS)

Wilson, J. R.; Bell, R. E.; Bernabei, S.; Bitter, M.; Bonoli, P.; Gates, D.; Hosea, J.; LeBlanc, B.; Mau, T. K.; Medley, S.; Menard, J.; Mueller, D.; Ono, M.; Phillips, C. K.; Pinsker, R. I.; Raman, R.; Rosenberg, A.; Ryan, P.; Sabbagh, S.; Stutman, D.; Swain, D.; Takase, Y.; Wilgen, J.

2003-05-01

High harmonic fast wave (HHFW) heating has been proposed as a particularly attractive means for plasma heating and current drive in the high beta plasmas that are achievable in spherical torus (ST) devices. The National Spherical Torus Experiment (NSTX) [M. Ono, S. M. Kaye, S. Neumeyer et al., in Proceedings of the 18th IEEE/NPSS Symposium on Fusion Engineering, Albuquerque, 1999 (IEEE, Piscataway, NJ, 1999), p. 53] is such a device. An rf heating system has been installed on the NSTX to explore the physics of HHFW heating, current drive via rf waves and for use as a tool to demonstrate the attractiveness of the ST concept as a fusion device. To date, experiments have demonstrated many of the theoretical predictions for HHFW. In particular, strong wave absorption on electrons over a wide range of plasma parameters and wave parallel phase velocities, wave acceleration of energetic ions, and indications of current drive for directed wave spectra have been observed. In addition HHFW heating has been used to explore the energy transport properties of NSTX plasmas, to create H-mode discharges with a large fraction of bootstrap current and to control the plasma current profile during the early stages of the discharge.

Investigating the interactions of decentralized and centralized wastewater heat recovery systems.

PubMed

Sitzenfrei, Robert; Hillebrand, Sebastian; Rauch, Wolfgang

2017-03-01

In the urban water cycle there are different sources for extracting energy. In addition to potential and chemical energy in the wastewater, thermal energy can also be recovered. Heat can be recovered from the wastewater with heat exchangers that are located decentralized and/or centralized at several locations throughout the system. It can be recovered directly at the source (e.g. in the showers and bathrooms), at building block level (e.g. warm water tanks collecting all grey water), in sewers or at the wastewater treatment plant. However, an uncoordinated installation of systems on such different levels can lead to competing technologies. To investigate these interactions, a modelling environment is set up, tested and calibrated based on continuous sewer temperature and flow measurements. With that approach different heat recovery scenarios on a household level (decentralized) and of in-sewer heat recovery (centralized) are investigated. A maximum performance drop of 40% for a centralized energy recovery system was estimated when all bathrooms are equipped with decentralized recovery systems. Therefore, the proposed modelling approach is suitable for testing different future conditions and to identify robust strategies for heat recovery systems from wastewater.

Methods to Calculate the Heat Index as an Exposure Metric in Environmental Health Research

PubMed Central

Bell, Michelle L.; Peng, Roger D.

2013-01-01

Background: Environmental health research employs a variety of metrics to measure heat exposure, both to directly study the health effects of outdoor temperature and to control for temperature in studies of other environmental exposures, including air pollution. To measure heat exposure, environmental health studies often use heat index, which incorporates both air temperature and moisture. However, the method of calculating heat index varies across environmental studies, which could mean that studies using different algorithms to calculate heat index may not be comparable. Objective and Methods: We investigated 21 separate heat index algorithms found in the literature to determine a) whether different algorithms generate heat index values that are consistent with the theoretical concepts of apparent temperature and b) whether different algorithms generate similar heat index values. Results: Although environmental studies differ in how they calculate heat index values, most studies’ heat index algorithms generate values consistent with apparent temperature. Additionally, most different algorithms generate closely correlated heat index values. However, a few algorithms are potentially problematic, especially in certain weather conditions (e.g., very low relative humidity, cold weather). To aid environmental health researchers, we have created open-source software in R to calculate the heat index using the U.S. National Weather Service’s algorithm. Conclusion: We identified 21 separate heat index algorithms used in environmental research. Our analysis demonstrated that methods to calculate heat index are inconsistent across studies. Careful choice of a heat index algorithm can help ensure reproducible and consistent environmental health research. Citation: Anderson GB, Bell ML, Peng RD. 2013. Methods to calculate the heat index as an exposure metric in environmental health research. Environ Health Perspect 121:1111–1119; http://dx.doi.org/10.1289/ehp.1206273 PMID:23934704

Effect of location in an array on heat transfer to a cylinder in crossflow

NASA Technical Reports Server (NTRS)

Simoneau, R. J.; Vanfossen, G. J., Jr.

1982-01-01

An experiment was conducted to measure the heat transfer from a heated cylinder in crossflow in an array of circular cylinders. All cylinders had a length-to-diameter ratio of 3.0. Both in-line and staggered array patterns were studied. The cylinders were spaced 2.67 diameters apart center-to-center in both the axial and transverse directions to the flow. The row containing the heated cylinder remained in a fixed position in the channel and the relative location of this row within the array was changed by adding up to five upstream rows. The working fluid was nitrogen gas at pressures from 100 to 600 kPa. The Reynolds number ranged based on cylinder diameter and average unobstructed channel velocity was from 5,000 to 125,000. Turbulence intensity: profiles were measured for each case at a point one half space upstream of the row containing the heated cylinder. The basis of comparison for all the heat transfer data was the single row with the heated cylinder. For the in-line cases the addition of a single row of cylinders upstream of the row containing the heated cylinder increased the heat transfer by an average of 50 percent above the base case. Adding up to five more rows caused no increase or decrease in heat transfer. Adding rows in the staggered array cases resulted in average increases in heat transfer of 21, 64, 58, 46, and 46 percent for one to five upstream rows, respectively.

An experimental study on the thermal characteristics and heating effect of arc-fault from Cu core in residential electrical wiring fires

PubMed Central

Du, Jian-Hua; Zeng, Yi; Pan, Leng; Zhang, Ren-Cheng

2017-01-01

The characteristics of a series direct current (DC) arc-fault including both electrical and thermal parameters were investigated based on an arc-fault simulator to provide references for multi-parameter electrical fire detection method. Tests on arc fault behavior with three different initial circuit voltages, resistances and arc gaps were conducted, respectively. The influences of circuit conditions on arc dynamic image, voltage, current or power were interpreted. Also, the temperature rises of electrode surface and ambient air were studied. The results showed that, first, significant variations of arc structure and light emitting were observed under different conditions. A thin outer burning layer of vapor generated from electrodes with orange light was found due to the extremely high arc temperature. Second, with the increasing electrode gap in discharging, the arc power was shown to have a non monotonic relationship with arc length for constant initial circuit voltage and resistance. Finally, the temperature rises of electrode surface caused by heat transfer from arc were found to be not sensitive with increasing arc length due to special heat transfer mechanism. In addition, temperature of ambient air showed a large gradient in radial direction of arc. PMID:28797055

An experimental study on the thermal characteristics and heating effect of arc-fault from Cu core in residential electrical wiring fires.

PubMed

Du, Jian-Hua; Tu, Ran; Zeng, Yi; Pan, Leng; Zhang, Ren-Cheng

2017-01-01

The characteristics of a series direct current (DC) arc-fault including both electrical and thermal parameters were investigated based on an arc-fault simulator to provide references for multi-parameter electrical fire detection method. Tests on arc fault behavior with three different initial circuit voltages, resistances and arc gaps were conducted, respectively. The influences of circuit conditions on arc dynamic image, voltage, current or power were interpreted. Also, the temperature rises of electrode surface and ambient air were studied. The results showed that, first, significant variations of arc structure and light emitting were observed under different conditions. A thin outer burning layer of vapor generated from electrodes with orange light was found due to the extremely high arc temperature. Second, with the increasing electrode gap in discharging, the arc power was shown to have a non monotonic relationship with arc length for constant initial circuit voltage and resistance. Finally, the temperature rises of electrode surface caused by heat transfer from arc were found to be not sensitive with increasing arc length due to special heat transfer mechanism. In addition, temperature of ambient air showed a large gradient in radial direction of arc.

Microwave Regenerable Air Purification Device

NASA Technical Reports Server (NTRS)

Atwater, James E.; Holtsnider, John T.; Wheeler, Richard R., Jr.

1996-01-01

The feasibility of using microwave power to thermally regenerate sorbents loaded with water vapor, CO2, and organic contaminants has been rigorously demonstrated. Sorbents challenged with air containing 0.5% CO2, 300 ppm acetone, 50 ppm trichloroethylene, and saturated with water vapor have been regenerated, singly and in combination. Microwave transmission, reflection, and phase shift has also been determined for a variety of sorbents over the frequency range between 1.3-2.7 GHz. This innovative technology offers the potential for significant energy savings in comparison to current resistive heating methods because energy is absorbed directly by the material to be heated. Conductive, convective and radiative losses are minimized. Extremely rapid heating is also possible, i.e., 1400 C in less than 60 seconds. Microwave powered thermal desorption is directly applicable to the needs of Advance Life Support in general, and of EVA in particular. Additionally, the applicability of two specific commercial applications arising from this technology have been demonstrated: the recovery for re-use of acetone (and similar solvents) from industrial waste streams using a carbon based molecular sieve; and the separation and destruction of trichloroethylene using ZSM-5 synthetic zeolite catalyst, a predominant halocarbon environmental contaminant. Based upon these results, Phase II development is strongly recommended.

Noise Reduction Based on an Fe -Rh Interlayer in Exchange-Coupled Heat-Assisted Recording Media

NASA Astrophysics Data System (ADS)

Vogler, Christoph; Abert, Claas; Bruckner, Florian; Suess, Dieter

2017-11-01

High storage density and high data rate are two of the most desired properties of modern hard disk drives. Heat-assisted magnetic recording (HAMR) is believed to achieve both. Recording media, consisting of exchange-coupled grains with a high and a low TC part, were shown to have low dc noise—but increased ac noise—compared to hard magnetic single-phase grains like FePt. We extensively investigate the influence of an Fe -Rh interlayer on the magnetic noise in exchange-coupled grains. We find an optimal grain design that reduces the jitter in the down-track direction by up to 30% and in the off-track direction by up to 50%, depending on the head velocity, compared to the same structures without FeRh. Furthermore, the mechanisms causing this jitter reduction are demonstrated. Additionally, we show that, for short heat pulses and low write temperatures, the switching-time distribution of the analyzed grain structure is reduced by a factor of 4 compared to the same structure without an Fe -Rh layer. This feature could be interesting for HAMR use with a pulsed laser spot and could encourage discussion of this HAMR technique.

Experimental results from plasma transport on Prototype-Material Plasma Exposure eXperiment and comparison with B2-Eirene modeling

NASA Astrophysics Data System (ADS)

Kafle, N.; Caneses, J. F.; Biewer, T. M.; Owen, L.; Showers, M.; Donovan, D.; Caughman, J. B.; Goulding, R. H.; Rapp, Juergen

2017-10-01

Proto-MPEX at ORNL is a linear plasma device that combines a helicon plasma source with additional microwave and RF heating to deliver high plasma heat and particle fluxes to a target. Double Langmuir probes and Thomson scattering are being used to measure local Te and ne at various radial and axial locations. A recently constructed Mach- double probe provides the added capability of simultaneously measuring Te, ne, and Mach number. With this diagnostic, it is possible to infer the plasma flow, particle flux, and convective heat flux at different locations along the plasma column in Proto-MPEX. Preliminary results show Mach numbers of 0.6 and 0.8 in either direction away from the helicon source, and no flow near the source for the case where the peak magnetic field was 1.0 T. In addition, the Thomson Scattering system has been upgraded to measure ne and Te profiles at two axial locations, upstream at the electron heating location and downstream close to the target. Measurements of particle flow and flux profiles, heat flux, and profiles of ne and Te will be discussed. The extensive coverage provided by these diagnostics permits data-constrained B2-Eirene modeling of the entire plasma column, and comparison with results of modeling of high density mode plasmas will be presented. Supported by the US. D.O.E. contract DE-AC05-00OR22725.

Electrical assembly having heat sink protrusions

DOEpatents

Rinehart, Lawrence E.; Romero, Guillermo L.

2009-04-21

An electrical assembly, comprising a heat producing semiconductor device supported on a first major surface of a direct bond metal substrate that has a set of heat sink protrusions supported by its second major surface. In one preferred embodiment the heat sink protrusions are made of the same metal as is used in the direct bond copper.

Climate Adaptivity and Field Test of the Space Heating Used Air-Source Transcritical CO2 Heat Pump

NASA Astrophysics Data System (ADS)

Song, Yulong; Ye, Zuliang; Cao, Feng

2017-08-01

In this study, an innovation of air-sourced transcritical CO2 heat pump which was employed in the space heating application was presented and discussed in order to solve the problem that the heating performances of the transcritical CO2 heat pump water heater deteriorated sharply with the augment in water feed temperature. An R134a cycle was adopted as a subcooling device in the proposed system. The prototype of the presented system was installed and supplied hot water for three places in northern China in winter. The field test results showed that the acceptable return water temperature can be increased up to 55°C, while the supply water temperature was raised rapidly by the presented prototype to up to 70°C directly, which was obviously appropriate to the various conditions of heating radiator in space heating application. Additionally, though the heating capacity and power dissipation decreased with the decline in ambient temperature or the augment in water temperature, the presented heat pump system performed efficiently whatever the climate and water feed temperature were. The real time COP of the presented system was generally more than 1.8 in the whole heating season, while the seasonal performance coefficient (SPC) was also appreciable, which signified that the economic efficiency of the presented system was more excellent than other space heating approaches such as fuel, gas, coal or electric boiler. As a result, the novel system will be a promising project to solve the energy issues in future space heating application.

Axial flow heat exchanger devices and methods for heat transfer using axial flow devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koplow, Jeffrey P.

Systems and methods described herein are directed to rotary heat exchangers configured to transfer heat to a heat transfer medium flowing in substantially axial direction within the heat exchangers. Exemplary heat exchangers include a heat conducting structure which is configured to be in thermal contact with a thermal load or a thermal sink, and a heat transfer structure rotatably coupled to the heat conducting structure to form a gap region between the heat conducting structure and the heat transfer structure, the heat transfer structure being configured to rotate during operation of the device. In example devices heat may be transferredmore » across the gap region from a heated axial flow of the heat transfer medium to a cool stationary heat conducting structure, or from a heated stationary conducting structure to a cool axial flow of the heat transfer medium.« less

Investigation on Active Thermal Control Method with Pool Boiling Heat Transfer at Low Pressure

NASA Astrophysics Data System (ADS)

Sun, Chuang; Guo, Dong; Wang, Zhengyu; Sun, Fengxian

2018-06-01

In order to maintain a desirable temperature level of electronic equipment at low pressure, the thermal control performance with pool boiling heat transfer of water was examined based on experimental measurement. The total setup was designed and performed to accomplish the experiment with the pressure range from 4.5 kPa to 20 kPa and the heat flux between 6 kW/m2 and 20 kW/m2. The chosen material of the heat surface was aluminium alloy and the test cavity had the capability of varying the direction for the heat surface from vertical to horizontal directions. Through this study, the steady and transient temperature of the heat surface at different pressures and directions were obtained. Although the temperature non-uniformity of the heat surface from the centre to the edge could reach 10°C for the aluminium alloy due to the varying pressures, the whole temperature results successfully satisfied with the thermal control requirements for electronic equipment, and the temperature control effect of the vertically oriented direction was better than that of the horizontally oriented direction. Moreover, the behaviour of bubbles generating and detaching from the heat surface was recorded by a high-resolution camera, so as to understand the pool boiling heat transfer mechanism at low-load heat flux. These pictures showed that the bubbles departure diameter becomes larger, and departure frequency was slower at low pressure, in contrast to 1.0 atm.

Multiphysics Computational Analysis of a Solid-Core Nuclear Thermal Engine Thrust Chamber

NASA Technical Reports Server (NTRS)

Wang, Ten-See; Canabal, Francisco; Cheng, Gary; Chen, Yen-Sen

2007-01-01

The objective of this effort is to develop an efficient and accurate computational heat transfer methodology to predict thermal, fluid, and hydrogen environments for a hypothetical solid-core, nuclear thermal engine - the Small Engine. In addition, the effects of power profile and hydrogen conversion on heat transfer efficiency and thrust performance were also investigated. The computational methodology is based on an unstructured-grid, pressure-based, all speeds, chemically reacting, computational fluid dynamics platform, while formulations of conjugate heat transfer were implemented to describe the heat transfer from solid to hydrogen inside the solid-core reactor. The computational domain covers the entire thrust chamber so that the afore-mentioned heat transfer effects impact the thrust performance directly. The result shows that the computed core-exit gas temperature, specific impulse, and core pressure drop agree well with those of design data for the Small Engine. Finite-rate chemistry is very important in predicting the proper energy balance as naturally occurring hydrogen decomposition is endothermic. Locally strong hydrogen conversion associated with centralized power profile gives poor heat transfer efficiency and lower thrust performance. On the other hand, uniform hydrogen conversion associated with a more uniform radial power profile achieves higher heat transfer efficiency, and higher thrust performance.

Heat guiding and focusing using ballistic phonon transport in phononic nanostructures

NASA Astrophysics Data System (ADS)

Anufriev, Roman; Ramiere, Aymeric; Maire, Jeremie; Nomura, Masahiro

2017-05-01

Unlike classical heat diffusion at macroscale, nanoscale heat conduction can occur without energy dissipation because phonons can ballistically travel in straight lines for hundreds of nanometres. Nevertheless, despite recent experimental evidence of such ballistic phonon transport, control over its directionality, and thus its practical use, remains a challenge, as the directions of individual phonons are chaotic. Here, we show a method to control the directionality of ballistic phonon transport using silicon membranes with arrays of holes. First, we demonstrate that the arrays of holes form fluxes of phonons oriented in the same direction. Next, we use these nanostructures as directional sources of ballistic phonons and couple the emitted phonons into nanowires. Finally, we introduce thermal lens nanostructures, in which the emitted phonons converge at the focal point, thus focusing heat into a spot of a few hundred nanometres. These results motivate the concept of ray-like heat manipulations at the nanoscale.

Heat guiding and focusing using ballistic phonon transport in phononic nanostructures.

PubMed

Anufriev, Roman; Ramiere, Aymeric; Maire, Jeremie; Nomura, Masahiro

2017-05-18

Unlike classical heat diffusion at macroscale, nanoscale heat conduction can occur without energy dissipation because phonons can ballistically travel in straight lines for hundreds of nanometres. Nevertheless, despite recent experimental evidence of such ballistic phonon transport, control over its directionality, and thus its practical use, remains a challenge, as the directions of individual phonons are chaotic. Here, we show a method to control the directionality of ballistic phonon transport using silicon membranes with arrays of holes. First, we demonstrate that the arrays of holes form fluxes of phonons oriented in the same direction. Next, we use these nanostructures as directional sources of ballistic phonons and couple the emitted phonons into nanowires. Finally, we introduce thermal lens nanostructures, in which the emitted phonons converge at the focal point, thus focusing heat into a spot of a few hundred nanometres. These results motivate the concept of ray-like heat manipulations at the nanoscale.

Heat guiding and focusing using ballistic phonon transport in phononic nanostructures

PubMed Central

Anufriev, Roman; Ramiere, Aymeric; Maire, Jeremie; Nomura, Masahiro

2017-01-01

Unlike classical heat diffusion at macroscale, nanoscale heat conduction can occur without energy dissipation because phonons can ballistically travel in straight lines for hundreds of nanometres. Nevertheless, despite recent experimental evidence of such ballistic phonon transport, control over its directionality, and thus its practical use, remains a challenge, as the directions of individual phonons are chaotic. Here, we show a method to control the directionality of ballistic phonon transport using silicon membranes with arrays of holes. First, we demonstrate that the arrays of holes form fluxes of phonons oriented in the same direction. Next, we use these nanostructures as directional sources of ballistic phonons and couple the emitted phonons into nanowires. Finally, we introduce thermal lens nanostructures, in which the emitted phonons converge at the focal point, thus focusing heat into a spot of a few hundred nanometres. These results motivate the concept of ray-like heat manipulations at the nanoscale. PMID:28516909

Measurement of a surface heat flux and temperature

NASA Astrophysics Data System (ADS)

Davis, R. M.; Antoine, G. J.; Diller, T. E.; Wicks, A. L.

1994-04-01

The Heat Flux Microsensor is a new sensor which was recently patented by Virginia Tech and is just starting to be marketed by Vatell Corp. The sensor is made using the thin-film microfabrication techniques directly on the material that is to be measured. It consists of several thin-film layers forming a differential thermopile across a thermal resistance layer. The measured heat flux q is proportional to the temperature difference across the resistance layer q= k(sub g)/delta(sub g) x (t(sub 1) - T(sub 2)), where k(sub g) is the thermal conductivity and delta (sub g) is the thickness of the thermal resistance layer. Because the gages are sputter coated directly onto the surface, their total thickness is less than 2 micrometers, which is two orders of magnitude thinner than previous gages. The resulting temperature difference across the thermal resistance layer (delta is less than 1 micrometer) is very small even at high heat fluxes. To generate a measurable signal many thermocouple pairs are put in series to form a differential thermopile. The combination of series thermocouple junctions and thin-film design creates a gage with very attractive characteristics. It is not only physically non-intrusive to the flow, but also causes minimal disruption of the surface temperature. Because it is so thin, the response time is less than 20 microsec. Consequently, the frequency response is flat from 0 to over 50 kHz. Moreover, the signal of the Heat Flux Microsensor is directly proportional to the heat flux. Therefore, it can easily be used in both steady and transient flows, and it measures both the steady and unsteady components of the surface heat flux. A version of the Heat Flux Microsensor has been developed to meet the harsh demands of combustion environments. These gages use platinum and platinum-10 percent rhodium as the thermoelectric materials. The thermal resistance layer is silicon monoxide and a protective coating of Al2O3 is deposited on top of the sensor. The superimposed thin-film pattern of all six layers is presented. The large pads are for connection with pins used to bring the signal out the back of the ceramic.

Measurement of a surface heat flux and temperature

NASA Technical Reports Server (NTRS)

Davis, R. M.; Antoine, G. J.; Diller, T. E.; Wicks, A. L.

1994-01-01

The Heat Flux Microsensor is a new sensor which was recently patented by Virginia Tech and is just starting to be marketed by Vatell Corp. The sensor is made using the thin-film microfabrication techniques directly on the material that is to be measured. It consists of several thin-film layers forming a differential thermopile across a thermal resistance layer. The measured heat flux q is proportional to the temperature difference across the resistance layer q= k(sub g)/delta(sub g) x (t(sub 1) - T(sub 2)), where k(sub g) is the thermal conductivity and delta (sub g) is the thickness of the thermal resistance layer. Because the gages are sputter coated directly onto the surface, their total thickness is less than 2 micrometers, which is two orders of magnitude thinner than previous gages. The resulting temperature difference across the thermal resistance layer (delta is less than 1 micrometer) is very small even at high heat fluxes. To generate a measurable signal many thermocouple pairs are put in series to form a differential thermopile. The combination of series thermocouple junctions and thin-film design creates a gage with very attractive characteristics. It is not only physically non-intrusive to the flow, but also causes minimal disruption of the surface temperature. Because it is so thin, the response time is less than 20 microsec. Consequently, the frequency response is flat from 0 to over 50 kHz. Moreover, the signal of the Heat Flux Microsensor is directly proportional to the heat flux. Therefore, it can easily be used in both steady and transient flows, and it measures both the steady and unsteady components of the surface heat flux. A version of the Heat Flux Microsensor has been developed to meet the harsh demands of combustion environments. These gages use platinum and platinum-10 percent rhodium as the thermoelectric materials. The thermal resistance layer is silicon monoxide and a protective coating of Al2O3 is deposited on top of the sensor. The superimposed thin-film pattern of all six layers is presented. The large pads are for connection with pins used to bring the signal out the back of the ceramic. In addition to the heat flux measurement, the surface temperature is measured with a platinum resistance layer (RTS). The resistance of this layer increases with increasing temperature. Therefore, these gages simultaneously measure the surface temperature and heat flux. The demonstrated applications include rocket nozzles, SCRAM jet engines, gas turbine engines, boiling heat transfer, flame experiments, basic fluid heat transfer, hypersonic flight, and shock tube testing. The laboratory involves using one of these sensors in a small combustion flame. The sensor is made on a 2.5 cm diameter piece of aluminum nitride ceramic.

Open-cycle magnetohydrodynamic power plant based upon direct-contact closed-loop high-temperature heat exchanger

DOEpatents

Berry, G.F.; Minkov, V.; Petrick, M.

1981-11-02

A magnetohydrodynamic (MHD) power generating system is described in which ionized combustion gases with slag and seed are discharged from an MHD combustor and pressurized high temperature inlet air is introduced into the combustor for supporting fuel combustion at high temperatures necessary to ionize the combustion gases, and including a heat exchanger in the form of a continuous loop with a circulating heat transfer liquid such as copper oxide. The heat exchanger has an upper horizontal channel for providing direct contact between the heat transfer liquid and the combustion gases to cool the gases and condense the slag which thereupon floats on the heat transfer liquid and can be removed from the channel, and a lower horizontal channel for providing direct contact between the heat transfer liquid and pressurized air for preheating the inlet air. The system further includes a seed separator downstream of the heat exchanger.

Open-cycle magnetohydrodynamic power plant based upon direct-contact closed-loop high-temperature heat exchanger

DOEpatents

Berry, Gregory F.; Minkov, Vladimir; Petrick, Michael

1988-01-05

A magnetohydrodynamic (MHD) power generating system in which ionized combustion gases with slag and seed are discharged from an MHD combustor and pressurized high temperature inlet air is introduced into the combustor for supporting fuel combustion at high temperatures necessary to ionize the combustion gases, and including a heat exchanger in the form of a continuous loop with a circulating heat transfer liquid such as copper oxide. The heat exchanger has an upper horizontal channel for providing direct contact between the heat transfer liquid and the combustion gases to cool the gases and condense the slag which thereupon floats on the heat transfer liquid and can be removed from the channel, and a lower horizontal channel for providing direct contact between the heat transfer liquid and pressurized air for preheating the inlet air. The system further includes a seed separator downstream of the heat exchanger.

Open-cycle magnetohydrodynamic power plant based upon direct-contact closed-loop high-temperature heat exchanger

DOEpatents

Berry, Gregory F.; Minkov, Vladimir; Petrick, Michael

1988-01-01

A magnetohydrodynamic (MHD) power generating system in which ionized combustion gases with slag and seed are discharged from an MHD combustor and pressurized high temperature inlet air is introduced into the combustor for supporting fuel combustion at high temperatures necessary to ionize the combustion gases, and including a heat exchanger in the form of a continuous loop with a circulating heat transfer liquid such as copper oxide. The heat exchanger has an upper horizontal channel for providing direct contact between the heat transfer liquid and the combustion gases to cool the gases and condense the slag which thereupon floats on the heat transfer liquid and can be removed from the channel, and a lower horizontal channel for providing direct contact between the heat transfer liquid and pressurized air for preheating the inlet air. The system further includes a seed separator downstream of the heat exchanger.

Molecular diagnostics of FUV and accretion-related heating in protoplanetary disks

NASA Astrophysics Data System (ADS)

Adamkovics, Mate; Najita, Joan R.

2017-10-01

Emission lines from the terrestrial planet forming regions of disks are diagnostic of both the physical processes that heat the gas and the chemistry that determines the inventory of nebular material available during the epoch of planet formation. Interpreting emission spectra is informed by models of radiative, thermal, physical, and chemical processes, such as: (i) the radiation transfer of X-rays and FUV --- both continuum and Ly-alpha, (ii) direct and indirect heating processes such as the photoelectric effect and photochemical heating, (iii) heating related to turbulent processes and viscous dissipation, and (iv) gas phase chemical reaction kinetics. Many of these processes depend on a the spatial distribution of dust grains and their properties, which temporally evolve during the lifetime of the disk and the formation of planets. Studies of disks atmospheres often predict a layered structure of hot (a few thousand K) atomic gas overlying warm (a few hundred K) molecular gas, which is generally consistent with the isothermal slab emission models that are used to interpret emission spectra. However, detailed comparison between observed spectra and models (e.g., comparing the total columns and the radial extent of warm emitting species) is rare.We present results including the implementation of Ly-alpha scattering, which is an important part of the photochemical heating and FUV heating radiation budget. By including these processes we find a new component of the disk atmosphere; hot molecular gas at ~2000K within radial distances of ~0.5AU, which is consistent with observations of UV-fluorescent H2 emission (Ádámkovics, Najita & Glassgold, 2016). Constraining the most optimistic contribution of radiative heating mechanisms via X-rays and FUV together with a favorable comparison to observations, allows us to explore and evaluate additional heating mechanisms. We find that the total columns of warm (90-400K) emitting molecules such as CO, arising directly below the irradiated molecular layer, are diagnostic of the role of turbulent (viscous) mechanical heating. We discuss how the total columns of warm molecules in this layer may be diagnostic of the magnetorotational instability (Najita & Ádámkovics, 2017).

Water-tunnel studies of heat balance in swimming mako sharks.

PubMed

Bernal, D; Sepulveda, C; Graham, J B

2001-12-01

The mako shark (Isurus oxyrinchus) has specialized vascular networks (retia mirabilia) forming counter-current heat exchangers that allow metabolic heat retention in certain regions of the body, including the aerobic, locomotor red muscle and the viscera. Red muscle, white muscle and stomach temperatures were measured in juvenile (5-13.6 kg) makos swimming steadily in a water tunnel and exposed to stepwise square-wave changes in ambient temperature (T(a)) to estimate the rates of heat transfer and to determine their capacity for the activity-independent control of heat balance. The rates of heat gain of red muscle during warming were significantly higher than the rates of heat loss during cooling, and neither the magnitude of the change in T(a) nor the direction of change in T(a) had a significant effect on red muscle latency time. Our findings for mako red muscle are similar to those recorded for tunas and suggest modulation of retial heat-exchange efficiency as the underlying mechanism controlling heat balance. However, the red muscle temperatures measured in swimming makos (0.3-3 degrees C above T(a)) are cooler than those measured previously in larger decked makos. Also, the finding of non-stable stomach temperatures contrasts with the predicted independence from T(a) recorded in telemetry studies of mako and white sharks. Our studies on live makos provide new evidence that, in addition to the unique convergent morphological properties between makos and tunas, there is a strong functional similarity in the mechanisms used to regulate heat transfer.

Boundary Waves on the Ice Surface Created by Currents

NASA Astrophysics Data System (ADS)

Naito, K.; Izumi, N.; Yokokawa, M.; Yamada, T.; de Lima, A. C.

2013-12-01

The formation of periodic boundary waves, e.g. antidunes and cyclic steps (Parker & Izumi 2000) has been known to be caused by instabilities between flow and bed (e.g. Engelund 1970), and are observed not only on river beds or ocean floors but also on ice surfaces, such as the surface of glaciers and underside of river ice (Carey 1966). In addition, owing to recent advancements of remote sensing technology, it has been found that the surfaces of the polar ice caps on Mars as well as on the Earth have step-like formations (Smith & Holt 2010) which are assumed to be boundary waves, because they are generated perpendicularly to the direction of the currents. These currents acting on the polar ice caps are density airflow, i.e. katabatic wind (Howard et al 2000). The comprehension of the formation process of the Martian polar ice caps may reveal climate changes which have occurred on Mars. Although the formation of boundary waves on river beds or ocean floors has been studied by a number of researchers, there are few works on their formation on ice surfaces. Yokokawa et al (2013) suggested that the temperature distribution of the ambient air, fluid and ice is a factor which determines the direction of migration of boundary waves formed on ice surfaces through their experiments. In this study, we propose a mathematical model in order to describe the formation process of the boundary waves and the direction of their migration. We consider that a liquid is flowing through a flume filled with a flat ice layer on the bottom. The flow is assumed to be turbulent and its temperature is assumed to merge with the ambient temperature at the flow surface and with the melting point of ice at the bottom (ice surface). The ice surface evolution is dependent on the unbalance between the interfacial heat flux of the liquid and ice, and we employ the Reynolds-averaged Navier-Stokes equation, the continuity equation, heat transfer equations for the liquid and ice, and a heat balance equation at the flow-ice interface. It is assumed that the interfacial heat fluxes of the liquid and ice are determined by the temperature profile, and the Reynolds stress and the turbulent heat flux are expressed by the eddy diffusivity of momentum and the eddy diffusivity of heat, respectively. In addition, the liquid can be divided into two layers; viscous sublayer and turbulent layer. In order to determine the velocity and temperature profile in the liquid, we employ the Prandtl-Taylor analogy which assumes that the velocity profile follows a linear law in the viscous sublayer and a logarithmic law in the turbulent layer, and the eddy diffusivity of heat is described by the eddy diffusivity of momentum and Prandtl number of the liquid. Finally, we obtain the temperature profiles (because the heat transfer equation for the ice reduces to the Laplace equation, the temperature profile in the ice can be easily estimated) and interfacial heat fluxes.

Energy Savings Calculations for Heat Island Reduction Strategies in Baton Rouge, Sacramento and Salt Lake City

DOE Office of Scientific and Technical Information (OSTI.GOV)

Konopacki, S.; Akbari, H.

2000-03-01

In 1997, the US Environmental Protection Agency (EPA) established the ''Heat Island Reduction Initiative'', to quantify the potential benefits of Heat Island Reduction (HIR) strategies (i.e., shade trees, reflective roofs, reflective pavements and urban vegetation) to reduce cooling energy use in buildings, lower the ambient air temperature and improve urban air quality in cities, and reduce CO2 emissions from power plants. Under this initiative, the Urban Heat Island Pilot Project (UHIPP) was created with the objective to investigate the potential of HIR strategies in residential and commercial buildings in three initial UHIPP cities: Baton Rouge, Sacramento and Salt Lake City.more » This paper summarizes our efforts to calculate the annual energy savings, peak power avoidance and annual C02 reduction of HIR strategies in the three initial cities. In this analysis, we focused on three building types that offer most savings potential: single-family residence, office and retail store. Each building type was characterized in detail by old or new construction and with a gas furnace or an electric heat pump. We defined prototypical building characteristics for each building type and simulated the impact of HIR strategies on building cooling and heating energy use and peak power demand using the DOE-2.IE model. Our simulations included the impact of (1) strategically-placed shade trees near buildings [direct effect], (2) use of high-albedo roofing material on building [direct effect], (3) combined strategies I and 2 [direct effect], (4) urban reforestation with high-albedo pavements and building surfaces [indirect effect] and (5) combined strategies 1, 2 and 4 [direct and indirect effects]. We then estimated the total roof area of air-conditioned buildings in each city using readily obtainable data to calculate the metropolitan-wide impact of HIR strategies. The results show, that in Baton Rouge, potential annual energy savings of $15M could be realized by rate-payers from the combined direct and indirect effects of HIR strategies. Additionally, peak power avoidance is estimated at 133 MW and the reduction in annual carbon emissions at 41 kt. In Sacramento, the potential annual energy savings is estimated at $26M, with an avoidance of 486 MW in peak power and a reduction in annual carbon of 92 kt. In Salt Lake City, the potential annual energy savings is estimated at $4M, with an avoidance of 85 MW in peak power and a reduction in annual carbon of 20 kt.« less

After heat distribution of a mobile nuclear power plant

NASA Technical Reports Server (NTRS)

Parker, W. G.; Vanbibber, L. E.; Tang, Y. S.

1971-01-01

A computer program was developed to analyze the transient afterheat temperature and pressure response of a mobile gas-cooled reactor power plant following impact. The program considers (in addition to the standard modes of heat transfer) fission product decay and transport, metal-water reactions, core and shield melting and displacement, and pressure and containment vessel stress response. Analyses were performed for eight cases (both deformed and undeformed models) to verify operability of the program options. The results indicated that for a 350 psi (241 n/sq cm) initial internal pressure, the containment vessel can survive over 100,000 seconds following impact before creep rupture occurs. Recommendations were developed as to directions for redesign to extend containment vessel life.

Experimental evidence of thermal vibrational convection in a nonuniformly heated fluid in a reduced gravity environment.

PubMed

Mialdun, A; Ryzhkov, I I; Melnikov, D E; Shevtsova, V

2008-08-22

We report experimental evidence of convection caused by translational vibration of nonuniformly heated fluid in low gravity. The theory of vibrational convection in weightlessness is well developed but direct experimental proof has been missing. An innovative point of the experiment is the observation of a temperature field in the front and side views of the cubic cell. In addition, particle tracing is employed. The evolution of this field is studied systematically in a wide range of frequencies and amplitudes. The flow structures reported in previous numerical studies are confirmed. The transition from four-vortex flow to the pattern with three vortices is observed in the transient state.

Preliminary Studies on Aerodynamic Control with Direct Current Discharge at Hypersonic Speed

NASA Astrophysics Data System (ADS)

Watanabe, Yasumasa; Takama, Yoshiki; Imamura, Osamu; Watanuki, Tadaharu; Suzuki, Kojiro

A new idea of an aerodynamic control device for hypersonic vehicles using plasma discharges is presented. The effect of DC plasma discharge on a hypersonic flow is examined with both experiments and CFD analyses. It is revealed that the surface pressure upstream of plasma area significantly increases, which would be preferable in realizing a new aerodynamic control devices. Such pressure rise is also observed in the result of analyses of the Navier-Stokes equations with energy addition that simulates the Joule heating of a plasma discharge. It is revealed that the pressure rise due to the existence of the plasma discharge can be qualitatively explained as an effect of Joule heating.

Thin Thermoelectric Generator System for Body Energy Harvesting

NASA Astrophysics Data System (ADS)

Settaluri, Krishna T.; Lo, Hsinyi; Ram, Rajeev J.

2012-06-01

Wearable thermoelectric generators (TEGs) harvest thermal energy generated by the body to generate useful electricity. The performance of these systems is limited by (1) the small working temperature differential between the body and ambient, (2) the desire to use natural air convection cooling on the cold side of the generator, and (3) the requirement for thin, lightweight systems that are comfortable for long-term use. Our work has focused on the design of the heat transfer system as part of the overall thermoelectric (TE) system. In particular, the small heat transfer coefficient for natural air convection results in a module thermal impedance that is smaller than that of the heat sink. In this heat-sink-limited regime, the thermal resistance of the generator should be optimized to match that of the heat sink to achieve the best performance. In addition, we have designed flat (1 mm thickness) copper heat spreaders to realize performance surpassing splayed pin heat sinks. Two-dimensional (2-D) heat spreading exploits the large surface area available in a wristband and allows patterned copper to efficiently cool the TE. A direct current (DC)/DC converter is integrated on the wristband. The system generates up to 28.5 μW/cm2 before the converter and 8.6 μW/cm2 after the converter, with 30% efficiency. It generates output of 4.15 V with overall thickness under 5 mm.

Immiscible fluid: Heat of fusion heat storage system

NASA Technical Reports Server (NTRS)

Edie, D. D.; Melsheimer, S. S.; Mullins, J. C.

1980-01-01

Both heat and mass transfer in direct contact aqueous crystallizing systems were studied as part of a program desig- ned to evaluate the feasibility of direct contact heat transfer in phase change storage using aqueous salt system. Major research areas, discussed include (1) crystal growth velocity study on selected salts; (2) selection of salt solutions; (3) selection of immiscible fluids; (4) studies of heat transfer and system geometry; and (5) system demonstration.

Predictive modeling of solidification during laser additive manufacturing of nickel superalloys: recent developments, future directions

NASA Astrophysics Data System (ADS)

Ghosh, Supriyo

2018-01-01

Additive manufacturing (AM) processes produce parts with improved physical, chemical, and mechanical properties compared to conventional manufacturing processes. In AM processes, intricate part geometries are produced from multicomponent alloy powder, in a layer-by-layer fashion with multipass laser melting, solidification, and solid-state phase transformations, in a shorter manufacturing time, with minimal surface finishing, and at a reasonable cost. However, there is an increasing need for post-processing of the manufactured parts via, for example, stress relieving heat treatment and hot isostatic pressing to achieve homogeneous microstructure and properties at all times. Solidification in an AM process controls the size, shape, and distribution of the grains, the growth morphology, the elemental segregation and precipitation, the subsequent solid-state phase changes, and ultimately the material properties. The critical issues in this process are linked with multiphysics (such as fluid flow and diffusion of heat and mass) and multiscale (lengths, times and temperature ranges) challenges that arise due to localized rapid heating and cooling during AM processing. The alloy chemistry-process-microstructure-property-performance correlation in this process will be increasingly better understood through multiscale modeling and simulation.

New thermodynamical force in plasma phase space that controls turbulence and turbulent transport.

PubMed

Itoh, Sanae-I; Itoh, Kimitaka

2012-01-01

Physics of turbulence and turbulent transport has been developed on the central dogma that spatial gradients constitute the controlling parameters, such as Reynolds number and Rayleigh number. Recent experiments with the nonequilibrium plasmas in magnetic confinement devices, however, have shown that the turbulence and transport change much faster than global parameters, after an abrupt change of heating power. Here we propose a theory of turbulence in inhomogeneous magnetized plasmas, showing that the heating power directly influences the turbulence. New mechanism, that an external source couples with plasma fluctuations in phase space so as to affect turbulence, is investigated. A new thermodynamical force in phase-space, i.e., the derivative of heating power by plasma pressure, plays the role of new control parameter, in addition to spatial gradients. Following the change of turbulence, turbulent transport is modified accordingly. The condition under which this new effect can be observed is also evaluated.

Turbulent convection in geostrophic circulation with wind and buoyancy forcing

NASA Astrophysics Data System (ADS)

Sohail, Taimoor; Gayen, Bishakhdatta; Hogg, Andy

2017-11-01

We conduct a direct numerical simulation of geostrophic circulation forced by surface wind and buoyancy to model a circumpolar ocean. The imposed buoyancy forcing (represented by Rayleigh number) drives a zonal current and supports small-scale convection in the buoyancy destabilizing region. In addition, we observe eddy activity which transports heat southward, supporting a large amount of heat uptake. Increasing wind stress enhances the meridional buoyancy gradient, triggering more eddy activity inside the boundary layer. Therefore, heat uptake increases with higher wind stress. The majority of dissipation is confined within the surface boundary layer, while mixing is dominant inside the convective plume and the buoyancy destabilizing region of the domain. The relative strength of the mixing and dissipation in the system can be expressed by mixing efficiency. This study finds that mixing is much greater than viscous dissipation, resulting in higher values of mixing efficiency than previously used. Supported by Australian Research Council Grant DP140103706.

Regenerative Fuel Cell Test Rig at Glenn Research Center

NASA Technical Reports Server (NTRS)

Chang, Bei-Jiann; Johnson, Donald W.; Garcia, Christopher P.; Jakupca, Ian J.; Scullin, Vincent J.; Bents, David J.

2003-01-01

The regenerative fuel cell development effort at Glenn Research Center (GRC) involves the integration of a dedicated fuel cell and electrolyzer into an energy storage system test rig. The test rig consists of a fuel cell stack, an electrolysis stack, cooling pumps, a water transfer pump, gas recirculation pumps, phase separators, storage tanks for oxygen (O2) and hydrogen (H2), heat exchangers, isolation valves, pressure regulators, interconnecting tubing, nitrogen purge provisions, and instrumentation for control and monitoring purposes. The regenerative fuel cell (RFC) thus formed is a completely closed system which is capable of autonomous cyclic operation. The test rig provides direct current (DC) load and DC power supply to simulate power consumption and solar power input. In addition, chillers are used as the heat sink to dissipate the waste heat from the electrochemical stack operation. Various vents and nitrogen (N2) sources are included in case inert purging is necessary to safe the RFC test rig.

