Capillary-Condenser-Pumped Heat-Transfer Loop

NASA Technical Reports Server (NTRS)

Silverstein, Calvin C.

1989-01-01

Heat being transferred supplies operating power. Capillary-condenser-pumped heat-transfer loop similar to heat pipe and to capillary-evaporator-pumped heat-transfer loop in that heat-transfer fluid pumped by evaporation and condensation of fluid at heat source and sink, respectively. Capillary condenser pump combined with capillary evaporator pump to form heat exchanger circulating heat-transfer fluids in both loops. Transport of heat more nearly isothermal. Thermal stress in loop reduced, and less external surface area needed in condenser section for rejection of heat to heat sink.

Evaporation of liquefied natural gas in conditions of compact storage containers heating

NASA Astrophysics Data System (ADS)

Telgozhayeva, D. S.

2014-08-01

Identical by its power, but located in different parts of the external surface of the tank, the heating sources are different intensity heat transfer modes is heating up, respectively, times of vapour pressure rise to critical values. Developed mathematical model and method of calculation can be used in the analysis of conditions of storage tanks for liquefied gases.

Flow and heat transfer enhancement in tube heat exchangers

NASA Astrophysics Data System (ADS)

Sayed Ahmed, Sayed Ahmed E.; Mesalhy, Osama M.; Abdelatief, Mohamed A.

2015-11-01

The performance of heat exchangers can be improved to perform a certain heat-transfer duty by heat transfer enhancement techniques. Enhancement techniques can be divided into two categories: passive and active. Active methods require external power, such as electric or acoustic field, mechanical devices, or surface vibration, whereas passive methods do not require external power but make use of a special surface geometry or fluid additive which cause heat transfer enhancement. The majority of commercially interesting enhancement techniques are passive ones. This paper presents a review of published works on the characteristics of heat transfer and flow in finned tube heat exchangers of the existing patterns. The review considers plain, louvered, slit, wavy, annular, longitudinal, and serrated fins. This review can be indicated by the status of the research in this area which is important. The comparison of finned tubes heat exchangers shows that those with slit, plain, and wavy finned tubes have the highest values of area goodness factor while the heat exchanger with annular fin shows the lowest. A better heat transfer coefficient ha is found for a heat exchanger with louvered finned and thus should be regarded as the most efficient one, at fixed pumping power per heat transfer area. This study points out that although numerous studies have been conducted on the characteristics of flow and heat transfer in round, elliptical, and flat tubes, studies on some types of streamlined-tubes shapes are limited, especially on wing-shaped tubes (Sayed Ahmed et al. in Heat Mass Transf 50: 1091-1102, 2014; in Heat Mass Transf 51: 1001-1016, 2015). It is recommended that further detailed studies via numerical simulations and/or experimental investigations should be carried out, in the future, to put further insight to these fin designs.

Prospects for energy recovery during hydrothermal and biological processing of waste biomass.

PubMed

Gerber Van Doren, Léda; Posmanik, Roy; Bicalho, Felipe A; Tester, Jefferson W; Sills, Deborah L

2017-02-01

Thermochemical and biological processes represent promising technologies for converting wet biomasses, such as animal manure, organic waste, or algae, to energy. To convert biomass to energy and bio-chemicals in an economical manner, internal energy recovery should be maximized to reduce the use of external heat and power. In this study, two conversion pathways that couple hydrothermal liquefaction with anaerobic digestion or catalytic hydrothermal gasification were compared. Each of these platforms is followed by two alternative processes for gas utilization: 1) combined heat and power; and 2) combustion in a boiler. Pinch analysis was applied to integrate thermal streams among unit processes and improve the overall system efficiency. A techno-economic analysis was conducted to compare the feasibility of the four modeled scenarios under different market conditions. Our results show that a systems approach designed to recover internal heat and power can reduce external energy demands and increase the overall process sustainability. Copyright © 2016 Elsevier Ltd. All rights reserved.

Thermoacoustically driven triboelectric nanogenerator: Combining thermoacoustics and nanoscience

NASA Astrophysics Data System (ADS)

Zhu, Shunmin; Yu, Aifang; Yu, Guoyao; Liu, Yudong; Zhai, Junyi; Dai, Wei; Luo, Ercang

2017-10-01

A thermoacoustic heat engine (TAHE) is a type of regenerative heat engine that converts external heat into mechanical power in the form of an acoustic wave with no moving mechanical components. One significant application of the TAHE is the generation of electricity by coupling an acoustic-to-electric conversion unit such as a linear motor or a piezoelectric ceramic assembly. However, present-day conversion technologies have considerable drawbacks, including structural complexity, high cost, and low reliability. The advent of triboelectric nanogenerators (TENGs) offers an alternative means to overcoming these shortcomings. In this paper, we propose a thermoacoustically driven TENG (TA-TENG) that continuously harvests external heat. A test rig involving a standing-wave TAHE and a contact-separation mode TENG was fabricated to demonstrate this concept. Currently, the TA-TENG produces a maximum output voltage of 10 V and a corresponding output power of 0.008 μW with a load of 400 MΩ, demonstrating the viability of this hybrid combination for electricity generation.

Cooled electrical terminal assembly and device incorporating same

DOEpatents

Beihoff, Bruce C.; Radosevich, Lawrence D.; Phillips, Mark G.; Kehl, Dennis L.; Kaishian, Steven C.; Kannenberg, Daniel G.

2006-08-22

A terminal structure provides interfacing with power electronics circuitry and external circuitry. The thermal support may receive one or more power electronic circuits. The support may aid in removing heat from the terminal structure and the circuits through fluid circulating through the support. The support may form a shield from both external EMI/RFI and from interference generated by operation of the power electronic circuits. Features may be provided to permit and enhance connection of the circuitry to external circuitry, such as improved terminal configurations. Modular units may be assembled that may be coupled to electronic circuitry via plug-in arrangements or through interface with a backplane or similar mounting and interconnecting structures.

Cooled electrical terminal assembly and device incorporating same

DOEpatents

Beihoff, Bruce C.; Radosevich, Lawrence D.; Phillips, Mark G.; Kehl, Dennis L.; Kaishian, Steven C.; Kannenberg, Daniel G.

2005-05-24

A terminal structure provides interfacing with power electronics circuitry and external circuitry. The thermal support may receive one or more power electronic circuits. The support may aid in removing heat from the terminal structure and the circuits through fluid circulating through the support. The support may form a shield from both external EMI/RFI and from interference generated by operation of the power electronic circuits. Features may be provided to permit and enhance connection of the circuitry to external circuitry, such as improved terminal configurations. Modular units may be assembled that may be coupled to electronic circuitry via plug-in arrangements or through interface with a backplane or similar mounting and interconnecting structures.

Performance of discrete heat engines and heat pumps in finite time

PubMed

Feldmann; Kosloff

2000-05-01

The performance in finite time of a discrete heat engine with internal friction is analyzed. The working fluid of the engine is composed of an ensemble of noninteracting two level systems. External work is applied by changing the external field and thus the internal energy levels. The friction induces a minimal cycle time. The power output of the engine is optimized with respect to time allocation between the contact time with the hot and cold baths as well as the adiabats. The engine's performance is also optimized with respect to the external fields. By reversing the cycle of operation a heat pump is constructed. The performance of the engine as a heat pump is also optimized. By varying the time allocation between the adiabats and the contact time with the reservoir a universal behavior can be identified. The optimal performance of the engine when the cold bath is approaching absolute zero is studied. It is found that the optimal cooling rate converges linearly to zero when the temperature approaches absolute zero.

Analysis of the energy efficiency of the implementation power electric generated modules in the CHS

NASA Astrophysics Data System (ADS)

Sukhikh, A. A.; Milyutin, V. A.; Lvova, A. M.

2017-11-01

Application on the Central heat source (CHS) local generation of electricity is primarily aimed at solving problems of own needs of electric energy that not only guarantees the independence of the work of the CHS from external electrical networks, but will prevent the stop of heat supply of consumers and defrosting heating networks in case of accidents in electrical networks caused by natural or anthropogenic factors. Open the prospects of electric power supply stand-alone objects, such commercial or industrial objects on the territory of a particular neighborhood.

Improved thermal isolation for superconducting magnet systems

NASA Technical Reports Server (NTRS)

Wiebe, E. R.

1974-01-01

Closed-cycle refrigerating system for superconductive magnet and maser is operated in vacuum environment. Each wire leading from external power source passes through cooling station which blocks heat conduction. In connection with these stations, switch with small incandescent light bulb, which generates heat, is used to stop superconduction.

Evaluation of externally heated pulsed MPD thruster cathodes

NASA Astrophysics Data System (ADS)

Myers, Roger M.; Domonkos, Matthew; Gallimore, Alec D.

1993-12-01

Recent interest in solar electric orbit transfer vehicles (SEOTV's) has prompted a reevaluation of pulsed magnetoplasmadynamic (MPD) thruster systems due to their ease of power scaling and reduced test facility requirements. In this work the use of externally heated cathodes was examined in order to extend the lifetime of these thrusters to the 1000 to 3000 hours required for SEOTV missions. A pulsed MPD thruster test facility was assembled, including a pulse-forming network (PFN), ignitor supply and propellant feed system. Results of cold cathode tests used to validate the facility, PFN, and propellant feed system design are presented, as well as a preliminary evaluation of externally heated impregnated tungsten cathodes. The cold cathode thruster was operated on both argon and nitrogen propellants at peak discharge power levels up to 300 kW. The results confirmed proper operation of the pulsed thruster test facility, and indicated that large amounts of gas were evolved from the BaO-CaO-Al2O3 cathodes during activation. Comparison of the expected space charge limited current with the measured vacuum current when using the heated cathode indicate that either that a large temperature difference existed between the heater and the cathode or that the surface work function was higher than expected.

Evaluation of externally heated pulsed MPD thruster cathodes

NASA Technical Reports Server (NTRS)

Myers, Roger M.; Domonkos, Matthew; Gallimore, Alec D.

1993-01-01

Recent interest in solar electric orbit transfer vehicles (SEOTV's) has prompted a reevaluation of pulsed magnetoplasmadynamic (MPD) thruster systems due to their ease of power scaling and reduced test facility requirements. In this work the use of externally heated cathodes was examined in order to extend the lifetime of these thrusters to the 1000 to 3000 hours required for SEOTV missions. A pulsed MPD thruster test facility was assembled, including a pulse-forming network (PFN), ignitor supply and propellant feed system. Results of cold cathode tests used to validate the facility, PFN, and propellant feed system design are presented, as well as a preliminary evaluation of externally heated impregnated tungsten cathodes. The cold cathode thruster was operated on both argon and nitrogen propellants at peak discharge power levels up to 300 kW. The results confirmed proper operation of the pulsed thruster test facility, and indicated that large amounts of gas were evolved from the BaO-CaO-Al2O3 cathodes during activation. Comparison of the expected space charge limited current with the measured vacuum current when using the heated cathode indicate that either that a large temperature difference existed between the heater and the cathode or that the surface work function was higher than expected.

Numerical investigations of MRI RF field induced heating for external fixation devices

PubMed Central

2013-01-01

Background The magnetic resonance imaging (MRI) radio frequency (RF) field induced heating on external fixation devices can be very high in the vicinity of device screws. Such induced RF heating is related to device constructs, device placements, as well as the device insertion depth into human subjects. In this study, computational modeling is performed to determine factors associated with such induced heating. Methods Numerical modeling, based on the finite-difference time-domain (FDTD) method, is used to evaluate the temperature rises near external device screw tips inside the ASTM phantom for both 1.5-T and 3-T MRI systems. The modeling approach consists of 1) the development of RF coils for 1.5-T and 3-T, 2) the electromagnetic simulations of energy deposition near the screw tips of external fixation devices, and 3) the thermal simulations of temperature rises near the tips of these devices. Results It is found that changing insertion depth and screw spacing could largely affect the heating of these devices. In 1.5-T MRI system, smaller insertion depth and larger pin spacing will lead to higher temperature rise. However, for 3-T MRI system, the relation is not very clear when insertion depth is larger than 5 cm or when pin spacing became larger than 20 cm. The effect of connection bar material on device heating is also studied and the heating mechanism of the device is analysed. Conclusions Numerical simulation is used to study RF heating for external fixation devices in both 1.5-T and 3-T MRI coils. Typically, shallower insertion depth and larger pin spacing with conductive bar lead to higher RF heating. The heating mechanism is explained using induced current along the device and power decay inside ASTM phantom. PMID:23394173

Laser-powered thermoelectric generators operating at cryogenic temperatures

NASA Astrophysics Data System (ADS)

Harutyunyan, S. R.; Vardanyan, V. H.; Kuzanyan, A. S.; Nikoghosyan, V. R.; Kunii, S.; Winzer, K.; Wood, K. S.; Gulian, A. M.

2005-11-01

A thermoelectric generator, operating in a cryostat at liquid helium temperatures, is described. Energy to the generator is supplied via an external laser beam. For this prototype device the associated heat load at permanent operation is comparable with the heat load associated with power delivery via metallic wires. Estimates indicate that still better performance can be enabled with existing thermoelectric materials, thereby far exceeding efficiency of traditional cryostat wiring. We used a prototype generator to produce electric power for measuring critical currents in Nb3Sn-films at 4K.

Stirling engine external heat system design with heat pipe heater

NASA Technical Reports Server (NTRS)

Godett, Ted M.; Ziph, Benjamin

1986-01-01

This final report presents the conceptual design of a liquid fueled external heating system (EHS) and the preliminary design of a heat pipe heater for the STM-4120 Stirling cycle engine, to meet the Air Force mobile electric power (MEP) requirement for units in the range of 20 to 60 kW. The EHS design had the following constraints: (1) Packaging requirements limited the overall system dimensions to about 330 mm x 250 mm x 100 mm; (2) Heat flux to the sodium heat pipe evaporator was limited to an average of 100 kW/m and a maximum of 550 kW/m based on previous experience; and (3) The heat pipe operating temperature was specified to be 800 C based on heat input requirements of the STM4-120. An analysis code was developed to optimize the EHS performance parameters and an analytical development of the sodium heat pipe heater was performed; both are presented and discussed. In addition, construction techniques were evaluated and scale model heat pipe testing performed.

Modular power converter having fluid cooled support

DOEpatents

Beihoff, Bruce C.; Radosevich, Lawrence D.; Meyer, Andreas A.; Gollhardt, Neil; Kannenberg, Daniel G.

2005-09-06

A support may receive one or more power electronic circuits. The support may aid in removing heat from the circuits through fluid circulating through the support. The support, in conjunction with other packaging features may form a shield from both external EMI/RFI and from interference generated by operation of the power electronic circuits. Features may be provided to permit and enhance connection of the circuitry to external circuitry, such as improved terminal configurations. Modular units may be assembled that may be coupled to electronic circuitry via plug-in arrangements or through interface with a backplane or similar mounting and interconnecting structures.

Modular power converter having fluid cooled support

DOEpatents

Beihoff, Bruce C.; Radosevich, Lawrence D.; Meyer, Andreas A.; Gollhardt, Neil; Kannenberg, Daniel G.

2005-12-06

A support may receive one or more power electronic circuits. The support may aid in removing heat from the circuits through fluid circulating through the support. The support, in conjunction with other packaging features may form a shield from both external EMI/RFI and from interference generated by operation of the power electronic circuits. Features may be provided to permit and enhance connection of the circuitry to external circuitry, such as improved terminal configurations. Modular units may be assembled that may be coupled to electronic circuitry via plug-in arrangements or through interface with a backplane or similar mounting and interconnecting structures.

Compact fluid cooled power converter supporting multiple circuit boards

DOEpatents

Radosevich, Lawrence D.; Meyer, Andreas A.; Beihoff, Bruce C.; Kannenberg, Daniel G.

2005-03-08

A support may receive one or more power electronic circuits. The support may aid in removing heat from the circuits through fluid circulating through the support. The support, in conjunction with other packaging features may form a shield from both external EMI/RFI and from interference generated by operation of the power electronic circuits. Features may be provided to permit and enhance connection of the circuitry to external circuitry, such as improved terminal configurations. Modular units may be assembled that may be coupled to electronic circuitry via plug-in arrangements or through interface with a backplane or similar mounting and interconnecting structures.

Laser engines operating by resonance absorption. [thermodynamic feasibility study

NASA Technical Reports Server (NTRS)

Garbuny, M.; Pechersky, M. J.

1976-01-01

Basic tutorial article on the thermodynamic feasibility of laser engines at the present state of the art. Three main options are considered: (1) laser power applied externally to a heat reservoir (boiler approach); (2) internal heating of working fluid by resonance absorption; and (3) direct conversion of selective excitation into work. Only (2) is considered practically feasible at present. Basic concepts and variants, efficiency relations, upper temperature limits of laser engines, selection of absorbing gases, engine walls, bleaching, thermodynamic cycles of optimized laser engines, laser-powered turbines, laser heat pumps are discussed. Photon engines and laser dissociation engines are also considered.

Intracorporeal Heat Distribution from Fully Implantable Energy Sources for Mechanical Circulatory Support: A Computational Proof-of-Concept Study

PubMed Central

Biasetti, Jacopo; Pustavoitau, Aliaksei; Spazzini, Pier Giorgio

2017-01-01

Mechanical circulatory support devices, such as total artificial hearts and left ventricular assist devices, rely on external energy sources for their continuous operation. Clinically approved power supplies rely on percutaneous cables connecting an external energy source to the implanted device with the associated risk of infections. One alternative, investigated in the 70s and 80s, employs a fully implanted nuclear power source. The heat generated by the nuclear decay can be converted into electricity to power circulatory support devices. Due to the low conversion efficiencies, substantial levels of waste heat are generated and must be dissipated to avoid tissue damage, heat stroke, and death. The present work computationally evaluates the ability of the blood flow in the descending aorta to remove the locally generated waste heat for subsequent full-body distribution and dissipation, with the specific aim of investigating methods for containment of local peak temperatures within physiologically acceptable limits. To this aim, coupled fluid–solid heat transfer computational models of the blood flow in the human aorta and different heat exchanger architectures are developed. Particle tracking is used to evaluate temperature histories of cells passing through the heat exchanger region. The use of the blood flow in the descending aorta as a heat sink proves to be a viable approach for the removal of waste heat loads. With the basic heat exchanger design, blood thermal boundary layer temperatures exceed 50°C, possibly damaging blood cells and proteins. Improved designs of the heat exchanger, with the addition of fins and heat guides, allow for drastically lower blood temperatures, possibly leading to a more biocompatible implant. The ability to maintain blood temperatures at biologically compatible levels will ultimately allow for the body-wise distribution, and subsequent dissipation, of heat loads with minimum effects on the human physiology. PMID:29094038

Intracorporeal Heat Distribution from Fully Implantable Energy Sources for Mechanical Circulatory Support: A Computational Proof-of-Concept Study.

PubMed

Biasetti, Jacopo; Pustavoitau, Aliaksei; Spazzini, Pier Giorgio

2017-01-01

Mechanical circulatory support devices, such as total artificial hearts and left ventricular assist devices, rely on external energy sources for their continuous operation. Clinically approved power supplies rely on percutaneous cables connecting an external energy source to the implanted device with the associated risk of infections. One alternative, investigated in the 70s and 80s, employs a fully implanted nuclear power source. The heat generated by the nuclear decay can be converted into electricity to power circulatory support devices. Due to the low conversion efficiencies, substantial levels of waste heat are generated and must be dissipated to avoid tissue damage, heat stroke, and death. The present work computationally evaluates the ability of the blood flow in the descending aorta to remove the locally generated waste heat for subsequent full-body distribution and dissipation, with the specific aim of investigating methods for containment of local peak temperatures within physiologically acceptable limits. To this aim, coupled fluid-solid heat transfer computational models of the blood flow in the human aorta and different heat exchanger architectures are developed. Particle tracking is used to evaluate temperature histories of cells passing through the heat exchanger region. The use of the blood flow in the descending aorta as a heat sink proves to be a viable approach for the removal of waste heat loads. With the basic heat exchanger design, blood thermal boundary layer temperatures exceed 50°C, possibly damaging blood cells and proteins. Improved designs of the heat exchanger, with the addition of fins and heat guides, allow for drastically lower blood temperatures, possibly leading to a more biocompatible implant. The ability to maintain blood temperatures at biologically compatible levels will ultimately allow for the body-wise distribution, and subsequent dissipation, of heat loads with minimum effects on the human physiology.

Lithium-ion battery structure that self-heats at low temperatures

NASA Astrophysics Data System (ADS)

Wang, Chao-Yang; Zhang, Guangsheng; Ge, Shanhai; Xu, Terrence; Ji, Yan; Yang, Xiao-Guang; Leng, Yongjun

2016-01-01

Lithium-ion batteries suffer severe power loss at temperatures below zero degrees Celsius, limiting their use in applications such as electric cars in cold climates and high-altitude drones. The practical consequences of such power loss are the need for larger, more expensive battery packs to perform engine cold cranking, slow charging in cold weather, restricted regenerative braking, and reduction of vehicle cruise range by as much as 40 per cent. Previous attempts to improve the low-temperature performance of lithium-ion batteries have focused on developing additives to improve the low-temperature behaviour of electrolytes, and on externally heating and insulating the cells. Here we report a lithium-ion battery structure, the ‘all-climate battery’ cell, that heats itself up from below zero degrees Celsius without requiring external heating devices or electrolyte additives. The self-heating mechanism creates an electrochemical interface that is favourable for high discharge/charge power. We show that the internal warm-up of such a cell to zero degrees Celsius occurs within 20 seconds at minus 20 degrees Celsius and within 30 seconds at minus 30 degrees Celsius, consuming only 3.8 per cent and 5.5 per cent of cell capacity, respectively. The self-heated all-climate battery cell yields a discharge/regeneration power of 1,061/1,425 watts per kilogram at a 50 per cent state of charge and at minus 30 degrees Celsius, delivering 6.4-12.3 times the power of state-of-the-art lithium-ion cells. We expect the all-climate battery to enable engine stop-start technology capable of saving 5-10 per cent of the fuel for 80 million new vehicles manufactured every year. Given that only a small fraction of the battery energy is used for self-heating, we envisage that the all-climate battery cell may also prove useful for plug-in electric vehicles, robotics and space exploration applications.

Lithium-ion battery structure that self-heats at low temperatures.

PubMed

Wang, Chao-Yang; Zhang, Guangsheng; Ge, Shanhai; Xu, Terrence; Ji, Yan; Yang, Xiao-Guang; Leng, Yongjun

2016-01-28

Lithium-ion batteries suffer severe power loss at temperatures below zero degrees Celsius, limiting their use in applications such as electric cars in cold climates and high-altitude drones. The practical consequences of such power loss are the need for larger, more expensive battery packs to perform engine cold cranking, slow charging in cold weather, restricted regenerative braking, and reduction of vehicle cruise range by as much as 40 per cent. Previous attempts to improve the low-temperature performance of lithium-ion batteries have focused on developing additives to improve the low-temperature behaviour of electrolytes, and on externally heating and insulating the cells. Here we report a lithium-ion battery structure, the 'all-climate battery' cell, that heats itself up from below zero degrees Celsius without requiring external heating devices or electrolyte additives. The self-heating mechanism creates an electrochemical interface that is favourable for high discharge/charge power. We show that the internal warm-up of such a cell to zero degrees Celsius occurs within 20 seconds at minus 20 degrees Celsius and within 30 seconds at minus 30 degrees Celsius, consuming only 3.8 per cent and 5.5 per cent of cell capacity, respectively. The self-heated all-climate battery cell yields a discharge/regeneration power of 1,061/1,425 watts per kilogram at a 50 per cent state of charge and at minus 30 degrees Celsius, delivering 6.4-12.3 times the power of state-of-the-art lithium-ion cells. We expect the all-climate battery to enable engine stop-start technology capable of saving 5-10 per cent of the fuel for 80 million new vehicles manufactured every year. Given that only a small fraction of the battery energy is used for self-heating, we envisage that the all-climate battery cell may also prove useful for plug-in electric vehicles, robotics and space exploration applications.

Research: Testing of a Novel Portable Body Temperature Conditioner Using a Thermal Manikin.

PubMed

Heller, Daniel; Heller, Alex; Moujaes, Samir; Williams, Shelley J; Hoffmann, Ryan; Sarkisian, Paul; Khalili, Kaveh; Rockenfeller, Uwe; Browder, Timothy D; Kuhls, Deborah A; Fildes, John J

2016-01-01

A battery-operated active cooling/heating device was developed to maintain thermoregulation of trauma victims in austere environments while awaiting evacuation to a hospital for further treatment. The use of a thermal manikin was adopted for this study in order to simulate load testing and evaluate the performance of this novel portable active cooling/heating device for both continuous (external power source) and battery power. The performance of the portable body temperature conditioner (PBTC) was evaluated through cooling/heating fraction tests to analyze the heat transfer between a thermal manikin and circulating water blanket to show consistent performance while operating under battery power. For the cooling/heating fraction tests, the ambient temperature was set to 15°C ± 1°C (heating) and 30°C ± 1°C (cooling). The PBTC water temperature was set to 37°C for the heating mode tests and 15°C for the cooling mode tests. The results showed consistent performance of the PBTC in terms of cooling/heating capacity while operating under both continuous and battery power. The PBTC functioned as intended and shows promise as a portable warming/cooling device for operation in the field.

Power converter having improved EMI shielding

DOEpatents

Beihoff, Bruce C.; Kehl, Dennis L.; Gettelfinger, Lee A.; Kaishian, Steven C.; Phillips, Mark G.; Radosevich, Lawrence D.

2006-06-13

EMI shielding is provided for power electronics circuits and the like via a direct-mount reference plane support and shielding structure. The thermal support may receive one or more power electronic circuits. The support may aid in removing heat from the circuits through fluid circulating through the support. The support forms a shield from both external EMI/RFI and from interference generated by operation of the power electronic circuits. Features may be provided to permit and enhance connection of the circuitry to external circuitry, such as improved terminal configurations. Modular units may be assembled that may be coupled to electronic circuitry via plug-in arrangements or through interface with a backplane or similar mounting and interconnecting structures.

Power converter connection configuration

DOEpatents

Beihoff, Bruce C.; Kehl, Dennis L.; Gettelfinger, Lee A.; Kaishian, Steven C.; Phillips, Mark G.; Radosevich, Lawrence D.

2008-11-11

EMI shielding is provided for power electronics circuits and the like via a direct-mount reference plane support and shielding structure. The thermal support may receive one or more power electronic circuits. The support may aid in removing heat from the circuits through fluid circulating through the support. The support forms a shield from both external EMI/RFI and from interference generated by operation of the power electronic circuits. Features may be provided to permit and enhance connection of the circuitry to external circuitry, such as improved terminal configurations. Modular units may be assembled that may be coupled to electronic circuitry via plug-in arrangements or through interface with a backplane or similar mounting and interconnecting structures.

Thermally matched fluid cooled power converter

DOEpatents

Radosevich, Lawrence D.; Kannenberg, Daniel G.; Kaishian, Steven C.; Beihoff, Bruce C.

2005-06-21

A thermal support may receive one or more power electronic circuits. The support may aid in removing heat from the circuits through fluid circulating through the support. Power electronic circuits are thermally matched, such as between component layers and between the circuits and the support. The support may form a shield from both external EMI/RFI and from interference generated by operation of the power electronic circuits. Features may be provided to permit and enhance connection of the circuitry to external circuitry, such as improved terminal configurations. Modular units may be assembled that may be coupled to electronic circuitry via plug-in arrangements or through interface with a backplane or similar mounting and interconnecting structures.

Optimal design of implants for magnetically mediated hyperthermia: A wireless power transfer approach

NASA Astrophysics Data System (ADS)

Lang, Hans-Dieter; Sarris, Costas D.

2017-09-01

In magnetically mediated hyperthermia (MMH), an externally applied alternating magnetic field interacts with a mediator (such as a magnetic nanoparticle or an implant) inside the body to heat up the tissue in its proximity. Producing heat via induced currents in this manner is strikingly similar to wireless power transfer (WPT) for implants, where power is transferred from a transmitter outside of the body to an implanted receiver, in most cases via magnetic fields as well. Leveraging this analogy, a systematic method to design MMH implants for optimal heating efficiency is introduced, akin to the design of WPT systems for optimal power transfer efficiency. This paper provides analytical formulas for the achievable heating efficiency bounds as well as the optimal operating frequency and the implant material. Multiphysics simulations validate the approach and further demonstrate that optimization with respect to maximum heating efficiency is accompanied by minimizing heat delivery to healthy tissue. This is a property that is highly desirable when considering MMH as a key component or complementary method of cancer treatment and other applications.

A numerical investigation of a thermodielectric power generation system

NASA Astrophysics Data System (ADS)

Sklar, Akiva A.

The performance of a novel micro-thermodielectric power generation system was investigated in order to determine if thermodielectric power generation can be practically employed and if its performance can compete with current portable power generation technologies. Thermodielectric power generation is a direct energy conversion technology that converts heat directly into high voltage direct current. It requires dielectric (i.e., capacitive) materials whose charge storing capabilities are a function of temperature. This property can be exploited by heating these materials after they are charged; as their temperature increases, their charge storage capability decreases, forcing them to eject a portion of their surface charge. This ejected charge can then be supplied to an appropriate electronic storage device. There are several advantages associated with thermodielectric energy conversion; first, it requires heat addition at relatively low conventional power generation temperatures, i.e., less than 600 °K, and second, devices that utilize it have the potential for excellent power density and device reliability. The predominant disadvantage of using this power generation technique is that the device must operate in an unsteady manner; this can lead to substantial heat transfer losses that limit the device's thermal efficiency. The studied power generation system was designed so that the power generating components of the system (i.e., the thermodielectric materials) are integrated within a micro-scale heat exchange apparatus designed specifically to provide the thermodielectric materials with the unsteady heating and cooling necessary for efficient power generation. This apparatus is designed to utilize a liquid as a working fluid in order to maximize its heat transfer capabilities, minimize the size of the heat exchanger, and maximize the power density of the power generation system. The thermodielectric materials are operated through a power generation cycle that consists of four processes; the first process is a charging process, during which an electric field is applied to a thermodielectric material, causing it to acquire electrical charge on its surface (this process is analogous to the isentropic compression process of a Brayton cycle). The second process is a heating process in which the temperature of the dielectric material is increased via heat transfer from an external source. During this process, the thermodielectric material is forced to eject a portion of its surface charge because its charge storing capability decreases as the temperature increases; the ejected charge is intended for capture by external circuitry connected to the thermodielectric material, where it can be routed to an electrochemical storage device or an electromechanical device requiring high voltage direct current. The third process is a discharging process, during which the applied electric field is reduced to its initial strength (analogous to the isentropic expansion process of a Brayton cycle). The final process is a cooling process in which the temperature of the dielectric material is decreased via heat transfer from an external source, returning it to its initial temperature. Previously, predicting the performance of a thermodielectric power generator was hindered by a poor understanding of the material's thermodynamic properties and the effect unsteady heat transfer losses have on system performance. In order to improve predictive capabilities in this study, a thermodielectric equation of state was developed that relates the strength of the applied electric field, the amount of surface charge stored by the thermodielectric material, and its temperature. This state equation was then used to derive expressions for the material's thermodynamic states (internal energy, entropy), which were subsequently used to determine the optimum material properties for power generation. Next, a numerical simulation code was developed to determine the heat transfer capabilities of a micro-scale parallel plate heat recuperator (MPPHR), a device designed specifically to (a) provide the unsteady heating and cooling necessary for thermodielectric power generation and (b) minimize the unsteady heat transfer losses of the system. The simulation code was used to find the optimum heat transfer and heat recuperation regimes of the MPPHR. The previously derived thermodynamic equations that describe the behavior of the thermodielectric materials were then incorporated into the model for the walls of the parallel plate channel in the numerical simulation code, creating a tool capable of determining the thermodynamic performance of an MTDPG, in terms of the thermal efficiency, percent Carnot efficiency, and energy/power density. A detailed parameterization of the MTDPG with the simulation code yielded the critical non-dimensional numbers that determine the relationship between the heat exchange/recuperation abilities of the flow and the power generation capabilities of the thermodielectric materials. These relationships were subsequently used to optimize the performance of an MTDPG with an operating temperature range of 300--500 °K. The optimization predicted that the MTDPG could provide a thermal efficiency of 29.7 percent with the potential to reach 34 percent. These thermal efficiencies correspond to 74.2 and 85 percent of the Carnot efficiency, respectively. The power density of this MTDPG depends on the operating frequency and can exceed 1,000,000 W/m3.

Coordinated Research Program in Pulsed Power Physics.

DTIC Science & Technology

1984-12-20

heated array of Inductive energy storage is attractive in pulsed power 375-/am-diameter thoriated tungsten filaments. At a flia- applications because of...control system electrostatical- ly. It is positioned 0.6 cm above the control grid. The grids and cathode are connected to external power supplies through...energy storage density becomes even larger (by a factor of - 10). One should note that these comparisons do not account for power supplies , cooling

Electrical power converter method and system employing multiple output converters

DOEpatents

Beihoff, Bruce C [Wauwatosa, WI; Radosevich, Lawrence D [Muskego, WI; Meyer, Andreas A [Richmond Heights, OH; Gollhardt, Neil [Fox Point, WI; Kannenberg, Daniel G [Waukesha, WI

2007-05-01

A support may receive one or more power electronic circuits. The support may aid in removing heat from the circuits through fluid circulating through the support. The support, in conjunction with other packaging features may form a shield from both external EMI/RFI and from interference generated by operation of the power electronic circuits. Features may be provided to permit and enhance connection of the circuitry to external circuitry, such as improved terminal configurations. Modular units may be assembled that may be coupled to electronic circuitry via plug-in arrangements or through interface with a backplane or similar mounting and interconnecting structures.

Electrical power converter method and system employing multiple-output converters

DOEpatents

Beihoff, Bruce C.; Radosevich, Lawrence D.; Meyer, Andreas A.; Gollhardt, Neil; Kannenberg, Daniel G.

2006-03-21

A support may receive one or more power electronic circuits. The support may aid in removing heat from the circuits through fluid circulating through the support. The support, in conjunction with other packaging features may form a shield from both external EMI/RFI and from interference generated by operation of the power electronic circuits. Features may be provided to permit and enhance connection of the circuitry to external circuitry, such as improved terminal configurations. Modular units may be assembled that may be coupled to electronic circuitry via plug-in arrangements or through interface with a backplane or similar mounting and interconnecting structures.

Externally Induced Evaporation of Young Stellar Disks in Orion

NASA Technical Reports Server (NTRS)

Johnstone, D.; Hollenbach, D.; Shu, F.

1996-01-01

In this paper we propose a model for the evaporation of disks around young low-mass stars by external sources of high energy photons. Two evaporation techniques are possible. Lyman continuum radiation can ionize hydrogen at the disk surface powering a steady thermal ionized disk-wind, or FUV radiation can heat the disk through photo-electric grain processes powering a slower thermal neutral disk-wind. Applying these two models to the evaporating objects in the Trapezium produces a satisfactory solution to both the mass-loss rate and size of the ionized envelopes.

Energy Conversion Alternatives Study (ECAS), Westinghouse phase 1. Volume 9: Closed-cycle MHD. [energy conversion efficiency of electric power plants using magnetohydrodynamics

NASA Technical Reports Server (NTRS)

Tsu, T. C.

1976-01-01

A closed-cycle MHD system for an electric power plant was studied. It consists of 3 interlocking loops, an external heating loop, a closed-cycle cesium seeded argon nonequilibrium ionization MHD loop, and a steam bottomer. A MHD duct maximum temperature of 2366 K (3800 F), a pressure of 0.939 MPa (9.27 atm) and a Mach number of 0.9 are found to give a topping cycle efficiency of 59.3%; however when combined with an integrated gasifier and optimistic steam bottomer the coal to bus bar efficiency drops to 45.5%. A 1978 K (3100 F) cycle has an efficiency of 55.1% and a power plant efficiency of 42.2%. The high cost of the external heating loop components results in a cost of electricity of 21.41 mills/MJ (77.07 mills/kWh) for the high temperature system and 19.0 mills/MJ (68.5 mills/kWh) for the lower temperature system. It is, therefore, thought that this cycle may be more applicable to internally heated systems such as some futuristic high temperature gas cooled reactor.

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.

Optimize out-of-core thermionic energy conversion for nuclear electric propulsion

NASA Technical Reports Server (NTRS)

Morris, J. F.

1977-01-01

Current designs for out of core thermionic energy conversion (TEC) to power nuclear electric propulsion (NEP) were evaluated. Approaches to improve out of core TEC are emphasized and probabilities for success are indicated. TEC gains are available with higher emitter temperatures and greater power densities. Good potentialities for accommodating external high temperature, high power density TEC with heat pipe cooled reactors exist.

Unifying quantum heat transfer in a nonequilibrium spin-boson model with full counting statistics

NASA Astrophysics Data System (ADS)

Wang, Chen; Ren, Jie; Cao, Jianshu

2017-02-01

To study the full counting statistics of quantum heat transfer in a driven nonequilibrium spin-boson model, we develop a generalized nonequilibrium polaron-transformed Redfield equation with an auxiliary counting field. This enables us to study the impact of qubit-bath coupling ranging from weak to strong regimes. Without external modulations, we observe maximal values of both steady-state heat flux and noise power in moderate coupling regimes, below which we find that these two transport quantities are enhanced by the finite-qubit-energy bias. With external modulations, the geometric-phase-induced heat flux shows a monotonic decrease upon increasing the qubit-bath coupling at zero qubit energy bias (without bias). While under the finite-qubit-energy bias (with bias), the geometric-phase-induced heat flux exhibits an interesting reversal behavior in the strong coupling regime. Our results unify the seemingly contradictory results in weak and strong qubit-bath coupling regimes and provide detailed dissections for the quantum fluctuation of nonequilibrium heat transfer.

An investigation of the heat induced during ultrasonic post removal.

PubMed

Ettrich, Christopher A; Labossière, Paul E; Pitts, David L; Johnson, James D

2007-10-01

The purpose of this study was to investigate the potential for temperature increase along the external root surface during ultrasonic post removal in a simulated clinical environment. Thirty-seven extracted teeth were decoronated, instrumented, and then obturated with gutta-percha and sealer. Post spaces were prepared, followed by cementation of stainless steel posts. A simulated clinical environment was created by using a polymethylmethacrylate sheet with holes custom fitted for the extracted teeth and then suspended over a heated water bath. Two thermocouples were attached at 6 and 12 mm from the top of the post along the external root surface. Teeth were divided into 3 test groups, no coolant, air-cooled, and water-cooled. Temperature changes were recorded by using a Vishay 5000 Strain Smart system. Results demonstrated that a significant difference existed in the average heat rates between the upper and lower thermocouples for no coolant and water-cooled groups at the medium setting and the air-cooled group at the high setting. The average heat rates were significantly different between the 2 thermocouples for all 3 groups when comparing the 2 ultrasonic power settings. Results indicated that the average heat rate was less for the water-cooled group when using a medium power setting.

Quantum heat engines and refrigerators: continuous devices.

PubMed

Kosloff, Ronnie; Levy, Amikam

2014-01-01

Quantum thermodynamics supplies a consistent description of quantum heat engines and refrigerators up to a single few-level system coupled to the environment. Once the environment is split into three (a hot, cold, and work reservoir), a heat engine can operate. The device converts the positive gain into power, with the gain obtained from population inversion between the components of the device. Reversing the operation transforms the device into a quantum refrigerator. The quantum tricycle, a device connected by three external leads to three heat reservoirs, is used as a template for engines and refrigerators. The equation of motion for the heat currents and power can be derived from first principles. Only a global description of the coupling of the device to the reservoirs is consistent with the first and second laws of thermodynamics. Optimization of the devices leads to a balanced set of parameters in which the couplings to the three reservoirs are of the same order and the external driving field is in resonance. When analyzing refrigerators, one needs to devote special attention to a dynamical version of the third law of thermodynamics. Bounds on the rate of cooling when Tc→0 are obtained by optimizing the cooling current. All refrigerators as Tc→0 show universal behavior. The dynamical version of the third law imposes restrictions on the scaling as Tc→0 of the relaxation rate γc and heat capacity cV of the cold bath.

Vehicle drive module having improved cooling configuration

DOEpatents

Radosevich, Lawrence D.; Meyer, Andreas A.; Kannenberg, Daniel G.; Kaishian, Steven C.; Beihoff, Bruce C.

2007-02-13

An electric vehicle drive includes a thermal support may receive one or more power electronic circuits. The support may aid in removing heat from the circuits through fluid circulating through the support. Power electronic circuits are thermally matched, such as between component layers and between the circuits and the support. The support may form a shield from both external EMI/RFI and from interference generated by operation of the power electronic circuits. Features may be provided to permit and enhance connection of the circuitry to external circuitry, such as improved terminal configurations. Modular units may be assembled that may be coupled to electronic circuitry via plug-in arrangements or through interface with a backplane or similar mounting and interconnecting structures.

Power converter having improved fluid cooling

DOEpatents

Meyer, Andreas A.; Radosevich, Lawrence D.; Beihoff, Bruce C.; Kehl, Dennis L.; Kannenberg, Daniel G.

2007-03-06

A thermal support may receive one or more power electronic circuits. The support may aid in removing heat from the circuits through fluid circulating through the support, which may be controlled in a closed-loop manner. Interfacing between circuits, circuit mounting structure, and the support provide for greatly enhanced cooling. The support may form a shield from both external EMI/RFI and from interference generated by operation of the power electronic circuits. Features may be provided to permit and enhance connection of the circuitry to external circuitry, such as improved terminal configurations. Modular units may be assembled that may be coupled to electronic circuitry via plug-in arrangements or through interface with a backplane or similar mounting and interconnecting structures.

Radii and Orbits of Hot Jupiters

NASA Astrophysics Data System (ADS)

Wu, Yanqin

2011-09-01

Hot jupiters suffer extreme external (stellar) and internal (tidal, Ohmic and wind-power) heating. These lead to peculiar thermal evolution, which is potentially self-destrutive. For instance, the amount of energy deposited during tidal dissipation far exceeds the planets' binding energy. If this energy is mostly deposited in shallow layers, it does little damage to the planet. However, the presence of stellar insolation changes the picture, and Ohmic/wind-power heating further modifies the subsequent evolution of these jupiters. A diversity of planetary sizes results. We tie these thermodynamical processes together with the migration history of hot jupiters to explain the orbital distribution and physical radii of hot jupiters. Moreover, we constrain the location of tidal heating inside the planet.

Advanced thermionic converter developments with microwave external pumping

NASA Technical Reports Server (NTRS)

Chiu, H. S.; Shaw, D. T.; Manikopulos, C. N.; Lee, C. H.

1977-01-01

This work reports ion generation in a cesium thermionic converter as part of advanced-model thermionic converter development research. A microwave with frequency in the range between 1-2 GHz is used to externally pump a thermionic converter as part of our effort in the verification of Lam's theory. It is found that the motive peak as predicted in the theory disappears whenever microwave power is used to excite the cesium plasma of the converter. The electron temperature is effectively heated by the microwave and the experimental data agrees with theory in the low-power output region.

Reliability and Heat Transfer Performance of a Miniature High-Temperature Thermosyphon-Based Thermal Valve

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

Alleman, Jeffrey L; Olsen, Michele L; Glatzmaier, Gregory C

Latent heat thermal energy storage systems have the advantages of near isothermal heat release and high energy density compared to sensible heat, generally resulting in higher power block efficiencies. Until now, there has been no highly effective and reliable method to passively extract that stored latent energy. Most modern attempts rely on external power supplied to a pump to move viscous heat transfer fluids from the phase change material (PCM) to the power block. In this work, the problem of latent heat dispatchability has been addressed with a redesigned thermosyphon geometry that can act as a 'thermal valve' capable ofmore » passively and efficiently controlling the release of heat from a thermal reservoir. A bench-scale prototype with a stainless steel casing and sodium working fluid was designed and tested to be reliable for more than fifty 'on/off' cycles at an operating temperature of 600 degrees C. The measured thermal resistances in the 'on' and 'off' states were 0.0395 K/W and 11.0 K/W respectively. This device demonstrated efficient, fast, reliable, and passive heat extraction from a PCM and may have application to other fields and industries using thermal processing.« less

Suction-recirculation device for stabilizing particle flows within a solar powered solid particle receiver

DOEpatents

Kolb, Gregory J [Albuquerque, NM

2012-02-07

A suction-recirculation device for stabilizing the flow of a curtain of blackened heat absorption particles falling inside of a solar receiver with an open aperture. The curtain of particles absorbs the concentrated heat from a solar mirror array reflected up to the receiver on a solar power tower. External winds entering the receiver at an oblique angle can destabilize the particle curtain and eject particles. A fan and ductwork is located behind the back wall of the receiver and sucks air out through an array of small holes in the back wall. Any entrained particles are separated out by a conventional cyclone device. Then, the air is recirculated back to the top of the receiver by injecting the recycled air through an array of small holes in the receiver's ceiling and upper aperture front wall. Since internal air is recirculated, heat losses are minimized and high receiver efficiency is maintained. Suction-recirculation velocities in the range of 1-5 m/s are sufficient to stabilize the particle curtain against external wind speeds in excess of 10 m/s.

Optimum size of nanorods for heating application

NASA Astrophysics Data System (ADS)

Seshadri, G.; Thaokar, Rochish; Mehra, Anurag

2014-08-01

Magnetic nanoparticles (MNP's) have become increasingly important in heating applications such as hyperthermia treatment of cancer due to their ability to release heat when a remote external alternating magnetic field is applied. It has been shown that the heating capability of such particles varies significantly with the size of particles used. In this paper, we theoretically evaluate the heating capability of rod-shaped MNP's and identify conditions under which these particles display highest efficiency. For optimally sized monodisperse particles, the power generated by rod-shaped particles is found to be equal to that generated by spherical particles. However, for particles which are not mono dispersed, rod-shaped particles are found to be more effective in heating as a result of the greater spread in the power density distribution curve. Additionally, for rod-shaped particles, a dispersion in the radius of the particle contributes more to the reduction in loss power when compared to a dispersion in the length. We further identify the optimum size, i.e the radius and length of nanorods, given a bi-variate log-normal distribution of particle size in two dimensions.

Potential Application of a Thermoelectric Generator in Passive Cooling System of Nuclear Power Plants

NASA Astrophysics Data System (ADS)

Wang, Dongqing; Liu, Yu; Jiang, Jin; Pang, Wei; Lau, Woon Ming; Mei, Jun

2017-05-01

In the design of nuclear power plants, various natural circulation passive cooling systems are considered to remove residual heat from the reactor core in the event of a power loss and maintain the plant's safety. These passive systems rely on gravity differences of fluids, resulting from density differentials, rather than using an external power-driven system. Unfortunately, a major drawback of such systems is their weak driving force, which can negatively impact safety. In such systems, there is a temperature difference between the heat source and the heat sink, which potentially offers a natural platform for thermoelectric generator (TEG) applications. While a previous study designed and analyzed a TEG-based passive core cooling system, this paper considers TEG applications in other passive cooling systems of nuclear power plants, after which the concept of a TEG-based passive cooling system is proposed. In such a system, electricity is produced using the system's temperature differences through the TEG, and this electricity is used to further enhance the cooling process.

Power converter having improved terminal structure

DOEpatents

Radosevich, Lawrence D.; Kannenberg, Daniel G.; Phillips, Mark G.; Kaishian, Steven C.

2007-03-06

A terminal structure for power electronics circuits reduces the need for a DC bus and thereby the incidence of parasitic inductance. The structure is secured to a support that may receive one or more power electronic circuits. The support may aid in removing heat from the circuits through fluid circulating through the support. The support may form a shield from both external EMI/RFI and from interference generated by operation of the power electronic circuits. Features may be provided to permit and enhance connection of the circuitry to external circuitry, such as by direct contact between the terminal assembly and AC and DC circuit components. Modular units may be assembled that may be coupled to electronic circuitry via plug-in arrangements or through interface with a backplane or similar mounting and interconnecting structures.

Stirling heat pump external heat systems - An appliance perspective

NASA Astrophysics Data System (ADS)

Vasilakis, Andrew D.; Thomas, John F.

A major issue facing the Stirling Engine Heat Pump is system cost, and, in particular, the cost of the External Heat System (EHS). The need for high temperature at the heater head (600 C to 700 C) results in low combustion system efficiencies unless efficient heat recovery is employed. The balance between energy efficiency and use of costly high temperature materials is critical to design and cost optimization. Blower power consumption and NO(x) emissions are also important. A new approach to the design and cost optimization of the EHS was taken by viewing the system from a natural gas-fired appliance perspective. To develop a design acceptable to gas industry requirements, American National Standards Institute (ANSI) code considerations were incorporated into the design process and material selections. A parametric engineering design and cost model was developed to perform the analysis, including the impact of design on NO(x) emissions. Analysis results and recommended EHS design and material choices are given.

Stirling heat pump external heat systems: An appliance perspective

NASA Astrophysics Data System (ADS)

Vasilakis, A. D.; Thomas, J. F.