Forced-flow once-through boilers. [structural design criteria/aerospace environments

NASA Technical Reports Server (NTRS)

Stone, J. R.; Gray, V. H.; Gutierrez, O. A.

1975-01-01

A compilation and review of NASA-sponsored research on boilers for use in spacecraft electrical power generation systems is presented. Emphasis is on the heat-transfer and fluid-flow problems. In addition to space applications, much of the boiler technology is applicable to terrestrial and marine uses such as vehicular power, electrical power generation, vapor generation, and heating and cooling. Related research areas are discussed such as condensation, cavitation, line and boiler dynamics, the SNAP-8 project (Mercury-Rankine cycle), and conventional terrestrial boilers (either supercritical or gravity-assisted liquid-vapor separation types). The research effort was directed at developing the technology for once-through compact boilers with high heat fluxes to generate dry vapor stably, without utilizing gravity for phase separations. A background section that discusses, tutorially, the complex aspects of the boiling process is presented. Discussions of tests on alkali metals are interspersed with those on water and other fluids on a phenomenological basis.

New Thermodynamical Force in Plasma Phase Space that Controls Turbulence and Turbulent Transport

PubMed Central

Itoh, Sanae-I.; Itoh, Kimitaka

2012-01-01

Physics of turbulence and turbulent transport has been developed on the central dogma that spatial gradients constitute the controlling parameters, such as Reynolds number and Rayleigh number. Recent experiments with the nonequilibrium plasmas in magnetic confinement devices, however, have shown that the turbulence and transport change much faster than global parameters, after an abrupt change of heating power. Here we propose a theory of turbulence in inhomogeneous magnetized plasmas, showing that the heating power directly influences the turbulence. New mechanism, that an external source couples with plasma fluctuations in phase space so as to affect turbulence, is investigated. A new thermodynamical force in phase-space, i.e., the derivative of heating power by plasma pressure, plays the role of new control parameter, in addition to spatial gradients. Following the change of turbulence, turbulent transport is modified accordingly. The condition under which this new effect can be observed is also evaluated. PMID:23155481

New Thermodynamical Force in Plasma Phase Space that Controls Turbulence and Turbulent Transport

NASA Astrophysics Data System (ADS)

Itoh, Sanae-I.; Itoh, Kimitaka

2012-11-01

Physics of turbulence and turbulent transport has been developed on the central dogma that spatial gradients constitute the controlling parameters, such as Reynolds number and Rayleigh number. Recent experiments with the nonequilibrium plasmas in magnetic confinement devices, however, have shown that the turbulence and transport change much faster than global parameters, after an abrupt change of heating power. Here we propose a theory of turbulence in inhomogeneous magnetized plasmas, showing that the heating power directly influences the turbulence. New mechanism, that an external source couples with plasma fluctuations in phase space so as to affect turbulence, is investigated. A new thermodynamical force in phase-space, i.e., the derivative of heating power by plasma pressure, plays the role of new control parameter, in addition to spatial gradients. Following the change of turbulence, turbulent transport is modified accordingly. The condition under which this new effect can be observed is also evaluated.

Maximal Oxygen Uptake, Sweating and Tolerance to Exercise in the Heat

NASA Technical Reports Server (NTRS)

Greenleaf, J. E.; Castle, B. L.; Ruff, W. K.

1972-01-01

The physiological mechanisms that facilitate acute acclimation to heat have not been fully elucidated, but the result is the establishment of a more efficient cardiovascular system to increase heat dissipation via increased sweating that allows the acclimated man to function with a cooler internal environment and to extend his performance. Men in good physical condition with high maximal oxygen uptakes generally acclimate to heat more rapidly and retain it longer than men in poorer condition. Also, upon first exposure trained men tolerate exercise in the heat better than untrained men. Both resting in heat and physical training in a cool environment confer only partial acclimation when first exposed to work in the heat. These observations suggest separate additive stimuli of metabolic heat from exercise and environmental heat to increase sweating during the acclimation process. However, the necessity of utilizing physical exercise during acclimation has been questioned. Bradbury et al. (1964) have concluded exercise has no effect on the course of heat acclimation since increased sweating can be induced by merely heating resting subjects. Preliminary evidence suggests there is a direct relationship between the maximal oxygen uptake and the capacity to maintain thermal regulation, particularly through the control of sweating. Since increased sweating is an important mechanism for the development of heat acclimation, and fit men have high sweat rates, it follows that upon initial exposure to exercise in the heat, men with high maximal oxygen uptakes should exhibit less strain than men with lower maximal oxygen uptakes. The purpose of this study was: (1) to determine if men with higher maximal oxygen uptakes exhibit greater tolerance than men with lower oxygen uptakes during early exposure to exercise in the heat, and (2) to investigate further the mechanism of the relationship between sweating and maximal work capacity.

Effect of heating strategies on whey protein denaturation--Revisited by liquid chromatography quadrupole time-of-flight mass spectrometry.

PubMed

Akkerman, M; Rauh, V M; Christensen, M; Johansen, L B; Hammershøj, M; Larsen, L B

2016-01-01

Previous standards in the area of effect of heat treatment processes on milk protein denaturation were based primarily on laboratory-scale analysis and determination of denaturation degrees by, for example, electrophoresis. In this study, whey protein denaturation was revisited by pilot-scale heating strategies and liquid chromatography quadrupole time-of-flight mass spectrometer (LC/MC Q-TOF) analysis. Skim milk was heat treated by the use of 3 heating strategies, namely plate heat exchanger (PHE), tubular heat exchanger (THE), and direct steam injection (DSI), under various heating temperatures (T) and holding times. The effect of heating strategy on the degree of denaturation of β-lactoglobulin and α-lactalbumin was determined using LC/MC Q-TOF of pH 4.5-soluble whey proteins. Furthermore, effect of heating strategy on the rennet-induced coagulation properties was studied by oscillatory rheometry. In addition, rennet-induced coagulation of heat-treated micellar casein concentrate subjected to PHE was studied. For skim milk, the whey protein denaturation increased significantly as T and holding time increased, regardless of heating method. High denaturation degrees were obtained for T >100°C using PHE and THE, whereas DSI resulted in significantly lower denaturation degrees, compared with PHE and THE. Rennet coagulation properties were impaired by increased T and holding time regardless of heating method, although DSI resulted in less impairment compared with PHE and THE. No significant difference was found between THE and PHE for effect on rennet coagulation time, whereas the curd firming rate was significantly larger for THE compared with PHE. Micellar casein concentrate possessed improved rennet coagulation properties compared with skim milk receiving equal heat treatment. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Nanoscale Structural and Mechanical Analysis of Bacillus anthracis Spores Inactivated with Rapid Dry Heating

PubMed Central

Felker, Daniel L.; Burggraf, Larry W.

2014-01-01

Effective killing of Bacillus anthracis spores is of paramount importance to antibioterrorism, food safety, environmental protection, and the medical device industry. Thus, a deeper understanding of the mechanisms of spore resistance and inactivation is highly desired for developing new strategies or improving the known methods for spore destruction. Previous studies have shown that spore inactivation mechanisms differ considerably depending upon the killing agents, such as heat (wet heat, dry heat), UV, ionizing radiation, and chemicals. It is believed that wet heat kills spores by inactivating critical enzymes, while dry heat kills spores by damaging their DNA. Many studies have focused on the biochemical aspects of spore inactivation by dry heat; few have investigated structural damages and changes in spore mechanical properties. In this study, we have inactivated Bacillus anthracis spores with rapid dry heating and performed nanoscale topographical and mechanical analysis of inactivated spores using atomic force microscopy (AFM). Our results revealed significant changes in spore morphology and nanomechanical properties after heat inactivation. In addition, we also found that these changes were different under different heating conditions that produced similar inactivation probabilities (high temperature for short exposure time versus low temperature for long exposure time). We attributed the differences to the differential thermal and mechanical stresses in the spore. The buildup of internal thermal and mechanical stresses may become prominent only in ultrafast, high-temperature heat inactivation when the experimental timescale is too short for heat-generated vapor to efficiently escape from the spore. Our results thus provide direct, visual evidences of the importance of thermal stresses and heat and mass transfer to spore inactivation by very rapid dry heating. PMID:24375142

Multipurpose Vacuum Induction Processing System

NASA Astrophysics Data System (ADS)

Govindaraju, M.; Kulkarni, Deepak; Balasubramanian, K.

2012-11-01

Multipurpose vacuum processing systems are cost effective; occupy less space, multiple functional under one roof and user friendly. A multipurpose vacuum induction system was designed, fabricated and installed in a record time of 6 months time at NFTDC Hyderabad. It was designed to function as a) vacuum induction melting/refining of oxygen free electronic copper/pure metals, b) vacuum induction melting furnace for ferrous materials c) vacuum induction melting for non ferrous materials d) large vacuum heat treatment chamber by resistance heating (by detachable coil and hot zone) e) bottom discharge vacuum induction melting system for non ferrous materials f) Induction heat treatment system and g) directional solidification /investment casting. It contains provision for future capacity addition. The attachments require to manufacture multiple shaped castings and continuous rod casting can be added whenever need arises. Present capacity is decided on the requirement for 10years of development path; presently it has 1.2 ton liquid copper handling capacity. It is equipped with provision for capacity addition up to 2 ton liquid copper handling capacity in future. Provision is made to carry out the capacity addition in easy steps quickly. For easy operational maintenance and troubleshooting, design was made in easily detachable sections. High vacuum system is also is detachable, independent and easily movable which is first of its kind in the country. Detailed design parameters, advantages and development history are presented in this paper.

Process-Structure-Property Relationships for 316L Stainless Steel Fabricated by Additive Manufacturing and Its Implication for Component Engineering

NASA Astrophysics Data System (ADS)

Yang, Nancy; Yee, J.; Zheng, B.; Gaiser, K.; Reynolds, T.; Clemon, L.; Lu, W. Y.; Schoenung, J. M.; Lavernia, E. J.

2017-04-01

We investigate the process-structure-property relationships for 316L stainless steel prototyping utilizing 3-D laser engineered net shaping (LENS), a commercial direct energy deposition additive manufacturing process. The study concluded that the resultant physical metallurgy of 3-D LENS 316L prototypes is dictated by the interactive metallurgical reactions, during instantaneous powder feeding/melting, molten metal flow and liquid metal solidification. The study also showed 3-D LENS manufacturing is capable of building high strength and ductile 316L prototypes due to its fine cellular spacing from fast solidification cooling, and the well-fused epitaxial interfaces at metal flow trails and interpass boundaries. However, without further LENS process control and optimization, the deposits are vulnerable to localized hardness variation attributed to heterogeneous microstructure, i.e., the interpass heat-affected zone (HAZ) from repetitive thermal heating during successive layer depositions. Most significantly, the current deposits exhibit anisotropic tensile behavior, i.e., lower strain and/or premature interpass delamination parallel to build direction (axial). This anisotropic behavior is attributed to the presence of interpass HAZ, which coexists with flying feedstock inclusions and porosity from incomplete molten metal fusion. The current observations and findings contribute to the scientific basis for future process control and optimization necessary for material property control and defect mitigation.

Modelling of Technological Solutions to 4th Generation DH Systems

NASA Astrophysics Data System (ADS)

Vigants, Edgars; Prodanuks, Toms; Vigants, Girts; Veidenbergs, Ivars; Blumberga, Dagnija

2017-11-01

Flue gas evaporation and condensing processes are investigated in a direct contact heat exchanger - condensing unit, which is installed after a furnace. By using equations describing processes of heat and mass transfer, as well as correlation coherences for determining wet gas parameters, a model is formed to create a no-filling, direct contact heat exchanger. Results of heating equipment modelling and experimental research on the gas condensing unit show, that the capacity of the heat exchanger increases, when return temperature of the district heating network decreases. In order to explain these alterations in capacity, the character of the changes in water vapour partial pressure, in the propelling force of mass transfer, in gas and water temperatures and in the determining parameters of heat transfer are used in this article. The positive impact on the direct contact heat exchanger by the decreased district heating (DH) network return temperature shows that introduction of the 4th generation DH system increases the energy efficiency of the heat exchanger. In order to make an assessment, the methodology suggested in the paper can be used in each particular situation.

Geothermal direct use in the United States update: 1990-1994

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lienau, P.J.; Lund, J.W.; Culver, G.G.

1995-02-01

Geothermal energy is estimated to currently supply approximately 13,885 TJ/yr (13,180 x 10{sup 9} BTU/yr) of heat energy through direct heat applications in the United States. Table 1 summarizes the U.S. geothermal direct heat uses. It should be noted that Table 1 does not contain enhanced oil recovery, which was included in the 1990 update report. In the oil fields of the upper midwest (Montana, North Dakota and Wyoming), thermal waters are not being injected at higher temperatures than the oil producing zones. This means that there is no benefit to reducing oil viscosity, which would have increased production rates;more » therefore, resulting in this use being deleted from direct uses in the table. In the 1990 report two geothermal district heating systems were listed as under construction, Mammoth Lakes and Bridgeport, these systems have not been built although exploratory wells have been drilled. They are not included in the current summary of direct uses. There have been no new geothermal district heating systems started; however, San Bernardino and Klamath Falls have expanded their systems. Annual energy use of direct heat applications reported for both the 1990 and 1994 updates are shown. All of the categories experienced some increase in use, however the largest growth has been in geothermal heat pumps. From 1985 to 1990 the highest growth rate in geothermal heat pumps occurred, then tapered off some from 1990 to 1994. In the other five categories there has been a steady growth with the largest occurring in space heating, greenhouses and industrial plants. Greenhouse development has been significant in New Mexico and Utah and a new onion and garlic dehydration plant was built in Nevada.« less

Analysis of Low-Temperature Utilization of Geothermal Resources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, Brian

Full realization of the potential of what might be considered “low-grade” geothermal resources will require that we examine many more uses for the heat than traditional electricity generation. To demonstrate that geothermal energy truly has the potential to be a national energy source we will be designing, assessing, and evaluating innovative uses for geothermal-produced water such as hybrid biomass-geothermal cogeneration of electricity and district heating and efficiency improvements to the use of cellulosic biomass in addition to utilization of geothermal in district heating for community redevelopment projects. The objectives of this project were: 1) to perform a techno-economic analysis ofmore » the integration and utilization potential of low-temperature geothermal sources. Innovative uses of low-enthalpy geothermal water were designed and examined for their ability to offset fossil fuels and decrease CO2 emissions. 2) To perform process optimizations and economic analyses of processes that can utilize low-temperature geothermal fluids. These processes included electricity generation using biomass and district heating systems. 3) To scale up and generalize the results of three case study locations to develop a regionalized model of the utilization of low-temperature geothermal resources. A national-level, GIS-based, low-temperature geothermal resource supply model was developed and used to develop a series of national supply curves. We performed an in-depth analysis of the low-temperature geothermal resources that dominate the eastern half of the United States. The final products of this study include 17 publications, an updated version of the cost estimation software GEOPHIRES, and direct-use supply curves for low-temperature utilization of geothermal resources. The supply curves for direct use geothermal include utilization from known hydrothermal, undiscovered hydrothermal, and near-hydrothermal EGS resources and presented these results at the Stanford Geothermal Workshop. We also have incorporated our wellbore model into TOUGH2-EGS and began coding TOUGH2-EGS with the wellbore model into GEOPHIRES as a reservoir thermal drawdown option. Additionally, case studies for the WVU and Cornell campuses were performed to assess the potential for district heating and cooling at these two eastern U.S. sites.« less

Geothermal direct-heat utilization assistance. Quarterly report, January - March 1997

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lienau, P.

1997-04-01

This report summarizes geothermal technical assistance, R&D and technology transfer activities of the Geo-Heat Center at Oregon Institute of Technology for the second quarter of FY-97. It describes 176 contacts with parties during this period related to technical assistance with geothermal direct heat projects. Areas dealt with include geothermal heat pumps, space heating, greenhouses, aquaculture, equipment, economics and resources. Research activities are summarized on well pumping in commercial groundwater heat pump systems. A memorandum of understanding between the GHC and EIA is described. Work accomplishments on the Guidebook are discussed. Outreach activities include the publication of a geothermal direct usemore » Bulletin, dissemination of information, geothermal library, technical papers and seminars, and progress monitor reports on geothermal resources and utilization.« less

Electrical initiation of an energetic nanolaminate film

DOEpatents

Tringe, Joseph W.; Gash, Alexander E.; Barbee, Jr., Troy W.

2010-03-30

A heating apparatus comprising an energetic nanolaminate film that produces heat when initiated, a power source that provides an electric current, and a control that initiates the energetic nanolaminate film by directing the electric current to the energetic nanolaminate film and joule heating the energetic nanolaminate film to an initiation temperature. Also a method of heating comprising providing an energetic nanolaminate film that produces heat when initiated, and initiating the energetic nanolaminate film by directing an electric current to the energetic nanolaminate film and joule heating the energetic nanolaminate film to an initiation temperature.

Stress induction of Bm1 RNA in silkworm larvae: SINEs, an unusual class of stress genes

PubMed Central

Kimura, Richard H.; Choudary, Prabhakara V.; Stone, Koni K.; Schmid, Carl W.

2001-01-01

This study surveys the induction of RNA polymerase III (Pol III)–directed expression of short interspersed element (SINE) transcripts by various stresses in an animal model, silkworm larvae. Sublethal heat shock and exposure to several toxic compounds increase the level of Bm1 RNA, the silkworm SINE transcript, while also transiently increasing expression of a well-characterized stress-induced transcript, Hsp70 messenger RNA (mRNA). In certain cases, the Bm1 RNA response coincides with that of Hsp70 mRNA, but more often Bm1 RNA responds later in recovery. Baculovirus infection and exposure to certain toxic compounds increase Bm1 RNA but not Hsp70 mRNA, showing that SINE induction is not necessarily coupled to transcription of this particular heat shock gene. SINEs behave as an additional class of stress-inducible genes in living animals but are unusual as stress genes because of their high copy number, genomic dispersion, and Pol III–directed transcription. PMID:11599568

Systems efficiency and specific mass estimates for direct and indirect solar-pumped closed-cycle high-energy lasers in space

NASA Technical Reports Server (NTRS)

Monson, D. J.

1978-01-01

Based on expected advances in technology, the maximum system efficiency and minimum specific mass have been calculated for closed-cycle CO and CO2 electric-discharge lasers (EDL's) and a direct solar-pumped laser in space. The efficiency calculations take into account losses from excitation gas heating, ducting frictional and turning losses, and the compressor efficiency. The mass calculations include the power source, radiator, compressor, fluids, ducting, laser channel, optics, and heat exchanger for all of the systems; and in addition the power conditioner for the EDL's and a focusing mirror for the solar-pumped laser. The results show the major component masses in each system, show which is the lightest system, and provide the necessary criteria for solar-pumped lasers to be lighter than the EDL's. Finally, the masses are compared with results from other studies for a closed-cycle CO2 gasdynamic laser (GDL) and the proposed microwave satellite solar power station (SSPS).

Thermal rectification in thin films driven by gradient grain microstructure

NASA Astrophysics Data System (ADS)

Cheng, Zhe; Foley, Brian M.; Bougher, Thomas; Yates, Luke; Cola, Baratunde A.; Graham, Samuel

2018-03-01

As one of the basic components of phononics, thermal rectifiers transmit heat current asymmetrically similar to electronic rectifiers in microelectronics. Heat can be conducted through them easily in one direction while being blocked in the other direction. In this work, we report a thermal rectifier that is driven by the gradient grain structure and the inherent gradient in thermal properties as found in these materials. To demonstrate their thermal rectification properties, we build a spectral thermal conductivity model with complete phonon dispersion relationships using the thermophysical properties of chemical vapor deposited (CVD) diamond films which possess gradient grain microstructures. To explain the observed significant thermal rectification, the temperature and thermal conductivity distribution are studied. Additionally, the effects of temperature bias and film thickness are discussed, which shed light on tuning the thermal rectification based on the gradient microstructures. Our results show that the columnar grain microstructure makes CVD materials unique candidates for mesoscale thermal rectifiers without a sharp temperature change.

Effect of heat input on dissimilar welds of ultra high strength steel and duplex stainless steel: Microstructural and compositional analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tasalloti, H., E-mail: hamed.tasalloti.kashani@stu

The effect of heat input on the microstructure and compositional heterogeneity of welds of direct-quenched ultra high strength steel (Optim 960 QC) and duplex stainless steel (UNS S32205) was studied. The dissimilar welds were made using GMAW with a fully austenitic filler wire. In addition to grain coarsening in the heat affected zone (HAZ) of the ferritic side, it was found that an increase in heat input correlatively increased the proportional volume of bainitic to martensitic phases. Coarse ferritic grains were observed in the duplex HAZ. Higher heat input, however, had a beneficial effect on the nucleation of austenite inmore » the HAZ. Heat input had a regulatory effect on grain growth within the austenitic weld and more favorable equiaxed austenite was obtained with higher heat input. On the ferritic side of the welds, macrosegregation in the form of a martensitic intermediate zone was observed for all the cooling rates studied. However, on the duplex side, macrosegregation in the fusion boundary was only noticed with higher cooling rates. Microstructural observations and compositional analysis suggest that higher heat input could be beneficial for the structural integrity of the weld despite higher heat input increasing the extent of adverse coarse grains in the HAZ, especially on the ferritic side. - Highlights: •The effect of heat input on dissimilar welds of UHSS and DSS was studied. •Transmutation of the microstructure was discussed in detail. •The influence of heat input on compositional heterogeneity of welds was described. •Higher heat input enhanced bainitic transformation on the ferritic side. •Macrosegregation was affected by the amount of heat input on the DSS side.« less

Investigating the sensitivity of hurricane intensity and trajectory to sea surface temperatures using the regional model WRF

NASA Astrophysics Data System (ADS)

Kilic, Cevahir; Raible, Christoph C.

2015-04-01

It is well known that the sea surface temperature (SST) has an influence on the development and intensification of tropical cyclones (TCs). This influence has become even more important during the past decades, as TCs show an intensification, which goes along with an increase in SSTs. The influence of sea surface temperature (SST) anomalies on the hurricane characteristics are investigated in a set of sensitivity experiments employing the Weather Research and Forecasting (WRF) model. The idealised experiments are performed for the case of Hurricane Katrina in 2005. (Kilic and Raible, 2013) The first set of sensitivity experiments with basin-wide changes of the SST magnitude shows that the intensity goes along with changes in the SST, i.e., an increase in SST leads to an intensification of Katrina. Additionally, the trajectory is shifted to the west (east), with increasing (decreasing) SSTs. The main reason is a strengthening of the background flow. To gain further insights in the dynamics, the potential vorticity (PV) and its tendency (PVT) are analysed. A positive PVT is located to the moving direction relative to the TC centre. Splitting the PVT in the horizontal advection, vertical advection, and diabatic heating terms, we find that mainly the horizontal advection term contributes to this PVT maximum, due to a steering by strong environmental flow. The impact of the diabatic heating is of minor importance and, hence, the TC motion is dominated by horizontal advection. The amount of the horizontal advection as well as the amount of the diabatic heating rise with increasing SST due to the enhanced Carnot cycle. The second set of experiments investigates the influence of Loop Current eddies idealised by localised SST anomalies. The intensity of Hurricane Katrina is enhanced with increasing SSTs close to the core of a TC. Negative nearby SST anomalies reduce the intensity. The trajectory only changes if positive SST anomalies are located west or north of the hurricane centre. In this case the hurricane is attracted by the SST anomaly which causes an additional moisture source and increased vertical winds. This study confirm the linear relation between SST and TC intensity. However, in case of localised SST anomalies, the relative location to the TC core determes the gradient of the linear relation. The gradient decreases with increasing distance between SST anomaly and initialisation point. The anomalies located west and north of the initialisation point have a stronger impact than the ones located south and east, as they lie in the moving direction of the TC. Further, in terms of magnitude and pattern, the horizontal advection term of PVT does not strongly differ from the reference simulation. However, the pattern of diabatic heating term differs: A maximum of diabatic heating is still located in moving direction, but additionally the diabatic heating is found in the spiral rain bands. Thus, the vortex is drifted to the SST anomaly due to the asymmetry in the TC circulation induced by the diabatic heating term of the PVT. References Kilic, C., and C. C. Raible, Investigating the sensitivity of hurricane intensity and trajectory to sea surface temperatures using the regional model WRF, METEOROLOGISCHE ZEITSCHRIFT, 22(6), 685-698, 2013.

Unidirectional spin-wave heat conveyer.

PubMed

An, T; Vasyuchka, V I; Uchida, K; Chumak, A V; Yamaguchi, K; Harii, K; Ohe, J; Jungfleisch, M B; Kajiwara, Y; Adachi, H; Hillebrands, B; Maekawa, S; Saitoh, E

2013-06-01

When energy is introduced into a region of matter, it heats up and the local temperature increases. This energy spontaneously diffuses away from the heated region. In general, heat should flow from warmer to cooler regions and it is not possible to externally change the direction of heat conduction. Here we show a magnetically controllable heat flow caused by a spin-wave current. The direction of the flow can be switched by applying a magnetic field. When microwave energy is applied to a region of ferrimagnetic Y3Fe5O12, an end of the magnet far from this region is found to be heated in a controlled manner and a negative temperature gradient towards it is formed. This is due to unidirectional energy transfer by the excitation of spin-wave modes without time-reversal symmetry and to the conversion of spin waves into heat. When a Y3Fe5O12 film with low damping coefficients is used, spin waves are observed to emit heat at the sample end up to 10 mm away from the excitation source. The magnetically controlled remote heating we observe is directly applicable to the fabrication of a heat-flow controller.

Technology of High-speed Direct Laser Deposition from Ni-based Superalloys

NASA Astrophysics Data System (ADS)

Klimova-Korsmik, Olga; Turichin, Gleb; Zemlyakov, Evgeniy; Babkin, Konstantin; Petrovsky, Pavel; Travyanov, Andrey

Recently, additive manufacturing is the one of most perspective technologies; it can replace conventional methods of casting and subsequent time-consuming machining. One of the most interesting additive technologies - high-speed direct laser deposition (HSDLD) allows realizing heterophase process during the manufacturing, which there is process takes place with a partial melting of powder. This is particularly important for materials, which are sensitive to strong fluctuations of temperature treatment regimes, like nickel base alloys with high content of gamma prime phase. This alloys are interested for many industrial areas, mostly there are used in engine systems, aircraft and shipbuilding, aeronautics. Heating and cooling rates during the producing process determine structure and affect on its properties. Using HSDLD process it possible to make a products from Ni superalloys with ultrafine microstructure and satisfactory mechanical characteristics without special subsequent heatreatment.

Metal Additive Manufacturing: A Review of Mechanical Properties

NASA Astrophysics Data System (ADS)

Lewandowski, John J.; Seifi, Mohsen

2016-07-01

This article reviews published data on the mechanical properties of additively manufactured metallic materials. The additive manufacturing techniques utilized to generate samples covered in this review include powder bed fusion (e.g., EBM, SLM, DMLS) and directed energy deposition (e.g., LENS, EBF3). Although only a limited number of metallic alloy systems are currently available for additive manufacturing (e.g., Ti-6Al-4V, TiAl, stainless steel, Inconel 625/718, and Al-Si-10Mg), the bulk of the published mechanical properties information has been generated on Ti-6Al-4V. However, summary tables for published mechanical properties and/or key figures are included for each of the alloys listed above, grouped by the additive technique used to generate the data. Published values for mechanical properties obtained from hardness, tension/compression, fracture toughness, fatigue crack growth, and high cycle fatigue are included for as-built, heat-treated, and/or HIP conditions, when available. The effects of test orientation/build direction on properties, when available, are also provided, along with discussion of the potential source(s) (e.g., texture, microstructure changes, defects) of anisotropy in properties. Recommendations for additional work are also provided.

The development of a performance-enhancing additive for vapor-compression heat pumps

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grzyll, L.R.; Scaringe, R.P.; Gottschlich, J.M.

1997-12-31

This paper describes the testing results of a vapor-compression heat pump operating with HFC-134a refrigerant and a performance-enhancing additive. Preliminary bench-top testing of this additive, when added to polyolester (POE) lubricant and HFC-134a refrigerant, showed surprising enhancements to system COP. To further investigate this finding, the authors designed and fabricated a vapor-compression heat pump test stand for the 3--5 ton range. The authors investigated the effect of different concentrations of this additive on various system performance parameters such as cooling capacity, compressor power requirement, pressure ratio, compressor pressure difference, compressor isentropic efficiency, refrigerant flow rate, and heat exchanger performance. Themore » authors investigated various heat source and heat sink conditions to simulate air-conditioning and heat pump operating conditions. To investigate the effect of this additive on compressor lubrication and life, the authors performed compressor life tests (with scroll and reciprocating compressors), and had lubrication wear tests performed with various concentrations of the additive in the POE lubricant.« less

Structural Assembly for Cold Plate Cooling

NASA Technical Reports Server (NTRS)

Zaffetti, Mark A. (Inventor); Taddey, Edmund P. (Inventor)

2014-01-01

A device including a structural member having a heat spreader and an electronic device mounted directly to a first surface of the heat spreader of the structural member. The device also includes a cold plate mounted directly to the first surface of the heat spreader of the structural member.

Microgravity

NASA Image and Video Library

1997-11-15

The Isothermal Dendritic Growth Experiment (IDGE), flown on three Space Shuttle missions, is yielding new insights into virtually all industrially relevant metal and alloy forming operations. IDGE used transparent organic liquids that form dendrites (treelike structures) similar to those inside metal alloys. Comparing Earth-based and space-based dendrite growth velocity, tip size and shape provides a better understanding of the fundamentals of dentritic growth, including gravity's effects. Shalowgraphic images of pivalic acid (PVA) dendrites forming from the melt show the subtle but distinct effects of gravity-driven heat convection on dentritic growth. In orbit, the dendrite grows as its latent heat is liberated by heat conduction. This yields a blunt dendrite tip. On Earth, heat is carried away by both conduction and gravity-driven convection. This yields a sharper dendrite tip. In addition, under terrestrial conditions, the sidebranches growing in the direction of gravity are augmented as gravity helps carry heat out of the way of the growing sidebranches as opposed to microgravity conditions where no augmentation takes place. IDGE was developed by Rensselaer Polytechnic Institute and NASA/Glenn Research Center. Advanced follow-on experiments are being developed for flight on the International Space Station. Photo Credit: NASA/Glenn Research Center

Experimental Study of Vane Heat Transfer and Film Cooling at Elevated Levels of Turbulence

NASA Technical Reports Server (NTRS)

Ames, Forrest E.

1996-01-01

This report documents the results of an experimental study on the influence of high level turbulence on vane film cooling and the influence of film cooling on vane heat transfer. Three different cooling configurations were investigated which included one row of film cooling on both pressure and suction surfaces, two staggered rows of film cooling on both suction and pressure surfaces, and a shower-head cooling array. The turbulence had a strong influence on film cooling effectiveness, particularly on the pressure surface where local turbulence levels were the highest. For the single row of holes, the spanwise mixing quickly reduced centerline effectiveness levels while mixing in the normal direction was more gradual. The film cooling had a strong influence on the heat transfer in the laminar regions of the vane. The effect of film cooling on heat transfer was noticeable in the turbulent regions but augmentation ratios were significantly lower. In addition to heat transfer and film cooling, velocity profiles were taken downstream of the film cooling rows at three spanwise locations. These profile comparisons documented the strong spanwise mixing due to the high turbulence. Total pressure exit measurements were also documented for the three configurations.

Thermoreflectance microscopy measurements of the Joule heating characteristics of high- Tc superconducting terahertz emitters

NASA Astrophysics Data System (ADS)

Kashiwagi, Takanari; Tanaka, Taiga; Watanabe, Chiharu; Kubo, Hiroyuki; Komori, Yuki; Yuasa, Takumi; Tanabe, Yuki; Ota, Ryusei; Kuwano, Genki; Nakamura, Kento; Tsujimoto, Manabu; Minami, Hidetoshi; Yamamoto, Takashi; Klemm, Richard A.; Kadowaki, Kazuo

2017-12-01

Joule heating is the central issue in order to develop high-power and high-performance terahertz (THz) emission from mesa devices employing the intrinsic Josephson junctions in a layered high transition-temperature Tc superconductor. Here, we describe a convenient local thermal measurement technique using charge-coupled-device-based thermoreflectance microscopy, with the highest spatial resolution to date. This technique clearly proves that the relative temperature changes of the mesa devices between different bias points on the current-voltage characteristics can be measured very sensitively. In addition, the heating characteristics on the surface of the mesa devices can be detected more directly without any special treatment of the mesa surface such as previous coatings with SiC micro-powders. The results shown here clearly indicate that the contact resistance strongly affects the formation of an inhomogeneous temperature distribution on the mesa structures. Since the temperature and sample dependencies of the Joule heating characteristics can be measured quickly, this simple thermal evaluation technique is a useful tool to check the quality of the electrical contacts, electrical wiring, and sample defects. Thus, this technique could help to reduce the heating problems and to improve the performance of superconducting THz emitter devices.

Poleward upgliding Siberian atmospheric rivers over sea ice heat up Arctic upper air.

PubMed

Komatsu, Kensuke K; Alexeev, Vladimir A; Repina, Irina A; Tachibana, Yoshihiro

2018-02-13

We carried out upper air measurements with radiosondes during the summer over the Arctic Ocean from an icebreaker moving poleward from an ice-free region, through the ice edge, and into a region of thick ice. Rapid warming of the Arctic is a significant environmental issue that occurs not only at the surface but also throughout the troposphere. In addition to the widely accepted mechanisms responsible for the increase of tropospheric warming during the summer over the Arctic, we showed a new potential contributing process to the increase, based on our direct observations and supporting numerical simulations and statistical analyses using a long-term reanalysis dataset. We refer to this new process as "Siberian Atmospheric Rivers (SARs)". Poleward upglides of SARs over cold air domes overlying sea ice provide the upper atmosphere with extra heat via condensation of water vapour. This heating drives increased buoyancy and further strengthens the ascent and heating of the mid-troposphere. This process requires the combination of SARs and sea ice as a land-ocean-atmosphere system, the implication being that large-scale heat and moisture transport from the lower latitudes can remotely amplify the warming of the Arctic troposphere in the summer.

Role of curcumin in the conversion of asparagine into acrylamide during heating.

PubMed

Hamzalıoğlu, Aytül; Mogol, Burçe A; Lumaga, Roberta Barone; Fogliano, Vincenzo; Gökmen, Vural

2013-06-01

This study aimed to investigate the ability of curcumin to convert asparagine into acrylamide during heating at different temperatures. Binary and ternary model systems of asparagine-curcumin and asparagine-curcumin-fructose were used to determine the role of curcumin on acrylamide formation in competitive and uncompetitive reaction conditions. The results indicated that curcumin could potentially contribute to acrylamide formation under long-term heating conditions as long as asparagine was present in the medium. The amount of acrylamide formed in the ternary system was slightly higher than in the binary system during heating (p < 0.05), because of the higher concentrations of carbonyl compounds initially available. The kinetic trends were similar in both model systems evidencing that fructose reacted with asparagine more rapidly than curcumin. The data reveal that acrylamide formation in the temperature range of 150-200°C obeys Arrhenius law with activation energy of 79.1 kJ/mole. Data of this work showed the possibility that antioxidants having a carbonyl compound can react directly with ASN leading to acrylamide. The addition of antioxidants to foods may increase the formation of acrylamide upon long-term heating if free sugar concentration is low and ASN concentration is relatively high.

Simulated heat waves affected alpine grassland only in combination with drought.

PubMed

De Boeck, Hans J; Bassin, Seraina; Verlinden, Maya; Zeiter, Michaela; Hiltbrunner, Erika

2016-01-01

The Alpine region is warming fast, and concurrently, the frequency and intensity of climate extremes are increasing. It is currently unclear whether alpine ecosystems are sensitive or resistant to such extremes. We subjected Swiss alpine grassland communities to heat waves with varying intensity by transplanting monoliths to four different elevations (2440-660 m above sea level) for 17 d. Half of these were regularly irrigated while the other half were deprived of irrigation to additionally induce a drought at each site. Heat waves had no significant impacts on fluorescence (Fv /Fm , a stress indicator), senescence and aboveground productivity if irrigation was provided. However, when heat waves coincided with drought, the plants showed clear signs of stress, resulting in vegetation browning and reduced phytomass production. This likely resulted from direct drought effects, but also, as measurements of stomatal conductance and canopy temperatures suggest, from increased high-temperature stress as water scarcity decreased heat mitigation through transpiration. The immediate responses to heat waves (with or without droughts) recorded in these alpine grasslands were similar to those observed in the more extensively studied grasslands from temperate climates. Responses following climate extremes may differ in alpine environments, however, because the short growing season likely constrains recovery. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

Midterm Summary of Japan-US Fusion Cooperation Program TITAN

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muroga, Takeo; Sze, Dai-Kai; Sokolov, Mikhail

2011-01-01

Japan-US cooperation program TITAN (Tritium, Irradiation and Thermofluid for America and Nippon) started in April 2007 as 6-year project. This is the summary report at the midterm of the project. Historical overview of the Japan-US cooperation programs and direction of the TITAN project in its second half are presented in addition to the technical highlights. Blankets are component systems whose principal functions are extraction of heat and tritium. Thus it is crucial to clarify the potentiality for controlling heat and tritium flow throughout the first wall, blanket and out-of-vessel recovery systems. The TITAN project continues the JUPITER-II activity but extendsmore » its scope including the first wall and the recovery systems with the title of 'Tritium and thermofluid control for magnetic and inertial confinement systems'. The objective of the program is to clarify the mechanisms of tritium and heat transfer throughout the first-wall, the blanket and the heat/tritium recovery systems under specific conditions to fusion such as irradiation, high heat flux, circulation and high magnetic fields. Based on integrated models, the breeding, transfer, inventory of tritium and heat extraction properties will be evaluated for some representative liquid breeder blankets and the necessary database will be obtained for focused research in the future.« less

Exploration of High Harmonic Fast Wave Heating on the National Spherical Torus Experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

J.R. Wilson; R.E. Bell; S. Bernabei

2003-02-11

High Harmonic Fast Wave (HHFW) heating has been proposed as a particularly attractive means for plasma heating and current drive in the high-beta plasmas that are achievable in spherical torus (ST) devices. The National Spherical Torus Experiment (NSTX) [Ono, M., Kaye, S.M., Neumeyer, S., et al., Proceedings, 18th IEEE/NPSS Symposium on Fusion Engineering, Albuquerque, 1999, (IEEE, Piscataway, NJ (1999), p. 53.)] is such a device. An radio-frequency (rf) heating system has been installed on NSTX to explore the physics of HHFW heating, current drive via rf waves and for use as a tool to demonstrate the attractiveness of the STmore » concept as a fusion device. To date, experiments have demonstrated many of the theoretical predictions for HHFW. In particular, strong wave absorption on electrons over a wide range of plasma parameters and wave parallel phase velocities, wave acceleration of energetic ions, and indications of current drive for directed wave spectra have been observed. In addition HHFW heating has been used to explore the energy transport properties of NSTX plasmas, to create H-mode (high-confinement mode) discharges with a large fraction of bootstrap current and to control the plasma current profile during the early stages of the discharge.« less

A simple differential steady-state method to measure the thermal conductivity of solid bulk materials with high accuracy.

PubMed

Kraemer, D; Chen, G

2014-02-01

Accurate measurements of thermal conductivity are of great importance for materials research and development. Steady-state methods determine thermal conductivity directly from the proportionality between heat flow and an applied temperature difference (Fourier Law). Although theoretically simple, in practice, achieving high accuracies with steady-state methods is challenging and requires rather complex experimental setups due to temperature sensor uncertainties and parasitic heat loss. We developed a simple differential steady-state method in which the sample is mounted between an electric heater and a temperature-controlled heat sink. Our method calibrates for parasitic heat losses from the electric heater during the measurement by maintaining a constant heater temperature close to the environmental temperature while varying the heat sink temperature. This enables a large signal-to-noise ratio which permits accurate measurements of samples with small thermal conductance values without an additional heater calibration measurement or sophisticated heater guards to eliminate parasitic heater losses. Additionally, the differential nature of the method largely eliminates the uncertainties of the temperature sensors, permitting measurements with small temperature differences, which is advantageous for samples with high thermal conductance values and/or with strongly temperature-dependent thermal conductivities. In order to accelerate measurements of more than one sample, the proposed method allows for measuring several samples consecutively at each temperature measurement point without adding significant error. We demonstrate the method by performing thermal conductivity measurements on commercial bulk thermoelectric Bi2Te3 samples in the temperature range of 30-150 °C with an error below 3%.

Compact Directional Microwave Antenna for Localized Heating

NASA Technical Reports Server (NTRS)

Fink, Patrick W.; Lin, Gregory Y.; Chu, Andrew W.; Dobbins, Justin A.; Arndt, G. Dickey; Ngo, Phong

2008-01-01

A directional, catheter-sized cylindrical antenna has been developed for localized delivery of microwave radiation for heating (and thus killing) diseased tissue without excessively heating nearby healthy tissue. By "localized" is meant that the antenna radiates much more in a selected azimuthal direction than in the opposite radial direction, so that it heats tissue much more on one side than it does on the opposite side. This antenna can be inserted using either a catheter or a syringe. A 2.4-mm prototype was tested, although smaller antennas are possible. Prior compact, cylindrical antennas designed for therapeutic localized hyperthermia do not exhibit such directionality; that is, they radiate in approximately axisymmetric patterns. Prior directional antennas designed for the same purpose have been, variously, (1) too large to fit within catheters or (2) too large, after deployment from catheters, to fit within the confines of most human organs. In contrast, the present antenna offers a high degree of directionality and is compact enough to be useable as a catheter in some applications.

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

This report summarizes geothermal technical assistance, R&D, and technology transfer activities of the Geo-Heat Center. It describes 95 contacts with parties during this period related to technical assistance with goethermal direct heat projects. Areas dealt with include geothermal heat pumps, space heating, greenhouses, aquaculture, equipment, economics, and resources. Research activities are summarized on geothermal district heating system cost evaluation and silica waste utilization project. Outreach activities include publication of a geothermal direct use Bulletin, dissemination of information, goethermal library, technical papers and seminars, and progress monitor reports on geothermal resources and utilization.

Method for welding an article and terminating the weldment within the perimeter of the article

NASA Technical Reports Server (NTRS)

Snyder, John H. (Inventor); Smashey, Russell W. (Inventor); Boerger, Eric J. (Inventor); Borne, Bruce L. (Inventor)

2000-01-01

An article is welded, as in weld repair of a defect, by positioning a weld lift-off block at a location on the surface of the article adjacent to the intended location of the end of the weldment on the surface of the article. The weld lift-off block has a wedge shape including a base contacting the surface of the article, and an upper face angled upwardly from the base from a base leading edge. A weld pool is formed on the surface of the article by directly heating the surface of the article using a heat source. The heat source is moved relative to the surface of the article and onto the upper surface of the weld lift-off block by crossing the leading edge of the wedge, without discontinuing the direct heating of the article by the heat source. The heating of the article with the heat source is discontinued only after the heat source is directly heating the upper face of the weld lift-off block, and not the article.

Milestone Report #2: Direct Evaporator Leak and Flammability Analysis Modifications and Optimization of the Organic Rankine Cycle to Improve the Recovery of Waste Heat

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guillen, Donna Post

2013-09-01

The direct evaporator is a simplified heat exchange system for an Organic Rankine Cycle (ORC) that generates electricity from a gas turbine exhaust stream. Typically, the heat of the exhaust stream is transferred indirectly to the ORC by means of an intermediate thermal oil loop. In this project, the goal is to design a direct evaporator where the working fluid is evaporated in the exhaust gas heat exchanger. By eliminating one of the heat exchangers and the intermediate oil loop, the overall ORC system cost can be reduced by approximately 15%. However, placing a heat exchanger operating with a flammablemore » hydrocarbon working fluid directly in the hot exhaust gas stream presents potential safety risks. The purpose of the analyses presented in this report is to assess the flammability of the selected working fluid in the hot exhaust gas stream stemming from a potential leak in the evaporator. Ignition delay time for cyclopentane at temperatures and pressure corresponding to direct evaporator operation was obtained for several equivalence ratios. Results of a computational fluid dynamic analysis of a pinhole leak scenario are given.« less

Feasibility of using interstitial ultrasound for intradiscal thermal therapy: a study in human cadaver lumbar discs

NASA Astrophysics Data System (ADS)

Nau, William H.; Diederich, Chris J.; Shu, Richard

2005-06-01

Application of heat in the spine using resistive wire heating devices is currently being used clinically for minimally invasive treatment of discogenic low back pain. In this study, interstitial ultrasound was evaluated for the potential to heat intradiscal tissue more precisely by directing energy towards the posterior annular wall while avoiding vertebral bodies. Two single-element directional applicator design configurations were tested: a 1.5 mm OD direct-coupled (DC) applicator which can be implanted directly within the disc, and a catheter-cooled (CC) applicator which is inserted in a 2.4 mm OD catheter with integrated water cooling and implanted within the disc. The transducers were sectored to produce 90° spatial heating patterns for directional control. Both applicator configurations were evaluated in four human cadaver lumbar disc motion segments. Two heating protocols were employed in this study in which the temperature measured 5 mm away from the applicator was controlled to either T = 52 °C, or T > 70 °C for the treatment period. These temperatures (thermal doses) are representative of those required for thermal necrosis of in-growing nociceptor nerve fibres and disc cellularity alone, or with coagulation and restructuring of annular collagen in the high-temperature case. Steady-state temperature maps, and thermal doses (t43) were used to assess the thermal treatments. Results from these studies demonstrated the capability of controlling temperature distributions within selected regions of the disc and annular wall using interstitial ultrasound, with minimal vertebral end-plate heating. While directional heating was demonstrated with both applicator designs, the CC configuration had greater directional heating capabilities and offered better temperature control than the DC configuration, particularly during the high-temperature protocol. Further, ultrasound energy was capable of penetrating within the highly attenuating disc tissue to produce more extensive radial thermal penetration, lower maximum intradiscal temperature, and shorter treatment times than can be achieved with current clinical intradiscal heating technology. Thus, interstitial ultrasound offers potential as a more precise and faster heating modality for the clinical management of low back pain.

Characterization of Centrifugally-Loaded Flame Migration for Ultra-Compact Combustors

DTIC Science & Technology

2011-10-01

11 T04 combustor exit temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Q b combustor heat addition...11 Q ab afterburner heat addition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11...the mass flow rates, with heat addition, lead to reaching a specific g-load. In addition to varying g-load, a larger scale UCC will require a

The effects of climate change on heating energy consumption of office buildings in different climate zones in China

NASA Astrophysics Data System (ADS)

Meng, Fanchao; Li, Mingcai; Cao, Jingfu; Li, Ji; Xiong, Mingming; Feng, Xiaomei; Ren, Guoyu

2017-06-01

Climate plays an important role in heating energy consumption owing to the direct relationship between space heating and changes in meteorological conditions. To quantify the impact, the Transient System Simulation Program software was used to simulate the heating loads of office buildings in Harbin, Tianjin, and Shanghai, representing three major climate zones (i.e., severe cold, cold, and hot summer and cold winter climate zones) in China during 1961-2010. Stepwise multiple linear regression was performed to determine the key climatic parameters influencing heating energy consumption. The results showed that dry bulb temperature (DBT) is the dominant climatic parameter affecting building heating loads in all three climate zones across China during the heating period at daily, monthly, and yearly scales (R 2 ≥ 0.86). With the continuous warming climate in winter over the past 50 years, heating loads decreased by 14.2, 7.2, and 7.1 W/m2 in Harbin, Tianjin, and Shanghai, respectively, indicating that the decreasing rate is more apparent in severe cold climate zone. When the DBT increases by 1 °C, the heating loads decrease by 253.1 W/m2 in Harbin, 177.2 W/m2 in Tianjin, and 126.4 W/m2 in Shanghai. These results suggest that the heating energy consumption can be well predicted by the regression models at different temporal scales in different climate conditions owing to the high determination coefficients. In addition, a greater decrease in heating energy consumption in northern severe cold and cold climate zones may efficiently promote the energy saving in these areas with high energy consumption for heating. Particularly, the likely future increase in temperatures should be considered in improving building energy efficiency.

Protection of mice from oral Candidiasis by heat-killed enterococcus faecalis, possibly through its direct binding to Candida albicans.

PubMed

Ishijima, Sanae A; Hayama, Kazumi; Ninomiya, Kentaro; Iwasa, Masahiro; Yamazaki, Masatoshi; Abe, Shigeru

2014-01-01

To develop a new therapy against oral candidiasis, a commensal microorganism, Enterococcus faecalis was tested for its ability to modulate Candida growth in vitro and its therapeutic activities against a murine model in vivo. Addition of heat-killed E. faecalis strain EF2001 (EF2001) isolated from healthy human feces to the culture of C. albicans strain TIMM1768 inhibited adherence of the latter to a microtiter plate in a dose dependent manner and Candida cells surrounded by EF2001 were increased. To examine the protective activities of EF2001 in vivo, heat-killed EF2001 was applied orally before and after inoculation of Candida to the tongue of mice previously immunosuppressed. Two days after inoculation this inoculation, both the symptom score and CFU from swabbed-tongue were significantly reduced in the EF2001-treated animals. Histological analysis indicated that EF2001 may potentiate the accumulation of polymorphnuclear cells near a Candida-infected region. These results suggest that oral administration of EF2001 has protective activity against oral candidiasis and that the in vivo activity may be reflected by direct interaction between EF2001 and Candida cells in vitro and the potentiation of an immunostimulatory effect of EF2001.

Investigation of transition from thermal- to solutal-Marangoni flow in dilute alcohol/water mixtures using nano-plasmonic heaters

NASA Astrophysics Data System (ADS)

Namura, Kyoko; Nakajima, Kaoru; Suzuki, Motofumi

2018-02-01

We experimentally investigated Marangoni flows around a microbubble in diluted 1-butanol/water, 2-propanol/water, and ethanol/water mixtures using the thermoplasmonic effect of gold nanoisland film. A laser spot on the gold nanoisland film acted as a highly localized heat source that was utilized to generate stable air microbubbles with diameters of 32-48 μm in the fluid and to induce a steep temperature gradient on the bubble surface. The locally heated bubble has a flow along the bubble surface, with the flow direction showing a clear transition depending on the alcohol concentrations. The fluid is driven from the hot to cold regions when the alcohol concentration is lower than the transition concentration, whereas it is driven from the cold to hot regions when the concentration is higher than the transition concentration. In addition, the transition concentration increases as the carbon number of the alcohol decreases. The observed flow direction transition is explained by the balance of the thermal- and solutal-Marangoni forces that are cancelled out for the transition concentration. The selective evaporation of the alcohol at the locally heated surface allows us to generate stable and rapid thermoplasmonic solutal-Marangoni flows in the alcohol/water mixtures.

Thermally Simulated Testing of a Direct-Drive Gas-Cooled Nuclear Reactor

NASA Technical Reports Server (NTRS)

Godfroy, Thomas; Bragg-Sitton, Shannon; VanDyke, Melissa

2003-01-01

This paper describes the concept and preliminary component testing of a gas-cooled, UN-fueled, pin-type reactor which uses He/Xe gas that goes directly into a recuperated Brayton system to produce electricity for nuclear electric propulsion. This Direct-Drive Gas-Cooled Reactor (DDG) is designed to be subcritical under water or wet-sand immersion in case of a launch accident. Because the gas-cooled reactor can directly drive the Brayton turbomachinery, it is possible to configure the system such that there are no external surfaces or pressure boundaries that are refractory metal, even though the gas delivered to the turbine is 1144 K. The He/Xe gas mixture is a good heat transport medium when flowing, and a good insulator when stagnant. Judicious use of stagnant cavities as insulating regions allows transport of the 1144-K gas while keeping all external surfaces below 900 K. At this temperature super-alloys (Hastelloy or Inconel) can be used instead of refractory metals. Super-alloys reduce the technology risk because they are easier to fabricate than refractory metals, we have a much more extensive knowledge base on their characteristics, and, because they have a greater resistance to oxidation, system testing is eased. The system is also relatively simple in its design: no additional coolant pumps, heat exchanger, or freeze-thaw systems are required. Key to success of this concept is a good knowledge of the heat transfer between the fuel pins and the gas, as well as the pressure drop through the system. This paper describes preliminary testing to obtain this key information, as well as experience in demonstrating electrical thermal simulation of reactor components and concepts.

Interaction between casein micelles and whey protein/κ-casein complexes during renneting of heat-treated reconstituted skim milk powder and casein micelle/serum mixtures.

PubMed

Kethireddipalli, Prashanti; Hill, Arthur R; Dalgleish, Douglas G

2011-02-23

Casein micelles were separated from unheated reconstituted skim milk powder (RSMP) and were resuspended in the serum of RSMP that had been heated, with and without dialysis of this serum against unheated RSMP. Using size-exclusion chromatography, it was found that the soluble complexes of whey protein (WP) with κ-casein in the serum of the heated milk bind progressively to unheated casein micelles during renneting, even prior to the onset of clotting. Similar trends were noted when casein micelles from RSMP heated at pH values of 6.7, 7.1, or 6.3, each with different amounts of WP coating the micelles, were renneted in the presence of soluble WP/κ-casein complexes. No matter what was the initial load of micelle-bound WP complexes, all micelle types were capable of binding additional serum protein complexes during renneting. However, it is not clear that this binding of WP/κ-casein complexes to the micellar surface is a direct cause of the impaired rennet clotting of the RSMP.

Direct Digital Control of HVAC (Heating, Ventilating, and Air Conditioning).

DTIC Science & Technology

1985-01-01

controller func- tions such as time-of-day, economizer cycles, reset, load shedding, chiller optimization , VAV fan synchronization, and optimum start/stop...control system such as that illustrated in Fig- urc 4. Data on setpoints , reset schedules, and event timing, such as that presented in Figure 6, are...program code (Figure 7). In addition to the control logic, setpoint and other data are readily available. Program logi:, setpoint and schedule data, and

An Hybrid liquid nitrogen system to cool a large detector

NASA Astrophysics Data System (ADS)

l'Allemand, J. L. Lizon a.

2017-12-01

OmegaCAM is a wide field camera housing a mosaic of 32 CCD detectors. For the optimal trade-off between dark current, sensitivity, and cosmetics, these detectors need to be operated at a temperature of about 155 K. The detectors mosaic with a total area of 630 cm2 directly facing the Dewar entrance window, is exposed to a considerable radiation heat load. This can only be achieved with a high-performing cooling system. In addition this system has to be operated at the moving focal plane of a telescope. The paper describes the cooling system, which is build such that it makes the most efficient use of the cooling power of the liquid nitrogen. This is obtained by forcing the nitrogen through a series of well designed and strategically distributed heat exchangers. Results and performance of the system recorded during the laboratory system testing are reported as well. In addition to the cryogenic performance, the document reports also about the overall performance of the instrument including long term vacuum behavior.

Structural evaluation of a DTHR bundle divertor particle collector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prevenslik, T.V.

1980-09-01

The purpose of this report is to present a structural evaluation of the current bundle divertor particle collector BDPC design under a peak heat flux in relation to criteria that protect against coolant leakage into the plasma over replacement schedules planned during DTHR operation. In addition, an assessment of the BDPC structural integrity at higher heat fluxes is presented. Further, recommendations for modifications in the current BDPC design that would improve design reliability to be considered in future design studies are described. Finally, experimental test programs directed to establishing materials data necessary in providing greater confidence in subsequent structural evaluationsmore » of BDPC designs in relation to coolant leakage over planned replacement schedules are identified.« less

Characterization and Computational Modeling of Minor Phases in Alloy LSHR

NASA Technical Reports Server (NTRS)

Jou, Herng-Jeng; Olson, Gregory; Gabb, Timothy; Garg, Anita; Miller, Derek

2012-01-01

The minor phases of powder metallurgy disk superalloy LSHR were studied. Samples were consistently heat treated at three different temperatures for long times to approach equilibrium. Additional heat treatments were also performed for shorter times, to assess minor phase kinetics in non-equilibrium conditions. Minor phases including MC carbides, M23C6 carbides, M3B2 borides, and sigma were identified. Their average sizes and total area fractions were determined. CALPHAD thermodynamics databases and PrecipiCalc(TradeMark), a computational precipitation modeling tool, were employed with Ni-base thermodynamics and diffusion databases to model and simulate the phase microstructural evolution observed in the experiments with an objective to identify the model limitations and the directions of model enhancement.

Estimation of Surface Temperature and Heat Flux by Inverse Heat Transfer Methods Using Internal Temperatures Measured While Radiantly Heating a Carbon/Carbon Specimen up to 1920 F

NASA Technical Reports Server (NTRS)

Pizzo, Michelle; Daryabeigi, Kamran; Glass, David

2015-01-01

The ability to solve the heat conduction equation is needed when designing materials to be used on vehicles exposed to extremely high temperatures; e.g. vehicles used for atmospheric entry or hypersonic flight. When using test and flight data, computational methods such as finite difference schemes may be used to solve for both the direct heat conduction problem, i.e., solving between internal temperature measurements, and the inverse heat conduction problem, i.e., using the direct solution to march forward in space to the surface of the material to estimate both surface temperature and heat flux. The completed research first discusses the methods used in developing a computational code to solve both the direct and inverse heat transfer problems using one dimensional, centered, implicit finite volume schemes and one dimensional, centered, explicit space marching techniques. The developed code assumed the boundary conditions to be specified time varying temperatures and also considered temperature dependent thermal properties. The completed research then discusses the results of analyzing temperature data measured while radiantly heating a carbon/carbon specimen up to 1920 F. The temperature was measured using thermocouple (TC) plugs (small carbon/carbon material specimens) with four embedded TC plugs inserted into the larger carbon/carbon specimen. The purpose of analyzing the test data was to estimate the surface heat flux and temperature values from the internal temperature measurements using direct and inverse heat transfer methods, thus aiding in the thermal and structural design and analysis of high temperature vehicles.

Heat transfer Effect by soil temperature changes under shallow groundwater in the Mu Us desert, Northern China

NASA Astrophysics Data System (ADS)

Qiao, X.; Lu, R.; Donghui, C.

2015-12-01

Soil temperature change is principle elements to biological growth, soil freeze or thawing process. A situ field was conducted in the Mu Us desert of Wushen Qi County, Inner Mongolia, to mainly monitor soil temperature, moisture content and groundwater level. The unconfined aquifer constituted by Quaternary fine eolian sand, groundwater level is 125cm. This paper, choosing date from May 1, 2013 to April 30, 2014, soil day temperature is conducted by 3:00, 6:00,till 24:00, vertical spacing including 2cm,5 cm、10 cm、15 cm、20 cm, 75cm,125cm,which its symbol is T10, T15, T20, T75, T125 respectively. Here, surface layer temperature TS calculated by soil temperature of 2-5cm depth. Due to only 5 minutes interval, this state was taken as a state one. (1) soil temperature has mixture change on surface layer and its temperature different is over 35 ℃. (2) Surface layer temperature changes of every month have three stages and its conducted heat, which calculated between TS and T10. Since TS exceeds T10 and heat transfer direction is from surface to underground in May, June and July 2013, even heat transfer amounts reduced by participation in July. However, TS is inferior to T10 and conduced heat direction reverse in August till to February 2014.Continually conduced heat start to next circulation and then it's heat direction from surface to underground due to TS exceeds T10 again in March and April 2014. (3) Temperature changes of phreatic water table every month have also three stages and its conducted heat which calculated between T75 and T125, heat transfer direction from unsaturated zone to saturated zone due to T75 exceeds T125 from May till middle September 2013. However, T75 is inferior to T125 and heat direction reverse from late September 2013 till May 2014, but conduced heat direction starts to change from unsaturated zone to saturated zone again in early April 2014.The result can imply shallow gruondwater has some contribution to surface layer temperature in different seasons.

Comparison of DSMC and CFD Solutions of Fire II Including Radiative Heating

NASA Technical Reports Server (NTRS)

Liechty, Derek S.; Johnston, Christopher O.; Lewis, Mark J.

2011-01-01

The ability to compute rarefied, ionized hypersonic flows is becoming more important as missions such as Earth reentry, landing high mass payloads on Mars, and the exploration of the outer planets and their satellites are being considered. These flows may also contain significant radiative heating. To prepare for these missions, NASA is developing the capability to simulate rarefied, ionized flows and to then calculate the resulting radiative heating to the vehicle's surface. In this study, the DSMC codes DAC and DS2V are used to obtain charge-neutral ionization solutions. NASA s direct simulation Monte Carlo code DAC is currently being updated to include the ability to simulate charge-neutral ionized flows, take advantage of the recently introduced Quantum-Kinetic chemistry model, and to include electronic energy levels as an additional internal energy mode. The Fire II flight test is used in this study to assess these new capabilities. The 1634 second data point was chosen for comparisons to be made in order to include comparisons to computational fluid dynamics solutions. The Knudsen number at this point in time is such that the DSMC simulations are still tractable and the CFD computations are at the edge of what is considered valid. It is shown that there can be quite a bit of variability in the vibrational temperature inferred from DSMC solutions and that, from how radiative heating is computed, the electronic temperature is much better suited for radiative calculations. To include the radiative portion of heating, the flow-field solutions are post-processed by the non-equilibrium radiation code HARA. Acceptable agreement between CFD and DSMC flow field solutions is demonstrated and the progress of the updates to DAC, along with an appropriate radiative heating solution, are discussed. In addition, future plans to generate more high fidelity radiative heat transfer solutions are discussed.

Substrate thermal conductivity controls the ability to manufacture microstructures via laser-induced direct write

NASA Astrophysics Data System (ADS)

Tomko, John A.; Olson, David H.; Braun, Jeffrey L.; Kelliher, Andrew P.; Kaehr, Bryan; Hopkins, Patrick E.

2018-01-01

In controlling the thermal properties of the surrounding environment, we provide insight into the underlying mechanisms driving the widely used laser direct write method for additive manufacturing. We find that the onset of silver nitrate reduction for the formation of direct write structures directly corresponds to the calculated steady-state temperature rises associated with both continuous wave and high-repetition rate, ultrafast pulsed laser systems. Furthermore, varying the geometry of the heat affected zone, which is controllable based on in-plane thermal diffusion in the substrate, and laser power, allows for control of the written geometries without any prior substrate preparation. These findings allow for the advance of rapid manufacturing of micro- and nanoscale structures with minimal material constraints through consideration of the laser-controllable thermal transport in ionic liquid/substrate media.

Assessment of Global Annual Atmospheric Energy Balance from Satellite Observations

NASA Technical Reports Server (NTRS)

Lin, Bing; Stackhouse, Paul; Minnis, Patrick; Wielicki, Bruce A.; Hu, Yongxiang; Sun, Wenbo; Fan, Tai-Fang (Alice); Hinkelman, Laura

2008-01-01

Global atmospheric energy balance is one of the fundamental processes for the earth's climate system. This study uses currently available satellite data sets of radiative energy at the top of atmosphere (TOA) and surface and latent and sensible heat over oceans for the year 2000 to assess the global annual energy budget. Over land, surface radiation data are used to constrain assimilated results and to force the radiation, turbulent heat, and heat storage into balance due to a lack of observation-based turbulent heat flux estimations. Global annual means of the TOA net radiation obtained from both direct measurements and calculations are close to zero. The net radiative energy fluxes into the surface and the surface latent heat transported into the atmosphere are about 113 and 86 Watts per square meter, respectively. The estimated atmospheric and surface heat imbalances are about -8 9 Watts per square meter, values that are within the uncertainties of surface radiation and sea surface turbulent flux estimates and likely systematic biases in the analyzed observations. The potential significant additional absorption of solar radiation within the atmosphere suggested by previous studies does not appear to be required to balance the energy budget the spurious heat imbalances in the current data are much smaller (about half) than those obtained previously and debated at about a decade ago. Progress in surface radiation and oceanic turbulent heat flux estimations from satellite measurements significantly reduces the bias errors in the observed global energy budgets of the climate system.

Effect of air velocity and direction for indirect evaporative cooling in tropical area

NASA Astrophysics Data System (ADS)

Ayodha Ajiwiguna, Tri; Nugraha Rismi, Fadhlin; Ramdlan Kirom, Mukhammad

2017-06-01

In this research, experimental study of heat absorption rate caused by indirect evaporative cooling is performed by varying the velocity and direction of air. The ambient is at average temperature and relative humidity of 28.7 °C and 78% respectively. The experiment is conducted by attaching wet medium on the top of material reference plate with the dimension of 14 x 8 cm with 5 mm thickness. To get evaporative cooling effect, the air flow is directed to the wet medium with velocity from 1.6 m/s to 3.4 m/s with the increment of 0.2 m/s. The direction of air is set 0° (parallel), 45° (inclined), and 90° (perpendicular) to the wet medium surface. While the experiment is being performed, the air temperature, top and bottom of plate temperature are measured simultaneously after steady state condition is established. Based on the measurement result, heat absorption is calculated by analysing the heat conduction on the material reference. The result shows that the heat absorption rate is increased by higher velocity. Perpendicular direction of air flow results the highest cooling capacity compared with other direction. The maximum heat absorption rate is achieved at 13.9 Watt with 3.4 m/s velocity and perpendicular direction of air.

Scaling analysis for the direct reactor auxiliary cooling system for FHRs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lv, Q.; Kim, I. H.; Sun, X.

2015-04-01

The Direct Reactor Auxiliary Cooling System (DRACS) is a passive residual heat removal system proposed for the Fluoride-salt-cooled High-temperature Reactor (FHR) that combines the coated particle fuel and graphite moderator with a liquid fluoride salt as the coolant. The DRACS features three natural circulation/convection loops that rely on buoyancy as the driving force and are coupled via two heat exchangers, namely, the DRACS heat exchanger and the natural draft heat exchanger. A fluidic diode is employed to minimize the parasitic flow into the DRACS primary loop and correspondingly the heat loss to the DRACS during reactor normal operation, and tomore » activate the DRACS in accidents when the reactor is shut down. While the DRACS concept has been proposed, there are no actual prototypic DRACS systems for FHRs built or tested in the literature. In this paper, a detailed scaling analysis for the DRACS is performed, which will provide guidance for the design of scaled-down DRACS test facilities. Based on the Boussinesq assumption and one-dimensional flow formulation, the governing equations are non-dimensionalized by introducing appropriate dimensionless parameters. The key dimensionless numbers that characterize the DRACS system are obtained from the non-dimensional governing equations. Based on the dimensionless numbers and non-dimensional governing equations, similarity laws are proposed. In addition, a scaling methodology has been developed, which consists of a core scaling and a loop scaling. The consistency between the core and loop scaling is examined via the reference volume ratio, which can be obtained from both the core and loop scaling processes. The scaling methodology and similarity laws have been applied to obtain a scientific design of a scaled-down high-temperature DRACS test facility.« less

Updates to Multi-Dimensional Flux Reconstruction for Hypersonic Simulations on Tetrahedral Grids

NASA Technical Reports Server (NTRS)

Gnoffo, Peter A.

2010-01-01

The quality of simulated hypersonic stagnation region heating with tetrahedral meshes is investigated by using an updated three-dimensional, upwind reconstruction algorithm for the inviscid flux vector. An earlier implementation of this algorithm provided improved symmetry characteristics on tetrahedral grids compared to conventional reconstruction methods. The original formulation however displayed quantitative differences in heating and shear that were as large as 25% compared to a benchmark, structured-grid solution. The primary cause of this discrepancy is found to be an inherent inconsistency in the formulation of the flux limiter. The inconsistency is removed by employing a Green-Gauss formulation of primitive gradients at nodes to replace the previous Gram-Schmidt algorithm. Current results are now in good agreement with benchmark solutions for two challenge problems: (1) hypersonic flow over a three-dimensional cylindrical section with special attention to the uniformity of the solution in the spanwise direction and (2) hypersonic flow over a three-dimensional sphere. The tetrahedral cells used in the simulation are derived from a structured grid where cell faces are bisected across the diagonal resulting in a consistent pattern of diagonals running in a biased direction across the otherwise symmetric domain. This grid is known to accentuate problems in both shock capturing and stagnation region heating encountered with conventional, quasi-one-dimensional inviscid flux reconstruction algorithms. Therefore the test problems provide a sensitive indicator for algorithmic effects on heating. Additional simulations on a sharp, double cone and the shuttle orbiter are then presented to demonstrate the capabilities of the new algorithm on more geometrically complex flows with tetrahedral grids. These results provide the first indication that pure tetrahedral elements utilizing the updated, three-dimensional, upwind reconstruction algorithm may be used for the simulation of heating and shear in hypersonic flows in upwind, finite volume formulations.

Multi-stage flash degaser

DOEpatents

Rapier, P.M.

1980-06-26

A multi-stage flash degaser is incorporated in an energy conversion system having a direct-contact, binary-fluid heat exchanger to remove essentially all of the noncondensable gases from geothermal brine ahead of the direct-contact binary-fluid heat exchanger in order that the heat exchanger and a turbine and condenser of the system can operate at optimal efficiency.

Comparison of Direct Solar Energy to Resistance Heating for Carbothermal Reduction of Regolith

NASA Technical Reports Server (NTRS)

Muscatello, Anthony C.; Gustafson, Robert J.

2011-01-01

A comparison of two methods of delivering thermal energy to regolith for the carbo thermal reduction process has been performed. The comparison concludes that electrical resistance heating is superior to direct solar energy via solar concentrators for the following reasons: (1) the resistance heating method can process approximately 12 times as much regolith using the same amount of thermal energy as the direct solar energy method because of superior thermal insulation; (2) the resistance heating method is more adaptable to nearer-term robotic exploration precursor missions because it does not require a solar concentrator system; (3) crucible-based methods are more easily adapted to separation of iron metal and glass by-products than direct solar energy because the melt can be poured directly after processing instead of being remelted; and (4) even with projected improvements in the mass of solar concentrators, projected photovoltaic system masses are expected to be even lower.

Heat rejection system

DOEpatents

Smith, Gregory C.; Tokarz, Richard D.; Parry, Jr., Harvey L.; Braun, Daniel J.

1980-01-01

A cooling system for rejecting waste heat consists of a cooling tower incorporating a plurality of coolant tubes provided with cooling fins and each having a plurality of cooling channels therein, means for directing a heat exchange fluid from the power plant through less than the total number of cooling channels to cool the heat exchange fluid under normal ambient temperature conditions, means for directing water through the remaining cooling channels whenever the ambient temperature rises above the temperature at which dry cooling of the heat exchange fluid is sufficient and means for cooling the water.

A comparison of microwave versus direct solar heating for lunar brick production

NASA Technical Reports Server (NTRS)

Yankee, S. J.; Strenski, D. G.; Pletka, B. J.; Patil, D. S.; Mutsuddy, B. C.

1990-01-01

Two processing techniques considered suitable for producing bricks from lunar regolith are examined: direct solar heating and microwave heating. An analysis was performed to compare the two processes in terms of the amount of power and time required to fabricate bricks of various sizes. Microwave heating was shown to be significantly faster than solar heating for rapid production of realistic-size bricks. However, the relative simplicity of the solar collector(s) used for the solar furnace compared to the equipment necessary for microwave generation may present an economic tradeoff.

Direct-heating solar-collector dump valve

NASA Technical Reports Server (NTRS)

Howikman, T. C.

1977-01-01

Five-port ganged valve isolates collector from primary load system pressure and drains collectors, allowing use of direct heating with all its advantages. Valve is opened and closed by same switch that controls pump or by temperature sensor set at O C, while providing direct dump option.

Old and new facts about hyperthermia-induced modulations of the immune system.

PubMed

Frey, Benjamin; Weiss, Eva-Maria; Rubner, Yvonne; Wunderlich, Roland; Ott, Oliver J; Sauer, Rolf; Fietkau, Rainer; Gaipl, Udo S

2012-01-01

Hyperthermia (HT) is a potent sensitiser for radiotherapy (RT) and chemotherapy (CT) and has been proven to modulate directly or indirectly cells of the innate and adaptive immune system. We will focus in this article on how anti-tumour immunity can be induced by HT. In contrast to some in vitro assays, in vivo examinations showed that natural killer cells and phagocytes like granulocytes are directly activated against the tumour by HT. Since heat also activates dendritic cells (DCs), HT should be combined with further death stimuli (RT, CT or immune therapy) to allocate tumour antigen, derived from, for example, necrotic tumour cells, for uptake by DCs. We will outline that induction of immunogenic tumour cells and direct tumour cell killing by HT in combination with other therapies contributes to immune activation against the tumour. Studies will be presented showing that non-beneficial effects of HT on immune cells are mostly timely restricted. A special focus is set on immune activation mediated by extracellular present heat shock proteins (HSPs) carrying tumour antigens and further danger signals released by dying tumour cells. Local HT treatment in addition to further stress stimuli exerts abscopal effects and might be considered as in situ tumour vaccination. An increased natural killer (NK) cell activity, lymphocyte infiltration and HSP-mediated induction of immunogenic tumour cells have been observed in patients. Treatments with the addition of HT therefore can be considered as a personalised cancer treatment approach by specifically activating the immune system against the individual unique tumour.

Thermionic cogeneration burner design

NASA Astrophysics Data System (ADS)

Miskolczy, G.; Goodale, D.; Moffat, A. L.; Morgan, D. T.

Since thermionic converters receive heat at very high temperatures (approximately 1800 K) and reject heat at moderately high temperatures (approximately 800 K), they are useful for cogeneration applications involving high temperature processes. The electric power from thermionic converters is produced as a high amperage, low-voltage direct current. An ideal cogeneration application would be to utilize the reject heat at the collector temperature and the electricity without power conditioning. A cogeneration application in the edible oil industry fulfills both of these requirements since both direct heat and hydrogen gas are required in the hydrogenation of the oils. In this application, the low-voltage direct current would be used in a hydrogen electrolyzer.

The effect of heating direction on flow boiling heat transfer of R134a in micro-channels

NASA Astrophysics Data System (ADS)

Xu, Mingchen; Jia, Li; Dang, Chao; Peng, Qi

2017-04-01

This paper presents effects of heating directions on heat transfer performance of R134a flow boiling in micro- channel heat sink. The heat sink has 30 parallel rectangular channels with cross-sectional dimensions of 500μm width 500μm depth and 30mm length. The experimental operation condition ranges of the heat flux and the mass flux were 13.48 to 82.25 W/cm2 and 373.3 to 1244.4 kg/m2s respectively. The vapor quality ranged from 0.07 to 0.93. The heat transfer coefficients of top heating and bottom heating both were up to 25 kW/m2 K. Two dominate transfer mechanisms of nucleate boiling and convection boiling were observed according to boiling curves. The experimental results indicated that the heat transfer coefficient of bottom heating was 13.9% higher than top heating in low heat flux, while in high heat flux, the heat transfer coefficient of bottom heating was 9.9%.higher than the top heating, because bubbles were harder to divorce the heating wall. And a modified correlation was provided to predict heat transfer of top heating.

Controlled preparation of M(Ag, Au)/TiO2 through sulfydryl-assisted method for enhanced photocatalysis

NASA Astrophysics Data System (ADS)

Xia, Hongbo; Wu, Suli; Bi, Jiajie; Zhang, Shufen

2017-11-01

Here a simple and effective method was explored to fabricate M/TiO2 (M = Ag, Au) composites, which required neither pre-treatment of TiO2 nor any additives as reducing agent. Using amorphous TiO2 spheres functionalized with SH groups as starting materials, the noble metallic ions (Ag, Au) can be adsorbed by TiO2 due to their special affinity with SH groups, which is beneficial to the uniform dispersion of metallic ions on the surface of TiO2. Then the adsorbed ions were reduced to form noble metal nanoparticles by heating process (95 °C) directly without additive as reduction agent. Meanwhile, the amorphous TiO2 was transformed into anatase phase during the heating process. Thus, the transformation of TiO2 along with the reduction of noble metallic ions (Ag, Au) was simultaneously carried out by heating. The XRD patterns proved the formation of anatase TiO2 after heating. The characterizations of XPS and TEM proved the formation of Ag and Au nanoparticles on the surface of TiO2. The element mapping indicated that Ag nanoparticles are dispersed uniformly on the surface of TiO2. The photocatalytic activity of the composites has been investigated by the degradation of methyl orange under visible light irradiation. The results showed that when Ag/TiO2 (2.8 wt%) was used as photocatalyst, about 98% of the MO molecules were degraded in 70 min.

Inducible Transposition of a Heat-Activated Retrotransposon in Tissue Culture.

PubMed

Masuta, Yukari; Nozawa, Kosuke; Takagi, Hiroki; Yaegashi, Hiroki; Tanaka, Keisuke; Ito, Tasuku; Saito, Hideyuki; Kobayashi, Hisato; Matsunaga, Wataru; Masuda, Seiji; Kato, Atsushi; Ito, Hidetaka

2017-02-01

A transposition of a heat-activated retrotransposon named ONSEN required compromise of a small RNA-mediated epigenetic regulation that includes RNA-directed DNA methylation (RdDM) machinery after heat treatment. In the current study, we analyzed the transcriptional and transpositional activation of ONSEN to better understand the underlying molecular mechanism involved in the maintenance and/or induction of transposon activation in plant tissue culture. We found the transposition of heat-primed ONSEN during tissue culture independently of RdDM mutation. The heat activation of ONSEN transcripts was not significantly up-regulated in tissue culture compared with that in heat-stressed seedlings, indicating that the transposition of ONSEN was regulated independently of the transcript level. RdDM-related genes were up-regulated by heat stress in both tissue culture and seedlings. The level of DNA methylation of ONSEN did not show any change in tissue culture, and the amount of ONSEN-derived small RNAs was not affected by heat stress. The results indicated that the transposition of ONSEN was regulated by an alternative mechanism in addition to the RdDM-mediated epigenetic regulation in tissue culture. We applied the tissue culture-induced transposition of ONSEN to Japanese radish, an important breeding species of the family Brassicaceae. Several new insertions were detected in a regenerated plant derived from heat-stressed tissues and its self-fertilized progeny, revealing the possibility of molecular breeding without genetic modification. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Class I and II Small Heat Shock Proteins Together with HSP101 Protect Protein Translation Factors during Heat Stress1[OPEN

PubMed Central

Basha, Eman; Fowler, Mary E.; Kim, Minsoo; Bordowitz, Juliana; Katiyar-Agarwal, Surekha

2016-01-01

The ubiquitous small heat shock proteins (sHSPs) are well documented to act in vitro as molecular chaperones to prevent the irreversible aggregation of heat-sensitive proteins. However, the in vivo activities of sHSPs remain unclear. To investigate the two most abundant classes of plant cytosolic sHSPs (class I [CI] and class II [CII]), RNA interference (RNAi) and overexpression lines were created in Arabidopsis (Arabidopsis thaliana) and shown to have reduced and enhanced tolerance, respectively, to extreme heat stress. Affinity purification of CI and CII sHSPs from heat-stressed seedlings recovered eukaryotic translation elongation factor (eEF) 1B (α-, β-, and γ-subunits) and eukaryotic translation initiation factor 4A (three isoforms), although the association with CI sHSPs was stronger and additional proteins involved in translation were recovered with CI sHSPs. eEF1B subunits became partially insoluble during heat stress and, in the CI and CII RNAi lines, showed reduced recovery to the soluble cell fraction after heat stress, which was also dependent on HSP101. Furthermore, after heat stress, CI sHSPs showed increased retention in the insoluble fraction in the CII RNAi line and vice versa. Immunolocalization revealed that both CI and CII sHSPs were present in cytosolic foci, some of which colocalized with HSP101 and with eEF1Bγ and eEF1Bβ. Thus, CI and CII sHSPs have both unique and overlapping functions and act either directly or indirectly to protect specific translation factors in cytosolic stress granules. PMID:27474115

An artificial HSE promoter for efficient and selective detection of heat shock pathway activity.

PubMed

Ortner, Viktoria; Ludwig, Alfred; Riegel, Elisabeth; Dunzinger, Sarah; Czerny, Thomas

2015-03-01

Detection of cellular stress is of major importance for the survival of cells. During evolution, a network of stress pathways developed, with the heat shock (HS) response playing a major role. The key transcription factor mediating HS signalling activity in mammalian cells is the HS factor HSF1. When activated it binds to the heat shock elements (HSE) in the promoters of target genes like heat shock protein (HSP) genes. They are induced by HSF1 but in addition they integrate multiple signals from different stress pathways. Here, we developed an artificial promoter consisting only of HSEs and therefore selectively reacting to HSF-mediated pathway activation. The promoter is highly inducible but has an extreme low basal level. Direct comparison with the HSPA1A promoter activity indicates that heat-dependent expression can be fully recapitulated by isolated HSEs in human cells. Using this sensitive reporter, we measured the HS response for different temperatures and exposure times. In particular, long heat induction times of 1 or 2 h were compared with short heat durations down to 1 min, conditions typical for burn injuries. We found similar responses to both long and short heat durations but at completely different temperatures. Exposure times of 2 h result in pathway activation at 41 to 44 °C, whereas heat pulses of 1 min lead to a maximum HS response between 47 and 50 °C. The results suggest that the HS response is initiated by a combination of temperature and exposure time but not by a certain threshold temperature.

Molecular wires acting as quantum heat ratchets.

PubMed

Zhan, Fei; Li, Nianbei; Kohler, Sigmund; Hänggi, Peter

2009-12-01

We explore heat transfer in molecular junctions between two leads in the absence of a finite net thermal bias. The application of an unbiased time-periodic temperature modulation of the leads entails a dynamical breaking of reflection symmetry, such that a directed heat current may emerge (ratchet effect). In particular, we consider two cases of adiabatically slow driving, namely, (i) periodic temperature modulation of only one lead and (ii) temperature modulation of both leads with an ac driving that contains a second harmonic, thus, generating harmonic mixing. Both scenarios yield sizable directed heat currents, which should be detectable with present techniques. Adding a static thermal bias allows one to compute the heat current-thermal load characteristics, which includes the ratchet effect of negative thermal bias with positive-valued heat flow against the thermal bias, up to the thermal stop load. The ratchet heat flow in turn generates also an electric current. An applied electric stop voltage, yielding effective zero electric current flow, then mimics a solely heat-ratchet-induced thermopower ("ratchet Seebeck effect"), although no net thermal bias is acting. Moreover, we find that the relative phase between the two harmonics in scenario (ii) enables steering the net heat current into a direction of choice.

Genetic evaluations for growth heat tolerance in Angus cattle.

PubMed

Bradford, H L; Fragomeni, B O; Bertrand, J K; Lourenco, D A L; Misztal, I

2016-10-01

The objectives were to assess the impact of heat stress and to develop a model for genetic evaluation of growth heat tolerance in Angus cattle. The American Angus Association provided weaning weight (WW) and yearling weight (YW) data, and records from the Upper South region were used because of the hot climatic conditions. Heat stress was characterized by a weaning (yearling) heat load function defined as the mean temperature-humidity index (THI) units greater than 75 (70) for 30 (150) d prior to the weigh date. Therefore, a weaning (yearling) heat load of 5 units corresponded to 80 (75) for the corresponding period prior to the weigh date. For all analyses, 82,669 WW and 69,040 YW were used with 3 ancestral generations in the pedigree. Univariate models were a proxy for the Angus growth evaluation, and reaction norms using 2 B-splines for heat load were fit separately for weaning and yearling heat loads. For both models, random effects included direct genetic, maternal genetic, maternal permanent environment (WW only), and residual. Fixed effects included a linear age covariate, age-of-dam class (WW only), and contemporary group for both models and fixed regressions on the B-splines in the reaction norm. Direct genetic correlations for WW were strong for modest heat load differences but decreased to less than 0.50 for large differences. Reranking of proven sires occurred for only WW direct effects for the reaction norms with extreme heat load differences. Conversely, YW results indicated little effect of heat stress on genetic merit. Therefore, weaning heat tolerance was a better candidate for developing selection tools. Maternal heritabilities were consistent across heat loads, and maternal genetic correlations were greater than 0.90 for nearly all heat load combinations. No evidence existed for a genotype × environment interaction for the maternal component of growth. Overall, some evidence exists for phenotypic plasticity for the direct genetic effects of WW, but traditional national cattle evaluations are likely adequately ranking sires for nonextreme environmental conditions.

Energy savings for heat-island reduction strategies in Chicago and Houston (including updates for Baton Rouge, Sacramento, and Salt Lake City)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Konopacki, S.; Akbari, H.

2002-02-28

In 1997, the U.S. Environmental Protection Agency (EPA) established the ''Heat Island Reduction Initiative'' to quantify the potential benefits of Heat-Island Reduction (HIR) strategies (i.e., shade trees, reflective roofs, reflective pavements and urban vegetation) to reduce cooling-energy use in buildings, lower the ambient air temperature and improve urban air quality in cities, and reduce CO2 emissions from power plants. Under this initiative, the Urban Heat Island Pilot Project (UHIPP) was created with the objective of investigating the potential of HIR strategies in residential and commercial buildings in three initial UHIPP cities: Baton Rouge, LA; Sacramento, CA; and Salt Lake City,more » UT. Later two other cities, Chicago, IL and Houston, TX were added to the UHIPP. In an earlier report we summarized our efforts to calculate the annual energy savings, peak power avoidance, and annual CO2 reduction obtainable from the introduction of HIR strategies in the initial three cities. This report summarizes the results of our study for Chicago and Houston. In this analysis, we focused on three building types that offer the highest potential savings: single-family residence, office and retail store. Each building type was characterized in detail by vintage and system type (i.e., old and new building constructions, and gas and electric heat). We used the prototypical building characteristics developed earlier for each building type and simulated the impact of HIR strategies on building cooling- and heating-energy use and peak power demand using the DOE-2.1E model. Our simulations included the impact of (1) strategically-placed shade trees near buildings [direct effect], (2) use of high-albedo roofing material on the building [direct effect], (3) urban reforestation with high-albedo pavements and building surfaces [indirect effect] and (4) combined strategies 1, 2, and 3 [direct and indirect effects]. We then estimated the total roof area of air-conditioned buildings in each city using readily obtainable data to calculate the metropolitan-wide impact of HIR strategies. The results show that in Chicago, potential annual energy savings of $30M could be realized by ratepayers from the combined direct and indirect effects of HIR strategies. Additionally, peak power avoidance is estimated at 400 MW and the reduction in annual carbon emissions at 58 ktC. In Houston, the potential annual energy savings are estimated at $82M, with an avoidance of 730 MW in peak power and a reduction in annual carbon emissions of 170 ktC.« less

Skin and muscle components of forearm blood flow in directly heated resting man.

NASA Technical Reports Server (NTRS)

Detry, J.-M. R.; Brengelmann, G. L.; Rowell, L. B.; Wyss, C.