1992-08-01

A major issue facing the Stirling Engine Heat Pump is system cost, and, in particular, the cost of the External Heat System (EHS). The need for high temperature at the heater head (600 C to 700 C) results in low combustion system efficiencies unless efficient heat recovery is employed. The balance between energy efficiency and use of costly high temperature materials is critical to design and cost optimization. Blower power consumption and NO(x) emissions are also important. A new approach to the design and cost optimization of the EHS system was taken by viewing the system from a natural gas-fired appliance perspective. To develop a design acceptable to gas industry requirements, American National Standards Institute (ANSI) code considerations were incorporated into the design process and material selections. A parametric engineering design and cost model was developed to perform the analysis, including the impact of design on NO(x) emissions. Analysis results and recommended EHS design and material choices are given.

An experimental investigation of a thermoelectric power generation system with different cold-side heat dissipation

NASA Astrophysics Data System (ADS)

Li, Y. H.; Wu, Z. H.; Xie, H. Q.; Xing, J. J.; Mao, J. H.; Wang, Y. Y.; Li, Z.

2018-01-01

Thermoelectric generation technology has attracted increasing attention because of its promising applications. In this work, the heat transfer characteristics and the performance of a thermoelectric generator (TEG) with different cold-side heat dissipation intensity has been studied. By fixing the hot-side temperature of TEG, the effects of various external conditions including the flow rate and the inlet temperature of the cooling water flowing through the cold-sided heat sink have been investigated detailedly. It was showed that the output power and the efficiency of TEG increased with temperature different enlarged, whereas the efficiency of TEG reduced with flow rate increased. It is proposed that more heat taken by the cooling water is attributed to the efficiency decrease when the flow rate of the cooling water is increased. This study would provide fundamental understanding for the design of more refined thermoelectric generation systems.

Role of external torque in the formation of ion thermal internal transport barriers

NASA Astrophysics Data System (ADS)

Jhang, Hogun; Kim, S. S.; Diamond, P. H.

2012-04-01

We present an analytic study of the impact of external torque on the formation of ion internal transport barriers (ITBs). A simple analytic relation representing the effect of low external torque on transport bifurcations is derived based on a two field transport model of pressure and toroidal momentum density. It is found that the application of an external torque can either facilitate or hamper bifurcation in heat flux driven plasmas depending on its sign relative to the direction of intrinsic torque. The ratio between radially integrated momentum (i.e., external torque) density to power input is shown to be a key macroscopic control parameter governing the characteristics of bifurcation.

Vehicle drive module having improved EMI shielding

DOEpatents

Beihoff, Bruce C.; Kehl, Dennis L.; Gettelfinger, Lee A.; Kaishian, Steven C.; Phillips, Mark G.; Radosevich, Lawrence D.

2006-11-28

EMI shielding in an electric vehicle drive is provided for power electronics circuits and the like via a direct-mount reference plane support and shielding structure. The thermal support may receive one or more power electronic circuits. The support may aid in removing heat from the circuits through fluid circulating through the support. The support forms a shield from both external EMI/RFI and from interference generated by operation of the power electronic circuits. Features may be provided to permit and enhance connection of the circuitry to external circuitry, such as improved terminal configurations. Modular units may be assembled that may be coupled to electronic circuitry via plug-in arrangements or through interface with a backplane or similar mounting and interconnecting structures.

Flexible thermoelectric device to harvest waste heat from the laptop

NASA Astrophysics Data System (ADS)

Salhi, Imane; Belhora, Fouad; Hajjaji, Abdelowahed; Jay, Jacques; Boughaleb, Yahia

2017-05-01

Recovering waste heat from integrated circuits of a laptop using thermoelectricity effects seems to be an appropriate process to enhance its efficiency. Thermoelectricity, as an energy harvesting process, helps to gain on both sides: financially as it reduces the energy consumption and environmentally as it minimizes the carbon footprint. This paper presents a flexible thermoelectric generator module which is developed to harvest waste heat of the laptop to power up some external loads. First, a theoretical analysis of the system is provided where both thermal and electrical models are exposed. Second, an estimation of the power density harvested by only one thermoelectric leg is given. This estimation can reach 0.01 µW/cm2 and it is confirmed by a numerical simulation based on the finite element method. Afterwards, this power density is improved to become 0.4 µW/cm2 by adding a heat sink in the cold side showing that the thermal resistances of the air and of the heat sink play a crucial role in transferring the temperature gradient to the thermoelectric (TE) material. Finally, it is indicated that the power harvested can be enough to power up portion of the circuitry or other important micro-accessories by using numerous thermoelectric modules.

Heat engine development for solar thermal power systems

NASA Technical Reports Server (NTRS)

Pham, H. Q.; Jaffe, L. D.

1981-01-01

The technical status of three heat engines (Stirling, high-temperature Brayton, and Combined cycle) for use in solar thermal power systems is presented. Performance goals necessary to develop a system competitive with conventional power requirements include an external heated engine output less than 40 kW, and efficiency power conversion subsystem at least 40% at rated output, and a half-power efficiency of at least 37%. Results show that the Stirling engine can offer a 39% efficiency with 100 hours of life, and a 20% efficiency with 10,000 hours of life, but problems with seals and heater heads exist. With a demonstrated efficiency near 31% at 1500 F and a minimum lifetime of 100,000 hours, the Brayton engine does not offer sufficient engine lifetime, efficiency, and maintenance for solar thermal power systems. Examination of the Rankine bottoming cycle of the Combined cycle engine reveals a 30 year lifetime, but a low efficiency. Additional development of engines for solar use is primarily in the areas of components to provide a long lifetime, high reliability, and low maintenance (no more than $0.001/kW-hr).

Heat Pipes for Alaskan Oil

NASA Technical Reports Server (NTRS)

1976-01-01

McDonnel Douglas Corporation is using a heat-pipe device, developed through the space program, to transport oil from Alaska's rich North Slope fields. It is being used to keep the ground frozen along the 798- mile pipeline saving hundreds of millions of dollars and protecting the tundra environment. Heatpipes are totally automatic, they sense and respond to climatic conditions with no moving parts, require no external power, and never need adjustment or servicing.

Solar receiver performance of point focusing collector system

NASA Technical Reports Server (NTRS)

Wu, Y. C.; Wen, L. C.

1978-01-01

The solar receiver performance of cavity receivers and external receivers used in dispersed solar power systems was evaluated for the temperature range 300-1300 C. Several parameters of receiver and concentrator are examined. It was found that cavity receivers are generally more efficient than external receivers, especially at high temperatures which require a large heat transfer area. The effects of variation in the ratio of receiver area to aperture area are considered.

The nuclear battery

NASA Astrophysics Data System (ADS)

Kozier, K. S.; Rosinger, H. E.

The evolution and present status of an Atomic Energy of Canada Limited program to develop a small, solid-state, passively cooled reactor power supply known as the Nuclear Battery is reviewed. Key technical features of the Nuclear Battery reactor core include a heat-pipe primary heat transport system, graphite neutron moderator, low-enriched uranium TRISO coated-particle fuel and the use of burnable poisons for long-term reactivity control. An external secondary heat transport system extracts useful heat energy, which may be converted into electricity in an organic Rankine cycle engine or used to produce high-pressure steam. The present reference design is capable of producing about 2400 kW(t) (about 600 kW(e) net) for 15 full-power years. Technical and safety features are described along with recent progress in component hardware development programs and market assessment work.

High power densities from high-temperature materials interactions. [thermionic energy conversion and metallic fluid heat pipes

NASA Technical Reports Server (NTRS)

Morris, J. F.

1981-01-01

Thermionic energy converters and metallic-fluid heat pipes are well suited to serve together synergistically. The two operating cycles appear as simple and isolated as their material problems seem forebodingly deceptive and complicated. Simplified equations verify material properties and interactions as primary influences on the operational effectiveness of both. Each experiences flow limitations in thermal emission and vaporization because of temperature restrictions redounding from thermophysicochemical stability considerations. Topics discussed include: (1) successful limitation of alkali-metal corrosion; (2) protection against external hot corrosive gases; (3) coping with external and internal vaporization; (4) controlling interfacial reactions and diffusion; and (5) meeting other thermophysical challenges; expansion matches and creep.

External-cavity beam combining of 4-channel quantum cascade lasers

NASA Astrophysics Data System (ADS)

Zhao, Yue; Zhang, Jin-Chuan; Zhou, Yu-Hong; Jia, Zhi-Wei; Zhuo, Ning; Zhai, Shen-Qiang; Wang, Li-Jun; Liu, Jun-Qi; Liu, Shu-Man; Liu, Feng-Qi; Wang, Zhan-Guo

2017-09-01

We demonstrate an external-cavity (EC) beam combining of 4-channel quantum cascade lasers (QCLs) with an output coupler which makes different QCL beams propagating coaxially. A beam combining efficiency of 35% (up to 75% near threshold) is obtained with a beam quality M2 of 5.5. A peak power of 0.64 W is achieved at a wavelength of 4.7 μm. The differences of spot characteristic between coupled and uncoupled are also showed in this letter. The QCLs in this EC system do not have heat crosstalk so that the system can be used for high power beam combining of QCLs.

Fluid cooled vehicle drive module

DOEpatents

Beihoff, Bruce C.; Radosevich, Lawrence D.; Meyer, Andreas A.; Gollhardt, Neil; Kannenberg, Daniel G.

2005-11-15

An electric vehicle drive includes a support may receive one or more power electronic circuits. The support may aid in removing heat from the circuits through fluid circulating through the support. The support, in conjunction with other packaging features may form a shield from both external EM/RFI and from interference generated by operation of the power electronic circuits. Features may be provided to permit and enhance connection of the circuitry to external circuitry, such as improved terminal configurations. Modular units may be assembled that may be coupled to electronic circuitry via plug-in arrangements or through interface with a backplane or similar mounting and interconnecting structures.

Energy and environmental evaluation of combined cooling heating and power system

NASA Astrophysics Data System (ADS)

Bugaj, Andrzej

2017-11-01

The paper addresses issues involving problems of implementing combined cooling, heating and power (CCHP) system to industrial facility with well-defined demand profiles of cooling, heating and electricity. The application of CCHP system in this particular industrial facility is being evaluated by comparison with the reference system that consists of three conventional methods of energy supply: (a) electricity from external grid, (b) heat from gas-fired boilers and (c) cooling from vapour compression chillers run by electricity from the grid. The CCHP system scenario is based on the combined heat and power (CHP) plant with gas turbine-compressor arrangement and water/lithium bromide absorption chiller of a single-effect type. Those two scenarios are analysed in terms of annual primary energy usage as well as emissions of CO2. The results of the analysis show an extent of primary energy savings of the CCHP system in comparison with the reference system. Furthermore, the environmental impact of the CCHP usage, in the form of greenhouse gases emission reductions, compares quite favourably with the reference conventional option.

The advanced thermionic converter with microwave power as an auxiliary ionization source

NASA Technical Reports Server (NTRS)

Manikopoulos, C. N.; Hatziprocopiou, M.; Chiu, H. S.; Shaw, D. T.

1978-01-01

In the search for auxiliary sources of ionization for the advanced thermionic converter plasma, as required for terrestial applications, the use of externally applied microwave power is considered. The present work is part of the advanced model thermionic converter development research currently performed at the laboratory for Power and Environmental Studies at SUNY Buffalo. Microwave power in the frequency range 1-3 GHz is used to externally pump a thermionic converter and the results are compared to the theoretical model proposed by Lam (1976) in describing the thermionic converter plasma. The electron temperature of the plasma is found to be raised considerably by effective microwave heating which results in the disappearance of the double sheath ordinarily erected in front of the emitter. The experimental data agree satisfactorily with theory in the low current region.

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.

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.

Analysis of Turbulent Flow and Heat Transfer on a Flat Plate at High Mach Numbers with Variable Fluid Properties

NASA Technical Reports Server (NTRS)

Deissler, R. G.; Loeffler, A. L., Jr.

1959-01-01

A previous analysis of turbulent heat transfer and flow with variable fluid properties in smooth passages is extended to flow over a flat plate at high Mach numbers, and the results are compared with experimental data. Velocity and temperature distributions are calculated for a boundary layer with appreciative effects of frictional heating and external heat transfer. Viscosity and thermal conductivity are assumed to vary as a power or the temperature, while Prandtl number and specific heat are taken as constant. Skin-friction and heat-transfer coefficients are calculated and compared with the incompressible values. The rate of boundary-layer growth is obtained for various Mach numbers.

Artificial Aurora and Ionospheric Heating by HAARP

NASA Astrophysics Data System (ADS)

Hadavandkhani, S.; Nikouravan, Bijan; Ghazimaghrebi, F.

2016-08-01

A recent experiment was achieved at HAARP to study the scaling of the ionospherically generated ELF signal with power transmitted from the high frequency (HF) array. The results were in excellent agreement with computer simulations. The outcomes approving that the ELF power increases with the square of the incident HF power. This paper present a review on the situation of the ionized particles in Ionospheric layer when stimulated by artificial an ELF and VLF external high energy radio waves.

Efficiency optimization of a closed indirectly fired gas turbine cycle working under two variable-temperature heat reservoirs

NASA Astrophysics Data System (ADS)

Ma, Zheshu; Wu, Jieer

2011-08-01

Indirectly or externally fired gas turbines (IFGT or EFGT) are interesting technologies under development for small and medium scale combined heat and power (CHP) supplies in combination with micro gas turbine technologies. The emphasis is primarily on the utilization of the waste heat from the turbine in a recuperative process and the possibility of burning biomass even "dirty" fuel by employing a high temperature heat exchanger (HTHE) to avoid the combustion gases passing through the turbine. In this paper, finite time thermodynamics is employed in the performance analysis of a class of irreversible closed IFGT cycles coupled to variable temperature heat reservoirs. Based on the derived analytical formulae for the dimensionless power output and efficiency, the efficiency optimization is performed in two aspects. The first is to search the optimum heat conductance distribution corresponding to the efficiency optimization among the hot- and cold-side of the heat reservoirs and the high temperature heat exchangers for a fixed total heat exchanger inventory. The second is to search the optimum thermal capacitance rate matching corresponding to the maximum efficiency between the working fluid and the high-temperature heat reservoir for a fixed ratio of the thermal capacitance rates of the two heat reservoirs. The influences of some design parameters on the optimum heat conductance distribution, the optimum thermal capacitance rate matching and the maximum power output, which include the inlet temperature ratio of the two heat reservoirs, the efficiencies of the compressor and the gas turbine, and the total pressure recovery coefficient, are provided by numerical examples. The power plant configuration under optimized operation condition leads to a smaller size, including the compressor, turbine, two heat reservoirs and the HTHE.

User's manual for PRESTO: A computer code for the performance of regenerative steam turbine cycles

NASA Technical Reports Server (NTRS)

Fuller, L. C.; Stovall, T. K.

1979-01-01

Standard turbine cycles for baseload power plants and cycles with such additional features as process steam extraction and induction and feedwater heating by external heat sources may be modeled. Peaking and high back pressure cycles are also included. The code's methodology is to use the expansion line efficiencies, exhaust loss, leakages, mechanical losses, and generator losses to calculate the heat rate and generator output. A general description of the code is given as well as the instructions for input data preparation. Appended are two complete example cases.

A Concept of Thermographic Method for Non-Destructive Testing of Polymeric Composite Structures Using Self-Heating Effect

PubMed Central

2017-01-01

Traditional techniques of active thermography require an external source of energy used for excitation, usually in the form of high power lamps or ultrasonic devices. In this paper, the author presents an alternative approach based on the self-heating effect observable in polymer-based structures during cyclic loading. The presented approach is based on, firstly, determination of bending resonance frequencies of a tested structure, and then, on excitation of a structure with a multi-harmonic signal constructed from the harmonics with frequencies of determined resonances. Following this, heating-up of a tested structure occurs in the location of stress concentration and mechanical energy dissipation due to the viscoelastic response of a structure. By applying multi-harmonic signal, one ensures coverage of the structure by such heated regions. The concept is verified experimentally on artificially damaged composite specimens. The results demonstrate the presented approach and indicate its potential, especially when traditional methods of excitation with an external structure for thermographic inspection cannot be applied. PMID:29283430

A Concept of Thermographic Method for Non-Destructive Testing of Polymeric Composite Structures Using Self-Heating Effect.

PubMed

Katunin, Andrzej

2017-12-28

Traditional techniques of active thermography require an external source of energy used for excitation, usually in the form of high power lamps or ultrasonic devices. In this paper, the author presents an alternative approach based on the self-heating effect observable in polymer-based structures during cyclic loading. The presented approach is based on, firstly, determination of bending resonance frequencies of a tested structure, and then, on excitation of a structure with a multi-harmonic signal constructed from the harmonics with frequencies of determined resonances. Following this, heating-up of a tested structure occurs in the location of stress concentration and mechanical energy dissipation due to the viscoelastic response of a structure. By applying multi-harmonic signal, one ensures coverage of the structure by such heated regions. The concept is verified experimentally on artificially damaged composite specimens. The results demonstrate the presented approach and indicate its potential, especially when traditional methods of excitation with an external structure for thermographic inspection cannot be applied.

Vehicle drive module having improved terminal design

DOEpatents

Beihoff, Bruce C.; Radosevich, Lawrence D.; Phillips, Mark G.; Kehl, Dennis L.; Kaishian, Steven C.; Kannenberg, Daniel G.

2006-04-25

A terminal structure for vehicle drive power electronics circuits reduces the need for a DC bus and thereby the incidence of parasitic inductance. The structure is secured to a support that may receive one or more power electronic circuits. The support may aid in removing heat from the circuits through fluid circulating through the support. The support may form a shield from both external EMI/RFI and from interference generated by operation of the power electronic circuits. Features may be provided to permit and enhance connection of the circuitry to external circuitry, such as by direct contact between the terminal assembly and AC and DC circuit components. Modular units may be assembled that may be coupled to electronic circuitry via plug-in arrangements or through interface with a backplane or similar mounting and interconnecting structures.

Grumman evaluates Space Station thermal control and power systems

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

Kandebo, S.W.

1985-09-01

Attention is given to the definition of requirements for the NASA Space Station's electrical power and thermal control systems, which must be highly dependable to minimize the need for external support and will embody a highly flexible modular design concept. Module maintenance will be performed by in-orbit replacement of failed modules, and energy storage system growth will be accomplished by the incorporation of additional modules. Both photovoltaic and solar heat-driven electrical generator concepts are under consideration as the basis of the power system.

Method for optical pumping of thin laser media at high average power

DOEpatents

Zapata, Luis E [Livermore, CA; Beach, Raymond J [Livermore, CA; Honea, Eric C [Sunol, CA; Payne, Stephen A [Castro Valley, CA

2004-07-13

A thin, planar laser material is bonded to a light guide of an index-matched material forming a composite disk. Diode array or other pump light is introduced into the composite disk through the edges of the disk. Pump light trapped within the composite disk depletes as it multi-passes the laser medium before reaching an opposing edge of the disk. The resulting compound optical structure efficiently delivers concentrated pump light and to a laser medium of minimum thickness. The external face of the laser medium is used for cooling. A high performance cooler attached to the external face of the laser medium rejects heat. Laser beam extraction is parallel to the heat flux to minimize optical distortions.

Capacity Loss Studies on High Capacity Li-ion Cells for the Orbiter Advanced Hydraulic Power System

NASA Technical Reports Server (NTRS)

Jeevarajan, Judith A.; Irlbeck, Bradley W.

2004-01-01

Contents include the following: Introduction. Physical and electrochemical characteristics. Performance evaluation. Rate performance. Internal resistance. Performance at different temperatures. Safety evaluation. Overcharge. Overdischarge. External short. Simulated internal short. Heat-to-vent. Vibration. Drop rest. Vent and burst pressure.

A Total Cost of Ownership Model for Low Temperature PEM Fuel Cells in Combined Heat and Power and Backup Power Applications

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

University of California, Berkeley; Wei, Max; Lipman, Timothy

2014-06-23

A total cost of ownership model is described for low temperature proton exchange membrane stationary fuel cell systems for combined heat and power (CHP) applications from 1-250kW and backup power applications from 1-50kW. System designs and functional specifications for these two applications were developed across the range of system power levels. Bottom-up cost estimates were made for balance of plant costs, and detailed direct cost estimates for key fuel cell stack components were derived using design-for-manufacturing-and-assembly techniques. The development of high throughput, automated processes achieving high yield are projected to reduce the cost for fuel cell stacks to the $300/kWmore » level at an annual production volume of 100 MW. Several promising combinations of building types and geographical location in the U.S. were identified for installation of fuel cell CHP systems based on the LBNL modelling tool DER CAM. Life-cycle modelling and externality assessment were done for hotels and hospitals. Reduced electricity demand charges, heating credits and carbon credits can reduce the effective cost of electricity ($/kWhe) by 26-44percent in locations such as Minneapolis, where high carbon intensity electricity from the grid is displaces by a fuel cell system operating on reformate fuel. This project extends the scope of existing cost studies to include externalities and ancillary financial benefits and thus provides a more comprehensive picture of fuel cell system benefits, consistent with a policy and incentive environment that increasingly values these ancillary benefits. The project provides a critical, new modelling capacity and should aid a broad range of policy makers in assessing the integrated costs and benefits of fuel cell systems versus other distributed generation technologies.« less

Nuclear Power - Post Fukushima

NASA Astrophysics Data System (ADS)

Reyes, Jose, Jr.

2011-10-01

The extreme events that led to the prolonged power outage at the Fukushima Daiicchi nuclear plant have highlighted the importance of assuring a means for stable long term cooling of the nuclear fuel and containment following a complete station blackout. Legislative bodies, regulatory agencies and industry are drawing lessons from those events and considering what changes, if any, are needed to nuclear power, post Fukushima. The enhanced safety of a new class of reactor designed by NuScale Power is drawing significant attention in light of the Fukushima events. During normal operation, each NuScale containment is fully immersed in a water-filled stainless steel lined concrete pool that resides underground. The pool, housed in a Seismic Category I building, is large enough to provided 30 days of core and containment cooling without adding water. After 30 days, the decay heat generations coupled with thermal radiation heat transfer is completely adequate to remove core decay heat for an unlimited period of time. These passive power systems can perform their function without requiring an external supply of water of power. An assessment of the NuScale passive systems is being performed through a comprehensive test program that includes the NuScale integral system test facility at Oregon State University

Closed bore XMR (CBXMR) systems for aortic valve replacement: Investigation of rotating-anode x-ray tube heat loadability

PubMed Central

Bracken, John A.; Lillaney, Prasheel V.; Fahrig, Rebecca; Rowlands, J. A.

2008-01-01

In order to improve the safety and efficacy of percutaneous aortic valve replacement procedures, a closed bore hybrid x-ray∕MRI (CBXMR) system is proposed in which an x-ray C-arm will be positioned with its isocenter ≈1 m from the entrance of a clinical MRI scanner. This system will harness the complementary strengths of both modalities to improve clinical outcome. A key component of the CBXMR system will be a rotating anode x-ray tube to produce high-quality x-ray images. There are challenges in positioning an x-ray tube in the magnetic fringe field of the MRI magnet. Here, the effects of an external magnetic field on x-ray tube induction motors of radiography x-ray tubes and the corresponding reduction of x-ray tube heat loadability are investigated. Anode rotation frequency fanode was unaffected when the external magnetic field Bb was parallel to the axis of rotation of the anode but decreased when Bb was perpendicular to the axis of rotation. The experimental fanode values agreed with predicted values to within ±3% over a Bb range of 0–30 mT. The MRI fringe field at the proposed location of the x-ray tube mounted on the C-arm (≈4 mT) reduced fanode by only 1%, so x-ray tube heat loadability will not be compromised when using CBXMR systems for percutaneous aortic valve replacement procedures. Eddy current heating power in the rotor due to an MRI fringe field was found to be two orders of magnitude weaker than the heating power produced on the anode due to a fluoroscopic exposure, so eddy current heating had no effect on x-ray tube heat loadability. PMID:18841857

Apparatus and method for pyroelectric power conversion

DOEpatents

Olsen, Randall B.

1984-01-01

Apparatus and method for converting heat to electrical energy by the use of one or more capacitors having temperature dependent capacitance. The capacitor is cycled between relatively high and relatively low temperatures by successive thermal contact with relatively high and relatively low temperature portions of a heat transfer medium having a temperature gradient therein. Upon heating of the capacitor, the capacitance thereof is reduced, so that a charge therein is caused to expand into associated external circuitry in which it is available to do electrical work. The capacitor is then cooled and recharged and the cycle is repeated. The electrical output of the capacitor results from the regenerative delivery of heat to and removal of heat from the capacitor by the heat transfer medium, and efficient conversion of heat to electric energy is thereby effected.

Modeling of SBS Phase Conjugation in Multimode Step Index Fibers

DTIC Science & Technology

2008-03-01

cavity or in an external amplifier. Since pumping is never a perfectly efficient process, some heat will be introduced, and for very high pump powers...modes it supports, and the incident pump power. While theoretical investigations of SBS PCMs have been conducted by a num- ber of authors, the model...predictions about the phase conjugate fidelity that could be expected from a given pump intensity input coupled into a specific fiber. A numerical

Measuring Subsurface Water Fluxes Using a Heat Pulse Sensor

NASA Astrophysics Data System (ADS)

Ochsner, T. E.; Wang, Q.; Horton, R.

2001-12-01

Subsurface water flux is an important parameter in studies of runoff, infiltration, groundwater recharge, and subsurface chemical transport. Heat pulse sensors have been proposed as promising tools for measuring subsurface water fluxes. Our heat pulse probe consists of three 4-cm stainless-steel needles embedded in a waterproof epoxy body. The needles contain resistance heaters and thermocouples. The probes are connected to an external datalogger and power supply and then installed in soil. To measure the water flux, a 15-s heat pulse is generated at the middle needle using the power supply and the resistance heater, and the temperature increases at the needles 6-mm upstream and downstream from the heater are recorded using the thermocouples and datalogger. To date, heat pulse methods have required cumbersome mathematical analysis to calculate soil water flux from this measured data. We present a new mathematical analysis showing that a simple relationship exists between water flux and the ratio of the temperature increase downstream from the line heat source to the temperature increase upstream from the line heat source. The simplicity of this relationship makes heat pulse sensors a more attractive option for measuring subsurface water fluxes.

Practical results of heat conservation in a housing estate scale-actions implemented by the Pradnik-Bialy-Zachod housing cooperative in Cracow

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

Piotrowski, L.

1995-12-31

There are 11,600,000 apartments occupied in Poland. More than 7,700,000 of these apartments are located in towns. Energy consumption for heating, ventilation and district hot water in residential housing reaches 40% of the national power balance. A portion of district heat distribution and relatively low energy efficiency is characteristic for Polish residential housing. Seventy five percent of apartments in towns are provided with central heating installations and 55% of the entire heat demand in Polish buildings is covered by district heating systems. The total installed heat power of these systems reaches 46,000 MW. The situation with regard to conservation inmore » Polish residential housing is directly related to the legacy of central planning of the national economy and to the current phase of its re-organization to the market-oriented system. The standard value of the overall heat-transfer coefficient for external walls in Poland until 1980 was 1.16 W/m{sup 2}K; at present it is reduced to 0.55 W/m{sup 2}K. There are numerous reasons for the low energy efficiency in residential housing. These reasons are discussed.« less

Investigation of solid nitrogen for cryogenic thermal storage in superconducting cable terminations for enhanced resiliency

NASA Astrophysics Data System (ADS)

Suttell, N.; Zhang, Z.; Kweon, J.; Nes, T.; Kim, C. H.; Pamidi, S.; Ordonez, J. C.

2017-12-01

Low heat capacity of helium makes the helium gas cooled high temperature superconducting (HTS) power devices susceptible to large temperature rises during unexpected heat loads such as electrical faults or cryogenic system failures. Cryogenic thermal storage in the form of solid nitrogen designed in the terminations is explored as a means to increase the thermal stability and operational time of HTS power cables in the event of unexpected heat loads. An external tank containing activated charcoal is used as an adsorption buffer tank for nitrogen gas. The use of activated charcoal minimizes the volume of the buffer tank and prevents pressure rises during melting and boiling of the solid nitrogen. Calculations of the cryogenic thermal storage needed and a description of the experimental setup used to understand the design constraints are discussed.

Ionosphere-thermosphere energy budgets for the ICME storms of March 2013 and 2015 estimated with GITM and observational proxies

NASA Astrophysics Data System (ADS)

Verkhoglyadova, O. P.; Meng, X.; Mannucci, A. J.; Mlynczak, M. G.; Hunt, L. A.; Lu, G.

2017-09-01

The ionosphere-thermosphere (IT) energy partitioning for the interplanetary coronal mass ejection (ICME) storms of 16-19 March 2013 and 2015 is estimated with the Global Ionosphere-Thermosphere Model (GITM), empirical models and proxies derived from in situ measurements. We focus on auroral heating, Joule heating, and thermospheric cooling. Solar wind data, F10.7, OVATION Prime model and the Weimer 2005 model are used to drive GITM from above. Thermospheric nitric oxide and carbon dioxide cooling emission powers and fluxes are estimated from TIMED/SABER measurements. Assimilative mapping of ionospheric electrodynamics (AMIE) estimations of hemispheric power and Joule heating are presented, based on data from global magnetometers, the AMPERE magnetic field data, SSUSI auroral images, and the SuperDARN radar network. Modeled Joule heating and auroral heating of the IT system are mostly controlled by external driving in the March 2013 and 2015 storms, while NO cooling persists into the storm recovery phase. The total heating in the model is about 1000 GW to 3000 GW. Additionally, we intercompare contributions in selected energy channels for five coronal mass ejection-type storms modeled with GITM. Modeled auroral heating shows reasonable agreement with AMIE hemispheric power and is higher than other observational proxies. Joule heating and infrared cooling are likely underestimated in GITM. We discuss challenges and discrepancies in estimating and global modeling of the IT energy partitioning, especially Joule heating, during geomagnetic storms.

Non-equilibrium quantum heat machines

NASA Astrophysics Data System (ADS)

Alicki, Robert; Gelbwaser-Klimovsky, David

2015-11-01

Standard heat machines (engine, heat pump, refrigerator) are composed of a system (working fluid) coupled to at least two equilibrium baths at different temperatures and periodically driven by an external device (piston or rotor) sometimes called the work reservoir. The aim of this paper is to go beyond this scheme by considering environments which are stationary but cannot be decomposed into a few baths at thermal equilibrium. Such situations are important, for example in solar cells, chemical machines in biology, various realizations of laser cooling or nanoscopic machines driven by laser radiation. We classify non-equilibrium baths depending on their thermodynamic behavior and show that the efficiency of heat machines powered by them is limited by the generalized Carnot bound.

Effect of ECRH and resonant magnetic fields on formation of magnetic islands in the T-10 tokamak plasma

NASA Astrophysics Data System (ADS)

Shestakov, E. A.; Savrukhin, P. V.

2017-10-01

Experiments in the T-10 tokamak demonstrated possibility of controlling the plasma current during disruption instability using the electron cyclotron resonance heating (ECRH) and the controlled operation of the ohmic current-holding system. Quasistable plasma discharge with repeating sawtooth oscillations can be restored after energy quench using auxiliary ECRH power when PEC / POH > 2-5. The external magnetic field generation system consisted of eight saddle coils that were arranged symmetrically relative to the equatorial plane of the torus outside of the vacuum vessel of the T-10 tokamak to study the possible resonant magnetic field effects on the rotation frequency of magnetic islands. The saddle coils power supply system is based on four thyristor converters with a total power of 300 kW. The power supply control system is based on Siemens S7 controllers. As shown by preliminary experiments, the interaction efficiency of external magnetic fields with plasma depends on the plasma magnetic configuration. Optimal conditions for slowing the rotation of magnetic islands were determined. Additionally, the direction of the error magnetic field in the T-10 tokamak was determined, and the threshold value of the external magnetic field was determined.

Joule-Heated Molten Regolith Electrolysis Reactor Concepts for Oxygen and Metals Production on the Moon and Mars

NASA Technical Reports Server (NTRS)

Sibille, Laurent; Dominques, Jesus A.

2012-01-01

The maturation of Molten Regolith Electrolysis (MRE) as a viable technology for oxygen and metals production on explored planets relies on the realization of the self-heating mode for the reactor. Joule heat generated during regolith electrolysis creates thermal energy that should be able to maintain the molten phase (similar to electrolytic Hall-Heroult process for aluminum production). Self-heating via Joule heating offers many advantages: (1) The regolith itself is the crucible material, it protects the vessel walls (2) Simplifies the engineering of the reactor (3) Reduces power consumption (no external heating) (4) Extends the longevity of the reactor. Predictive modeling is a tool chosen to perform dimensional analysis of a self-heating reactor: (1) Multiphysics modeling (COMSOL) was selected for Joule heat generation and heat transfer (2) Objective is to identify critical dimensions for first reactor prototype.

Compact vehicle drive module having improved thermal control

DOEpatents

Meyer, Andreas A.; Radosevich, Lawrence D.; Beihoff, Bruce C.; Kehl, Dennis L.; Kannenberg, Daniel G.

2006-01-03

An electric vehicle drive includes a thermal support may receive one or more power electronic circuits. The support may aid in removing heat from the circuits through fluid circulating through the support, which may be controlled in a closed-loop manner. Interfacing between circuits, circuit mounting structure, and the support provide for greatly enhanced cooling. The support may form a shield from both external EMI/RFI and from interference generated by operation of the power electronic circuits. Features may be provided to permit and enhance connection of the circuitry to external circuitry, such as improved terminal configurations. Modular units may be assembled that may be coupled to electronic circuitry via plug-in arrangements or through interface with a backplane or similar mounting and interconnecting structures.

Apparatus and method for pyroelectric power conversion

DOEpatents

Olsen, R.B.

1984-01-10

Apparatus and method for converting heat to electrical energy by the use of one or more capacitors having temperature dependent capacitance are disclosed. The capacitor is cycled between relatively high and relatively low temperatures by successive thermal contact with relatively high and relatively low temperature portions of a heat transfer medium having a temperature gradient therein. Upon heating of the capacitor, the capacitance thereof is reduced, so that a charge therein is caused to expand into associated external circuitry in which it is available to do electrical work. The capacitor is then cooled and recharged and the cycle is repeated. The electrical output of the capacitor results from the regenerative delivery of heat to and removal of heat from the capacitor by the heat transfer medium, and efficient conversion of heat to electric energy is thereby effected. 12 figs.

Medical devices utilizing optical fibers for simultaneous power, communications and control

DOEpatents

Fitch, Joseph P.; Matthews, Dennis L.; Hagans, Karla G.; Lee, Abraham P.; Krulevitch, Peter; Benett, William J.; Clough, Robert E.; DaSilva, Luiz B.; Celliers, Peter M.

2003-06-10

A medical device is constructed in the basic form of a catheter having a distal end for insertion into and manipulation within a body and a proximal end providing for a user to control the manipulation of the distal end within the body. A fiberoptic cable is disposed within the catheter and having a distal end proximate to the distal end of the catheter and a proximal end for external coupling of laser light energy. A laser-light-to-mechanical-power converter is connected to receive light from the distal end of the fiber optic cable and may include a photo-voltaic cell and an electromechanical motor or a heat-sensitive photo-thermal material. An electronic sensor is connected to receive electrical power from said distal end of the fiberoptic cable and is connected to provide signal information about a particular physical environment and communicated externally through the fiberoptic cable to the proximal end thereof. A mechanical sensor is attached to the distal end of the fiberoptic cable and connected to provide light signal information about a particular physical environment and communicated externally through the fiberoptic cable.

Mathematical Analysis of High-Temperature Co-electrolysis of CO2 and O2 Production in a Closed-Loop Atmosphere Revitalization System

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

Michael G. McKellar; Manohar S. Sohal; Lila Mulloth

2010-03-01

NASA has been evaluating two closed-loop atmosphere revitalization architectures based on Sabatier and Bosch carbon dioxide, CO2, reduction technologies. The CO2 and steam, H2O, co-electrolysis process is another option that NASA has investigated. Utilizing recent advances in the fuel cell technology sector, the Idaho National Laboratory, INL, has developed a CO2 and H2O co-electrolysis process to produce oxygen and syngas (carbon monoxide, CO and hydrogen, H2 mixture) for terrestrial (energy production) application. The technology is a combined process that involves steam electrolysis, CO2 electrolysis, and the reverse water gas shift (RWGS) reaction. A number of process models have been developedmore » and analyzed to determine the theoretical power required to recover oxygen, O2, in each case. These models include the current Sabatier and Bosch technologies and combinations of those processes with high-temperature co-electrolysis. The cases of constant CO2 supply and constant O2 production were evaluated. In addition, a process model of the hydrogenation process with co-electrolysis was developed and compared. Sabatier processes require the least amount of energy input per kg of oxygen produced. If co-electrolysis replaces solid polymer electrolyte (SPE) electrolysis within the Sabatier architecture, the power requirement is reduced by over 10%, but only if heat recuperation is used. Sabatier processes, however, require external water to achieve the lower power results. Under conditions of constant incoming carbon dioxide flow, the Sabatier architectures require more power than the other architectures. The Bosch, Boudouard with co-electrolysis, and the hydrogenation with co-electrolysis processes require little or no external water. The Bosch and hydrogenation processes produce water within their reactors, which aids in reducing the power requirement for electrolysis. The Boudouard with co-electrolysis process has a higher electrolysis power requirement because carbon dioxide is split instead of water, which has a lower heat of formation. Hydrogenation with co-electrolysis offers the best overall power performance for two reasons: it requires no external water, and it produces its own water, which reduces the power requirement for co-electrolysis.« less

Multi-stage circulating fluidized bed syngas cooling

DOEpatents

Liu, Guohai; Vimalchand, Pannalal; Guan, Xiaofeng; Peng, WanWang

2016-10-11

A method and apparatus for cooling hot gas streams in the temperature range 800.degree. C. to 1600.degree. C. using multi-stage circulating fluid bed (CFB) coolers is disclosed. The invention relates to cooling the hot syngas from coal gasifiers in which the hot syngas entrains substances that foul, erode and corrode heat transfer surfaces upon contact in conventional coolers. The hot syngas is cooled by extracting and indirectly transferring heat to heat transfer surfaces with circulating inert solid particles in CFB syngas coolers. The CFB syngas coolers are staged to facilitate generation of steam at multiple conditions and hot boiler feed water that are necessary for power generation in an IGCC process. The multi-stage syngas cooler can include internally circulating fluid bed coolers, externally circulating fluid bed coolers and hybrid coolers that incorporate features of both internally and externally circulating fluid bed coolers. Higher process efficiencies can be realized as the invention can handle hot syngas from various types of gasifiers without the need for a less efficient precooling step.

Novel Self-Heated Gas Sensors Using on-Chip Networked Nanowires with Ultralow Power Consumption.

PubMed

Tan, Ha Minh; Manh Hung, Chu; Ngoc, Trinh Minh; Nguyen, Hugo; Duc Hoa, Nguyen; Van Duy, Nguyen; Hieu, Nguyen Van

2017-02-22

The length of single crystalline nanowires (NWs) offers a perfect pathway for electron transfer, while the small diameter of the NWs hampers thermal losses to tje environment, substrate, and metal electrodes. Therefore, Joule self-heating effect is nearly ideal for operating NW gas sensors at ultralow power consumption, without additional heaters. The realization of the self-heated NW sensors using the "pick and place" approach is complex, hardly reproducible, low yield, and not applicable for mass production. Here, we present the sensing capability of the self-heated networked SnO 2 NWs effectively prepared by on-chip growth. Our developed self-heated sensors exhibit a good response of 25.6 to 2.5 ppm NO 2 gas, while the response to 500 ppm H 2 , 100 ppm NH 3 , 100 ppm H 2 S, and 500 ppm C 2 H 5 OH is very low, indicating the good selectivity of the sensors to NO 2 gas. Furthermore, the detection limit is very low, down to 82 parts-per-trillion. As-obtained sensing performance under self-heating mode is nearly identical to that under external heating mode. While the power consumption under self-heating mode is extremely low, around hundreds of microwatts, as scaled-down the size of the electrode is below 10 μm. The selectivity of the sensors can be controlled simply by tuning the loading power that enables simple detection of NO 2 in mixed gases. Remarkable performance together with a significantly facile fabrication process of the present sensors enhances the potential application of NW sensors in next generation technologies such as electronic noses, the Internet of Things, and smartphone sensing.

Deposition of diamond-like films by ECR microwave plasma

NASA Technical Reports Server (NTRS)

Shing, Yuh-Han (Inventor); Pool, Frederick S. (Inventor)

1995-01-01

Hard amorphous hydrogenated carbon, diamond-like films are deposited using an electron cyclotron resonance microwave plasma with a separate radio frequency power bias applied to a substrate stage. The electron cyclotron resonance microwave plasma yields low deposition pressure and creates ion species otherwise unavailable. A magnetic mirror configuration extracts special ion species from a plasma chamber. Different levels of the radio frequency power bias accelerate the ion species of the ECR plasma impinging on a substrate to form different diamond-like films. During the deposition process, a sample stage is maintained at an ambient temperature of less than 100.degree. C. No external heating is applied to the sample stage. The deposition process enables diamond-like films to be deposited on heat-sensitive substrates.

Personal, closed-cycle cooling and protective apparatus and thermal battery therefor

DOEpatents

Klett, James W.; Klett, Lynn B.

2004-07-20

A closed-cycle apparatus for cooling a living body includes a heat pickup body or garment which permits evaporation of an evaporating fluid, transmission of the vapor to a condenser, and return of the condensate to the heat pickup body. A thermal battery cooling source is provided for removing heat from the condenser. The apparatus requires no external power and provides a cooling system for soldiers, race car drivers, police officers, firefighters, bomb squad technicians, and other personnel who may utilize protective clothing to work in hostile environments. An additional shield layer may simultaneously provide protection from discomfort, illness or injury due to harmful atmospheres, projectiles, edged weapons, impacts, explosions, heat, poisons, microbes, corrosive agents, or radiation, while simultaneously removing body heat from the wearer.

Heterogonous Nanofluids for Nuclear Power Plants

NASA Astrophysics Data System (ADS)

Alammar, Khalid

2014-09-01

Nuclear reactions can be associated with high heat energy release. Extracting such energy efficiently requires the use of high-rate heat exchangers. Conventional heat transfer fluids, such as water and oils are limited in their thermal conductivity, and hence nanofluids have been introduced lately to overcome such limitation. By suspending metal nanoparticles with high thermal conductivity in conventional heat transfer fluids, thermal conductivity of the resulting homogeneous nanofluid is increased. Heterogeneous nanofluids offer yet more potential for heat transfer enhancement. By stratifying nanoparticles within the boundary layer, thermal conductivity is increased where temperature gradients are highest, thereby increasing overall heat transfer of a flowing fluid. In order to test the merit of this novel technique, a numerical study of a laminar pipe flow of a heterogeneous nanofluid was conducted. Effect of Iron-Oxide distribution on flow and heat transfer characteristics was investigated. With Iron-Oxide volume concentration of 0.009 in water, up to 50% local heat transfer enhancement was predicted for the heterogeneous compared to homogeneous nanofluids. Increasing the Reynolds number is shown to increase enhancement while having negligible effect on pressure drop. Using permanent magnets attached externally to the pipe, an experimental investigation conducted at MIT nuclear reactor laboratory for similar flow characteristics of a heterogeneous nanofluid have shown upto 160% enhancement in heat transfer. Such results show that heterogeneous nanofluids are promising for augmenting heat transfer rates in nuclear power heat exchanger systems.

Terrestrial Applications of Extreme Environment Stirling Space Power Systems

NASA Technical Reports Server (NTRS)

Dyson, Rodger. W.

2012-01-01

NASA has been developing power systems capable of long-term operation in extreme environments such as the surface of Venus. This technology can use any external heat source to efficiently provide electrical power and cooling; and it is designed to be extremely efficient and reliable for extended space missions. Terrestrial applications include: use in electric hybrid vehicles; distributed home co-generation/cooling; and quiet recreational vehicle power generation. This technology can reduce environmental emissions, petroleum consumption, and noise while eliminating maintenance and environmental damage from automotive fluids such as oil lubricants and air conditioning coolant. This report will provide an overview of this new technology and its applications.

High performance protection circuit for power electronics applications

NASA Astrophysics Data System (ADS)

Tudoran, Cristian D.; Dǎdârlat, Dorin N.; Toşa, Nicoleta; Mişan, Ioan

2015-12-01

In this paper we present a high performance protection circuit designed for the power electronics applications where the load currents can increase rapidly and exceed the maximum allowed values, like in the case of high frequency induction heating inverters or high frequency plasma generators. The protection circuit is based on a microcontroller and can be adapted for use on single-phase or three-phase power systems. Its versatility comes from the fact that the circuit can communicate with the protected system, having the role of a "sensor" or it can interrupt the power supply for protection, in this case functioning as an external, independent protection circuit.

Improvement in magnetic field immunity of externally-coupled transcutaneous energy transmission system for a totally implantable artificial heart.

PubMed

Yamamoto, Takahiko; Koshiji, Kohji; Homma, Akihiko; Tatsumi, Eisuke; Taenaka, Yoshiyuki

2008-01-01

Transcutaneous energy transmission (TET) that uses electromagnetic induction between the external and internal coils of a transformer is the most promising method to supply driving energy to a totally implantable artificial heart without invasion. Induction-heating (IH) cookers generate magnetic flux, and if a cooker is operated near a transcutaneous transformer, the magnetic flux generated will link with the external and internal coils of the transcutaneous transformer. This will affect the performance of the TET and the artificial heart system. Hence, it is necessary to improve the magnetic field immunity of the TET system. During operation of the system, if the transcutaneous transformer is in close proximity to an IH cooker, the electric power generated by the cooker and coupled to the transformer can drive the artificial heart system. To prevent this coupling, the external coil was shielded with a conductive shield that had a slit in it. This reduces the coupling between the transformer and the magnetic field generated by the induction cooker. However, the temperature of the shield increased due to heating by eddy currents. The temperature of the shield can be reduced by separating the IH cooker and the shield.

Irreversible and endoreversible behaviors of the LD-model for heat devices: the role of the time constraints and symmetries on the performance at maximum χ figure of merit

NASA Astrophysics Data System (ADS)

Gonzalez-Ayala, Julian; Calvo Hernández, A.; Roco, J. M. M.

2016-07-01

The main unified energetic properties of low dissipation heat engines and refrigerator engines allow for both endoreversible or irreversible configurations. This is accomplished by means of the constraints imposed on the characteristic global operation time or the contact times between the working system with the external heat baths and modulated by the dissipation symmetries. A suited unified figure of merit (which becomes power output for heat engines) is analyzed and the influence of the symmetries on the optimum performance discussed. The obtained results, independent on any heat transfer law, are faced with those obtained from Carnot-like heat models where specific heat transfer laws are needed. Thus, it is shown that only the inverse phenomenological law, often used in linear irreversible thermodynamics, correctly reproduces all optimized values for both the efficiency and coefficient of performance values.

Another self-similar blast wave: Early time asymptote with shock heated electrons and high thermal conductivity

NASA Technical Reports Server (NTRS)

Cox, D. P.; Edgar, R. J.

1982-01-01

Accurate approximations are presented for the self-similar structures of nonradiating blast waves with adiabatic ions, isothermal electrons, and equation ion and electron temperatures at the shock. The cases considered evolve in cavities with power law ambient densities (including the uniform density case) and have negligible external pressure. The results provide the early time asymptote for systems with shock heating of electrons and strong thermal conduction. In addition, they provide analytical results against which two fluid numerical hydrodynamic codes can be checked.

A review on lithium-ion power battery thermal management technologies and thermal safety

NASA Astrophysics Data System (ADS)

An, Zhoujian; Jia, Li; Ding, Yong; Dang, Chao; Li, Xuejiao

2017-10-01

Lithium-ion power battery has become one of the main power sources for electric vehicles and hybrid electric vehicles because of superior performance compared with other power sources. In order to ensure the safety and improve the performance, the maximum operating temperature and local temperature difference of batteries must be maintained in an appropriate range. The effect of temperature on the capacity fade and aging are simply investigated. The electrode structure, including electrode thickness, particle size and porosity, are analyzed. It is found that all of them have significant influences on the heat generation of battery. Details of various thermal management technologies, namely air based, phase change material based, heat pipe based and liquid based, are discussed and compared from the perspective of improving the external heat dissipation. The selection of different battery thermal management (BTM) technologies should be based on the cooling demand and applications, and liquid cooling is suggested being the most suitable method for large-scale battery pack charged/discharged at higher C-rate and in high-temperature environment. The thermal safety in the respect of propagation and suppression of thermal runaway is analyzed.

Renal hemodynamic effects of activation of specific renal sympathetic nerve fiber groups.