1972-01-01

Changes in forearm muscle blood flow (FMBF) during direct whole-body heating were measured in 17 normal subjects using three different methods. We conclude that FMBF is not increased by direct whole-body heating. Since renal and splanchnic blood flow fall 30% under these conditions, maximal total skin blood flow in 12 previously studied subjects can be estimated from the rise in cardiac output to be 7.6 L/min (3.0-11.1 L/min).

Photon Doppler Velocimeter to Measure Entrained Additive Manufactured Bulk Metal Powders in Hot Subsonic and Supersonic Oxygen Gas

NASA Technical Reports Server (NTRS)

Tylka, Jonathan

2016-01-01

Parts produced by additive manufacturing, particularly selective laser melting (SLM), have been shown to silt metal particulate even after undergoing stringent precision aerospace cleaning processes (Lowrey 2016). As printed parts are used in oxygen systems with increased pressures, temperatures, and gas velocity, the risk of ignition by particle impact, the most common direct ignition source of metals in oxygen, substantially increases. The White Sands Test Facility (WSTF), in collaboration with Marshall Space Flight Center (MSFC), desires to test the ignitability of SLM metals by particle impact in heated oxygen. The existing test systems rely on gas velocity calculations to infer particle velocity in both subsonic and supersonic particle impact systems. Until now, it was not possible to directly measure particle velocity. To increase the fidelity of planned SLM ignition studies, it is necessary to validate that the Photon Doppler Velocimetry(PDV) test system can accurately measure particle velocity.

Experimental Space Shuttle Orbiter Studies to Acquire Data for Code and Flight Heating Model Validation

NASA Technical Reports Server (NTRS)

Wadhams, T. P.; Holden, M. S.; MacLean, M. G.; Campbell, Charles

2010-01-01

In an experimental study to obtain detailed heating data over the Space Shuttle Orbiter, CUBRC has completed an extensive matrix of experiments using three distinct models and two unique hypervelocity wind tunnel facilities. This detailed data will be employed to assess heating augmentation due to boundary layer transition on the Orbiter wing leading edge and wind side acreage with comparisons to computational methods and flight data obtained during the Orbiter Entry Boundary Layer Flight Experiment and HYTHIRM during STS-119 reentry. These comparisons will facilitate critical updates to be made to the engineering tools employed to make assessments about natural and tripped boundary layer transition during Orbiter reentry. To achieve the goals of this study data was obtained over a range of Mach numbers from 10 to 18, with flight scaled Reynolds numbers and model attitudes representing key points on the Orbiter reentry trajectory. The first of these studies were performed as an integral part of Return to Flight activities following the accident that occurred during the reentry of the Space Shuttle Columbia (STS-107) in February of 2003. This accident was caused by debris, which originated from the foam covering the external tank bipod fitting ramps, striking and damaging critical wing leading edge heating tiles that reside in the Orbiter bow shock/wing interaction region. During investigation of the accident aeroheating team members discovered that only a limited amount of experimental wing leading edge data existed in this critical peak heating area and a need arose to acquire a detailed dataset of heating in this region. This new dataset was acquired in three phases consisting of a risk mitigation phase employing a 1.8% scale Orbiter model with special temperature sensitive paint covering the wing leading edge, a 0.9% scale Orbiter model with high resolution thin-film instrumentation in the span direction, and the primary 1.8% scale Orbiter model with detailed thin-film resolution in both the span and chord direction in the area of peak heating. Additional objectives of this first study included: obtaining natural or tripped turbulent wing leading edge heating levels, assessing the effectiveness of protuberances and cavities placed at specified locations on the orbiter over a range of Mach numbers and Reynolds numbers to evaluate and compare to existing engineering and computational tools, obtaining cavity floor heating to aid in the verification of cavity heating correlations, acquiring control surface deflection heating data on both the main body flap and elevons, and obtain high speed schlieren videos of the interaction of the orbiter nose bow shock with the wing leading edge. To support these objectives, the stainless steel 1.8% scale orbiter model in addition to the sensors on the wing leading edge was instrumented down the windward centerline, over the wing acreage on the port side, and painted with temperature sensitive paint on the starboard side wing acreage. In all, the stainless steel 1.8% scale Orbiter model was instrumented with over three-hundred highly sensitive thin-film heating sensors, two-hundred of which were located in the wing leading edge shock interaction region. Further experimental studies will also be performed following the successful acquisition of flight data during the Orbiter Entry Boundary Layer Flight Experiment and HYTHIRM on STS-119 at specific data points simulating flight conditions and geometries. Additional instrumentation and a protuberance matching the layout present during the STS-119 boundary layer transition flight experiment were added with testing performed at Mach number and Reynolds number conditions simulating conditions experienced in flight. In addition to the experimental studies, CUBRC also performed a large amount of CFD analysis to confirm and validate not only the tunnel freestream conditions, but also 3D flows over the orbiter acreage, wing leading edge, and controlurfaces to assess data quality, shock interaction locations, and control surface separation regions. This analysis is a standard part of any experimental program at CUBRC, and this information was of key importance for post-test data quality analysis and understanding particular phenomena seen in the data. All work during this effort was sponsored and paid for by the NASA Space Shuttle Program Office at the Johnson Space Center in Houston, Texas.

Heat sinking for printed circuitry

DOEpatents

Wilson, S.K.; Richardson, G.; Pinkerton, A.L.

1984-09-11

A flat pak or other solid-state device mounted on a printed circuit board directly over a hole extends therethrough so that the bottom of the pak or device extends beyond the bottom of the circuit board. A heat sink disposed beneath the circuit board contacts the bottom of the pak or device and provides direct heat sinking thereto. Pressure may be applied to the top of the pak or device to assure good mechanical and thermal contact with the heat sink.

76 FR 9650 - Approval and Promulgation of Air Quality Implementation Plans; Maryland; Amendment to the...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-02-22

... water and fuel-burning installations that involve direct heat exchange. Fuel-burning installations, such... (British thermal unit) Btu per hour heat input or the sulfur content of the fuel. Since a ``furnace'' is usually direct heat exchange, the State of Maryland concludes that it should not be included in the...

Hard X-ray Detectability of Small Impulsive Heating Events in the Solar Corona

NASA Astrophysics Data System (ADS)

Glesener, L.; Klimchuk, J. A.; Bradshaw, S. J.; Marsh, A.; Krucker, S.; Christe, S.

2015-12-01

Impulsive heating events ("nanoflares") are a candidate to supply the solar corona with its ~2 MK temperature. These transient events can be studied using extreme ultraviolet and soft X-ray observations, among others. However, the impulsive events may occur in tenuous loops on small enough timescales that the heating is essentially not observed due to ionization timescales, and only the cooling phase is observed. Bremsstrahlung hard X-rays could serve as a more direct and prompt indicator of transient heating events. A hard X-ray spacecraft based on the direct-focusing technology pioneered by the Focusing Optics X-ray Solar Imager (FOXSI) sounding rocket could search for these direct signatures. In this work, we use the hydrodynamical EBTEL code to simulate differential emission measures produced by individual heating events and by ensembles of such events. We then directly predict hard X-ray spectra and consider their observability by a future spaceborne FOXSI, and also by the RHESSI and NuSTAR spacecraft.

A comparison of direct heating during radiofrequency and microwave ablation in ex vivo liver

PubMed Central

Andreano, Anita; Brace, Christopher L

2012-01-01

Purpose To determine the magnitude and spatial distribution of temperature elevations when using 480 kHz RF and 2.45 GHz microwave energy in ex vivo liver models. Materials and Methods A total of sixty heating cycles (20 s at 90 W) were performed in normal, RF ablated and microwave ablated liver tissues (n=10 RF and n=10 microwave in each tissue type). Heating cycles were performed using a 480 kHz generator and 3 cm cooled-tip electrode (RF) or a 2.45 GHz generator and 14-gauge monopole (microwave) and designed to isolate direct heating from each energy type. Tissue temperatures were measured using fiberoptic thermosensors 5, 10 and 15 mm radially from the ablation applicator at the depth of maximal heating. Power delivered, sensor location, heating rates and maximal temperatures were compared using mixed effects regression models. Results No significant differences were noted in mean power delivered or thermosensor locations between RF and microwave heating groups (P>0.05). Microwaves produced significantly more rapid heating than RF at 5, 10 and 15mm in normal tissue (3.0 vs. 0.73, 0.85 vs. 0.21 and 0.17 vs. 0.09 °C/s; P<.05); and at 5 and 10mm in ablated tissues (2.3 ± 1.4 vs. 0.7 ± 0.3, 0.5 ± 0.3 vs. 0.2 ± 0.0 C/s, P<.05). The radial depth of heating was approximately 5mm greater for microwaves than RF. Conclusions Direct heating obtained with 2.45 GHz microwave energy using a single needle-like applicator is faster and covers a larger volume of tissue than 480 kHz RF energy. Keywords: microwave ablation, direct heating, thermal ablation PMID:22572764

Heat transfer direction dependence of heat transfer coefficients in annuli

NASA Astrophysics Data System (ADS)

Prinsloo, Francois P. A.; Dirker, Jaco; Meyer, Josua P.

2018-04-01

In this experimental study the heat transfer phenomena in concentric annuli in tube-in-tube heat exchangers at different annular Reynolds numbers, annular diameter ratios, and inlet fluid temperatures using water were considered. Turbulent flow with Reynolds numbers ranging from 15,000 to 45,000, based on the average bulk fluid temperature was tested at annular diameter ratios of 0.327, 0.386, 0.409 and 0.483 with hydraulic diameters of 17.00, 22.98, 20.20 and 26.18 mm respectively. Both heated and cooled annuli were investigated by conducting tests at a range of inlet temperatures between 10 °C to 30 °C for heating cases, and 30 °C to 50 °C for cooling cases. Of special interest was the direct measurement of local wall temperatures on the heat transfer surface, which is often difficult to obtain and evasive in data-sets. Continuous verification and re-evaluation of temperatures measurements were performed via in-situ calibration. It is shown that inlet fluid temperature and the heat transfer direction play significant roles on the magnitude of the heat transfer coefficient. A new adjusted Colburn j-factor definition is presented to describe the heating and cooling cases and is used to correlate the 894 test cases considered in this study.

Antimisting kerosene: Low temperature degradation and blending

NASA Technical Reports Server (NTRS)

Yavrouian, A.; Parikh, P.; Sarohia, V.

1988-01-01

The inline filtration characteristics of freshly blended and degraded antimisting fuels (AMK) at low temperature are examined. A needle valve degrader was modified to include partial recirculation of degraded fuel and heat addition in the bypass loop. A pressure drop across the needle valve of up to 4,000 psi was used. The pressure drop across a 325 mesh filter screen placed inline with the degrader and directly downstream of the needle valve was measured as a function of time for different values of pressure drop across the needle valve. A volume flux of 1 gpm/sq in was employed based on the frontal area of the screen. It was found that, at ambient temperatures, freshly blended AMK fuel could be degraded using a single pass degradation at 4,000 psi pressure drop across the needle valve to give acceptable filterability performance. At fuel temperatures below -20 C, degradation becomes increasingly difficult and a single pass technique results in unacceptable filtration performance. Recirculation of a fraction of the degraded fuel and heat addition in the bypass loop improved low temperature degradation performance. The problem is addressed of blending the AMK additive with Jet A at various base fuel temperatures.

Direct Digital Control of HVAC (Heating, Ventilating, and Air Conditioning Equipment (User’s Guide)

DTIC Science & Technology

1985-01-01

reset, load shedding, chiller optimization , VAV fan synchronization, and optimum start/stop. The prospective buyer of a DDC system should investigate...current and accurate drawings for a conventional, built-up control system such as that illustrated in Fig- ure 4. Data on setpoints , reset schedules, and...are always available in the form of the computer program code (Figure 7). In addition to the control logic, setpoint and other data are readily

Hybrid solar central receiver for combined cycle power plant

DOEpatents

Bharathan, Desikan; Bohn, Mark S.; Williams, Thomas A.

1995-01-01

A hybrid combined cycle power plant including a solar central receiver for receiving solar radiation and converting it to thermal energy. The power plant includes a molten salt heat transfer medium for transferring the thermal energy to an air heater. The air heater uses the thermal energy to preheat the air from the compressor of the gas cycle. The exhaust gases from the gas cycle are directed to a steam turbine for additional energy production.

Process-Structure-Property Relationships for 316L Stainless Steel Fabricated by Additive Manufacturing and Its Implication for Component Engineering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Nancy; Yee, J.; Zheng, B.

We investigate the process-structure-property relationships for 316L stainless steel prototyping utilizing 3-D laser engineered net shaping (LENS), a commercial direct energy deposition additive manufacturing process. Our study concluded that the resultant physical metallurgy of 3-D LENS 316L prototypes is dictated by the interactive metallurgical reactions, during instantaneous powder feeding/melting, molten metal flow and liquid metal solidification. This study also showed 3-D LENS manufacturing is capable of building high strength and ductile 316L prototypes due to its fine cellular spacing from fast solidification cooling, and the well-fused epitaxial interfaces at metal flow trails and interpass boundaries. However, without further LENS processmore » control and optimization, the deposits are vulnerable to localized hardness variation attributed to heterogeneous microstructure, i.e., the interpass heat-affected zone (HAZ) from repetitive thermal heating during successive layer depositions. Most significantly, the current deposits exhibit anisotropic tensile behavior, i.e., lower strain and/or premature interpass delamination parallel to build direction (axial). This anisotropic behavior is attributed to the presence of interpass HAZ, which coexists with flying feedstock inclusions and porosity from incomplete molten metal fusion. Our current observations and findings contribute to the scientific basis for future process control and optimization necessary for material property control and defect mitigation.« less

Process-Structure-Property Relationships for 316L Stainless Steel Fabricated by Additive Manufacturing and Its Implication for Component Engineering

DOE PAGES

Yang, Nancy; Yee, J.; Zheng, B.; ...

2016-12-08

We investigate the process-structure-property relationships for 316L stainless steel prototyping utilizing 3-D laser engineered net shaping (LENS), a commercial direct energy deposition additive manufacturing process. Our study concluded that the resultant physical metallurgy of 3-D LENS 316L prototypes is dictated by the interactive metallurgical reactions, during instantaneous powder feeding/melting, molten metal flow and liquid metal solidification. This study also showed 3-D LENS manufacturing is capable of building high strength and ductile 316L prototypes due to its fine cellular spacing from fast solidification cooling, and the well-fused epitaxial interfaces at metal flow trails and interpass boundaries. However, without further LENS processmore » control and optimization, the deposits are vulnerable to localized hardness variation attributed to heterogeneous microstructure, i.e., the interpass heat-affected zone (HAZ) from repetitive thermal heating during successive layer depositions. Most significantly, the current deposits exhibit anisotropic tensile behavior, i.e., lower strain and/or premature interpass delamination parallel to build direction (axial). This anisotropic behavior is attributed to the presence of interpass HAZ, which coexists with flying feedstock inclusions and porosity from incomplete molten metal fusion. Our current observations and findings contribute to the scientific basis for future process control and optimization necessary for material property control and defect mitigation.« less

Buprenorphine Transdermal Patch

MedlinePlus

... it to direct heat such as heating pads, electric blankets, heat lamps, saunas, hot tubs, and heated ... may make you drowsy. Do not drive a car, operate machinery, or do other possibly dangerous activities ...

Selegiline Transdermal Patch

MedlinePlus

... patch from direct heat such as heating pads, electric blankets, heat lamps, saunas, hot tubs, and heated ... may make you drowsy. Do not drive a car or operate machinery until you know how this ...

Direct coupling of packed column supercritical fluid chromatography to continuous corona discharge ion mobility spectrometry.

PubMed

Rahmanian, A; Ghaziaskar, H S; Khayamian, T

2013-01-11

In this study, packed column supercritical fluid chromatography (SFC) was directly coupled to a continuous corona discharge (CD) ion mobility spectrometer (IMS) with several modifications. The main advantage of the developed detector is its capability to introduce full column effluent up to 2000 mL min(-1) CO(2) gas directly into the IMS cell relative to 40 mL min(-1) CO(2) gas as a maximum tolerance, reported for the previous IMS detectors. This achievement was made possible because of using corona discharge instead of (63)Ni as an ionization source and locating the inlet and outlet of the CO(2) gas in the counter electrode of the CD in opposite direction. In addition, a heated interface was placed between back pressure regulator (BPR) and the IMS cell to heat the output of the BPR for introducing sample as the gas phase into the IMS cell. Furthermore, a make-up methanol flow was introduced between the column outlet and BPR to provide a more uniform flow through the BPR and also to prevent freezing and deposition of the analytes in the BPR. The performance of the SFC-CD-IMS was evaluated by analysis of testosterone, medroxyprogesterone, caffeine, and theophylline as test compounds and figures of merit for these compounds have been calculated. Copyright © 2012 Elsevier B.V. All rights reserved.

Dynamics of a reconnection-driven runaway ion tail in a reversed field pinch plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, J. K., E-mail: jkanders@wisc.edu; Kim, J.; Bonofiglo, P. J.

2016-05-15

While reconnection-driven ion heating is common in laboratory and astrophysical plasmas, the underlying mechanisms for converting magnetic to kinetic energy remain not fully understood. Reversed field pinch discharges are often characterized by rapid ion heating during impulsive reconnection, generating an ion distribution with an enhanced bulk temperature, mainly perpendicular to magnetic field. In the Madison Symmetric Torus, a subset of discharges with the strongest reconnection events develop a very anisotropic, high energy tail parallel to magnetic field in addition to bulk perpendicular heating, which produces a fusion neutron flux orders of magnitude higher than that expected from a Maxwellian distribution.more » Here, we demonstrate that two factors in addition to a perpendicular bulk heating mechanism must be considered to explain this distribution. First, ion runaway can occur in the strong parallel-to-B electric field induced by a rapid equilibrium change triggered by reconnection-based relaxation; this effect is particularly strong on perpendicularly heated ions which experience a reduced frictional drag relative to bulk ions. Second, the confinement of ions varies dramatically as a function of velocity. Whereas thermal ions are governed by stochastic diffusion along tearing-altered field lines (and radial diffusion increases with parallel speed), sufficiently energetic ions are well confined, only weakly affected by a stochastic magnetic field. High energy ions traveling mainly in the direction of toroidal plasma current are nearly classically confined, while counter-propagating ions experience an intermediate confinement, greater than that of thermal ions but significantly less than classical expectations. The details of ion confinement tend to reinforce the asymmetric drive of the parallel electric field, resulting in a very asymmetric, anisotropic distribution.« less

Experimental and analytical studies of high heat flux components for fusion experimental reactor

NASA Astrophysics Data System (ADS)

Araki, Masanori

1993-03-01

In this report, the experimental and analytical results concerning the development of plasma facing components of ITER are described. With respect to developing high heat removal structures for the divertor plates, an externally-finned swirl tube was developed based on the results of critical heat flux (CHF) experiments on various tube structures. As the result, the burnout heat flux, which also indicates incident CHF, of 41 (+/-) 1 MW/sq m was achieved in the externally-finned swirl tube. The applicability of existing CHF correlations based on uniform heating conditions was evaluated by comparing the CHF experimental data with the smooth and the externally-finned tubes under one-sided heating condition. As the results, experimentally determined CHF data for straight tube show good agreement, for the externally-finned tube, no existing correlations are available for prediction of the CHF. With respect to the evaluation of the bonds between carbon-based material and heat sink metal, results of brazing tests were compared with the analytical results by three dimensional model with temperature-dependent thermal and mechanical properties. Analytical results showed that residual stresses from brazing can be estimated by the analytical three directional stress values instead of the equivalent stress value applied. In the analytical study on the separatrix sweeping for effectively reducing surface heat fluxes on the divertor plate, thermal response of the divertor plate was analyzed under ITER relevant heat flux conditions and has been tested. As the result, it has been demonstrated that application of the sweeping technique is very effective for improvement in the power handling capability of the divertor plate and that the divertor mock-up has withstood a large number of additional cyclic heat loads.

Pneumatic Proboscis Heat-Flow Probe

NASA Technical Reports Server (NTRS)

Zacny, Kris; Hedlund, Magnus; Mumm, Eric; Shasho, Jeffrey; Chu, Philip; Kumar, Nishant

2013-01-01

Heat flow is a fundamental property of a planet, and provides significant constraints on the abundance of radiogenic isotopes, the thermal evolution and differentiation history, and the mechanical properties of the lithosphere. Heat-flow measurements are also essential in achieving at least four of the goals set out by the National Research Council for future lunar exploration. The heat-flow probe therefore directly addresses the goal of the Lunar Geophysical Network, which is to understand the interior structure and composition of the Moon. A key challenge for heat flow measurement is to install thermal sensors to the depths approximately equal to 3 m that are not influenced by the diurnal, annual, and longer-term fluctuations of the surface thermal environment. In addition, once deployed, the heat flow probe should cause little disturbance to the thermal regime of the surrounding regolith. A heat-flow probe system was developed that has two novel features: (1) it utilizes a pneumatic (gas) approach, excavates a hole by lofting the lunar soil out of the hole, and (2) deploys the heat flow probe, which utilizes a coiled up tape as a thermal probe to reach greater than 3-meter depth. The system is a game-changer for small lunar landers as it exhibits extremely low mass, volume, and simple deployment. The pneumatic system takes advantage of the helium gas used for pressurizing liquid propellant of the lander. Normally, helium is vented once the lander is on the surface, but it can be utilized for powering pneumatic systems. Should sufficient helium not be available, a simple gas delivery system may be taken specifically for the heat flow probe. Either way, the pneumatic heat flow probe system would be much lighter than other systems that entirely rely on the electrical power of the lander.

Utilizing Radioisotope Power System Waste Heat for Spacecraft Thermal Management

NASA Technical Reports Server (NTRS)

Pantano, David R.; Dottore, Frank; Geng, Steven M.; Schrieber, Jeffrey G.; Tobery, E. Wayne; Palko, Joseph L.

2005-01-01

One of the advantages of using a Radioisotope Power System (RPS) for deep space or planetary surface missions is the readily available waste heat, which can be used to maintain electronic components within a controlled temperature range, to warm propulsion tanks and mobility actuators, and to gasify liquid propellants. Previous missions using Radioisotope Thermoelectric Generators (RTGs) dissipated a very large quantity of waste heat due to the relatively low efficiency of the thermoelectric conversion technology. The next generation RPSs, such as the 110-watt Stirling Radioisotope Generator (SRG110) will have much higher conversion efficiencies than their predecessors and therefore may require alternate approaches to transferring waste heat to the spacecraft. RTGs, with efficiencies of approx. 6 to 7% and 200 C housing surface temperatures, would need to use large and heavy radiator heat exchangers to transfer the waste heat to the internal spacecraft components. At the same time, sensitive spacecraft instruments must be shielded from the thermal radiation by using the heat exchangers or additional shields. The SRG110, with an efficiency around 22% and 50 C nominal housing surface temperature, can use the available waste heat more efficiently by more direct heat transfer methods such as heat pipes, thermal straps, or fluid loops. The lower temperatures allow the SRG110 much more flexibility to the spacecraft designers in configuring the generator without concern of overheating nearby scientific instruments, thereby eliminating the need for thermal shields. This paper will investigate using a high efficiency SRG110 for spacecraft thermal management and outline potential methods in several conceptual missions (Lunar Rover, Mars Rover, and Titan Lander) to illustrate the advantages with regard to ease of assembly, less complex interfaces, and overall mass savings.

Boiling of multicomponent working fluids used in refrigeration and cryogenic systems

NASA Astrophysics Data System (ADS)

Mogorychny, V. I.; Dolzhikov, A. S.

2017-11-01

Working fluids based on mixtures are widely used in cryogenic and refrigeration engineering. One of the main elements of low-temperature units is a recuperative heat exchanger where the return flow cools the direct (cold regeneration is carrying out) resulting in continuous boiling and condensation of the multicomponent working fluid in the channels. The temperature difference between the inlet and outlet of the heat exchanger can be more than 100K, which leads to a strong change in thermophysical properties along its length. In addition, the fraction of the liquid and vapor phases in the flow varies very much, which affects the observed flow regimes in the heat exchanger channels. At the moment there are not so many experimental data and analytical correlations that would allow to estimate the heat transfer coefficient during the flow of a two-phase mixture flow at low temperatures. The work is devoted to the study of the boiling process of multicomponent working fluids used in refrigeration and cryogenic engineering. The description of the method of determination of heat transfer coefficient during boiling of mixtures in horizontal heated channel is given as well as the design of the experimental stand allowing to make such measurements. This stand is designed on the basis of a refrigeration unit operating on the Joule-Thomson throttle cycle and makes it possible to measure the heat transfer coefficient with a good accuracy. Also, the calculated values of the heat transfer coefficient, obtained with the use of various correlations, are compared with the existing experimental data. Knowing of the heat transfer coefficient will be very useful in the design of heat exchangers for low-temperature units operating on a mixture refrigerant.

A Review on the Fabrication of Polymer-Based Thermoelectric Materials and Fabrication Methods

PubMed Central

Kamarudin, Muhammad Akmal; Sahamir, Shahrir Razey; Datta, Robi Shankar; Long, Bui Duc; Mohd Sabri, Mohd Faizul; Mohd Said, Suhana

2013-01-01

Thermoelectricity, by converting heat energy directly into useable electricity, offers a promising technology to convert heat from solar energy and to recover waste heat from industrial sectors and automobile exhausts. In recent years, most of the efforts have been done on improving the thermoelectric efficiency using different approaches, that is, nanostructuring, doping, molecular rattling, and nanocomposite formation. The applications of thermoelectric polymers at low temperatures, especially conducting polymers, have shown various advantages such as easy and low cost of fabrication, light weight, and flexibility. In this review, we will focus on exploring new types of polymers and the effects of different structures, concentrations, and molecular weight on thermoelectric properties. Various strategies to improve the performance of thermoelectric materials will be discussed. In addition, a discussion on the fabrication of thermoelectric devices, especially suited to polymers, will also be given. Finally, we provide the challenge and the future of thermoelectric polymers, especially thermoelectric hybrid model. PMID:24324378

Three Dimensional Thermal Model of Newberry Volcano, Oregon

DOE Data Explorer

Trenton Cladouhos

2015-01-30

Final results of a 3D finite difference thermal model of Newberry Volcano, Oregon. Model data are formatted as a text file with four data columns (X, Y, Z, T). X and Y coordinates are in UTM (NAD83 Zone 10N), Z is elevation from mean sea level (meters), T is temperature in °C. Model is 40km X 40km X 12.5 km, grid node spacing is 100m in X, Y, and Z directions. A symmetric cylinder shaped magmatic heat source centered on the present day caldera is the modeled heat source. The center of the modeled body is a -1700 m (elevation) and is 600m thick with a radius of 8700m. This is the best fit results from 2D modeling of the west flank of the volcano. The model accounts for temperature dependent thermal properties and latent heat of crystallization. For additional details, assumptions made, data used, and a discussion of the validity of the model see Frone, 2015 (http://search.proquest.com/docview/1717633771).

Photothermal heating and cooling of nanostructures.

PubMed

Crane, Matthew Joseph; Zhou, Xuezhe; Davis, E James; Pauzauskie, Peter

2018-06-11

A vast range of insulating, semiconducting, and metallic nanomaterials have been studied over the past several decades with the aim of understanding how continuous-wave or pulsed laser radiation can influence their chemical functionality and local environment. Many fascinating observations have been made during laser irradiation including, but not limited to, the superheating of solvents, mass-transport-mediated morphology evolution, photodynamic therapy, morphology dependent resonances, and a range of phase transformations. In addition to laser heating, recent experiments have demonstrated the laser cooling of nanoscale materials through the emission of upconverted, anti-Stokes photons by trivalent rare-earth ions. This focus review outlines the analytical modeling of photothermal heat transport with an emphasis on the experimental validation of anti-Stokes laser cooling. This general methodology can be applied to a wide range of photothermal applications, including nanomedicine, photocatalysis, and the synthesis of new materials. The review concludes with an overview of recent advances and future directions for anti-Stokes cooling. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

New simulation of QSO X-ray heating during the Cosmic Dawn

NASA Astrophysics Data System (ADS)

Ross, Hannah E.; Dixon, Keri; Iliev, Ilian; Mellema, Garrelt

2018-05-01

The upcoming radio interferometer Square Kilometre Array is expected to directly detect the redshifted 21-cm signal from the Cosmic Dawn for the first time. In this era temperature fluctuations from X-ray heating of the neutral intergalactic medium can impact this signal dramatically. Previously, in Ross et al. (2017), we presented the first large-volume, 244 h-1 Mpc=349 Mpc a side, fully numerical radiative transfer simulations of X-ray heating. This work is a follow-up where we now also consider QSO-like sources in addition to high mass X-ray binaries. Images of the two cases are clearly distinguishable at SKA1-LOW resolution and have RMS fluctuations above the expected noise. The inclusion of QSOs leads to a dramatic increase in non-Gaussianity of the signal, as measured by the skewness and kurtosis of the 21-cm signal. We conclude that this increased non-Gaussianity is a promising signature of early QSOs.

Heat pipe cooling of power processing magnetics

NASA Technical Reports Server (NTRS)

Hansen, I. G.; Chester, M.

1979-01-01

The constant demand for increased power and reduced mass has raised the internal temperature of conventionally cooled power magnetics toward the upper limit of acceptability. The conflicting demands of electrical isolation, mechanical integrity, and thermal conductivity preclude significant further advancements using conventional approaches. However, the size and mass of multikilowatt power processing systems may be further reduced by the incorporation of heat pipe cooling directly into the power magnetics. Additionally, by maintaining lower more constant temperatures, the life and reliability of the magnetic devices will be improved. A heat pipe cooled transformer and input filter have been developed for the 2.4 kW beam supply of a 30-cm ion thruster system. This development yielded a mass reduction of 40% (1.76 kg) and lower mean winding temperature (20 C lower). While these improvements are significant, preliminary designs predict even greater benefits to be realized at higher power. This paper presents the design details along with the results of thermal vacuum operation and the component performance in a 3 kW breadboard power processor.

Experimental investigation on selective laser melting of 17-4PH stainless steel

NASA Astrophysics Data System (ADS)

Hu, Zhiheng; Zhu, Haihong; Zhang, Hu; Zeng, Xiaoyan

2017-01-01

Selective laser melting (SLM) is an additive manufacturing (AM) technique that uses powders to fabricate 3Dparts directly. The objective of this paper is to perform an experimental investigation of selective laser melted 17-4PH stainless steel. The investigation involved the influence of separate processing parameters on the density, defect, microhardness and the influence of heat-treatment on the mechanical properties. The outcomes of this study show that scan velocity and slice thickness have significant effects on the density and the characteristics of pores of the SLMed parts. The effect of hatch spacing depends on scan velocity. The processing parameters, such as scan velocity, hatch spacing and slice thickness, have effect on microhardness. Compared to the samples with no heat-treatment, the yield strength of the heat-treated sample increases significantly and the elongation decreases due to the transformation of microstructure and the changes in the precipitation strengthening phases. By a combination of changes in composition and precipitation strengthening, microhardness improved.

Graded pitch electromagnetic pump for thin strip metal casting systems

DOEpatents

Kuznetsov, Stephen B.

1986-01-01

A metal strip casing system is provided with an electromagnetic pump which includes a pair of primary blocks having a graded pole pitch, polyphase ac winding and being arranged on opposite sides of a movable heat sink. A nozzle is provided for depositing liquid metal on the heat sink such that the resulting metal strip and heat sink combination is subjected to a longitudinal electromagnetic field which increases in wavelength in the direction of travel of the heat sink, thereby subjecting the metal and heat sink to a longitudinal force having a magnitude which increases in the direction of travel.

Effect of diameter of metal nanowires on pool boiling heat transfer with FC-72

NASA Astrophysics Data System (ADS)

Kumar G., Udaya; S., Suresh; M. R., Thansekhar; Babu P., Dinesh

2017-11-01

Effect of varying diameter of metal nanowires on pool boiling heat transfer performance is presented in this study. Copper nanowires (CuNWs) of four different diameters (∼35 nm, ∼70 nm, ∼130 nm and ∼200 nm) were grown directly on copper specimen using template-based electrodeposition technique. Both critical heat flux (CHF) and boiling heat transfer coefficient (h) were found to be improved in surfaces with nanowires as compared to the bare copper surface. Moreover, both the parameters were found to increase with increasing diameter of the nanowires. The percentage increases observed in CHF for the samples with nanowires were 38.37%, 40.16%, 48.48% and 45.57% whereas the percentage increase in the heat transfer coefficient were 86.36%, 95.45%, 184.1% and 131.82% respectively as compared to the bare copper surface. Important reasons believed for this enhancement were improvement in micron scale cavity density and cavity size which arises as a result of the coagulation and grouping of nanowires during the drying process. In addition to this, superhydrophilic nature, capillary effect, and enhanced bubble dynamics parameters (bubble frequency, bubble departure diameter, and nucleation site density) were found to be the concurring mechanisms responsible for this enhancement in heat transfer performance. Qualitative bubble dynamics analysis was done for the surfaces involved and the visual observations are provided to support the results presented and discussed.

On the use of wearable physiological monitors to assess heat strain during occupational heat stress.

PubMed

Notley, Sean R; Flouris, Andreas D; Kenny, Glen P

2018-05-04

Workers in many industries are required to perform arduous work in high heat stress conditions, which can lead to rapid increases in body temperature that elevate the risk of heat-related illness or even death. Traditionally, effort to mitigate work-related heat injury has been directed to the assessment of environmental heat stress (e.g., wet-bulb globe temperature), rather than the associated physiological strain responses (e.g., heart rate, skin and core temperatures). However, since a workers physiological response to a given heat stress is modified independently by inter-individual factors (e.g., age, sex, chronic disease, others) and intra-individual factors both within (e.g., medication use, fitness, acclimation and hydration state, others) and beyond a workers control (e.g., shift duration, illness, others), it becomes challenging to protect workers on an individual basis from heat-related injury without assessing those physiological responses. Recent advancements in wearable technology have made it possible to monitor one or more physiological indices of heat strain. Nonetheless, information on the utility of the wearable systems available for assessing occupational heat strain is unavailable. This communication is therefore directed at identifying the physiological indices of heat strain that may be quantified in the workplace and evaluating the wearable monitoring systems available for assessing those responses. Finally, emphasis is directed to the barriers associated with implementing these devices to assist in mitigating work-related heat injury. This information is fundamental for protecting worker health and could also be utilized to prevent heat illnesses in vulnerable people during leisure or athletic activities in the heat.

Electron Bernstein Wave Emission Studies on the TJ-II Stellarator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Caughman, John B; Fernandez, A.; Cappa, A.

2009-01-01

Electron Bernstein Wave (EBW) heating is important for high-beta plasma experiments and will be used for heating over-dense plasmas on TJ-II. TJ-II is a medium sized Heliac operating at CIEMAT in Madrid, whose plasmas are created and heated by ECH via two 300 kW gyrotrons at second harmonic X-mode (53.2 GHz), with additional heating provided by two neutral beam injectors. Theoretical work has shown that the most suitable scheme for launching EBWs in TJ-II is O-X-B mode conversion, which has acceptable heating efficiency for central densities above 1.2 x 1019 m-3.[1] A system based on a 28 GHz-100ms diode gyrotronmore » will be used to deliver 300 kW through a corrugated waveguide. The microwave heating beam will be directed and focused by a steering mirror located inside the vacuum vessel. Prior to the heating experiments, measurement of the thermal EBW emission (EBE) from the plasma is being made to help determine the optimum launch angle for EBW mode conversion, and also to provide an indication of the electron temperature evolution in over-dense plasmas. A dual-polarized quad-ridged broadband horn is used to measure the EBW emission and polarization at 28 GHz. Initial measurements indicate that the emission in under-dense plasmas corresponds to oblique electron cyclotron emission (ECE) and then converts to EBE when the plasma becomes over-dense during neutral beam injection.« less

Photo-thermal nanosystems for diseased cell treatment

NASA Astrophysics Data System (ADS)

Raeesi, Vahid

The prevalence of cancer and infectious disease demands for development of more effective treatment technologies. Current standard chemo- and radiotherapy for cancer offer only relative therapeutic efficacy at the cost of significant side-effects. On the other hand, resistance of microbes to current antibiotics has raised serious concern in public health sectors such as hospitals. Thermal therapy is an alternative technique that employs high temperatures to treat diseased cells via direct and indirect heat effects. Owing to its nature, this technique can offer enhanced therapeutic efficacy in local diseased regions via either mono- or combinatorial platforms and very minimal side-effects. However, existing bulk heating systems are limited in providing selective and controlled temperature rise in the desired region at tissue/cellular scales. This compromises the therapeutic efficacy of the treatment and increases the risk of off-target heating in healthy tissues. In this thesis, we propose the use of heat-generating nanoparticles to precisely target heat into small regions and study how they can be applied in cancer and bacteria treatment. Our model nanoparticle system generates heat by light stimulation. Different nanosystems based on this particle are developed and their thermal effects on therapeutic distribution are explored at tumor tissue and cellular scales. In addition, the thermal effect of these nanoparticles is utilized to overcome microbial resistance. By mechanistic understanding of nanoparticle thermal effects at different length scales, this research helps to rationalize proper design and development of heat- generating nanomedicine for cancer and microbial treatments.

Modeling of heat transfer in a vascular tissue-like medium during an interstitial hyperthermia process.

PubMed

Hassanpour, Saeid; Saboonchi, Ahmad

2016-12-01

This paper aims to evaluate the role of small vessels in heat transfer mechanisms of a tissue-like medium during local intensive heating processes, for example, an interstitial hyperthermia treatment. To this purpose, a cylindrical tissue with two co- and counter-current vascular networks and a central heat source is introduced. Next, the energy equations of tissue, supply fluid (arterial blood), and return fluid (venous blood) are derived using porous media approach. Then, a 2D computer code is developed to predict the temperature of blood (fluid phase) and tissue (solid phase) by conventional volume averaging method and a more realistic solution method. In latter method, despite the volume averaging the blood of interconnect capillaries is separated from the arterial and venous blood phases. It is found that in addition to blood perfusion rate, the arrangement of vascular network has considerable effects on the pattern and amount of the achieved temperature. In contrast to counter-current network, the co-current network of vessels leads to considerable asymmetric pattern of temperature contours and relocation of heat affected zone along the blood flow direction. However this relocation can be prevented by changing the site of hyperthermia heat source. The results show that the cooling effect of co-current blood vessels during of interstitial heating is more efficient. Despite much anatomical dissimilarities, these findings can be useful in designing of protocols for hyperthermia cancer treatment of living tissue. Copyright © 2016 Elsevier Ltd. All rights reserved.

Multi-stage flash degaser

DOEpatents

Rapier, Pascal M.

1982-01-01

A multi-stage flash degaser (18) is incorporated in an energy conversion system (10) having a direct-contact, binary-fluid heat exchanger to remove essentially all of the noncondensable gases from geothermal brine ahead of the direct-contact binary-fluid heat exchanger (22) in order that the heat exchanger (22) and a turbine (48) and condenser (32) of the system (10) can operate at optimal efficiency.

SINIS bolometer with a suspended absorber

NASA Astrophysics Data System (ADS)

Tarasov, M.; Edelman, V.; Mahashabde, S.; Fominsky, M.; Lemzyakov, S.; Chekushkin, A.; Yusupov, R.; Winkler, D.; Yurgens, A.

2018-03-01

We have developed a Superconductor-Insulator-Normal Metal-Insulator-Superconductor (SINIS) bolometer with a suspended normal metal bridge. The suspended bridge acts as a bolometric absorber with reduced heat losses to the substrate. Such bolometers were characterized at 100-350 mK bath temperatures and electrical responsivity of over 109 V/W was measured by dc heating the absorber through additional contacts. Suspended bolometers were also integrated in planar twin-slot and log-periodic antennas for operation in the submillimetre-band of radiation. The measured voltage response to radiation at 300 GHz and at 100 mK bath temperature is 3*108 V/W and a current response is 1.1*104 A/W which corresponds to a quantum efficiency of ~15 electrons per photon. An important feature of such suspended bolometers is the thermalization of electrons in the absorber heated by optical radiation, which in turn provides better quantum efficiency. This has been confirmed by comparison of bolometric response to dc and rf heating. We investigate the performance of direct SN traps and NIS traps with a tunnel barrier between the superconductor and normal metal trap. Increasing the volume of superconducting electrode helps to reduce overheating of superconductor. Influence of Andreev reflection and Kapitza resistance, as well as electron-phonon heat conductivity and thermal conductivity of N-wiring are estimated for such SINIS devices.

Preliminary SP-100/Stirling Heat Exchanger Designs

NASA Astrophysics Data System (ADS)

Schmitz, Paul; Tower, Leonard; Dawson, Ronald; Blue, Brain; Dunn, Pat

1994-07-01

Analytic modeling of several heat exchanger concepts to couple the SP-100 nuclear reactor primary lithium loop and the Space Stirling Power Convertor(SSPC)was performed. Four 25 kWe SSPC's are used to produce the required 100 kW of electrical power. This design work focused on the interface between a single SSPC and the primary lithium loop. Manifolding to separate and collect the four channel flow was not modeled. This work modeled two separate types of heat exchanger interfaces (conductive coupling and radiative coupling) to explore their relative advantages and disadvantages. The minimum mass design of the conductively coupled concepts was 18 kg or 0.73 kg/kWe for a single 25 kWe convertor. The minimum mass radiatively coupled concept was 41 kg or 1.64 kg/kWe. The direct conduction heat exchanger provides a lighter weight system because of its ability to operate the Stirling convertor evaporator at higher heat fluxes than those attainable by the radiatively coupled systems. Additionally the conductively coupled concepts had relatively small volumes and provide potentially simpler assembly. Their disadvantages were the tight tolerances and material joining problems associated with this refractory to superalloy interface. The advantages of the radiatively coupled designs were the minimal material interface problems.

Preliminary SP-100/Stirling heat exchanger designs

NASA Astrophysics Data System (ADS)

Schmitz, Paul; Tower, Leonard; Dawson, Ronald; Blue, Brian; Dunn, Pat

1993-12-01

Analytic modeling of several heat exchanger concepts to couple the SP-100 nuclear reactor primary lithium loop and the Space Stirling Power Convertor (SSPC) was performed. Four 25 kWe SSPC's are used to produce the required 100 kW of electrical power. This design work focused on the interface between a single SSPC and the primary lithium loop. Manifolding to separate and collect the four channel flow was not modeled. This work modeled two separate types of heat exchanger interfaces (conductive coupling and radiative coupling) to explore their relative advantages and disadvantages. The minimum mass design of the conductively coupled concepts was 18 kg or 0.73 kg/kWe for a single 25 kWe convertor. The minimum mass radiatively coupled concept was 41 kg or 1.64 kg/kWe. The direct conduction heat exchanger provides a lighter weight system because of its ability to operate the Stirling convertor evaporator at higher heat fluxes than those attainable by the radiatively coupled systems. Additionally the conductively coupled concepts had relatively small volumes and provide potentially simpler assembly. Their disadvantages were the tight tolerances and material joining problems associated with this refractory to superalloy interface. The advantages of the radiatively coupled designs were the minimal material interface problems.

Response of Two Heat Shock Genes to Selection for Knockdown Heat Resistance in Drosophila Melanogaster

PubMed Central

McColl, G.; Hoffmann, A. A.; McKechnie, S. W.