PubMed

DiBona, G F; Sawin, L L

1999-02-01

To examine the effect of activation of a unique population of renal sympathetic nerve fibers on renal blood flow (RBF) dynamics, anesthetized rats were instrumented with a renal sympathetic nerve activity (RSNA) recording electrode and an electromagnetic flow probe on the ipsilateral renal artery. Peripheral thermal receptor stimulation (external heat) was used to activate a unique population of renal sympathetic nerve fibers and to increase total RSNA. Total RSNA was reflexly increased to the same degree with somatic receptor stimulation (tail compression). Arterial pressure and heart rate were increased by both stimuli. Total RSNA was increased to the same degree by both stimuli but external heat produced a greater renal vasoconstrictor response than tail compression. Whereas both stimuli increased spectral density power of RSNA at both cardiac and respiratory frequencies, modulation of RBF variability by fluctuations of RSNA was small at these frequencies, with values for the normalized transfer gain being approximately 0.1 at >0.5 Hz. During tail compression coherent oscillations of RSNA and RBF were found at 0.3-0.4 Hz with normalized transfer gain of 0.33 +/- 0.02. During external heat coherent oscillations of RSNA and RBF were found at both 0.2 and 0.3-0.4 Hz with normalized transfer gains of 0. 63 +/- 0.05 at 0.2 Hz and 0.53 +/- 0.04 to 0.36 +/- 0.02 at 0.3-0.4 Hz. Renal denervation eliminated the oscillations in RBF at both 0.2 and 0.3-0.4 Hz. These findings indicate that despite similar increases in total RSNA, external heat results in a greater renal vasoconstrictor response than tail compression due to the activation of a unique population of renal sympathetic nerve fibers with different frequency-response characteristics of the renal vasculature.

Thermal Management Architecture for Future Responsive Spacecraft

NASA Astrophysics Data System (ADS)

Bugby, D.; Zimbeck, W.; Kroliczek, E.

2009-03-01

This paper describes a novel thermal design architecture that enables satellites to be conceived, configured, launched, and operationally deployed very quickly. The architecture has been given the acronym SMARTS for Satellite Modular and Reconfigurable Thermal System and it involves four basic design rules: modest radiator oversizing, maximum external insulation, internal isothermalization and radiator heat flow modulation. The SMARTS philosophy is being developed in support of the DoD Operationally Responsive Space (ORS) initiative which seeks to drastically improve small satellite adaptability, deployability, and design flexibility. To illustrate the benefits of the philosophy for a prototypical multi-paneled small satellite, the paper describes a SMARTS thermal control system implementation that uses: panel-to-panel heat conduction, intra-panel heat pipe isothermalization, radiator heat flow modulation via a thermoelectric cooler (TEC) cold-biased loop heat pipe (LHP) and maximum external multi-layer insulation (MLI). Analyses are presented that compare the traditional "cold-biasing plus heater power" passive thermal design approach to the SMARTS approach. Plans for a 3-panel SMARTS thermal test bed are described. Ultimately, the goal is to incorporate SMARTS into the design of future ORS satellites, but it is also possible that some aspects of SMARTS technology could be used to improve the responsiveness of future NASA spacecraft. [22 CFR 125.4(b)(13) applicable

The Stirling Engine: A Wave of the Future

NASA Technical Reports Server (NTRS)

1992-01-01

This video describes the Stirling engine, an external combustion engine which creates heat energy to power the motor, and can use many types of fuel. It can be used for both stationary and propulsion purposes and has advantages of better fuel economy and cleaner exhaust than internal combustion engines. The engine is shown being road tested at Langley Air Force Base.

Evaluating Stellarator Divertor Designs with EMC3

NASA Astrophysics Data System (ADS)

Bader, Aaron; Anderson, D. T.; Feng, Y.; Hegna, C. C.; Talmadge, J. N.

2013-10-01

In this paper various improvements of stellarator divertor design are explored. Next step stellarator devices require innovative divertor solutions to handle heat flux loads and impurity control. One avenue is to enhance magnetic flux expansion near strike points, somewhat akin to the X-Divertor concept in Tokamaks. The effect of judiciously placed external coils on flux deposition is calculated for configurations based on the HSX stellarator. In addition, we attempt to optimize divertor plate location to facilitate the external coil placement. Alternate areas of focus involve altering edge island size to elucidate the driving physics in the edge. The 3-D nature of stellarators complicates design and necessitates analysis of new divertor structures with appropriate simulation tools. We evaluate the various configurations with the coupled codes EMC3-EIRENE, allowing us to benchmark configurations based on target heat flux, impurity behavior, radiated power, and transitions to high recycling and detached regimes. Work supported by DOE-SC0006103.

Harvesting dissipated energy with a mesoscopic ratchet

NASA Astrophysics Data System (ADS)

Roche, B.; Roulleau, P.; Jullien, T.; Jompol, Y.; Farrer, I.; Ritchie, D. A.; Glattli, D. C.

2015-04-01

The search for new efficient thermoelectric devices converting waste heat into electrical energy is of major importance. The physics of mesoscopic electronic transport offers the possibility to develop a new generation of nanoengines with high efficiency. Here we describe an all-electrical heat engine harvesting and converting dissipated power into an electrical current. Two capacitively coupled mesoscopic conductors realized in a two-dimensional conductor form the hot source and the cold converter of our device. In the former, controlled Joule heating generated by a voltage-biased quantum point contact results in thermal voltage fluctuations. By capacitive coupling the latter creates electric potential fluctuations in a cold chaotic cavity connected to external leads by two quantum point contacts. For unequal quantum point contact transmissions, a net electrical current is observed proportional to the heat produced.

High performance protection circuit for power electronics applications

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

Tudoran, Cristian D., E-mail: cristian.tudoran@itim-cj.ro; Dădârlat, Dorin N.; Toşa, Nicoleta

2015-12-23

In this paper we present a high performance protection circuit designed for the power electronics applications where the load currents can increase rapidly and exceed the maximum allowed values, like in the case of high frequency induction heating inverters or high frequency plasma generators. The protection circuit is based on a microcontroller and can be adapted for use on single-phase or three-phase power systems. Its versatility comes from the fact that the circuit can communicate with the protected system, having the role of a “sensor” or it can interrupt the power supply for protection, in this case functioning as anmore » external, independent protection circuit.« less

Transient Thermal Analyses of Passive Systems on SCEPTOR X-57

NASA Technical Reports Server (NTRS)

Chin, Jeffrey C.; Schnulo, Sydney L.; Smith, Andrew D.

2017-01-01

As efficiency, emissions, and noise become increasingly prominent considerations in aircraft design, turning to an electric propulsion system is a desirable solution. Achieving the intended benefits of distributed electric propulsion (DEP) requires thermally demanding high power systems, presenting a different set of challenges compared to traditional aircraft propulsion. The embedded nature of these heat sources often preclude the use of traditional thermal management systems in order to maximize performance, with less opportunity to exhaust waste heat to the surrounding environment. This paper summarizes the thermal analyses of X-57 vehicle subsystems that don't employ externally air-cooled heat sinks. The high-power battery, wires, high-lift motors, and aircraft outer surface are subjected to heat loads with stringent thermal constraints. The temperature of these components are tracked transiently, since they never reach a steady-state equilibrium. Through analysis and testing, this report demonstrates that properly characterizing the material properties is key to accurately modeling peak temperature of these systems, with less concern for spatial thermal gradients. Experimentally validated results show the thermal profile of these systems can be sufficiently estimated using reduced order approximations.

Characteristics and performance of the variable polarity plasma arc welding process used in the Space Shuttle external tank

NASA Technical Reports Server (NTRS)

Hung, R. J.; Lee, C. C.; Liu, J. W.

1990-01-01

Significant advantages of the Variable Polarity Plasma Arc (VPPA) Welding Process include faster welding, fewer repairs, less joint preparation, reduced weldment distortion, and absence of porosity. Flow profiles and power distribution of argon plasma gas as a working fluid to produce plasma arc jet in the VPPA welding process was analyzed. Major loss of heat transfer for flow through the nozzle is convective heat transfer; for the plasma jet flow between the outlet of the nozzle and workpiece is radiative heat transfer; and for the flow through the keyhole of the workpiece is convective heat transfer. The majority of the power absorbed by the keyhole of the workpiece is used for melting the solid metal workpiece into a molten metallic puddle. The crown and root widths and the crown and root heights can be predicted. An algorithm for promoting automatic control of flow parameters and the dimensions of the final product of the welding specification to be used for the VPPA Welding System operated at MSFC are provided.

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.

Locked-mode avoidance and recovery without momentum input

NASA Astrophysics Data System (ADS)

Delgado-Aparicio, L.; Rice, J. E.; Wolfe, S.; Cziegler, I.; Gao, C.; Granetz, R.; Wukitch, S.; Terry, J.; Greenwald, M.; Sugiyama, L.; Hubbard, A.; Hugges, J.; Marmar, E.; Phillips, P.; Rowan, W.

2015-11-01

Error-field-induced locked-modes (LMs) have been studied in Alcator C-Mod at ITER-Bϕ, without NBI fueling and momentum input. Delay of the mode-onset and locked-mode recovery has been successfully obtained without external momentum input using Ion Cyclotron Resonance Heating (ICRH). The use of external heating in-sync with the error-field ramp-up resulted in a successful delay of the mode-onset when PICRH > 1 MW, which demonstrates the existence of a power threshold to ``unlock'' the mode; in the presence of an error field the L-mode discharge can transition into H-mode only when PICRH > 2 MW and at high densities, avoiding also the density pump-out. The effects of ion heating observed on unlocking the core plasma may be due to ICRH induced flows in the plasma boundary, or modifications of plasma profiles that changed the underlying turbulence. This work was performed under US DoE contracts including DE-FC02-99ER54512 and others at MIT, DE-FG03-96ER-54373 at University of Texas at Austin, and DE-AC02-09CH11466 at PPPL.

A method to minimise the fading effects of LiF:Mg,Ti (TLD-600 and TLD-700) using a pre-heat technique.

PubMed

Lee, YoungJu; Won, Yuho; Kang, Kidoo

2015-04-01

Passive integrating dosemeters [thermoluminescent dosimeter (TLD) and optically stimulated luminescence (OSL)] are the only legally permitted individual dosemeters for occupational external radiation exposure monitoring in Korea. Also its maximum issuing cycle does not exceed 3 months, and the Korean regulations require personal dosemeters for official assessment of external radiation exposure to be issued by an approved or rather an accredited dosimetry service according to ISO/IEC 17025. KHNP (Korea Hydro & Nuclear Power, LTD), a unique operating company of nuclear power plants (NPPs) in Korea, currently has a plan to extend a TLD issuing cycle from 1 to 3 months under the authors' fading error criteria, ±10%. The authors have performed a feasibility study that minimises post-irradiation fading effects within their maximum reading cycle employing pre-heating technique. They repeatedly performed irradiation/reading a bare TLD chip to determine optimum pre-heating conditions by analysing each glow curve. The optimum reading conditions within the maximum reading cycle of 3 months were decided: a pre-heating temperature of 165°C, a pre-heating time of 9 s, a heating rate of 25°C s(-1), a reading temperature of 300°C and an acquisition time of 10 s. The fading result of TLD-600 and TLD-700 carried by newly developed time temperature profile (TTP) showed a much smaller fading effect than that of current TTP. The result showed that the fading error due to a developed TTP resulted in a ∼5% signal loss, whereas a current TTP caused a ∼15% loss. The authors also carried out a legal performance test on newly developed TTP to confirm its possibility as an official dosemeter. The legal performance tests that applied the developed TTP satisfied the criteria for all the test categories. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Probabilistic models to estimate fire-induced cable damage at nuclear power plants

NASA Astrophysics Data System (ADS)

Valbuena, Genebelin R.

Even though numerous PRAs have shown that fire can be a major contributor to nuclear power plant risk, there are some specific areas of knowledge related to this issue, such as the prediction of fire-induced damage to electrical cables and circuits, and their potential effects in the safety of the nuclear power plant, that still constitute a practical enigma, particularly for the lack of approaches/models to perform consistent and objective assessments. This report contains a discussion of three different models to estimate fire-induced cable damage likelihood given a specified fire profile: the kinetic, the heat transfer and the IR "K Factor" model. These models not only are based on statistical analysis of data available in the open literature, but to the greatest extent possible they use physics based principles to describe the underlying mechanism of failures that take place among the electrical cables upon heating due to external fires. The characterization of cable damage, and consequently the loss of functionality of electrical cables in fire is a complex phenomenon that depends on a variety of intrinsic factors such as cable materials and dimensions, and extrinsic factors such as electrical and mechanical loads on the cables, heat flux severity, and exposure time. Some of these factors are difficult to estimate even in a well-characterized fire, not only for the variability related to the unknown material composition and physical arrangements, but also for the lack of objective frameworks and theoretical models to study the behavior of polymeric wire cable insulation under dynamic external thermal insults. The results of this research will (1) help to develop a consistent framework to predict fire-induced cable failure modes likelihood, and (2) develop some guidance to evaluate and/or reduce the risk associated with these failure modes in existing and new power plant facilities. Among the models evaluated, the physics-based heat transfer model takes into account the properties and characteristics of the cables and cable materials, and the characteristics of the thermal insult. This model can be used to estimate the probability of cable damage under different thermal conditions.

Induction Hardening of External Gear

NASA Astrophysics Data System (ADS)

Bukanin, V. A.; Ivanov, A. N.; Zenkov, A. E.; Vologdin, V. V.; Vologdin, V. V., Jr.

2018-03-01

Problems and solution of gear induction hardening are described. Main attention is paid to the parameters of heating and cooling systems. ELTA 7.0 program has been used to obtain the required electrical parameters of inductor, power sources, resonant circuits, as well as to choose the quenching media. Comparison of experimental and calculated results of investigation is provided. In order to compare advantages and disadvantages of single- and dual-frequency heating processes, many variants of these technologies were simulated. The predicted structure and hardness of steel gears are obtained by use of the ELTA data base taken into account the Continuous Cooling Transformation diagrams.

Analysis of heat-transfer measurements from 2 AEDC wind tunnels on the Shuttle external tank

NASA Technical Reports Server (NTRS)

Nutt, K. W.

1984-01-01

Previous aerodynamic heating tests have been conducted in the AEDC/VKF Supersonic Wind Tunnel (A) to aid in defining the design thermal environment for the space shuttle external tank. The quality of these data has been under discussion because of the effects of low tunnel enthalpy and slow model injection rates. Recently the AEDC/VKF Hypersonic Wind Tunnel (C) has been modified to provide a Mach 4 capability that has significantly higher tunnel enthalpy with more rapid model injection rates. Tests were conducted in Tunnel C at Mach 4 to obtain data on the external tank for comparison with Tunnel A results. Data were obtained on a 0.0175 scale model of the Space Shuttle Integrated Vehicle at Re/ft = 4 x 10 to the 6th power with the tunnel stagnation temperature varying from 740 to 1440 R. Model attitude varied from an angle of attack of -5 to 5 deg and an angle of sideslip of -3 to 3 deg. One set of data was obtained in Tunnel C at Re/ft = 6.9 x 10 to the 6th for comparison with flight data. Data comparisons between the two tunnels for numerous regions on the external tank are given.

Coupling of a 2.5 kW steam reformer with a 1 kW el PEM fuel cell

NASA Astrophysics Data System (ADS)

Mathiak, J.; Heinzel, A.; Roes, J.; Kalk, Th.; Kraus, H.; Brandt, H.

The University of Duisburg-Essen has developed a compact multi-fuel steam reformer suitable for natural gas, propane and butane. This steam reformer was combined with a polymer electrolyte membrane fuel cell (PEM FC) and a system test of the process chain was performed. The fuel processor comprises a prereformer step, a primary reformer, water gas shift reactors, a steam generator, internal heat exchangers in order to achieve an optimised heat integration and an external burner for heat supply as well as a preferential oxidation step (PROX) as CO purification. The fuel processor is designed to deliver a thermal hydrogen power output from 500 W to 2.5 kW. The PEM fuel cell stack provides about 1 kW electrical power. In the following paper experimental results of measurements of the single components PEM fuel cell and fuel processor as well as results of the coupling of both to form a process chain are presented.

Infrared thermography non-destructive evaluation of lithium-ion battery

NASA Astrophysics Data System (ADS)

Wang, Zi-jun; Li, Zhi-qiang; Liu, Qiang

2011-08-01

The power lithium-ion battery with its high specific energy, high theoretical capacity and good cycle-life is a prime candidate as a power source for electric vehicles (EVs) and hybrid electric vehicles (HEVs). Safety is especially important for large-scale lithium-ion batteries, especially the thermal analysis is essential for their development and design. Thermal modeling is an effective way to understand the thermal behavior of the lithium-ion battery during charging and discharging. With the charging and discharging, the internal heat generation of the lithium-ion battery becomes large, and the temperature rises leading to an uneven temperature distribution induces partial degradation. Infrared (IR) Non-destructive Evaluation (NDE) has been well developed for decades years in materials, structures, and aircraft. Most thermographic methods need thermal excitation to the measurement structures. In NDE of battery, the thermal excitation is the heat generated from carbon and cobalt electrodes in electrolyte. A technique named "power function" has been developed to determine the heat by chemical reactions. In this paper, the simulations of the transient response of the temperature distribution in the lithium-ion battery are developed. The key to resolving the security problem lies in the thermal controlling, including the heat generation and the internal and external heat transfer. Therefore, three-dimensional modelling for capturing geometrical thermal effects on battery thermal abuse behaviour is required. The simulation model contains the heat generation during electrolyte decomposition and electrical resistance component. Oven tests are simulated by three-dimensional model and the discharge test preformed by test system. Infrared thermography of discharge is recorded in order to analyze the security of the lithium-ion power battery. Nondestructive detection is performed for thermal abuse analysis and discharge analysis.

Design of Heat Exchanger for Ericsson-Brayton Piston Engine

PubMed Central

Durcansky, Peter; Papucik, Stefan; Jandacka, Jozef

2014-01-01

Combined power generation or cogeneration is a highly effective technology that produces heat and electricity in one device more efficiently than separate production. Overall effectiveness is growing by use of combined technologies of energy extraction, taking heat from flue gases and coolants of machines. Another problem is the dependence of such devices on fossil fuels as fuel. For the combustion turbine is mostly used as fuel natural gas, kerosene and as fuel for heating power plants is mostly used coal. It is therefore necessary to seek for compensation today, which confirms the assumption in the future. At first glance, the obvious efforts are to restrict the use of largely oil and change the type of energy used in transport. Another significant change is the increase in renewable energy—energy that is produced from renewable sources. Among machines gaining energy by unconventional way belong mainly the steam engine, Stirling engine, and Ericsson engine. In these machines, the energy is obtained by external combustion and engine performs work in a medium that receives and transmits energy from combustion or flue gases indirectly. The paper deals with the principle of hot-air engines, and their use in combined heat and electricity production from biomass and with heat exchangers as primary energy transforming element. PMID:24977174

Design of heat exchanger for Ericsson-Brayton piston engine.

PubMed

Durcansky, Peter; Papucik, Stefan; Jandacka, Jozef; Holubcik, Michal; Nosek, Radovan

2014-01-01

Combined power generation or cogeneration is a highly effective technology that produces heat and electricity in one device more efficiently than separate production. Overall effectiveness is growing by use of combined technologies of energy extraction, taking heat from flue gases and coolants of machines. Another problem is the dependence of such devices on fossil fuels as fuel. For the combustion turbine is mostly used as fuel natural gas, kerosene and as fuel for heating power plants is mostly used coal. It is therefore necessary to seek for compensation today, which confirms the assumption in the future. At first glance, the obvious efforts are to restrict the use of largely oil and change the type of energy used in transport. Another significant change is the increase in renewable energy--energy that is produced from renewable sources. Among machines gaining energy by unconventional way belong mainly the steam engine, Stirling engine, and Ericsson engine. In these machines, the energy is obtained by external combustion and engine performs work in a medium that receives and transmits energy from combustion or flue gases indirectly. The paper deals with the principle of hot-air engines, and their use in combined heat and electricity production from biomass and with heat exchangers as primary energy transforming element.

The study of the mobile compressor unit heat losses recovery system waste heat exchanger thermal insulation types influence on the operational efficiency

NASA Astrophysics Data System (ADS)

Yusha, V. L.; Chernov, G. I.; Kalashnikov, A. M.

2017-08-01

The paper examines the mobile compressor unit (MCU) heat losses recovery system waste heat exchanger prototype external thermal insulation types influence on the operational efficiency. The study is conducted by means of the numerical method through the modellingof the heat exchange processes carried out in the waste heat exchanger in ANSUS. Thermaflex, mineral wool, penofol, water and air were applied as the heat exchanger external insulation. The study results showed the waste heat exchanger external thermal insulationexistence or absence to have a significant impact on the heat exchanger operational efficiency.

Numerical investigation of plasma edge transport and limiter heat fluxes in Wendelstein 7-X startup plasmas with EMC3-EIRENE

NASA Astrophysics Data System (ADS)

Effenberg, F.; Feng, Y.; Schmitz, O.; Frerichs, H.; Bozhenkov, S. A.; Hölbe, H.; König, R.; Krychowiak, M.; Pedersen, T. Sunn; Reiter, D.; Stephey, L.; W7-X Team

2017-03-01

The results of a first systematic assessment of plasma edge transport processes for the limiter startup configuration at Wendelstein 7-X are presented. This includes an investigation of transport from intrinsic and externally injected impurities and their impact on the power balance and limiter heat fluxes. The fully 3D coupled plasma fluid and kinetic neutral transport Monte Carlo code EMC3-EIRENE is used. The analysis of the magnetic topology shows that the poloidally and toroidally localized limiters cause a 3D helical scrape-off layer (SOL) consisting of magnetic flux tubes of three different connection lengths L C. The transport in the helical SOL is governed by L C as topological scale length for the parallel plasma loss channel to the limiters. A clear modulation of the plasma pressure with L C is seen. The helical flux tube topology results in counter streaming sonic plasma flows. The heterogeneous SOL plasma structure yields an uneven limiter heat load distribution with localized peaking. Assuming spatially constant anomalous transport coefficients, increasing plasma density yields a reduction of the maximum peak heat loads from 12 MWm-2 to 7.5 MWm-2 and a broadening of the deposited heat fluxes. The impact of impurities on the limiter heat loads is studied by assuming intrinsic carbon impurities eroded from the limiter surfaces with a gross chemical sputtering yield of 2 % . The resulting radiative losses account for less than 10% of the input power in the power balance with marginal impact on the limiter heat loads. It is shown that a significant mitigation of peak heat loads, 40-50%, can be achieved with controlled impurity seeding with nitrogen and neon, which is a method of particular interest for the later island divertor phase.

The Physics of Energy

NASA Astrophysics Data System (ADS)

Jaffe, Robert L.; Taylor, Washington

2018-01-01

Part I. Basic Energy Physics and Uses: 1. Introduction; 2. Mechanical energy; 3. Electromagnetic energy; 4. Waves and light; 5. Thermodynamics I: heat and thermal energy; 6. Heat transfer; 7. Introduction to quantum physics; 8. Thermodynamics II: entropy and temperature; 9. Energy in matter; 10. Thermal energy conversion; 11. Internal combustion engines; 12. Phase-change energy conversion; 13. Thermal power and heat extraction cycles; Part II. Energy Sources: 14. The forces of nature; 15. Quantum phenomena in energy systems; 16. An overview of nuclear power; 17. Structure, properties and decays of nuclei; 18. Nuclear energy processes: fission and fusion; 19. Nuclear fission reactors and nuclear fusion experiments; 20. Ionizing radiation; 21. Energy in the universe; 22. Solar energy: solar production and radiation; 23. Solar energy: solar radiation on Earth; 24. Solar thermal energy; 25. Photovoltaic solar cells; 26. Biological energy; 27. Ocean energy flow; 28. Wind: a highly variable resource; 29. Fluids – the basics; 30. Wind turbines; 31. Energy from moving water: hydro, wave, tidal, and marine current power; 32. Geothermal energy; 33. Fossil fuels; Part III. Energy System Issues and Externalities: 34. Energy and climate; 35. Earth's climate: past, present, and future; 36. Energy efficiency, conservation, and changing energy sources; 37. Energy storage; 38. Electricity generation and transmission.

Cycle Analysis of a New Air Engine Design

NASA Astrophysics Data System (ADS)

Attar, Wiam Fadi

This thesis investigates a new externally heated engine design being developed by Soony Systems Inc. to serve as the prime mover in a residential-scale combined heat and power system. This is accomplished by developing a thermodynamic model for the engine and sweeping through the design parameter space in order to identify designs that maximize power output, efficiency, and brake mean effective pressure (BMEP). It was discovered that the original engine design was flawed so a new design was proposed and analyzed. The thermodynamic model was developed in four stages. The first model was quasi-static while the other three were time-dependent and used increasingly realistic models of the heat exchangers. For the range of design parameters investigated here, the peak power output is 6.8 kW, the peak efficiency is approximately 60%, and the peak BMEP is 389 kPa. These performance levels are compared to those of other closed-cycle engines. The results suggest that the Soony engine has the potential to be more efficient than Stirlings because it more closely approximates the Carnot cycle, but this comes at the cost of significantly lower BMEP (389 kPa vs. 2,760 kPa for the SOLO Stirling engine).

Startup of air-cooled condensers and dry cooling towers at low temperatures of the cooling air

NASA Astrophysics Data System (ADS)

Milman, O. O.; Ptakhin, A. V.; Kondratev, A. V.; Shifrin, B. A.; Yankov, G. G.

2016-05-01

The problems of startup and performance of air-cooled condensers (ACC) and dry cooling towers (DCT) at low cooling air temperatures are considered. Effects of the startup of the ACC at sub-zero temperatures are described. Different options of the ACC heating up are analyzed, and examples of existing technologies are presented (electric heating, heating up with hot air or steam, and internal and external heating). The use of additional heat exchanging sections, steam tracers, in the DCT design is described. The need for high power in cases of electric heating and heating up with hot air is noted. An experimental stand for research and testing of the ACC startup at low temperatures is described. The design of the three-pass ACC unit is given, and its advantages over classical single-pass design at low temperatures are listed. The formation of ice plugs inside the heat exchanging tubes during the start-up of ACC and DCT at low cooling air temperatures is analyzed. Experimental data on the effect of the steam flow rate, steam nozzle distance from the heat-exchange surface, and their orientation in space on the metal temperature were collected, and test results are analyzed. It is noted that the surface temperature at the end of the heat up is almost independent from its initial temperature. Recommendations for the safe start-up of ACCs and DCTs are given. The heating flow necessary to sufficiently heat up heat-exchange surfaces of ACCs and DCTs for the safe startup is estimated. The technology and the process of the heat up of the ACC with the heating steam external supply are described by the example of the startup of the full-scale section of the ACC at sub-zero temperatures of the cooling air, and the advantages of the proposed start-up technology are confirmed.

Alternating magnetic field optimization for IONP hyperthermia cancer treatment

NASA Astrophysics Data System (ADS)

Kastner, Elliot J.; Reeves, Russell; Bennett, William; Misra, Aditi; Petryk, Jim D.; Petryk, Alicia A.; Hoopes, P. Jack

2015-03-01

Iron oxide nanoparticles (IONP) have therapeutic potential to deliver a thermal dose to tumors when activated in an alternating magnetic field (AMF). Through various targeting methods such as antibody labeling or injection site choice, delivery of IONPs to tumors yields enhanced treatment accuracy and efficacy. Despite this advantage, delivery an AMF, which is sufficient to result in clinically relevant IONP heating, can result in nonspecific tissue heating via the generation of eddy currents and tissue permeated by local electric fields (joule heating). The production of eddy current heating is a function of tissue size, geometry and composition as well as coil design and operation. The purpose of this research is to increase the level of energy deposited into the IONPs versus the non-target tissue (power ratio/PR)1 in order to improve target heating and reduce nonspecific tissue damage. We propose to improve the PR using two primary concepts: (1) reduce power deposition into non-target tissue by manipulating the fields and eddy current flow and (2) enhance heat removal from non-target tissue. We have shown that controlling tissue placement within the AMF field, accounting for tissue geometry, utilizing external cooling devices, and modifying the field properties can decrease non-target heating by more than 50%, at clinically relevant AMF levels, thereby allowing for an increase in thermal dose to the tumor and increasing the therapeutic ratio.

Results of Steam-Water-Oxygen Treatment of the Inside of Heating Surfaces in Heat-Recovery Steam Generators of the PGU-800 Power Unit at the Perm' District Thermal Power Station

NASA Astrophysics Data System (ADS)

Ovechkina, O. V.; Zhuravlev, L. S.; Drozdov, A. A.; Solomeina, S. V.

2018-05-01

Prestarting, postinstallation steam-water-oxygen treatment (SWOT) of the natural circulation/steam reheat heat-recovery steam generators (HRSG) manufactured by OAO Krasny Kotelshchik was performed at the PGU-800 power unit of the Perm District Thermal Power Station (GRES). Prior to SWOT, steam-oxygen cleaning, passivation, and preservation of gas condensate heaters (GCH) of HRSGs were performed for 10 h using 1.3MPa/260°C/70 t/h external steam. After that, test specimens were cut out that demonstrated high strength of the passivating film. SWOT of the inside of the heating surfaces was carried out during no-load operation of the gas turbine unit with an exhaust temperature of 280-300°C at the HRSG inlet. The steam turbine was shutdown, and the generated steam was discharged into the atmosphere. Oxygen was metered into the discharge pipeline of the electricity-driven feed pumps and downcomers of the evaporators. The behavior of the concentration by weight of iron compounds and the results of investigation of cutout specimens by the drop or potentiometric method indicate that the steam-water-oxygen process makes it possible to remove corrosion products and reduce the time required to put a boiler into operation. Unlike other processes, SWOT does not require metal-intensive cleaning systems, temporary metering stations, and structures for collection of the waste solution.

Numerical investigation of the staged gasification of wet wood

NASA Astrophysics Data System (ADS)

Donskoi, I. G.; Kozlov, A. N.; Svishchev, D. A.; Shamanskii, V. A.

2017-04-01

Gasification of wooden biomass makes it possible to utilize forestry wastes and agricultural residues for generation of heat and power in isolated small-scale power systems. In spite of the availability of a huge amount of cheap biomass, the implementation of the gasification process is impeded by formation of tar products and poor thermal stability of the process. These factors reduce the competitiveness of gasification as compared with alternative technologies. The use of staged technologies enables certain disadvantages of conventional processes to be avoided. One of the previously proposed staged processes is investigated in this paper. For this purpose, mathematical models were developed for individual stages of the process, such as pyrolysis, pyrolysis gas combustion, and semicoke gasification. The effect of controlling parameters on the efficiency of fuel conversion into combustible gases is studied numerically using these models. For the controlling parameter are selected heat inputted into a pyrolysis reactor, the excess of oxidizer during gas combustion, and the wood moisture content. The process efficiency criterion is the gasification chemical efficiency accounting for the input of external heat (used for fuel drying and pyrolysis). The generated regime diagrams represent the gasification efficiency as a function of controlling parameters. Modeling results demonstrate that an increase in the fraction of heat supplied from an external source can result in an adequate efficiency of the wood gasification through the use of steam generated during drying. There are regions where it is feasible to perform incomplete combustion of the pyrolysis gas prior to the gasification. The calculated chemical efficiency of the staged gasification is as high as 80-85%, which is 10-20% higher that in conventional single-stage processes.

A Thermoelectric Energy Harvesting System for Powering Wireless Sensors in Nuclear Power Plants

NASA Astrophysics Data System (ADS)

Chen, Jie; Klein, Jackson; Wu, Yongjia; Xing, Shaoxu; Flammang, Robert; Heibel, Michael; Zuo, Lei

2016-10-01

Safety is the most important issue in the development of nuclear energy. This paper reports experimental studies of a thermoelectric energy harvesting system designed for integration in a nuclear power plant capable of performing in radiation rich environments and producing enough power to run wireless sensors meant to increase plant safety. Furthermore, the system, which utilizes wasted heat present in coolant system piping, has the unique ability to provide power in both normal and accidental situations, to run the sensors without the need for external power. Two energy harvesting prototypes were designed utilizing a heat pipe for heat transfer. The first can supply a maximum power of 2.25 W using two Bi2Te3 thermoelectric modules of 2.79cm (1.1") × 2.79 cm (1.1”), in a source temperature near 250 °C. A second design was put forward to extend the application in higher-temperature primary loops, in which one PbTe-Bi2Te3 hybrid TEG module of 5.6cm (2.2") × 5.6 cm (2.2") can provide a power of 3.0 W when the hot side temperature reaches 340 °C. In addition to the energy harvester, wireless communication circuits were developed along with an integrated power management circuit for wireless data transmission. A high intensity gamma radiation experiment was conducted during which each component was irradiated. A total dose of 200 kGy±10% (20M rads) was applied to the first prototype in order to approximate the expected lifetime accumulation for one implemented thermoelectric generator. Results showed that thermoelectric modules used in the prototype had no reduction in voltage output throughout irradiation. Throughout the experiment the harvester system witnessed a small voltage drop in open circuit voltage attributed to a reduction in heat pipe performance from radiation exposure. We also acquired a baseline radiation survivability level for non-hardened, non-shielded electronics of 102 Gy.

Developing Antitumor Magnetic Hyperthermia: Principles, Materials and Devices.

PubMed

Tishin, Alexander M; Shtil, Alexander A; Pyatakov, Alexander P; Zverev, Vladimir I

2016-01-01

Methods of local or loco-regional anticancer treatment are of the utmost importance because the therapeutic 'power' is applied directly to the disease site. Consequently, general toxicity is minimized. Hyperthermia, that is, a sustained increase of intratumoral temperature up to 45oC, has been investigated as a perspective treatment modality alone and/or in combination with ionizing radiation or chemotherapy. Still, the surrounding tissues can be damaged by the external heat. Development of new materials and devices gave rise to methods of inducing hyperthermia by a high frequency magnetic or electromagnetic field applied to the tumor with exogenous nanosized particles captured within it. The idea of this approach is the release of local heat in the vicinity of the magnetic nanoparticle in a time-varying magnetic field due to transfer of external magnetic field energy into the heat. Therefore, tumor cells are heated whereas the peritumoral non-malignant tissues are spared. This review analyzes recent advances in understanding physical principles that underlie magnetic hyperthermia as well as novel approaches to obtain nanoparticles with optimized physico-chemical, toxicological and tumoricidal properties. Special focus is made on the construction of devices for therapeutic purposes. The review covers recent patents and general literature sources regarding magnetic hyperthermia, the developing approach to treat otherwise intractable malignancies. </p><p>.

Overview of NASA Lewis Research Center free-piston Stirling engine technology activities applicable to space power systems

NASA Technical Reports Server (NTRS)

Slaby, Jack G.

1987-01-01

A brief overview is presented of the development and technological activities of the free-piston Stirling engine. The engine started as a small scale fractional horsepower engine which demonstrated basic engine operating principles and the advantages of being hermetically sealed, highly efficient, and simple. It eventually developed into the free piston Stirling engine driven heat pump, and then into the SP-100 Space Reactor Power Program from which came the Space Power Demonstrator Engine (SPDE). The SPDE successfully operated for over 300 hr and delivered 20 kW of PV power to an alternator plunger. The SPDE demonstrated that a dynamic power conversion system can, with proper design, be balanced; and the engine performed well with externally pumped hydrostatic gas bearings.

Optical arc sensor using energy harvesting power source

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

Choi, Kyoo Nam, E-mail: knchoi@inu.ac.kr; Rho, Hee Hyuk, E-mail: rdoubleh0902@inu.ac.kr

Wireless sensors without external power supply gained considerable attention due to convenience both in installation and operation. Optical arc detecting sensor equipping with self sustaining power supply using energy harvesting method was investigated. Continuous energy harvesting method was attempted using thermoelectric generator to supply standby power in micro ampere scale and operating power in mA scale. Peltier module with heat-sink was used for high efficiency electricity generator. Optical arc detecting sensor with hybrid filter showed insensitivity to fluorescent and incandescent lamps under simulated distribution panel condition. Signal processing using integrating function showed selective arc discharge detection capability to different arcmore » energy levels, with a resolution below 17 J energy difference, unaffected by bursting arc waveform. The sensor showed possibility for application to arc discharge detecting sensor in power distribution panel. Also experiment with proposed continuous energy harvesting method using thermoelectric power showed possibility as a self sustainable power source of remote sensor.« less

Optical arc sensor using energy harvesting power source

NASA Astrophysics Data System (ADS)

Choi, Kyoo Nam; Rho, Hee Hyuk

2016-06-01

Wireless sensors without external power supply gained considerable attention due to convenience both in installation and operation. Optical arc detecting sensor equipping with self sustaining power supply using energy harvesting method was investigated. Continuous energy harvesting method was attempted using thermoelectric generator to supply standby power in micro ampere scale and operating power in mA scale. Peltier module with heat-sink was used for high efficiency electricity generator. Optical arc detecting sensor with hybrid filter showed insensitivity to fluorescent and incandescent lamps under simulated distribution panel condition. Signal processing using integrating function showed selective arc discharge detection capability to different arc energy levels, with a resolution below 17J energy difference, unaffected by bursting arc waveform. The sensor showed possibility for application to arc discharge detecting sensor in power distribution panel. Also experiment with proposed continuous energy harvesting method using thermoelectric power showed possibility as a self sustainable power source of remote sensor.

Development and Experimental Evaluation of Passive Fuel Cell Thermal Control

NASA Technical Reports Server (NTRS)

Colozza, Anthony J.; Jakupca, Ian J.; Castle, Charles H.; Burke, Kenneth A.

2014-01-01

To provide uniform cooling for a fuel cell stack, a cooling plate concept was evaluated. This concept utilized thin cooling plates to extract heat from the interior of a fuel cell stack and move this heat to a cooling manifold where it can be transferred to an external cooling fluid. The advantages of this cooling approach include a reduced number of ancillary components and the ability to directly utilize an external cooling fluid loop for cooling the fuel cell stack. A number of different types of cooling plates and manifolds were developed. The cooling plates consisted of two main types; a plate based on thermopyrolytic graphite (TPG) and a planar (or flat plate) heat pipe. The plates, along with solid metal control samples, were tested for both thermal and electrical conductivity. To transfer heat from the cooling plates to the cooling fluid, a number of manifold designs utilizing various materials were devised, constructed, and tested. A key aspect of the manifold was that it had to be electrically nonconductive so it would not short out the fuel cell stack during operation. Different manifold and cooling plate configurations were tested in a vacuum chamber to minimize convective heat losses. Cooling plates were placed in the grooves within the manifolds and heated with surface-mounted electric pad heaters. The plate temperature and its thermal distribution were recorded for all tested combinations of manifold cooling flow rates and heater power loads. This testing simulated the performance of the cooling plates and manifold within an operational fuel cell stack. Different types of control valves and control schemes were tested and evaluated based on their ability to maintain a constant temperature of the cooling plates. The control valves regulated the cooling fluid flow through the manifold, thereby controlling the heat flow to the cooling fluid. Through this work, a cooling plate and manifold system was developed that could maintain the cooling plates within a minimal temperature band with negligible thermal gradients over power profiles that would be experienced within an operating fuel cell stack.

Reactivity Studies of Inconel 625 with Sodium, and Lunar Regolith Stimulant

NASA Technical Reports Server (NTRS)

Gillies, Donald; Salvail, Pat; Reid, Bob; Colebaugh, James; Easterling, Greg

2008-01-01

In the event of the need for nuclear power in exploration, high flux heat pipes will be needed for heat transfer from space nuclear reactors to various energy conversion devices, and to safely dissipate excess heat. Successful habitation will necessitate continuous operation of alkali metal filled heat pipes for 10 or-more years in a hostile environment with little maintenance. They must be chemical and creep resistant in the high vacuum of space (lunar), and they must operate reliably in low gravity conditions with intermittent high radiation fluxes. One candidate material for the heat pipe shell, namely Inconel 625, has been tested to determine its compatibility with liquid sodium. Any reactivity could manifest itself as a problem over the long time periods anticipated. In addition, possible reactions with the lunar regolith will take place, as will evaporation of selected elements at the external surfaces of the heat pipes, and so there is a need for extensive long-term testing under simulated lunar conditions.

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.

Automotive Stirling Engine Development Program Mod I Stirling engine development

NASA Technical Reports Server (NTRS)

Simetkosky, M. A.

1983-01-01

The development of the Mod I 4-cylinder automotive Stirling engine is discussed and illustrated with drawings, block diagrams, photographs, and graphs and tables of preliminary test data. The engine and its drive, cold-engine, hot-engine, external-heat, air/fuel, power-control, electronic-control, and auxiliary systems are characterized. Performance results from a total of 1900 h of tests on 4 prototype engines include average maximum efficiency (at 2000 rpm) 34.5 percent and maximum output power 54.4 kW. The modifications introduced in an upgraded version of the Mod I are explained; this engine has maximum efficiency 40.4 percent and maximum power output 69.2 kW.

Investigation of Bose Condensation in Ideal Bose Gas Trapped under Generic Power Law Potential in d Dimension

NASA Astrophysics Data System (ADS)

Mehedi Faruk, Mir; Sazzad Hossain, Md.; Muktadir Rahman, Md.

2016-02-01

The changes in characteristics of Bose condensation of ideal Bose gas due to an external generic power law potential U=\\sumi=1dci\\vert xi/ai\\vertni are studied carefully. Detailed calculation of Kim et al. (J. Phys. Condens. Matter 11 (1999) 10269) yielded the hierarchy of condensation transitions with changing fractional dimensionality. In this manuscript, some theorems regarding specific heat at constant volume CV are presented. Careful examination of these theorems reveal the existence of hidden hierarchy of the condensation transition in trapped systems as well.

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.

Design principles of a simple and safe 200-MW(thermal) nuclear district heating plant

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

Goetzmann, C.; Bittermann, D.; Gobel, A.

Kraftwerk Union AG has almost completed the development of a dedicated 200-MW(thermal) nuclear district heating plant to provide environmentally clean energy at a predictably low cost. The concept can easily be adapted to meet power requirements within the 100- to 500-MW(thermal) range. This technology is the product of the experience gained with large pressurized water reactor and boiling water reactor power plants, with respect to both plant and fuel performance. The major development task is that of achieving sufficiently low capital cost by tailoring components and systems designed for large plants to the specific requirements of district heating. These requirementsmore » are small absolute power, low temperatures and pressures, and modest load following, all of which result in the characteristics that are summarized. A fully integrated primary system with natural circulation permits a very compact reactor building containing all safety-related systems and components. Plant safety is essentially guaranteed by inherent features. The reactor containment is tightly fitted around the reactor pressure vessel in such a way that, in the event of any postulated coolant leak, the core cannot become uncovered, even temporarily. Shutdown is assured by gravity drop of the control rods mounted above the core. Decay heat is removed from the core by means of natural circulation via dedicated intermediate circuits of external aircoolers.« less

The liquid droplet radiator: Status of development

NASA Astrophysics Data System (ADS)

Persson, J.

1991-12-01

The ever greater amounts of power to be dissipated onboard future spacecraft, together with their limited external dimensions, will make it increasingly difficult to use conventional radiator technology without imposing a severe mass penalty. Hunting for lightweight alternatives to current heat rejection systems has become a matter of growing urgency, which explains the great interest that the Liquid Droplet Radiator (LDR) has attracted. Tradeoff analyses indicate that an LDR may be as much as an order of magnitude lighter than a comparable conventional radiator. A literature study examining the progress of the LDR research and some of its possible applications is reviewed. An investigation of the LDR heat rejection capability is presented.

Photovoltaic cell electrical heating system for removing snow on panel including verification.

PubMed

Weiss, Agnes; Weiss, Helmut

2017-11-16

Small photovoltaic plants in private ownership are typically rated at 5 kW (peak). The panels are mounted on roofs at a decline angle of 20° to 45°. In winter time, a dense layer of snow at a width of e.g., 10 cm keeps off solar radiation from the photovoltaic cells for weeks under continental climate conditions. Practically, no energy is produced over the time of snow coverage. Only until outside air temperature has risen high enough for a rather long-time interval to allow partial melting of snow; the snow layer rushes down in an avalanche. Following this proposal, snow removal can be arranged electrically at an extremely positive energy balance in a fast way. A photovoltaic cell is a large junction area diode inside with a threshold voltage of about 0.6 to 0.7 V (depending on temperature). This forward voltage drop created by an externally driven current through the modules can be efficiently used to provide well-distributed heat dissipation at the cell and further on at the glass surface of the whole panel. The adhesion of snow on glass is widely reduced through this heating in case a thin water film can be produced by this external short time heating. Laboratory experiments provided a temperature increase through rated panel current of more than 10 °C within about 10 min. This heating can initiate the avalanche for snow removal on intention as described before provided the clamping effect on snow at the edge of the panel frame is overcome by an additional heating foil. Basics of internal cell heat production, heating thermal effects in time course, thermographic measurements on temperature distribution, power circuit opportunities including battery storage elements and snow-removal under practical conditions are described.

Quasi-adiabatic vacuum-based column housing for very high-pressure liquid chromatography.

PubMed

Gritti, Fabrice; Gilar, Martin; Jarrell, Joseph A

2016-07-22

A prototype vacuum-based (10(-6)Torr) column housing was built to thermally isolate the chromatographic column from the external air environment. The heat transfer mechanism is solely controlled by surface radiation, which was minimized by wrapping the column with low-emissivity aluminum tape. The adiabaticity of the column housing was quantitatively assessed from the measurement of the operational pressure and fluid temperature at the outlet of a 2.1mm×100mm column (sub-2 μm particles). The pressure drop along the column was raised up to 1kbar. The enthalpy balance of the eluent (water, acetonitrile, and one water/acetonitrile mixture, 70/30, v/v) showed that less than 1% of the viscous heat generated by friction of the fluid against the packed bed was lost to the external air environment. Such a vacuum-based column oven minimizes the amplitude of the radial temperature gradients across the column diameter and maximizes its resolving power. Copyright © 2016 Elsevier B.V. All rights reserved.

Post-warm-up muscle temperature maintenance: blood flow contribution and external heating optimisation.

PubMed

Raccuglia, Margherita; Lloyd, Alex; Filingeri, Davide; Faulkner, Steve H; Hodder, Simon; Havenith, George

2016-02-01

Passive muscle heating has been shown to reduce the drop in post-warm-up muscle temperature (Tm) by about 25% over 30 min, with concomitant sprint/power performance improvements. We sought to determine the role of leg blood flow in this cooling and whether optimising the heating procedure would further benefit post-warm-up T m maintenance. Ten male cyclists completed 15-min sprint-based warm-up followed by 30 min recovery. Vastus lateralis Tm (Tmvl) was measured at deep-, mid- and superficial-depths before and after the warm-up, and after the recovery period (POST-REC). During the recovery period, participants wore water-perfused trousers heated to 43 °C (WPT43) with either whole leg heating (WHOLE) or upper leg heating (UPPER), which was compared to heating with electrically heated trousers at 40 °C (ELEC40) and a non-heated control (CON). The blood flow cooling effect on Tmvl was studied comparing one leg with (BF) and without (NBF) blood flow. Warm-up exercise significantly increased Tmvl by ~3 °C at all depths. After the recovery period, BF Tmvl was lower (~0.3 °C) than NBF Tmvl at all measured depths, with no difference between WHOLE versus UPPER. WPT43 reduced the post-warm-up drop in deep-Tmvl (-0.12 °C ± 0.3 °C) compared to ELEC40 (-1.08 ± 0.4 °C) and CON (-1.3 ± 0.3 °C), whereas mid- and superficial-Tmvl even increased by 0.15 ± 0.3 and 1.1 ± 1.1 °C, respectively. Thigh blood flow contributes to the post-warm-up Tmvl decline. Optimising the external heating procedure and increasing heating temperature of only 3 °C successfully maintained and even increased T mvl, demonstrating that heating temperature is the major determinant of post-warm-up Tmvl cooling in this application.

Multifunctional superparamagnetic nanoparticles for enhanced drug transport in cystic fibrosis

NASA Astrophysics Data System (ADS)

Armijo, Leisha M.; Brandt, Yekaterina I.; Rivera, Antonio C.; Cook, Nathaniel C.; Plumley, John B.; Withers, Nathan J.; Kopciuch, Michael; Smolyakov, Gennady A.; Huber, Dale L.; Smyth, Hugh D.; Osinski, Marek

2012-10-01

Iron oxide colloidal nanoparticles (ferrofluids) are investigated for application in the treatment of cystic fibrosis lung infections, the leading cause of mortality in cystic fibrosis patients. We investigate the use of iron oxide nanoparticles to increase the effectiveness of administering antibiotics through aerosol inhalation using two mechanisms: directed particle movement in the presence of an inhomogeneous static external magnetic field and magnetic hyperthermia. Magnetic hyperthermia is an effective method for decreasing the viscosity of the mucus and biofilm, thereby enhancing drug, immune cell, and antibody penetration to the affected area. Iron oxide nanoparticles of various sizes and morphologies were synthesized and tested for specific losses (heating power). Nanoparticles in the superparamagnetic to ferromagnetic size range exhibited excellent heating power. Additionally, iron oxide / zinc selenide core/shell nanoparticles were prepared, in order to enable imaging of the iron oxide nanoparticles. We also report on synthesis and characterization of MnSe/ZnSeS alloyed quantum dots.

Megawatt level electric propulsion perspectives

NASA Technical Reports Server (NTRS)

Jahn, Robert G.; Kelly, Arnold J.