1996-01-01

To identify genes involved in stress resistance and heat hardening, replicate lines of Drosophila melanogaster were selected for increased resistance to knockdown by a 39° heat stress. Two selective regimes were used, one with and one without prior hardening. Mean knockdown times were increased from ~5 min to >20 min after 18 generations. Initial realized heritabilities were as high as 10% for lines selected without hardening, and crosses between lines indicated simple additive gene effects for the selected phenotypes. To survey allelic variation and correlated selection responses in two candidate stress genes, hsr-omega and hsp68, we applied denaturing gradient gel electrophoresis to amplified DNA sequences from small regions of these genes. After eight generations of selection, allele frequencies at both loci showed correlated responses for selection following hardening, but not without hardening. The hardening process itself was associated with a hsp68 frequency change in the opposite direction to that associated with selection that followed hardening. These stress loci are closely linked on chromosome III, and the hardening selection established a disequilibrium, suggesting an epistatic effect on resistance. The data indicate that molecular variation in both hsr-omega and hsp68 contribute to natural heritable variation for hardened heat resistance. PMID:8844150

Infrared thermometry study of nanofluid pool boiling phenomena

PubMed Central

2011-01-01

Infrared thermometry was used to obtain first-of-a-kind, time- and space-resolved data for pool boiling phenomena in water-based nanofluids with diamond and silica nanoparticles at low concentration (<0.1 vol.%). In addition to macroscopic parameters like the average heat transfer coefficient and critical heat flux [CHF] value, more fundamental parameters such as the bubble departure diameter and frequency, growth and wait times, and nucleation site density [NSD] were directly measured for a thin, resistively heated, indium-tin-oxide surface deposited onto a sapphire substrate. Consistent with other nanofluid studies, the nanoparticles caused deterioration in the nucleate boiling heat transfer (by as much as 50%) and an increase in the CHF (by as much as 100%). The bubble departure frequency and NSD were found to be lower in nanofluids compared with water for the same wall superheat. Furthermore, it was found that a porous layer of nanoparticles built up on the heater surface during nucleate boiling, which improved surface wettability compared with the water-boiled surfaces. Using the prevalent nucleate boiling models, it was possible to correlate this improved surface wettability to the experimentally observed reductions in the bubble departure frequency, NSD, and ultimately to the deterioration in the nucleate boiling heat transfer and the CHF enhancement. PMID:21711754

Preliminary SP-100/Stirling heat exchanger designs

NASA Technical Reports Server (NTRS)

Schmitz, Paul; Tower, Leonard; Dawson, Ronald; Blue, Brian; Dunn, Pat

1993-01-01

Analytic modeling of several heat exchanger concepts to couple the SP-100 nuclear reactor primary lithium loop and the Space Stirling Power Convertor (SSPC) was performed. Four 25 kWe SSPC's are used to produce the required 100 kW of electrical power. This design work focused on the interface between a single SSPC and the primary lithium loop. Manifolding to separate and collect the four channel flow was not modeled. This work modeled two separate types of heat exchanger interfaces (conductive coupling and radiative coupling) to explore their relative advantages and disadvantages. The minimum mass design of the conductively coupled concepts was 18 kg or 0.73 kg/kWe for a single 25 kWe convertor. The minimum mass radiatively coupled concept was 41 kg or 1.64 kg/kWe. The direct conduction heat exchanger provides a lighter weight system because of its ability to operate the Stirling convertor evaporator at higher heat fluxes than those attainable by the radiatively coupled systems. Additionally the conductively coupled concepts had relatively small volumes and provide potentially simpler assembly. Their disadvantages were the tight tolerances and material joining problems associated with this refractory to superalloy interface. The advantages of the radiatively coupled designs were the minimal material interface problems.

Design and Performance of a High-Flux Electrospray Ionization Source for Ion Soft-Landing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gunaratne, Kalupathirannehelage Don D.; Prabhakaran, Venkateshkumar; Ibrahim, Yehia M.

2015-01-01

We report the design and evaluation of a new high-intensity electrospray ionization source for ion soft-landing experiments. The source incorporates a dual ion funnel, which enables operation with a higher gas load through an expanded heated inlet into the additional first region of differential pumping. This capability allowed us to examine the effect of the inner diameter (ID) of the heated stainless steel inlet on the total ion current transmitted through the dual funnel interface and, more importantly, the mass-selected ion current delivered to the deposition target. The ion transmission of the dual funnel is similar to the transmission ofmore » the single funnel used in our previous soft landing studies. However, substantially higher ion currents were obtained using larger ID heated inlets and an orthogonal inlet geometry, in which the heated inlet is positioned perpendicular to the direction of ion propagation through the instrument. The highest ion currents were obtained using the orthogonal geometry and a 1.4 mm ID heated inlet. The corresponding stable deposition rate of ~1 μg of mass-selected ions per day will facilitate future studies focused on the controlled deposition of biological molecules on substrates and preparation of materials for studies in catalysis, energy storage, and self-assembly« less

Direct conversion technology

NASA Technical Reports Server (NTRS)

Massier, P. F.; Bankston, C. P.; Fabris, G.; Kirol, L. D.

1988-01-01

The overall objective of the Direct Conversion Technology task is to develop an experimentally verified technology base for promising direct thermal-to-electric energy conversion systems that have potential application for energy conservation in the end-use sectors. This report contains progress of research on the Alkali Metal Thermal-to-Electric Converter (AMTEC), and on the Two-Phase Liquid-Metal MHD Electrical Generator (LMMHD) for the period January 1988 through December 1988. Research on these concepts was initiated during October 1987. In addition, status reviews and assessments are presented for thermomagnetic converter concepts and for thermoelastic converters (Nitinol heat engines). Reports prepared on previous occasions contain discussions on the following other direct conversion concepts: thermoelectric, pyroelectric, thermionic thermophotovoltaic and thermoacoustic; and also, more complete discussions of AMTEC and LMMHD systems. A tabulated summary of the various systems which have been reviewed thus far has been prepared. Some of the important technical research needs are listed and a schematic of each system is shown.

Substrate thermal conductivity controls the ability to manufacture microstructures via laser-induced direct write

DOE PAGES

Tomko, John A.; Olson, David H.; Braun, Jeffrey L.; ...

2018-01-30

In controlling the thermal properties of the surrounding environment, we provide insight into the underlying mechanisms driving the widely used laser direct write method for additive manufacturing. In this study, we find that the onset of silver nitrate reduction for the formation of direct write structures directly corresponds to the calculated steady-state temperature rises associated with both continuous wave and high-repetition rate, ultrafast pulsed laser systems. Furthermore, varying the geometry of the heat affected zone, which is controllable based on in-plane thermal diffusion in the substrate, and laser power, allows for control of the written geometries without any prior substratemore » preparation. In conclusion, these findings allow for the advance of rapid manufacturing of micro- and nanoscale structures with minimal material constraints through consideration of the laser-controllable thermal transport in ionic liquid/substrate media.« less

Substrate thermal conductivity controls the ability to manufacture microstructures via laser-induced direct write

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tomko, John A.; Olson, David H.; Braun, Jeffrey L.

In controlling the thermal properties of the surrounding environment, we provide insight into the underlying mechanisms driving the widely used laser direct write method for additive manufacturing. In this study, we find that the onset of silver nitrate reduction for the formation of direct write structures directly corresponds to the calculated steady-state temperature rises associated with both continuous wave and high-repetition rate, ultrafast pulsed laser systems. Furthermore, varying the geometry of the heat affected zone, which is controllable based on in-plane thermal diffusion in the substrate, and laser power, allows for control of the written geometries without any prior substratemore » preparation. In conclusion, these findings allow for the advance of rapid manufacturing of micro- and nanoscale structures with minimal material constraints through consideration of the laser-controllable thermal transport in ionic liquid/substrate media.« less

Direct Contact Heat Exchange Interfacial Phenomena for Liquid Metal Reactors: Part II - Void Fraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abdulla, S.; Liu, X.; Anderson, M.H.

One concept being considered for steam generation in innovative nuclear reactor applications, involves water coming into direct contact with a circulating molten metal. The vigorous agitation of the two fluids, the direct liquid-liquid contact and the consequent large interfacial area can give rise to large heat transfer coefficients and rapid steam generation. For an optimum design of such direct contact heat exchange and vaporization systems, detailed knowledge is necessary of the various flow regimes, interfacial transport phenomena, heat transfer and operational stability. In order to investigate the interfacial transport phenomena, heat transfer and operational stability of direct liquid-liquid contact, amore » series of experiments are being performed in a 1-d test facility at Argonne National Laboratory and a 2-d experimental facility at UW-Madison. Each of the experimental facilities primarily consist of a liquid-metal melt chamber, heated test section (10 cm diameter tube for 1-d facility and 10 cm 50 cm rectangle for 2-d facility), water injection system and steam suppression tank. This paper is part II which, primarily addresses results and analysis of a set of preliminary experiments and void fraction measurements conducted in the 2-d facility at UW-Madison, part I deals with the heat transfer in the 1-d test facility at Argonne National Laboratory. A real-time high energy X-ray imaging system was developed and utilized to visualize the multiphase flow and measure line-average local void fractions, time-dependent void fraction distribution as well as estimates of the vapor bubble sizes and velocities. These measurements allowed us to determine the volumetric heat transfer coefficient and gain insight into the local heat transfer mechanisms. In this study, the images were captured at frame rates of 100 fps with spatial resolution of about 7 mm with a full-field view of a 15 cm square and five different positions along the test section height. The full-field average void fraction increases rapidly to about 15% in these preliminary tests, with the apparent boiling length of less than 20 cm. The volumetric heat transfer coefficient between the liquid metal and water are compared to the CRIEPI data, the only prior data for direct contact heat exchange for these liquid metal/water systems. (authors)« less

Coupled Chiral Structure in Graphene-Based Film for Ultrahigh Thermal Conductivity in Both In-Plane and Through-Plane Directions.

PubMed

Meng, Xin; Pan, Hui; Zhu, Chengling; Chen, Zhixin; Lu, Tao; Xu, Da; Li, Yao; Zhu, Shenmin

2018-06-21

The development of high-performance thermal management materials to dissipate excessive heat both in plane and through plane is of special interest to maintain efficient operation and prolong the life of electronic devices. Herein, we designed and constructed a graphene-based composite film, which contains chiral liquid crystals (cellulose nanocrystals, CNCs) inside graphene oxide (GO). The composite film was prepared by annealing and compacting of self-assembled GO-CNC, which contains chiral smectic liquid crystal structures. The helical arranged nanorods of carbonized CNC act as in-plane connections, which bridge neighboring graphene sheets. More interestingly, the chiral structures also act as through-plane connections, which bridge the upper and lower graphene layers. As a result, the graphene-based composite film shows extraordinary thermal conductivity, in both in-plane (1820.4 W m -1 K -1 ) and through-plane (4.596 W m -1 K -1 ) directions. As a thermal management material, the heat dissipation and transportation behaviors of the composite film were investigated using a self-heating system and the results showed that the real-time temperature of the heater covered with the film was 44.5 °C lower than a naked heater. The prepared film shows a much higher efficiency of heat transportation than the commonly used thermal conductive Cu foil. Additionally, this graphene-based composite film exhibits excellent mechanical strength of 31.6 MPa and an electrical conductivity of 667.4 S cm -1 . The strategy reported here may open a new avenue to the development of high-performance thermal management films.

5-HT modulation of pain perception in humans.

PubMed

Martin, Sarah L; Power, Andrea; Boyle, Yvonne; Anderson, Ian M; Silverdale, Monty A; Jones, Anthony K P

2017-10-01

Although there is clear evidence for the serotonergic regulation of descending control of pain in animals, little direct evidence exists in humans. The majority of our knowledge comes from the use of serotonin (5-HT)-modulating antidepressants as analgesics in the clinical management of chronic pain. Here, we have used an acute tryptophan depletion (ATD) to manipulate 5-HT function and examine its effects of ATD on heat pain threshold and tolerance, attentional manipulation of nociceptive processing and mood in human volunteers. Fifteen healthy participants received both ATD and balanced amino acid (BAL) drinks on two separate sessions in a double-blind cross-over design. Pain threshold and tolerance were determined 4 h post-drink via a heat thermode. Additional attention, distraction and temperature discrimination paradigms were completed using a laser-induced heat pain stimulus. Mood was assessed prior and throughout each session. Our investigation reported that the ATD lowered plasma TRP levels by 65.05 ± 7.29% and significantly reduced pain threshold and tolerance in response to the heat thermode. There was a direct correlation between the reduction in total plasma TRP levels and reduction in thermode temperature. In contrast, ATD showed no effect on laser-induced pain nor significant impact of the distraction-induced analgesia on pain perception but did reduce performance of the painful temperature discrimination task. Importantly, all findings were independent of any effects of ATD on mood. As far as we are aware, it is the first demonstration of 5-HT effects on pain perception which are not confounded by mood changes.

Multi Laser Pulse Investigation of the DEAS Concept in Hypersonic Flow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Minucci, M.A.S.; Toro, P.G.P.; Oliveira, A.C.

2004-03-30

The present paper presents recent experimental results on the Laser-Supported Directed Energy 'Air Spike' - DEAS in hypersonic flow achieved by the Laboratory of Aerothermodynamics and Hypersonics - LAH, Brazil. Two CO2 TEA lasers, sharing the same optical cavity, have been used in conjunction with the IEAv 0.3m Hypersonic Shock Tunnel - HST to demonstrate the Laser-Supported DEAS concept. A single and double laser pulse, generated during the tunnel useful test time, were focused through a NaCl lens upstream of a Double Apollo Disc model fitted with seven piezoelectric pressure transducers and six platinum thin film heat transfer gauges. Themore » objective being to corroborate previous results as well as to obtain additional pressure and heat flux distributions information when two laser pulses are used.« less

Update on Geothermal Direct-Use Installations in the United States

DOE Data Explorer

Beckers, Koenraad F.; Snyder, Diana M.; Young, Katherine R.

2017-03-02

An updated database of geothermal direct-use systems in the U.S. has been compiled and analyzed, building upon the Oregon Institute of Technology (OIT) Geo-Heat Center direct-use database. Types of direct-use applications examined include hot springs resorts and pools, aquaculture farms, greenhouses, and district heating systems, among others; power-generating facilities and ground-source heat pumps were excluded. Where possible, the current operation status, open and close dates, well data, and other technical data were obtained for each entry. The database contains 545 installations, of which 407 are open, 108 are closed, and 30 have an unknown status. A report is also included which details and analyzes current geothermal direct-use installations and barriers to further implementation.

UF.sub.6 -Recovery process utilizing desublimation

DOEpatents

Eby, Robert S.; Stephenson, Michael J.; Andrews, Deborah H.; Hamilton, Thomas H.

1985-01-01

The invention is a UF.sub.6 -recovery process of the kind in which a stream of substantially pure gaseous UF.sub.6 is directed through an externally chilled desublimer to convert the UF.sub.6 directly to an annular solid ring adhering to the interior wall of the desublimer. After accumulation of a desired amount of solid UF.sub.6, the desublimer is heated to liquefy the solid. Subsequently, the liquid is recovered from the desublimer. It has been found that during the heating operation the desublimer is subjected to excessive mechanical stresses. In addition, it has been found that the incorporation of a very small percentage of relatively noncondensable, nonreactive gas (e.g., nitrogen) in the UF.sub.6 input to the desublimer effects significant decreases in the stresses generated during the subsequent melting operation. This modification to the process provides valuable advantages in terms of reduced hazard, lower operating costs for the desublimer, and increased service life for the desublimer and its auxiliaries. The new process is especially suitable for the recovery of enriched UF.sub.6 from high-speed UF.sub.6 gas-centrifuge cascades.

Evaluation of high temperature capacitor dielectrics

NASA Astrophysics Data System (ADS)

Hammoud, Ahmad N.; Myers, Ira T.

Experiments were carried out to evaluate four candidate materials for high temperature capacitor dielectric applications. The materials investigated were polybenzimidazole polymer and three aramid papers: Voltex 450, Nomex 410, and Nomex M 418, an aramid paper containing 50 percent mica. The samples were heat treated for six hours at 60 C and the direct current and 60 Hz alternating current breakdown voltages of both dry and impregnated samples were obtained in a temperature range of 20 to 250 C. The samples were also characterized in terms of their dielectric constant, dielectric loss, and conductivity over this temperature range with an electrical stress of 60 Hz, 50 V/mil present. Additional measurements are underway to determine the volume resistivity, thermal shrinkage, and weight loss of the materials. Preliminary data indicate that the heat treatment of the films slightly improves the dielectric properties with no influence on their breakdown behavior. Impregnation of the samples leads to significant increases in both alternating and direct current breakdown strength. The results are discussed and conclusions made concerning their suitability as high temperature capacitor dielectrics.

Tuning of optical properties of CdS nanoparticles synthesized in a glass matrix

NASA Astrophysics Data System (ADS)

Popov, Ivan D.; Kuznetsova, Yulia V.; Rempel, Svetlana V.; Rempel, Andrey A.

2018-03-01

Attempts were made to provide the data concerning directed synthesis of semiconductor nanoparticles in a dielectric silica-based glass matrix. These attempts involve finding out the connections between the structure, size of CdS nanoparticles, and optical properties of the nanocomposites produced. High-resolution focused ion beam scanning electron microscopy images of CdS nanoparticles incorporated in glass and SAXS results confirm the formation of uniformly distributed spherical CdS nanoparticles with an average diameter of about 6.2 nm. UV-Vis measurements show that CdS composites possess a direct bandgap wider than 2.45 eV depending on the heat treatment conditions; thus, heat treatment can be used to control nanoparticle size in each selected composite. The emission spectra showed a maximum at about 603 nm and a red shift of about 100 nm with increasing annealing temperature that is associated with the presence of defect states in the nanoparticles. In addition, semiconductor phase concentration in the glass matrix was found by using optical absorption data for the first time, which allows understanding the effect of nanocomposite structure on luminescence properties.

Evaluation of high temperature capacitor dielectrics

NASA Technical Reports Server (NTRS)

Hammoud, Ahmad N.; Myers, Ira T.

1992-01-01

Experiments were carried out to evaluate four candidate materials for high temperature capacitor dielectric applications. The materials investigated were polybenzimidazole polymer and three aramid papers: Voltex 450, Nomex 410, and Nomex M 418, an aramid paper containing 50 percent mica. The samples were heat treated for six hours at 60 C and the direct current and 60 Hz alternating current breakdown voltages of both dry and impregnated samples were obtained in a temperature range of 20 to 250 C. The samples were also characterized in terms of their dielectric constant, dielectric loss, and conductivity over this temperature range with an electrical stress of 60 Hz, 50 V/mil present. Additional measurements are underway to determine the volume resistivity, thermal shrinkage, and weight loss of the materials. Preliminary data indicate that the heat treatment of the films slightly improves the dielectric properties with no influence on their breakdown behavior. Impregnation of the samples leads to significant increases in both alternating and direct current breakdown strength. The results are discussed and conclusions made concerning their suitability as high temperature capacitor dielectrics.

UF/sub 6/-recovery process utilizing desublimation

DOEpatents

Eby, R.S.; Stephenson, M.J.; Andrews, D.H.; Hamilton, T.H.

1983-12-21

The invention is a UF/sub 6/-recovery process of the kind in which a stream of substantially pure gaseous UF/sub 6/ is directed through an externally chilled desublimer to convert the UF/sub 6/ directly to an annular solid ring adhering to the interior wall of the desublimer. After accumulation of a desired amount of solid UF/sub 6/, the desublimer is heated to liquefy the solid. Subsequently, the liquid is recovered from the desublimer. It has been found that during the heating operation the desublimer is subjected to excessive mechanical stresses. In addition, it has been found that the incorporation of a very small percentage of relatively noncondensable, nonreactive gas (e.g., nitrogen) in the UF/sub 6/ input to the desublimer effects significant decreases in the stresses generated during the subsequent melting operation. This modification to the process provides valuable advantages in terms of reduced hazard, lower operating costs for the desublimer, and increased service life for the desublimer and its auxiliaries. The new process is especially suitable for the recovery of enriched UF/sub 6/ from high-speed UF/sub 6/ gas-centrifuge cascades.

Low-Cost Radiator for Fission Power Thermal Control

NASA Technical Reports Server (NTRS)

Maxwell, Taylor; Tarau, Calin; Anderson, William; Hartenstine, John; Stern, Theodore; Walmsley, Nicholas; Briggs, Maxwell

2014-01-01

NASA Glenn Research Center (GRC) is developing fission power system technology for future Lunar surface power applications. The systems are envisioned in the 10 to 100kW(sub e) range and have an anticipated design life of 8 to 15 years with no maintenance. NASA GRC is currently setting up a 55 kW(sub e) non-nuclear system ground test in thermal-vacuum to validate technologies required to transfer reactor heat, convert the heat into electricity, reject waste heat, process the electrical output, and demonstrate overall system performance. Reducing the radiator mass, size, and cost is essential to the success of the program. To meet these goals, Advanced Cooling Technologies, Inc. (ACT) and Vanguard Space Technologies, Inc. (VST) are developing a single facesheet radiator with heat pipes directly bonded to the facesheet. The facesheet material is a graphite fiber reinforced composite (GFRC) and the heat pipes are titanium/water. By directly bonding a single facesheet to the heat pipes, several heavy and expensive components can be eliminated from the traditional radiator design such as, POC(TradeMark) foam saddles, aluminum honeycomb, and a second facesheet. A two-heat pipe radiator prototype, based on the single facesheet direct-bond concept, was fabricated and tested to verify the ability of the direct-bond joint to withstand coefficient of thermal expansion (CTE) induced stresses during thermal cycling. The thermal gradients along the bonds were measured before and after thermal cycle tests to determine if the performance degraded. Overall, the results indicated that the initial uniformity of the adhesive was poor along one of the heat pipes. However, both direct bond joints showed no measureable amount of degradation after being thermally cycled at both moderate and aggressive conditions.

Direct fired absorption machine flue gas recuperator

DOEpatents

Reimann, Robert C.; Root, Richard A.

1985-01-01

A recuperator which recovers heat from a gas, generally the combustion gas of a direct-fired generator of an absorption machine. The recuperator includes a housing with liquid flowing therethrough, the liquid being in direct contact with the combustion gas for increasing the effectiveness of the heat transfer between the gas and the liquid.

Tailoring magnetostriction with various directions for directional solidification Fe82Ga15Al3 alloy by magnetic field heat treatment

NASA Astrophysics Data System (ADS)

Li, Xiaolong; Bao, Xiaoqian; Liu, Yangyang; Yu, Linhua; Li, Jiheng; Gao, Xuexu

2017-10-01

The magnetostriction of the Fe82Ga15Al3 alloy, along the length and width, can be tailored by applying a magnetic field heat treatment. In this work, the Fe82Ga15Al3 sheet was cut from the directional solidified Fe82Ga15Al3 alloy with the ⟨100⟩ preferred orientation and was annealed at 720 °C for 30 min under a magnetic field of 800 Oe along the length direction with a heating and cooling rate of 100 °C/min. The magnetostrictive properties along the length and width directions were modified to λ// = 7 ppm and λ⊥ = -210 ppm from λ// = 210 ppm and λ⊥ = -10 ppm for the initial sample prior to the magnetic field heat treatment. The cellular-like magnetic domain structure was composed of parallel 180° stripe domains and vertical 90° domains observed using a magnetic-force microscope. The change in magnetostriction along parallel and perpendicular directions was mainly resulted from the rotation of the magnetic domain units.

Development of high temperature calorimeter: heat capacity measurement by direct heating pulse calorimetry

NASA Astrophysics Data System (ADS)

Arita, Yuji; Suzuki, Keisuke; Matsui, Tsuneo

2005-02-01

The temperature limit for heat capacity measurements with the direct heating pulse calorimeter has been increased up to 2000 K by means of the combination of an optical pyrometer to detect the relative temperature change with tungsten rhenium thermocouples to determine absolute temperatures. With this improved calorimeter the heat capacities were measured up to 1950 K, for SiC and B4C, and 2000 K for graphite. The heat capacity values obtained in this study were in good agreement, within the error of ±5%, with those previous values calculated from the enthalpy data by drop method. The electrical conductivities of SiC, B4C and graphite were also simultaneously determined from the inducted voltage and the current for heat capacity measurement.

Air-Lubricated Thermal Processor For Dry Silver Film

NASA Astrophysics Data System (ADS)

Siryj, B. W.

1980-09-01

Since dry silver film is processed by heat, it may be viewed on a light table only seconds after exposure. On the other hand, wet films require both bulky chemicals and substantial time before an image can be analyzed. Processing of dry silver film, although simple in concept, is not so simple when reduced to practice. The main concern is the effect of film temperature gradients on uniformity of optical film density. RCA has developed two thermal processors, different in implementation but based on the same philosophy. Pressurized air is directed to both sides of the film to support the film and to conduct the heat to the film. Porous graphite is used as the medium through which heat and air are introduced. The initial thermal processor was designed to process 9.5-inch-wide film moving at speeds ranging from 0.0034 to 0.008 inch per second. The processor configuration was curved to match the plane generated by the laser recording beam. The second thermal processor was configured to process 5-inch-wide film moving at a continuously variable rate ranging from 0.15 to 3.5 inches per second. Due to field flattening optics used in this laser recorder, the required film processing area was plane. In addition, this processor was sectioned in the direction of film motion, giving the processor the capability of varying both temperature and effective processing area.

Design of a Resistively Heated Thermal Hydraulic Simulator for Nuclear Rocket Reactor Cores

NASA Technical Reports Server (NTRS)

Litchford, Ron J.; Foote, John P.; Ramachandran, Narayanan; Wang, Ten-See; Anghaie, Samim

2007-01-01

A preliminary design study is presented for a non-nuclear test facility which uses ohmic heating to replicate the thermal hydraulic characteristics of solid core nuclear reactor fuel element passages. The basis for this testing capability is a recently commissioned nuclear thermal rocket environments simulator, which uses a high-power, multi-gas, wall-stabilized constricted arc-heater to produce high-temperature pressurized hydrogen flows representative of reactor core environments, excepting radiation effects. Initially, the baseline test fixture for this non-nuclear environments simulator was configured for long duration hot hydrogen exposure of small cylindrical material specimens as a low cost means of evaluating material compatibility. It became evident, however, that additional functionality enhancements were needed to permit a critical examination of thermal hydraulic effects in fuel element passages. Thus, a design configuration was conceived whereby a short tubular material specimen, representing a fuel element passage segment, is surrounded by a backside resistive tungsten heater element and mounted within a self-contained module that inserts directly into the baseline test fixture assembly. With this configuration, it becomes possible to create an inward directed radial thermal gradient within the tubular material specimen such that the wall-to-gas heat flux characteristics of a typical fuel element passage are effectively simulated. The results of a preliminary engineering study for this innovative concept are fully summarized, including high-fidelity multi-physics thermal hydraulic simulations and detailed design features.

Magnetic nanoparticle hyperthermia as an adjuvant cancer therapy with chemotherapy

NASA Astrophysics Data System (ADS)

Petryk, Alicia Ailie

Magnetic nanoparticle hyperthermia (mNPH) is an emerging cancer therapy which has shown to be most effective when applied in the adjuvant setting with chemotherapy, radiation or surgery. Although mNPH employs heat as a primary therapeutic modality, conventional heat may not be the only cytotoxic effect. As such, my studies have focused on the mechanism and use of mNPH alone and in conjunction with cisplatinum chemotherapy in murine breast cancer cells and a related in vivo model. MNPH was compared to conventional microwave tumor heating, with results suggesting that mNPH (mNP directly injected into the tumor and immediately activated) and 915 MHz microwave hyperthermia, at the same thermal dose, result in similar tumor regrowth delay kinetics. However, mNPH shows significantly less peri-tumor normal tissue damage. MNPH combined with cisplatinum also demonstrated significant improvements in regrowth delay over either modality applied as a monotherapy. Additional studies demonstrated that a relatively short tumor incubation time prior to AMF exposure (less than 10 minutes) as compared to a 4-hour incubation time, resulted in faster heating rates, but similar regrowth delays when treated to the same thermal dose. The reduction of heating rate correlated well with the observed reduction in mNP concentration in the tumor observed with 4 hour incubation. The ability to effectively deliver cytotoxic mNPs to metastatic tumors is the hope and goal of systemic mNP therapy. However, delivering relevant levels of mNP is proving to be a formidable challenge. To address this issue, I assessed the ability of cisplatinum to simultaneously treat a tumor and improve the uptake of systemically delivered mNPs. Following a cisplatinum pretreatment, systemic mNPs uptake was increased by 3.1 X, in implanted murine breast tumors. Additional in vitro studies showed the necessity of a specific mNP/ Fe architecture and spatial relation for heat-based cytotoxicity in cultured cells.

Investigation of internally finned LED heat sinks

NASA Astrophysics Data System (ADS)

Li, Bin; Xiong, Lun; Lai, Chuan; Tang, Yumei

2018-03-01

A novel heat sink is proposed, which is composed of a perforated cylinder and internally arranged fins. Numerical studies are performed on the natural convection heat transfer from internally finned heat sinks; experimental studies are carried out to validate the numerical results. To compare the thermal performances of internally finned heat sinks and externally finned heat sinks, the effects of the overall diameter, overall height, and installation direction on maximum temperature, air flow and heat transfer coefficient are investigated. The results demonstrate that internally finned heat sinks show better thermal performance than externally finned heat sinks; the maximum temperature of internally finned heat sinks decreases by up to 20% compared with the externally finned heat sinks. The existence of a perforated cylinder and the installation direction of the heat sink affect the thermal performance significantly; it is shown that the heat transfer coefficient of the heat sink with the perforated cylinder is improved greater than that with the imperforated cylinder by up to 34%, while reducing the mass of the heat sink by up to 13%. Project supported by the Scientific Research Fund of Sichuan Provincial Education Department (No. 18ZB0516) and the Sichuan University of Arts and Science (No. 2016KZ009Y).

Heat pump system with selective space cooling

DOEpatents

Pendergrass, J.C.

1997-05-13

A reversible heat pump provides multiple heating and cooling modes and includes a compressor, an evaporator and heat exchanger all interconnected and charged with refrigerant fluid. The heat exchanger includes tanks connected in series to the water supply and a condenser feed line with heat transfer sections connected in counterflow relationship. The heat pump has an accumulator and suction line for the refrigerant fluid upstream of the compressor. Sub-cool transfer tubes associated with the accumulator/suction line reclaim a portion of the heat from the heat exchanger. A reversing valve switches between heating/cooling modes. A first bypass is operative to direct the refrigerant fluid around the sub-cool transfer tubes in the space cooling only mode and during which an expansion valve is utilized upstream of the evaporator/indoor coil. A second bypass is provided around the expansion valve. A programmable microprocessor activates the first bypass in the cooling only mode and deactivates the second bypass, and vice-versa in the multiple heating modes for said heat exchanger. In the heating modes, the evaporator may include an auxiliary outdoor coil for direct supplemental heat dissipation into ambient air. In the multiple heating modes, the condensed refrigerant fluid is regulated by a flow control valve. 4 figs.

Heat pump system with selective space cooling

DOEpatents

Pendergrass, Joseph C.

1997-01-01

A reversible heat pump provides multiple heating and cooling modes and includes a compressor, an evaporator and heat exchanger all interconnected and charged with refrigerant fluid. The heat exchanger includes tanks connected in series to the water supply and a condenser feed line with heat transfer sections connected in counterflow relationship. The heat pump has an accumulator and suction line for the refrigerant fluid upstream of the compressor. Sub-cool transfer tubes associated with the accumulator/suction line reclaim a portion of the heat from the heat exchanger. A reversing valve switches between heating/cooling modes. A first bypass is operative to direct the refrigerant fluid around the sub-cool transfer tubes in the space cooling only mode and during which an expansion valve is utilized upstream of the evaporator/indoor coil. A second bypass is provided around the expansion valve. A programmable microprocessor activates the first bypass in the cooling only mode and deactivates the second bypass, and vice-versa in the multiple heating modes for said heat exchanger. In the heating modes, the evaporator may include an auxiliary outdoor coil for direct supplemental heat dissipation into ambient air. In the multiple heating modes, the condensed refrigerant fluid is regulated by a flow control valve.

40 CFR 97.76 - Additional requirements to provide heat input data.

Code of Federal Regulations, 2010 CFR

2010-07-01

... heat input data. 97.76 Section 97.76 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Monitoring and Reporting § 97.76 Additional requirements to provide heat input data. The owner or operator of... a flow system shall also monitor and report heat input rate at the unit level using the procedures...

40 CFR 97.76 - Additional requirements to provide heat input data.

Code of Federal Regulations, 2011 CFR

2011-07-01

... heat input data. 97.76 Section 97.76 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Monitoring and Reporting § 97.76 Additional requirements to provide heat input data. The owner or operator of... a flow system shall also monitor and report heat input rate at the unit level using the procedures...

40 CFR 97.76 - Additional requirements to provide heat input data.

Code of Federal Regulations, 2013 CFR

2013-07-01

... heat input data. 97.76 Section 97.76 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Monitoring and Reporting § 97.76 Additional requirements to provide heat input data. The owner or operator of... a flow system shall also monitor and report heat input rate at the unit level using the procedures...

40 CFR 97.76 - Additional requirements to provide heat input data.

Code of Federal Regulations, 2014 CFR

2014-07-01

... heat input data. 97.76 Section 97.76 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Monitoring and Reporting § 97.76 Additional requirements to provide heat input data. The owner or operator of... a flow system shall also monitor and report heat input rate at the unit level using the procedures...

40 CFR 97.76 - Additional requirements to provide heat input data.

Code of Federal Regulations, 2012 CFR

2012-07-01

... heat input data. 97.76 Section 97.76 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Monitoring and Reporting § 97.76 Additional requirements to provide heat input data. The owner or operator of... a flow system shall also monitor and report heat input rate at the unit level using the procedures...

AUTOMATIC AIR BURST DIRECTION FINDER

DOEpatents

Allard, G.A.

1952-01-31

This patent application describes an atomic explosion direction indicator comprising a geometric heat-scorchable indicating surface symmetrical about an axis, elevation and azimuth markings on the heat scorchable surface, and an indicating rod at the axis of said surface arranged to cast a shadow hereon, whereby heat from an atomic explosion will scorch a pattern on said surface indicative of the azimuth and elevation of said explosion.

Heat-resistant DNA tile arrays constructed by template-directed photoligation through 5-carboxyvinyl-2′-deoxyuridine

PubMed Central

Tagawa, Miho; Shohda, Koh-ichiroh; Fujimoto, Kenzo; Sugawara, Tadashi; Suyama, Akira

2007-01-01

Template-directed DNA photoligation has been applied to a method to construct heat-resistant two-dimensional (2D) DNA arrays that can work as scaffolds in bottom-up assembly of functional biomolecules and nano-electronic components. DNA double-crossover AB-staggered (DXAB) tiles were covalently connected by enzyme-free template-directed photoligation, which enables a specific ligation reaction in an extremely tight space and under buffer conditions where no enzymes work efficiently. DNA nanostructures created by self-assembly of the DXAB tiles before and after photoligation have been visualized by high-resolution, tapping mode atomic force microscopy in buffer. The improvement of the heat tolerance of 2D DNA arrays was confirmed by heating and visualizing the DNA nanostructures. The heat-resistant DNA arrays may expand the potential of DNA as functional materials in biotechnology and nanotechnology. PMID:17982178

Stability analysis of direct contact heat exchangers subject to system perturbations. Final report, Task 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jacobs, H.R.

1985-01-01

This report includes a project summary, copies of two papers resulting from the work and the Ph.D. Dissertation of Dr. Mehdi Golafshani entitled, ''Stability of a Direct Contact Heat Exchanger''. Specifically, the work deals with the operational stability of a spray column type heat exchanger subject to disturbances typical of those which can occur for geothermal applications. A computer program was developed to solve the one-dimensional transient two-phase flow problem and it was applied to the design of a spray column. The operation and design of the East Mesa 500kW/sub e/ direct contactor was assessed. It is shown that themore » heat transfer is governed by the internal resistance of the dispersed phase. In fact, the performance is well-represented by diffusion of heat within the drops. 5 refs.« less

Electronic cooling using thermoelectric devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zebarjadi, M., E-mail: m.zebarjadi@rutgers.edu; Institute of Advanced Materials, Devices, and Nanotechnology, Rutgers University, Piscataway, New Jersey 08854

2015-05-18

Thermoelectric coolers or Peltier coolers are used to pump heat in the opposite direction of the natural heat flux. These coolers have also been proposed for electronic cooling, wherein the aim is to pump heat in the natural heat flux direction and from hot spots to the colder ambient temperature. In this manuscript, we show that for such applications, one needs to use thermoelectric materials with large thermal conductivity and large power factor, instead of the traditionally used high ZT thermoelectric materials. We further show that with the known thermoelectric materials, the active cooling cannot compete with passive cooling, andmore » one needs to explore a new set of materials to provide a cooling solution better than a regular copper heat sink. We propose a set of materials and directions for exploring possible materials candidates suitable for electronic cooling. Finally, to achieve maximum cooling, we propose to use thermoelectric elements as fins attached to copper blocks.« less

Field evaluation and assessment of thermal energy storage for residential space heating

NASA Astrophysics Data System (ADS)

Hersh, H. N.

1982-02-01

A data base was developed based on two heating seasons and 45 test and 30 control homes in Maine and Vermont. Based on first analysis of monitored temperatures and electrical energy used for space heating, fuel bills and reports of users and utilities, the technical performance of TES ceramic and hydronic systems is deemed to be technically satisfactory and there is a high degree of customer acceptance and positive attitudes towards TES. Analysis of house data shows a high degree of variability in electric heat energy demand for a given degree-day. An analysis is underway to investigate relative differences in the efficiency of electricity utilization of storage and direct heating devices. The much higher price of storge systems relative to direct systems is an impediment to market penetration. A changing picture of rate structures may encourage direct systems at the expense of storage systems.

Stepping Up: Burden Sharing by NATO’s Newest Members

DTIC Science & Technology

2014-11-01

heat and does not lead only to a new sense of frustration and futility. This would be the worst outcome for the Alli- ance. But the great merit of...today. While the norms have remained constant, changes in the post-Cold War balance of power have placed ad- ditional stress on burden sharing...its more than 65 years of existence, many directly related to burden sharing concerns.5 Yet, the fall of the Soviet Union placed additional stress on

Dynamic Behavior of Nano-Sized Particles in Novel Energetic Materials for Space Propulsion

DTIC Science & Technology

2009-08-11

independent of direction); then I(rw,s) = Jwir^/ir, n • s > 0, (8) where Jw = enlb + pH (9) is the surface radiosity and the subscript w denotes a...of the surface radiosity yields G + 2q„ =4JW. (28) In addition to this relation, we require that the normal radiative heat flux is the sum of the...incident and reflected ( radiosity ) contributions: qn = Jw - H. (29) The incident radiation is eliminated in favor of the radiosity using (9) and the

Hybrid solar central receiver for combined cycle power plant

DOEpatents

Bharathan, D.; Bohn, M.S.; Williams, T.A.

1995-05-23

A hybrid combined cycle power plant is described including a solar central receiver for receiving solar radiation and converting it to thermal energy. The power plant includes a molten salt heat transfer medium for transferring the thermal energy to an air heater. The air heater uses the thermal energy to preheat the air from the compressor of the gas cycle. The exhaust gases from the gas cycle are directed to a steam turbine for additional energy production. 1 figure.

A new magnesium alloy system: TEXAS

NASA Astrophysics Data System (ADS)

Wiese, Björn; Mendis, Chamini; Blawert, Carsten; Nyberg, Eric; Kainer, Karl Ulrich; Hort, Norbert

A new TEXAS alloy system (Mg-Sn-Nd-Ca-Al-Si) is presented in order to extend the range of applications for magnesium alloys. The alloy has been produced by permanent mould direct chill casting, a process that provides a homogenous distribution of alloying elements throughout the entire casting. This work presents microstructural features and a new Mg-Sn-Ca phase with the morphology of hexagonal platelets. Additionally mechanical properties and the corrosion behaviour of TEXAS alloys are presented in as cast and heat treated conditions.

Additive/Subtractive Manufacturing Research and Development in Europe

DTIC Science & Technology

2004-12-01

electronic gates and switches. The idea is to attach a gold nanoparticle to a redox gate (molecule) that undergoes reduction and oxidation reactions...This is used to synthesize mixed metal oxides such as CeO2, Ce:Zr, ZrO2, and Pr:Ce and produce them in nanoparticle form. The fourth project that was...on glass. Laser patterning is followed by heating to diffuse the oxide into the glass. MMSC has used the direct-write of conductors on polymer

Laser processing for manufacturing nanocarbon materials

NASA Astrophysics Data System (ADS)

Van, Hai Hoang

CNTs have been considered as the excellent candidate to revolutionize a broad range of applications. There have been many method developed to manipulate the chemistry and the structure of CNTs. Laser with non-contact treatment capability exhibits many processing advantages, including solid-state treatment, extremely fast processing rate, and high processing resolution. In addition, the outstanding monochromatic, coherent, and directional beam generates the powerful energy absorption and the resultant extreme processing conditions. In my research, a unique laser scanning method was developed to process CNTs, controlling the oxidation and the graphitization. The achieved controllability of this method was applied to address the important issues of the current CNT processing methods for three applications. The controllable oxidation of CNTs by laser scanning method was applied to cut CNT films to produce high-performance cathodes for FE devices. The production method includes two important self-developed techniques to produce the cold cathodes: the production of highly oriented and uniformly distributed CNT sheets and the precise laser trimming process. Laser cutting is the unique method to produce the cathodes with remarkable features, including ultrathin freestanding structure (~200 nm), greatly high aspect ratio, hybrid CNT-GNR emitter arrays, even emitter separation, and directional emitter alignment. This unique cathode structure was unachievable by other methods. The developed FE devices successfully solved the screening effect issue encounter by current FE devices. The laser-control oxidation method was further developed to sequentially remove graphitic walls of CNTs. The laser oxidation process was directed to occur along the CNT axes by the laser scanning direction. Additionally, the oxidation was further assisted by the curvature stress and the thermal expansion of the graphitic nanotubes, ultimately opening (namely unzipping) the tubular structure to produce GNRs. Therefore the developed laser scanning method optimally exploited the thermal laser-CNT interaction, successfully transforming CNTs into 2D GNRs. The solid-state laser unzipping process effectively addressed the issues of contamination and scalability encountered by the current unzipping methods. Additionally, the produced GNRs were uniquely featured with the freestanding structure and the smooth surfaces. If the scanning process was performed in an inert environment without the appearance of oxygen, the oxidation of CNTs would not happen. Instead, the greatly mobile carbon atoms of the heated CNTs would reorganize the crystal structure, inducing the graphitization process to improve the crystallinity. Many observations showing the structural improvement of CNTs under laser irradiation has been reported, confirming the capability of laser to heal graphitic defects. Laser methods were more time-efficient and energy-efficient than other annealing methods because laser can quickly heat CNTs to generate graphitization in less than one second. This subsecond heating process of laser irradiation was more effective than other heating methods because it avoided the undesired coalescence of CNTs. In my research, the laser scanning method was applied to generate the graphitization, healing the structural defects of CNTs. Different from the reported laser methods, the laser scanning directed the locally annealed areas to move along the CNT axes, migrating and coalescencing the graphitic defects to achieve better healing results. The critical information describing the CNT structural transformation caused by the moving laser irradiation was explored from the successful applications of the developed laser method. This knowledge inspires an important method to modifiy the general graphitic structure for important applications, such as carbon fiber production, CNT self-assembly process and CNT welding. This method will be effective, facile, versatile, and adaptable for laboratory and industrial facilities.