1987-01-01

For long range space missions, deliverable payload fraction is an inverse exponential function of the propellant exhaust velocity or specific impulse of the propulsion system. The exhaust velocity of chemical systems are limited by their combustion chemistry and heat transfer to a few km/s. Nuclear rockets may achieve double this range, but are still heat transfer limited and ponderous to develop. Various electric propulsion systems can achieve exhaust velocities in the 10 km/s range, at considerably lower thrust densities, but require an external electrical power source. A general overview is provided of the currently available electric propulsion systems from the perspective of their characteristics as a terminal load for space nuclear systems. A summary of the available electric propulsion options is shown and generally characterized in the power vs. exhaust velocity plot. There are 3 general classes of electric thruster devices: neutral gas heaters, plasma devices, and space charge limited electrostatic or ion thrusters.

Heat-electrical regeneration way to intensive energy saving in an electric arc furnaces

NASA Astrophysics Data System (ADS)

Kartavtcev, S.; Matveev, S.; Neshporenko, E.

2018-03-01

Energy saving in steel production is of great significance for its large economical scale of 1500 mil t/year and high-energy consumption. Steady trend of last years is an increase of steel production in electric arc furnaces (EAF) with a very high consumption of electricity up to 750 kWh/ton. The intention to reduce so much energy consumption they can reach by many ways. One of such way is a transforming heat energy of liquid steel to electricity and destine it to steel electric arc process. Under certain conditions, it may lead to “zero” consumption of electric power in the process. The development of these conditions leads to the formation of energy-efficient heat schemes, with a minimum electricity consumption from the external network.

Assessment of extreme hydrological conditions in the Bothnian Bay, Baltic Sea, and the impact of the nuclear power plant "Hanhikivi-1" on the local thermal regime

NASA Astrophysics Data System (ADS)

Dvornikov, Anton Y.; Martyanov, Stanislav D.; Ryabchenko, Vladimir A.; Eremina, Tatjana R.; Isaev, Alexey V.; Sein, Dmitry V.

2017-04-01

The results of the study aimed to assess the influence of future nuclear power plant Hanhikivi-1 upon the local thermal conditions in the Bothnian Bay in the Baltic Sea are presented. A number of experiments with different numerical models were also carried out in order to estimate the extreme hydro-meteorological conditions in the area of the construction. The numerical experiments were fulfilled both with analytically specified external forcing and with real external forcing for 2 years: a cold year (2010) and a warm year (2014). The study has shown that the extreme values of sea level and water temperature and the characteristics of wind waves and sea ice in the vicinity of the future nuclear power plant can be significant and sometimes catastrophic. Permanent release of heat into the marine environment from an operating nuclear power plant will lead to a strong increase in temperature and the disappearance of ice cover within a 2 km vicinity of the station. These effects should be taken into account when assessing local climate changes in the future.

Increasing the electric efficiency of a fuel cell system by recirculating the anodic offgas

NASA Astrophysics Data System (ADS)

Heinzel, A.; Roes, J.; Brandt, H.

The University of Duisburg-Essen and the Center for Fuel Cell Technology (ZBT Duisburg GmbH) have developed a compact multi-fuel steam reformer suitable for natural gas, propane and butane. Fuel processor prototypes based on this concept were built up in the power range from 2.5 to 12.5 kW thermal hydrogen power for different applications and different industrial partners. The fuel processor concept contains all the necessary elements, a prereformer step, a primary reformer, water gas shift reactors, a steam generator, internal heat exchangers, in order to achieve an optimised heat integration and an external burner for heat supply as well as a preferential oxidation step (PrOx) as CO purification. One of the built fuel processors is designed to deliver a thermal hydrogen power output of 2.5 kW according to a PEM fuel cell stack providing about 1 kW electrical power and achieves a thermal efficiency of about 75% (LHV basis after PrOx), while the CO content of the product gas is below 20 ppm. This steam reformer has been combined with a 1 kW PEM fuel cell. Recirculating the anodic offgas results in a significant efficiency increase for the fuel processor. The gross efficiency of the combined system was already clearly above 30% during the first tests. Further improvements are currently investigated and developed at the ZBT.

Designing new classes of high-power, high-brightness VECSELs

NASA Astrophysics Data System (ADS)

Moloney, J. V.; Zakharian, A. R.; Hader, J.; Koch, Stephan W.

2005-10-01

Optically-pumped vertical external cavity semiconductor lasers offer the exciting possibility of designing kW-class solid state lasers that provide significant advantages over their doped YAG, thin-disk YAG and fiber counterparts. The basic VECSEL/OPSL (optically-pumped semiconductor laser) structure consists of a very thin (approximately 6 micron thick) active mirror consisting of a DBR high-reflectivity stack followed by a multiple quantum well resonant periodic (RPG) structure. An external mirror (reflectivity typically between 94%-98%) provides conventional optical feedback to the active semiconductor mirror chip. The "cold" cavity needs to be designed to take into account the semiconductor sub-cavity resonance shift with temperature and, importantly, the more rapid shift of the semiconductor material gain peak with temperature. Thermal management proves critical in optimizing the device for serious power scaling. We will describe a closed-loop procedure that begins with a design of the semiconductor active epi structure. This feeds into the sub-cavity optimization, optical and thermal transport within the active structure and thermal transport though the various heat sinking elements. Novel schemes for power scaling beyond current record performances will be discussed.

Design, construction, and measurement of a large solar powered thermoacoustic cooler

NASA Astrophysics Data System (ADS)

Chen, Reh-Lin

2001-07-01

A device based on harnessing concentrated solar power in combination with using thermoacoustic principles has been built, instrumented, and tested. Its acoustic power is generated by solar radiation and is subsequently used to pump heat from external loads. The direct conversion between thermal and mechanical energy without going through any electronic stage makes the mechanism simple. Construction of the solar collector is also rather unsophisticated. It was converted from a 10-ft satellite dish with aluminized Mylar glued on the surface. The thermoacoustic device was mounted on the dish with its engine's hot side positioned near the focus of the parabolic dish, about 1 meter above the center of the dish. A 2-dimensional solar tracking system was built, using two servo motors to position the dish at pre-calculated coordinates. The solar powered thermoacoustic cooler is intended to be used where solar power is abundant and electricity may not be available or reliable. The cooler provides cooling during solar availability. Cooling can be maintained by the latent heat of ice when solar power is unattainable. The device has achieved cooling although compromised by gas leakage and thermal losses and was not able to provide temperatures low enough to freeze water. Improvements of the device are expected through modifications suggested herein.

Design and properties of high-power highly-coherent single-frequency VECSEL emitting in the near- to mid-IR for photonic applications

NASA Astrophysics Data System (ADS)

Garnache, A.; Laurain, A.; Myara, M.; Sellahi, M.; Cerutti, L.; Perez, J. P.; Michon, A.; Beaudoin, G.; Sagnes, I.; Cermak, P.; Romanini, D.

2017-11-01

We demonstrate high power (multiwatt) low noise single frequency operation of tunable compact verical-external- cavity surface-emitting-lasers exhibiting a low divergence high beam quality, of great interest for photonics applications. The quantum-well based lasers are operating in CW at RT at 1μm and 2.3μm exploiting GaAs and Sb technologies. For heat management purpose the VECSEL membranes were bonded on a SiC substrate. Both high power diode pumping (using GaAs commercial diode) at large incidence angle and electrical pumping are developed. The design and physical properties of the coherent wave are presented. We took advantage of thermal lens-based stability to develop a short (0.5-5mm) external cavity without any intracavity filter. We measured a low divergence circular TEM00 beam (M2 = 1.2) close to diffraction limit, with a linear light polarization (> 30 dB). The side mode suppression ratio is > 45 dB. The free running laser linewidth is 37 kHz limited by pump induced thermal fluctuations. Thanks to this high-Q external cavity approach, the frequency noise is low and the dynamics is in the relaxation-oscillation-free regime, exhibiting low intensity noise (< 0.1%), with a cutoff frequency ∽ 41MHz above which the shot noise level is reached. The key parameters limiting the laser power and coherence will be discussed. These design/properties can be extended to other wavelengths.

Numerical prediction of turbulent oscillating flow and associated heat transfer

NASA Technical Reports Server (NTRS)

Koehler, W. J.; Patankar, S. V.; Ibele, W. E.

1991-01-01

A crucial point for further development of engines is the optimization of its heat exchangers which operate under oscillatory flow conditions. It has been found that the most important thermodynamic uncertainties in the Stirling engine designs for space power are in the heat transfer between gas and metal in all engine components and in the pressure drop across the heat exchanger components. So far, performance codes cannot predict the power output of a Stirling engine reasonably enough if used for a wide variety of engines. Thus, there is a strong need for better performance codes. However, a performance code is not concerned with the details of the flow. This information must be provided externally. While analytical relationships exist for laminar oscillating flow, there has been hardly any information about transitional and turbulent oscillating flow, which could be introduced into the performance codes. In 1986, a survey by Seume and Simon revealed that most Stirling engine heat exchangers operate in the transitional and turbulent regime. Consequently, research has since focused on the unresolved issue of transitional and turbulent oscillating flow and heat transfer. Since 1988, the University of Minnesota oscillating flow facility has obtained experimental data about transitional and turbulent oscillating flow. However, since the experiments in this field are extremely difficult, lengthy, and expensive, it is advantageous to numerically simulate the flow and heat transfer accurately from first principles. Work done at the University of Minnesota on the development of such a numerical simulation is summarized.

Influence of thermal deformation in cavity mirrors on beam propagation characteristics of high-power slab lasers

NASA Astrophysics Data System (ADS)

Wang, Zhen; Xiao, Longsheng; Wang, Wei; Wu, Chao; Tang, Xiahui

2018-01-01

Owing to their good diffusion cooling and low sensitivity to misalignment, slab-shape negative-branch unstable-waveguide resonators are widely used for high-power lasers in industry. As the output beam of the resonator is astigmatic, an external beam shaping system is required. However, the transverse dimension of the cavity mirrors in the resonator is large. For a long-time operation, the heating of cavity mirrors can be non-uniform. This results in micro-deformation and a change in the radius of curvature of the cavity mirrors, and leads to an output beam of an offset optical axis of the resonator. It was found that a change in the radius of curvature of 0.1% (1 mm) caused by thermal deformation generates a transverse displacement of 1.65 mm at the spatial filter of the external beam shaping system, and an output power loss of more than 80%. This can potentially burn out the spatial filter. In order to analyze the effect of the offset optical axis of the beam on the external optical path, we analyzed the transverse displacement and rotational misalignments of the spatial filter. For instance, if the transverse displacement was 0.3 mm, the loss in the output power was 9.6% and a sidelobe appeared in the unstable direction. If the angle of rotation was 5°, the loss in the output power was 2%, and the poles were in the direction of the waveguide. Based on these results, by adjusting the bending mirror, the deviation angle of the output beam of the resonator cavity was corrected, in order to obtain maximum output power and optimal beam quality. Finally, the propagation characteristics of the corrected output beam were analyzed.

Thermal coupling potential of Solid Oxide Fuel Cells with metal hydride tanks: Thermodynamic and design considerations towards integrated systems

NASA Astrophysics Data System (ADS)

Yiotis, Andreas G.; Kainourgiakis, Michael E.; Kosmidis, Lefteris I.; Charalambopoulou, Georgia C.; Stubos, Athanassios K.

2014-12-01

We study the thermal coupling potential between a high temperature metal hydride (MH) tank and a Solid Oxide Fuel Cell (SOFC) aiming towards the design of an efficient integrated system, where the thermal power produced during normal SOFC operation is redirected towards the MH tank in order to maintain H2 desorption without the use of external heating sources. Based on principles of thermodynamics, we calculate the energy balance in the SOFC/MH system and derive analytical expressions for both the thermal power produced during SOFC operation and the corresponding thermal power required for H2 desorption, as a function of the operating temperature, efficiency and fuel utilization ratio in the SOFC, and the MH enthalpy of desorption in the tank. Based on these calculations, we propose an integrated SOFC/MH design where heat is transferred primarily by radiation to the tank in order to maintain steady-state desorption conditions. We develop a mathematical model for this particular design that accounts for heat/mass transfer and desorption kinetics in the tank, and solve for the dynamics of the system assuming MgH2 as a storage material. Our results focus primarily on tank operating conditions, such as pressure, temperature and H2 saturation profiles vs operation time.

Scale Resistant Heat Exchanger for Low Temperature Geothermal Binary Cycle Power Plant

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

Hays, Lance G.

2014-11-18

Phase 1 of the investigation of improvements to low temperature geothermal power systems was completed. The improvements considered were reduction of scaling in heat exchangers and a hermetic turbine generator (eliminating seals, seal system, gearbox, and lube oil system). A scaling test system with several experiments was designed and operated at Coso geothermal resource with brine having a high scaling potential. Several methods were investigated at the brine temperature of 235 ºF. One method, circulation of abradable balls through the brine passages, was found to substantially reduce scale deposits. The test heat exchanger was operated with brine outlet temperatures asmore » low as 125 ºF, which enables increased heat input available to power conversion systems. For advanced low temperature cycles, such as the Variable Phase Cycle (VPC) or Kalina Cycle, the lower brine temperature will result in a 20-30% increase in power production from low temperature resources. A preliminary design of an abradable ball system (ABS) was done for the heat exchanger of the 1 megawatt VPC system at Coso resource. The ABS will be installed and demonstrated in Phase 2 of this project, increasing the power production above that possible with the present 175 ºF brine outlet limit. A hermetic turbine generator (TGH) was designed and manufacturing drawings produced. This unit will use the working fluid (R134a) to lubricate the bearings and cool the generator. The 200 kW turbine directly drives the generator, eliminating a gearbox and lube oil system. Elimination of external seals eliminates the potential of leakage of the refrigerant or hydrocarbon working fluids, resulting in environmental improvement. A similar design has been demonstrated by Energent in an ORC waste heat recovery system. The existing VPC power plant at Coso was modified to enable the “piggyback” demonstration of the TGH. The existing heat exchanger, pumps, and condenser will be operated to provide the required process conditions for the TGH demonstration. Operation of the TGH with and without the ABS system will demonstrate an increase in geothermal resource productivity for the VPC from 1 MW/(million lb) of brine to 1.75 MW/(million lb) of brine, a 75% increase.« less

Application of turbulence modeling to predict surface heat transfer in stagnation flow region of circular cylinder

NASA Technical Reports Server (NTRS)

Wang, Chi R.; Yeh, Frederick C.

1987-01-01

A theoretical analysis and numerical calculations for the turbulent flow field and for the effect of free-stream turbulence on the surface heat transfer rate of a stagnation flow are presented. The emphasis is on the modeling of turbulence and its augmentation of surface heat transfer rate. The flow field considered is the region near the forward stagnation point of a circular cylinder in a uniform turbulent mean flow. The free stream is steady and incompressible with a Reynolds number of the order of 10 to the 5th power and turbulence intensity of less than 5 percent. For this analysis, the flow field is divided into three regions: (1) a uniform free-stream region where the turbulence is homogeneous and isotropic; (2) an external viscid flow region where the turbulence is distorted by the variation of the mean flow velocity; and, (3) an anisotropic turbulent boundary layer region over the cylinder surface. The turbulence modeling techniques used are the kappa-epsilon two-equation model in the external flow region and the time-averaged turbulence transport equation in the boundary layer region. The turbulence double correlations, the mean velocity, and the mean temperature within the boundary layer are solved numerically from the transport equations. The surface heat transfer rate is calculated as functions of the free-stream turbulence longitudinal microlength scale, the turbulence intensity, and the Reynolds number.

Control of thermal therapies with moving power deposition field.

PubMed

Arora, Dhiraj; Minor, Mark A; Skliar, Mikhail; Roemer, Robert B

2006-03-07

A thermal therapy feedback control approach to control thermal dose using a moving power deposition field is developed and evaluated using simulations. A normal tissue safety objective is incorporated in the controller design by imposing constraints on temperature elevations at selected normal tissue locations. The proposed control technique consists of two stages. The first stage uses a model-based sliding mode controller that dynamically generates an 'ideal' power deposition profile which is generally unrealizable with available heating modalities. Subsequently, in order to approximately realize this spatially distributed idealized power deposition, a constrained quadratic optimizer is implemented to compute intensities and dwell times for a set of pre-selected power deposition fields created by a scanned focused transducer. The dwell times for various power deposition profiles are dynamically generated online as opposed to the commonly employed a priori-decided heating strategies. Dynamic intensity and trajectory generation safeguards the treatment outcome against modelling uncertainties and unknown disturbances. The controller is designed to enforce simultaneous activation of multiple normal tissue temperature constraints by rapidly switching between various power deposition profiles. The hypothesis behind the controller design is that the simultaneous activation of multiple constraints substantially reduces treatment time without compromising normal tissue safety. The controller performance and robustness with respect to parameter uncertainties is evaluated using simulations. The results demonstrate that the proposed controller can successfully deliver the desired thermal dose to the target while maintaining the temperatures at the user-specified normal tissue locations at or below the maximum allowable values. Although demonstrated for the case of a scanned focused ultrasound transducer, the developed approach can be extended to other heating modalities with moving deposition fields, such as external and interstitial ultrasound phased arrays, multiple radiofrequency needle applicators and microwave antennae.

Performance of the Mechanically Pumped Fluid Loop Rover Heat Rejection System Used for Thermal Control of the Mars Science Laboratory Curiosity Rover on the Surface of Mars

NASA Technical Reports Server (NTRS)

Bhandari, Pradeep; Birur, Gajanana; Bame, David; Mastropietro, A. J.; Miller, Jennifer; Karlmann, Paul; Liu, Yuanming; Anderson, Kevin

2013-01-01

The challenging range of landing sites for which the Mars Science Laboratory Rover was designed, required a rover thermal management system that is capable of keeping temperatures controlled across a wide variety of environmental conditions. On the Martian surface where temperatures can be as cold as -123 C and as warm as 38 C, the Rover relies upon a Mechanically Pumped Fluid Loop (MPFL) Rover Heat Rejection System (RHRS) and external radiators to maintain the temperature of sensitive electronics and science instruments within a -40 C to +50 C range. The RHRS harnesses some of the waste heat generated from the Rover power source, known as the Multi Mission Radioisotope Thermoelectric Generator (MMRTG), for use as survival heat for the rover during cold conditions. The MMRTG produces 110 Watts of electrical power while generating waste heat equivalent to approximately 2000 Watts. Heat exchanger plates (hot plates) positioned close to the MMRTG pick up this survival heat from it by radiative heat transfer and supply it to the rover. This design is the first instance of use of a RHRS for thermal control of a rover or lander on the surface of a planet. After an extremely successful landing on Mars (August 5), the rover and the RHRS have performed flawlessly for close to an earth year (half the nominal mission life). This paper will share the performance of the RHRS on the Martian surface as well as compare it to its predictions.

Internal cooling of a lithium-ion battery using electrolyte as coolant through microchannels embedded inside the electrodes

NASA Astrophysics Data System (ADS)

Mohammadian, Shahabeddin K.; He, Ya-Ling; Zhang, Yuwen

2015-10-01

Two and three dimensional transient thermal analysis of a prismatic Li-ion cell has been carried out to compare internal and external cooling methods for thermal management of Lithium Ion (Li-ion) battery packs. Water and liquid electrolyte have been utilized as coolants for external and internal cooling, respectively. The effects of the methods on decreasing the temperature inside the battery and also temperature uniformity were investigated. The results showed that at the same pumping power, using internal cooling not only decreases the bulk temperature inside the battery more than external cooling, but also decreases the standard deviation of the temperature field inside the battery significantly. Finally, using internal cooling decreases the intersection angle between the velocity vector and the temperature gradient which according to field synergy principle (FSP) causes to increase the convection heat transfer.

Low bandgap mid-infrared thermophotovoltaic arrays based on InAs

NASA Astrophysics Data System (ADS)

Krier, A.; Yin, M.; Marshall, A. R. J.; Kesaria, M.; Krier, S. E.; McDougall, S.; Meredith, W.; Johnson, A. D.; Inskip, J.; Scholes, A.

2015-11-01

We demonstrate the first low bandgap thermophotovoltaic (TPV) arrays capable of operating with heat sources at temperatures as low as 345 °C, which is the lowest ever reported. The individual array elements are based on narrow band gap InAs/InAs0.61Sb0.13P0.26 photodiode structures. External power conversion efficiency was measured to be ∼3% from a single element at room temperature, using a black body at 950 °C. Both 25-element and 65-element arrays were fabricated and exhibited a TPV response at different source temperatures in the range 345-950 °C suitable for electricity generation from waste heat and other applications.

Spacecraft active thermal control subsystem design and operation considerations

NASA Technical Reports Server (NTRS)

Sadunas, J. A.; Lehtinen, A. M.; Nguyen, H. T.; Parish, R.

1986-01-01

Future spacecraft missions will be characterized by high electrical power requiring active thermal control subsystems for acquisition, transport, and rejection of waste heat. These systems will be designed to operate with minimum maintenance for up to 10 years, with widely varying externally-imposed environments, as well as the spacecraft waste heat rejection loads. This paper presents the design considerations and idealized performance analysis of a typical thermal control subsystem with emphasis on the temperature control aspects during off-design operation. The selected thermal management subsystem is a cooling loop for a 75-kWe fuel cell subsystem, consisting of a fuel cell heat exchanger, thermal storage, pumps, and radiator. Both pumped-liquid transport and two-phase (liquid/vapor) transport options are presented with examination of similarities and differences of the control requirements for these representative thermal control options.

DEMO port plug design and integration studies

NASA Astrophysics Data System (ADS)

Grossetti, G.; Boccaccini, L. V.; Cismondi, F.; Del Nevo, A.; Fischer, U.; Franke, T.; Granucci, G.; Hernández, F.; Mozzillo, R.; Strauß, D.; Tran, M. Q.; Vaccaro, A.; Villari, R.

2017-11-01

The EUROfusion Consortium established in 2014 and composed by European Fusion Laboratories, and in particular the Power Plant Physics and Technology department aims to develop a conceptual design for the Fusion DEMOnstration Power Plant, DEMO. With respect to present experimental machines and ITER, the main goals of DEMO are to produce electricity continuously for a period of about 2 h, with a net electrical power output of a few hundreds of MW, and to allow tritium self-sufficient breeding with an adequately high margin in order to guarantee its planned operational schedule, including all planned maintenance intervals. This will eliminate the need to import tritium fuel from external sources during operations. In order to achieve these goals, extensive engineering efforts as well as physics studies are required to develop a design that can ensure a high level of plant reliability and availability. In particular, interfaces between systems must be addressed at a very early phase of the project, in order to proceed consistently. In this paper we present a preliminary design and integration study, based on physics assessments for the EU DEMO1 Baseline 2015 with an aspect ratio of 3.1 and 18 toroidal field coils, for the DEMO port plugs. These aim to host systems like electron cyclotron heating launchers currently developed within the Work Package Heating and Current Drive that need an external radial access to the plasma and through in-vessel systems like the breeder blanket. A similar approach shown here could be in principle followed by other systems, e.g. other heating and current drive systems or diagnostics. The work addresses the interfaces between the port plug and the blanket considering the helium-cooled pebble bed and the water cooled lithium lead which are two of four breeding blanket concepts under investigation in Europe within the Power Plant Physics and Technology Programme: the required openings will be evaluated in terms of their impact onto the blanket segments thermo-mechanical and nuclear design considering mechanical integration aspects but also their impact on tritium breeding ratio. Since DEMO is still in a pre-conceptual phase, the same methodology is applicable to the other two blanket concepts, as well.

ADX: a high field, high power density, advanced divertor and RF tokamak

NASA Astrophysics Data System (ADS)

LaBombard, B.; Marmar, E.; Irby, J.; Terry, J. L.; Vieira, R.; Wallace, G.; Whyte, D. G.; Wolfe, S.; Wukitch, S.; Baek, S.; Beck, W.; Bonoli, P.; Brunner, D.; Doody, J.; Ellis, R.; Ernst, D.; Fiore, C.; Freidberg, J. P.; Golfinopoulos, T.; Granetz, R.; Greenwald, M.; Hartwig, Z. S.; Hubbard, A.; Hughes, J. W.; Hutchinson, I. H.; Kessel, C.; Kotschenreuther, M.; Leccacorvi, R.; Lin, Y.; Lipschultz, B.; Mahajan, S.; Minervini, J.; Mumgaard, R.; Nygren, R.; Parker, R.; Poli, F.; Porkolab, M.; Reinke, M. L.; Rice, J.; Rognlien, T.; Rowan, W.; Shiraiwa, S.; Terry, D.; Theiler, C.; Titus, P.; Umansky, M.; Valanju, P.; Walk, J.; White, A.; Wilson, J. R.; Wright, G.; Zweben, S. J.

2015-05-01

The MIT Plasma Science and Fusion Center and collaborators are proposing a high-performance Advanced Divertor and RF tokamak eXperiment (ADX)—a tokamak specifically designed to address critical gaps in the world fusion research programme on the pathway to next-step devices: fusion nuclear science facility (FNSF), fusion pilot plant (FPP) and/or demonstration power plant (DEMO). This high-field (⩾6.5 T, 1.5 MA), high power density facility (P/S ˜ 1.5 MW m-2) will test innovative divertor ideas, including an ‘X-point target divertor’ concept, at the required performance parameters—reactor-level boundary plasma pressures, magnetic field strengths and parallel heat flux densities entering into the divertor region—while simultaneously producing high-performance core plasma conditions that are prototypical of a reactor: equilibrated and strongly coupled electrons and ions, regimes with low or no torque, and no fuelling from external heating and current drive systems. Equally important, the experimental platform will test innovative concepts for lower hybrid current drive and ion cyclotron range of frequency actuators with the unprecedented ability to deploy launch structures both on the low-magnetic-field side and the high-magnetic-field side—the latter being a location where energetic plasma-material interactions can be controlled and favourable RF wave physics leads to efficient current drive, current profile control, heating and flow drive. This triple combination—advanced divertors, advanced RF actuators, reactor-prototypical core plasma conditions—will enable ADX to explore enhanced core confinement physics, such as made possible by reversed central shear, using only the types of external drive systems that are considered viable for a fusion power plant. Such an integrated demonstration of high-performance core-divertor operation with steady-state sustainment would pave the way towards an attractive pilot plant, as envisioned in the ARC concept (affordable, robust, compact) (Sorbom et al 2015 Fusion Eng. Des. submitted (arXiv:1409.3540)) that makes use of high-temperature superconductor technology—a high-field (9.25 T) tokamak the size of the Joint European Torus that produces 270 MW of net electricity.

The Design, Construction, and Experimental Evaluation of a Compact Thermoacoustic-Stirling Engine Generator for Use in a micro-CHP Appliance

NASA Astrophysics Data System (ADS)

Wilcox, Douglas A., Jr.

Micro combined heat and power or micro-CHP is the simultaneous generation of useful heat and electricity on a residential scale. The heat and electricity are produced at the point of use, avoiding the distribution losses associated with a centralized power plant. These appliances combine a conventional gas-fired condensing boiler with an electric power module capable of generating electricity from the heat of combustion. Currently, the leading power modules for micro-CHP appliances are free-piston Stirling engines (FPSEs) which can generate 1050 watts of electricity at a thermal-to-electric efficiency of 26%.[1] These external combustion engines have been under development for the last 25 years, with FPSE micro-CHP appliances only recently being introduced to the commercial market. Publications by developers assert unlimited service life and high efficiency, with low noise and emissions; but despite these claims, the actual reliability and cost of manufacturing has prevented their successful mass-market adoption. A Thermoacoustic-Stirling Engine Generator or TaSEG is one possible alternative to FPSE's. A TaSEG uses a thermoacoustic engine, or acoustic heat engine, which can efficiently convert high temperature heat into acoustic power while maintaining a simple design with fewer moving parts than traditional FPSE's. This simpler engine is coupled to an electrodynamic alternator capable of converting acoustic power into electricity. This thesis outlines the design, construction, and experimental evaluation of a TaSEG which is appropriate for integration with a gas burner inside of a residential micro- CHP appliance. The design methodology is discussed, focusing on how changes in the geometry affected the predicted performance. Details of its construction are given and the performance of the TaSEG is then outlined. The TaSEG can deliver 132 watts of electrical output power to an electric load with an overall measured thermal-to-electric (first law) efficiency of eta T-E=8.32%, corresponding to 14% of Carnot etac. The volumetric power density of this TaSEG is 8.9 kW/m3. While the demonstrated overall efficiency is modest (for reasons that are largely understood), this TaSEG has moved the technology away from laboratory prototypes toward a commercially viable power module having a design configuration suitable for implementation in a micro-CHP appliance. Based on the TaSEG's measured experimental performance results, recommendations for future work that might improve the overall efficiency of the TaSEG are also presented.

Energy distributions of an ion in a radio-frequency trap immersed in a buffer gas under the influence of additional external forces

NASA Astrophysics Data System (ADS)

Rouse, I.; Willitsch, S.

2018-04-01

An ion held in a radio-frequency trap interacting with a uniform buffer gas of neutral atoms develops a steady-state energy distribution characterized by a power-law tail at high energies instead of the exponential decay characteristic of thermal equilibrium. We have previously shown that the Tsallis statistics frequently used as an empirical model for this distribution is a good approximation when the ion is heated due to a combination of micromotion interruption and exchange of kinetic energy with the buffer gas [Rouse and Willitsch, Phys. Rev. Lett. 118, 143401 (2017), 10.1103/PhysRevLett.118.143401]. Here, we extend our treatment to include the heating due to additional motion of the ion caused by external forces, including the "excess micromotion" induced by uniform electric fields and rf phase offsets. We show that this also leads to a Tsallis distribution with a potentially different power-law exponent from that observed in the absence of this additional forced motion, with the difference increasing as the ratio of the mass of the neutral atoms to that of the ion decreases. Our results indicate that unless the excess micromotion is minimized to a very high degree, then even a system with very light neutrals and a heavy ion does not exhibit a thermal distribution.

Thermal analyses of power subsystem components

NASA Technical Reports Server (NTRS)

Morehouse, Jeffrey H.

1990-01-01

The hiatus in the Space Shuttle (Orbiter) program provided time for an in-depth examination of all the subsystems and their past performance. Specifically, problems with reliability and/or operating limits were and continue to be of major engineering concern. The Orbiter Auxiliary Power Unit (APU) currently operates with electric resistance line heaters which are controlled with thermostats. A design option simplification of this heater subsystem is being considered which would use self-regulating heaters. A determination of the properties and thermal operating characteristics of these self-regulating heaters was needed. The Orbiter fuel cells are cooled with a freon loop. During a loss of external heat exchanger coolant flow, the single pump circulating the freon is to be left running. It was unknown what temperature and flow rate transient conditions of the freon would provide the required fuel cell cooling and for how long. The overall objective was the development of the thermal characterization and subsequent analysis of both the proposed self-regulating APU heater and the fuel cell coolant loop subsystem. The specific objective of the APU subsystem effort was to determine the feasibility of replacing the current heater and thermostat arrangement with a self-regulating heater. The specific objective of the fuel cell coolant subsystem work was to determine the tranient coolant temperature and associated flow rates during a loss-of-external heat exchanger flow.

WATER BOILER REACTOR

DOEpatents

King, L.D.P.

1960-11-22

As its name implies, this reactor utilizes an aqueous solution of a fissionable element salt, and is also conventional in that it contains a heat exchanger cooling coil immersed in the fuel. Its novelty lies in the utilization of a cylindrical reactor vessel to provide a critical region having a large and constant interface with a supernatant vapor region, and the use of a hollow sleeve coolant member suspended from the cover assembly in coaxial relation with the reactor vessel. Cool water is circulated inside this hollow coolant member, and a gap between its outer wall and the reactor vessel is used to carry off radiolytic gases for recombination in an external catalyst chamber. The central passage of the coolant member defines a reflux condenser passage into which the externally recombined gases are returned and condensed. The large and constant interface between fuel solution and vapor region prevents the formation of large bubbles and minimizes the amount of fuel salt carried off by water vapor, thus making possible higher flux densities, specific powers and power densities.

Plasma-catalyzed fuel reformer

DOEpatents

Hartvigsen, Joseph J.; Elangovan, S.; Czernichowski, Piotr; Hollist, Michele

2013-06-11

A reformer is disclosed that includes a plasma zone to receive a pre-heated mixture of reactants and ionize the reactants by applying an electrical potential thereto. A first thermally conductive surface surrounds the plasma zone and is configured to transfer heat from an external heat source into the plasma zone. The reformer further includes a reaction zone to chemically transform the ionized reactants into synthesis gas comprising hydrogen and carbon monoxide. A second thermally conductive surface surrounds the reaction zone and is configured to transfer heat from the external heat source into the reaction zone. The first thermally conductive surface and second thermally conductive surface are both directly exposed to the external heat source. A corresponding method and system are also disclosed and claimed herein.

Safety considerations for wireless delivery of continuous power to implanted medical devices.

PubMed

Lucke, Lori; Bluvshtein, Vlad

2014-01-01

Wireless power systems for use with implants are referred to as transcutaneous energy transmission systems (TETS) and consist of an implanted secondary coil and an external primary coil along with supporting electronics. A TETS system could be used to power ventricular assist systems and eliminate driveline infections. There are both direct and indirect safety concerns that must be addressed when continuously transferring power through the skin. Direct safety concerns include thermal tissue damage caused by exposure to the electromagnetic fields, coil heating effects, and potential unwanted nerve stimulation. Indirect concerns are those caused by potential interference of the TETS system with other implanted devices. Wireless power systems are trending towards higher frequency operation. Understanding the limits for safe operation of a TETS system across a range of frequencies is important. A low frequency and a high frequency implementation are simulated to demonstrate the impact of this trend for a VAD application.

Laser surface modification of medical grade alloys for reduced heating in a magnetic resonance imaging environment

NASA Astrophysics Data System (ADS)

Benafan, O.; Chen, S.-Y.; Kar, A.; Vaidyanathan, R.

2015-12-01

Nanoscale surface modification of medical grade metallic alloys was conducted using a neodymium-doped yttrium aluminum garnet laser-based dopant diffusion technique. The objective of this approach was to minimize the induction heating by reducing the absorbed radio frequency field. Such an approach is advantageous in that the dopant is diffused into the alloy and is not susceptible to detachment or spallation as would an externally applied coating, and is expected to not deteriorate the mechanical and electrical properties of the base alloy or device. Experiments were conducted using a controlled environment laser system with the ability to control laser properties (i.e., laser power, spot size, and irradiation time) and dopant characteristics (i.e., temperature, concentration, and pressure). The reflective and transmissive properties of both the doped and untreated samples were measured in a radio frequency (63.86 MHz) magnetic field using a system comprising a high power signal generator, a localized magnetic field source and sensor, and a signal analyzer. The results indicate an increase in the reflectivity of the laser-treated samples compared to untreated samples. The effect of reflectivity on the heating of the alloys is investigated through a mathematical model incorporating Maxwell's equations and heat conduction.

Closing the gap between socioeconomic and financial implications of residential and community level hydrogen-based energy systems: Incentives needed for a bridge to the future

NASA Astrophysics Data System (ADS)

Verduzco, Laura E.

The use of hydrogen as an energy carrier has the potential to decrease the amount of pollutants emitted to the atmosphere, significantly reduce our dependence on imported oil and resolve geopolitical issues related to energy consumption. The current status of hydrogen technology makes it prohibitive and financially risky for most investors to commit the money required for large-scale hydrogen production. Therefore, alternative strategies such as small and medium-scale hydrogen applications should be implemented during the early stages of the transition to the hydrogen economy in order to test potential markets and technology readiness. While many analysis tools have been built to estimate the requirements of the transition to a hydrogen economy, few have focused on small and medium-scale hydrogen production and none has paired financial with socioeconomic costs at the residential level. The computer-based tool (H2POWER) presented in this study calculates the capacity, cost and socioeconomic impact of the systems needed to meet the energy demands of a home or a community using home and neighborhood refueling units, which are systems that can provide electricity and heat to meet the energy demands of either (1) a home and automobile or (2) a cluster of homes and a number of automobiles. The financial costs of the production, processing and delivery sub-systems that conform the refueling units are calculated using cost data of existing technology and normalizing them to calculate capital and net present cost. The monetary value of the externalities (socioeconomic analysis) caused by each system is calculated by H2POWER through a statistical analysis of the cost associated to various externalities. Additionally, H2POWER calculates the financial impact of different penalties and incentives (such as net metering, low interest loans, fuel taxes, and emission penalties) on the cost of the system from the point of view of a developer and a homeowner. In order to assess the benefits and costs of hydrogen-based alternatives, H2POWER compares the financial and socioeconomic costs of home and neighborhood refueling units to a baseline of "conventional" sources of residential electricity, space heat, water heat, and vehicle fuel. The model can also calculate the "gap" between the financial cost of the technology and the environmental cost of the externalities that are generated using conventional energy sources. H2POWER is a flexible, user-friendly tool that allows the user to specify different production pathways, supplemental power sources (renewable and non-renewable), component characteristics, electricity mixes, and other analysis parameters in order to customize the results to specific projects. The model has also built-in default values for each of the input fields based on national averages, standard technology specifications and input from experts.

Self-contained small utility system

DOEpatents

Labinov, Solomon D.; Sand, James R.

1995-01-01

A method and apparatus is disclosed to provide a fuel efficient source of readily converted energy to an isolated or remote energy consumption facility. External heat from any of a large variety of sources is converted to an electrical, mechanical, heat or cooling form of energy. A polyatomic working fluid energized by external heat sources is dissociated to a higher gaseous energy state for expansion through a turbine prime mover. The working fluid discharge from the turbine prime mover is routed to a recouperative heat exchanger for exothermic recombination reaction heat transfer to working fluid discharged from the compressor segment of the thermodynaic cycle discharge. The heated compressor discharge fluid is thereafter further heated by the external heat source to the initial higher energy state. Under the pressure at the turbine outlet, the working fluid goes out from a recouperative heat exchanger to a superheated vapor heat exchanger where it is cooled by ambient medium down to an initial temperature of condensation. Thereafter, the working fluid is condensed to a complete liquid state in a condenser cooled by an external medium. This liquid is expanded isenthalpically down to the lowest pressure of the cycle. Under this pressure, the working fluid is evaporated to the superheated vapor state of the inlet of a compressor.

24 CFR 3280.702 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-04-01

... a comfort cooling appliance where the condenser section is placed external to the manufactured home... a comfort cooling appliance where the condenser section is placed external to the manufactured home... case of a heat pump) heat air for use in comfort cooling (or heating) the living space. Air...

Heat regenerative external combustion engine

NASA Astrophysics Data System (ADS)

Duva, Anthony W.

1993-03-01

It is an object of the invention to provide an external combustion expander-type engine having improved efficiency. It is another object of the invention to provide an external combustion engine in which afterburning in the exhaust channel is substantially prevented. Yet another object of the invention is to provide an external combustion engine which is less noisy than an external combustion engine of conventional design. These and other objects of the invention will become more apparent from the following description. The above objects of the invention are realized by providing a heat regenerative external combustion engine. The heat regenerative external combustion engine of the invention comprises a combustion chamber for combusting a monopropellant fuel in order to form an energized gas. The energized gas is then passed through a rotary valve to a cylinder having a reciprocating piston disposed therein. The gas is spent in moving the piston, thereby driving a drive shaft.

Two coupled, driven Ising spin systems working as an engine.

PubMed

Basu, Debarshi; Nandi, Joydip; Jayannavar, A M; Marathe, Rahul

2017-05-01

Miniaturized heat engines constitute a fascinating field of current research. Many theoretical and experimental studies are being conducted that involve colloidal particles in harmonic traps as well as bacterial baths acting like thermal baths. These systems are micron-sized and are subjected to large thermal fluctuations. Hence, for these systems average thermodynamic quantities, such as work done, heat exchanged, and efficiency, lose meaning unless otherwise supported by their full probability distributions. Earlier studies on microengines are concerned with applying Carnot or Stirling engine protocols to miniaturized systems, where system undergoes typical two isothermal and two adiabatic changes. Unlike these models we study a prototype system of two classical Ising spins driven by time-dependent, phase-different, external magnetic fields. These spins are simultaneously in contact with two heat reservoirs at different temperatures for the full duration of the driving protocol. Performance of the model as an engine or a refrigerator depends only on a single parameter, namely the phase between two external drivings. We study this system in terms of fluctuations in efficiency and coefficient of performance (COP). We find full distributions of these quantities numerically and study the tails of these distributions. We also study reliability of the engine. We find the fluctuations dominate mean values of efficiency and COP, and their probability distributions are broad with power law tails.

Two coupled, driven Ising spin systems working as an engine

NASA Astrophysics Data System (ADS)

Basu, Debarshi; Nandi, Joydip; Jayannavar, A. M.; Marathe, Rahul

2017-05-01

Miniaturized heat engines constitute a fascinating field of current research. Many theoretical and experimental studies are being conducted that involve colloidal particles in harmonic traps as well as bacterial baths acting like thermal baths. These systems are micron-sized and are subjected to large thermal fluctuations. Hence, for these systems average thermodynamic quantities, such as work done, heat exchanged, and efficiency, lose meaning unless otherwise supported by their full probability distributions. Earlier studies on microengines are concerned with applying Carnot or Stirling engine protocols to miniaturized systems, where system undergoes typical two isothermal and two adiabatic changes. Unlike these models we study a prototype system of two classical Ising spins driven by time-dependent, phase-different, external magnetic fields. These spins are simultaneously in contact with two heat reservoirs at different temperatures for the full duration of the driving protocol. Performance of the model as an engine or a refrigerator depends only on a single parameter, namely the phase between two external drivings. We study this system in terms of fluctuations in efficiency and coefficient of performance (COP). We find full distributions of these quantities numerically and study the tails of these distributions. We also study reliability of the engine. We find the fluctuations dominate mean values of efficiency and COP, and their probability distributions are broad with power law tails.

GRIZZLY Model of Multi-Reactive Species Diffusion, Moisture/Heat Transfer and Alkali-Silica Reaction for Simulating Concrete Aging and Degradation

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

Huang, Hai; Spencer, Benjamin W.; Cai, Guowei

Concrete is widely used in the construction of nuclear facilities because of its structural strength and its ability to shield radiation. The use of concrete in nuclear power plants for containment and shielding of radiation and radioactive materials has made its performance crucial for the safe operation of the facility. As such, when life extension is considered for nuclear power plants, it is critical to have accurate and reliable predictive tools to address concerns related to various aging processes of concrete structures and the capacity of structures subjected to age-related degradation. The goal of this report is to document themore » progress of the development and implementation of a fully coupled thermo-hydro-mechanical-chemical model in GRIZZLY code with the ultimate goal to reliably simulate and predict long-term performance and response of aged NPP concrete structures subjected to a number of aging mechanisms including external chemical attacks and volume-changing chemical reactions within concrete structures induced by alkali-silica reactions and long-term exposure to irradiation. Based on a number of survey reports of concrete aging mechanisms relevant to nuclear power plants and recommendations from researchers in concrete community, we’ve implemented three modules during FY15 in GRIZZLY code, (1) multi-species reactive diffusion model within cement materials; (2) coupled moisture and heat transfer model in concrete; and (3) anisotropic, stress-dependent, alkali-silica reaction induced swelling model. The multi-species reactive diffusion model was implemented with the objective to model aging of concrete structures subjected to aggressive external chemical attacks (e.g., chloride attack, sulfate attack, etc.). It considers multiple processes relevant to external chemical attacks such as diffusion of ions in aqueous phase within pore spaces, equilibrium chemical speciation reactions and kinetic mineral dissolution/precipitation. The moisture/heat transfer module was implemented to simulate long-term spatial and temporal evolutions of the moisture and temperature fields within concrete structures at both room and elevated temperatures. The ASR swelling model implemented in GRIZZLY code can simulate anisotropic expansions of ASR gel under either uniaxial, biaxial and triaxial stress states, and can be run simultaneously with the moisture/heat transfer model and coupled with various elastic/inelastic solid mechanics models that were implemented in GRIZZLY code previously. This report provides detailed descriptions of the governing equations, constitutive equations and numerical algorithms of the three modules implemented in GRIZZLY during FY15, simulation results of example problems and model validation results by comparing simulations with available experimental data reported in the literature. The close match between the experiments and simulations clearly demonstrate the potential of GRIZZLY code for reliable evaluation and prediction of long-term performance and response of aged concrete structures in nuclear power plants.« less

Thermal design, analysis and comparison on three concepts of space solar power satellite

NASA Astrophysics Data System (ADS)

Yang, Chen; Hou, Xinbin; Wang, Li

2017-08-01

Space solar power satellites (SSPS) have been widely studied as systems for collecting solar energy in space and transmitting it wirelessly to earth. A previously designed planar SSPS concept collects solar power in two huge arrays and then transmits it through one side of the power-conduction joint to the antenna. However, the system's one group of power-conduction joints may induce a single point of failure. As an SSPS concept, the module symmetrical concentrator (MSC) architecture has many advantages. This architecture can help avoid the need for a large, potentially failure-prone conductive rotating joint and limit wiring mass. However, the thermal control system has severely restricted the rapid development of MSC, especially in the sandwich module. Because of the synchronous existence of five suns concentration and solar external heat flux, the sandwich module will have a very high temperature, which will surpass the permissible temperature of the solar cells. Recently, an alternate multi-rotary joints (MR) SSPS concept was designed by the China Academy of Space Technology (CAST). This system has multiple joints to avoid the problem of a single point of failure. Meanwhile, this concept has another advantage for reducing the high power and heat removal in joints. It is well known to us that, because of the huge external flux in SSPS, the thermal management sub-system is an important component that cannot be neglected. Based on the three SSPS concepts, this study investigated the thermal design and analysis of a 1-km, gigawatt-level transmitting antenna in SSPS. This study compares the thermal management sub-systems of power-conduction joints in planar and MR SSPS. Moreover, the study considers three classic thermal control architectures of the MSC's sandwich module: tile, step, and separation. The study also presents an elaborate parameter design, analysis and discussion of step architecture. Finally, the results show the thermal characteristics of each SSPS concept, and the three concepts are compared. The design layouts, analysis results and parameter discussions of the thermal management sub-system proposed in this study can help inform future SSPS thermal designs.

Design and Development of Micro-Power Generating Device for Biomedical Applications of Lab-on-a-Disc.

PubMed

Joseph, Karunan; Ibrahim, Fatimah; Cho, Jongman; Thio, Tzer Hwai Gilbert; Al-Faqheri, Wisam; Madou, Marc

2015-01-01

The development of micro-power generators for centrifugal microfluidic discs enhances the platform as a green point-of-care diagnostic system and eliminates the need for attaching external peripherals to the disc. In this work, we present micro-power generators that harvest energy from the disc's rotational movement to power biomedical applications on the disc. To implement these ideas, we developed two types of micro-power generators using piezoelectric films and an electromagnetic induction system. The piezoelectric-based generator takes advantage of the film's vibration during the disc's rotational motion, whereas the electromagnetic induction-based generator operates on the principle of current generation in stacks of coil exposed to varying magnetic flux. We have successfully demonstrated that at the spinning speed of 800 revolutions per minute (RPM) the piezoelectric film-based generator is able to produce up to 24 microwatts using 6 sets of films and the magnetic induction-based generator is capable of producing up to 125 milliwatts using 6 stacks of coil. As a proof of concept, a custom made localized heating system was constructed to test the capability of the magnetic induction-based generator. The heating system was able to achieve a temperature of 58.62 °C at 2200 RPM. This development of lab-on-a-disc micro power generators preserves the portability standards and enhances the future biomedical applications of centrifugal microfluidic platforms.

High power heating of magnetic reconnection in merging tokamak experiments

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

Ono, Y.; Tanabe, H.; Gi, K.

2015-05-15

Significant ion/electron heating of magnetic reconnection up to 1.2 keV was documented in two spherical tokamak plasma merging experiment on MAST with the significantly large Reynolds number R∼10{sup 5}. Measured 1D/2D contours of ion and electron temperatures reveal clearly energy-conversion mechanisms of magnetic reconnection: huge outflow heating of ions in the downstream and localized heating of electrons at the X-point. Ions are accelerated up to the order of poloidal Alfven speed in the reconnection outflow region and are thermalized by fast shock-like density pileups formed in the downstreams, in agreement with recent solar satellite observations and PIC simulation results. The magneticmore » reconnection efficiently converts the reconnecting (poloidal) magnetic energy mostly into ion thermal energy through the outflow, causing the reconnection heating energy proportional to square of the reconnecting (poloidal) magnetic field B{sub rec}{sup 2}  ∼  B{sub p}{sup 2}. The guide toroidal field B{sub t} does not affect the bulk heating of ions and electrons, probably because the reconnection/outflow speeds are determined mostly by the external driven inflow by the help of another fast reconnection mechanism: intermittent sheet ejection. The localized electron heating at the X-point increases sharply with the guide toroidal field B{sub t}, probably because the toroidal field increases electron confinement and acceleration length along the X-line. 2D measurements of magnetic field and temperatures in the TS-3 tokamak merging experiment also reveal the detailed reconnection heating mechanisms mentioned above. The high-power heating of tokamak merging is useful not only for laboratory study of reconnection but also for economical startup and heating of tokamak plasmas. The MAST/TS-3 tokamak merging with B{sub p} > 0.4 T will enables us to heat the plasma to the alpha heating regime: T{sub i} > 5 keV without using any additional heating facility.« less

Temperature modulation with an esophageal heat transfer device - a pediatric swine model study.

PubMed

Kulstad, Erik B; Naiman, Melissa; Shanley, Patrick; Garrett, Frank; Haryu, Todd; Waller, Donald; Azarafrooz, Farshid; Courtney, Daniel Mark

2015-01-01

An increasing number of conditions appear to benefit from control and modulation of temperature, but available techniques to control temperature often have limitations, particularly in smaller patients with high surface to mass ratios. We aimed to evaluate a new method of temperature modulation with an esophageal heat transfer device in a pediatric swine model, hypothesizing that clinically significant modulation in temperature (both increases and decreases of more than 1°C) would be possible. Three female Yorkshire swine averaging 23 kg were anesthetized with inhalational isoflurane prior to placement of the esophageal device, which was powered by a commercially available heat exchanger. Swine temperature was measured rectally and cooling and warming were performed by selecting the appropriate external heat exchanger mode. Temperature was recorded over time in order to calculate rates of temperature change. Histopathology of esophageal tissue was performed after study completion. Average swine baseline temperature was 38.3°C. Swine #1 exhibited a cooling rate of 3.5°C/hr; however, passive cooling may have contributed to this rate. External warming blankets maintained thermal equilibrium in swine #2 and #3, demonstrating maximum temperature decrease of 1.7°C/hr. Warming rates averaged 0.29°C/hr. Histopathologic analysis of esophageal tissue showed no adverse effects. An esophageal heat transfer device successfully modulated the temperature in a pediatric swine model. This approach to temperature modulation may offer a useful new modality to control temperature in conditions warranting temperature management (such as maintenance of normothermia, induction of hypothermia, fever control, or malignant hyperthermia).

Irreversible Brownian Heat Engine

NASA Astrophysics Data System (ADS)

Taye, Mesfin Asfaw

2017-10-01

We model a Brownian heat engine as a Brownian particle that hops in a periodic ratchet potential where the ratchet potential is coupled with a linearly decreasing background temperature. We show that the efficiency of such Brownian heat engine approaches the efficiency of endoreversible engine η =1-√{{Tc/Th}} [23]. On the other hand, the maximum power efficiency of the engine approaches η ^{MAX}=1-({Tc/Th})^{1\\over 4}. It is shown that the optimized efficiency always lies between the efficiency at quasistatic limit and the efficiency at maximum power while the efficiency at maximum power is always less than the optimized efficiency since the fast motion of the particle comes at the expense of the energy cost. If the heat exchange at the boundary of the heat baths is included, we show that such a Brownian heat engine has a higher performance when acting as a refrigerator than when operating as a device subjected to a piecewise constant temperature. The role of time on the performance of the motor is also explored via numerical simulations. Our numerical results depict that the time t and the external load dictate the direction of the particle velocity. Moreover, the performance of the heat engine improves with time. At large t (steady state), the velocity, the efficiency and the coefficient of performance of the refrigerator attain their maximum value. Furthermore, we study the effect of temperature by considering a viscous friction that decreases exponentially as the background temperature increases. Our result depicts that the Brownian particle exhibits a fast unidirectional motion when the viscous friction is temperature dependent than that of constant viscous friction. Moreover, the efficiency of this motor is considerably enhanced when the viscous friction is temperature dependent. On the hand, the motor exhibits a higher performance of the refrigerator when the viscous friction is taken to be constant.

Mathematical estimation of melt depth in conduction mode of laser spot remelting process

NASA Astrophysics Data System (ADS)

Hadi, Iraj

2012-12-01

A one-dimensional mathematical model based on the front tracking method was developed to predict the melt depth as a function of internal and external parameters of laser spot remelting process in conduction mode. Power density, pulse duration, and thermophysical properties of material including thermal diffusivity, melting point, latent heat, and absorption coefficient have been taken into account in the model of this article. By comparing the theoretical results and experimental welding data of commercial pure nickel and titanium plates, the validity of the developed model was examined. Comparison shows a reasonably good agreement between the theory and experiment. For the sake of simplicity, a graphical technique was presented to obtain the melt depth of various materials at any arbitrary amount of power density and pulse duration. In the graphical technique, two dimensionless constants including the Stefan number (Ste) and an introduced constant named laser power factor (LPF) are used. Indeed, all of the internal and external parameters have been gathered in LPF. The effect of power density and pulse duration on the variation of melt depth for different materials such as aluminum, copper, and stainless steel were investigated. Additionally, appropriate expressions were extracted to describe the minimum power density and time to reach melting point in terms of process parameters. A simple expression is also extracted to estimate the thickness of mushy zone for alloys.

Relative contributions of external forcing factors to circulation and hydrographic properties in a micro-tidal bay

NASA Astrophysics Data System (ADS)

Yoon, Seokjin; Kasai, Akihide

2017-11-01

The dominant external forcing factors influencing estuarine circulation differ among coastal environments. A three-dimensional regional circulation model was developed to estimate external influence indices and relative contributions of external forcing factors such as external oceanic forcing, surface heat flux, wind stress, and river discharge to circulation and hydrographic properties in Tango Bay, Japan. Model results show that in Tango Bay, where the Tsushima Warm Current passes offshore of the bay, under conditions of strong seasonal winds and river discharge, the water temperature and salinity are strongly influenced by surface heat flux and river discharge in the surface layer, respectively, while in the middle and bottom layers both are mainly controlled by open boundary conditions. The estuarine circulation is comparably influenced by all external forcing factors, the strong current, surface heat flux, wind stress, and river discharge. However, the influence degree of each forcing factor varies with temporal variations in external forcing factors as: the influence of open boundary conditions is higher in spring and early summer when the stronger current passes offshore of the bay, that of surface heat flux reflects the absolute value of surface heat flux, that of wind stress is higher in late fall and winter due to strong seasonal winds, and that of river discharge is higher in early spring due to snow-melting and summer and early fall due to flood events.

Heat pump water heater and storage tank assembly

DOEpatents

Dieckmann, John T.; Nowicki, Brian J.; Teagan, W. Peter; Zogg, Robert

1999-09-07

A water heater and storage tank assembly comprises a housing defining a chamber, an inlet for admitting cold water to the chamber, and an outlet for permitting flow of hot water from the chamber. A compressor is mounted on the housing and is removed from the chamber. A condenser comprises a tube adapted to receive refrigerant from the compressor, and winding around the chamber to impart heat to water in the chamber. An evaporator is mounted on the housing and removed from the chamber, the evaporator being adapted to receive refrigerant from the condenser and to discharge refrigerant to conduits in communication with the compressor. An electric resistance element extends into the chamber, and a thermostat is disposed in the chamber and is operative to sense water temperature and to actuate the resistance element upon the water temperature dropping to a selected level. The assembly includes a first connection at an external end of the inlet, a second connection at an external end of the outlet, and a third connection for connecting the resistance element, compressor and evaporator to an electrical power source.

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).

Safe atmosphere entry of an isotope heat source with a single stable trim attitude at hypersonic speeds

NASA Technical Reports Server (NTRS)

Levy, L. L., Jr.; Burns, R. K.

1972-01-01

A theoretical investigation has been made to design an isotope heat source capable of satisfying the conflicting thermal requirements of steady-state operation and atmosphere entry. The isotope heat source must transfer heat efficiently to a heat exchange during normal operation with a power system in space, and in the event of a mission abort, it must survive the thermal environment of atmosphere entry and ground impact without releasing radioactive material. A successful design requires a compatible integration of the internal components of the heat source with the external aerodynamic shape. To this end, configurational, aerodynamic, motion, and thermal analyses were coupled and iterated during atmosphere entries at suborbital through superorbital velocities at very shallow and very steep entry angles. Results indicate that both thermal requirements can be satisfied by a heat source which has a single stable aerodynamic orientation at hypersonic speeds. For such a design, the insulation material required to adequately protect the isotope fuel from entry heating need extend only half way around the fuel capsule on the aerodynamically stable (wind-ward) side of the heat source. Thus, a low-thermal-resistance, conducting heat path is provided on the opposite side of the heat source through which heat can be transferred to an adjacent heat exchanger during normal operation without exceeding specified temperature limits.

Otto engine beyond its standard quantum limit.

PubMed

Leggio, Bruno; Antezza, Mauro

2016-02-01

We propose a quantum Otto cycle based on the properties of a two-level system in a realistic out-of-thermal-equilibrium electromagnetic field acting as its sole reservoir. This steady configuration is produced without the need of active control over the state of the environment, which is a noncoherent thermal radiation, sustained only by external heat supplied to macroscopic objects. Remarkably, even for nonideal finite-time transformations, it largely over-performs the standard ideal Otto cycle and asymptotically achieves unit efficiency at finite power.

Multifunctional superparamagnetic nanocrystals for imaging and targeted drug delivery to the lung

NASA Astrophysics Data System (ADS)

Armijo, Leisha M.; Brandt, Yekaterina I.; Withers, Nathan J.; Plumley, John B.; Cook, Nathaniel C.; Rivera, Antonio C.; Yadav, Surabhi; Smolyakov, Gennady A.; Monson, Todd; Huber, Dale L.; Smyth, Hugh D. C.; Osiński, Marek

2012-03-01

Iron oxide colloidal nanocrystals (ferrofluids) are investigated for application in the treatment of cystic fibrosis lung infections, the leading cause of mortality in cystic fibrosis patients. We investigate the use of iron oxide nanocrystals to increase the effectiveness of inhalation aerosol antibiotics therapy through two mechanisms: directed particle movement in the presence of a static external magnetic field and magnetic hyperthermia. Magnetic hyperthermia is an effective method for decreasing the viscosity of the mucus and biofilm thereby increasing drug, immune cell, and antibody penetration to the affected area. Iron oxide nanocrystals of various sizes and morphologies were synthesized and tested for specific losses (heating power) using frequencies of 111.1 kHz and 629.2 kHz, and corresponding magnetic field strengths of 9 and 25 mT. Nanocrystals in the superparamagnetic to ferromagnetic size range exhibited excellent heating power. Additionally, iron oxide-zinc selenide core-shell nanoparticles were prepared in parallel in order to allow imaging of the iron oxide nanoparticles.

Iron Oxide Nanocrystals for Magnetic Hyperthermia Applications

PubMed Central

Armijo, Leisha M.; Brandt, Yekaterina I.; Mathew, Dimple; Yadav, Surabhi; Maestas, Salomon; Rivera, Antonio C.; Cook, Nathaniel C.; Withers, Nathan J.; Smolyakov, Gennady A.; Adolphi, Natalie; Monson, Todd C.; Huber, Dale L.; Smyth, Hugh D. C.; Osiński, Marek

2012-01-01

Magnetic nanocrystals have been investigated extensively in the past several years for several potential applications, such as information technology, MRI contrast agents, and for drug conjugation and delivery. A specific property of interest in biomedicine is magnetic hyperthermia—an increase in temperature resulting from the thermal energy released by magnetic nanocrystals in an external alternating magnetic field. Iron oxide nanocrystals of various sizes and morphologies were synthesized and tested for specific losses (heating power) using frequencies of 111.1 kHz and 629.2 kHz, and corresponding magnetic field strengths of 9 and 25 mT. Polymorphous nanocrystals as well as spherical nanocrystals and nanowires in paramagnetic to ferromagnetic size range exhibited good heating power. A remarkable 30 °C temperature increase was observed in a nanowire sample at 111 kHz and magnetic field of 25 mT (19.6 kA/m), which is very close to the typical values of 100 kHz and 20 mT used in medical treatments. PMID:28348300

Heat Transfer Measurements and Predictions on a Power Generation Gas Turbine Blade

NASA Technical Reports Server (NTRS)

Giel, Paul W.; Bunker, Ronald S.; VanFossen, G. James; Boyle, Robert J.

2000-01-01

Detailed heat transfer measurements and predictions are given for a power generation turbine rotor with 129 deg of nominal turning and an axial chord of 137 mm. Data were obtained for a set of four exit Reynolds numbers comprised of the design point of 628,000, -20%, +20%, and +40%. Three ideal exit pressure ratios were examined including the design point of 1.378, -10%, and +10%. Inlet incidence angles of 0 deg and +/-2 deg were also examined. Measurements were made in a linear cascade with highly three-dimensional blade passage flows that resulted from the high flow turning and thick inlet boundary layers. Inlet turbulence was generated with a blown square bar grid. The purpose of the work is the extension of three-dimensional predictive modeling capability for airfoil external heat transfer to engine specific conditions including blade shape, Reynolds numbers, and Mach numbers. Data were obtained by a steady-state technique using a thin-foil heater wrapped around a low thermal conductivity blade. Surface temperatures were measured using calibrated liquid crystals. The results show the effects of strong secondary vortical flows, laminar-to-turbulent transition, and also show good detail in the stagnation region.

Externally triggered microcapsules

NASA Technical Reports Server (NTRS)

Mosier, Benjamin (Inventor); Morrison, Dennis R. (Inventor)

2011-01-01

Disclosed are microcapsules comprising a polymer shell enclosing one or more immiscible liquid phases in which a drug or drug precursor are contained in a liquid phase. The microparticles also contain magnetic particles that can be heated by application of an external magnetic field and thus heated to a predetermined Curie temperature. Heating of the particles melts the polymer shell and releases the drug without causing heating of surrounding tissues.

A thin gold coated hydrogen heat pipe-cryogenic target for external experiments at COSY

NASA Astrophysics Data System (ADS)

Abdel-Bary, M.; Abdel-Samad, S.; Elawadi, G. A.; Kilian, K.; Ritman, J.

2009-05-01

A gravity assisted Gold coated heat pipe (GCHP) with 5-mm diameter has been developed and tested to cool a liquid hydrogen target for external beam experiments at COSY. The need for a narrow target diameter leads us to study the effect of reducing the heat pipe diameter to 5 mm instead of 7 mm, to study the effect of coating the external surface of the heat pipe by a shiny gold layer (to decrease the radiation heat load), and to study the effect of using the heat pipe without using 20 layers of' super-insulation around it (aluminized Mylar foil) to keep the target diameter as small as possible. The developed gold coated heat pipe was tested with 20 layers of super-insulation (WI) and without super-insulation (WOI). The operating characteristics for both conditions were compared to show the advantages and disadvantages.

Reduced junction temperature and enhanced performance of high power light-emitting diodes using reduced graphene oxide pattern

NASA Astrophysics Data System (ADS)

Han, Nam; Jung, Eunjin; Han, Min; Deul Ryu, Beo; Bok Ko, Kang; Park, Young Jae; Cuong, TranViet; Cho, Jaehee; Kim, Hyunsoo; Hong, Chang-Hee

2015-07-01

Thermal management has become a crucial area for further development of high-power light-emitting didoes (LEDs) due to the high operating current densities that are required and result in additional joule heating. This increased joule heating negatively affects the performance of the LEDs since it greatly decreases both the optical performance and the lifetime. To circumvent this problem, a reduced graphene oxide (rGO) layer can be inserted to act as a heat spreader. In this study, current-voltage and light-output-current measurements are systematically performed at different temperatures from 30 to 190 °C to investigate the effect that the embedded rGO pattern has on the device performance. At a high temperature and high operating current, the junction temperature (Tj) is 23% lower and the external quantum efficiency (EQE) is 24% higher for the rGO embedded LEDs relative to those of conventional LEDs. In addition, the thermal activation energy of the rGO embedded LEDs exhibits a 30% enhancement as a function of the temperature at a bias of  -5 V. This indicates that the rGO pattern plays an essential role in decreasing the junction temperature and results in a favorable performance in terms of the temperature of the high power GaN-based LED junction.

Space shuttle heat pipe thermal control systems

NASA Technical Reports Server (NTRS)

Alario, J.

1973-01-01

Heat pipe (HP) thermal control systems designed for possible space shuttle applications were built and tested under this program. They are: (1) a HP augmented cold rail, (2) a HP/phase change material (PCM) modular heat sink and (3) a HP radiating panel for compartment temperature control. The HP augmented cold rail is similar to a standard two-passage fluid cold rail except that it contains an integral, centrally located HP throughout its length. The central HP core helps to increase the local power density capability by spreading concentrated heat inputs over the entire rail. The HP/PCM modular heat sink system consists of a diode HP connected in series to a standard HP that has a PCM canister attached to its mid-section. It is designed to connect a heat source to a structural heat sink during normal operation, and to automatically decouple from it and sink to the PCM whenever structural temperatures are too high. The HP radiating panel is designed to conductively couple the panel feeder HPs directly to a fluid line that serves as a source of waste heat. It is a simple strap-on type of system that requires no internal or external line modifications to distribute the heat to a large radiating area.

Resonant electrodynamic heating of stellar coronal loops: An LRC circuit analogue

NASA Technical Reports Server (NTRS)

Ionson, J. A.

1980-01-01

The electrodynamic coupling of stellar coronal loops to underlying beta velocity fields. A rigorous analysis revealed that the physics can be represented by a simple yet equivalent LRC circuit analogue. This analogue points to the existence of global structure oscillations which resonantly excite internal field line oscillations at a spatial resonance within the coronal loop. Although the width of this spatial resonance, as well as the induced currents and coronal velocity field, explicitly depend upon viscosity and resistivity, the resonant form of the generalized electrodynamic heating function is virtually independent of irreversibilities. This is a classic feature of high quality resonators that are externally driven by a broad band source of spectral power. Applications to solar coronal loops result in remarkable agreement with observations.

Aerodynamic Heat-Power Engine Operating on a Closed Cycle

NASA Technical Reports Server (NTRS)

Ackeret, J.; Keller, D. C.

1942-01-01

Hot-air engines with dynamic compressors and turbines offer new prospects of success through utilization of units of high efficiencies and through the employment of modern materials of great strength at high temperature. Particular consideration is given to an aerodynamic prime mover operating on a closed circuit and heated externally. Increase of the pressure level of the circulating air permits a great increase of limit load of the unit. This also affords a possibility of regulation for which the internal efficiency of the unit changes but slightly. The effect of pressure and temperature losses is investigated. A general discussion is given of the experimental installation operating at the Escher Wyss plant in Zurich for a considerable time at high temperatures.

Energy Recovery

NASA Technical Reports Server (NTRS)

1987-01-01

The United States and other countries face the problem of waste disposal in an economical, environmentally safe manner. A widely applied solution adopted by Americans is "waste to energy," incinerating the refuse and using the steam produced by trash burning to drive an electricity producing generator. NASA's computer program PRESTO II, (Performance of Regenerative Superheated Steam Turbine Cycles), provides power engineering companies, including Blount Energy Resources Corporation of Alabama, with the ability to model such features as process steam extraction, induction and feedwater heating by external sources, peaking and high back pressure. Expansion line efficiency, exhaust loss, leakage, mechanical losses and generator losses are used to calculate the cycle heat rate. The generator output program is sufficiently precise that it can be used to verify performance quoted in turbine generator supplier's proposals.

Three-dimensional thermal finite element modeling of lithium-ion battery in thermal abuse application

NASA Astrophysics Data System (ADS)

Guo, Guifang; Long, Bo; Cheng, Bo; Zhou, Shiqiong; Xu, Peng; Cao, Binggang

In order to better understand the thermal abuse behavior of high capacities and large power lithium-ion batteries for electric vehicle application, a three-dimensional thermal model has been developed for analyzing the temperature distribution under abuse conditions. The model takes into account the effects of heat generation, internal conduction and convection, and external heat dissipation to predict the temperature distribution in a battery. Three-dimensional model also considers the geometrical features to simulate oven test, which are significant in larger cells for electric vehicle application. The model predictions are compared to oven test results for VLP 50/62/100S-Fe (3.2 V/55 Ah) LiFePO 4/graphite cells and shown to be in great agreement.

Results of a M = 5.3 heat transfer test of the integrated vehicle using phase-change paint techniques on the 0.0175-scale model 56-OTS in the NASA/Ames Research Center 3.5-foot hypersonic wind tunnel

NASA Technical Reports Server (NTRS)

Marroquin, J.

1985-01-01

An experimental investigation was performed in the NASA/Ames Research Center 3.5-foot Hypersonic Wind Tunnel to obtain supersonic heat-distribution data in areas between the orbiter and external tank using phase-change paint techniques. The tests used Novamide SSV Model 56-OTS in the first and second-stage ascent configurations. Data were obtained at a nominal Mach number of 5.3 and a Reynolds number per foot of 5 x 10 to the 6th power with angles of attack of 0 deg, +/- 5 deg, and sideslip angles of 0 deg and +/- 5 deg.

External Cooling Coupled to Reduced Extremity Pressure Device

NASA Technical Reports Server (NTRS)

Kuznetz, Lawrence H.

2011-01-01

Although suited astronauts are currently cooled with a Liquid Cooled Ventilation Garment (LCVG), which can remove up to 85 percent of body heat, their effectiveness is limited because cooling must penetrate layers of skin, muscle, fat, bone, and tissue to reach the bloodstream, where its effect is prominent. Vasoconstriction further reduces the effectiveness by limiting arterial flow when exposed to cold (the frostbite response), resulting in a time constant on the order of 20 minutes from application to maximum effect. This delay can be crucial in severe exposure to hypo- or hyper-thermic conditions, compromising homeostasis. The purpose of this innovation is to provide a lightweight, effective means of delivering heat or cold from an external source directly to the bloodstream. The effectiveness of this ECCREP (External Cooling Coupled to Reduced Extremity Pressure) device is based on not having to penetrate layers of skin, muscle, fat, and tissue, thereby avoiding the thermal lag associated with their mass and heat capacity. This is accomplished by means of an outer boot operating at a slightly reduced pressure than the rest of the body, combined with an inner boot cooled or heated by an external source via water or chemicals. Heat transfer from the external source to the foot takes place by means of circulating water or flexible heat pipes.

Nanowire-based thermoelectric ratchet in the hopping regime

NASA Astrophysics Data System (ADS)

Bosisio, Riccardo; Fleury, Geneviève; Pichard, Jean-Louis; Gorini, Cosimo

2016-04-01

We study a thermoelectric ratchet consisting of an array of disordered nanowires arranged in parallel on top of an insulating substrate and contacted asymmetrically to two electrodes. Transport is investigated in the Mott hopping regime, when localized electrons can propagate through the nanowires via thermally assisted hops. When the electronic temperature in the nanowires is different from the phononic one in the substrate, we show that a finite electrical current is generated even in the absence of driving forces between the electrodes. We discuss the device performance both as an energy harvester, when an excess heat from the substrate is converted into useful power, and as a refrigerator, when an external power is supplied to cool down the substrate.

Equation of state of liquid Indium under high pressure

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

Li, Huaming, E-mail: huamingli@gatech.edu, E-mail: mo.li@gatech.edu; Li, Mo, E-mail: huamingli@gatech.edu, E-mail: mo.li@gatech.edu; School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332

2015-09-15

We apply an equation of state of a power law form to liquid Indium to study its thermodynamic properties under high temperature and high pressure. Molar volume of molten indium is calculated along the isothermal line at 710K within good precision as compared with the experimental data in an externally heated diamond anvil cell. Bulk modulus, thermal expansion and internal pressure are obtained for isothermal compression. Other thermodynamic properties are also calculated along the fitted high pressure melting line. While our results suggest that the power law form may be a better choice for the equation of state of liquids,more » these detailed predictions are yet to be confirmed by further experiment.« less

Computer simulation of thermal and fluid systems for MIUS integration and subsystems test /MIST/ laboratory. [Modular Integrated Utility System

NASA Technical Reports Server (NTRS)

Rochelle, W. C.; Liu, D. K.; Nunnery, W. J., Jr.; Brandli, A. E.

1975-01-01

This paper describes the application of the SINDA (systems improved numerical differencing analyzer) computer program to simulate the operation of the NASA/JSC MIUS integration and subsystems test (MIST) laboratory. The MIST laboratory is designed to test the integration capability of the following subsystems of a modular integrated utility system (MIUS): (1) electric power generation, (2) space heating and cooling, (3) solid waste disposal, (4) potable water supply, and (5) waste water treatment. The SINDA/MIST computer model is designed to simulate the response of these subsystems to externally impressed loads. The computer model determines the amount of recovered waste heat from the prime mover exhaust, water jacket and oil/aftercooler and from the incinerator. This recovered waste heat is used in the model to heat potable water, for space heating, absorption air conditioning, waste water sterilization, and to provide for thermal storage. The details of the thermal and fluid simulation of MIST including the system configuration, modes of operation modeled, SINDA model characteristics and the results of several analyses are described.

Numerical study on the thermal management system of a liquid metal battery module

NASA Astrophysics Data System (ADS)

Guo, Zhenlin; Xu, Cheng; Li, Wei; Zhu, Fangfang; Li, Haomiao; Wang, Kangli; Cheng, Shijie; Jiang, Kai

2018-07-01

Liquid metal battery (LMB), with three-liquid-layer structure and high operating temperature (300-700 °C), is a newly emerging technology for large scale energy storage applications. A thermal management system is critical to achieve satisfied LMB performance and extend the life of batteries. In this work, an improved coupling model composing of a 3D heat-transfer model and a 1D electrochemical model is developed for the thermal analysis of a Li||Sb-Sn LMBs module (5.5 kWh). Key results including transient values, the contribution ratio of heat sources, temperature homogeneity and distribution, as well as the energy efficiency of the battery module, are presented. Based on the coupling model, the changeable-power-heating mode, sand filling material and vacuum insulation are further proposed to achieve the high energy efficiency and optimal performance of the LMBs module. Moreover, the LMBs module can achieve "self-heating" when operated at 0.2 C charge/discharge, under the vacuum insulation (0.01 W m-1 K-1 thermal conductivity, 100 mm thickness), requiring no external heating to keep the batteries at operating temperature.

Method for forming synthesis gas using a plasma-catalyzed fuel reformer

DOEpatents

Hartvigsen, Joseph J; Elangovan, S; Czernichowski, Piotr; Hollist, Michele

2015-04-28

A method of forming a synthesis gas utilizing a reformer is disclosed. The method utilizes a reformer that includes a plasma zone to receive a pre-heated mixture of reactants and ionize the reactants by applying an electrical potential thereto. A first thermally conductive surface surrounds the plasma zone and is configured to transfer heat from an external heat source into the plasma zone. The reformer further includes a reaction zone to chemically transform the ionized reactants into synthesis gas comprising hydrogen and carbon monoxide. A second thermally conductive surface surrounds the reaction zone and is configured to transfer heat from the external heat source into the reaction zone. The first thermally conductive surface and second thermally conductive surface are both directly exposed to the external heat source. A corresponding apparatus and system are also disclosed herein.

Examination of electromagnetic powers with the example of a uc(Faraday) disc dynamo

NASA Astrophysics Data System (ADS)

Reich, Felix A.; Müller, Wolfgang H.

2018-03-01

This paper studies the mathematical form of electromagnetic powers and their influence on the balance of energy by using the example of a uc(Faraday) disc. First, two forms of energy (and balances thereof) are discussed. These employ different forms of powers, which can be distinguished w.r.t. their physical origins and their interpretations in context with the notions of supply and production. The stationary uc(Faraday) disc experiment is modeled following the description by Kovetz (Electromagnetic theory, Oxford University Press, Oxford, 2000). Concepts for formulating the electromagnetic field equations for the rotating disc are discussed, and the corresponding approximate analytical solutions are presented. Based on the obtained electromagnetic fields, the powers of the disc are analyzed for a stationary process. The conversion of mechanical power to heating and electromagnetic powering of an external resistor is explained. The paper concludes with the computation of the time evolution of the angular velocity for a magnetically induced breaking process of the disc.

Lunar base thermal management/power system analysis and design

NASA Technical Reports Server (NTRS)

Mcghee, Jerry R.

1992-01-01

A compilation of several lunar surface thermal management and power system studies completed under contract and IR&D is presented. The work includes analysis and preliminary design of all major components of an integrated thermal management system, including loads determination, active internal acquisition and transport equipment, external transport systems (active and passive), passive insulation, solar shielding, and a range of lunar surface radiator concepts. Several computer codes were utilized in support of this study, including RADSIM to calculate radiation exchange factors and view factors, RADIATOR (developed in-house) for heat rejection system sizing and performance analysis over a lunar day, SURPWER for power system sizing, and CRYSTORE for cryogenic system performance predictions. Although much of the work was performed in support of lunar rover studies, any or all of the results can be applied to a range of surface applications. Output data include thermal loads summaries, subsystem performance data, mass, and volume estimates (where applicable), integrated and worst-case lunar day radiator size/mass and effective sink temperatures for several concepts (shielded and unshielded), and external transport system performance estimates for both single and two-phase (heat pumped) transport loops. Several advanced radiator concepts are presented, along with brief assessments of possible system benefits and potential drawbacks. System point designs are presented for several cases, executed in support of the contract and IR&D studies, although the parametric nature of the analysis is stressed to illustrate applicability of the analysis procedure to a wide variety of lunar surface systems. The reference configuration(s) derived from the various studies will be presented along with supporting criteria. A preliminary design will also be presented for the reference basing scenario, including qualitative data regarding TPS concerns and issues.

Achieving quasi-adiabatic thermal environment to maximize resolution power in very high-pressure liquid chromatography: Theory, models, and experiments.

PubMed

Gritti, Fabrice; Gilar, Martin; Jarrell, Joseph A

2016-04-29

A cylindrical vacuum chamber (inner diameter 5 cm) housing a narrow-bore 2.1 mm×100 mm column packed with 1.8 μm HSS-T3 fully porous particles was built in order to isolate thermally the chromatographic column from the external air environment. Consistent with statistical physics and the mean free path of air molecules, the experimental results show that natural air convection and conduction are fully eliminated for housing air pressures smaller than 10(-4) Torr. Heat radiation is minimized by wrapping up the column with low-emissivity aluminum-tape (emissivity coefficient ϵ=0.03 vs. 0.28 for polished stainless steel 316). Overall, the heat flux at the column wall is reduced by 96% with respect to standard still-air ovens. From a practical viewpoint, the efficiency of the column run at a flow rate of 0.6 mL/min at a constant 13,000 psi pressure drop (the viscous heat power is around 9 W/m) is improved by up to 35% irrespective of the analyte retention. Models of heat and mass transfer reveal that (1) the amplitude of the radial temperature gradient is significantly reduced from 0.30 to 0.01 K and (2) the observed improvement in resolution power stems from a more uniform distribution of the flow velocity across the column diameter. The eddy dispersion term in the van Deemter equation is reduced by 0.8±0.1 reduced plate height unit, a significant gain in column performance. Copyright © 2016 Elsevier B.V. All rights reserved.

Nuclear Air-Brayton Combined Cycle Power Conversion Design, Physical Performance Estimation and Economic Assessment

NASA Astrophysics Data System (ADS)

Andreades, Charalampos

The combination of an increased demand for electricity for economic development in parallel with the widespread push for adoption of renewable energy sources and the trend toward liberalized markets has placed a tremendous amount of stress on generators, system operators, and consumers. Non-guaranteed cost recovery, intermittent capacity, and highly volatile market prices are all part of new electricity grids. In order to try and remediate some of these effects, this dissertation proposes and studies the design and performance, both physical and economic, of a novel power conversion system, the Nuclear Air-Brayton Combined Cycle (NACC). The NACC is a power conversion system that takes a conventional industrial frame type gas turbine, modifies it to accept external nuclear heat at 670°C, while also maintaining its ability to co-fire with natural gas to increase temperature and power output at a very quick ramp rate. The NACC addresses the above issues by allowing the generator to gain extra revenue through the provision of ancillary services in addition to energy payments, the grid operator to have a highly flexible source of capacity to back up intermittent renewable energy sources, and the consumer to possibly see less volatile electricity prices and a reduced probability of black/brown outs. This dissertation is split into six sections that delve into specific design and economic issues related to the NACC. The first section describes the basic design and modifications necessary to create a functional externally heated gas turbine, sets a baseline design based upon the GE 7FB, and estimates its physical performance under nominal conditions. The second section explores the off-nominal performance of the NACC and characterizes its startup and shutdown sequences, along with some of its safety measures. The third section deals with the power ramp rate estimation of the NACC, a key performance parameter in a renewable-heavy grid that needs flexible capacity. The fourth section lays out the cost structure of the Mk1 Pebble-Bed Fluoride-salt-cooled High-temperature Reactor (FHR) with the NACC, since the NACC cannot be treated separately from its heat source. The fifth section evaluates the cost structure of a twelve-unit Mk1 FHR and NACC, including capital construction costs, operating costs, fuel and decommissioning costs in bottom up methodology. The sixth section proposes alternative NACC configurations and scales (mobile, remote NACC) or alternative power cycles to the NACC that can be coupled to the FHR (supercritical carbon dioxide Brayton cycle).

External heating of stents by radio waves Pilot studies in rabbit aorta

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

Levitt, Adam B.; Robinson, Keith; Chronos, Nicolas A.F.

Purpose: This experiment was designed to assess the feasibility of radio frequency energy delivered by a prototype radio frequency generator inductive heating device (REVAX) positioned external to the body, for transient heating of stents after arterial implant. Methods and Materials: Twenty-one New Zealand White rabbits underwent stenting of their infrarenal aorta. Nine rabbits were stented and immediately placed in the REVAX for external stent heating with internal temperature probes in place. Twelve rabbits were stented and 3 days later either heated or placed in the generator as a sham for 20 min. The animals were terminated 28 days later. Results:more » The REVAX was able to heat the aortic stents in a controlled fashion; in Phase II experiments, the stent temperature was raised to 42 deg. C for 20 min. In Phase I mild necrosis was noted at the stent struts. In Phase II, necrosis and mineralization of the media was seen at the stent struts, and evidence of neointimal suppression was observed. Conclusion: This study demonstrated that external heating of stents in a blood vessel in a live animal via radio frequency energy is feasible. Further studies will be needed to assess whether any specific heating regimen might inhibit fibrocellular neointimal hyperplasia.« less

External Heat Transfer Coefficient Measurements on a Surrogate Indirect Inertial Confinement Fusion Target

DOE PAGES

Miles, Robin; Havstad, Mark; LeBlanc, Mary; ...

2015-09-15

External heat transfer coefficients were measured around a surrogate Indirect inertial confinement fusion (ICF) based on the Laser Inertial Fusion Energy (LIFE) design target to validate thermal models of the LIFE target during flight through a fusion chamber. Results indicate that heat transfer coefficients for this target 25-50 W/m 2∙K are consistent with theoretically derived heat transfer coefficients and valid for use in calculation of target heating during flight through a fusion chamber.

Hysteresis and fast timescales in transport relations of toroidal plasmas

NASA Astrophysics Data System (ADS)

Itoh, K.; Itoh, S.-I.; Ida, K.; Inagaki, S.; Kamada, Y.; Kamiya, K.; Dong, J. Q.; Hidalgo, C.; Evans, T.; Ko, W. H.; Park, H.; Tokuzawa, T.; Kubo, S.; Kobayashi, T.; Kosuga, Y.; Sasaki, M.; Yun, G. S.; Song, S. D.; Kasuya, N.; Nagashima, Y.; Moon, C.; Yoshinuma, M.; Makino, R.; Tsujimura, T.; Tsuchiya, H.; Stroth, U.

2017-10-01

This article assesses current understanding of hysteresis in transport relations, and its impact on the field. The rapid changes of fluxes compared to slow changes of plasma parameters are overviewed for both core and edge plasmas. The modulation ECH experiment is explained, in which the heating power cycles on-and-off periodically, revealing hysteresis and fast changes in the gradient-flux relation. The key finding is that hystereses were observed simultaneously in both the the gradient-flux and gradient-fluctuation relations. Hysteresis with rapid timescale exists in the channels of energy, electron and impurity densities, and plausibly in momentum. Advanced methods of data analysis are explained. Transport hysteresis can be studied by observing the higher harmonics of temperature perturbation δ Tm in heating modulation experiments. The hysteresis introduces the term δ Tm , which depends on the harmonic number m in an algebraic manner (not exponential decay). Next, the causes of hysteresis and its fast timescale are discussed. The nonlocal-in-space coupling works here, but does not suffice. One mechanism for ‘the heating heats turbulence’ is that the external source S in phase space for heating has its fluctuation in turbulent plasma. This coupling can induce the direct input of heating power into fluctuations. The height of the jump in transport hysteresis is smaller for heavier hydrogen isotopes, and could be one of the origins of isotope effects on confinement. Finally, the impacts of transport hysteresis on the control system are assessed. Control systems must be designed so as to protect the system from sudden plasma loss.

Jumping-droplet electronics hot-spot cooling

NASA Astrophysics Data System (ADS)

Oh, Junho; Birbarah, Patrick; Foulkes, Thomas; Yin, Sabrina L.; Rentauskas, Michelle; Neely, Jason; Pilawa-Podgurski, Robert C. N.; Miljkovic, Nenad

2017-03-01

Demand for enhanced cooling technologies within various commercial and consumer applications has increased in recent decades due to electronic devices becoming more energy dense. This study demonstrates jumping-droplet based electric-field-enhanced (EFE) condensation as a potential method to achieve active hot spot cooling in electronic devices. To test the viability of EFE condensation, we developed an experimental setup to remove heat via droplet evaporation from single and multiple high power gallium nitride (GaN) transistors acting as local hot spots (4.6 mm × 2.6 mm). An externally powered circuit was developed to direct jumping droplets from a copper oxide (CuO) nanostructured superhydrophobic surface to the transistor hot spots by applying electric fields between the condensing surface and the transistor. Heat transfer measurements were performed in ambient air (22-25 °C air temperature, 20%-45% relative humidity) to determine the effect of gap spacing (2-4 mm), electric field (50-250 V/cm) and applied heat flux (demonstrated to 13 W/cm2). EFE condensation was shown to enhance the heat transfer from the local hot spot by ≈200% compared to cooling without jumping and by 20% compared to non-EFE jumping. Dynamic switching of the electric field for a two-GaN system reveals the potential for active cooling of mobile hot spots. The opportunity for further cooling enhancement by the removal of non-condensable gases promises hot spot heat dissipation rates approaching 120 W/cm2. This work provides a framework for the development of active jumping droplet based vapor chambers and heat pipes capable of spatial and temporal thermal dissipation control.

Transport modeling of convection dominated helicon discharges in Proto-MPEX with the B2.5-Eirene code

NASA Astrophysics Data System (ADS)

Owen, L. W.; Rapp, J.; Canik, J.; Lore, J. D.

2017-11-01

Data-constrained interpretative analyses of plasma transport in convection dominated helicon discharges in the Proto-MPEX linear device, and predictive calculations with additional Electron Cyclotron Heating/Electron Bernstein Wave (ECH/EBW) heating, are reported. The B2.5-Eirene code, in which the multi-fluid plasma code B2.5 is coupled to the kinetic Monte Carlo neutrals code Eirene, is used to fit double Langmuir probe measurements and fast camera data in front of a stainless-steel target. The absorbed helicon and ECH power (11 kW) and spatially constant anomalous transport coefficients that are deduced from fitting of the probe and optical data are additionally used for predictive simulations of complete axial distributions of the densities, temperatures, plasma flow velocities, particle and energy fluxes, and possible effects of alternate fueling and pumping scenarios. The somewhat hollow electron density and temperature radial profiles from the probe data suggest that Trivelpiece-Gould wave absorption is the dominant helicon electron heating source in the discharges analyzed here. There is no external ion heating, but the corresponding calculated ion temperature radial profile is not hollow. Rather it reflects ion heating by the electron-ion equilibration terms in the energy balance equations and ion radial transport resulting from the hollow density profile. With the absorbed power and the transport model deduced from fitting the sheath limited discharge data, calculated conduction limited higher recycling conditions were produced by reducing the pumping and increasing the gas fueling rate, resulting in an approximate doubling of the target ion flux and reduction of the target heat flux.

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

Zhang, Chao; Santhanagopalan, Shriram; Sprague, Michael A.

Lithium-ion batteries are currently the state-of-the-art power sources for a variety of applications, from consumer electronic devices to electric-drive vehicles (EDVs). Being an energized component, failure of the battery is an essential concern, which can result in rupture, smoke, fire, or venting. The failure of Lithium-ion batteries can be due to a number of external abusive conditions (impact/crush, overcharge, thermal ramp, etc.) or internal conditions (internal short circuits, excessive heating due to resistance build-up, etc.), of which the mechanical-abuse-induced short circuit is a very practical problem. In order to better understand the behavior of Lithium-ion batteries under mechanical abuse, amore » coupled modeling methodology encompassing the mechanical, thermal and electrical response has been developed for predicting short circuit under external crush.« less

76 FR 57897 - Energy Conservation Program: Energy Conservation Standards for Certain External Power Supplies

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-19

... Energy Conservation Program: Energy Conservation Standards for Certain External Power Supplies AGENCY... external power supplies used in specific applications from certain energy conservation standards prescribed... external power supplies used either in security or life safety alarms or surveillance system components...

The effect of low ceiling on the external combustion of the cabin fire

NASA Astrophysics Data System (ADS)

Su, Shichuan; Chen, Changyun; Wang, Liang; Wei, Chengyin; Cui, Haibing; Guo, Chengyu

2018-06-01

External combustion is a phenomenon where the flame flares out of the window and burns outside. Because of the particularity of the ship's cabin structure, there is a great danger in the external combustion. In this paper, the numerical calculation and analysis of three kinds of low ceiling ship cabin fire are analyzed based on the large eddy numerical simulation technique. Through the analysis of temperature, flue gas velocity, heat flux density and so on, the external combustion phenomenon of fire development is calculated. The results show that when external combustion occurs, the amount of fuel escaping decreases with the roof height. The temperature above the window increases with the height of the ceiling. The heat flux density in the external combustion flame is mainly provided by radiation, and convection is only a small part; In the plume area there is a time period, in this time period, the convective heat flux density is greater than the radiation heat flux, this time with the ceiling height increases. No matter which ceiling height, the external combustion will seriously damage the structure of the ship after a certain period of time. The velocity distribution of the three roof is similar, but with the height of the ceiling, the area size is also increasing.

Thermoelectric energy harvesting for a solid waste processing toilet

NASA Astrophysics Data System (ADS)

Stokes, C. David; Baldasaro, Nicholas G.; Bulman, Gary E.; Stoner, Brian R.

2014-06-01

Over 2.5 billion people do not have access to safe and effective sanitation. Without a sanitary sewer infrastructure, self-contained modular systems can provide solutions for these people in the developing world and remote areas. Our team is building a better toilet that processes human waste into burnable fuel and disinfects the liquid waste. The toilet employs energy harvesting to produce electricity and does not require external electrical power or consumable materials. RTI has partnered with Colorado State University, Duke University, and Roca Sanitario under a Bill and Melinda Gates Foundation Reinvent the Toilet Challenge (RTTC) grant to develop an advanced stand-alone, self-sufficient toilet to effectively process solid and liquid waste. The system operates through the following steps: 1) Solid-liquid separation, 2) Solid waste drying and sizing, 3) Solid waste combustion, and 4) Liquid waste disinfection. Thermoelectric energy harvesting is a key component to the system and provides the electric power for autonomous operation. A portion of the exhaust heat is captured through finned heat-sinks and converted to electricity by thermoelectric (TE) devices to provide power for the electrochemical treatment of the liquid waste, pumps, blowers, combustion ignition, and controls.

EXPERIMENTAL EVALUATION OF THE THERMAL PERFORMANCE OF A WATER SHIELD FOR A SURFACE POWER REACTOR

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

REID, ROBERT S.; PEARSON, J. BOSIE; STEWART, ERIC T.

2007-01-16

Water based reactor shielding is being investigated for use on initial lunar surface power systems. A water shield may lower overall cost (as compared to development cost for other materials) and simplify operations in the setup and handling. The thermal hydraulic performance of the shield is of significant interest. The mechanism for transferring heat through the shield is natural convection. Natural convection in a 100 kWt lunar surface reactor shield design is evaluated with 2 kW power input to the water in the Water Shield Testbed (WST) at the NASA Marshall Space Flight Center. The experimental data from the WSTmore » is used to validate a CFD model. Performance of the water shield on the lunar surface is then predicted with a CFD model anchored to test data. The experiment had a maximum water temperature of 75 C. The CFD model with 1/6-g predicts a maximum water temperature of 88 C with the same heat load and external boundary conditions. This difference in maximum temperature does not greatly affect the structural design of the shield, and demonstrates that it may be possible to use water for a lunar reactor shield.« less

Electric properties of a textured BiNaKTiO3 ceramic for energy harvesting system

NASA Astrophysics Data System (ADS)

Lim, D. H.; Song, T. K.; Lee, D. S.; Jeong, S. J.; Kim, Min-Soo; Song, Jae-Sung

2012-01-01

Piezoelectric ceramics with microstructural texturing were fabricated and evaluated to investigate their possibility for use in piezoelectric energy harvest devices in response to external mechanical impact. The microstructural evolution and properties of a Bi0.5(Na0.425K0.075) TiO3 (BNKT) ceramic material with platelike Bi4Ti3O12 (BiT) were investigated. The platelike Bi4Ti3O12 (BiT) was used as a template to induce grain growth under a proper heat treatment. The textured BNKTs were fabricated and heated at 1150 °C for 10 h. They exhibited <001>-oriented large grains and improved of ferroelectric properties. The textured microstructure was due to the occurrence of grain growth around the templates. When subjected to a low stress of 0.8 MPa, the textured BNKT had a slightly larger voltage and power than the randomly-oriented BNKT. Meanwhile, when high stresses over 2 MPa were applied, the voltage and the power of the textured specimen were larger than those of the randomly-oriented specimen. The microstructure textured along the <100> direction may contribute to the improved power generation.

SOL and Edge Flows in DIII-D

NASA Astrophysics Data System (ADS)

Boedo, J. A.; Degrassie, J. S.; Grierson, B. A.; Rudakov, D. A.

2015-11-01

Recent measurements at DIII-D edge plasmas at the outer midplane show that, in the absence of external torque, the edge and near-SOL plasma flow is largely dominated by the intrinsic source of rotation most likely due to thermal ion loss. We also show that when NBI heating is present, the core momentum competes with the edge intrinsic momentum and can overwhelm it, in short, NBI-heated discharges at high power tend to determine edge and near SOL flows. Experiments performed in the DIII-D tokamak with OH heated, ECH-heated and NBI-heated discharges are diagnosed for core plasma flow with CER and edge/SOL plasma flow with Mach probes. We have changed the amount of NBI, OH and ECH heating while scanning the discharge collisionality. We have compared the experimental measurements to two complementary thermal ion loss theories that explain most of the observed features, including a scaling with Ti. One theory considers passing and trapped particles that are lost via a loss cone purely due to drifts and the other considers turbulence-enhanced loss of passing particles. Work supported by the US DOE under DE-FC02-04ER54698, DE-FG02-07ER54917 and DE-AC02-09CH111466.

Investigation on heat transfer analysis and its effect on a multi-mode, beam-wave interaction for a 140 GHz, MW-class gyrotron

NASA Astrophysics Data System (ADS)

Liu, Qiao; Liu, Yinghui; Chen, Zhaowei; Niu, Xinjian; Li, Hongfu; Xu, Jianhua

2018-04-01

The interaction cavity of a 140 GHz, 1 MW continuous wave gyrotron developed in UESTC will be loaded with a very large heat load in the inner surface during operation. In order to reduce the heat, the axial wedge grooves of the outside surface of the cavity are considered and employed as the heat radiation structure. Thermoanalysis and structural analysis were discussed in detail to obtain the effects of heat on the cavity. In thermoanalysis, the external coolant-flow rates ranging from 20 L/min to 50 L/min were considered, and the distribution of wall loading was loaded as the heat flux source. In structural analysis, the cavity's deformation caused by the loads of heat and pressure was calculated. Compared with a non-deformed cavity, the effects of deformation on the performance of a cavity were discussed. For a cold-cavity, the results show that the quality factor would be reduced by 72, 89, 99 and 171 at the flow rates of 50 L/min, 40 L/min, 30 L/min and 20 L/min, respectively. Correspondingly, the cold-cavity frequencies would be decreased by 0.13 GHz, 0.15 GHz, 0.19 GHz and 0.38 GHz, respectively. For a hot-cavity, the results demonstrate that the output port frequencies would be dropped down, but the offset would be gradually decreased with increasing coolant-flow rate. Meanwhile, the output powers would be reduced dramatically with decreasing coolant-flow rate. In addition, when the coolant-flow rate reaches 40 L/min, the output power and the frequency are just reduced by 30 kW and 0.151 GHz, respectively.

Surface effects on friction-induced fluid heating in nanochannel flows.

PubMed

Li, Zhigang

2009-02-01

We investigate the mechanism of friction-induced fluid heating under the influence of surfaces. The temperature distributions of liquid argon and helium in nanoscale Poiseuille flows are studied through molecular dynamics simulations. It is found that the fluid heating is mainly caused by the viscous friction in the fluid when the external force is small and there is no slip at the fluid-solid interface. When the external force is larger than the fluid-surface binding force, the friction at the fluid-solid interface dominates over the internal friction of the fluid and is the major contribution to fluid heating. An asymmetric temperature gradient in the fluid is developed in the case of nonidentical walls and the general temperature gradient may change sign as the dominant heating factor changes from internal to interfacial friction with increasing external force. The effect of temperature on the fluid heating is also discussed.

CFD flowfield simulation of Delta Launch Vehicles in a power-on configuration

NASA Technical Reports Server (NTRS)

Pavish, D. L.; Gielda, T. P.; Soni, B. K.; Deese, J. E.; Agarwal, R. K.