ORGANIZATION 6, NOVA SCIENCE UNIT 7.

ERIC Educational Resources Information Center

1964

DIRECTIONS FOR CONDUCTING A SERIES OF SCIENCE EXPERIMENTS ARE PRESENTED. THE EXPERIMENTS CONCERN THE STUDY OF HEAT AND MOLECULAR MOTION, HEAT EXCHANGE IN A MIXTURE, SPECIFIC HEAT, HEAT AND SIZE, EXPANSION OF LIQUID, EXPANSION OF AIR, HEAT OF FUSION OF ICE, HEAT OF VAPORIZATION OF WATER, LIGHT AND SOUND, LAW OF REFLECTION, PLANE MIRROR IMAGES,…

Temperature and heat flux datasets of a complex object in a fire plume for the validation of fire and thermal response codes.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jernigan, Dann A.; Blanchat, Thomas K.

It is necessary to improve understanding and develop temporally- and spatially-resolved integral scale validation data of the heat flux incident to a complex object in addition to measuring the thermal response of said object located within the fire plume for the validation of the SIERRA/FUEGO/SYRINX fire and SIERRA/CALORE codes. To meet this objective, a complex calorimeter with sufficient instrumentation to allow validation of the coupling between FUEGO/SYRINX/CALORE has been designed, fabricated, and tested in the Fire Laboratory for Accreditation of Models and Experiments (FLAME) facility. Validation experiments are specifically designed for direct comparison with the computational predictions. Making meaningful comparisonmore » between the computational and experimental results requires careful characterization and control of the experimental features or parameters used as inputs into the computational model. Validation experiments must be designed to capture the essential physical phenomena, including all relevant initial and boundary conditions. This report presents the data validation steps and processes, the results of the penlight radiant heat experiments (for the purpose of validating the CALORE heat transfer modeling of the complex calorimeter), and the results of the fire tests in FLAME.« less

Impact of measurable physical phenomena on contact thermal comfort

NASA Astrophysics Data System (ADS)

Fojtlín, Miloš; Pokorný, Jan; Fišer, Jan; Toma, Róbert; Tuhovčák, Ján

Cabin HVAC (Heating Ventilation and Air-conditioning) systems have become an essential part of personal vehicles as demands for comfortable transport are still rising. In fact, 85 % of the car trips in Europe are shorter than 18 km and last only up to 30 minutes. Under such conditions, the HVAC unit cannot often ensure desired cabin environment and passengers are prone to experience thermal stress. For this reason, additional comfort systems, such as heated or ventilated seats, are available on the market. However, there is no straightforward method to evaluate thermal comfort at the contact surfaces nowadays. The aim of this work is to summarise information about heated and ventilated seats. These technologies use electrical heating and fan driven air to contact area in order to achieve enhanced comfort. It is also expected, that such measures may contribute to lower energy consumption. Yet, in real conditions it is almost impossible to measure the airflow through the ventilated seat directly. Therefore, there is a need for an approach that would correlate measurable physical phenomena with thermal comfort. For this reason, a method that exploits a measurement of temperatures and humidity at the contact area is proposed. Preliminary results that correlate comfort with measurable physical phenomena are demonstrated.

Efficiently reducing transition curvature in heat-assisted magnetic recording with state-of-the-art write heads

NASA Astrophysics Data System (ADS)

Vogler, Christoph; Abert, Claas; Bruckner, Florian; Suess, Dieter

2017-05-01

Curvatures of bit transitions on granular media are a serious problem for the read-back process. We address this fundamental issue and propose a possibility to efficiently reduce transition curvatures with state-of-the-art heat-assisted magnetic recording heads. We compare footprints of conventional with those of the proposed head design on different media, consisting of exchange coupled and single phase grains. Additionally, we investigate the impact of various recording parameters, such as the full width at half maximum (FWHM) of the applied heat pulse and the coercivity gradient near the write temperature of the recording grains. The footprints are calculated with a coarse grained model, based on the Landau-Lifshitz-Bloch equation. The presented simulations show a transition curvature reduction of up to 40%, in the case of a medium with exchange coupled grains and a heat pulse with a FWHM of 40 nm. We further give the reason for the straightening of the bit transitions, by means of basic considerations with regard to the effective recording time window of the write process. Besides the transition curvature reduction, the proposed head design yields an improvement of the transition jitter in both down-track and off-track directions.

Graded pitch electromagnetic pump for thin strip metal casting systems

DOEpatents

Kuznetsov, S.B.

1986-04-01

A metal strip casing system is provided with an electromagnetic pump which includes a pair of primary blocks having a graded pole pitch, polyphase ac winding and being arranged on opposite sides of a movable heat sink. A nozzle is provided for depositing liquid metal on the heat sink such that the resulting metal strip and heat sink combination is subjected to a longitudinal electromagnetic field which increases in wavelength in the direction of travel of the heat sink, thereby subjecting the metal and heat sink to a longitudinal force having a magnitude which increases in the direction of travel. 4 figs.

The effect of cover use on plastic pyrolysis reactor heating process

NASA Astrophysics Data System (ADS)

Armadi, Benny H.; Rangkuti, Chalilullah; Fauzi, M. D.; Permatasari, R.

2017-03-01

Plastic pyrolysis process to produce liquid fuel is an endothermic process that uses heat from the combustion of fuel as heat source. The reactor used is usually a vertical cylindrical in shape, with LPG fuel combustion under the flat bottom of the reactor, and the combustion gases is dispersed into the surrounding environment, so that heat transferred to the plastic inside the reactor is not effective, causing high LPG consumption. In this study, the reactor is made of stainless steel plate, with a vertical cylindrical shape, with a basic cylindrical conical truncated by a pit pass hot flue gas in the middle that serves to deliver flue gas into the chimney. The contact area between the hot combusted LPG gases to the processed plastic inside the reactor becomes bigger and gets better heat transfer, and required less LPG consumption. For more effective heat transfer process, an outer cover of this reactor was made and the relatively hot combustion gases are used to heat the outside of the reactor by directing the flow of the flue gas from the chimney down along the outer wall of the reactor and out the bottom lid. This construction makes the heating process to be faster and the LPG fuel is used more efficiently. From the measurements, it was found to raise 1°C of temperature inside the covered reactor, the LPG consumed is 0.59 gram, and if the reactor cover is removed, the gas demand will rise nearly threefold to 1.43 grams. With this method, in addition to reducing the rate of heat loss will also help reduce LPG consumption significantly.

Class I and II Small Heat Shock Proteins Together with HSP101 Protect Protein Translation Factors during Heat Stress.

PubMed

McLoughlin, Fionn; Basha, Eman; Fowler, Mary E; Kim, Minsoo; Bordowitz, Juliana; Katiyar-Agarwal, Surekha; Vierling, Elizabeth

2016-10-01

The ubiquitous small heat shock proteins (sHSPs) are well documented to act in vitro as molecular chaperones to prevent the irreversible aggregation of heat-sensitive proteins. However, the in vivo activities of sHSPs remain unclear. To investigate the two most abundant classes of plant cytosolic sHSPs (class I [CI] and class II [CII]), RNA interference (RNAi) and overexpression lines were created in Arabidopsis (Arabidopsis thaliana) and shown to have reduced and enhanced tolerance, respectively, to extreme heat stress. Affinity purification of CI and CII sHSPs from heat-stressed seedlings recovered eukaryotic translation elongation factor (eEF) 1B (α-, β-, and γ-subunits) and eukaryotic translation initiation factor 4A (three isoforms), although the association with CI sHSPs was stronger and additional proteins involved in translation were recovered with CI sHSPs. eEF1B subunits became partially insoluble during heat stress and, in the CI and CII RNAi lines, showed reduced recovery to the soluble cell fraction after heat stress, which was also dependent on HSP101. Furthermore, after heat stress, CI sHSPs showed increased retention in the insoluble fraction in the CII RNAi line and vice versa. Immunolocalization revealed that both CI and CII sHSPs were present in cytosolic foci, some of which colocalized with HSP101 and with eEF1Bγ and eEF1Bβ. Thus, CI and CII sHSPs have both unique and overlapping functions and act either directly or indirectly to protect specific translation factors in cytosolic stress granules. © 2016 American Society of Plant Biologists. All Rights Reserved.

Influence of environmental temperature on prolificacy of pigs.

PubMed

Wettemann, R P; Bazer, F W

1985-01-01

Exposure of male and female pigs to elevated ambient temperatures can result in reduced reproductive efficiency. When boars and gilts are exposed to heat stress, respiratory rates increase to enhance evaporative cooling because minimal sweating occurs. During early pregnancy, gilts are especially susceptible to heat stress. Decreased conception rates and reduced litter size occur when gilts are exposed to elevated ambient temperature during Days 0 to 16 after mating. Concentrations of progesterone in peripheral plasma were reduced during Days 13-19 after mating and luteal function was extended to Day 25 in heat-stressed gilts that did not conceive. Increased concentrations of oestradiol during Day 10 to 12 of heat stress may interfere with normal maternal recognition of pregnancy. Heat stress reduced the amount of embryonic tissue present at Day 16 of pregnancy but the protein synthetic activity of the tissue was not altered. Thus some embryos may be lost and a reduction in litter size may occur. The production of oestrogen by the conceptus and uterus is not altered on Day 16, after exposure to heat stress for the previous 8 days. These studies suggest that heat stress during early pregnancy can alter the reproductive endocrine system, especially the control of luteal function. In addition, heat stress may have a direct effect on embryo or conceptus development. Exposure of boars to elevated ambient temperatures causes reductions in semen quality, sperm output and fertility. About 5 weeks are required for boars to recover from the detrimental effects of heat stress and to produce semen with potential for maximal fertility. Increased temperature has an inhibitory effect on spermatid maturation and on testicular androgen biosynthesis. Improvements in reproductive performance can be achieved by increasing evaporative cooling of boars.

Development of Rapid Pipe Moulding Process for Carbon Fiber Reinforced Thermoplastics by Direct Resistance Heating

NASA Astrophysics Data System (ADS)

Tanaka, Kazuto; Harada, Ryuki; Uemura, Toshiki; Katayama, Tsutao; Kuwahara, Hideyuki

To deal with environmental issues, the gasoline mileage of passenger cars can be improved by reduction of the car weight. The use of car components made of Carbon Fiber Reinforced Plastics (CFRP) is increasing because of its superior mechanical properties and relatively low density. Many vehicle structural parts are pipe-shaped, such as suspension arms, torsion beams, door guard bars and impact beams. A reduction of the car weight is expected by using CFRP for these parts. Especially, when considering the recyclability and ease of production, Carbon Fiber Reinforced Thermoplastics are a prime candidate. On the other hand, the moulding process of CFRTP pipes for mass production has not been well established yet. For this pipe moulding process an induction heating method has been investigated already, however, this method requires a complicated coil system. To reduce the production cost, another system without such complicated equipment is to be developed. In this study, the pipe moulding process of CFRTP using direct resistance heating was developed. This heating method heats up the mould by Joule heating using skin effect of high-frequency current. The direct resistance heating method is desirable from a cost perspective, because this method can heat the mould directly without using any coils. Formerly developed Non-woven Stitched Multi-axial Cloth (NSMC) was used as semi-product material. NSMC is very suitable for the lamination process due to the fact that non-crimp stitched carbon fiber of [0°/+45°/90°/-45°] and polyamide 6 non-woven fabric are stitched to one sheet, resulting in a short production cycle time. The use of the pipe moulding process with the direct resistance heating method in combination with the NSMC, has resulted in the successful moulding of a CFRTP pipe of 300 mm in length, 40 mm in diameter and 2 mm in thickness.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bryant, M.; Starkey, A.H.; Dick-Peddie, W.A.

A brief overview of the present day geothermal applications for hydrothermal electrical generation and direct heat use and their environmental implications is provided. Technologies and environmental impacts are considered at all points on the pathway of development resource exploration; well field, plant and transmission line construction; and plant operation. The technologies for electrical generation-direct, dry steam conversion; separated steam conversion; single-flash conversion, separated-steam/single-flash conversion and binary cycle conversion and the technologies for direct heat use - direct use of geothermal waters, surface heat exhanger, down-the hole heat exchanger and heat pump are described. A summary of the geothermal technologies plannedmore » or in operation within New Mexico geothermal areas is provided. A review of regulations that affect geothermal development and its related environmental impact in New Mexico is presented. The regulatory pathway, both state and federal, of geothermal exploration after the securing of appropriate leases, development, and construction and implementation of a geothermal facility are described. Six categories (Geophysical, Water, Air, Noise, Biota and Socioeconomics) were selected for environmental assessment. The data available is described.« less

Heat Pipes

NASA Technical Reports Server (NTRS)

1991-01-01

Phoenix Refrigeration Systems, Inc.'s heat pipe addition to the Phoenix 2000, a supermarket rooftop refrigeration/air conditioning system, resulted from the company's participation in a field test of heat pipes. Originally developed by NASA to control temperatures in space electronic systems, the heat pipe is a simple, effective, heat transfer system. It has been used successfully in candy storage facilities where it has provided significant energy savings. Additional data is expected to fully quantify the impact of the heat pipes on supermarket air conditioning systems.

New Nomenclatures for Heat Treatments of Additively Manufactured Titanium Alloys

NASA Astrophysics Data System (ADS)

Baker, Andrew H.; Collins, Peter C.; Williams, James C.

2017-07-01

The heat-treatment designations and microstructure nomenclatures for many structural metallic alloys were established for traditional metals processing, such as casting, hot rolling or forging. These terms do not necessarily apply for additively manufactured (i.e., three-dimensionally printed or "3D printed") metallic structures. The heat-treatment terminology for titanium alloys generally implies the heat-treatment temperatures and their sequence relative to a thermomechanical processing step (e.g., forging, rolling). These designations include: β-processing, α + β-processing, β-annealing, duplex annealing and mill annealing. Owing to the absence of a thermomechanical processing step, these traditional designations can pose a problem when titanium alloys are first produced via additive manufacturing, and then heat-treated. This communication proposes new nomenclatures for heat treatments of additively manufactured titanium alloys, and uses the distinct microstructural features to provide a correlation between traditional nomenclature and the proposed nomenclature.

40 CFR 60.4176 - Additional requirements to provide heat input data.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Additional requirements to provide heat... Compliance Times for Coal-Fired Electric Steam Generating Units Monitoring and Reporting § 60.4176 Additional requirements to provide heat input data. The owner or operator of a Hg Budget unit that monitors and reports Hg...

Direct exposure to mild heat promotes proliferation and neuronal differentiation of neural stem/progenitor cells in vitro

PubMed Central

Hossain, Md Emon; Katakura, Masanori; Sugimoto, Naotoshi; Mamun, Abdullah Al; Islam, Rafiad; Hashimoto, Michio; Shido, Osamu

2017-01-01

Heat acclimation in rats is associated with enhanced neurogenesis in thermoregulatory centers of the hypothalamus. To elucidate the mechanisms for heat acclimation, we investigated the effects of direct mild heat exposure on the proliferation and differentiation of neural stem/progenitor cells (NSCs/NPCs). The NSCs/NPCs isolated from forebrain cortices of 14.5-day-old rat fetuses were propagated as neurospheres at either 37.0°C (control) or 38.5°C (mild heat exposure) for four days, and the effects on proliferation were investigated by MTS cell viability assay, measurement of neurosphere diameter, and counting the total number of cells. The mRNA expressions of heat shock proteins (HSPs) and brain-derived neurotrophic factor (BDNF), cAMP response element-binding (CREB) protein and Akt phosphorylation levels, and intracellular reactive oxygen species (ROS) levels were analyzed using real time PCR, Western blotting and CM-H2DCFDA assay respectively. Heat exposure under proliferation condition increased NSC/NPC viability, neurosphere diameter, and cell count. BDNF mRNA expression, CREB phosphorylation, and ROS level were also increased by heat exposure. Heat exposure increased HSP27 mRNA expression concomitant with enhanced p-Akt level. Moreover, treatment with LY294002 (a PI3K inhibitor) abolished the effects of heat exposure on NSC/NPC proliferation. Furthermore, heat exposure under differentiation conditions increased the proportion of cells positive for Tuj1 (a neuronal marker). These findings suggest that mild heat exposure increases NSC/NPC proliferation, possibly through activation of the Akt pathway, and also enhances neuronal differentiation. Direct effects of temperature on NSCs/NPCs may be one of the mechanisms involved in hypothalamic neurogenesis in heat-acclimated rats. Such heat-induced neurogenesis could also be an effective therapeutic strategy for neurodegenerative diseases. PMID:29287093

Direct-Interface, Fusible Heat Sink

NASA Technical Reports Server (NTRS)

Lomax, Curtis; Webbon, Bruce

1992-01-01

Nonventing, regenerable, and self-contained heat sink absorbs heat in melting of ice by direct contact with forced flow of warm water. Elastic bladder contains water and ice. Connectors designed to prevent leaks easily connectable and disconnectable. Female portions embedded in wall of heat sink. After water frozen, male portions inserted and flow of warm water initiated. Water melts ice in and around female connectors, then flow passes between ice and bladder from inlet to outlet. Component of low-power portable refrigerator to operate for short time in picnic or camp setting.

Corrosion Behavior of Additive Manufactured Ti-6Al-4V Alloy in NaCl Solution

NASA Astrophysics Data System (ADS)

Yang, Jingjing; Yang, Huihui; Yu, Hanchen; Wang, Zemin; Zeng, Xiaoyan

2017-07-01

The microstructures, potentiodynamic curves, and electrochemical impedance spectroscopy are characterized for Ti-6Al-4V samples produced by selective laser melting (SLM), SLM followed by heat treatment (HT), wire and arc additive manufacturing (WAAM), and traditional rolling to investigate their corrosion behaviors. Results show that the processing technology acts a significant role in controlling the microstructures, which in turn directly determine their corrosion resistance. The order of corrosion resistance of these samples is SLM < WAAM < rolling < SLM+HT. Among these microstructural factors for influencing corrosion resistance, type of constituent phase is the main one, followed by grain size, and the last is morphology. Finally, the application potentials of additive manufactured Ti-6Al-4V alloy are verified in the aspect of corrosion resistance.

Evaluating Cool Impervious Surfaces: Application to an Energy-Efficient Residential Roof and to City Pavements

NASA Astrophysics Data System (ADS)

Rosado, Pablo Javier

Summer urban heat island (UHI) refers to the phenomenon of having higher urban temperatures compared to the those in surrounding suburban and rural areas. Higher urban air temperatures lead to increased cooling demand, accelerates the formation of smog, and contributes to the generation of greenhouse gas emissions. Dark-colored impervious surfaces cover a significant fraction of an urban fabric, and as hot and dry surfaces, are a major contributor to the UHI effect. Adopting solar-reflective ("cool") roofs and cool pavements, and increasing the urban vegetation, are strategies proven to mitigate urban heat islands. These strategies often have an "indirect" effect (ambient cooling) and "direct" effect (change in solar energy flux entering the conditioned space) on the energy use of buildings. This work investigates some elements of the UHI mitigation strategies, specifically the annual direct effect of a cool roof, and the direct and indirect effects of cool pavements. The first topic researched in this paper consists in an experimental assessment of the direct effects from replacing a conventional dark roof with a highly energy-efficient cool roof. The study measures and calculates the annual benefits of the cool roof on the cooling and heating energy uses, and the associated emission reductions. The energy savings attributed to the cool roof are validated by measuring the difference between the homes in the heat loads that entered the conditioned space through the ceiling and HVAC ducts. Fractional annual cooling energy savings (26%) were 2.6 times the 10% daily cooling energy savings measured in a previous study that used a white coating to increase the albedo of an asphalt shingle roof by the same amount (0.44). The improved cooling energy savings (26% vs. 10%) may be attributed to the cool tile's above-sheathing ventilation, rather than to its high thermal mass. The roof also provided energy savings during the heating season, yielding fractional annual gas heating savings of 4% and electric heating savings of 3%. The slightly positive fractional annual heating energy savings likely resulted from the tile roof's high thermal capacitance, which increased the overnight temperature of the attic air. Thus cool tile roofs should be perceived as a technology that provides energy and environmental benefits during the cooling season as well as the heating season. The second topic investigates the direct and indirect effects of cool pavements on the energy use of California's building stock. First, a simple urban canyon model was developed to calculate the canyon albedo after the user provides the solar position, canyon orientation, and dimensions of the canyon walls, road, and setbacks. Next, a method is presented to correct the values of temperature changes obtained from previous urban climate models to values that would be obtained from canyon geometries that distinguish between road and setbacks (e.g. sidewalk, front yard). The new canyon model is used to scale the temperature changes obtained from a recent urban climate model that simulated the climatological impact of cool pavements on various California cities. The adjusted temperature changes are then combined with building energy simulations to investigate the effect of cool pavements on the cooling, heating, and lighting energy uses of buildings as well as the environmental impact related to these energy uses. Net (direct + indirect) conditioning (cooling + heating) energy savings and environmental savings from cool pavements were smaller in residential buildings than in commercial buildings. Additionally, residential buildings strongly dominate the building stock in all of the evaluated cities. Therefore, even though most cities yielded conditioning energy and environmental savings, they were small due to the minuscule savings from the residential buildings. When increasing the albedo by 0.20 of all public pavements in different California cities, Los Angeles was the city with the largest savings, yielding only 0.60% in Primary Energy Demand and 0.30% in Global Warming Potential (GWP). Some of the cities experienced even a small net penalty in GWP of up to 0.20%.

Long pulse acceleration of MeV class high power density negative H{sup −} ion beam for ITER

DOE Office of Scientific and Technical Information (OSTI.GOV)

Umeda, N., E-mail: umeda.naotaka@jaea.go.jp; Kojima, A.; Kashiwagi, M.

2015-04-08

R and D of high power density negative ion beam acceleration has been carried out at MeV test facility in JAEA to realize ITER neutral beam accelerator. The main target is H{sup −} ion beam acceleration up to 1 MeV with 200 A/m{sup 2} for 60 s whose pulse length is the present facility limit. For long pulse acceleration at high power density, new extraction grid (EXG) has been developed with high cooling capability, which electron suppression magnet is placed under cooling channel similar to ITER. In addition, aperture size of electron suppression grid (ESG) is enlarged from 14 mmmore » to 16 mm to reduce direct interception on the ESG and emission of secondary electron which leads to high heat load on the upstream acceleration grid. By enlarging ESG aperture, beam current increased 10 % at high current beam and total acceleration grid heat load reduced from 13 % to 10 % of input power at long pulse beam. In addition, heat load by back stream positive ion into the EXG is measured for the first time and is estimated as 0.3 % of beam power, while heat load by back stream ion into the source chamber is estimated as 3.5 ~ 4.0 % of beam power. Beam acceleration up to 60 s which is the facility limit, has achieved at 683 keV, 100 A/m{sup 2} of negative ion beam, whose energy density increases two orders of magnitude since 2011.« less

Data indicating temperature response of Ti-6Al-4V thin-walled structure during its additive manufacture via Laser Engineered Net Shaping.

PubMed

Marshall, Garrett J; Thompson, Scott M; Shamsaei, Nima

2016-06-01

An OPTOMEC Laser Engineered Net Shaping (LENS(™)) 750 system was retrofitted with a melt pool pyrometer and in-chamber infrared (IR) camera for nondestructive thermal inspection of the blown-powder, direct laser deposition (DLD) process. Data indicative of temperature and heat transfer within the melt pool and heat affected zone atop a thin-walled structure of Ti-6Al-4V during its additive manufacture are provided. Melt pool temperature data were collected via the dual-wavelength pyrometer while the dynamic, bulk part temperature distribution was collected using the IR camera. Such data are provided in Comma Separated Values (CSV) file format, containing a 752×480 matrix and a 320×240 matrix of temperatures corresponding to individual pixels of the pyrometer and IR camera, respectively. The IR camera and pyrometer temperature data are provided in blackbody-calibrated, raw forms. Provided thermal data can aid in generating and refining process-property-performance relationships between laser manufacturing and its fabricated materials.

Data indicating temperature response of Ti–6Al–4V thin-walled structure during its additive manufacture via Laser Engineered Net Shaping

PubMed Central

Marshall, Garrett J.; Thompson, Scott M.; Shamsaei, Nima

2016-01-01

An OPTOMEC Laser Engineered Net Shaping (LENS™) 750 system was retrofitted with a melt pool pyrometer and in-chamber infrared (IR) camera for nondestructive thermal inspection of the blown-powder, direct laser deposition (DLD) process. Data indicative of temperature and heat transfer within the melt pool and heat affected zone atop a thin-walled structure of Ti–6Al–4V during its additive manufacture are provided. Melt pool temperature data were collected via the dual-wavelength pyrometer while the dynamic, bulk part temperature distribution was collected using the IR camera. Such data are provided in Comma Separated Values (CSV) file format, containing a 752×480 matrix and a 320×240 matrix of temperatures corresponding to individual pixels of the pyrometer and IR camera, respectively. The IR camera and pyrometer temperature data are provided in blackbody-calibrated, raw forms. Provided thermal data can aid in generating and refining process-property-performance relationships between laser manufacturing and its fabricated materials. PMID:27054180

Redesigned Human Metabolic Simulator

NASA Technical Reports Server (NTRS)

Duffield, Bruce; Jeng, Frank; Lange, Kevin

2008-01-01

A design has been formulated for a proposed improved version of an apparatus that simulates atmospheric effects of human respiration by introducing controlled amounts of carbon dioxide, water vapor, and heat into the air. Denoted a human metabolic simulator (HMS), the apparatus is used for testing life-support equipment when human test subjects are not available. The prior version of the HMS, to be replaced, was designed to simulate the respiratory effects of as many as four persons. It exploits the catalytic combustion of methyl acetate, for which the respiratory quotient (the molar ratio of carbon dioxide produced to oxygen consumed) is very close to the human respiratory quotient of about 0.86. The design of the improved HMS provides for simulation of the respiratory effects of as many as eight persons at various levels of activity. The design would also increase safety by eliminating the use of combustion. The improved HMS (see figure) would include a computer that would exert overall control. The computer would calculate the required amounts of oxygen removal, carbon dioxide addition, water addition, and heat addition by use of empirical equations for metabolic profiles of respiration and heat. A blower would circulate air between the HMS and a chamber containing a life-support system to be tested. With the help of feedback from a mass flowmeter, the blower speed would be adjusted to regulate the rate of flow according to the number of persons to be simulated and to a temperature-regulation requirement (the air temperature would indirectly depend on the rate of flow, among other parameters). Oxygen would be removed from the circulating air by means of a commercially available molecular sieve configured as an oxygen concentrator. Oxygen, argon, and trace amounts of nitrogen would pass through a bed in the molecular sieve while carbon dioxide, the majority of nitrogen, and other trace gases would be trapped by the bed and subsequently returned to the chamber. If, as recommended, the oxygen concentrator were of a rotating twelve-bed design, then variations in the product stream could be made very small. Carbon dioxide would be added directly to the circulating air by simple injection from a supply tank. The rate of injection would be maintained at the required rate by use of a mass flowmeter/controller. In the same way, nitrogen would be added to make up for the small amount of nitrogen lost through the oxygen concentrator. Water vapor would be added to the circulating air by heating the corresponding required flow of water to steam in a heat exchanger. More heat, required to complete the simulation of the thermal effect of respiration, would be added through another heat exchanger. Heat would be supplied to both heat exchangers via a hot-oil loop.

SUBCOOLING DETECTOR

DOEpatents

McCann, J.A.

1963-12-17

A system for detecting and measuring directly the subcooling margin in a liquid bulk coolant is described. A thermocouple sensor is electrically heated, and a small amount of nearly stagnant bulk coolant is heated to the boiling point by this heated thermocouple. The sequential measurement of the original ambient temperature, zeroing out this ambient temperature, and then measuring the boiling temperature of the coolant permits direct determination of the subcooling margin of the ambient liquid. (AEC)

Prototype solar heating and combined heating and cooling systems

NASA Technical Reports Server (NTRS)

1977-01-01

System analysis activities were directed toward refining the heating system parameters. Trade studies were performed to support hardware selections for all systems and for the heating only operational test sites in particular. The heating system qualification tests were supported by predicting qualification test component performance prior to conducting the test.

Thermal protection apparatus

DOEpatents

Bennett, G.A.; Elder, M.G.; Kemme, J.E.

1984-03-20

The disclosure is directed to an apparatus for thermally protecting sensitive components in tools used in a geothermal borehole. The apparatus comprises a Dewar within a housing. The Dewar contains heat pipes such as brass heat pipes for thermally conducting heat from heat sensitive components such as electronics to a heat sink such as ice.

Simulation and economic analysis of a liquid-based solar system with a direct-contact liquid-liquid heat exchanger, in comparison to a system with a conventional heat exchanger

NASA Astrophysics Data System (ADS)

Brothers, P.; Karaki, S.

Using a solar computer simulation package called TRNSYS, simulations of the direct contact liquid-liquid heat exchanger (DCLLHE) solar system and a system with conventional shell-and-tube heat exchanger were developed, based in part on performance measurements of the actual systems. The two systems were simulated over a full year on an hour-by-hour basis at five locations; Boston, Massachusetts, Charleston, South Carolina, Dodge City, Kansas, Madison, Wisconsin, and Phoenix, Arizona. Typically the direct-contact system supplies slightly more heat for domestic hot water and space heating in all locations and about 5 percentage points more cooling as compared to the conventional system. Using a common set of economic parameters and the appropriate federal and state income tax credits, as well as property tax legislation for solar systems in the corresponding states, the results of the study indicate for heating-only systems, the DCLLHE system has a slight life-cycle cost disadvantage compared to the conventional system. For combined solar heating and cooling systems, the DCLLHE has a slight life-cycle cost advantage which varies with location and amounts to one to three percent difference from the conventional system.

Cold Heat Release Characteristics of Solidified Oil Droplet-Water Solution Latent Heat Emulsion by Air Bubbles

NASA Astrophysics Data System (ADS)

Inaba, Hideo; Morita, Shin-Ichi

The present work investigates the cold heat-release characteristics of the solidified oil droplets (tetradecane, C14H30, freezing point 278.9 K)/water solution emulsion as a latent heat-storage material having a low melting point. An air bubbles-emulsion direct-contact heat exchange method is selected for the cold heat-results from the solidified oil droplet-emulsion layer. This type of direct-contact method results in the high thermal efficiency. The diameter of air bubbles in the emulsion increases as compared with that in the pure water. The air bubbles blown from a nozzle show a strong mixing behavior during rising in the emulsion. The temperature effectiveness, the sensible heat release time and the latent heat release time have been measured as experimental parameters. The useful nondimensional emulsion level equations for these parameters have been derived in terms of the nondimensional emalsion level expressed the emulsion layer dimensions, Reynolds number for air flow, Stefan number and heat capacity ratio.

CFD modelling wall heat transfer inside a combustion chamber using ANSYS forte

NASA Astrophysics Data System (ADS)

Plengsa-ard, C.; Kaewbumrung, M.

2018-01-01

A computational model has been performed to analyze a wall heat transfer in a single cylinder, direct injection and four-stroke diesel engine. A direct integration using detailed chemistry CHEMKIN is employed in a combustion model and the Reynolds Averaged Navier Stokes (RANS) turbulence model is used to simulate the flow in the cylinder. To obtain heat flux results, a modified classical variable-density wall heat transfer model is also performed. The model is validated using experimental data from a CUMMINs engine operated with a conventional diesel combustion. One operating engine condition is simulated. Comparisons of simulated in-cylinder pressure and heat release rates with experimental data shows that the model predicts the cylinder pressure and heat release rates reasonably well. The contour plot of instantaneous temperature are presented. Also, the contours of predicted heat flux results are shown. The magnitude of peak heat fluxes as predicted by the wall heat transfer model is in the range of the typical measure values in diesel combustion.

Analysis of solar water heater with parabolic dish concentrator and conical absorber

NASA Astrophysics Data System (ADS)

Rajamohan, G.; Kumar, P.; Anwar, M.; Mohanraj, T.

2017-06-01

This research focuses on developing novel technique for a solar water heating system. The novel solar system comprises a parabolic dish concentrator, conical absorber and water heater. In this system, the conical absorber tube directly absorbs solar radiation from the sun and the parabolic dish concentrator reflects the solar radiations towards the conical absorber tube from all directions, therefore both radiations would significantly improve the thermal collector efficiency. The working fluid water is stored at the bottom of the absorber tubes. The absorber tubes get heated and increases the temperature of the working fluid inside of the absorber tube and causes the working fluid to partially evaporate. The partially vaporized working fluid moves in the upward direction due to buoyancy effect and enters the heat exchanger. When fresh water passes through the heat exchanger, temperature of the vapour decreases through heat exchange. This leads to condensation of the vapour and forms liquid phase. The working fluid returns to the bottom of the collector absorber tube by gravity. Hence, this will continue as a cyclic process inside the system. The proposed investigation shows an improvement of collector efficiency, enhanced heat transfer and a quality water heating system.

Effect of heat treatment on the characteristics of tool steel deposited by the directed energy deposition process

NASA Astrophysics Data System (ADS)

Park, Jun Seok; Lee, Min-Gyu; Cho, Yong-Jae; Sung, Ji Hyun; Jeong, Myeong-Sik; Lee, Sang-Kon; Choi, Yong-Jin; Kim, Da Hye

2016-01-01

The directed energy deposition process has been mainly applied to re-work and the restoration of damaged steel. Differences in material properties between the base and the newly deposited materials are unavoidable, which may affect the mechanical properties and durability of the part. We investigated the effect of heat treatment on the characteristics of tool steel deposited by the DED process. We prepared general tool steel materials of H13 and D2 that were deposited onto heat-treated substrates of H13 and D2, respectively, using a direct metal tooling process. The hardness and microstructure of the deposited steel before and after heat treatment were investigated. The hardness of the deposited H13 steel was higher than that of wrought H13 steel substrate, while that of the deposited D2 was lower than that of wrought D2. The evolution of the microstructures by deposition and heat treatment varied depending on the materials. In particular, the microstructure of the deposited D2 steel after heat treatment consisted of fine carbides in tempered martensite and it is expected that the deposited D2 steel will have isotropic properties and high hardness after heat treatment.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barleon, L.; Buehler, L.; Molokov, S.

Magnetohydrodynamic (MHD) flow through a 90{degrees} bend, in which the flow is turned from the direction perpendicular to magnetic field lines into a direction aligned with the field, is characterized by strong three-dimensional effects leading to additional pressure drop and large deformations in the velocity distribution. Since such bends are basic elements of a fusion reactor blanket, the question whether the additional pressure drop exceeds unacceptable limits or whether the change in flow distribution may lead to unfavorable heat transfer conditions as to be answered. To investigate MHD flows in a right angle bend, several experiments have been performed inmore » a wide range of the relevant parameters. In the lower range of the interaction parameter N (N {much_lt} 10{sup 4}) the total pressure drop over the whole bend shows a pronounced N-dependence but only a weak dependence on the Hartmann number M. Both effects can be combined to a pressure drop correlation. At higher values of N and M the experimental results for pressure drop and potential distribution agree rather well with theoretical ones obtained on the basis of an asymptotic approach for high N and M. It can be shown theoretically and confirmed by the experiment that, even at high N and M the additional pressure drop in a right angle bend is not excessively high. For the investigated bend with conducting channel walls the predicted flow distribution does not show any stagnant zone at the high heat flux walls in the perfectly aligned part of the duct. This result, however, could not be checked experimentally because there is still no reliable velocity measurement technique available for field-aligned flows.« less

Heat-directed tumor cell fusion.

PubMed

Brade, Anthony M; Szmitko, Paul; Ngo, Duc; Liu, Fei-Fei; Klamut, Henry J

2003-03-20

In previous studies we demonstrated that a modified human HSP70b promoter (HSE.70b) directs high levels of gene expression to tumor cells after mild hyperthermia treatment in the range of 41.5-44 degrees C. This transcriptional targeting system exhibits low basal activity at 37 degrees C, is highly induced (950-fold) after mild heat treatment (43 degrees C/30 min), and returns to basal activity levels within 12-24 hours of activation. Here we describe heat-directed targeting of an activated form of the Gibbon ape leukemia virus env protein (GALV FMG) to tumor cells. GALV FMG mediates cell-cell fusion, and when expressed in tumor cells can produce bystander effects of up to 1:200. Transient transfection of a HSE70b.GALV FMG minigene caused extensive syncytia formation in HeLa and HT-1080 cells following mild heat treatment (44 degrees C/30 min). Stable transfection into HT-1080 cells produced a cell line (HG5) that exhibits massive syncytia formation and a 60% reduction in viability relative to a vector-only control (CI1) following heat treatment in vitro. Mild hyperthermia also resulted in syncytia formation, necrosis, and complete macroscopic regression of HG5 xenograft tumors grown in the footpads of mice with severe combined immunodeficiency disorders (SCID). Median survival increased from 12.5 (in heated CI1 controls) to 52 days after a single heat treatment. Heat-directed tumor cell fusion may prove to be a highly beneficial adjunct to existing cancer treatment strategies that take advantage of the synergistic interaction between mild hyperthermia and radiation or chemotherapeutic drugs.

The Response of the Ocean Thermal Skin Layer to Air-Sea Surface Heat Fluxes

NASA Astrophysics Data System (ADS)

Wong, Elizabeth Wing-See

There is much evidence that the ocean is heating as a result of an increase in concentrations of greenhouse gases (GHGs) in the atmosphere from human activities. GHGs absorb infrared radiation and re-emit infrared radiation back to the ocean's surface which is subsequently absorbed. However, the incoming infrared radiation is absorbed within the top micrometers of the ocean's surface which is where the thermal skin layer exists. Thus the incident infrared radiation does not directly heat the upper few meters of the ocean. We are therefore motivated to investigate the physical mechanism between the absorption of infrared radiation and its effect on heat transfer at the air-sea boundary. The hypothesis is that since heat lost through the air-sea interface is controlled by the thermal skin layer, which is directly influenced by the absorption and emission of infrared radiation, the heat flow through the thermal skin layer adjusts to maintain the surface heat loss, assuming the surface heat loss does not vary, and thus modulates the upper ocean heat content. This hypothesis is investigated through utilizing clouds to represent an increase in incoming longwave radiation and analyzing retrieved thermal skin layer vertical temperature profiles from a shipboard infrared spectrometer from two research cruises. The data are limited to night-time, no precipitation and low winds of less than 2 m/s to remove effects of solar radiation, wind-driven shear and possibilities of thermal skin layer disruption. The results show independence of the turbulent fluxes and emitted radiation on the incident radiative fluxes which rules out the immediate release of heat from the absorption of the cloud infrared irradiance back into the atmosphere through processes such as evaporation and increase infrared emission. Furthermore, independence was confirmed between the incoming and outgoing radiative flux which implies the heat sink for upward flowing heat at the air-sea interface is more-or-less fixed. The surplus energy, from absorbing increasing levels of infrared radiation, is found to adjust the curvature of the thermal skin layer such that there is a smaller gradient at the interface between the thermal skin layer and the mixed layer beneath. The vertical conduction of heat from the mixed layer to the surface is therefore hindered while the additional energy within the thermal skin layer is supporting the gradient changes of the skin layer's temperature profile. This results in heat beneath the thermal skin layer, which is a product of the absorption of solar radiation during the day, to be retained and cause an increase in upper ocean heat content. The accuracy of four published skin layer models were evaluated by comparison with the field results. The results show a need to include radiative effects, which are currently absent, in such models as they do not replicate the findings from the field data and do not elucidate the effects of the absorption of infrared radiation.

Significantly High Thermal Rectification in an Asymmetric Polymer Molecule Driven by Diffusive versus Ballistic Transport.

PubMed

Ma, Hao; Tian, Zhiting

2018-01-10

Tapered bottlebrush polymers have novel nanoscale polymer architecture. Using nonequilibrium molecular dynamics simulations, we showed that these polymers have the unique ability to generate thermal rectification in a single polymer molecule and offer an exceptional platform for unveiling different heat conduction regimes. In sharp contrast to all other reported asymmetric nanostructures, we observed that the heat current from the wide end to the narrow end (the forward direction) in tapered bottlebrush polymers is smaller than that in the opposite direction (the backward direction). We found that a more disordered to less disordered structural transition within tapered bottlebrush polymers is essential for generating nonlinearity in heat conduction for thermal rectification. Moreover, the thermal rectification ratio increased with device length, reaching as high as ∼70% with a device length of 28.5 nm. This large thermal rectification with strong length dependence uncovered an unprecedented phenomenon-diffusive thermal transport in the forward direction and ballistic thermal transport in the backward direction. This is the first observation of radically different transport mechanisms when heat flow direction changes in the same system. The fundamentally new knowledge gained from this study can guide exciting research into nanoscale organic thermal diodes.

Energy Efficient Clothes Dryer with IR Heating and Electrostatic Precipitator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weaver, Stanton

The project goal was to develop a revolutionary energy saving technology for residential clothes drying. The team developed an IR (infrared) heating system and NESP (Nebulizer and Electro-Static Precipitator) for integration into a ventless clothes dryer. The proposed technology addresses two of the major inefficiencies in current electric vented dryers by providing effective energy transfer for the removal of the water and recapture of the vapor latent heat. The IR heaters operating in the mid wave (2.5-10um) are very efficient as they target the 3-micron peak absorption of the water molecule. This allows direct energy absorption, unlike conventional element heatersmore » where heat is transferred by convection. The low power NESP removes water vapor from the exhausted stream and recaptures the latent heat in the ESP (Electro-Static Precipitator) exchanger section. This allows the warm dry air to be recirculated back into the drum for additional efficiency savings. The remaining majority of the dryer hardware stays the same. Summing the efficiency gain from the two subcomponents we anticipated the EF (Efficiency Factor) to exceed the goal of 4.04. EF is obtained by dividing the weight (lbs) of water removed by the energy (kWhr) used, where the test load size is 8.45 lbs of bone dry clothing wetted to 57.5% or 4.8lbs of water, and dried to a remaining moisture content of 2.5-5%. Additional benefits include not having to recondition (heat or cool) the large amounts of make-up air to replace the air exhausted by a vented dryer. It was anticipated that the NESP/heat exchanger would be the most challenging and highest risk element in the program. Therefore, the team focused their efforts during Phase 1 of the program on the design, construction, testing, and optimization of the NESP/heat exchanger. At the end Phase 1, the team compared the performance of the NESP/heat exchanger with the system level requirements and made a Go/No-Go decision on proceeding with the second portion of the program. Phase 2 of the program was structured to develop the IR heating system and then integrate it and the NESP/heat exchanger into a residential clothes dryer prototype for final testing. The proposed technology utilizes heat recovery which is known to have the biggest impact on dryer efficiency. The two current mainstream recovery approaches are air to air exchangers and heat pump condenser systems. Air to air exchanges can be very efficient but require large surface areas which are prone to fouling from uncaptured lint. Dryers based on heat pump condenser recovery systems have shown efficiency improvements of 20–60% and are commercially available. The issue with a heat pump condenser approach is the added cost, as typical prices are twice that of standard vented dryers and they are only available in small to medium capacities. The energy factor (EF) for these systems is 5.50 to 6.88 pounds/kWh compared to conventional dryers at 2.75 to 3.67 pounds/kWh. The efficiency improvements for the proposed technology come from the use of IR heating and the NESP. As the concept is in its infancy, and these improvements were difficult to predict without experimental data, assumptions were made based on available literature. IR radiant drying times, when compared to convection, are typically 30% less. This is a result of the fact that radiant energy heats directly and is absorbed at and below the surface, unlike convection heating, that must conduct the heat through the boundary film of air at the clothes surface and rely on wicking of the moisture to the surface. The second area of improvement comes from the NESP. The NESP operation is as follows: 1. Highly charged, micron sized, droplets of water are injected into the dryer exhaust by the Nebulizer. 2. These charged droplets attract water molecules and continue to grow in size, until losing their charge. During this process, latent heat is rejected back into the air stream. 3. The large droplets enter the ESP, where they are recharged and drawn to the ESP wall, to be extracted at the bottom of the ESP. The warm dry air is then recirculated back into the dryer. The proposed technology, at the time of the proposal submission was estimated to have an EF of 4.79. At program completion we have designed, built, tested, integrated and optimized the proposed technologies into a prototype “high efficiency” residential clothes dryer. Testing of the integrated prototype dryer provided insight into the technical effectiveness and economic feasibility of the proposed technologies. The program has the potential of greatly impacting energy savings. The predicted EF of the proposed technology is 4.79, yielding an energy savings of 42% when compared to conventional electric vented dryers. Given there are approximately 84 million dryers in the US consuming ~64 billion kWh per year, a net savings of 27 billion kWh per year or 0.092 quads could be realized. Since the dryer is not vented, make up air from the room is not needed, adding an additional savings of ~1kWh per load, or 23.8 billion kWh per year. In addition, it is envisioned that the proposed ESP, when successful, would potentially find applications in industrial and residential dehumidification.« less

Effects of spatial gradients in thermophysical properties on the topology of turbulence in heated channel flow of supercritical fluids

NASA Astrophysics Data System (ADS)

Azih, Chukwudi; Yaras, Metin I.

2018-01-01

The current literature suggests that large spatial gradients of thermophysical properties, which occur in the vicinity of the pseudo-critical thermodynamic state, may result in significant variations in forced-convection heat transfer rates. Specifically, these property gradients induce inertia- and buoyancy-driven phenomena that may enhance or deteriorate the turbulence-dominated heat convection process. Through direct numerical simulations, the present study investigates the role of coherent flow structures in channel geometries for non-buoyant and buoyant flows of supercritical water, with buoyant configurations involving wall-normal oriented gravitational acceleration and downstream-oriented gravitational acceleration. This sequence of simulations enables the evaluation of the relative contributions of inertial and buoyancy phenomena to heat transfer variations. In these simulations, the state of the working fluid is in the vicinity of the pseudo-critical point. The uniform wall heat flux and the channel mass flux are specified such that the heat to mass flux ratio is 3 kJ/kg, with an inflow Reynolds number of 12 000 based on the channel hydraulic diameter, the area-averaged inflow velocity, and fluid properties evaluated at the bulk temperature and pressure of the inflow plane. In the absence of buoyancy forces, notable reductions in the density and viscosity in close proximity of the heated wall are observed to promote generation of small-scale vortices, with resultant breakdown into smaller scales as they interact with preexisting larger near-wall vortices. This interaction results in a reduction in the overall thermal mixing at particular wall-normal regions of the channel. Under the influence of wall-normal gravitational acceleration, the wall-normal density gradients are noted to enhance ejection motions due to baroclinic vorticity generation on the lower wall, thus providing additional wall-normal thermal mixing. Along the upper wall, the same mechanism generates streamwise vorticity of the opposing sense of rotation in the close vicinity to the respective legs of the hairpin vortices causing a net reduction in thermal mixing. Finally, in the case of downstream-oriented gravitational acceleration, baroclinic vorticity generation as per spanwise density gradients causes additional wall-normal thermal mixing by promoting larger-scale ejection and sweep motions.

The controllable electron-heating by external magnetic fields at relativistic laser-solid interactions in the presence of large scale pre-plasmas

NASA Astrophysics Data System (ADS)

Wu, D.; Luan, S. X.; Wang, J. W.; Yu, W.; Gong, J. X.; Cao, L. H.; Zheng, C. Y.; He, X. T.

2017-06-01

The two-stage electron acceleration/heating model (Wu et al 2017 Nucl. Fusion 57 016007 and Wu et al 2016 Phys. Plasmas 23 123116) is extended to the study of laser magnetized-plasmas interactions at relativistic intensities and in the presence of large-scale preformed plasmas. It is shown that the electron-heating efficiency is a controllable value by the external magnetic fields. Detailed studies indicate that for a right-hand circularly polarized laser, the electron heating efficiency depends on both strength and directions of external magnetic fields. The electron-heating is dramatically enhanced when the external magnetic field is of B\\equiv {ω }c/{ω }0> 1. When magnetic field is of negative direction, i.e. B< 0, it trends to suppress the electron heating. The underlining physics—the dependences of electron-heating on both the strength and directions of the external magnetic fields—is uncovered. With -∞ < B< 1, the electron-heating is explained by the synergetic effects by longitudinal charge separation electric field and the reflected ‘envelop-modulated’ CP laser. It is indicated that the ‘modulation depth’ of reflected CP laser is significantly determined by the external magnetic fields, which will in turn influence the efficiency of the electron-heating. While with B> 1, a laser front sharpening mechanism is identified at relativistic laser magnetized-plasmas interactions, which is responsible for the dramatical enhancement of electron-heating.

Additional double-wall roof in single-wall, closed, convective incubators: Impact on body heat loss from premature infants and optimal adjustment of the incubator air temperature.

PubMed

Delanaud, Stéphane; Decima, Pauline; Pelletier, Amandine; Libert, Jean-Pierre; Stephan-Blanchard, Erwan; Bach, Véronique; Tourneux, Pierre

2016-09-01

Radiant heat loss is high in low-birth-weight (LBW) neonates. Double-wall or single-wall incubators with an additional double-wall roof panel that can be removed during phototherapy are used to reduce Radiant heat loss. There are no data on how the incubators should be used when this second roof panel is removed. The aim of the study was to assess the heat exchanges in LBW neonates in a single-wall incubator with and without an additional roof panel. To determine the optimal thermoneutral incubator air temperature. Influence of the additional double-wall roof was assessed by using a thermal mannequin simulating a LBW neonate. Then, we calculated the optimal incubator air temperature from a cohort of human LBW neonate in the absence of the additional roof panel. Twenty-three LBW neonates (birth weight: 750-1800g; gestational age: 28-32 weeks) were included. With the additional roof panel, R was lower but convective and evaporative skin heat losses were greater. This difference can be overcome by increasing the incubator air temperature by 0.15-0.20°C. The benefit of an additional roof panel was cancelled out by greater body heat losses through other routes. Understanding the heat transfers between the neonate and the environment is essential for optimizing incubators. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

Comparison of advanced thermal and electrical storage for parabolic dish solar thermal power systems

NASA Astrophysics Data System (ADS)

Fujita, T.; Birur, G. C.; Schredder, J. M.; Bowyer, J. M.; Awaya, H. I.

Parabolic dish solar concentrator cluster concepts are explored, with attention given to thermal storage systems coupled to Stirling and Brayton cycle power conversion devices. Sensible heat storage involving molten salt (NaOH), liquid sodium, and solid cordierite bricks are considered for 1500 F thermal storage systems. Latent heat storage with NaF-MgF2 phase change materials are explored in terms of passive, active, and direct contact designs. Comparisons are made of the effectiveness of thermal storage relative to redox, Na-S, Zn-Cl, and Zn-Br battery storage systems. Molten lead trickling down through a phase change eutectic, the NaF-MgF2, formed the direct contact system. Heat transport in all systems is effected through Inconel pipes. Using a cost goal of 120-150 mills/kWh as the controlling parameter, sensible heat systems with molten salts transport with either Stirling or Brayton engines, or latent heat systems with Stirling engines, and latent heat-Brayton engine with direct contact were favored in the analyses. Battery storage systems, however, offered the most flexibility of applications.

Comparison of advanced thermal and electrical storage for parabolic dish solar thermal power systems

NASA Technical Reports Server (NTRS)

Fujita, T.; Birur, G. C.; Schredder, J. M.; Bowyer, J. M.; Awaya, H. I.

1982-01-01

Parabolic dish solar concentrator cluster concepts are explored, with attention given to thermal storage systems coupled to Stirling and Brayton cycle power conversion devices. Sensible heat storage involving molten salt (NaOH), liquid sodium, and solid cordierite bricks are considered for 1500 F thermal storage systems. Latent heat storage with NaF-MgF2 phase change materials are explored in terms of passive, active, and direct contact designs. Comparisons are made of the effectiveness of thermal storage relative to redox, Na-S, Zn-Cl, and Zn-Br battery storage systems. Molten lead trickling down through a phase change eutectic, the NaF-MgF2, formed the direct contact system. Heat transport in all systems is effected through Inconel pipes. Using a cost goal of 120-150 mills/kWh as the controlling parameter, sensible heat systems with molten salts transport with either Stirling or Brayton engines, or latent heat systems with Stirling engines, and latent heat-Brayton engine with direct contact were favored in the analyses. Battery storage systems, however, offered the most flexibility of applications.

Better latent heat and specific heat of stearic acid with magnetite/graphene nanocomposite addition for thermal storage application

NASA Astrophysics Data System (ADS)

Andiarto, R.; Nuryadin, M. K.; Taufik, A.; Saleh, R.

2017-04-01

In our previous study, the addition of Magnetite (Fe3O4) into Stearic acid (Sa) as an organic phase change material (PCM) shows an enhancement in the latent heat for thermal energy storage applications. The latent heat of the PCM can also be increased by adding graphene material. Therefore, in this research, the thermal properties of Sa have been studied by the sonication method for several different concentrations of Fe3O4/Graphene nanocomposite additions. The structural properties of all of the samples were observed by X-Ray diffraction (XRD). Melting-solidifying behavior and specific heat value were measured by differential scanning calorimetry (DSC). The thermal degradation process of all samples was investigated by thermogravimetric analysis (TGA). Based on the DSC results, the presence of Fe3O4/Graphene in the Sa enhances the latent heat up to 20%. The specific heat value of the mixture was also found to be increased as the concentration of Fe3O4/Graphene to Sa increased. The TGA results show a lowered thermal degradation process of the Sa by the addition of the Fe3O4/Graphene which indicates a higher thermal stability of the mixture. In conclusion, the results demonstrate that the addition of Fe3O4/Graphene to Sa improves both the sensible heat and the latent heat of the mixture which are very important for thermal energy storage applications

40 CFR 60.4176 - Additional requirements to provide heat input data.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 6 2011-07-01 2011-07-01 false Additional requirements to provide heat... requirements to provide heat input data. The owner or operator of a Hg Budget unit that monitors and reports Hg... monitor and report heat input rate at the unit level using the procedures set forth in part 75 of this...

Development of a Direct Contact Heat Exchanger, Phase 1 Study Report

NASA Technical Reports Server (NTRS)

Manvi, R.

1978-01-01

Electric power generation from geothermal brine requires, first, bringing the hot brine to the surface and then converting the heat to electric power. Binary conversion schemes were proposed, with the heat transfer between the brine and the working organic fluid taking place in a conventional tube and shell heat exchanger. If the brine is heavily laden with dissolved solids, however, solids buildup on the heat exchanger surfaces leads to a considerable degree of fouling and an accompanying drop in performance is experienced. A possible solution to this problem is the use of a direct contact exchanger with the secondary fluid power cycle. The proposed concept involves the formation of fluid sheets and bells as heat angles. Results of a study concerning the fluid mechanics of such surfaces are given.

Loading mode dependent effective properties of octet-truss lattice structures using 3D-printing

NASA Astrophysics Data System (ADS)

Challapalli, Adithya

Cellular materials, often called lattice materials, are increasingly receiving attention for their ultralight structures with high specific strength, excellent impact absorption, acoustic insulation, heat dissipation media and compact heat exchangers. In alignment with emerging additive manufacturing (AM) technology, realization of the structural applications of the lattice materials appears to be becoming faster. Considering the direction dependent material properties of the products with AM, by directionally dependent printing resolution, effective moduli of lattice structures appear to be directionally dependent. In this paper, a constitutive model of a lattice structure, which is an octet-truss with a base material having an orthotropic material property considering AM is developed. In a case study, polyjet based 3D printing material having an orthotropic property with a 9% difference in the principal direction provides difference in the axial and shear moduli in the octet-truss by 2.3 and 4.6%. Experimental validation for the effective properties of a 3D printed octet-truss is done for uniaxial tension and compression test. The theoretical value based on the micro-buckling of truss member are used to estimate the failure strength. Modulus value appears a little overestimate compared with the experiment. Finite element (FE) simulations for uniaxial compression and tension of octettruss lattice materials are conducted. New effective properties for the octet-truss lattice structure are developed considering the observed behavior of the octet-truss structure under macroscopic compression and tension trough simulations.

Understanding the Benefits and Limitations of Magnetic Nanoparticle Heating for Improved Applications in Cancer Hyperthermia and Biomaterial Cryopreservation

NASA Astrophysics Data System (ADS)

Etheridge, Michael L.

The current work focused on the ability of magnetic nanoparticles to produce heat in the presence of an applied alternating magnetic field. Magnetic nanoparticle hyperthermia applications utilize this behavior to treat cancer and this approach has received clinical approval in the European Union, but significant developments are necessary for this technology to have a chance for wider-spread acceptance. Here then we begin by investigating some of the important limitations of the current technology. By characterizing the ability of superparamagnetic and ferromagnetic nanoparticles to heat under a range of applied fields, we are able to determine the optimal field settings for clinical application and make recommendations on the highest impact strategies to increase heating. In addition, we apply these experimentally determined limits to heating in a series of heat transfer models, to demonstrate the therapeutic impact of nanoparticle concentration, target volume, and delivery strategy. Next, we attempt to address one of the key questions facing the field- what is the impact of biological aggregation on heating? Controlled aggregate populations are produced and characterized in ionic and protein solutions and their heating is compared with nanoparticles incubated in cellular suspensions. Through this investigation we are able to demonstrate that aggregation is responsible for up to a 50% decrease in heating. However, more importantly, we are able to demonstrate that the observed reductions in heating correlate with reductions in longitudinal relaxation (T1) measured by sweep imaging with Fourier transformation (SWIFT) magnetic resonance imaging (MRI), providing a potential platform to account for these aggregation effects and directly predict heating in a clinical setting. Finally, we present a new application for magnetic nanoparticle heating, in the thawing of cryopreserved biomaterials. A number of groups have demonstrated the ability to rapidly cool and preserve tissues in the vitreous state, but crystallization and cracking failures occur upon the subsequent thaw. Magnetic nanoparticles offer a potential solution to these issues, through their ability to provide rapid, uniform heating, and we illustrate this through heating in several cryoprotectant solutions and by modeling the effects of heating at the bulk and micro-scales.

Nonequilibrium life-cycles in Ocean Heat Content

NASA Astrophysics Data System (ADS)

Weiss, Jeffrey B.; Fox-Kemper, Baylor; Mandal, Dibyendu; Zia, Royce K. P.

2014-03-01

Natural climate variability can be considered as fluctuations in a nonequilibrium steady state. A fundamental property of nonequilibrium steady states is the phase space current which provides a preferred direction for fluctuations, and is manifested as preferred life-cycles for climate fluctuations. We propose a new quantity, the phase space angular momentum, to quantify the phase space rotation. In analogy with traditional angular momentum, which quantifies the rotation of mass in physical space, the phase space angular momentum quantifies the rotation of probability in phase space. It has the additional advantage that it is straightforward to calculate from a time series. We investigate the phase space angular momentum for fluctuations in ocean heat content in both observations and ocean general circulation models. We gratefully acknowledge financial support from the National Science Foundation (USA) under grant OCE 1245944.

Nonimaging optics maximizing exergy for hybrid solar system

NASA Astrophysics Data System (ADS)

Winston, Roland; Jiang, Lun; Abdelhamid, Mahmoud; Widyolar, Bennett K.; Ferry, Jonathan; Cygan, David; Abbasi, Hamid; Kozlov, Alexandr; Kirk, Alexander; Elarde, Victor; Osowski, Mark

2016-09-01

The project team of University of California at Merced (UC-Merced), Gas Technology Institute (GTI) and MicroLink Devices Inc. (MicroLink) are developing a hybrid solar system using a nonimaging compound parabolic concentrator (CPC) that maximizes the exergy by delivering direct electricity and on-demand heat. The hybrid solar system technology uses secondary optics in a solar receiver to achieve high efficiency at high temperature, collects heat in particles and uses reflective liftoff cooled double junction (2J) InGaP/GaAs solar cells with backside infrared (IR) reflectors on the secondary optical element to raise exergy efficiency. The nonimaging optics provides additional concentration towards the high temperature thermal stream and enables it to operate efficiently at 650 °C while the solar cell is maintained at 40 °C to operate as efficiently as possible.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rice, S.; Algora, A.; Tain, J. L.

The beta decays of Br-86 and Rb-91 have been studied using the total absorption spectroscopy technique. The radioactive nuclei were produced at the Ion Guide Isotope Separator On-Line facility in Jyvaskyla and further purified using the JYFLTRAP. Br-86 and Rb-91 are considered to be major contributors to the decay heat in reactors. In addition, Rb-91 was used as a normalization point in direct measurements of mean gamma energies released in the beta decay of fission products by Rudstam et al. assuming that this decaywas well known from high-resolution measurements. Our results show that both decays were suffering from the Pandemoniummore » effect and that the results of Rudstam et al. should be renormalized. The relative impact of the studied decays in the prediction of the decay heat and antineutrino spectrum from reactors has been evaluated.« less

Pressure waves in liquid mercury target from pulsed heat loads and the possible way controlling their effects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ni, L.; Skala, K.

1996-06-01

In ESS project liquid metals are selected as the main target for the pulsed spallation neutron source. Since the very high instantaneous energy is deposited on the heavy molten target in a very short period time, pressure waves are generated. They travel through the liquid and cause high stress in the container. Also, additional stress should be considered in the wall which is the result of direct heating of the target window. These dynamic processes were simulated with computational codes with the static response being analized first. The total resulting dynamic wall stress has been found to have exceeded themore » design stress for the selected container material. Adding a small amount of gas bubbles in the liquid could be a possible way to reduce the pressure waves.« less

Impact Toughness of Subzones in the Intercritical Heat-Affected Zone of Low-Carbon Bainitic Steel.

PubMed

Li, Zhenshun; Zhao, Xuemin; Shan, Dongri

2018-06-06

The subzones of the intercritical heat-affected zone (IC HAZ) of low-carbon bainitic steel were simulated by using a Gleeble-3500 simulator to study the impact toughness. The results showed that the IC HAZ is not entirely brittle and can be further divided into three subzones according to the impact toughness or peak welding temperature; the invariant subzone heated between the critical transformation start temperature ( A c1 ) and 770 °C exhibited unchanged high impact toughness. Furthermore, an extremely low impact toughness was found in the embrittlement subzone, heated between 770 and 830 °C, and the reduction subzone heated between 830 °C and the critical transformation finish temperature ( A c3 ) exhibited toughness below that of the original metal. The size of the blocky martensite-austenite (M-A) constituents was found to have a remarkable level of influence on the impact toughness when heated below 830 °C. Additionally, it was found that, once the constituent size exceeds a critical value of 3.0 µm at a peak temperature of 770 °C, the IC HAZ becomes brittle regardless of lath or twinned martensite constitution in the M-A constituent. Essentially, embrittlement was observed to occur when the resolved length of initial cracks (in the direction of the overall fracture) formed as a result of the debonding of M-A constituents exceeding the critical Griffith size. Furthermore, when the heating temperature exceeded 830 °C, the M-A constituents formed a slender shape, and the impact toughness increased as the area fraction of the slender M-A constituents decreased.

An extended supersonic combustion model for the dynamic analysis of hypersonic vehicles

NASA Technical Reports Server (NTRS)

Bossard, J. A.; Peck, R. E.; Schmidt, D. K.

1993-01-01

The development of an advanced dynamic model for aeroelastic hypersonic vehicles powered by air breathing engines requires an adequate engine model. This report provides a discussion of some of the more important features of supersonic combustion and their relevance to the analysis and design of supersonic ramjet engines. Of particular interest are those aspects of combustion that impact the control of the process. Furthermore, the report summarizes efforts to enhance the aeropropulsive/aeroelastic dynamic model developed at the Aerospace Research Center of Arizona State University by focusing on combustion and improved modeling of this flow. The expanded supersonic combustor model described here has the capability to model the effects of friction, area change, and mass addition, in addition to the heat addition process. A comparison is made of the results from four cases: (1) heat addition only; (2) heat addition plus friction; (3) heat addition, friction, and area reduction, and (4) heat addition, friction, area reduction, and mass addition. The relative impact of these effects on the Mach number, static temperature, and static pressure distributions within the combustor are then shown. Finally, the effects of frozen versus equilibrium flow conditions within the exhaust plume is discussed.

Counter-extrapolation method for conjugate interfaces in computational heat and mass transfer.

PubMed

Le, Guigao; Oulaid, Othmane; Zhang, Junfeng

2015-03-01

In this paper a conjugate interface method is developed by performing extrapolations along the normal direction. Compared to other existing conjugate models, our method has several technical advantages, including the simple and straightforward algorithm, accurate representation of the interface geometry, applicability to any interface-lattice relative orientation, and availability of the normal gradient. The model is validated by simulating the steady and unsteady convection-diffusion system with a flat interface and the steady diffusion system with a circular interface, and good agreement is observed when comparing the lattice Boltzmann results with respective analytical solutions. A more general system with unsteady convection-diffusion process and a curved interface, i.e., the cooling process of a hot cylinder in a cold flow, is also simulated as an example to illustrate the practical usefulness of our model, and the effects of the cylinder heat capacity and thermal diffusivity on the cooling process are examined. Results show that the cylinder with a larger heat capacity can release more heat energy into the fluid and the cylinder temperature cools down slower, while the enhanced heat conduction inside the cylinder can facilitate the cooling process of the system. Although these findings appear obvious from physical principles, the confirming results demonstrates the application potential of our method in more complex systems. In addition, the basic idea and algorithm of the counter-extrapolation procedure presented here can be readily extended to other lattice Boltzmann models and even other computational technologies for heat and mass transfer systems.

Novel desiccant cooling system using indirect evaporative cooler

DOE Office of Scientific and Technical Information (OSTI.GOV)

Belding, W.A.; Delmas, M.P.F.

1997-12-31

An effective desiccant cooling system must efficiently reject adsorption and carryover heat from the process airstream. Rotary heat exchangers are typically used to remove this heat in currently available desiccant equipment, but these devices can leak humid air from the regeneration side of the process into the dry process side, degrading performance. Using a different approach, high cooling capacities and coefficients of performance (COPs) have been achieved in a desiccant cooling system without a heat wheel or bulky stationary heat exchanger. Using a desiccant wheel in conjunction with a compact indirect evaporative cooler and a small air-to-air heat exchanger, amore » cooling system has been developed that eliminates the need for deep dehumidification by the desiccant wheel and at the same time provides 25% to 35% ventilation air to the conditioned space. Using a 0.68 m (27 in.) diameter by 0.2 m (8 in.) deep type 1 M desiccant wheel regenerated at 175 C (347 F), 15.0 kW (4.3 tons) of cooling were achieved with a thermal COP of 0.72. With the addition of a direct evaporative cooler, humidity control over a broad range can be offered by the system. The low desiccant wheel volume and the compact nature of the indirect evaporative coolers result in equipment with a low potential first cost, assuming economies of scale. Equipment presently under development is expected to exceed a gross cooling COP of 0.9.« less

Agar-Silica-Gel Heating Phantom May Be Suitable for Long-Term Quality Assurance of MRgHIFU

NASA Astrophysics Data System (ADS)

Partanen, Ari

2009-04-01

In MRgHIFU, the purpose of frequent quality assurance is to detect changes in system performance to prevent adverse effects during treatments. Due to high ultrasound intensities in MRgHIFU, it is essential to assure that the procedure is safe and efficacious and that image-based guidance of the treatment is reliable. We aimed to develop a guideline for MRgHIFU QA by acquiring MR temperature maps during ultrasonic heating of an agar-silica-gel phantom over a four month-period using three separate MRgHIFU uterine leiomyoma treatment systems. From this data, the stability of the maximum temperature elevation, the targeting accuracy, and the dimensions of the heated volume were analyzed. Additionally, we studied the sensitivity of these parameters to reveal hypothetical decrease in HIFU performance. After calibration, the mean targeting offsets of the heated volume were observed to be less than 2 mm in the three orthogonal directions. The measured maximum temperature elevation and the length and the width of the heated volume remained consistent throughout the four-month period. Furthermore, it was found that the parameters under investigation were sensitive to reveal the decreased HIFU performance. We conclude that an agar-silica -based phantom is suitable for targeting accuracy and heating properties QA of MRgHIFU system even in long-term use. Moreover, this simple QA method may be used to reveal small changes in HIFU performance assuring consistent functionality and safety of the MRgHIFU system.

Comparison of Turbulent Heat-Transfer Results for Uniform Wall Heat Flux and Uniform Wall Temperature

NASA Technical Reports Server (NTRS)

Siegel, R.; Sparrow, E. M.

1960-01-01

The purpose of this note is to examine in a more precise way how the Nusselt numbers for turbulent heat transfer in both the fully developed and thermal entrance regions of a circular tube are affected by two different wall boundary conditions. The comparisons are made for: (a) Uniform wall temperature (UWT); and (b) uniform wall heat flux (UHF). Several papers which have been concerned with the turbulent thermal entrance region problem are given. 1 Although these analyses have all utilized an eigenvalue formulation for the thermal entrance region there were differences in the choices of eddy diffusivity expressions, velocity distributions, and methods for carrying out the numerical solutions. These differences were also found in the fully developed analyses. Hence when making a comparison of the analytical results for uniform wall temperature and uniform wall heat flux, it was not known if differences in the Nusselt numbers could be wholly attributed to the difference in wall boundary conditions, since all the analytical results were not obtained in a consistent way. To have results which could be directly compared, computations were carried out for the uniform wall temperature case, using the same eddy diffusivity, velocity distribution, and digital computer program employed for uniform wall heat flux. In addition, the previous work was extended to a lower Reynolds number range so that comparisons could be made over a wide range of both Reynolds and Prandtl numbers.

Histologic investigation of the human pulp after thermodebonding of metal and ceramic brackets.

PubMed

Jost-Brinkmann, P G; Stein, H; Miethke, R R; Nakata, M

1992-11-01

Twenty-five human permanent teeth scheduled for extraction for orthodontic reasons were used to study the effect of thermodebonding on the pulp tissue. One week before brackets were removed the teeth were bonded with either metal or ceramic brackets, with two alternative adhesives. For debonding, three different techniques were used: (1) debonding of ceramic brackets warmed up indirectly by resistance heating of a metallic bow applied to the bracket slot, (2) debonding of metal brackets warmed up directly by inductive heating of the bracket itself, and (3) debonding of ceramic brackets warmed up indirectly by inductive heating of metallic plier tips, applied to the mesial and distal bracket surfaces. Teeth with metal brackets removed without heat by squeezing the wings together served as a control group. The teeth were extracted 24 hours after debonding and subjected to a light microscopic study after histologic preparation and staining. In addition, the location of adhesive remnants was evaluated. While the thermodebonding of metal brackets worked properly and without any obvious pulp damage, there were problems related to the thermodebonding of ceramic brackets: (1) if more than one heating cycle was necessary, several teeth showed localized damage of the pulp with slight infiltration of inflammatory cells, (2) bracket fractures occurred frequently, and enamel damage could be shown, and (3) often with Transbond (Unitek/3M, Monrovia, Calif.) as the adhesive, more than one heating cycle was necessary for bracket removal, and thus patients complained about pain.

Work-related heat stress concerns in automotive industries: a case study from Chennai, India

PubMed Central

Ayyappan, Ramalingam; Sankar, Sambandam; Rajkumar, Paramasivan; Balakrishnan, Kalpana

2009-01-01

Background Work-related heat stress assessments, the quantification of thermal loads and their physiological consequences have mostly been performed in non-tropical developed country settings. In many developing countries (many of which are also tropical), limited attempts have been made to create detailed job-exposure profiles for various sectors. We present here a case study from Chennai in southern India that illustrates the prevalence of work-related heat stress in multiple processes of automotive industries and the efficacy of relatively simple controls in reducing prevalence of the risk through longitudinal assessments. Methods We conducted workplace heat stress assessments in automotive and automotive parts manufacturing units according to the protocols recommended by NIOSH, USA. Sites for measurements included indoor locations with process-generated heat exposure, indoor locations without direct process-generated heat exposure and outdoor locations. Nearly 400 measurements of heat stress were made over a four-year period at more than 100 locations within eight units involved with automotive or automotive parts manufacturing in greater Chennai metropolitan area. In addition, cross-sectional measurements were made in select processes of glass manufacturing and textiles to estimate relative prevalence of heat stress. Results Results indicate that many processes even in organised large-scale industries have yet to control heat stress-related hazards adequately. Upwards of 28% of workers employed in multiple processes were at risk of heat stress-related health impairment in the sectors assessed. Implications of longitudinal baseline data for assessing efficacy of interventions as well as modelling potential future impacts from climate change (through contributions from worker health and productivity impairments consequent to increases in ambient temperature) are described. Conclusions The study re-emphasises the need for recognising heat stress as an important occupational health risk in both formal and informal sectors in India. Making available good baseline data is critical for estimating future impacts. PMID:20052426

Effect of HF Heating Array Directivity Pattern on the Frequency Response of Generated ELF/VLF.

DTIC Science & Technology

1983-01-01

radiators ....... ............ 4 1-2 HF heating array ........ ................... 9 1-3 HF heating array element ...... ................ 9 1-4 View of top...elements looking down at pyramid ....... 9 1-5 Non-planar log-periodic antenna semi-structure dimensions ............ . ....... 10 l-6a Power gain vs...22 1-8 Orientation of 4- and 8-element arrays .. ......... .. 24 1- 9 Comparison of experimental and theoretical patterns. . . 27 1-10 Directive

Rotigotine Transdermal Patch

MedlinePlus

... other sources of heat such as heating pads, electric blankets and heated waterbeds; or direct sunlight. Do ... you suddenly fall asleep. Do not drive a car or operate machinery at the beginning of your ...

Evaluation of Canisterized Foams and Evaluation of Radiation Hardened Foams for D&D Activities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nicholson, J. C.

The introduction of polyurethane foams has previously been examined elsewhere within the DOE complex with regards to decontamination and decommissioning (D&D) activities, though its use has been prohibited as a result of excessive heat generation and flammability concerns per the safety basis. Should these foams be found compatible with respect to the facility safety basis requirements, D&D work involving large void containing structures such as gloveboxes could be eased through the fixation of residual contamination after decontamination efforts have concluded. To this end, SRNL embarked on a characterization of commercial epoxy foams to identify the characteristics that would be mostmore » important to safety basis requirements. Through SRNL’s efforts, the performance of commercial two-part epoxy foams was evaluated for their foaming characteristics, temperature profiles, loading capability with high-Z (high density) additives, and applicability for shielding gamma emission from isotopes including; Am-241, Cs-137, and Co-60. It was found that these foams are capable of encapsulation of a desired volume, though the ideal and experimental expansion coefficients were found to differ. While heat is generated during the reaction, no samples generated heat above 70 °C. Of the down–selected materials, heating was on the order of 40 °C for the flexible foam and 60 °C for the rigid foam. Both were found to return to room temperature after 20 minutes regardless of the volume of foam cast. It was also found that the direct introduction of high-Z additives were capable of attenuating 98% of Am-241 gamma signal, 16% of Cs-137 signal, and 9.5% of Co-60 signal at 1:1 loading capacities of total liquid constituent weight to additive weight. These efforts are currently being reviewed for the ASTM January 2017 subcommittee discussions to address the lack of test methods and standards regarding these materials with respect to D&D environments.« less

Experimental analysis of direct-expansion ground-coupled heat pump systems

NASA Astrophysics Data System (ADS)

Mei, V. C.; Baxter, V. D.

1991-09-01

Direct-expansion ground-coil-coupled (DXGC) heat pump systems have certain energy efficiency advantages over conventional ground-coupled heat pump (GCHP) systems. Principal among these advantages are that the secondary heat transfer fluid heat exchanger and circulating pump are eliminated. While the DXGC concept can produce higher efficiencies, it also produces more system design and environmental problems (e.g., compressor starting, oil return, possible ground pollution, and more refrigerant charging). Furthermore, general design guidelines for DXGC systems are not well documented. A two-pronged approach was adopted for this study: (1) a literature survey, and (2) a laboratory study of a DXGC heat pump system with R-22 as the refrigerant, for both heating and cooling mode tests done in parallel and series tube connections. The results of each task are described in this paper. A set of general design guidelines was derived from the test results and is also presented.

Heat transfer degradation during condensation of non-azeotropic mixtures

NASA Astrophysics Data System (ADS)

Azzolin, M.; Berto, A.; Bortolin, S.; Del, D., Col

2017-11-01

International organizations call for a reduction of the HFCs production and utilizations in the next years. Binary or ternary blends of hydroflourocarbons (HFCs) and hydrofluoroolefins (HFOs) are emerging as possible substitutes for high Global Warming Potential (GWP) fluids currently employed in some refrigeration and air-conditioning applications. In some cases, these mixtures are non-azeotropic and thus, during phase-change at constant pressure, they present a temperature glide that, for some blends, can be higher than 10 K. Such temperature variation during phase change could lead to a better matching between the refrigerant and the water temperature profiles in a condenser, thus reducing the exergy losses associated with the heat transfer process. Nevertheless, the additional mass transfer resistance which occurs during the phase change of zeotropic mixtures leads to a heat transfer degradation. Therefore, the design of a condenser working with a zeotropic mixture poses the problem of how to extend the correlations developed for pure fluids to the case of condensation of mixtures. Experimental data taken are very helpful in the assessment of design procedures. In the present paper, heat transfer coefficients have been measured during condensation of zeotropic mixtures of HFC and HFO fluids. Tests have been carried out in the test rig available at the Two Phase Heat Transfer Lab of University of Padova. During the condensation tests, the heat is subtracted from the mixture by using cold water and the heat transfer coefficient is obtained from the measurement of the heat flux on the water side, the direct measurements of the wall temperature and saturation temperature. Tests have been performed at 40°C mean saturation temperature. The present experimental database is used to assess predictive correlations for condensation of mixtures, providing valuable information on the applicability of available models.

Evaluation of heat hyperalgesia and anxiety like-behaviors in a rat model of orofacial cancer.

PubMed

Gambeta, Eder; Kopruszinski, Caroline Machado; Dos Reis, Renata Cristiane; Zanoveli, Janaina Menezes; Chichorro, Juliana Geremias

2016-04-21

Pain and anxiety are commonly experienced by cancer patients and both significantly impair their quality of life. Some authors claim that there is a relationship between pain and anxiety, while others suggest that there is not a direct association. In any case, there is indeed a consensus that anxiety impairs the pain condition beyond be under diagnosed and undertreated in cancer pain patients. Herein we investigated if rats presenting heat hyperalgesia induced by orofacial cancer cell inoculation would display anxiety-like behaviors. In addition, we evaluated if pain blockade would result in alleviation of anxiety behaviors, as well as, if blockade of anxiety would result in pain relief. Orofacial cancer was induced in male Wistar rats by inoculation of Walker-256 cells into the right vibrissal pad. Heat facial hyperalgesia was assessed on day 6 after the inoculation, and on this time point rats were submitted to the elevated plus maze and the light-dark transition tests. The influence of lidocaine and midazolam on heat hyperalgesia and anxiety-like behaviors was assessed. The peak of facial heat hyperalgesia was detected 6 days after cancer cells inoculation, and at this time point, rats exhibited increased anxiety-like behaviors. Local treatment with lidocaine (2%/50μL) caused a marked reduction of heat hyperalgesia, but failed to affect the anxiety-like behaviors, while midazolam (0.5mg/kg, i.p.) treatment failed to change the heat threshold, but induced an anxiolytic-like effect. Altogether, our data demonstrated that rats with orofacial cancer present pain- and anxiety-like behaviors, but brief heat hyperalgesia relief does not affect the anxiety-like behaviors, and vice-versa, in our experimental conditions. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Ocean carbon and heat variability in an Earth System Model

NASA Astrophysics Data System (ADS)

Thomas, J. L.; Waugh, D.; Gnanadesikan, A.

2016-12-01

Ocean carbon and heat content are very important for regulating global climate. Furthermore, due to lack of observations and dependence on parameterizations, there has been little consensus in the modeling community on the magnitude of realistic ocean carbon and heat content variability, particularly in the Southern Ocean. We assess the differences between global oceanic heat and carbon content variability in GFDL ESM2Mc using a 500-year, pre-industrial control simulation. The global carbon and heat content are directly out of phase with each other; however, in the Southern Ocean the heat and carbon content are in phase. The global heat mutli-decadal variability is primarily explained by variability in the tropics and mid-latitudes, while the variability in global carbon content is primarily explained by Southern Ocean variability. In order to test the robustness of this relationship, we use three additional pre-industrial control simulations using different mesoscale mixing parameterizations. Three pre-industrial control simulations are conducted with the along-isopycnal diffusion coefficient (Aredi) set to constant values of 400, 800 (control) and 2400 m2 s-1. These values for Aredi are within the range of parameter settings commonly used in modeling groups. Finally, one pre-industrial control simulation is conducted where the minimum in the Gent-McWilliams parameterization closure scheme (AGM) increased to 600 m2 s-1. We find that the different simulations have very different multi-decadal variability, especially in the Weddell Sea where the characteristics of deep convection are drastically changed. While the temporal frequency and amplitude global heat and carbon content changes significantly, the overall spatial pattern of variability remains unchanged between the simulations.

Development of an inverse heat conduction model and its application to determination of heat transfer coefficient during casting solidification

NASA Astrophysics Data System (ADS)

Zhang, Liqiang; Reilly, Carl; Li, Luoxing; Cockcroft, Steve; Yao, Lu

2014-07-01

The interfacial heat transfer coefficient (IHTC) is required for the accurate simulation of heat transfer in castings especially for near net-shape processes. The large number of factors influencing heat transfer renders quantification by theoretical means a challenge. Likewise experimental methods applied directly to temperature data collected from castings are also a challenge to interpret because of the transient nature of many casting processes. Inverse methods offer a solution and have been applied successfully to predict the IHTC in many cases. However, most inverse approaches thus far focus on use of in-mold temperature data, which may be a challenge to obtain in cases where the molds are water-cooled. Methods based on temperature data from the casting have the potential to be used however; the latent heat released during the solidification of the molten metal complicates the associated IHTC calculations. Furthermore, there are limits on the maximum distance the thermocouples can be placed from the interface under analysis. An inverse conduction based method have been developed, verified and applied successfully to temperature data collected from within an aluminum casting in proximity to the mold. A modified specific heat method was used to account for latent heat evolution in which the rate of change of fraction solid with temperature was held constant. An analysis conducted with the inverse model suggests that the thermocouples must be placed no more than 2 mm from the interface. The IHTC values calculated for an aluminum alloy casting were shown to vary from 1,200 to 6,200 Wm-2 K-1. Additionally, the characteristics of the time-varying IHTC have also been discussed.

Thermal management and light extraction in multi-chip and high-voltage LEDs by cup-shaped copper heat spreader technology

NASA Astrophysics Data System (ADS)

Horng, Ray-Hua; Hu, Hung-Lieh; Tang, Li-Shen; Ou, Sin-Liang

2013-03-01

For LEDs with original structure and copper heat spreader, the highest surface temperatures of 3×3 array LEDs modules were 52.6 and 42.67 °C (with 1050 mA injection current), while the highest surface temperatures of 4×4 array LEDs modules were 58.55 and 48.85 °C (with 1400 mA injection current), respectively. As the 5×5 array LEDs modules with original structure and copper heat spreader were fabricated, the highest surface temperatures at 1750 mA injection current were 68.51 and 56.73 °C, respectively. The thermal resistance of optimal LEDs array module with copper heat spreader on heat sink using compound solder is reduced obviously. On the other hand, the output powers of 3×3, 4×4 and 5×5 array LEDs modules with original structure were 3621.7, 6346.3 and 9760.4 mW at injection currents of 1050, 1400 and 1750 mA, respectively. Meanwhile, the output powers of these samples with copper heat spreader can be improved to 4098.5, 7150.3 and 10919.6 mW, respectively. The optical and thermal characteristics of array LEDs module have been improved significantly using the cup-shaped copper structure. Furthermore, various types of epoxy-packaged LEDs with cup-shaped structure were also fabricated. It is found that the light extraction efficiency of LED with semicircle package has 55% improvement as compared to that of LED with flat package. The cup-shaped copper structure was contacted directly with sapphire to enhance heat dissipation. In addition to efficient heat dissipation, the light extraction of the lateral emitting in high-power LEDs can be improved.

The direct heat measurement of mechanical energy storage metal-organic frameworks.

PubMed

Rodriguez, Julien; Beurroies, Isabelle; Loiseau, Thierry; Denoyel, Renaud; Llewellyn, Philip L

2015-04-07

In any process, the heat exchanged is an essential property required in its development. Whilst the work related to structural transitions of some flexible metal-organic frameworks (MOFs) has been quantified and linked with potential applications such as molecular springs or shock absorbers, the heat related to such transitions has never been directly measured. This has now been carried out with MIL-53(Al) using specifically devised calorimetry experiments. We project the importance of these heats in devices such as molecular springs or dampers. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Heat treatment study 2

NASA Technical Reports Server (NTRS)

Workman, Gary L.

1990-01-01

The microstructural variations in nickel based superalloys that result from modifications in processing were examined. These superalloys include MAR-M246(HF) and PWA1480. Alternate heat treatments for equiaxed as-cast specimens were studied and a sample matrix of 42 variations in the heat treatments were processed, as well as different directional solidification parameters. Variation in temperature and times for both solution and aging were performed. Photomicrographs were made of the microstructure and volume fraction analysis of primary gamma-prime and aged gamma-prime precipitates were performed. The results of the heat treatment, cooling rate, and directional solidification experiments are discussed.

Resistively-Heated Microlith-based Adsorber for Carbon Dioxide and Trace Contaminant Removal

NASA Technical Reports Server (NTRS)

Roychoudhury, S.; Walsh, D.; Perry, J.

2005-01-01

An integrated sorber-based Trace Contaminant Control System (TCCS) and Carbon Dioxide Removal Assembly (CDRA) prototype was designed, fabricated and tested. It corresponds to a 7-person load. Performance over several adsorption/regeneration cycles was examined. Vacuum regenerations at effective time/temperature conditions, and estimated power requirements were experimentally verified for the combined CO2/trace contaminant removal prototype. The current paper details the design and performance of this prototype during initial testing at CO2 and trace contaminant concentrations in the existing CDRA, downstream of the drier. Additional long-term performance characterization is planned at NASA. Potential system design options permitting associated weight, volume savings and logistic benefits, especially as relevant for long-duration space flight, are reviewed. The technology consisted of a sorption bed with sorbent- coated metal meshes, trademarked and patented as Microlith by Precision Combustion, Inc. (PCI). By contrast the current CO2 removal system on the International Space Station employs pellet beds. Preliminary bench scale performance data (without direct resistive heating) for simultaneous CO2 and trace contaminant removal was reviewed in SAE 2004-01-2442. In the prototype, the meshes were directly electrically heated for rapid response and accurate temperature control. This allowed regeneration via resistive heating with the potential for shorter regeneration times, reduced power requirement, and net energy savings vs. conventional systems. A novel flow arrangement, for removing both CO2 and trace contaminants within the same bed, was demonstrated. Thus, the need for a separate trace contaminant unit was eliminated resulting in an opportunity for significant weight savings. Unlike the current disposable charcoal bed, zeolites for trace contaminant removal are amenable to periodic regeneration.