1993-01-01

This paper summarizes recent work at McDonnell Douglas Aerospace (MDA) to develop and validate computational fluid dynamic (CFD) simulations of under expanded rocket plume external flowfields for multibody expendable launch vehicles (ELVs). Multi engine reacting gas flowfield predictions of ELV base pressures are needed to define vehicle base drag and base heating rates for sizing external nozzle and base region insulation thicknesses. Previous ELV design programs used expensive multibody power-on wind tunnel tests that employed chamber/nozzle injected high pressure cold or hot-air. Base heating and pressure measurements were belatedly made during the first flights of past ELV's to correct estimates from semi-empirical engineering models or scale model tests. Presently, CFD methods for use in ELV design are being jointly developed at the Space Transportation Division (MDA-STD) and New Aircraft Missiles Division (MDA-NAMD). An explicit three dimensional, zonal, finite-volume, full Navier-Stokes (FNS) solver with finite rate hydrocarbon/air and aluminum combustion kinetics was developed to accurately compute ELV power-on flowfields. Mississippi State University's GENIE++ general purpose interactive grid generation code was chosen to create zonal, finite volume viscous grids. Axisymmetric, time dependent, turbulent CFD simulations of a Delta DSV-2A vehicle with a MB-3 liquid main engine burning RJ-1/LOX were first completed. Hydrocarbon chemical kinetics and a k-epsilon turbulence model were employed and predictions were validated with flight measurements of base pressure and temperature. Zonal internal/external grids were created for a Delta DSV-2C vehicle with a MB-3 and three Castor-1 solid motors burning and a Delta-2 with an RS-27 main engine (LOX/RP-1) and 9 GEM's attached/6 burning. Cold air, time dependent FNS calculations were performed for DSV-2C during 1992. Single phase simulations that employ finite rate hydrocarbon and aluminum (solid fuel) combustion chemistry are currently in progress. Reliable and efficient Eulerian algorithms are needed to model two phase (solid-gas) momentum and energy transfer mechanisms for solid motor fuel combustion products.

CFD flowfield simulation of Delta Launch Vehicles in a power-on configuration

NASA Astrophysics Data System (ADS)

Pavish, D. L.; Gielda, T. P.; Soni, B. K.; Deese, J. E.; Agarwal, R. K.

1993-07-01

This paper summarizes recent work at McDonnell Douglas Aerospace (MDA) to develop and validate computational fluid dynamic (CFD) simulations of under expanded rocket plume external flowfields for multibody expendable launch vehicles (ELVs). Multi engine reacting gas flowfield predictions of ELV base pressures are needed to define vehicle base drag and base heating rates for sizing external nozzle and base region insulation thicknesses. Previous ELV design programs used expensive multibody power-on wind tunnel tests that employed chamber/nozzle injected high pressure cold or hot-air. Base heating and pressure measurements were belatedly made during the first flights of past ELV's to correct estimates from semi-empirical engineering models or scale model tests. Presently, CFD methods for use in ELV design are being jointly developed at the Space Transportation Division (MDA-STD) and New Aircraft Missiles Division (MDA-NAMD). An explicit three dimensional, zonal, finite-volume, full Navier-Stokes (FNS) solver with finite rate hydrocarbon/air and aluminum combustion kinetics was developed to accurately compute ELV power-on flowfields. Mississippi State University's GENIE++ general purpose interactive grid generation code was chosen to create zonal, finite volume viscous grids. Axisymmetric, time dependent, turbulent CFD simulations of a Delta DSV-2A vehicle with a MB-3 liquid main engine burning RJ-1/LOX were first completed. Hydrocarbon chemical kinetics and a k-epsilon turbulence model were employed and predictions were validated with flight measurements of base pressure and temperature. Zonal internal/external grids were created for a Delta DSV-2C vehicle with a MB-3 and three Castor-1 solid motors burning and a Delta-2 with an RS-27 main engine (LOX/RP-1) and 9 GEM's attached/6 burning. Cold air, time dependent FNS calculations were performed for DSV-2C during 1992. Single phase simulations that employ finite rate hydrocarbon and aluminum (solid fuel) combustion chemistry are currently in progress. Reliable and efficient Eulerian algorithms are needed to model two phase (solid-gas) momentum and energy transfer mechanisms for solid motor fuel combustion products.

Variable velocity in solar external receivers

NASA Astrophysics Data System (ADS)

Rodríguez-Sánchez, M. R.; Sánchez-González, A.; Acosta-Iborra, A.; Santana, D.

2017-06-01

One of the major problems in solar external receivers is tube overheating, which accelerates the risk of receiver failure. It can be solved implementing receivers with high number of panels. However, it exponentially increases the pressure drop in the receiver and the parasitic power consumption of the Solar Power Tower (SPT), reducing the global efficiency of the SPT. A new concept of solar external receiver, named variable velocity receiver, is able to adapt their configuration to the different flux density distributions. A set of valves allows splitting in several independent panels those panels in which the wall temperature is over the limit. It increases the velocity of the heat transfer fluid (HTF) and its cooling capacity. This receiver does not only reduce the wall temperature of the tubes, but also simplifies the control of the heliostat field and allows to employ more efficient aiming strategies. In this study, it has been shown that variable velocity receiver presents high advantages with respect to traditional receiver. Nevertheless, more than two divisions per panels are not recommendable, due to the increment of the pressure drop over 70 bars. In the design point (12 h of the Spring Equinox), the use of a variable number of panels between 18 and 36 (two divisions per panel), in a SPT similar to Gemasolar, improves the power capacity of the SPT in 5.7%, with a pressure drop increment of 10 bars. Off-design, when the flux distribution is high and not symmetric (e.g. 10-11 h), the power generated by the variable velocity receiver is 18% higher than the generated by the traditional receiver, at these hours the pressure drop increases almost 20 bars.

High performance 3-coil wireless power transfer system for the 512-electrode epiretinal prosthesis.

PubMed

Zhao, Yu; Nandra, Mandheerej; Yu, Chia-Chen; Tai, Yu-chong

2012-01-01

The next-generation retinal prostheses feature high image resolution and chronic implantation. These features demand the delivery of power as high as 100 mW to be wireless and efficient. A common solution is the 2-coil inductive power link, used by current retinal prostheses. This power link tends to include a larger-size extraocular receiver coil coupled to the external transmitter coil, and the receiver coil is connected to the intraocular electrodes through a trans-sclera trans-choroid cable. In the long-term implantation of the device, the cable may cause hypotony (low intraocular pressure) and infection. However, when a 2-coil system is constructed from a small-size intraocular receiver coil, the efficiency drops drastically which may induce over heat dissipation and electromagnetic field exposure. Our previous 2-coil system achieved only 7% power transfer. This paper presents a fully intraocular and highly efficient wireless power transfer system, by introducing another inductive coupling link to bypass the trans-sclera trans-choroid cable. With the specific equivalent load of our customized 512-electrode stimulator, the current 3-coil inductive link was measured to have the overall power transfer efficiency around 36%, with 1-inch separation in saline. The high efficiency will favorably reduce the heat dissipation and electromagnetic field exposure to surrounding human tissues. The effect of the eyeball rotation on the power transfer efficiency was investigated as well. The efficiency can still maintain 14.7% with left and right deflection of 30 degree during normal use. The surgical procedure for the coils' implantation into the porcine eye was also demonstrated.

A Magnetic Resonance Imaging-Conditional External Cardiac Defibrillator for Resuscitation Within the Magnetic Resonance Imaging Scanner Bore.

PubMed

Schmidt, Ehud J; Watkins, Ronald D; Zviman, Menekhem M; Guttman, Michael A; Wang, Wei; Halperin, Henry A

2016-10-01

Subjects undergoing cardiac arrest within a magnetic resonance imaging (MRI) scanner are currently removed from the bore and then from the MRI suite, before the delivery of cardiopulmonary resuscitation and defibrillation, potentially increasing the risk of mortality. This precludes many higher-risk (acute ischemic and acute stroke) patients from undergoing MRI and MRI-guided intervention. An MRI-conditional cardiac defibrillator should enable scanning with defibrillation pads attached and the generator ON, enabling application of defibrillation within the seconds of MRI after a cardiac event. An MRI-conditional external defibrillator may improve patient acceptance for MRI procedures. A commercial external defibrillator was rendered 1.5 Tesla MRI-conditional by the addition of novel radiofrequency filters between the generator and commercial disposable surface pads. The radiofrequency filters reduced emission into the MRI scanner and prevented cable/surface pad heating during imaging, while preserving all the defibrillator monitoring and delivery functions. Human volunteers were imaged using high specific absorption rate sequences to validate MRI image quality and lack of heating. Swine were electrically fibrillated (n=4) and thereafter defibrillated both outside and inside the MRI bore. MRI image quality was reduced by 0.8 or 1.6 dB, with the generator in monitoring mode and operating on battery or AC power, respectively. Commercial surface pads did not create artifacts deeper than 6 mm below the skin surface. Radiofrequency heating was within US Food and Drug Administration guidelines. Defibrillation was completely successful inside and outside the MRI bore. A prototype MRI-conditional defibrillation system successfully defibrillated in the MRI without degrading the image quality or increasing the time needed for defibrillation. It can increase patient acceptance for MRI procedures. © 2016 American Heart Association, Inc.

CFD Analysis for Assessing the Effect of Wind on the Thermal Control of the Mars Science Laboratory Curiosity Rover

NASA Technical Reports Server (NTRS)

Bhandari, Pradeep; Anderson, Kevin

2013-01-01

The challenging range of landing sites for which the Mars Science Laboratory Rover was designed, requires a rover thermal management system that is capable of keeping temperatures controlled across a wide variety of environmental conditions. On the Martian surface where temperatures can be as cold as -123 C and as warm as 38 C, the rover relies upon a Mechanically Pumped Fluid Loop (MPFL) Rover Heat Rejection System (RHRS) and external radiators to maintain the temperature of sensitive electronics and science instruments within a -40 C to 50 C range. The RHRS harnesses some of the waste heat generated from the rover power source, known as the Multi Mission Radioisotope Thermoelectric Generator (MMRTG), for use as survival heat for the rover during cold conditions. The MMRTG produces 110 W of electrical power while generating waste heat equivalent to approximately 2000 W. Heat exchanger plates (hot plates) positioned close to the MMRTG pick up this survival heat from it by radiative heat transfer. Winds on Mars can be as fast as 15 m/s for extended periods. They can lead to significant heat loss from the MMRTG and the hot plates due to convective heat pick up from these surfaces. Estimation of this convective heat loss cannot be accurately and adequately achieved by simple textbook based calculations because of the very complicated flow fields around these surfaces, which are a function of wind direction and speed. Accurate calculations necessitated the employment of sophisticated Computational Fluid Dynamics (CFD) computer codes. This paper describes the methodology and results of these CFD calculations. Additionally, these results are compared to simple textbook based calculations that served as benchmarks and sanity checks for them. And finally, the overall RHRS system performance predictions will be shared to show how these results affected the overall rover thermal performance.

Design, fabrication and testing of a CFA for use in the solar power satellite

NASA Technical Reports Server (NTRS)

Brown, W. C.

1978-01-01

A crossed field amplifier was designed to meet the performance objectives of high signal to noise ratio, an efficiency of 85%, a CW microwave power output of 5-8 kW, and a frequency of 2450 MHz. The signal to noise ratio achieved was better than 69 db/MHz in a 2000 MHz band centered on the carrier. High circuit efficiency of 97% and a sharp knee on voltage current characteristic were achieved. The basic problem of maintaining good transfer of heat to the external radiator while providing for adequate connections to input and output was solved. Maximum efficiency achieved was 70.5% and gain and power level were below objectives. An investigation of causes of reduced performance indicated the poor field pattern in the cathode anode interaction area of the tube was a major cause.

77 FR 22472 - Energy Conservation Program: Energy Conservation Standards for Certain External Power Supplies...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-16

... Conservation Program: Energy Conservation Standards for Certain External Power Supplies; Correction AGENCY... external power supplies to re-insert a table that had been inadvertently deleted by a technical amendment... standards for all Class A external power supplies to meet. DATES: This correction is effective April 16...

Design and Development of Micro-Power Generating Device for Biomedical Applications of Lab-on-a-Disc

PubMed Central

Joseph, Karunan; Ibrahim, Fatimah; Cho, Jongman; Thio, Tzer Hwai Gilbert; Al-Faqheri, Wisam; Madou, Marc

2015-01-01

The development of micro-power generators for centrifugal microfluidic discs enhances the platform as a green point-of-care diagnostic system and eliminates the need for attaching external peripherals to the disc. In this work, we present micro-power generators that harvest energy from the disc’s rotational movement to power biomedical applications on the disc. To implement these ideas, we developed two types of micro-power generators using piezoelectric films and an electromagnetic induction system. The piezoelectric-based generator takes advantage of the film’s vibration during the disc’s rotational motion, whereas the electromagnetic induction-based generator operates on the principle of current generation in stacks of coil exposed to varying magnetic flux. We have successfully demonstrated that at the spinning speed of 800 revolutions per minute (RPM) the piezoelectric film-based generator is able to produce up to 24 microwatts using 6 sets of films and the magnetic induction-based generator is capable of producing up to 125 milliwatts using 6 stacks of coil. As a proof of concept, a custom made localized heating system was constructed to test the capability of the magnetic induction-based generator. The heating system was able to achieve a temperature of 58.62°C at 2200 RPM. This development of lab-on-a-disc micro power generators preserves the portability standards and enhances the future biomedical applications of centrifugal microfluidic platforms. PMID:26422249

Improvement of water transport mechanisms during potato drying by applying ultrasound.

PubMed

Ozuna, César; Cárcel, Juan A; García-Pérez, José V; Mulet, Antonio

2011-11-01

The drying rate of vegetables is limited by internal moisture diffusion and convective transport mechanisms. The increase of drying air temperature leads to faster water mobility; however, it provokes quality loss in the product and presents a higher energy demand. Therefore, the search for new strategies to improve water mobility during convective drying constitutes a topic of relevant research. The aim of this work was to evaluate the use of power ultrasound to improve convective drying of potato and quantify the influence of the applied power in the water transport mechanisms. Drying kinetics of potato cubes were increased by the ultrasonic application. The influence of power ultrasound was dependent on the ultrasonic power (from 0 to 37 kW m(-3) ), the higher the applied power, the faster the drying kinetic. The diffusion model considering external resistance to mass transfer provided a good fit of drying kinetics. From modelling, it was observed a proportional and significant (P < 0.05) influence of the applied ultrasonic power on the identified kinetic parameters: effective moisture diffusivity and mass transfer coefficient. The ultrasonic application during drying represents an interesting alternative to traditional convective drying by shortening drying time, which may involve an energy saving concerning industrial applications. In addition, the ultrasonic effect in the water transport is based on mechanical phenomena with a low heating capacity, which is highly relevant for drying heat sensitive materials and also for obtaining high-quality dry products. Copyright © 2011 Society of Chemical Industry.

Unsteady Stored Heat Behavior in Building Frame of Reinforced Concrete Structure Type Cold Storage

NASA Astrophysics Data System (ADS)

Nomura, Tomohiro; Murakami, Yuji; Uchikawa, Motoyuki

The time variation of temperature in the reinforced concrete frame with an internal insulation or with an external insulation and the unsteady stored heat behavior, which results from the thermal mass of the concrete frame, have been investigated. The experiments with the concrete models and the measurements of the heat flux through the practical cold storage were performed. The experimental results under the unsteady condition showed great difference of the stored heat behavior between the internal insulation type and the external type. In addition, it was shown that the external insulation frame was useful for heat storage. The simulation method with two dimentional unsteady FEM was introduced for easily analyzing the stored heat behavior problems of the practical cold storages, which had various specifications in design. The calculated results of the heat flux and temperature in the concrete frame agreed with the experiments approximately. From these results, the suggestions for the design of the insulation wall under the unsteady condition were given.

Thermophysical fundamentals of cyclonic recirculating heating devices

NASA Astrophysics Data System (ADS)

Karpov, S. V.; Zagoskin, A. A.

2017-10-01

This report presents the results of experimental and theoretical research of aerodynamics and convective heat transfer in cyclone devices with the new system of external recirculation of heating gas under the influence of radial pressure gradient in a heat carrier’s swirling turbulent flow. The dynamic problem of tangential velocity distribution in a clearance volume is solved at various re-circulation ratio values including limiting quantities (kr = 0; 1) and variations in cyclonic combustion chamber’s design parameters and operating conditions (Rer); the integrated calculation ratios for fundamental aerodynamic characteristics of a recirculation device are derived. The first experimental and numerical studies of convective heat transfer on internal and external surfaces of a hollow shaft in a swirling recirculation flow are derived through the instrumentality of OpenFOAM, these studies are also conducted for a setting of several cylindrical solid inserts. The external surface heat problem of a hollow cylindrical insert is solved with integral and digital methods; generalized similarity equations for the internal and external surfaces extended in range of Reynolds number are derived. The experimental data is in reasonable agreement with the derived curves and the results of mathematic modelling of convective heat transfer. Calculation recommendations for optimal selection of kr values at various ratios of their geometric characteristics and products utilization rate are obtained.

TQUID Magnetometer and Artificial Neural Circuitry Based on a Topological Kondo Insulator

DTIC Science & Technology

2016-05-01

phenomena in this surface-bulk system. Sufficient Joule heating , induced by an external DC current, can heat the bulk into a less insulating state, and...are the surface and bulk resistances with insulating gap Δ; H = H0(/0)3 and are the heat capacity dominated by phonons and...0, while Δ is the energy gap in the insulating bulk; is the temperature independent heat transfer rate trough external leads, which plays the

Long pulse operation of the Kamaboko negative ion source on the MANTIS test bed

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

Tramham, R.; Jacquot, C.; Riz, D.

1998-08-20

Advanced Tokamak concepts and steady state plasma scenarios require external plasma heating and current drive for extended time periods. This poses several problems for the neutral beam injection systems that are currently in use. The power loading of the ion source and accelerator are especially problematic. The Kamaboko negative ion source, a small scale model of the ITER arc source, is being prepared for extended operation of deuterium beams for up to 1000 seconds. The operating conditions of the plasma grid prove to be important for reducing electron power loading of the accelerator. Operation of deuterium beams for extended periodsmore » also poses radiation safety risks which must be addressed.« less

NEXT Ion Thruster Thermal Model

NASA Technical Reports Server (NTRS)

VanNoord, Jonathan L.

2010-01-01

As the NEXT ion thruster progresses towards higher technology readiness, it is necessary to develop the tools that will support its implementation into flight programs. An ion thruster thermal model has been developed for the latest prototype model design to aid in predicting thruster temperatures for various missions. This model is comprised of two parts. The first part predicts the heating from the discharge plasma for various throttling points based on a discharge chamber plasma model. This model shows, as expected, that the internal heating is strongly correlated with the discharge power. Typically, the internal plasma heating increases with beam current and decreases slightly with beam voltage. The second is a model based on a finite difference thermal code used to predict the thruster temperatures. Both parts of the model will be described in this paper. This model has been correlated with a thermal development test on the NEXT Prototype Model 1 thruster with most predicted component temperatures within 5 to 10 C of test temperatures. The model indicates that heating, and hence current collection, is not based purely on the footprint of the magnet rings, but follows a 0.1:1:2:1 ratio for the cathode-to-conical-to-cylindrical-to-front magnet rings. This thermal model has also been used to predict the temperatures during the worst case mission profile that is anticipated for the thruster. The model predicts ample thermal margin for all of its components except the external cable harness under the hottest anticipated mission scenario. The external cable harness will be re-rated or replaced to meet the predicted environment.

Regionally dependent summer heat wave response to increased surface temperature in the US

NASA Astrophysics Data System (ADS)

Lopez, H.; Dong, S.; Kirtman, B. P.; Goni, G. J.; Lee, S. K.; Atlas, R. M.; West, R.

2017-12-01

Climate projections for the 21st Century suggest an increase in the occurrence of heat waves. However, the time it takes for the externally forced signal of climate change to emerge against the background of natural variability (i.e., Time of Emergence, ToE) particularly on the regional scale makes reliable future projection of heat waves challenging. Here, we combine observations and model simulations under present and future climate forcing to assess internal variability versus external forcing in modulating US heat waves. We characterized the most common heat wave patterns over the US by the use of clustering of extreme events by their spatial distribution. For each heat wave cluster, we assess changes in the probability density function (PDF) of summer temperature extremes by modeling the PDF as a stochastically generated skewed (SGS) distribution. The probability of necessary causation for each heat wave cluster was also quantified, allowing to make assessments of heat extreme attribution to anthropogenic climate change. The results suggest that internal variability will dominate heat wave occurrence over the Great Plains with ToE occurring in the 2050s (2070s) and of occurrence of ratio of warm-to-cold extremes of 1.7 (1.7) for the Northern (Southern) Plains. In contrast, external forcing will dominate over the Western (Great Lakes) region with ToE occurring as early as in the 2020s (2030s) and warm-to-cold extremes ratio of 6.4 (10.2), suggesting caution in attributing heat extremes to external forcing due to their regional dependence.

TEM Pump With External Heat Source And Sink

NASA Technical Reports Server (NTRS)

Nesmith, Bill J.

1991-01-01

Proposed thermoelectric/electromagnetic (TEM) pump driven by external source of heat and by two or more heat pipe radiator heat sink(s). Thermoelectrics generate electrical current to circulate liquid metal in secondary loop of two-fluid-loop system. Intended for use with space and terrestrial dual loop liquid metal nuclear reactors. Applications include spacecraft on long missions or terrestrial beacons or scientific instruments having to operate in remote areas for long times. Design modified to include multiple radiators, converters, and ducts, as dictated by particular application.

Enhanced green fluorescent protein in optofluidic Fabry-Perot microcavity to detect laser induced temperature changes in a bacterial culture

NASA Astrophysics Data System (ADS)

Lahoz, F.; Martín, I. R.; Walo, D.; Freire, R.; Gil-Rostra, J.; Yubero, F.; Gonzalez-Elipe, A. R.

2017-09-01

Thermal therapy using laser sources can be used in combination with other cancer therapies to eliminate tumors. However, high precision temperature control is required to avoid damage in healthy surrounding tissues. Therefore, in order to detect laser induced temperature changes, we have used the fluorescence signal of the enhanced Green Fluorescent Protein (eGFP) over-expressed in an E. coli bacterial culture. For that purpose, the bacteria expressing eGFP are injected in a Fabry-Perot (FP) optofluidic planar microcavity. In order to locally heat the bacterial culture, external infrared or ultraviolet lasers were used. Shifts in the wavelengths of the resonant FP modes are used to determine the temperature increase as a function of the heating laser pump power. Laser induced local temperature increments up to 6-7 °C were measured. These results show a relatively easy way to measure laser induced local temperature changes using a FP microcavity and using eGFP as a molecular probe instead of external nanoparticles, which could damage/alter the cell. Therefore, we believe that this approach can be of interest for the study of thermal effects in laser induced thermal therapies.

Analysis of pipeline transportation systems for carbon dioxide sequestration

NASA Astrophysics Data System (ADS)

Witkowski, Andrzej; Majkut, Mirosław; Rulik, Sebastian

2014-03-01

A commercially available ASPEN PLUS simulation using a pipe model was employed to determine the maximum safe pipeline distances to subsequent booster stations as a function of carbon dioxide (CO2) inlet pressure, ambient temperature and ground level heat flux parameters under three conditions: isothermal, adiabatic and with account of heat transfer. In the paper, the CO2 working area was assumed to be either in the liquid or in the supercritical state and results for these two states were compared. The following power station data were used: a 900 MW pulverized coal-fired power plant with 90% of CO2 recovered (156.43 kg/s) and the monothanolamine absorption method for separating CO2 from flue gases. The results show that a subcooled liquid transport maximizes energy efficiency and minimizes the cost of CO2 transport over long distances under isothermal, adiabatic and heat transfer conditions. After CO2 is compressed and boosted to above 9 MPa, its temperature is usually higher than ambient temperature. The thermal insulation layer slows down the CO2 temperature decrease process, increasing the pressure drop in the pipeline. Therefore in Poland, considering the atmospheric conditions, the thermal insulation layer should not be laid on the external surface of the pipeline.

Situ soil sampling probe system with heated transfer line

DOEpatents

Robbat, Jr., Albert

2002-01-01

The present invention is directed both to an improved in situ penetrometer probe and to a heated, flexible transfer line. The line and probe may be implemented together in a penetrometer system in which the transfer line is used to connect the probe to a collector/analyzer at the surface. The probe comprises a heater that controls a temperature of a geologic medium surrounding the probe. At least one carrier gas port and vapor collection port are located on an external side wall of the probe. The carrier gas port provides a carrier gas into the geologic medium, and the collection port captures vapors from the geologic medium for analysis. In the transfer line, a flexible collection line that conveys a collected fluid, i.e., vapor, sample to a collector/analyzer. A flexible carrier gas line conveys a carrier gas to facilitate the collection of the sample. A system heating the collection line is also provided. Preferably the collection line is electrically conductive so that an electrical power source can generate a current through it so that the internal resistance generates heat.

Conceptual design of a lunar base thermal control system

NASA Technical Reports Server (NTRS)

Simonsen, Lisa C.; Debarro, Marc J.; Farmer, Jeffery T.

1992-01-01

Space station and alternate thermal control technologies were evaluated for lunar base applications. The space station technologies consisted of single-phase, pumped water loops for sensible and latent heat removal from the cabin internal environment and two-phase ammonia loops for the transportation and rejection of these heat loads to the external environment. Alternate technologies were identified for those areas where space station technologies proved to be incompatible with the lunar environment. Areas were also identified where lunar resources could enhance the thermal control system. The internal acquisition subsystem essentially remained the same, while modifications were needed for the transport and rejection subsystems because of the extreme temperature variations on the lunar surface. The alternate technologies examined to accommodate the high daytime temperatures incorporated lunar surface insulating blankets, heat pump system, shading, and lunar soil. Other heat management techniques, such as louvers, were examined to prevent the radiators from freezing. The impact of the geographic location of the lunar base and the orientation of the radiators was also examined. A baseline design was generated that included weight, power, and volume estimates.

Fire behavior of halogen-free flame retardant electrical cables with the cone calorimeter.

PubMed

Meinier, Romain; Sonnier, Rodolphe; Zavaleta, Pascal; Suard, Sylvain; Ferry, Laurent

2018-01-15

Fires involving electrical cables are one of the main hazards in Nuclear Power Plants (NPPs). Cables are complex assemblies including several polymeric parts (insulation, bedding, sheath) constituting fuel sources. This study provides an in-depth characterization of the fire behavior of two halogen-free flame retardant cables used in NPPs using the cone calorimeter. The influence of two key parameters, namely the external heat flux and the spacing between cables, on the cable fire characteristics is especially investigated. The prominent role of the outer sheath material on the ignition and the burning at early times was highlighted. A parameter of utmost importance called transition heat flux, was identified and depends on the composition and the structure of the cable. Below this heat flux, the decomposition is limited and concerns only the sheath. Above it, fire hazard is greatly enhanced because most often non-flame retarded insulation part contributes to heat release. The influence of spacing appears complex, and depends on the considered fire property. Copyright © 2017 Elsevier B.V. All rights reserved.

Dielectric Heaters for Testing Spacecraft Nuclear Reactors

NASA Technical Reports Server (NTRS)

Sims, William Herbert; Bitteker, Leo; Godfroy, Thomas

2006-01-01

A document proposes the development of radio-frequency-(RF)-driven dielectric heaters for non-nuclear thermal testing of the cores of nuclear-fission reactors for spacecraft. Like the electrical-resistance heaters used heretofore for such testing, the dielectric heaters would be inserted in the reactors in place of nuclear fuel rods. A typical heater according to the proposal would consist of a rod of lossy dielectric material sized and shaped like a fuel rod and containing an electrically conductive rod along its center line. Exploiting the dielectric loss mechanism that is usually considered a nuisance in other applications, an RF signal, typically at a frequency .50 MHz and an amplitude between 2 and 5 kV, would be applied to the central conductor to heat the dielectric material. The main advantage of the proposal is that the wiring needed for the RF dielectric heating would be simpler and easier to fabricate than is the wiring needed for resistance heating. In some applications, it might be possible to eliminate all heater wiring and, instead, beam the RF heating power into the dielectric rods from external antennas.

Numerical modeling of the thermoelectric cooler with a complementary equation for heat circulation in air gaps

NASA Astrophysics Data System (ADS)

Fang, En; Wu, Xiaojie; Yu, Yuesen; Xiu, Junrui

2017-03-01

In this paper, a numerical model is developed by combining thermodynamics with heat transfer theory. Taking inner and external multi-irreversibility into account, it is with a complementary equation for heat circulation in air gaps of a steady cooling system with commercial thermoelectric modules operating in refrigeration mode. With two modes concerned, the equation presents the heat flowing through air gaps which forms heat circulations between both sides of thermoelectric coolers (TECs). In numerical modelling, a TEC is separated as two temperature controlled constant heat flux reservoirs in a thermal resistance network. In order to obtain the parameter values, an experimental apparatus with a commercial thermoelectric cooler was built to characterize the performance of a TEC with heat source and sink assembly. At constant power dissipation, steady temperatures of heat source and both sides of the thermoelectric cooler were compared with those in a standard numerical model. The method displayed that the relationship between Φf and the ratio Φ_{c}'/Φ_{c} was linear as expected. Then, for verifying the accuracy of proposed numerical model, the data in another system were recorded. It is evident that the experimental results are in good agreement with simulation(proposed model) data at different heat transfer rates. The error is small and mainly results from the instabilities of thermal resistances with temperature change and heat flux, heat loss of the device vertical surfaces and measurements.

Jumping-droplet electronics hot-spot cooling

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

Oh, Junho; Birbarah, Patrick; Foulkes, Thomas

Demand for enhanced cooling technologies within various commercial and consumer applications has increased in recent decades due to electronic devices becoming more energy dense. This study demonstrates jumping-droplet based electric-field-enhanced (EFE) condensation as a potential method to achieve active hot spot cooling in electronic devices. To test the viability of EFE condensation, we developed an experimental setup to remove heat via droplet evaporation from single and multiple high power gallium nitride (GaN) transistors acting as local hot spots (4.6 mm x 2.6 mm). An externally powered circuit was developed to direct jumping droplets from a copper oxide (CuO) nanostructured superhydrophobicmore » surface to the transistor hot spots by applying electric fields between the condensing surface and the transistor. Heat transfer measurements were performed in ambient air (22-25°C air temperature, 20-45% relative humidity) to determine the effect of gap spacing (2-4 mm), electric field (50-250 V/cm), and heat flux (demonstrated to 13 W/cm 2). EFE condensation was shown to enhance the heat transfer from the local hot spot by ≈ 200% compared to cooling without jumping and by 20% compared to non-EFE jumping. Dynamic switching of the electric field for a two-GaN system reveals the potential for active cooling of mobile hot spots. The opportunity for further cooling enhancement by the removal of non-condensable gases promises hot spot heat dissipation rates approaching 120 W/cm 2. Finally, this work provides a framework for the development of active jumping droplet based vapor chambers and heat pipes capable of spatial and temporal thermal dissipation control.« less

Jumping-droplet electronics hot-spot cooling

DOE PAGES

Oh, Junho; Birbarah, Patrick; Foulkes, Thomas; ...

2017-03-20

Demand for enhanced cooling technologies within various commercial and consumer applications has increased in recent decades due to electronic devices becoming more energy dense. This study demonstrates jumping-droplet based electric-field-enhanced (EFE) condensation as a potential method to achieve active hot spot cooling in electronic devices. To test the viability of EFE condensation, we developed an experimental setup to remove heat via droplet evaporation from single and multiple high power gallium nitride (GaN) transistors acting as local hot spots (4.6 mm x 2.6 mm). An externally powered circuit was developed to direct jumping droplets from a copper oxide (CuO) nanostructured superhydrophobicmore » surface to the transistor hot spots by applying electric fields between the condensing surface and the transistor. Heat transfer measurements were performed in ambient air (22-25°C air temperature, 20-45% relative humidity) to determine the effect of gap spacing (2-4 mm), electric field (50-250 V/cm), and heat flux (demonstrated to 13 W/cm 2). EFE condensation was shown to enhance the heat transfer from the local hot spot by ≈ 200% compared to cooling without jumping and by 20% compared to non-EFE jumping. Dynamic switching of the electric field for a two-GaN system reveals the potential for active cooling of mobile hot spots. The opportunity for further cooling enhancement by the removal of non-condensable gases promises hot spot heat dissipation rates approaching 120 W/cm 2. Finally, this work provides a framework for the development of active jumping droplet based vapor chambers and heat pipes capable of spatial and temporal thermal dissipation control.« less

Effect of External Loading on Force and Power Production During Plyometric Push-ups.

PubMed

Hinshaw, Taylour J; Stephenson, Mitchell L; Sha, Zhanxin; Dai, Boyi

2018-04-01

Hinshaw, TJ, Stephenson, ML, Sha, Z, and Dai, B. Effect of external loading on force and power production during plyometric push-ups. J Strength Cond Res 32(4): 1099-1108, 2018-One common exercise to train upper-body strength and power is the push-up. Training at the loads that would produce the greatest power is an effective way to increase peak power. The purpose of the current study was to quantify the changes in peak force, peak power, and peak velocity among a modified plyometric push-up and plyometric push-ups with or without external loading in physically active young adults. Eighteen male and 17 female participants completed 4 push-ups: (a) modified plyometric push-up on the knees, (b) plyometric push-up without external loading, (c) plyometric push-up with an external load of 5% of body weight, and (d) plyometric push-up with an external load of 10% of body weight. Two force platforms were set up to collect vertical ground reaction forces at the hands and feet. The modified plyometric push-up demonstrated the lowest force, power, and velocity (5.4≥ Cohen's dz ≥1.2). Peak force and force at peak velocity increased (3.8≥ Cohen's dz ≥0.3) and peak velocity and velocity at peak power decreased (1.4≥ Cohen's dz ≥0.8) for the push-up without external loading compared with the 2 push-ups with external loading. No significant differences were observed for peak power among the push-ups with or without external loading (0.4≥ Cohen's dz ≥0.1). Although peak power is similar with or without external loading, push-ups without external loading may be more beneficial for a quick movement, and push-ups with external loading may be more beneficial for a greater force production.

10 CFR Appendix Z to Subpart B of... - Uniform Test Method for Measuring the Energy Consumption of External Power Supplies

Code of Federal Regulations, 2012 CFR

2012-01-01

... operation when the external power supply is connected to the main electricity supply and the output is (or... external power supply is connected to the main electricity supply and the output is (or “all outputs are... switches, in which the external power supply is (1) connected to the main electricity supply; (2) the...

10 CFR Appendix Z to Subpart B of... - Uniform Test Method for Measuring the Energy Consumption of External Power Supplies

Code of Federal Regulations, 2013 CFR

2013-01-01

... operation when the external power supply is connected to the main electricity supply and the output is (or... external power supply is connected to the main electricity supply and the output is (or “all outputs are... switches, in which the external power supply is (1) connected to the main electricity supply; (2) the...

10 CFR Appendix Z to Subpart B of... - Uniform Test Method for Measuring the Energy Consumption of External Power Supplies

Code of Federal Regulations, 2014 CFR

2014-01-01

... operation when the external power supply is connected to the main electricity supply and the output is (or... external power supply is connected to the main electricity supply and the output is (or “all outputs are... switches, in which the external power supply is (1) connected to the main electricity supply; (2) the...

Cervical external immobilization devices: evaluation of magnetic resonance imaging issues at 3.0 Tesla.

PubMed

Diaz, Francis L; Tweardy, Lisa; Shellock, Frank G

2010-02-15

Laboratory investigation, ex vivo. Currently, no studies have addressed the magnetic resonance imaging (MRI) issues for cervical external immobilization devices at 3-Tesla. Under certain conditions significant heating may occur, resulting in patient burns. Furthermore, artifacts can be substantial and prevent the diagnostic use of MRI. Therefore, the objective of this investigation was to evaluate MRI issues for 4 different cervical external immobilization devices at 3-Tesla. Excessive heating and substantial artifacts are 2 potential complications associated with performing MRI at 3-Tesla in patients with cervical external immobilization devices. Using ex vivo testing techniques, MRI-related heating and artifacts were evaluated for 4 different cervical devices during MRI at 3-Tesla. Four cervical external immobilization devices (Generation 80, Resolve Ring and Superstructure, Resolve Ring and Jerome Vest/Jerome Superstructure, and the V1 Halo System; Ossur Americas, Aliso Viejo, CA) underwent MRI testing at 3-Tesla. All devices were made from nonmetallic or nonmagnetic materials. Heating was determined using a gelled-saline-filled skull phantom with fluoroptic thermometry probes attached to the skull pins. MRI was performed at 3-Tesla, using a high level of RF energy. Artifacts were assessed at 3-Tesla, using standard cervical imaging techniques. The Generation 80 and V1 Halo devices exhibited substantial temperature rises (11.6 degrees C and 8.5 degrees C, respectively), with "sparking" evident for the Generation 80 during the MRI procedure. Artifacts were problematic for these devices, as well. By comparison, the 2 Resolve Ring-based cervical external immobilization devices showed little or no heating (< or = 0.6 degrees C) and the artifacts were acceptable for diagnostic MRI examinations. The low degree of heating and minor artifacts associated with the Resolve-based cervical external immobilization devices indicated that these products are safe for patients undergoing MRI at 3-Tesla.

Self-Powered Nanocomposites under an External Rotating Magnetic Field for Noninvasive External Power Supply Electrical Stimulation.

PubMed

Wu, Fengluan; Jin, Long; Zheng, Xiaotong; Yan, Bingyun; Tang, Pandeng; Yang, Huikai; Deng, Weili; Yang, Weiqing

2017-11-08

Electrical stimulation in biology and gene expression has attracted considerable attention in recent years. However, it is inconvenient that the electric stimulation needs to be supplied an implanted power-transported wire connecting the external power supply. Here, we fabricated a self-powered composite nanofiber (CNF) and developed an electric generating system to realize electrical stimulation based on the electromagnetic induction effect under an external rotating magnetic field. The self-powered CNFs generating an electric signal consist of modified MWNTs (m-MWNTs) coated Fe 3 O 4 /PCL fibers. Moreover, the output current of the nanocomposites can be increased due to the presence of the magnetic nanoparticles during an external magnetic field is applied. In this paper, these CNFs were employed to replace a bullfrog's sciatic nerve and to realize the effective functional electrical stimulation. The cytotoxicity assays and animal tests of the nanocomposites were also used to evaluate the biocompatibility and tissue integration. These results demonstrated that this self-powered CNF not only plays a role as power source but also can act as an external power supply under an external rotating magnetic field for noninvasive the replacement of injured nerve.

3-Dimensional numerical study of cooling performance of a heat sink with air-water flow through mini-channel

NASA Astrophysics Data System (ADS)

Majumder, Sambit; Majumder, Abhik; Bhaumik, Swapan

2016-07-01

The present microelectronics market demands devices with high power dissipation capabilities having enhanced cooling per unit area. The drive for miniaturizing the devices to even micro level dimensions is shooting up the applied heat flux on such devices, resulting in complexity in heat transfer and cooling management. In this paper, a method of CPU processor cooling is introduced where active and passive cooling techniques are incorporated simultaneously. A heat sink consisting of fins is designed, where water flows internally through the mini-channel fins and air flows externally. Three dimensional numerical simulations are performed for large set of Reynolds number in laminar region using finite volume method for both developing flows. The dimensions of mini-channel fins are varied for several aspect ratios such as 1, 1.33, 2 and 4. Constant temperature (T) boundary condition is applied at heat sink base. Channel fluid temperature, pressure drop are analyzed to obtain best cooling option in the present study. It has been observed that as the aspect ratio of the channel decreases Nusselt number decreases while pressure drop increases. However, Nusselt number increases with increase in Reynolds number.

Study of radioisotope safety devices for electric propulsion system, Volume 1: Summary report

NASA Technical Reports Server (NTRS)

Bradshaw, G. B.; Homeyer, W. G.; Postula, F. D.; Steeger, E. J.

1972-01-01

A new reference design was prepared for the 5 kW(e) thermionic power supply. The safety equipment in this design is a passive containment system which does not rely on the operation of any mechanisms such as a launch escape rocket or deployment of parachutes. It includes: (1) a blast shield to protect against the explosion of the launch vehicle; (2) a combination of refractory thermal insulation and heat storage material to protect against a sustained launch pad fire; (3) a reentry body with a spherical nose and a large conical flare at the aft end to stabilize the reentry attitude and lower the terminal velocity in air; (4) composite graphite thermal protection to sustain the reentry heat pulse; (5) crushable honeycomb behind the nose to limit the deceleration of the radioisotope source due to impact on land at terminal velocity; (6) a double-walled secondary containment vessel surrounding the isotopic capsules; (7) neutron shielding to reduce external dose rates; (8) an auxiliary cooling system employing redundant heat pipes to remove the radioactive decay heat from the heat source and reject it to the surroundings or to a forced convection loop.

Planform structure and heat transfer in turbulent free convection over horizontal surfaces

NASA Astrophysics Data System (ADS)

Theerthan, S. Ananda; Arakeri, Jaywant H.

2000-04-01

This paper deals with turbulent free convection in a horizontal fluid layer above a heated surface. Experiments have been carried out on a heated surface to obtain and analyze the planform structure and the heat transfer under different conditions. Water is the working fluid and the range of flux Rayleigh numbers (Ra) covered is 3×107-2×1010. The different conditions correspond to Rayleigh-Bénard convection, convection with either the top water surface open to atmosphere or covered with an insulating plate, and with an imposed external flow on the heated boundary. Without the external flow the planform is one of randomly oriented line plumes. At large Rayleigh number Ra and small aspect ratio (AR), these line plumes seem to align along the diagonal, presumably due to a large scale flow. The side views show inclined dyelines, again indicating a large scale flow. When the external flow is imposed, the line plumes clearly align in the direction of external flow. The nondimensional average plume spacing, Raλ1/3, varies between 40 and 90. The heat transfer rate, for all the experiments conducted, represented as RaδT-1/3, where δT is the conduction layer thickness, varies only between 0.1-0.2, showing that in turbulent convection the heat transfer rates are similar under the different conditions.

Effects of aqueous humor hydrodynamics on human eye heat transfer under external heat sources.

PubMed

Tiang, Kor L; Ooi, Ean H

2016-08-01

The majority of the eye models developed in the late 90s and early 00s considers only heat conduction inside the eye. This assumption is not entirely correct, since the anterior and posterior chambers are filled aqueous humor (AH) that is constantly in motion due to thermally-induced buoyancy. In this paper, a three-dimensional model of the human eye is developed to investigate the effects AH hydrodynamics have on the human eye temperature under exposure to external heat sources. If the effects of AH flow are negligible, then future models can be developed without taking them into account, thus simplifying the modeling process. Two types of external thermal loads are considered; volumetric and surface irradiation. Results showed that heat convection due to AH flow contributes to nearly 95% of the total heat flow inside the anterior chamber. Moreover, the circulation inside the anterior chamber can cause an upward shift of the location of hotspot. This can have significant consequences to our understanding of heat-induced cataractogenesis. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

Optimal Design of Biomass Utilization System for Rural Area Includes Technical and Economic Dimensions

NASA Astrophysics Data System (ADS)

Morioka, Yasuki; Nakata, Toshihiko

In order to design optimal biomass utilization system for rural area, OMNIBUS (The Optimization Model for Neo-Integrated Biomass Utilization System) has been developed. OMNIBUS can derive the optimal system configuration to meet different objective function, such as current account balance, amount of biomass energy supply, and CO2 emission. Most of biomass resources in a focused region e.g. wood biomass, livestock biomass, and crop residues are considered in the model. Conversion technologies considered are energy utilization technologies e.g. direct combustion and methane fermentation, and material utilization technologies e.g. composting and carbonization. Case study in Miyakojima, Okinawa prefecture, has been carried out for several objective functions and constraint conditions. Considering economics of the utilization system as a priority requirement, composting and combustion heat utilization are mainly chosen in the optimal system configuration. However gasification power plant and methane fermentation are included in optimal solutions, only when both biomass energy utilization and CO2 reduction have been set as higher priorities. External benefit of CO2 reduction has large impacts on the system configuration. Provided marginal external benefit of more than 50,000 JPY/t-C, external benefit becomes greater than the revenue from electricity and compost etc. Considering technological learning in the future, expensive technologies such as gasification power plant and methane fermentation will have economic feasibility as well as market competitiveness.

Using the sound of nuclear energy

DOE PAGES

Garrett, Steven; Smith, James; Smith, Robert; ...

2016-08-01

The generation of sound by heat has been documented as an “acoustical curiosity” since a Buddhist monk reported the loud tone generated by a ceremonial rice-cooker in his diary, in 1568. Over the last four decades, significant progress has been made in understanding “thermoacoustic processes,” enabling the design of thermoacoustic engines and refrigerators. Motivated by the Fukushima nuclear reactor disaster, we have developed and tested a thermoacoustic engine that exploits the energy-rich conditions in the core of a nuclear reactor to provide core condition information to the operators without a need for external electrical power. The heat engine is self-poweredmore » and can wirelessly transmit the temperature and reactor power level by generation of a pure tone which can be detected outside the reactor. We report here the first use of a fission-powered thermoacoustic engine capable of serving as a performance and safety sensor in the core of a research reactor and present data from the hydrophones in the coolant (far from the core) and an accelerometer attached to a structure outside the reactor. These measurements confirmed that the frequency of the sound produced indicates the reactor’s coolant temperature and that the amplitude (above an onset threshold) is related to the reactor’s operating power level. Furthermore, these signals can be detected even in the presence of substantial background noise generated by the reactor’s fluid pumps.« less

Using the sound of nuclear energy

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

Garrett, Steven; Smith, James; Smith, Robert

The generation of sound by heat has been documented as an “acoustical curiosity” since a Buddhist monk reported the loud tone generated by a ceremonial rice-cooker in his diary, in 1568. Over the last four decades, significant progress has been made in understanding “thermoacoustic processes,” enabling the design of thermoacoustic engines and refrigerators. Motivated by the Fukushima nuclear reactor disaster, we have developed and tested a thermoacoustic engine that exploits the energy-rich conditions in the core of a nuclear reactor to provide core condition information to the operators without a need for external electrical power. The heat engine is self-poweredmore » and can wirelessly transmit the temperature and reactor power level by generation of a pure tone which can be detected outside the reactor. We report here the first use of a fission-powered thermoacoustic engine capable of serving as a performance and safety sensor in the core of a research reactor and present data from the hydrophones in the coolant (far from the core) and an accelerometer attached to a structure outside the reactor. These measurements confirmed that the frequency of the sound produced indicates the reactor’s coolant temperature and that the amplitude (above an onset threshold) is related to the reactor’s operating power level. Furthermore, these signals can be detected even in the presence of substantial background noise generated by the reactor’s fluid pumps.« less

Solar tower enhanced natural draft dry cooling tower

NASA Astrophysics Data System (ADS)

Yang, Huiqiang; Xu, Yan; Acosta-Iborra, Alberto; Santana, Domingo

2017-06-01

Concentrating Solar Power (CSP) plants are located in desert areas where the Direct Normal Irradiance (DNI) value is very high. Since water resource is scarcely available, mechanical draft cooing technology is commonly used, with power consumption of mechanical fans being approximately 2% of the total power generated. Today, there is only one solar power plant (Khi Solar One in South Africa) uses a condenser installed in a Natural Draft Cooling (NDC) tower that avoids the windage loss of water occurring in wet cooling towers. Although, Khi Solar One is a cavity receiver power tower, the receivers can be hung onto the NDC tower. This paper looks at a novel integration of a NDC tower into an external molten salt receiver of a solar power plant, which is one of a largest commercial molten salt tower in China, with 100MWe power capacity. In this configuration study, the NDC tower surrounds the concrete tower of the receiver concentrically. In this way, the receiver concrete tower is the central support of the NDC tower, which consists of cable networks that are fixed to the concrete tower and suspended at a certain height over the floor. The cable networks support the shell of the NDC tower. To perform a preliminary analysis of the behavior of this novel configuration, two cases of numerical simulation in three dimensional (3D) models have been solved using the commercial Computational Fluid Dynamics (CFD) code, ANSYS Fluent 6.3. The results show that the integration of the NDC tower into an external central receiver tower is feasible. Additionally, the total heat transfer rate is not reduced but slightly increases when the molten salt receiver is in operation because of the additional natural draft induced by the high temperature of the receiver.

Heat transfer tests of a 0.006-scale thin skin space shuttle model (50-0, 41-T) in the Langley Research Center nitrogen tunnel at Mach 19 (IH19)

NASA Technical Reports Server (NTRS)

Walstad, D. G.

1975-01-01

Data are presented from heat transfer tests on an 0.0006-scale space shuttle vehicle in the Langley Research Center Nitrogen Tunnel. The purpose of this test was to obtain ascent heating data at a high hypersonic Mach number. Configurations tested were integrated orbiter and external tank, orbiter alone, and external tank alone. All configurations were tested with and without boundary layer transition. Testing was conducted at a Mach number of 19, a Reynolds number of 0.5 million per foot, and angles of attack of 0, + or - 5, and + or - 10 degrees. Heat transfer data was obtained from 77 orbiter and 90 external tank iron-constantan thermocouples.

Controlling thermal properties of dense gas fluidized beds for concentrated solar power by internal and external solids circulation

NASA Astrophysics Data System (ADS)

Ammendola, Paola; Bareschino, Piero; Chirone, Riccardo; Salatino, Piero; Solimene, Roberto

2017-06-01

Fluidization technology displays a long record of success stories, mostly related to applications to thermal and thermochemical processes, which are fostering extension to novel and relatively unexplored fields. Application of fluidized beds to collection and thermal storage of solar radiation in Concentrated Solar Power (CSP) is one of the most promising, a field which poses challenging issues and great opportunities to fluidization scientists and technologists. The potential of this growing field calls for reconsideration of some of the typical design and operation guidelines and criteria, with the goal of exploiting the inherently good thermal performances of gas-fluidized beds at their best. "Creative" and non-conventional design and operation of fluidized beds, like those based on internal and external solids circulation, may be beneficial to the enhancement of thermal diffusivity and surface-to-bed heat transfer, improving the potential for application in the very demanding context of CSP with thermal energy storage. This paper investigated: i) a fluidized bed configuration with an uneven distribution of the fluidizing gas to promote vortices in the scale of bed height (internal solids circulation); ii) a dual fluidized bed configuration characterized by an external solids circulation achieved by the operation of a riser and a bubbling fluidized bed. CFD simulations showed the hydrodynamics conditions under which the internal solids circulation was established. The hydrodynamic characterization of the external solids circulation was achieved by an experimental study carried out with different cold models. The dual fluidized bed system was optimized in terms of operating conditions and geometrical features of the connections between two fluidized beds.

A parametric investigation on a solar dish-Stirling system

NASA Astrophysics Data System (ADS)

Gholamalizadeh, Ehsan; Chung, Jae Dong

2018-06-01

The aim of this study is to analyze the performance of a solar dish-Stirling system. A mathematical model for the overall thermal efficiency of the solar-powered high-temperature-differential dish-Stirling engine is described. This model takes into account pressure losses due to fluid friction which is internal to the engine, mechanical friction between the moving parts, actual heat transfer includes the effects of both internal and external irreversibilities of the cycle and finite regeneration processes time. Validation was done through comparison with the actual power output of the "EuroDish" system. Moreover, the effects of dish diameter and working fluid on the performance of the system were studied. An increase of about 7.2% was observed for the power output using hydrogen as the working fluid rather than helium. Also, the focal distance for any diameter of dish was calculated.

KTX circuit model and discharge waveform prediction

NASA Astrophysics Data System (ADS)

Bai, Wei; Lan, T.; Mao, W. Z.; You, W.; Li, H.; Liu, A. D.; Xie, J. L.; Wan, S. D.; Liu, W. D.; Yang, L.; Fu, P.; Xiao, C. J.; Ding, W. X.

2013-10-01

The Keda Torus eXperiment (KTX) is a constructing reversed field pinch (RFP) device in University of Science and Technology of China. The KTX power supply system includes the Ohmic heating, field shaping and toroidal power supply systems, which produce the Ohmic field, equilibrium field and toroidal field, respectively. The detailed circuit model will be introduced in this poster. Another purpose is to predict its discharge waveforms using the modified Bessel function mode (MBFM), which describes the evolution of plasma current and magnetic flux in RFP base on Taylor theory. Furthermore, the power supply requirements of external field shaping winding are also predicted in the model, which will be very helpful for the design of plasma equilibrium controlling system. Supported by ITER-China program (No. 2011GB106000), NNSFC (Nos. 10990210, 10990211, 10335060 and 10905057), CPSF (No. 20080440104), YIF (No. WK2030040019) and KIPCAS (No. kjcx-yw-n28).

Key issues in theoretical and functional pneumatic design

NASA Astrophysics Data System (ADS)

Xu, Z. G.; Yang, D. Y.; Liu, W. M.; Liu, T. T.

2017-10-01

This paper studies the energy release of the pneumatic engine in different thermodynamic processes, the isothermal process is the highest power output process, while adiabatic process is the lowest energy output process, and the energy release of the pneumatic engine is a multi-state thermodynamic process between them. Therefore heat exchanging should be increased between the pneumatic engine and the outer space, the gas expansion process in the cylinder should be as close as possible to the isothermal process. Heat exchange should be increased between the cylinder and the external spaces. Secondly, the fin structure is studied to increase the heat exchanging between the cylinder body and the outside space. The upper part has fin structures and the lower cylinder has no fin structure, this structure improved the working efficiency of pneumatic engine. Finally the cam and the hydraulic bottle of pneumatic engines are designed. Simulation and theoretical calculation are used to the analysis of the whole structure, which lay the foundation for the manufacturing and design of the pneumatic engines.

Adaptive beam shaping by controlled thermal lensing in optical elements

NASA Astrophysics Data System (ADS)

Arain, Muzammil A.; Quetschke, Volker; Gleason, Joseph; Williams, Luke F.; Rakhmanov, Malik; Lee, Jinho; Cruz, Rachel J.; Mueller, Guido; Tanner, D. B.; Reitze, David. H.

2007-04-01

We describe an adaptive optical system for use as a tunable focusing element. The system provides adaptive beam shaping via controlled thermal lensing in the optical elements. The system is agile, remotely controllable, touch free, and vacuum compatible; it offers a wide dynamic range, aberration-free focal length tuning, and can provide both positive and negative lensing effects. Focusing is obtained through dynamic heating of an optical element by an external pump beam. The system is especially suitable for use in interferometric gravitational wave interferometers employing high laser power, allowing for in situ control of the laser modal properties and compensation for thermal lensing of the primary laser. Using CO2 laser heating of fused-silica substrates, we demonstrate a focal length variable from infinity to 4.0 m, with a slope of 0.082 diopter/W of absorbed heat. For on-axis operation, no higher-order modes are introduced by the adaptive optical element. Theoretical modeling of the induced optical path change and predicted thermal lens agrees well with measurement.

Adaptive beam shaping by controlled thermal lensing in optical elements.

PubMed

Arain, Muzammil A; Quetschke, Volker; Gleason, Joseph; Williams, Luke F; Rakhmanov, Malik; Lee, Jinho; Cruz, Rachel J; Mueller, Guido; Tanner, D B; Reitze, David H

2007-04-20

We describe an adaptive optical system for use as a tunable focusing element. The system provides adaptive beam shaping via controlled thermal lensing in the optical elements. The system is agile, remotely controllable, touch free, and vacuum compatible; it offers a wide dynamic range, aberration-free focal length tuning, and can provide both positive and negative lensing effects. Focusing is obtained through dynamic heating of an optical element by an external pump beam. The system is especially suitable for use in interferometric gravitational wave interferometers employing high laser power, allowing for in situ control of the laser modal properties and compensation for thermal lensing of the primary laser. Using CO(2) laser heating of fused-silica substrates, we demonstrate a focal length variable from infinity to 4.0 m, with a slope of 0.082 diopter/W of absorbed heat. For on-axis operation, no higher-order modes are introduced by the adaptive optical element. Theoretical modeling of the induced optical path change and predicted thermal lens agrees well with measurement.

Intrapulpal temperatures during pulsed Nd:YAG laser treatment of dentin, in vitro.

PubMed

White, J M; Fagan, M C; Goodis, H E

1994-03-01

Lasers are being used for soft tissue removal, caries removal, and treatment of root surface sensitivity. One concern for laser safety is that the heat produced at the irradiated root surface may diffuse to the pulp causing irreversible pulpal damage. To test this heat diffusion, copper-constantan thermocouples were inserted into the radicular pulp canals of extracted teeth. Simulating direct exposure which might occur during gingival excision, superficial caries removal, and modification of the dentin surface for treatment of root surface sensitivity, a 2 mm2 area of the external root surface was uniformly irradiated with a pulsed Nd:YAG laser using a 320 microns diameter fiber optic contact probe. Power was varied from 0.3 to 3.0 W with frequencies of 10 and 20 Hz. Temperature changes during cavity preparations using a high speed handpiece with air coolant were also recorded. Repeated measures ANOVA (P < or = 0.05) indicated that intrapulpal temperatures increased as a function of power, frequency, and time. Intrapulpal temperatures decreased as remaining dentin thickness (0.2 to 2.0 mm) increased for each laser parameter. Irradiation of dentin using a Nd:YAG pulsed laser, within the treatment times, powers, and frequencies with adequate remaining dentin thickness, as outlined in this paper, should not cause devitalizing intrapulpal temperature rises.

Advanced modelling of the transport phenomena across horizontal clothing microclimates with natural convection.

PubMed

Mayor, T S; Couto, S; Psikuta, A; Rossi, R M

2015-12-01

The ability of clothing to provide protection against external environments is critical for wearer's safety and thermal comfort. It is a function of several factors, such as external environmental conditions, clothing properties and activity level. These factors determine the characteristics of the different microclimates existing inside the clothing which, ultimately, have a key role in the transport processes occurring across clothing. As an effort to understand the effect of transport phenomena in clothing microclimates on the overall heat transport across clothing structures, a numerical approach was used to study the buoyancy-driven heat transfer across horizontal air layers trapped inside air impermeable clothing. The study included both the internal flow occurring inside the microclimate and the external flow occurring outside the clothing layer, in order to analyze the interdependency of these flows in the way heat is transported to/from the body. Two-dimensional simulations were conducted considering different values of microclimate thickness (8, 25 and 52 mm), external air temperature (10, 20 and 30 °C), external air velocity (0.5, 1 and 3 m s(-1)) and emissivity of the clothing inner surface (0.05 and 0.95), which implied Rayleigh numbers in the microclimate spanning 4 orders of magnitude (9 × 10(2)-3 × 10(5)). The convective heat transfer coefficients obtained along the clothing were found to strongly depend on the transport phenomena in the microclimate, in particular when natural convection is the most important transport mechanism. In such scenario, convective coefficients were found to vary in wavy-like manner, depending on the position of the flow vortices in the microclimate. These observations clearly differ from data in the literature for the case of air flow over flat-heated surfaces with constant temperature (which shows monotonic variations of the convective heat transfer coefficients, along the length of the surface). The flow patterns and temperature fields in the microclimates were found to strongly depend on the characteristics of the external boundary layer forming along the clothing and on the distribution of temperature in the clothing. The local heat transfer rates obtained in the microclimate are in marked contrast with those found in the literature for enclosures with constant-temperature active walls. These results stress the importance of coupling the calculation of the internal and the external flows and of the heat transfer convective and radiative components, when analyzing the way heat is transported to/from the body.

Experimental study of forced convective heat transfer from a vertical tube conveying dilute Ag/DI water nanofluids in a cross flow of air

NASA Astrophysics Data System (ADS)

Mohammadian, Shahabeddin Keshavarz; Layeghi, Mohammad; Hemmati, Mansor

2013-03-01

Forced convective heat transfer from a vertical circular tube conveying deionized (DI) water or very dilute Ag-DI water nanofluids (less than 0.02% volume fraction) in a cross flow of air has been investigated experimentally. Some experiments have been performed in a wind tunnel and heat transfer characteristics such as thermal conductance, effectiveness, and external Nusselt number has been measured at different air speeds, liquid flow rates, and nanoparticle concentrations. The cross flow of air over the tube and the liquid flow in the tube were turbulent in all cases. The experimental results have been compared and it has been found that suspending Ag nanoparticles in the base fluid increases thermal conductance, external Nusselt number, and effectiveness. Furthermore, by increasing the external Reynolds number, the external Nusselt number, effectiveness, and thermal conductance increase. Also, by increasing internal Reynolds number, the thermal conductance and external Nusselt number enhance while the effectiveness decreases.

Flexible Cryogenic Temperature and Liquid-Level Probes

NASA Technical Reports Server (NTRS)

Haberbusch, Mark

2005-01-01

Lightweight, flexible probes have been developed for measuring temperatures at multiple locations in tanks that contain possibly pressurized cryogenic fluids. If the fluid in a given tank is subcritical (that is, if it consists of a liquid and its vapor), then in one of two modes of operation, the temperature measurements made by a probe of this type can be used to deduce the approximate level of the liquid. The temperature sensors are silicon diodes located at intervals along a probe. If the probe is to be used to measure a temperature gradient along a given axis in the tank, then the probe must be mounted along that axis. In the temperature-measurement mode, a constant small electric current is applied to each diode and the voltage across the diode a known function of the current and temperature is measured as an indication of its temperature. For the purpose of this measurement, small electric current signifies a current that is not large enough to cause a significant increase in the measured temperature. More specifically, the probe design calls for a current of 10 A, which, in the cryogenic temperature range of interest, generates heat at a rate of only about 0.01 mW per diode. In the liquid-level-sensing mode, one applies a larger current (30 mA) to each diode so as to heat each diode appreciably (with a power of about 36 mW in the temperature range of interest). Because the liquid cools the diode faster than does the vapor, the temperature of the diode is less when the diode is immersed in the liquid than when it is above the surface of the liquid. Thus, the temperature (voltage) reading from each diode can be used to determine whether the liquid level is above or below the diode, and one can deduce that the liquid level lies between two adjacent diodes, the lower one of which reads a significantly lower temperature. The aforementioned techniques for measuring temperature and deducing liquid level are not new. What is new here are the designs of the probes and of associated external electronic circuitry. In each probe, the diodes and the lead wires are embedded in a strong, lightweight, flexible polyimide strip. Each probe is constructed as an integral unit that includes a multipin input/output plug or socket for solderless connection of the lead wires to the external circuitry. The polyimide strip includes mounting tabs with holes that can accommodate rivets, screws, or other fasteners. Alternatively, a probe can be mounted by use of an epoxy. A probe can be manufactured to almost any length or width, and the diodes can be embedded at almost any desired location along and across the polyimide strip. In designing a probe for a specific application, one seeks a compromise between (1) minimizing the number of diodes in order to minimize the complexity of input/output connections and external electronic circuitry while (2) using enough diodes to obtain the required precision. Optionally, to minimize spurious heating of the cryogenic fluid, the external circuitry can be designed to apply power to the probe only during brief measurement intervals. Assuming that the external circuitry is maintained at a steady temperature, a power-on interval of only a few seconds is sufficient to obtain accurate data on temperatures and/or the height of the liquid/vapor interface.

Flexible Cryogenic Temperature and Liquid-Level Probes

NASA Technical Reports Server (NTRS)

Haberbusch, Mark

2003-01-01

Lightweight, flexible probes have been developed for measuring temperatures at multiple locations in tanks that contain possibly pressurized cryogenic fluids. If the fluid in a given tank is subcritical (that is, if it consists of a liquid and its vapor), then in one of two modes of operation, the temperature measurements made by a probe of this type can be used to deduce the approximate level of the liquid. The temperature sensors are silicon diodes located at intervals along a probe. If the probe is to be used to measure a temperature gradient along a given axis in the tank, then the probe must be mounted along that axis. In the non-liquid-level-sensing temperature-measurement mode, a constant small electric current is applied to each diode and the voltage across the diode . a known function of the current and temperature . is measured as an indication of its temperature. For the purpose of this measurement, "small electric current" signifies a current that is not large enough to cause a significant increase in the measured temperature. More specifically, the probe design calls for a current of 10 A, which, in the cryogenic temperature range of interest, generates heat at a rate of only about 0.01 mW per diode. In the liquid-level-sensing mode, one applies a larger current (30 mA) to each diode so as to heat each diode appreciably (with a power of about 36 mW in the temperature range of interest). Because the liquid cools the diode faster than does the vapor, the temperature of the diode is less when diode is immersed in the liquid than when it is above the surface of the liquid. Thus, the temperature (voltage) reading from each diode can be used to determine whether the liquid level is above or below the diode, and one can deduce that the liquid level lies between two adjacent diodes, the lower one of which reads a significantly lower temperature. The aforementioned techniques for measuring temperature and deducing liquid level are not new. What is new here are the designs of the probes and of associated external electronic circuitry. In each probe, the diodes and the lead wires are embedded in a strong, lightweight, flexible polyimide strip. Each probe is constructed as an integral unit that includes a multipin input/output plug or socket for solderless connection of the lead wires to the external circuitry. The polyimide strip includes mounting tabs with holes that can accommodate rivets, screws, or other fasteners. Alternatively, a probe can be mounted by use of an epoxy. A probe can be manufactured to almost any length or width, and the diodes can be embedded at almost any desired locations along and across the polyimide strip. In designing a probe for a specific application, one seeks a compromise between (1) minimizing the number of diodes in order to minimize the complexity of input/output connections and external electronic circuitry while (2) using enough diodes to obtain the required precision. Optionally, to minimize spurious heating of the cryogenic fluid, the external circuitry can be designed to apply power to the probe only during brief measurement intervals. Assuming that the external circuitry is maintained at a steady temperature, a power-on interval of only a few seconds is sufficient to obtain accurate data on temperatures and/or the height of the liquid/vapor interface.

Optothermal transfer simulation in laser-irradiated human dentin.

PubMed

Moriyama, Eduardo H; Zangaro, Renato A; Lobo, Paulo D C; Villaverde, Antonio Balbin; Pacheco, Marcos T; Watanabe, Ii-Sei; Vitkin, Alex

2003-04-01

Laser technology has been studied as a potential replacement to the conventional dental drill. However, to prevent pulpal cell damage, information related to the safety parameters using high-power lasers in oral mineralized tissues is needed. In this study, the heat distribution profiles at the surface and subsurface regions of human dentine samples irradiated with a Nd:YAG laser were simulated using Crank-Nicolson's finite difference method for different laser energies and pulse durations. Heat distribution throughout the dentin layer, from the external dentin surface to the pulp chamber wall, were calculated in each case, to investigate the details of pulsed laser-hard dental tissue interactions. The results showed that the final temperature at the pulp chamber wall and at the dentin surface are strongly dependent on the pulse duration, exposure time, and the energy contained in each pulse.

Extension of the supercritical carbon dioxide brayton cycle to low reactor power operation: investigations using the coupled anl plant dynamics code-SAS4A/SASSYS-1 liquid metal reactor code system.

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

Moisseytsev, A.; Sienicki, J. J.

2012-05-10

Significant progress has been made on the development of a control strategy for the supercritical carbon dioxide (S-CO{sub 2}) Brayton cycle enabling removal of power from an autonomous load following Sodium-Cooled Fast Reactor (SFR) down to decay heat levels such that the S-CO{sub 2} cycle can be used to cool the reactor until decay heat can be removed by the normal shutdown heat removal system or a passive decay heat removal system such as Direct Reactor Auxiliary Cooling System (DRACS) loops with DRACS in-vessel heat exchangers. This capability of the new control strategy eliminates the need for use of amore » separate shutdown heat removal system which might also use supercritical CO{sub 2}. It has been found that this capability can be achieved by introducing a new control mechanism involving shaft speed control for the common shaft joining the turbine and two compressors following reduction of the load demand from the electrical grid to zero. Following disconnection of the generator from the electrical grid, heat is removed from the intermediate sodium circuit through the sodium-to-CO{sub 2} heat exchanger, the turbine solely drives the two compressors, and heat is rejected from the cycle through the CO{sub 2}-to-water cooler. To investigate the effectiveness of shaft speed control, calculations are carried out using the coupled Plant Dynamics Code-SAS4A/SASSYS-1 code for a linear load reduction transient for a 1000 MWt metallic-fueled SFR with autonomous load following. No deliberate motion of control rods or adjustment of sodium pump speeds is assumed to take place. It is assumed that the S-CO{sub 2} turbomachinery shaft speed linearly decreases from 100 to 20% nominal following reduction of grid load to zero. The reactor power is calculated to autonomously decrease down to 3% nominal providing a lengthy window in time for the switchover to the normal shutdown heat removal system or for a passive decay heat removal system to become effective. However, the calculations reveal that the compressor conditions are calculated to approach surge such that the need for a surge control system for each compressor is identified. Thus, it is demonstrated that the S-CO{sub 2} cycle can operate in the initial decay heat removal mode even with autonomous reactor control. Because external power is not needed to drive the compressors, the results show that the S-CO{sub 2} cycle can be used for initial decay heat removal for a lengthy interval in time in the absence of any off-site electrical power. The turbine provides sufficient power to drive the compressors. Combined with autonomous reactor control, this represents a significant safety advantage of the S-CO{sub 2} cycle by maintaining removal of the reactor power until the core decay heat falls to levels well below those for which the passive decay heat removal system is designed. The new control strategy is an alternative to a split-shaft layout involving separate power and compressor turbines which had previously been identified as a promising approach enabling heat removal from a SFR at low power levels. The current results indicate that the split-shaft configuration does not provide any significant benefits for the S-CO{sub 2} cycle over the current single-shaft layout with shaft speed control. It has been demonstrated that when connected to the grid the single-shaft cycle can effectively follow the load over the entire range. No compressor speed variation is needed while power is delivered to the grid. When the system is disconnected from the grid, the shaft speed can be changed as effectively as it would be with the split-shaft arrangement. In the split-shaft configuration, zero generator power means disconnection of the power turbine, such that the resulting system will be almost identical to the single-shaft arrangement. Without this advantage of the split-shaft configuration, the economic benefits of the single-shaft arrangement, provided by just one turbine and lower losses at the design point, are more important to the overall cycle performance. Therefore, the single-shaft configuration shall be retained as the reference arrangement for S-CO{sub 2} cycle power converter preconceptual designs. Improvements to the ANL Plant Dynamics Code have been carried out. The major code improvement is the introduction of a restart capability which simplifies investigation of control strategies for very long transients. Another code modification is transfer of the entire code to a new Intel Fortran complier; the execution of the code using the new compiler was verified by demonstrating that the same results are obtained as when the previous Compaq Visual Fortran compiler was used.« less

The DC and AC insulating properties of magnetic fluids based on transformer oil

NASA Astrophysics Data System (ADS)

Tomo, L.; Marton, K.; Herchl, F.; Kopanský, P.; Potoová, I.; Koneracká, M.; Timko, M.

2006-01-01

The AC-dielectric breakdown was investigated in magnetic fluids based on transformer oil TECHNOL US 4000 for two orientations of external magnetic field (B E and B E) and in B = 0. The found results were compared with those obtained formerly for the DC-dielectric breakdown. The observations of the time development of the AC-dielectric breakdown showed the presence of partial discharges long before the complete breakdown occurrence, while for DC-dielectric breakdown a complete breakdown of the gap next to the onset of a measurable ionization was characteristic. The comparison of the AC-dielectric breakdown strengths of pure transformer oil and transformer-oil-based magnetic fluid showed better dielectric properties of magnetic fluid in external magnetic field and comparable, but not worse, in B = 0. Regarding to the better heat transfer, provided by magnetic fluids, they could be used in power transformers as insulating fluids.

Using Waste Heat for External Processes (English/Chinese) (Fact Sheet) (in Chin3se; English)

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

Not Available

Chinese translation of the Using Waste Heat for External Processes fact sheet. Provides suggestions on how to use waste heat in industrial applications. The temperature of exhaust gases from fuel-fired industrial processes depends mainly on the process temperature and the waste heat recovery method. Figure 1 shows the heat lost in exhaust gases at various exhaust gas temperatures and percentages of excess air. Energy from gases exhausted from higher temperature processes (primary processes) can be recovered and used for lower temperature processes (secondary processes). One example is to generate steam using waste heat boilers for the fluid heaters used inmore » petroleum crude processing. In addition, many companies install heat exchangers on the exhaust stacks of furnaces and ovens to produce hot water or to generate hot air for space heating.« less

Specifics of heat and mass transfer in spherical dimples under the effect of external factors

NASA Astrophysics Data System (ADS)

Shchukin, A. V.; Il'inkov, A. V.; Takmovtsev, V. V.; Khabibullin, I. I.

2017-06-01

The specifics are examined of heat transfer enhancement with spherical dimples under the effect of factors important for practice and characteristic of cooling systems of gas-turbine engines and power units. This experimental investigation deals with the effect of the following factors on the flow in a channel with hemispherical dimples: continuous air swirl in an annulus with dimples on its concave wall, dimples on the convex or concave wall of a curved rectangular channel, imposition of regular velocity fluctuations on the external flow in a straight rectangular channel, and adverse or favorable pressure gradient along the flow direction. The flow is turbulent. Reynolds numbers based on the channel hydraulic diameter are on the order of 104. Results of the investigation of a model of a two-cavity diffuser dimple proposed by the authors are presented. It has been found that results for channels with spherical dimples and for smooth channels differ not only quantitatively but also qualitatively. Thus, if the effect of centrifugal mass forces on convex and concave surfaces with hemispherical dimples and in a smooth channel is almost the same (quantitative and qualitative indicators are identical), the pressure gradient in the flow direction brings about the drastically opposite results. At the same time, the quantitative contribution to a change in heat transfer in hemispherical dimples is different and depends on the impact type. The results are discussed with the use of physical models created on the basis of the results of flow visualization studies and data on the turbulence intensity, pressure coefficient, etc. Results of the investigations suggest that application of spherical dimples under nonstandard conditions requires the calculated heat transfer to be corrected to account for one or another effect.

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.

24 CFR 3280.702 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-04-01

... (in the case of a heat pump) heating system which includes the refrigerant pump (compressor) and the external heat exchanger. Air conditioning evaporator section means a heat exchanger used to cool or (in the case of a heat pump) heat air for use in comfort cooling (or heating) the living space. Air...

24 CFR 3280.702 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-04-01

... (in the case of a heat pump) heating system which includes the refrigerant pump (compressor) and the external heat exchanger. Air conditioning evaporator section means a heat exchanger used to cool or (in the case of a heat pump) heat air for use in comfort cooling (or heating) the living space. Air...

On a Heat Exchange Problem under Sharply Changing External Conditions

NASA Astrophysics Data System (ADS)

Khishchenko, K. V.; Charakhch'yan, A. A.; Shurshalov, L. V.

2018-02-01

The heat exchange problem between carbon particles and an external environment (water) is stated and investigated based on the equations of heat conducting compressible fluid. The environment parameters are supposed to undergo large and fast variations. In the time of about 100 μs, the temperature of the environment first increases from the normal one to 2400 K, is preserved at this level for about 60 μs, and then decreases to 300 K during approximately 50 μs. At the same periods of time, the pressure of the external environment increases from the normal one to 67 GPa, is preserved at this level, and then decreases to zero. Under such external conditions, the heating of graphite particles of various sizes, their phase transition to the diamond phase, and the subsequent unloading and cooling almost to the initial values of the pressure and temperature without the reverse transition from the diamond to the graphite phase are investigated. Conclusions about the maximal size of diamond particles that can be obtained in experiments on the shock compression of the mixture of graphite with water are drawn.

Turbine Vane External Heat Transfer. Volume 1: Analytical and Experimental Evaluation of Surface Heat Transfer Distributions with Leading Edge Showerhead Film Cooling

NASA Technical Reports Server (NTRS)

Turner, E. R.; Wilson, M. D.; Hylton, L. D.; Kaufman, R. M.

1985-01-01

Progress in predictive design capabilities for external heat transfer to turbine vanes was summarized. A two dimensional linear cascade (previously used to obtain vane surface heat transfer distributions on nonfilm cooled airfoils) was used to examine the effect of leading edge shower head film cooling on downstream heat transfer. The data were used to develop and evaluate analytical models. Modifications to the two dimensional boundary layer model are described. The results were used to formulate and test an effective viscosity model capable of predicting heat transfer phenomena downstream of the leading edge film cooling array on both the suction and pressure surfaces, with and without mass injection.

TRANSFORMER

DOEpatents

Baker, W.R.

1959-08-25

Transformers of a type adapted for use with extreme high power vacuum tubes where current requirements may be of the order of 2,000 to 200,000 amperes are described. The transformer casing has the form of a re-entrant section being extended through an opening in one end of the cylinder to form a coaxial terminal arrangement. A toroidal multi-turn primary winding is disposed within the casing in coaxial relationship therein. In a second embodiment, means are provided for forming the casing as a multi-turn secondary. The transformer is characterized by minimized resistance heating, minimized external magnetic flux, and an economical construction.

Metal vapor arc switch electromagnetic accelerator technology

NASA Technical Reports Server (NTRS)

Mongeau, P. P.

1984-01-01

A multielectrode device housed in an insulator vacuum vessel, the metal vapor vacuum switch has high power capability and can hold off voltages up to the 100 kilovolt level. Such switches can be electronically triggered and can interrupt or commutate at a zero current crossing. The physics of arc initiation, arc conduction, and interruption are examined, including material considerations; inefficiencies; arc modes; magnetic field effects; passive and forced extinction; and voltage recovery. Heating, electrode lifetime, device configuration, and external circuit configuration are discussed. The metal vapor vacuum switch is compared with SCRs, GTOs, spark gaps, ignitrons, and mechanical breakers.

Bipolar Nickel-Metal Hydride Battery Development Project

NASA Technical Reports Server (NTRS)

Cole, John H.

1999-01-01

This paper reviews the development of the Electro Energy, Inc.'s bipolar nickel metal hydride battery. The advantages of the design are that each cell is individually sealed, and that there are no external cell terminals, no electrode current collectors, it is compatible with plastic bonded electrodes, adaptable to heat transfer fins, scalable to large area, capacity and high voltage. The design will allow for automated flexible manufacturing, improved energy and power density and lower cost. The development and testing of the battery's component are described. Graphic presentation of the results of many of the tests are included.

Fiber-coupled pillar array as a highly pure and stable single-photon source

NASA Astrophysics Data System (ADS)

Odashima, S.; Sasakura, H.; Nakajima, H.; Kumano, H.

2017-12-01

A highly pure and stable single-photon source is prepared that comprises a well-designed pillar array, in which each pillar contains only a few InAs quantum dots. A nano-pillar in this array is in direct contact with a fiber end surface and cooled in a liquid-He bath. Auto-correlation measurements show that this source provides an average g(2)(0) value of 0.0174 in the measured excitation-power range. This photon source and fiber coupling are quite rigid against external disturbances such as cooling-heating cycles and vibration, with long-term stability.

Heat transfer test of an 0.006-scale thin-skin thermocouple space shuttle model (50-0, 41-T) in the NASA-Ames Research Center 3.5-foot hypersonic wind tunnel at Mach 5.3 (IH28), volume 1

NASA Technical Reports Server (NTRS)

Cummings, J. W.; Foster, T. F.; Lockman, W. K.

1976-01-01

Data obtained from a heat transfer test conducted on an 0.006-scale space shuttle orbiter and external tank in the NASA-Ames Research Center 3.5-foot Hypersonic Wind Tunnel are presented. The purpose of this test was to obtain data under simulated return-to-launch-site abort conditions. Configurations tested were integrated orbiter and external tank, orbiter alone, and external tank alone at angles of attack of 0, + or - 30, + or - 60, + or - 90, and + or - 120 degrees. Runs were conducted at Mach numbers of 5.2 and 5.3 for Reynolds numbers of 1.0 and 4.0 million per foot, respectively. Heat transfer data were obtained from 75 orbiter and 75 external tank iron-constantan thermocouples.

Development of a thermal and structural analysis procedure for cooled radial turbines

NASA Technical Reports Server (NTRS)

Kumar, Ganesh N.; Deanna, Russell G.

1988-01-01

A procedure for computing the rotor temperature and stress distributions in a cooled radial turbine is considered. Existing codes for modeling the external mainstream flow and the internal cooling flow are used to compute boundary conditions for the heat transfer and stress analyses. An inviscid, quasi three-dimensional code computes the external free stream velocity. The external velocity is then used in a boundary layer analysis to compute the external heat transfer coefficients. Coolant temperatures are computed by a viscous one-dimensional internal flow code for the momentum and energy equation. These boundary conditions are input to a three-dimensional heat conduction code for calculation of rotor temperatures. The rotor stress distribution may be determined for the given thermal, pressure and centrifugal loading. The procedure is applied to a cooled radial turbine which will be tested at the NASA Lewis Research Center. Representative results from this case are included.

Development of a thermal and structural analysis procedure for cooled radial turbines

NASA Technical Reports Server (NTRS)

Kumar, Ganesh N.; Deanna, Russell G.

1988-01-01

A procedure for computing the rotor temperature and stress distributions in a cooled radial turbine are considered. Existing codes for modeling the external mainstream flow and the internal cooling flow are used to compute boundary conditions for the heat transfer and stress analysis. The inviscid, quasi three dimensional code computes the external free stream velocity. The external velocity is then used in a boundary layer analysis to compute the external heat transfer coefficients. Coolant temperatures are computed by a viscous three dimensional internal flow cade for the momentum and energy equation. These boundary conditions are input to a three dimensional heat conduction code for the calculation of rotor temperatures. The rotor stress distribution may be determined for the given thermal, pressure and centrifugal loading. The procedure is applied to a cooled radial turbine which will be tested at the NASA Lewis Research Center. Representative results are given.

Brain Tumor Hyperthermia with Static and Moving Seeds

NASA Astrophysics Data System (ADS)

Molloy, Janelle Arlene

1990-01-01

Thermodynamic studies are presented for both static and moving ferromagnetic "seeds" imbedded in biological media. These studies were performed in support of the development of a system which delivers localized hyperthermia to deep-seated brain tumors. In this system, a magnetic "seed" of approximately 5 mm dimension (length and diameter) is remotely repositioned within the brain by an externally produced magnetic field. The seed is inductively heated and repositioned throughout the tumor volume. An induction heating system was built for experimental use with tissue phantoms and animals. The maximum level of direct tissue heating produced by this system was measured in vivo in three animals. An upper limit on the power absorption was placed at 0.46 mW cm^{ -3}, a factor of 10^{-4 } below the power density produced in ferromagnetic seeds by the same system. Measurements were made of the temporal and spatial dependence of the temperature rise in the vicinity of a statically placed 6 mm diameter nickel sphere, in vivo in four pigs, and in one which was euthanized. These results were compared to a theroetical model which was based on a point source solution to the thermal diffusion equation and estimates of blood flow rates, tissue thermal conductivity and seed power absorption were found using a parameter estimation algorithm. Studies were also made of the temperature gradients produced by a heated iron ellipsoid of 4.8 mm diameter and 9.6 mm length in a brain tissue phantom. Temperature measurements were made both with the seed statically imbedded in the tissue phantom and with the phantom moving at a constant velocity of 0.11 mm s^{-1 } with respect to the seed. These static and moving data were compared to obtain an estimate for the thermal field and convective cooling of a moving seed. In addition, an exploratory study was performed in which the dependence of seed heating efficiency on material and geometry were tested. A "hybrid" seed was developed consisting of a permanent magnet core surrounded by a non -magnetic spacing material and a 0.5 mm thick ferromagnetic outer sleeve. This seed was designed to accommodate potentially conflicting magnetic force and induction heating requirements.

10 CFR Appendix Z to Subpart B of... - Uniform Test Method for Measuring the Energy Consumption of External Power Supplies

Code of Federal Regulations, 2010 CFR

2010-01-01

... of External Power Supplies Z Appendix Z to Subpart B of Part 430 Energy DEPARTMENT OF ENERGY ENERGY... Power Supplies 1. Scope: This appendix covers the test requirements used to measure energy consumption of external power supplies. 2. Definitions: The following definitions are for the purposes of...

10 CFR Appendix Z to Subpart B of... - Uniform Test Method for Measuring the Energy Consumption of External Power Supplies

Code of Federal Regulations, 2011 CFR

2011-01-01

... of External Power Supplies Z Appendix Z to Subpart B of Part 430 Energy DEPARTMENT OF ENERGY ENERGY... Power Supplies 1. Scope: This appendix covers the test requirements used to measure energy consumption of external power supplies. 2. Definitions: The following definitions are for the purposes of...

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

Deschenes, Austin; Muneer, Sadid; Akbulut, Mustafa

Thermal assistance has been shown to significantly reduce the required operation power for spin torque transfer magnetic random access memory (STT-MRAM). Proposed heating methods include modified material stack compositions that result in increased self-heating or external heat sources. Here, we analyze the self-heating process of a standard perpendicular magnetic anisotropy STT-MRAM device through numerical simulations in order to understand the relative contributions of Joule, thermoelectric Peltier and Thomson, and tunneling junction heating. A 2D rotationally symmetric numerical model is used to solve the coupled electro-thermal equations including thermoelectric effects and heat absorbed or released at the tunneling junction. We comparemore » self-heating for different common passivation materials, positive and negative electrical current polarity, and different device thermal anchoring and boundaries resistance configurations. The variations considered are found to result in significant differences in maximum temperatures reached. Average increases of 3 K, 10 K, and 100 K for different passivation materials, positive and negative polarity, and different thermal anchoring configurations, respectively, are observed. Furthermore, the highest temperatures, up to 424 K, are obtained for silicon dioxide as the passivation material, positive polarity, and low thermal anchoring with thermal boundary resistance configurations. Interestingly it is also found that due to the tunneling heat, Peltier effect, device geometry, and numerous interfacial layers around the magnetic tunnel junction (MTJ), most of the heat is dissipated on the lower potential side of the magnetic junction. We have observed this asymmetry in heating and is important as thermally assisted switching requires heating of the free layer specifically and this will be significantly different for the two polarity operations, set and reset.« less

Non-inductive current drive and transport in high βN plasmas in JET

NASA Astrophysics Data System (ADS)

Voitsekhovitch, I.; Alper, B.; Brix, M.; Budny, R. V.; Buratti, P.; Challis, C. D.; Ferron, J.; Giroud, C.; Joffrin, E.; Laborde, L.; Luce, T. C.; McCune, D.; Menard, J.; Murakami, M.; Park, J. M.; JET-EFDA contributors

2009-05-01

A route to stationary MHD stable operation at high βN has been explored at the Joint European Torus (JET) by optimizing the current ramp-up, heating start time and the waveform of neutral beam injection (NBI) power. In these scenarios the current ramp-up has been accompanied by plasma pre-heat (or the NBI has been started before the current flat-top) and NBI power up to 22 MW has been applied during the current flat-top. In the discharges considered transient total βN ≈ 3.3 and stationary (during high power phase) βN ≈ 3 have been achieved by applying the feedback control of βN with the NBI power in configurations with monotonic or flat core safety factor profile and without an internal transport barrier (ITB). The transport and current drive in this scenario is analysed here by using the TRANSP and ASTRA codes. The interpretative analysis performed with TRANSP shows that 50-70% of current is driven non-inductively; half of this current is due to the bootstrap current which has a broad profile since an ITB was deliberately avoided. The GLF23 transport model predicts the temperature profiles within a ±22% discrepancy with the measurements over the explored parameter space. Predictive simulations with this model show that the E × B rotational shear plays an important role for thermal ion transport in this scenario, producing up to a 40% increase of the ion temperature. By applying transport and current drive models validated in self-consistent simulations of given reference scenarios in a wider parameter space, the requirements for fully non-inductive stationary operation at JET are estimated. It is shown that the strong stiffness of the temperature profiles predicted by the GLF23 model restricts the bootstrap current at larger heating power. In this situation full non-inductive operation without an ITB can be rather expensive strongly relying on the external non-inductive current drive sources.

Design and operations of a load-tolerant external conjugate-T matching system for the A2 ICRH antennas at JET

NASA Astrophysics Data System (ADS)

Monakhov, I.; Graham, M.; Blackman, T.; Dowson, S.; Durodie, F.; Jacquet, P.; Lehmann, J.; Mayoral, M.-L.; Nightingale, M. P. S.; Noble, C.; Sheikh, H.; Vrancken, M.; Walden, A.; Whitehurst, A.; Wooldridge, E.; Contributors, JET-EFDA

2013-08-01

A load-tolerant external conjugate-T (ECT) impedance matching system for two A2 ion cyclotron resonance heating (ICRH) antennas was successfully put into operation at JET. The system allows continuous injection of the radio-frequency (RF) power into plasma in the presence of strong antenna loading perturbations caused by edge-localized modes (ELMs). Reliable ECT performance was demonstrated under a variety of antenna loading conditions including H-mode plasmas with radial outer gaps (ROGs) in the range 4-14 cm. The high resilience to ELMs predicted during the circuit simulations was fully confirmed experimentally. Dedicated arc-detection techniques and real-time matching algorithms were developed as a part of the ECT project. The new advanced wave amplitude comparison system has proven highly efficient in detection of arcs both between and during ELMs. The ECT system has allowed the delivery of up to 4 MW of RF power without trips into plasmas with type-I ELMs. Together with the 3 dB system and the ITER-like antenna, the ECT has brought the total RF power coupled to ELMy plasma to over 8 MW, considerably enhancing JET research capabilities. This paper provides an overview of the key design features of the ECT system and summarizes the main experimental results achieved so far.

Scaling Laws for the Multidimensional Burgers Equation with Quadratic External Potential

NASA Astrophysics Data System (ADS)

Leonenko, N. N.; Ruiz-Medina, M. D.

2006-07-01

The reordering of the multidimensional exponential quadratic operator in coordinate-momentum space (see X. Wang, C.H. Oh and L.C. Kwek (1998). J. Phys. A.: Math. Gen. 31:4329-4336) is applied to derive an explicit formulation of the solution to the multidimensional heat equation with quadratic external potential and random initial conditions. The solution to the multidimensional Burgers equation with quadratic external potential under Gaussian strongly dependent scenarios is also obtained via the Hopf-Cole transformation. The limiting distributions of scaling solutions to the multidimensional heat and Burgers equations with quadratic external potential are then obtained under such scenarios.

Lunar base heat pump, phase 1

NASA Technical Reports Server (NTRS)

Goldman, Jeffrey H.; Harvey, A.; Lovell, T.; Walker, David H.

1994-01-01

This report describes the Phase 1 process and analysis used to select a refrigerant and thermodynamic cycle as the basis of a vapor compression heat pump requiring a high temperature lift, then to perform a preliminary design to implement the selected concept, including major component selection. Use of a vapor compression heat pump versus other types was based on prior work performed for the Electric Power Research Institute. A high lift heat pump is needed to enable a thermal control system to remove heat down to 275 K from a habitable volume when the external thermal environment is severe. For example, a long-term lunar base habitat will reject heat from a space radiator to a 325 K environment. The first step in the selection process was to perform an optimization trade study, quantifying the effect of radiator operating temperature and heat pump efficiency on total system mass; then, select the radiator operating temperature corresponding to the lowest system mass. Total system mass included radiators, all heat pump components, and the power supply system. The study showed that lunar night operation, with no temperature lift, dictated the radiator size. To operate otherwise would require a high mass penalty to store power. With the defined radiation surface, and heat pump performances assumed to be from 40 percent to 60 percent of the Carnot ideal, the optimum heat rejection temperature ranged from 387 K to 377 K, as a function of heat pump performance. Refrigerant and thermodynamic cycles were then selected to best meet the previously determined design conditions. The system was then adapted as a ground-based prototype lifting temperature to 360 K (versus 385 K for flight unit) and using readily available commercial-grade components. Over 40 refrigerants, separated into wet and dry compression behavioral types, were considered in the selection process. Refrigerants were initially screened for acceptable critical temperature. The acceptable refrigerants were analyzed in ideal single and two-stage thermodynamic cycles. Top candidates were analyzed assuming realistic component limits and system pressure drops, and were evaluated for other considerations such as safety, environmental impact, and commercial availability. A maximum coefficient of performance (COP) of 56 percent of the Carnot ideal was achievable for a three-stage CFC-11 cycle operating under the flight conditions above. The program was completed by defining a control scheme and by researching and selecting the major components, compressor and heat exchangers, that could be used to implement the thermodynamic cycle selected. Special attention was paid to using similar technologies for the SIRF and flight heat pumps resulting in the commercially available equivalent of the flight unit. A package concept was generated for the components selected and mass and volume estimated.

Perforated fins effect on the heat transfer rate from a circular tube by using wind tunnel: An experimental view

NASA Astrophysics Data System (ADS)

Ahmadi Nadooshan, Afshin; Kalbasi, Rasool; Afrand, Masoud

2018-04-01

Perforated fins effects on the heat transfer rate of a circular tube are examined experimentally. An experimental system is set up through the wind tunnel and equipped with necessary measurement tools. Hot water passes through the finned tube and heat transfers to the fin-side air created using the wind tunnel with different velocities. Two fin sets of identical weight are installed on a circular tube with different outer diameters of 22 and 26 mm. The experiments are conducted at two different mass flow rates of the hot water and six Reynolds number of external air flow. Considering the four finned tubes and one no finned tube, a total of 60 tests are conducted. Results showed that with increasing the internal or external flow rates, the effect of larger cross-sectional area is greater. By opening holes on the fins, in addition to weight loss, the maximum heat transfer rate for perforated fins increases by 8.78% and 9.23% respectively for mass flow rates of 0.05 and 0.1 kg/s at low external Reynolds number. While, at high external Reynolds number, the holes reduces heat transfer by 8.4% and 10.6% for mass flow rates of 0.05 and 0.1 kg/s, respectively.

Development of an Operation Control System for Photovoltaics and Electric Storage Heaters for Houses Based on Information in Weather Forecasts

NASA Astrophysics Data System (ADS)

Obara, Shin'ya

An all-electric home using an electric storage heater with safety and cleaning is expanded. However, the general electric storage heater leads to an unpleasant room temperature and energy loss by the overs and shorts of the amount of heat radiation when the climate condition changes greatly. Consequently, the operation of the electric storage heater introduced into an all-electric home, a storage type electric water heater, and photovoltaics was planned using weather forecast information distributed by a communication line. The comfortable evaluation (the difference between a room-temperature target and a room-temperature result) when the proposed system was employed based on the operation planning, purchase electric energy, and capacity of photovoltaics was investigated. As a result, comfortable heating operation was realized by using weather forecast data; furthermore, it is expected that the purchase cost of the commercial power in daytime can be reduced by introducing photovoltaics. Moreover, when the capacity of the photovoltaics was increased, the surplus power was stored in the electric storage heater, but an extremely unpleasant room temperature was not shown in the investigation ranges of this paper. By obtaining weather information from the forecast of the day from an external service using a communication line, the heating system of the all-electric home with low energy loss and comfort temperature is realizable.

KSC-2011-6665

NASA Image and Video Library

2011-06-30

CAPE CANAVERAL, Fla. -- In the high bay of the RTG storage facility at NASA's Kennedy Space Center in Florida, the external and internal protective layers of the shipping cask are lifted away from the multi-mission radioisotope thermoelectric generator (MMRTG) for NASA's Mars Science Laboratory mission. The MMRTG no longer needs supplemental cooling since any excess heat generated can dissipate into the air in the high bay. The MMRTG will generate the power needed for the mission from the natural decay of plutonium-238, a non-weapons-grade form of the radioisotope. Heat given off by this natural decay will provide constant power through the day and night during all seasons. Waste heat from the MMRTG will be circulated throughout the rover system to keep instruments, computers, mechanical devices and communications systems within their operating temperature ranges. MSL's components include a compact car-sized rover, Curiosity, which has 10 science instruments designed to search for evidence on whether Mars has had environments favorable to microbial life, including chemical ingredients for life. The unique rover will use a laser to look inside rocks and release its gasses so that the rover’s spectrometer can analyze and send the data back to Earth. Launch of MSL aboard a United Launch Alliance Atlas V rocket is scheduled for Nov. 25 from Space Launch Complex 41 on Cape Canaveral Air Force Station in Florida. For more information, visit http://www.nasa.gov/msl. Photo credit: NASA/Frankie Martin

A Stirling engine for use with lower quality fuels

NASA Astrophysics Data System (ADS)

Paul, Christopher J.

There is increasing interest in using renewable fuels from biomass or alternative fuels such as municipal waste to reduce the need for fossil based fuels. Due to the lower heating values and higher levels of impurities, small scale electricity generation is more problematic. Currently, there are not many technologically mature options for small scale electricity generation using lower quality fuels. Even though there are few manufacturers of Stirling engines, the history of their development for two centuries offers significant guidance in developing a viable small scale generator set using lower quality fuels. The history, development, and modeling of Stirling engines were reviewed to identify possible model and engine configurations. A Stirling engine model based on the finite volume, ideal adiabatic model was developed. Flow dissipation losses are shown to need correcting as they increase significantly at low mean engine pressure and high engine speed. The complete engine including external components was developed. A simple yet effective method of evaluating the external heat transfer to the Stirling engine was created that can be used with any second order Stirling engine model. A derivative of the General Motors Ground Power Unit 3 was designed. By significantly increasing heater, cooler and regenerator size at the expense of increased dead volume, and adding a combustion gas recirculation, a generator set with good efficiency was designed.

24 CFR 3280.702 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-04-01

... means that portion of a refrigerated air cooling or (in the case of a heat pump) heating system which includes the refrigerant pump (compressor) and the external heat exchanger. Air conditioning evaporator section means a heat exchanger used to cool or (in the case of a heat pump) heat air for use in comfort...

Heat transfer and hydrodynamic analysis in an industrial circulating fluidized bed boiler

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

Di Maggio, T.; Piedfer, O.; Jestin, L.