Reversing the Resistance Phenotype of the Biomphalaria glabrata Snail Host Schistosoma mansoni Infection by Temperature Modulation

PubMed Central

Ittiprasert, Wannaporn; Knight, Matty

2012-01-01

Biomphalaria glabrata snails that display either resistant or susceptible phenotypes to the parasitic trematode, Schistosoma mansoni provide an invaluable resource towards elucidating the molecular basis of the snail-host/schistosome relationship. Previously, we showed that induction of stress genes either after heat-shock or parasite infection was a major feature distinguishing juvenile susceptible snails from their resistant counterparts. In order to examine this apparent association between heat stress and snail susceptibility, we investigated the effect of temperature modulation in the resistant snail stock, BS-90. Here, we show that, incubated for up to 4 hrs at 32°C prior to infection, these resistant snails became susceptible to infection, i.e. shedding cercariae at 5 weeks post exposure (PE) while unstressed resistant snails, as expected, remained resistant. This suggests that susceptibility to infection by this resistant snail phenotype is temperature-sensitive (ts). Additionally, resistant snails treated with the Hsp 90 specific inhibitor, geldanamycin (GA) after heat stress, were no longer susceptible to infection, retaining their resistant phenotype. Consistently, susceptible snail phenotypes treated with 100 mM GA before parasite exposure also remained uninfected. These results provide direct evidence for the induction of stress genes (heat shock proteins; Hsp 70, Hsp 90 and the reverse transcriptase [RT] domain of the nimbus non-LTR retrotransposon) in B. glabrata susceptibility to S. mansoni infection and characterize the resistant BS-90 snails as a temperature-sensitive phenotype. This study of reversing snail susceptibility phenotypes to S. mansoni provides an opportunity to directly track molecular pathway(s) that underlie the B. glabrata snail's ability to either sustain or destroy the S. mansoni parasite. PMID:22577362

Reversing the resistance phenotype of the Biomphalaria glabrata snail host Schistosoma mansoni infection by temperature modulation.

PubMed

Ittiprasert, Wannaporn; Knight, Matty

2012-01-01

Biomphalaria glabrata snails that display either resistant or susceptible phenotypes to the parasitic trematode, Schistosoma mansoni provide an invaluable resource towards elucidating the molecular basis of the snail-host/schistosome relationship. Previously, we showed that induction of stress genes either after heat-shock or parasite infection was a major feature distinguishing juvenile susceptible snails from their resistant counterparts. In order to examine this apparent association between heat stress and snail susceptibility, we investigated the effect of temperature modulation in the resistant snail stock, BS-90. Here, we show that, incubated for up to 4 hrs at 32°C prior to infection, these resistant snails became susceptible to infection, i.e. shedding cercariae at 5 weeks post exposure (PE) while unstressed resistant snails, as expected, remained resistant. This suggests that susceptibility to infection by this resistant snail phenotype is temperature-sensitive (ts). Additionally, resistant snails treated with the Hsp 90 specific inhibitor, geldanamycin (GA) after heat stress, were no longer susceptible to infection, retaining their resistant phenotype. Consistently, susceptible snail phenotypes treated with 100 mM GA before parasite exposure also remained uninfected. These results provide direct evidence for the induction of stress genes (heat shock proteins; Hsp 70, Hsp 90 and the reverse transcriptase [RT] domain of the nimbus non-LTR retrotransposon) in B. glabrata susceptibility to S. mansoni infection and characterize the resistant BS-90 snails as a temperature-sensitive phenotype. This study of reversing snail susceptibility phenotypes to S. mansoni provides an opportunity to directly track molecular pathway(s) that underlie the B. glabrata snail's ability to either sustain or destroy the S. mansoni parasite.

Ground and Satellite Observations of ULF Waves Artificially Produced by HAARP

NASA Astrophysics Data System (ADS)

Chang, C.; Labenski, J.; Shroff, H.; Doxas, I.; Papadopoulos, D.; Milikh, G.; Parrot, M.

2008-12-01

Modulated ionospheric heating at ULF frequencies using the HAARP heater was performed from April 28 to May 3, 2008 (http://www.haarp.alaska.edu). Simultaneous ground-based ULF measurements were made locally at Gakona, AK and at Lake Ozette, WA that is 2000 km away. The ground-based results showed that ULF amplitudes measured at Gakona are mostly proportional to the electrojet strength above HAARP, indicating electrojet modulation to be the source of the local ULF waves. However, the timing of ULF events recorded at Lake Ozette did not correlated with the electrojet strength at Gakona, indicating that modulation of F region pressure is the more likely source for distant ULF waves. These observations are consistent with the theoretical understanding that ULF waves generated by current modulation are shear Alfven waves propagating along the magnetic field line, thus at high latitude their observations are limited to the vicinity of the heated spot. On the other hand, propagation of ULF waves at significant lateral distances requires generation of magnetosonic waves since they are the only mode that propagates isotropically and can thus couple efficiently in the Alfvenic duct. In addition to ground-based observations, the DEMETER satellite also provided space measurements of the heating effects during its passes over HAARP. The DEMETER results showed direct detection of HAARP ULF waves at 0.1 Hz. Moreover, density dips were observed every time HAARP was operated at CW mode, which provides clear evidence of duct formation by direct HF heating at F peak. Details of these results will be presented at the meeting. We would like to acknowledge the support provided by the HAARP facility during our ULF experiments.

40 CFR 63.601 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... part 60, appendix A, Method 5. Phosphate rock calciner means the equipment used to remove moisture and organic matter from phosphate rock through direct or indirect heating. Phosphate rock dryer means the equipment used to reduce the moisture content of phosphate rock through direct or indirect heating...

40 CFR 63.601 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... part 60, appendix A, Method 5. Phosphate rock calciner means the equipment used to remove moisture and organic matter from phosphate rock through direct or indirect heating. Phosphate rock dryer means the equipment used to reduce the moisture content of phosphate rock through direct or indirect heating...

Reconciling estimates of the ratio of heat and salt fluxes at the ice-ocean interface

NASA Astrophysics Data System (ADS)

Keitzl, T.; Mellado, J. P.; Notz, D.

2016-12-01

The heat exchange between floating ice and the underlying ocean is determined by the interplay of diffusive fluxes directly at the ice-ocean interface and turbulent fluxes away from it. In this study, we examine this interplay through direct numerical simulations of free convection. Our results show that an estimation of the interface flux ratio based on direct measurements of the turbulent fluxes can be difficult because the flux ratio varies with depth. As an alternative, we present a consistent evaluation of the flux ratio based on the total heat and salt fluxes across the boundary layer. This approach allows us to reconcile previous estimates of the ice-ocean interface conditions. We find that the ratio of heat and salt fluxes directly at the interface is 83-100 rather than 33 as determined by previous turbulence measurements in the outer layer. This can cause errors in the estimated ice-ablation rate from field measurements of up to 40% if they are based on the three-equation formulation.

Inducing Stable α + β Microstructures during Selective Laser Melting of Ti-6Al-4V Using Intensified Intrinsic Heat Treatments

PubMed Central

Barriobero-Vila, Pere; Gussone, Joachim; Haubrich, Jan; Sandlöbes, Stefanie; Da Silva, Julio Cesar; Cloetens, Peter; Schell, Norbert; Requena, Guillermo

2017-01-01

Selective laser melting is a promising powder-bed-based additive manufacturing technique for titanium alloys: near net-shaped metallic components can be produced with high resource-efficiency and cost savings. For the most commercialized titanium alloy, namely Ti-6Al-4V, the complicated thermal profile of selective laser melting manufacturing (sharp cycles of steep heating and cooling rates) usually hinders manufacturing of components in a one-step process owing to the formation of brittle martensitic microstructures unsuitable for structural applications. In this work, an intensified intrinsic heat treatment is applied during selective laser melting of Ti-6Al-4V powder using a scanning strategy that combines porosity-optimized processing with a very tight hatch distance. Extensive martensite decomposition providing a uniform, fine lamellar α + β microstructure is obtained along the building direction. Moreover, structural evidence of the formation of the intermetallic α2-Ti3Al phase is provided. Variations in the lattice parameter of β serve as an indicator of the microstructural degree of stabilization. Interconnected 3D networks of β are generated in regions highly affected by the intensified intrinsic heat treatment applied. The results obtained reflect a contribution towards simultaneous selective laser melting-manufacturing and heat treatment for fabrication of Ti-6Al-4V parts. PMID:28772630

How do Stability Corrections Perform in the Stable Boundary Layer Over Snow?

NASA Astrophysics Data System (ADS)

Schlögl, Sebastian; Lehning, Michael; Nishimura, Kouichi; Huwald, Hendrik; Cullen, Nicolas J.; Mott, Rebecca

2017-10-01

We assess sensible heat-flux parametrizations in stable conditions over snow surfaces by testing and developing stability correction functions for two alpine and two polar test sites. Five turbulence datasets are analyzed with respect to, (a) the validity of the Monin-Obukhov similarity theory, (b) the model performance of well-established stability corrections, and (c) the development of new univariate and multivariate stability corrections. Using a wide range of stability corrections reveals an overestimation of the turbulent sensible heat flux for high wind speeds and a generally poor performance of all investigated functions for large temperature differences between snow and the atmosphere above (>10 K). Applying the Monin-Obukhov bulk formulation introduces a mean absolute error in the sensible heat flux of 6 W m^{-2} (compared with heat fluxes calculated directly from eddy covariance). The stability corrections produce an additional error between 1 and 5 W m^{-2}, with the smallest error for published stability corrections found for the Holtslag scheme. We confirm from previous studies that stability corrections need improvements for large temperature differences and wind speeds, where sensible heat fluxes are distinctly overestimated. Under these atmospheric conditions our newly developed stability corrections slightly improve the model performance. However, the differences between stability corrections are typically small when compared to the residual error, which stems from the Monin-Obukhov bulk formulation.

Thermal heat-balance mode flow-to-frequency converter

NASA Astrophysics Data System (ADS)

Pawlowski, Eligiusz

2016-11-01

This paper presents new type of thermal flow converter with the pulse frequency output. The integrating properties of the temperature sensor have been used, which allowed for realization of pulse frequency modulator with thermal feedback loop, stabilizing temperature of sensor placed in the flowing medium. The system assures balancing of heat amount supplied in impulses to the sensor and heat given up by the sensor in a continuous way to the flowing medium. Therefore the frequency of output impulses is proportional to the heat transfer coefficient from sensor to environment. According to the King's law, the frequency of those impulses is a function of medium flow velocity around the sensor. The special feature of presented solution is total integration of thermal sensor with the measurement signal conditioning system. Sensor and conditioning system are not the separate elements of the measurement circuit, but constitute a whole in form of thermal heat-balance mode flow-to-frequency converter. The advantage of such system is easiness of converting the frequency signal to the digital form, without using any additional analogue-to-digital converters. The frequency signal from the converter may be directly connected to the microprocessor input, which with use of standard built-in counters may convert the frequency into numerical value of high precision. Moreover, the frequency signal has higher resistance to interference than the voltage signal and may be transmitted to remote locations without the information loss.

A laboratory exercise using a physical model for demonstrating countercurrent heat exchange.

PubMed

Loudon, Catherine; Davis-Berg, Elizabeth C; Botz, Jason T

2012-03-01

A physical model was used in a laboratory exercise to teach students about countercurrent exchange mechanisms. Countercurrent exchange is the transport of heat or chemicals between fluids moving in opposite directions separated by a permeable barrier (such as blood within adjacent blood vessels flowing in opposite directions). Greater exchange of heat or chemicals between the fluids occurs when the flows are in opposite directions (countercurrent) than in the same direction (concurrent). When a vessel loops back on itself, countercurrent exchange can occur between the two arms of the loop, minimizing loss or uptake at the bend of the loop. Comprehension of the physical principles underlying countercurrent exchange helps students to understand how kidneys work and how modifications of a circulatory system can influence the movement of heat or chemicals to promote or minimize exchange and reinforces the concept that heat and chemicals move down their temperature or concentration gradients, respectively. One example of a well-documented countercurrent exchanger is the close arrangement of veins and arteries inside bird legs; therefore, the setup was arranged to mimic blood vessels inside a bird leg, using water flowing inside tubing as a physical proxy for blood flow within blood vessels.

Short communication: Implementation of a breeding value for heat tolerance in Australian dairy cattle.

PubMed

Nguyen, Thuy T T; Bowman, Phil J; Haile-Mariam, Mekonnen; Nieuwhof, Gert J; Hayes, Benjamin J; Pryce, Jennie E

2017-09-01

Excessive ambient temperature and humidity can impair milk production and fertility of dairy cows. Selection for heat-tolerant animals is one possible option to mitigate the effects of heat stress. To enable selection for this trait, we describe the development of a heat tolerance breeding value for Australian dairy cattle. We estimated the direct genomic values of decline in milk, fat, and protein yield per unit increase of temperature-humidity index (THI) using 46,726 single nucleotide polymorphisms and a reference population of 2,236 sires and 11,853 cows for Holsteins and 506 sires and 4,268 cows for Jerseys. This new direct genomic value is the Australian genomic breeding value for heat tolerance (HT ABVg). The components of the HT ABVg are the decline in milk, fat, and protein per unit increase in THI when THI increases above the threshold of 60. These components are weighted by their respective economic values, assumed to be equivalent to the weights applied to milk, fat, and protein yield in the Australian selection indices. Within each breed, the HT ABVg is then standardized to have a mean of 100 and standard deviation (SD) of 5, which is consistent with the presentation of breeding values for many other traits in Australia. The HT ABVg ranged from -4 to +3 SD in Holsteins and -3 to +4 SD in Jerseys. The mean reliabilities of HT ABVg among validation sires, calculated from the prediction error variance and additive genetic variance, were 38% in both breeds. The range in ABVg and their reliability suggests that HT can be improved using genomic selection. There has been a deterioration in the genetic trend of HT, and to moderate the decline it is suggested that the HT ABVg should be included in a multitrait economic index with other traits that contribute to farm profit. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

[Climate change - physical and mental consequences].

PubMed

Bunz, Maxie; Mücke, Hans-Guido

2017-06-01

Climate change has already had a large influence on the human environmental system and directly or indirectly affects physical and mental health. Triggered by extreme meteorological conditions, for example, storms, floods, earth slides and heat periods, the direct consequences range from illnesses to serious accidents with injuries, or in extreme cases fatalities. Indirectly, a changed environment due to climate change affects, amongst other things, the cardiovascular system and respiratory tract, and can also cause allergies and infectious diseases. In addition, increasing confrontation with environmental impacts may cause negative psychological effects such as posttraumatic stress disorders and anxiety, but also aggression, distress and depressive symptoms. The extent and severity of the health consequences depend on individual pre-disposition, resilience, behaviour and adaptation.

Development and thermal management of 10 kW CW, direct diode laser source

NASA Astrophysics Data System (ADS)

Zhu, Hongbo; Hao, Mingming; Zhang, Jianwei; Ji, Wenyu; Lin, Xingchen; Zhang, Jinsheng; Ning, Yongqiang

2016-01-01

We report on the development of direct diode laser source with high-power and high reliability. The laser source was realized by the polarization and wavelength combination of four diode laser stacks. When at the operating current of 122 A, the source was capable of producing 10,120 W output while maintaining 46% electro-optical conversion efficiency. The maximum temperature on the lens was decreased from 442.2 K to 320 K by utilizing an efficient thermal dissipation structure, and the corresponding maximum von Mises stress was reduced from 75.4 MPa to 14 MPa. In addition, a reliability test demonstrated that our laser source was reliable and potential in the applications of laser cladding and heat treatment.

Application of Surface Protective Coating to Enhance Environment-Withstanding Property of the MEMS 2D Wind Direction and Wind Speed Sensor.

PubMed

Shin, Kyu-Sik; Lee, Dae-Sung; Song, Sang-Woo; Jung, Jae Pil

2017-09-19

In this study, a microelectromechanical system (MEMS) two-dimensional (2D) wind direction and wind speed sensor consisting of a square heating source and four thermopiles was manufactured using the heat detection method. The heating source and thermopiles of the manufactured sensor must be exposed to air to detect wind speed and wind direction. Therefore, there are concerns that the sensor could be contaminated by deposition or adhesion of dust, sandy dust, snow, rain, and so forth, in the air, and that the membrane may be damaged by physical shock. Hence, there was a need to protect the heating source, thermopiles, and the membrane from environmental and physical shock. The upper protective coating to protect both the heating source and thermopiles and the lower protective coating to protect the membrane were formed by using high-molecular substances such as SU-8, Teflon and polyimide (PI). The sensor characteristics with the applied protective coatings were evaluated.

Evaluation of Computational Fluid Dynamics and Coupled Fluid-Solid Modeling for a Direct Transfer Preswirl System.

PubMed

Javiya, Umesh; Chew, John; Hills, Nick; Dullenkopf, Klaus; Scanlon, Timothy

2013-05-01

The prediction of the preswirl cooling air delivery and disk metal temperature are important for the cooling system performance and the rotor disk thermal stresses and life assessment. In this paper, standalone 3D steady and unsteady computation fluid dynamics (CFD), and coupled FE-CFD calculations are presented for prediction of these temperatures. CFD results are compared with previous measurements from a direct transfer preswirl test rig. The predicted cooling air temperatures agree well with the measurement, but the nozzle discharge coefficients are under predicted. Results from the coupled FE-CFD analyses are compared directly with thermocouple temperature measurements and with heat transfer coefficients on the rotor disk previously obtained from a rotor disk heat conduction solution. Considering the modeling limitations, the coupled approach predicted the solid metal temperatures well. Heat transfer coefficients on the rotor disk from CFD show some effect of the temperature variations on the heat transfer coefficients. Reasonable agreement is obtained with values deduced from the previous heat conduction solution.

On the toughness scatter in low alloy C-Mn steel samples fabricated using wire arc additive manufacturing

DOE PAGES

Sridharan, Niyanth S.; Noakes, Mark W.; Nycz, Andrzej; ...

2017-12-06

Low alloy carbon manganese (C-Mn) steel builds were fabricated using a wire based additive manufacturing system developed at Oak Ridge National Laboratory. Specimens were fabricated in the X,Y and Z direction and detailed mechanical testing was performed. The mechanical testing results showed a significant scatter in tensile ductility and significant variation in Charpy toughness. Further detailed microstructure characterization showed significant microstructural heterogeneity in builds fabricated in each direction. The scatter in mechanical properties was then rationalized based on the microstructural observations and the underlying changes in the local heat transfer conditions. Lastly, the results indicate that when fabricating parts usingmore » C-Mn low alloy steel welds the process parameters and tool path should be chosen such that the cooling rate from 800 °C to 500 °C is greater than 30 s to avoid formation of martensite austenite (MA) phases, which leads to toughness reductions.« less

On the toughness scatter in low alloy C-Mn steel samples fabricated using wire arc additive manufacturing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sridharan, Niyanth S.; Noakes, Mark W.; Nycz, Andrzej

Low alloy carbon manganese (C-Mn) steel builds were fabricated using a wire based additive manufacturing system developed at Oak Ridge National Laboratory. Specimens were fabricated in the X,Y and Z direction and detailed mechanical testing was performed. The mechanical testing results showed a significant scatter in tensile ductility and significant variation in Charpy toughness. Further detailed microstructure characterization showed significant microstructural heterogeneity in builds fabricated in each direction. The scatter in mechanical properties was then rationalized based on the microstructural observations and the underlying changes in the local heat transfer conditions. Lastly, the results indicate that when fabricating parts usingmore » C-Mn low alloy steel welds the process parameters and tool path should be chosen such that the cooling rate from 800 °C to 500 °C is greater than 30 s to avoid formation of martensite austenite (MA) phases, which leads to toughness reductions.« less

Shear deformation-induced anisotropic thermal conductivity of graphene.

PubMed

Cui, Liu; Shi, Sanqiang; Wei, Gaosheng; Du, Xiaoze

2018-01-03

Graphene-based materials exhibit intriguing phononic and thermal properties. In this paper, we have investigated the heat conductance in graphene sheets under shear-strain-induced wrinkling deformation, using equilibrium molecular dynamics simulations. A significant orientation dependence of the thermal conductivity of graphene wrinkles (GWs) is observed. The directional dependence of the thermal conductivity of GWs stems from the anisotropy of phonon group velocities as revealed by the G-band broadening of the phonon density of states (DOS), the anisotropy of thermal resistance as evidenced by the G-band peak mismatch of the phonon DOS, and the anisotropy of phonon relaxation times as a direct result of the double-exponential-fitting of the heat current autocorrelation function. By analyzing the relative contributions of different lattice vibrations to the heat flux, we have shown that the contributions of different lattice vibrations to the heat flux of GWs are sensitive to the heat flux direction, which further indicates the orientation-dependent thermal conductivity of GWs. Moreover, we have found that, in the strain range of 0-0.1, the anisotropy ratio of GWs increases monotonously with increasing shear strain. This is induced by the change in the number of wrinkles, which is more influential in the direction perpendicular to the wrinkle texture. The findings elucidated here emphasize the utility of wrinkle engineering for manipulation of nanoscale heat transport, which offers opportunities for the development of thermal channeling devices.

Exterior direct view of (nonoriginal), solar heating panels, and top ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Exterior direct view of (non-original), solar heating panels, and top of typical rectangular trash-dump tower at roof of Building 6, looking north - North Beach Place, 401 Bay Street, 500 Francisco Street, 401 Bay Street, 500 Francisco Street, San Francisco, San Francisco County, CA

High-temperature zirconia insulation and method for making same

DOEpatents

Wrenn, G.E. Jr.; Holcombe, C.E. Jr.; Lewis, J. Jr.

1988-05-10

The present invention is directed to a highly pure, partially stabilized, fibrous zirconia composite for use as thermal insulation in environments where temperatures up to about 2,000 C are utilized. The composite of the present invention is fabricated into any suitable configuration such as a cone, cylinder, dome or the like by vacuum molding an aqueous slurry of partially stabilized zirconia fibers into a desired configuration on a suitably shaped mandrel. The molded fibers are infiltrated with zirconyl nitrate and the resulting structure is then dried to form a rigid structure which may be removed and placed in a furnace. The structure is then heated in air to a temperature of about 600 C for driving off the nitrate from the structure and for oxidizing the zirconyl ion to zirconia. Thereafter, the structure is heated to about 950 to 1,250 C to fuse the zirconia fibers at their nexi in a matrix of zirconia. The composite produced by the present invention is self-supporting and can be readily machined to desired final dimensions. Additional heating to about 1,800 to 2,000 C further improves structural rigidity.

Effect of pH, Surfactant, and Heat Treatment on Morphology, Structure, and Hardness of Electrodeposited Co-P Coatings

NASA Astrophysics Data System (ADS)

Zeinali-Rad, M.; Allahkaram, S. R.; Mahdavi, S.

2015-09-01

Nano-crystalline and amorphous Co-P coatings were deposited on plain carbon steel substrates by using direct current. Effects of electrolyte pH on morphology, current efficiency, phosphorus content, hardness, and preferred orientation of the nano-crystalline coatings were investigated. Moreover, the effects of heat treatment on microstructure and hardness of the nano-crystalline and the amorphous coatings were studied. The results showed that, phosphorus content and hardness of the nano-crystalline coatings were decreased by increasing of the pH, in spite of a current efficiency enhancement to as much as 98%. Grain size and preferred orientation were also changed from 13 to 31 nm and from mostly [002] to [100] by increasing the pH from 1 to 4, respectively. Smoother coatings and higher current efficiencies were obtained by the addition of 1 g/L sodium dodecyl sulfate (SDS) to the bath. Highest hardness of the nano-crystalline and the amorphous coatings was about 600 and 750 HV, which increased and reached 760 and 1090 HV after heat treatment, respectively.

Uncertainty contribution on the density of liquids due to unknown sinker temperature in hydrostatic weighing apparatus

NASA Astrophysics Data System (ADS)

Schiebl, M.; Zelenka, Z.; Buchner, C.; Pohl, R.; Steindl, D.

2018-02-01

In this study, the influence of the unknown sinker temperature on the measured density of liquids is evaluated. Generally, due to the intrinsic temperature instability of the heat bath temperature controller, the system will never reach thermal equilibrium but instead will oscillate around a mean temperature. The sinker temperature follows this temperature oscillation with a certain time lag. Since the sinker temperature is not measured directly in a hydrostatic weighing apparatus, the temperature of the sinker, and thus in turn the volume of the sinker, is not known exactly. As a consequence, this leads to uncertainty in the value of the density of the liquid. From an analysis of the volume relaxation of the sinker immersed into a heat bath with time-dependent temperature characteristics, the heat transfer coefficient can be estimated, and thus a characteristic time constant for achieving quasi thermal equilibrium for a hydrostatic weighing apparatus is proposed. Additionally, from a theoretical analysis of the transient behavior of the sinker volume, the systematic deviation of the theoretical to the actual measured liquid density is calculated.

Identifying the critical point of the weakly first-order itinerant magnet DyCo2 with complementary magnetization and calorimetric measurements

NASA Astrophysics Data System (ADS)

Morrison, K.; Dupas, A.; Mudryk, Y.; Pecharsky, V. K.; Gschneidner, K. A.; Caplin, A. D.; Cohen, L. F.

2013-04-01

We examine the character of the itinerant magnetic transition of DyCo2 by different calorimetric methods, thereby separating the heat capacity and latent heat contributions to the entropy—allowing direct comparison to other itinerant electron metamagnetic systems. The heat capacity exhibits a large λ-like peak at the ferrimagnetic ordering phase transition, a signature that is remarkably similar to La(Fe,Si)13, where it is attributed to giant spin fluctuations. Using calorimetric measurements, we also determine the point at which the phase transition ceases to be first order: the critical magnetic field, μ0Hcrit = 0.4 ± 0.1 T and temperature Tcrit = 138.5 ± 0.5 K, and we compare these values to those obtained from analysis of magnetization by application of the Shimizu inequality for itinerant electron metamagnetism. Good agreement is found between these independent measurements, thus establishing the phase diagram and critical point with some confidence. In addition, we find that the often-used Banerjee criterion may not be suitable for determination of first order behavior in itinerant magnet systems.

Mass spectrometric analysis of organic compounds, water and volatile constituents in the atmosphere and surface of Mars - The Viking Mars Lander.

NASA Technical Reports Server (NTRS)

Anderson, D. M.; Biemann, K.; Orgel, L. E.; Oro, J.; Owen , T.; Shulman, G. P.; Toulmin, P., III; Urey, H. C.

1972-01-01

An experiment centering around a mass spectrometer is described, which is aimed at the identification of organic substances present in the top 10 cm of the surface of Mars and an analysis of the atmosphere for major and minor constituents as well as isotopic abundances. In addition, an indication of the abundance of water in the surface and some information concerning the mineralogy can be obtained by monitoring the gases produced upon heating the soil sample. The organic material will simply be expelled by heating to 150, 300, and 500 C into the carrier gas stream of a gas chromatograph interfaced to the mass spectrometer or by slowly heating the sample in direct communication with the spectrometer. It is planned to analyze a total of up to nine soil samples in order to study diurnal and seasonal variations. The system is designed to give useful data even for minor constituents if the total of organics should be as low as 5 ppm. The spectrometer covers the mass range of 12-200 with adequate resolution.

Configuration of dishwasher to improve energy efficiency of water heating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gluesenkamp, Kyle R.

A washing machine includes a sealed tub for accepting articles to be washed. A liquid circulation circuit sprays a pressurized liquid (e.g. water, detergent, solvent) around the articles to clean them. The liquid circulation circuit is in thermal contact with a hot side of a thermoelectric device. A heat sink is in thermal contact with both a cold side of the thermoelectric device and a heat sink charging circuit. A liquid is successively directed one or more times through the liquid circulation circuit with the thermoelectric device powered on, and then directed one or more times through the heat sinkmore » charging circuit with the thermoelectric device powered off. Finally, the liquid is discharged from the tub after having its temperature lowered by heat exchange to the heat sink.« less

Circulating heat exchangers for oscillating wave engines and refrigerators

DOEpatents

Swift, Gregory W.; Backhaus, Scott N.

2003-10-28

An oscillating-wave engine or refrigerator having a regenerator or a stack in which oscillating flow of a working gas occurs in a direction defined by an axis of a trunk of the engine or refrigerator, incorporates an improved heat exchanger. First and second connections branch from the trunk at locations along the axis in selected proximity to one end of the regenerator or stack, where the trunk extends in two directions from the locations of the connections. A circulating heat exchanger loop is connected to the first and second connections. At least one fluidic diode within the circulating heat exchanger loop produces a superimposed steady flow component and oscillating flow component of the working gas within the circulating heat exchanger loop. A local process fluid is in thermal contact with an outside portion of the circulating heat exchanger loop.

Defense Small Business Innovation Research Program (SBIR) Abstracts of Phase I Awards 1984.

DTIC Science & Technology

1985-04-16

PROTECTION OF SATELLITES FROM DIRECTED ENERGY WEAPONS, IS THE UTILIZATION OF HEAT PIPES WITHIN A SHIELD STRUCTURE. HEAT PIPES COULD BE DESIGNED TO...780 EDEN ROAD LANCASTER, PA 17601 ROBERT M. SHAUBACK TITLE: ANALYSIS AND PERFORMNCE EVALUATION OF HEAT PIPES WITH MULTIPLE HEAT SOURCES TOPIC: 97... PIPES CAPABLE OF ACCEPTING HEAT FROM MULTIPLE HEAT SOURCES. THERE IS NO THOROUGH ANALYTICAL OR EXPERIMENTAL BASIS FOR THE DESIGN OF HEAT PIPES OF

Thermal modelling and control of 130kw direct contact (salt/air) heat exchanger

NASA Astrophysics Data System (ADS)

Qureshi, Omer A.; Calvet, Nicolas; Armstrong, Peter R.

2017-06-01

This work investigates the transient response of a certain type of direct contact heat exchanger (DCHX) that consists of packing (Raschig Rings) to increase the surface area for effective heat transfer between molten salt and air. Molten salt from the hot tank enters the heat exchanger (HX) and exit after heating the air still in the molten form. Thermal capacitance of the HX, mainly due to packing and resident salt inside the HX, results in strong transient response. Pure delay from salt residence time may also impact transient response. Both phenomena have been modelled in this paper. A Proportional-Integral controller (PI control) performance has been evaluated to maintain the minimum salt temperature above avoid crystallization temperature of the salt.

Consolidation of lunar regolith: Microwave versus direct solar heating

NASA Technical Reports Server (NTRS)

Kunitzer, J.; Strenski, D. G.; Yankee, S. J.; Pletka, B. J.

1991-01-01

The production of construction materials on the lunar surface will require an appropriate fabrication technique. Two processing methods considered as being suitable for producing dense, consolidated products such as bricks are direct solar heating and microwave heating. An analysis was performed to compare the two processes in terms of the amount of power and time required to fabricate bricks of various size. The regolith was considered to be a mare basalt with an overall density of 60 pct. of theoretical. Densification was assumed to take place by vitrification since this process requires moderate amounts of energy and time while still producing dense products. Microwave heating was shown to be significantly faster compared to solar furnace heating for rapid production of realistic-size bricks.

Heat-flow equation motivated by the ideal-gas shock wave.

PubMed

Holian, Brad Lee; Mareschal, Michel

2010-08-01

We present an equation for the heat-flux vector that goes beyond Fourier's Law of heat conduction, in order to model shockwave propagation in gases. Our approach is motivated by the observation of a disequilibrium among the three components of temperature, namely, the difference between the temperature component in the direction of a planar shock wave, versus those in the transverse directions. This difference is most prominent near the shock front. We test our heat-flow equation for the case of strong shock waves in the ideal gas, which has been studied in the past and compared to Navier-Stokes solutions. The new heat-flow treatment improves the agreement with nonequilibrium molecular-dynamics simulations of hard spheres under strong shockwave conditions.

Heat transfer analysis of a lab scale solar receiver using the discrete ordinates model

NASA Astrophysics Data System (ADS)

Dordevich, Milorad C. W.

This thesis documents the development, implementation and simulation outcomes of the Discrete Ordinates Radiation Model in ANSYS FLUENT simulating the radiative heat transfer occurring in the San Diego State University lab-scale Small Particle Heat Exchange Receiver. In tandem, it also serves to document how well the Discrete Ordinates Radiation Model results compared with those from the in-house developed Monte Carlo Ray Trace Method in a number of simplified geometries. The secondary goal of this study was the inclusion of new physics, specifically buoyancy. Implementation of an additional Monte Carlo Ray Trace Method software package known as VEGAS, which was specifically developed to model lab scale solar simulators and provide directional, flux and beam spread information for the aperture boundary condition, was also a goal of this study. Upon establishment of the model, test cases were run to understand the predictive capabilities of the model. It was shown that agreement within 15% was obtained against laboratory measurements made in the San Diego State University Combustion and Solar Energy Laboratory with the metrics of comparison being the thermal efficiency and outlet, wall and aperture quartz temperatures. Parametric testing additionally showed that the thermal efficiency of the system was very dependent on the mass flow rate and particle loading. It was also shown that the orientation of the small particle heat exchange receiver was important in attaining optimal efficiency due to the fact that buoyancy induced effects could not be neglected. The analyses presented in this work were all performed on the lab-scale small particle heat exchange receiver. The lab-scale small particle heat exchange receiver is 0.38 m in diameter by 0.51 m tall and operated with an input irradiation flux of 3 kWth and a nominal mass flow rate of 2 g/s with a suspended particle mass loading of 2 g/m3. Finally, based on acumen gained during the implementation and development of the model, a new and improved design was simulated to predict how the efficiency within the small particle heat exchange receiver could be improved through a few simple internal geometry design modifications. It was shown that the theoretical calculated efficiency of the small particle heat exchange receiver could be improved from 64% to 87% with adjustments to the internal geometry, mass flow rate, and mass loading.

The HumanIndexMod and New Calculations Demonstrating Heat Stress Effects All Aspects of Human Life Through Industry, Agriculture, and Daily Life.

NASA Astrophysics Data System (ADS)

Buzan, J. R.; Huber, M.

2014-12-01

We show the new climatic tool, HumanIndexMod (HIM), for quantitatively assessing key climatic variables that are critical for decision making. The HIM calculates 9 different heat stress and 4 moist thermodynamic quantities using meteorological inputs of T, P, and Q. These heat stress metrics are commonly used throughout the world. We show new methods for integrating and standardizing practices for applying these metrics with the latest Earth system models. We implemented the HIM into CLM4.5, a component of CESM, maintained by NCAR. These heat stress metrics cover philosophical approaches of comfort, physiology, and empirically based algorithms. The metrics are directly connected to the Urban, Canopy, Bare Ground, and Lake modules, to differentiate distinct regimes within each grid cell. The module calculates the instantaneous moisture-temperature covariance at every model time step and in every land surface type, capturing all aspects of non-linearity. The HIM uses the most accurate and computationally efficient moist thermodynamic algorithms available. Additionally, we show ways that the HIM may be effectively integrated into climate modeling and observations. The module is flexible. The user may decide which metrics to call, and there is an offline version of the HIM that is available to be used with weather and climate datasets. Examples include using high temporal resolution CMIP5 archive data, local weather station data, and weather and forecasting models. To provide comprehensive standards for applying the HIM to climate data, we executed a CLM4.5 simulation using the RCP8.5 boundary conditions. Preliminary results show moist thermodynamic and heat stress quantities have smaller variability in the extremes as compared to extremes in T (both at the 95th percentile). Additionally, the magnitude of the moist thermodynamic changes over land is similar to sea surface temperature changes. The metric changes from the early part of the 21st century as compared to the end of the 21st century show that many portions of the world switch from moderate levels of heat stress for the top 2 weeks of a year to severe heat stress for the top 2 weeks of a year. These changes are reflected in livestock (THI); evaporative cooling (SWMP80) and air-conditioning; and industrial, military, and athletic heat stress (sWBGT, DI, HI, etc.).

Thermal-Diode Sandwich Panel

NASA Technical Reports Server (NTRS)

Basiulis, A.

1986-01-01

Thermal diode sandwich panel transfers heat in one direction, but when heat load reversed, switches off and acts as thermal insulator. Proposed to control temperature in spacecraft and in supersonic missiles to protect internal electronics. In combination with conventional heat pipes, used in solar panels and other heat-sensitive systems.

46 CFR 151.40-1 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-10-01

... lower energy vapor or its condensate returned to the tank. (2) External heat exchange. A refrigeration... heat exchanger. Refrigeration is not accomplished by direct compression of the cargo. (c) Internal heat exchange. A refrigeration system in which a cooling fluid is passed through heat transfer coils immersed in...

46 CFR 151.40-1 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... lower energy vapor or its condensate returned to the tank. (2) External heat exchange. A refrigeration... heat exchanger. Refrigeration is not accomplished by direct compression of the cargo. (c) Internal heat exchange. A refrigeration system in which a cooling fluid is passed through heat transfer coils immersed in...

46 CFR 151.40-1 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-10-01

... lower energy vapor or its condensate returned to the tank. (2) External heat exchange. A refrigeration... heat exchanger. Refrigeration is not accomplished by direct compression of the cargo. (c) Internal heat exchange. A refrigeration system in which a cooling fluid is passed through heat transfer coils immersed in...

46 CFR 151.40-1 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... lower energy vapor or its condensate returned to the tank. (2) External heat exchange. A refrigeration... heat exchanger. Refrigeration is not accomplished by direct compression of the cargo. (c) Internal heat exchange. A refrigeration system in which a cooling fluid is passed through heat transfer coils immersed in...

46 CFR 151.40-1 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-10-01

... lower energy vapor or its condensate returned to the tank. (2) External heat exchange. A refrigeration... heat exchanger. Refrigeration is not accomplished by direct compression of the cargo. (c) Internal heat exchange. A refrigeration system in which a cooling fluid is passed through heat transfer coils immersed in...

40 CFR 63.981 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... an enclosed combustion device that transfers heat liberated by burning fuel directly to process streams or to heat transfer liquids other than water. A process heater may, as a secondary function, heat... means gases that are combusted to derive useful work or heat. Fuel gas system means the offsite and...

An Innovative Very Low Thermal Power Waste Heat Recovery System for Thermal Control of Deep Space Missions: A Thermal Flask in Space

NASA Technical Reports Server (NTRS)

Bhandari, Pradeep

2015-01-01

Future missions to deep space, such as those to the outer planets (Jupiter, Saturn, etc.), which would rely on solar photovoltaic power, would need extremely large solar arrays to produce sufficient power for their operations because solar intensity is so low at those locations. Hence any additional power that would be needed for thermal control is extremely limited. Previous deep space missions like Juno (to Jupiter) required almost 200 W of electrical power for thermal control. This is prohibitively large for many future mission concepts, and leads to them needing very large solar arrays. For Saturn, where the solar flux is 1/4th the flux at Jupiter, this would entail an extremely large increase in the solar array size to accommodate the need for thermal survival power, which would be prohibitively large in size and mass, and very expensive. Hence there is a need to come up with a thermal architecture and design options that would not need such prohibitively large thermal power levels. One solution relies on harvesting the pre-existing waste heat from all the heat dissipation that would be present from operation of electronics, instruments, etc. for their own functionality. For example, for a generic Saturn mission, the various electronics would already dissipate about 200 Watts of heat that is simply "thrown away" to space from the spacecraft surfaces. The amount of thermal power that would be required for the safe thermal control of components within the spacecraft in deep space would be roughly of this magnitude for this class of spacecraft. So it makes good sense to try to harvest the waste heat and employ it to maintain the temperatures of all the components within their allowable limits. In particular, propulsion systems typically need to be kept above their freezing limits, around room temperature (15 C). Electronics needs to be kept typically above -40 C and batteries above -20 C. The next question becomes how to harvest this waste heat and direct it to the components that would need it for their survival. The proposed system utilizes a mechanically pumped, single phase fluid loop to pick up the waste heat from components attached to this loop's tubing and then directed to a thermal flask that has tubing attached to it. The thermal flask is cylindrically shaped and contains essentially all systems and components in the spacecraft within it, with the exception of the solar array, antennae, thrusters and various apertures of instruments, etc. to allow them an unobstructed view of space. Waste heat from the heat-dissipating components warms up the fluid and is carried to the flask surface and deposited on it via the fluid loop's flow. The entire flask is covered with Multi-Layered Insulation (MLI) to minimize the heat loss from the flask and allow it to remain warm. Hence the flask essentially creates a thermal environment within which the spacecraft components reside. The temperature of the components within the flask is then essentially the same as the temperature of the flask. This approach could be a very enabling feature for deep space missions. This paper describes the approach utilized for this thermal architecture, along with its mechanical and implementation aspects. Additionally it will compare and contrast this approach with the more conventional solutions utilized earlier.

A generalized predictive model for direct gain

DOE Office of Scientific and Technical Information (OSTI.GOV)

Givoni, B.

In the correlational model for direct gain developed by the Los Alamos National Laboratory, a list of constants applicable to different types of buildings or passive solar systems was specified separately for each type. In its original form, the model was applicable only to buildings similar in their heat capacity, type of glazing, or night insulation to the types specified by the model. While maintaining the general form of the predictive equations, the new model, the predictive model for direct gain (PMDG), replaces the constants with functions dependent upon the thermal properties of the building, or the components of themore » solar system, or both. By this transformation, the LANL model for direct gain becomes a generalized one. The new model predicts the performance of buildings heated by direct gain with any heat capacity, glazing, and night insulation as functions of their thermophysical properties and climatic conditions.« less

Investment appraisal of technology innovations on dairy farm electricity consumption.

PubMed

Upton, J; Murphy, M; De Boer, I J M; Groot Koerkamp, P W G; Berentsen, P B M; Shalloo, L

2015-02-01

The aim of this study was to conduct an investment appraisal for milk-cooling, water-heating, and milk-harvesting technologies on a range of farm sizes in 2 different electricity-pricing environments. This was achieved by using a model for electricity consumption on dairy farms. The model simulated the effect of 6 technology investment scenarios on the electricity consumption and electricity costs of the 3 largest electricity-consuming systems within the dairy farm (i.e., milk-cooling, water-heating, and milking machine systems). The technology investment scenarios were direct expansion milk-cooling, ice bank milk-cooling, milk precooling, solar water-heating, and variable speed drive vacuum pump-milking systems. A dairy farm profitability calculator was combined with the electricity consumption model to assess the effect of each investment scenario on the total discounted net income over a 10-yr period subsequent to the investment taking place. Included in the calculation were the initial investments, which were depreciated to zero over the 10-yr period. The return on additional investment for 5 investment scenarios compared with a base scenario was computed as the investment appraisal metric. The results of this study showed that the highest return on investment figures were realized by using a direct expansion milk-cooling system with precooling of milk to 15°C with water before milk entry to the storage tank, heating water with an electrical water-heating system, and using standard vacuum pump control on the milking system. Return on investment figures did not exceed the suggested hurdle rate of 10% for any of the ice bank scenarios, making the ice bank system reliant on a grant aid framework to reduce the initial capital investment and improve the return on investment. The solar water-heating and variable speed drive vacuum pump scenarios failed to produce positive return on investment figures on any of the 3 farm sizes considered on either the day and night tariff or the flat tariff, even when the technology costs were reduced by 40% in a sensitivity analysis of technology costs. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.