In order to scale-up Circulating Fluidized Bed boilers (up to 600 MWe), Electricite de France has initiated a Research and Development program including: laboratory work on mock-up, numerical modeling and on-site tests in the 125 MWe CFB Emile Huchet plant. This paper is devoted to on-site measurements analysis in two main components of this industrial unit: the external fluidized bed heat exchangers and the backpass. This study particularly concerns hydrodynamics and heat transfer with the final target of developing a physical model of a CFB unit. The first part of this paper describes the specific instrumentation set up on externalmore » fluidized bed heat exchangers. The comparison between experimental data collected on these heat exchangers and the theoretical heat transfer models mainly used, shows a great difference about the value of the overall heat transfer coefficient. To explain this discrepancy, the particle flow pattern initially used in the thermal balance calculation is modified and a solid bypass is introduced. The analysis of the by-pass behavior, connected to the geometrical and operating parameters of each exchanger, confirms the particle flow pattern suggested. The second part of this paper shows an analysis of the specific measurements set up on the backpass to study heat transfer. The physical model of heat transfer used to assess the importance of each convection, radiation and conduction components is presented. This model allows one to assess the influence of heat exchangers design on heat transfer. Moreover, the analysis of heat transfer variations during sweeping cycles gives the amount of dust that is removed from the heat exchanger tubes. These results are used to evaluate the amount of power that can be recovered by optimizing both design and sweeping of the backpass.« less

Time-dependent photon heat transport through a mesoscopic Josephson device

NASA Astrophysics Data System (ADS)

Lu, Wen-Ting; Zhao, Hong-Kang

2017-02-01

The time-oscillating photon heat current through a dc voltage biased mesoscopic Josephson Junction (MJJ) has been investigated by employing the nonequilibrium Green's function approach. The Landauer-like formula of photon heat current has been derived in both of the Fourier space and its time-oscillating versions, where Coulomb interaction, self inductance, and magnetic flux take effective roles. Nonlinear behaviors are exhibited in the photon heat current due to the quantum nature of MJJ and applied external dc voltage. The magnitude of heat current decreases with increasing the external bias voltage, and subtle oscillation structures appear as the superposition of different photon heat branches. The overall period of heat current with respect to time is not affected by Coulomb interaction, however, the magnitude and phase of it vary considerably by changing the Coulomb interaction.

Global correlation between surface heat fluxes and insolation in the 11-year solar cycle: The latitudinal effect

NASA Astrophysics Data System (ADS)

Volobuev, D. M.; Makarenko, N. G.

2014-12-01

Because of the small amplitude of insolation variations (1365.2-1366.6 W m-2 or 0.1%) from the 11-year solar cycle minimum to the cycle maximum and the structural complexity of the climatic dynamics, it is difficult to directly observe a solar signal in the surface temperature. The main difficulty is reduced to two factors: (1) a delay in the temperature response to external action due to thermal inertia, and (2) powerful internal fluctuations of the climatic dynamics suppressing the solar-driven component. In this work we take into account the first factor, solving the inverse problem of thermal conductivity in order to calculate the vertical heat flux from the measured temperature near the Earth's surface. The main model parameter—apparent thermal inertia—is calculated from the local seasonal extremums of temperature and albedo. We level the second factor by averaging mean annual heat fluxes in a latitudinal belt. The obtained mean heat fluxes significantly correlate with a difference between the insolation and optical depth of volcanic aerosol in the atmosphere, converted into a hindered heat flux. The calculated correlation smoothly increases with increasing latitude to 0.4-0.6, and the revealed latitudinal dependence is explained by the known effect of polar amplification.

Production of ZrC Matrix for Use in Gas Fast Reactor Composite Fuels

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

Vasudevamurthy, Gokul; Knight, Travis W.; Roberts, Elwyn

2007-07-01

Zirconium carbide is being considered as a candidate for inert matrix material in composite nuclear fuel for Gas fast reactors due to its favorable characteristics. ZrC can be produced by the direct reaction of pure zirconium and graphite powders. Such a reaction is exothermic in nature. The reaction is self sustaining once initial ignition has been achieved. The heat released during the reaction is high enough to complete the reaction and achieve partial sintering without any external pressure applied. External heat source is required to achieve ignition of the reactants and maintain the temperature close to the adiabatic temperature tomore » achieve higher levels of sintering. External pressure is also a driving force for sintering. In the experiments described, cylindrical compacts of ZrC were produced by direct combustion reaction. External induction heating combined with varying amounts of external applied pressure was employed to achieve varying degrees of density/porosity. The effect of reactant particle size on the product characteristics was also studied. The samples were characterized for density/porosity, composition and microstructure. (authors)« less

A review of thermal performance improving methods of lithium ion battery: Electrode modification and thermal management system

NASA Astrophysics Data System (ADS)

Zhao, Rui; Zhang, Sijie; Liu, Jie; Gu, Junjie

2015-12-01

Lithium ion (Li-ion) battery has emerged as an important power source for portable devices and electric vehicles due to its superiority over other energy storage technologies. A mild temperature variation as well as a proper operating temperature range are essential for a Li-ion battery to perform soundly and have a long service life. In this review paper, the heat generation and dissipation of Li-ion battery are firstly analyzed based on the energy conservation equations, followed by an examination of the hazardous effects of an above normal operating temperature. Then, advanced techniques in respect of electrode modification and systematic battery thermal management are inspected in detail as solutions in terms of reducing internal heat production and accelerating external heat dissipation, respectively. Specifically, variable parameters like electrode thickness and particle size of active material, along with optimization methods such as coating, doping, and adding conductive media are discussed in the electrode modification section, while the current development in air cooling, liquid cooling, heat pipe cooling, and phase change material cooling systems are reviewed in the thermal management part as different ways to improve the thermal performance of Li-ion batteries.

Nanoencapsulation of phase change materials for advanced thermal energy storage systems

PubMed Central

Shchukina, E. M.; Graham, M.; Zheng, Z.

2018-01-01

Phase change materials (PCMs) allow the storage of large amounts of latent heat during phase transition. They have the potential to both increase the efficiency of renewable energies such as solar power through storage of excess energy, which can be used at times of peak demand; and to reduce overall energy demand through passive thermal regulation. 198.3 million tons of oil equivalent were used in the EU in 2013 for heating. However, bulk PCMs are not suitable for use without prior encapsulation. Encapsulation in a shell material provides benefits such as protection of the PCM from the external environment and increased specific surface area to improve heat transfer. This review highlights techniques for the encapsulation of both organic and inorganic PCMs, paying particular attention to nanoencapsulation (capsules with sizes <1 μm). We also provide insight on future research, which should focus on (i) the development of multifunctional shell materials to improve lifespan and thermal properties and (ii) advanced mass manufacturing techniques for the economically viable production of PCM capsules, making it possible to utilize waste heat in intelligent passive thermal regulation systems, employing controlled, “on demand” energy release/uptake. PMID:29658558

Nanoencapsulation of phase change materials for advanced thermal energy storage systems.

PubMed

Shchukina, E M; Graham, M; Zheng, Z; Shchukin, D G

2018-06-05

Phase change materials (PCMs) allow the storage of large amounts of latent heat during phase transition. They have the potential to both increase the efficiency of renewable energies such as solar power through storage of excess energy, which can be used at times of peak demand; and to reduce overall energy demand through passive thermal regulation. 198.3 million tons of oil equivalent were used in the EU in 2013 for heating. However, bulk PCMs are not suitable for use without prior encapsulation. Encapsulation in a shell material provides benefits such as protection of the PCM from the external environment and increased specific surface area to improve heat transfer. This review highlights techniques for the encapsulation of both organic and inorganic PCMs, paying particular attention to nanoencapsulation (capsules with sizes <1 μm). We also provide insight on future research, which should focus on (i) the development of multifunctional shell materials to improve lifespan and thermal properties and (ii) advanced mass manufacturing techniques for the economically viable production of PCM capsules, making it possible to utilize waste heat in intelligent passive thermal regulation systems, employing controlled, "on demand" energy release/uptake.

Electrically controllable twisted-coiled artificial muscle actuators using surface-modified polyester fibers

NASA Astrophysics Data System (ADS)

Park, Jungwoo; Yoo, Ji Wang; Seo, Hee Won; Lee, Youngkwan; Suhr, Jonghwan; Moon, Hyungpil; Koo, Ja Choon; Ryeol Choi, Hyouk; Hunt, Robert; Kim, Kwang Jin; Kim, Soo Hyun; Nam, Jae-Do

2017-03-01

As a new class of thermally activated actuators based on polymeric fibers, we investigated polyethylene terephthalate (PET) yarns for the development of a twisted-coiled polymer fiber actuator (TCA). The PET yarn TCA exhibited the maximum linear actuation up to 8.9% by external heating at above the glass transition temperature, 160 °C-180 °C. The payload of the actuator was successfully correlated with the preload and training-load conditions by an empirical equation. Furthermore, the PET-based TCA was electrically driven by Joule heating after the PET surface was metallization with silver. For the fast and precise control of PET yarn TCA, electroless silver plating was conducted to form electrical conductive layers on the PET fiber surface. The silver plated PET-based TCA was tested by Joule heating and the tensile actuation was increased up to 12.1% (6 V) due to the enhanced surface hardness and slippage of PET fibers. Overall, silver plating of the polymeric yarn provided a fast actuation speed and enhanced actuation performance of the TCA actuator by Joule heating, providing a great potential for being used in artificial muscle for biomimetic machines including robots, industrial actuators and powered exoskeletons.

Closed Brayton cycle power conversion systems for nuclear reactors :

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

Wright, Steven A.; Lipinski, Ronald J.; Vernon, Milton E.

2006-04-01

This report describes the results of a Sandia National Laboratories internally funded research program to study the coupling of nuclear reactors to gas dynamic Brayton power conversion systems. The research focused on developing integrated dynamic system models, fabricating a 10-30 kWe closed loop Brayton cycle, and validating these models by operating the Brayton test-loop. The work tasks were performed in three major areas. First, the system equations and dynamic models for reactors and Closed Brayton Cycle (CBC) systems were developed and implemented in SIMULINKTM. Within this effort, both steady state and dynamic system models for all the components (turbines, compressors,more » reactors, ducting, alternators, heat exchangers, and space based radiators) were developed and assembled into complete systems for gas cooled reactors, liquid metal reactors, and electrically heated simulators. Various control modules that use proportional-integral-differential (PID) feedback loops for the reactor and the power-conversion shaft speed were also developed and implemented. The simulation code is called RPCSIM (Reactor Power and Control Simulator). In the second task an open cycle commercially available Capstone C30 micro-turbine power generator was modified to provide a small inexpensive closed Brayton cycle test loop called the Sandia Brayton test-Loop (SBL-30). The Capstone gas-turbine unit housing was modified to permit the attachment of an electrical heater and a water cooled chiller to form a closed loop. The Capstone turbine, compressor, and alternator were used without modification. The Capstone systems nominal operating point is 1150 K turbine inlet temperature at 96,000 rpm. The annular recuperator and portions of the Capstone control system (inverter) and starter system also were reused. The rotational speed of the turbo-machinery is controlled by adjusting the alternator load by using the electrical grid as the load bank. The SBL-30 test loop was operated at the manufacturers site (Barber-Nichols Inc.) and installed and operated at Sandia. A sufficiently detailed description of the loop is provided in this report along with the design characteristics of the turbo-alternator-compressor set to allow other researchers to compare their results with those measured in the Sandia test-loop. The third task consisted of a validation effort. In this task the test loop was operated and compared with the modeled results to develop a more complete understanding of this electrically heated closed power generation system and to validate the model. The measured and predicted system temperatures and pressures are in good agreement, indicating that the model is a reasonable representation of the test loop. Typical deviations between the model and the hardware results are less than 10%. Additional tests were performed to assess the capability of the Brayton engine to continue to remove decay heat after the reactor/heater is shutdown, to develop safe and effective control strategies, and to access the effectiveness of gas inventory control as an alternative means to provide load following. In one test the heater power was turned off to simulate a rapid reactor shutdown, and the turbomachinery was driven solely by the sensible heat stored in the heater for over 71 minutes without external power input. This is an important safety feature for CBC systems as it means that the closed Brayton loop will keep cooling the reactor without the need for auxiliary power (other than that needed to circulate the waste heat rejection coolant) provided the heat sink is available.« less

Design, fabrication, and testing of an external fuel (UO2), full-length thermionic converter

NASA Technical Reports Server (NTRS)

Schock, A.; Raab, B.

1971-01-01

The development of a full-length external-fuel thermionic converter for in-pile testing is described. The development program includes out-of-pile performance testing of the fully fueled-converter, using RF-induction heating, before its installation in the in-pile test capsule. The external-fuel converter is cylindrical in shape, and consists of an inner, centrally cooled collector, and an outer emitter surrounded by nuclear fuel. The term full-length denotes that the converter is long enough to extend over the full height of the reactor core. Thus, the converter is not a scaled-down test device, but a full-scale fuel element of the thermionic reactor. The external-fuel converter concept permits a number of different design options, particularly with respect to the fuel composition and shape, and the collector cooling arrangement. The converter described was developed for the Jet Propulsion Laboratory, and is based on their concept for a thermionic reactor with uninsulated collector cooling as previously described. The converter is double-ended, with through-flow cooling, and with ceramic seals and emitter and collector power take-offs at both ends. The design uses a revolver-shaped tungsten emitter body, with the central emitter hole surrounded by six peripheral fuel holes loaded with cylindrical UO2 pellets.

Development of a Space-Flight ADR Providing Continuous Cooling at 50 Mk with Heat Rejection at 10 K

NASA Technical Reports Server (NTRS)

Tuttle, James; Canavan, Edgar; DeLee, Hudson; DiPirro, Michael; Jahromi, Amir; James, Byron; Kimball, Mark; Shirron, Peter; Sullivan, Dan; Switzer, Eric

2017-01-01

Future astronomical instruments will require sub-Kelvin detector temperatures to obtain high sensitivity. In many cases large arrays of detectors will be used, and the associated cooling systems will need performance surpassing the limits of present technologies. NASA is developing a compact cooling system that will lift heat continuously at temperatures below 50 mK and reject it at over 10 K. Based on Adiabatic Demagnetization Refrigerators (ADRs), it will have high thermodynamic efficiency and vibration-free operation with no moving parts. It will provide more than 10 times the current flight ADR cooling power at 50 mK and will also continuously cool a 4 K stage for instruments and optics. In addition, it will include an advanced magnetic shield resulting in external field variations below 5 T. We describe the cooling system here and report on the progress in its development.

2-D and 3-D mixing flow analyses of a scramjet-afterbody configuration

NASA Technical Reports Server (NTRS)

Baysal, Oktay; Eleshaky, Mohamed E.; Engelund, Walter C.

1989-01-01

A cold simulant gas study of propulsion/airframe integration for a hypersonic vehicle powered by a scramjet engine is presented. The specific heat ratio of the hot exhaust gases are matched by utilizing a cold mixture of argon and Freon-12. Solutions are obtained for a hypersonic corner flow and a supersonic rectangular flow in order to provide the upstream boundary conditions. The computational test examples also provide a comparison of this flow with that of air as the expanding supersonic jet, where the specific heats are assumed to be constant. It is shown that the three-dimensional computational fluid capabilities developed for these types of flow may be utilized to augment the conventional wind tunnel studies of scramjet afterbody flows using cold simulant exhaust gases, which in turn can help in the design of a scramjet internal-external nozzle.

Development of a Space-Flight ADR Providing Continuous Cooling at 50 mK with Heat Rejection at 10 K

NASA Technical Reports Server (NTRS)

Tuttle, Jim; Canavan, Ed; DeLee, Hudson; Dipirro, Michael; Jahromi, Amir; Kimball, Mark; Shirron, Peter; Sullivan, Dan; Switzer, Eric

2017-01-01

Future astronomical instruments will require sub-Kelvin detector temperatures to obtain high sensitivity. In many cases large arrays of detectors will be used, and the associated cooling systems will need performance surpassing the limits of present technologies. NASA is developing a compact cooling system that will lift heat continuously at temperatures below 50 mK and reject it at over 10 K. Based on Adiabatic Demagnetization Refrigerators (ADRs), it will have high thermodynamic efficiency and vibration-free operation with no moving parts. It will provide more than 10 times the current flight ADR cooling power at 50 mK and will also continuously cool a 4 K stage for instruments and optics. In addition, it will include an advanced magnetic shield resulting in external field variations below 5 T. We describe the cooling system here and report on the progress in its development.

Investigation of Factors Affecting Body Temperature Changes During Routine Clinical Head Magnetic Resonance Imaging

PubMed Central

Kim, Myeong Seong

2016-01-01

Background Pulsed radiofrequency (RF) magnetic fields, required to produce magnetic resonance imaging (MRI) signals from tissue during the MRI procedure have been shown to heat tissues. Objectives To investigate the relationship between body temperature rise and the RF power deposited during routine clinical MRI procedures, and to determine the correlation between this effect and the body’s physiological response. Patients and Methods We investigated 69 patients from the Korean national cancer center to identify the main factors that contribute to an increase in body temperature (external factors and the body’s response) during a clinical brain MRI. A routine protocol sequence of MRI scans (1.5 T and 3.0 T) was performed. The patient’s tympanic temperature was recorded before and immediately after the MRI procedure and compared with changes in variables related to the body’s physiological response to heat. Results Our investigation of the physiological response to RF heating indicated a link between increasing age and body temperature. A higher increase in body temperature was observed in older patients after a 3.0-T MRI (r = 0.07, P = 0.29 for 1.5-T MRI; r = 0.45, P = 0.002 for 3.0-T MRI). The relationship between age and body heat was related to the heart rate (HR) and changes in HR during the MRI procedure; a higher RF power combined with a reduction in HR resulted in an increase in body temperature. Conclusion A higher magnetic field strength and a decrease in the HR resulted in an increase in body temperature during the MRI procedure. PMID:27895872

Field Testing of Cryogenic Carbon Capture

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

Sayre, Aaron; Frankman, Dave; Baxter, Andrew

Sustainable Energy Solutions has been developing Cryogenic Carbon Capture™ (CCC) since 2008. In that time two processes have been developed, the External Cooling Loop and Compressed Flue Gas Cryogenic Carbon Capture processes (CCC ECL™ and CCC CFG™ respectively). The CCC ECL™ process has been scaled up to a 1TPD CO2 system. In this process the flue gas is cooled by an external refrigerant loop. SES has tested CCC ECL™ on real flue gas slip streams from subbituminous coal, bituminous coal, biomass, natural gas, shredded tires, and municipal waste fuels at field sites that include utility power stations, heating plants, cementmore » kilns, and pilot-scale research reactors. The CO2 concentrations from these tests ranged from 5 to 22% on a dry basis. CO2 capture ranged from 95-99+% during these tests. Several other condensable species were also captured including NO2, SO2 and PMxx at 95+%. NO was also captured at a modest rate. The CCC CFG™ process has been scaled up to a .25 ton per day system. This system has been tested on real flue gas streams including subbituminous coal, bituminous coal and natural gas at field sites that include utility power stations, heating plants, and pilot-scale research reactors. CO2 concentrations for these tests ranged from 5 to 15% on a dry basis. CO2 capture ranged from 95-99+% during these tests. Several other condensable species were also captured including NO2, SO2 and PMxx at 95+%. NO was also captured at 90+%. Hg capture was also verified and the resulting effluent from CCC CFG™ was below a 1ppt concentration. This paper will focus on discussion of the capabilities of CCC, the results of field testing and the future steps surrounding the development of this technology.« less

Thermoelectric power generator with intermediate loop

DOEpatents

Bell, Lon E; Crane, Douglas Todd

2013-05-21

A thermoelectric power generator is disclosed for use to generate electrical power from heat, typically waste heat. An intermediate heat transfer loop forms a part of the system to permit added control and adjustability in the system. This allows the thermoelectric power generator to more effectively and efficiently generate power in the face of dynamically varying temperatures and heat flux conditions, such as where the heat source is the exhaust of an automobile, or any other heat source with dynamic temperature and heat flux conditions.

Thermoelectric power generator with intermediate loop

DOEpatents

Bel,; Lon, E [Altadena, CA; Crane, Douglas Todd [Pasadena, CA

2009-10-27

A thermoelectric power generator is disclosed for use to generate electrical power from heat, typically waste heat. An intermediate heat transfer loop forms a part of the system to permit added control and adjustability in the system. This allows the thermoelectric power generator to more effectively and efficiently generate power in the face of dynamically varying temperatures and heat flux conditions, such as where the heat source is the exhaust of an automobile, or any other heat source with dynamic temperature and heat flux conditions.

A Thermoelectric Waste-Heat-Recovery System for Portland Cement Rotary Kilns

NASA Astrophysics Data System (ADS)

Luo, Qi; Li, Peng; Cai, Lanlan; Zhou, Pingwang; Tang, Di; Zhai, Pengcheng; Zhang, Qingjie

2015-06-01

Portland cement is produced by one of the most energy-intensive industrial processes. Energy consumption in the manufacture of Portland cement is approximately 110-120 kWh ton-1. The cement rotary kiln is the crucial equipment used for cement production. Approximately 10-15% of the energy consumed in production of the cement clinker is directly dissipated into the atmosphere through the external surface of the rotary kiln. Innovative technology for energy conservation is urgently needed by the cement industry. In this paper we propose a novel thermoelectric waste-heat-recovery system to reduce heat losses from cement rotary kilns. This system is configured as an array of thermoelectric generation units arranged longitudinally on a secondary shell coaxial with the rotary kiln. A mathematical model was developed for estimation of the performance of waste heat recovery. Discussions mainly focus on electricity generation and energy saving, taking a Φ4.8 × 72 m cement rotary kiln as an example. Results show that the Bi2Te3-PbTe hybrid thermoelectric waste-heat-recovery system can generate approximately 211 kW electrical power while saving 3283 kW energy. Compared with the kiln without the thermoelectric recovery system, the kiln with the system can recover more than 32.85% of the energy that used to be lost as waste heat through the kiln surface.

Heat-driven liquid metal cooling device for the thermal management of a computer chip

NASA Astrophysics Data System (ADS)

Ma, Kun-Quan; Liu, Jing

2007-08-01

The tremendous heat generated in a computer chip or very large scale integrated circuit raises many challenging issues to be solved. Recently, liquid metal with a low melting point was established as the most conductive coolant for efficiently cooling the computer chip. Here, by making full use of the double merits of the liquid metal, i.e. superior heat transfer performance and electromagnetically drivable ability, we demonstrate for the first time the liquid-cooling concept for the thermal management of a computer chip using waste heat to power the thermoelectric generator (TEG) and thus the flow of the liquid metal. Such a device consumes no external net energy, which warrants it a self-supporting and completely silent liquid-cooling module. Experiments on devices driven by one or two stage TEGs indicate that a dramatic temperature drop on the simulating chip has been realized without the aid of any fans. The higher the heat load, the larger will be the temperature decrease caused by the cooling device. Further, the two TEGs will generate a larger current if a copper plate is sandwiched between them to enhance heat dissipation there. This new method is expected to be significant in future thermal management of a desk or notebook computer, where both efficient cooling and extremely low energy consumption are of major concern.

Analysis of self-heating of thermally assisted spin-transfer torque magnetic random access memory

DOE PAGES

Deschenes, Austin; Muneer, Sadid; Akbulut, Mustafa; ...

2016-11-11

Thermal assistance has been shown to significantly reduce the required operation power for spin torque transfer magnetic random access memory (STT-MRAM). Proposed heating methods include modified material stack compositions that result in increased self-heating or external heat sources. Here, we analyze the self-heating process of a standard perpendicular magnetic anisotropy STT-MRAM device through numerical simulations in order to understand the relative contributions of Joule, thermoelectric Peltier and Thomson, and tunneling junction heating. A 2D rotationally symmetric numerical model is used to solve the coupled electro-thermal equations including thermoelectric effects and heat absorbed or released at the tunneling junction. We comparemore » self-heating for different common passivation materials, positive and negative electrical current polarity, and different device thermal anchoring and boundaries resistance configurations. The variations considered are found to result in significant differences in maximum temperatures reached. Average increases of 3 K, 10 K, and 100 K for different passivation materials, positive and negative polarity, and different thermal anchoring configurations, respectively, are observed. Furthermore, the highest temperatures, up to 424 K, are obtained for silicon dioxide as the passivation material, positive polarity, and low thermal anchoring with thermal boundary resistance configurations. Interestingly it is also found that due to the tunneling heat, Peltier effect, device geometry, and numerous interfacial layers around the magnetic tunnel junction (MTJ), most of the heat is dissipated on the lower potential side of the magnetic junction. We have observed this asymmetry in heating and is important as thermally assisted switching requires heating of the free layer specifically and this will be significantly different for the two polarity operations, set and reset.« less

High Tc Superconducting Magnet Excited by a Semiconductor Thermoelectric Element

NASA Astrophysics Data System (ADS)

Kuriyama, T.; Ono, M.; Tabe, S.; Oguchi, A.; Okamura, T.

2006-04-01

A high Tc superconducting (HTS) magnet excited by a thermal electromotive force of a thermoelectric element is studied. This HTS magnet has the advantages of compactness, lightweight and continuous excitation in comparison with conventional HTS magnets, because this HTS magnet does not need a large external power source. In this system, a heat input into the cryogenic environment is necessary to excite the thermoelectric element for constant operation. This heat generation, however, causes a rise in temperature of an HTS coil and reduces the system performance. In this paper, a newly designed magnet system which adopted a two-stage GM cryocooler was investigated. It enabled us to control the temperature of a thermoelectric element and that of an HTS coil independently. The temperature of the HTS coil could be kept at 10-20 K at the second stage of the GM cryocooler, while the thermoelectric element could be excited at higher temperature in the range of 50-70 K at the first stage, where the performance of the thermoelectric element was higher. The experimental results on this HTS magnet are shown and the possibility of the thermoelectric element as a main power source of the HTS magnets is discussed.

Active thermal control systems for lunar and Martian exploration

NASA Technical Reports Server (NTRS)

Ewert, Michael K.; Petete, Patricia A.; Dzenitis, John

1990-01-01

Several ATCS options including heat pumps, radiator shading devices, and single-phase flow loops were considered. The ATCS chosen for both lunar and Martian habitats consists of a heat pump integral with a nontoxic fluid acquisition and transport loop, and vertically oriented modular reflux-boiler radiators. The heat pump operates only during the lunar day. The lunar and Martian transfer vehicles have an internal single-phase water-acquisition loop and an external two-phase ammonia rejection system with rotating inflatable radiators. The lunar and Martian excursion vehicles incorporate internal single-phase water acquisition, which is connected via heat exchangers to external body-mounted single-phase radiators. A water evaporation system is used for the transfer vehicles during periods of high heating.

78 FR 18253 - Request for Information on Evaluating New Products for the Battery Chargers and External Power...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-03-26

... Information on Evaluating New Products for the Battery Chargers and External Power Supply Rulemaking AGENCY... classes of battery chargers and external power supplies. Specifically, DOE seeks information on battery...) standards that became effective on February 1, 2013. DOE is actively reviewing battery chargers that have...

Controlling the Internal Heat Transfer Coefficient by the Characteristics of External Flows

NASA Astrophysics Data System (ADS)

Zhuromskii, V. M.

2018-01-01

The engineering-physical fundamentals of substance synthesis in a boiling apparatus are presented. We have modeled a system of automatic stabilization of the maximum internal heat transfer coefficient in such an apparatus by the characteristics of external flows on the basis of adaptive seeking algorithms. The results of operation of the system in the shop are presented.

Heat transfer in a one-dimensional harmonic crystal in a viscous environment subjected to an external heat supply

NASA Astrophysics Data System (ADS)

Gavrilov, S. N.; Krivtsov, A. M.; Tsvetkov, D. V.

2018-05-01

We consider unsteady heat transfer in a one-dimensional harmonic crystal surrounded by a viscous environment and subjected to an external heat supply. The basic equations for the crystal particles are stated in the form of a system of stochastic differential equations. We perform a continualization procedure and derive an infinite set of linear partial differential equations for covariance variables. An exact analytic solution describing unsteady ballistic heat transfer in the crystal is obtained. It is shown that the stationary spatial profile of the kinetic temperature caused by a point source of heat supply of constant intensity is described by the Macdonald function of zero order. A comparison with the results obtained in the framework of the classical heat equation is presented. We expect that the results obtained in the paper can be verified by experiments with laser excitation of low-dimensional nanostructures.

Microlith-Based Catalytic Reactor for Air Quality and Trace Contaminant Control Applications

NASA Technical Reports Server (NTRS)

Vilekar, Saurabh; Hawley, Kyle; Junaedi, Christian; Crowder, Bruce; Prada, Julian; Mastanduno, Richard; Perry, Jay L.; Kayatin, Matthew J.

2015-01-01

Traditionally, gaseous compounds such as methane, carbon monoxide, and trace contaminants have posed challenges for maintaining clean air in enclosed spaces such as crewed spacecraft cabins as they are hazardous to humans and are often difficult to remove by conventional adsorption technology. Catalytic oxidizers have provided a reliable and robust means of disposing of even trace levels of these compounds by converting them into carbon dioxide and water. Precision Combustion, Inc. (PCI) and NASA - Marshall (MSFC) have been developing, characterizing, and optimizing high temperature catalytic oxidizers (HTCO) based on PCI's patented Microlith® technology to meet the requirements of future extended human spaceflight explorations. Current efforts have focused on integrating the HTCO unit with a compact, simple recuperative heat exchanger to reduce the overall system size and weight while also reducing its energy requirements. Previous efforts relied on external heat exchangers to recover the waste heat and recycle it to the oxidizer to minimize the system's power requirements; however, these units contribute weight and volume burdens to the overall system. They also result in excess heat loss due to the separation of the HTCO and the heat recuperator, resulting in lower overall efficiency. Improvements in the recuperative efficiency and close coupling of HTCO and heat recuperator lead to reductions in system energy requirements and startup time. Results from testing HTCO units integrated with heat recuperators at a variety of scales for cabin air quality control and heat melt compactor applications are reported and their benefits over previous iterations of the HTCO and heat recuperator assembly are quantified in this paper.

Low Emission AMTEC Automotive Power System. Final report for Department of Energy Contract DE-FG02-94ER81696

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

Hunt, Thomas K.

2001-04-17

This program investigated the potential for Alkali Metal Thermal to Electric Converter (AMTEC) technology to be useful in automotive power system applications. AMTEC, a thermally regenerative electrochemical energy conversion system, converts heat into electricity from a heat source at 750 C to 850 C and a radiator at 200 C to 350 C. AMTEC uses external combustion with correspondingly low emission of NO{sub x} and hydrocarbons, and can tolerate essentially any hydrocarbon fuel. Efficiencies of 20% to 30% are projected to be feasible for systems of 25 kWe to 40 kWe peak output. The research program has shown that theremore » are significant advantages to be achieved if AMTEC systems can be made cost effective for vehicle applications. Among these are (1) higher efficiency at part load than IC engines can yield, (2) omnifuel capability, and (3) low noise and low emission of pollutants. Demonstrated lifetimes already above 12,000 hours should be adequate for most vehicle applications. In major production, AMTEC costs are projected to reach $1/Watt, a value still too high for widespread automotive main power application. AMTEC's unique capabilities for low emissions, all-fuel operation, and insensitivity to ambient temperature, however, do make it a potential option for specialized vehicle applications needing these properties.« less

Sunlight Responsive Thermochromic Window System

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

Millett, F,A; Byker,H, J

2006-10-27

Pleotint has embarked on a novel approach with our Sunlight Responsive Thermochromic, SRT™, windows. We are integrating dynamic sunlight control, high insulation values and low solar heat gain together in a high performance window. The Pleotint SRT window is dynamic because it reversibly changes light transmission based on thermochromics activated directly by the heating effect of sunlight. We can achieve a window package with low solar heat gain coefficient (SHGC), a low U value and high insulation. At the same time our windows provide good daylighting. Our innovative window design offers architects and building designers the opportunity to choose theirmore » desired energy performance, excellent sound reduction, external pane can be self-cleaning, or a resistance to wind load, blasts, bullets or hurricanes. SRT windows would provide energy savings that are estimated at up to 30% over traditional window systems. Glass fabricators will be able to use existing equipment to make the SRT window while adding value and flexibility to the basic design. Glazing installers will have the ability to fit the windows with traditional methods without wires, power supplies and controllers. SRT windows can be retrofit into existing buildings,« less

Lithium-Metal Infused Trenches: Progress toward a Divertor Solution

NASA Astrophysics Data System (ADS)

Ruzic, D. N.; Fiflis, P.; Christenson, M.; Szott, M.; Xu, W.; Jung, S.; Morgan, T. W.; Kalathiparambil, K.

2014-10-01

The application of liquid metal, especially liquid lithium, as a plasma facing component (PFC) has the capacity to offer a strong alternative to solid PFCs by reducing damage concerns and enhancing plasma performance. The Liquid-Metal Infused Trenches (LiMIT) concept is a liquid metal divertor alternative which employs thermoelectric current from either plasma or external heating in tandem with the toroidal field to self-propel liquid lithium through a series of trenches. LiMIT has been tested in several devices, namely HT-7, the UIUC SLiDE and TELS facilities and Magnum PSI at heat fluxes of up to 3 MW/m-2. Results of these experiments, including velocity and temperature measurements, power handling considerations, and preliminary vapor shielding results will be discussed, focusing on the 117 shots performed at Magnum scanning magnetic fields and heat fluxes up to ~ 0.3 T and 3 MW/m-2. Concerns over tritium retention and MHD droplet ejection will additionally be addressed. LiMIT has also been proposed to function as a limiter on the EAST moveable limiter arm and tests have been performed with a prototype module inclined at various angles.

External heating of electrical cables and auto-ignition investigation.

PubMed

Courty, L; Garo, J P

2017-01-05

Electric cables are now extensively used for both residential and industrial applications. During more than twenty years, multi-scale approaches have been developed to study fire behavior of such cables that represents a serious challenge. Cables are rather complicated materials because they consist of an insulated part and jacket of polymeric materials. These polymeric materials can have various chemical structures, thicknesses and additives and generally have a char-forming tendency when exposed to heat source. In this work, two test methods are used for the characterization of cable pyrolysis and flammability. The first one permits the investigation of cable pyrolysis. A description of the cable mass loss is obtained, coupling an Arrhenius expression with a 1D thermal model of cables heating. Numerical results are successfully compared with experimental data obtained for two types of cable commonly used in French nuclear power plants. The second one is devoted to ignition investigations (spontaneous or piloted) of these cables. All these basic observations, measurements and modelling efforts are of major interest for a more comprehensive fire resistance evaluation of electric cables. Copyright © 2016 Elsevier B.V. All rights reserved.

Negative hydrogen ion production in a helicon plasma source

NASA Astrophysics Data System (ADS)

Santoso, J.; Manoharan, R.; O'Byrne, S.; Corr, C. S.

2015-09-01

In order to develop very high energy (>1 MeV) neutral beam injection systems for applications, such as plasma heating in fusion devices, it is necessary first to develop high throughput negative ion sources. For the ITER reference source, this will be realised using caesiated inductively coupled plasma devices, containing either hydrogen or deuterium discharges, operated with high rf input powers (up to 90 kW per driver). It has been suggested that due to their high power coupling efficiency, helicon devices may be able to reduce power requirements and potentially obviate the need for caesiation due to the high plasma densities achievable. Here, we present measurements of negative ion densities in a hydrogen discharge produced by a helicon device, with externally applied DC magnetic fields ranging from 0 to 8.5 mT at 5 and 10 mTorr fill pressures. These measurements were taken in the magnetised plasma interaction experiment at the Australian National University and were performed using the probe-based laser photodetachment technique, modified for the use in the afterglow of the plasma discharge. A peak in the electron density is observed at ˜3 mT and is correlated with changes in the rf power transfer efficiency. With increasing magnetic field, an increase in the negative ion fraction from 0.04 to 0.10 and negative ion densities from 8 × 1014 m-3 to 7 × 1015 m-3 is observed. It is also shown that the negative ion densities can be increased by a factor of 8 with the application of an external DC magnetic field.

Effect of thermal and thermo-mechanical cycling on the boron segregation behavior in the coarse-grained heat-affected zone of low-alloy steel

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

Kim, Sanghoon; Kang, Yongjoon; Lee, Changhee, E-mail: chlee@hanyang.ac.kr

The boron segregation behavior in the coarse-grained heat-affected zone (CGHAZ) of 10 ppm boron-added low-alloy steel during the welding cycle was investigated by taking the changes in the microstructure and hardness into account. Various CGHAZs were simulated with a Gleeble system as a function of the heat input and external stress, and the boron segregation behavior was analyzed by secondary ion mass spectrometry (SIMS) and particle tracking autoradiography (PTA). The segregation of boron was found to initially increase, and then decrease with an increase in the heat input. This is believed to be due to the back-diffusion of boron withmore » an increase in the exposure time at high temperature after non-equilibrium grain boundary segregation. The grain boundary segregation of boron could be decreased by an external stress applied during the welding cycle. Such behavior may be due to an increase in the grain boundary area as a result of the grain size reduction induced by the external stress. - Highlights: • Boron segregation behavior in the CGHAZ of low-alloy steel during a welding cycle was investigated. • Various CGHAZs were simulated with a Gleeble system as a function of the heat input and external stress. • Boron segregation behavior was analyzed using SIMS and PTA techniques.« less

Flexible power fabrics made of carbon nanotubes for harvesting thermoelectricity.

PubMed

Kim, Suk Lae; Choi, Kyungwho; Tazebay, Abdullah; Yu, Choongho

2014-03-25

Thermoelectric energy conversion is very effective in capturing low-grade waste heat to supply electricity particularly to small devices such as sensors, wireless communication units, and wearable electronics. Conventional thermoelectric materials, however, are often inadequately brittle, expensive, toxic, and heavy. We developed both p- and n-type fabric-like flexible lightweight materials by functionalizing the large surfaces and junctions in carbon nanotube (CNT) mats. The poor thermopower and only p-type characteristics of typical CNTs have been converted into both p- and n-type with high thermopower. The changes in the electronic band diagrams of the CNTs were experimentally investigated, elucidating the carrier type and relatively large thermopower values. With our optimized device design to maximally utilize temperature gradients, an electrochromic glucose sensor was successfully operated without batteries or external power supplies, demonstrating self-powering capability. While our fundamental study provides a method of tailoring electronic transport properties, our device-level integration shows the feasibility of harvesting electrical energy by attaching the device to even curved surfaces like human bodies.

Heat supply from municipal solid waste incineration plants in Japan: Current situation and future challenges.

PubMed

Tabata, Tomohiro; Tsai, Peii

2016-02-01

The use of waste-to-energy technology as part of a municipal solid waste management strategy could reduce the use of fossil fuels and contribute to prevention of global warming. In this study, we examined current heat and electricity production by incineration plants in Japan for external use. Herein, we discuss specific challenges to the promotion of heat utilisation and future municipal solid waste management strategies. We conducted a questionnaire survey to determine the actual conditions of heat production by incineration plants. From the survey results, information of about 498 incineration plants was extracted. When we investigated the relationship between heat production for external use and population density where incineration plants were located, we found that regions with a population density <1000 persons (km(2))(-1) produce <500 MJ t(-1) of heat. We also found that external use of such energy for factories, markets, and related use, was noted in cities with a population density of 2000 to 4000 persons (km(2))(-1). Several incineration plants have poor performance for heat production because there are few facilities near them to provide demand for the energy. This is the result of redundant capacity, and is reflected in the heat production performance. Given these results, we discussed future challenges to creating energy demand around incineration plants where there is presently none. We also examined the challenges involved in increasing heat supply beyond the present situation. © The Author(s) 2015.

Technique of optimization of minimum temperature driving forces in the heaters of regeneration system of a steam turbine unit

NASA Astrophysics Data System (ADS)

Shamarokov, A. S.; Zorin, V. M.; Dai, Fam Kuang

2016-03-01

At the current stage of development of nuclear power engineering, high demands on nuclear power plants (NPP), including on their economy, are made. In these conditions, improving the quality of NPP means, in particular, the need to reasonably choose the values of numerous managed parameters of technological (heat) scheme. Furthermore, the chosen values should correspond to the economic conditions of NPP operation, which are postponed usually a considerable time interval from the point of time of parameters' choice. The article presents the technique of optimization of controlled parameters of the heat circuit of a steam turbine plant for the future. Its particularity is to obtain the results depending on a complex parameter combining the external economic and operating parameters that are relatively stable under the changing economic environment. The article presents the results of optimization according to this technique of the minimum temperature driving forces in the surface heaters of the heat regeneration system of the steam turbine plant of a K-1200-6.8/50 type. For optimization, the collector-screen heaters of high and low pressure developed at the OAO All-Russia Research and Design Institute of Nuclear Power Machine Building, which, in the authors' opinion, have the certain advantages over other types of heaters, were chosen. The optimality criterion in the task was the change in annual reduced costs for NPP compared to the version accepted as the baseline one. The influence on the decision of the task of independent variables that are not included in the complex parameter was analyzed. An optimization task was decided using the alternating-variable descent method. The obtained values of minimum temperature driving forces can guide the design of new nuclear plants with a heat circuit, similar to that accepted in the considered task.

James Webb Space Telescope Integrated Science Instrument Module Calibration and Verification of High-Accuracy Instrumentation to Measure Heat Flow in Cryogenic Testing

NASA Technical Reports Server (NTRS)

Comber, Brian; Glazer, Stuart

2012-01-01

The James Webb Space Telescope (JWST) is an upcoming flagship observatory mission scheduled to be launched in 2018. Three of the four science instruments are passively cooled to their operational temperature range of 36K to 40K, and the fourth instrument is actively cooled to its operational temperature of approximately 6K. The requirement for multiple thermal zoned results in the instruments being thermally connected to five external radiators via individual high purity aluminum heat straps. Thermal-vacuum and thermal balance testing of the flight instruments at the Integrated Science Instrument Module (ISIM) element level will take place within a newly constructed shroud cooled by gaseous helium inside Goddard Space Flight Center's (GSFC) Space environment Simulator (SES). The flight external radiators are not available during ISIM-level thermal vacuum/thermal testing, so they will be replaced in test with stable and adjustable thermal boundaries with identical physical interfaces to the flight radiators. Those boundaries are provided by specially designed test hardware which also measures the heat flow within each of the five heat straps to an accuracy of less than 2 mW, which is less than 5% of the minimum predicted heat flow values. Measurement of the heat loads to this accuracy is essential to ISIM thermal model correlation, since thermal models are more accurately correlated when temperature data is supplemented by accurate knowledge of heat flows. It also provides direct verification by test of several high-level thermal requirements. Devices that measure heat flow in this manner have historically been referred to a "Q-meters". Perhaps the most important feature of the design of the JWST Q-meters is that it does not depend on the absolute accuracy of its temperature sensors, but rather on knowledge of precise heater power required to maintain a constant temperature difference between sensors on two stages, for which a table is empirically developed during a calibration campaign in a small chamber at GSFC. This paper provides a brief review of Q-meter design, and discusses the Q-meter calibration procedure including calibration chamber modifications and accommodations, handling of differing conditions between calibration and usage, the calibration process itself, and the results of the tests used to determine if the calibration is successful.

Laminated insulators having heat dissipation means

DOEpatents

Niemann, R.C.; Mataya, K.F.; Gonczy, J.D.

1980-04-24

A laminated body is provided with heat dissipation capabilities. The insulator body is formed by dielectric layers interleaved with heat conductive layers, and bonded by an adhesive to form a composite structure. The heat conductive layers include provision for connection to an external thermal circuit.

Transesterification of waste vegetable oil under pulse sonication using ethanol, methanol and ethanol-methanol mixtures.

PubMed

Martinez-Guerra, Edith; Gude, Veera Gnaneswar

2014-12-01

This study reports on the effects of direct pulse sonication and the type of alcohol (methanol and ethanol) on the transesterification reaction of waste vegetable oil without any external heating or mechanical mixing. Biodiesel yields and optimum process conditions for the transesterification reaction involving ethanol, methanol, and ethanol-methanol mixtures were evaluated. The effects of ultrasonic power densities (by varying sample volumes), power output rates (in W), and ultrasonic intensities (by varying the reactor size) were studied for transesterification reaction with ethanol, methanol and ethanol-methanol (50%-50%) mixtures. The optimum process conditions for ethanol or methanol based transesterification reaction of waste vegetable oil were determined as: 9:1 alcohol to oil ratio, 1% wt. catalyst amount, 1-2 min reaction time at a power output rate between 75 and 150 W. It was shown that the transesterification reactions using ethanol-methanol mixtures resulted in biodiesel yields as high as >99% at lower power density and ultrasound intensity when compared to ethanol or methanol based transesterification reactions. Copyright © 2014 Elsevier Ltd. All rights reserved.

Convective hydromagnetic instabilities of a power-law liquid saturating a porous medium: Flux conditions

NASA Astrophysics Data System (ADS)

Chahtour, C.; Ben Hamed, H.; Beji, H.; Guizani, A.; Alimi, W.

2018-01-01

We investigate how an external imposed magnetic field affects thermal instability in a horizontal shallow porous cavity saturated by a non-Newtonian power-law liquid. The magnetic field is assumed to be constant and parallel to the gravity. A uniform heat flux is applied to the horizontal walls of the layer while the vertical walls are adiabatic. We use linear stability analysis to find expressions for the critical Rayleigh number as a function of the power-law index and the intensity of the magnetic field. We use nonlinear parallel flow theory to find some explicit solutions of the problem, and we use finite difference numerical simulations to solve the full nonlinear equations. We show how the presence of magnetic field alters the known hydrodynamical result of Newtonian flows and power-law flows and how it causes the presence of subcritical finite amplitude convection for both pseudoplastic and dilatant fluids. We also show that in the limit of very strong magnetic field, the dissipation of energy by Joule effect dominates the dissipation of energy by shear stress and gives to the liquid an inviscid character.

High performance terahertz metasurface quantum-cascade VECSEL with an intra-cryostat cavity

DOE PAGES

Xu, Luyao; Curwen, Christopher A.; Reno, John L.; ...

2017-09-04

A terahertz quantum-cascade (QC) vertical-external-cavity surface-emitting-laser (VECSEL) is demonstrated with over 5 mW power in continuous-wave and single-mode operation above 77 K, in combination with a near-Gaussian beam pattern with full-width half-max divergence as narrow as ~5° × 5°, with no evidence of thermal lensing. This is realized by creating an intra-cryostat VECSEL cavity to reduce the cavity loss and designing an active focusing metasurface reflector with low power dissipation for efficient heat removal. Compared with a conventional quantumcascade laser based on a metal-metal waveguide, the intra-cryostat QC-VECSEL exhibits significant improvements in both output power level and beam pattern. Also,more » the intra-cryostat configuration newly allows evaluation of QC-VECSEL operation vs. temperature, showing a maximum pulsed mode operating temperature of 129 K. While the threshold current density in the QC-VECSEL is worse in comparison to a conventional edge-emitting metal-metal waveguide QClaser, the beam quality, slope efficiency, maximum power, and thermal resistance are all significantly improved.« less

Design and Preliminary Thermal Performance of the Mars Science Laboratory Rover Heat Exchangers

NASA Technical Reports Server (NTRS)

Mastropietro, A. J.; Beatty, John; Kelly, Frank; Birur, Gajanana; Bhandari, Pradeep; Pauken, Michael; Illsley, Peter; Liu, Yuanming; Bame, David; Miller, Jennifer

2010-01-01

The challenging range of proposed landing sites for the Mars Science Laboratory Rover requires a rover thermal management system that is capable of keeping temperatures controlled across a wide variety of environmental conditions. On the Martian surface where temperatures can be as cold as -123 degrees Centigrade and as warm as 38 degrees Centigrade, the Rover relies upon a Mechanically Pumped Fluid Loop (MPFL) and external radiators to maintain the temperature of sensitive electronics and science instruments within a -40 degrees Centigrade to 50 degrees Centigrade range. The MPFL also manages significant waste heat generated from the Rover power source, known as the Multi Mission Radioisotope Thermoelectric Generator (MMRTG). The MMRTG produces 110 Watts of electrical power while generating waste heat equivalent to approximately 2000 Watts. Two similar Heat Exchanger (HX) assemblies were designed to both acquire the heat from the MMRTG and radiate waste heat from the onboard electronics to the surrounding Martian environment. Heat acquisition is accomplished on the interior surface of each HX while heat rejection is accomplished on the exterior surface of each HX. Since these two surfaces need to be at very different temperatures in order for the MPFL to perform efficiently, they need to be thermally isolated from one another. The HXs were therefore designed for high in-plane thermal conductivity and extremely low through-thickness thermal conductivity by using aerogel as an insulator inside composite honeycomb sandwich panels. A complex assembly of hand welded and uniquely bent aluminum tubes are bonded onto the HX panels and were specifically designed to be easily mated and demated to the rest of the Rover Heat Recovery and Rejection System (RHRS) in order to ease the integration effort. During the cruise phase to Mars, the HX assemblies serve the additional function of transferring heat from the Rover MPFL to the separate Cruise Stage MPFL so that heat generated deep inside the Rover can be dissipated via the Cruise Stage radiators. Significant fabrication challenges had to be overcome in order to make the HX design a reality. The cruise phase thermal performance of the Rover HXs was verified in the cruise phase system level thermal vacuum test that was performed at JPL in January of 2009. The Rover HXs were modeled in I-DEAS TMG and predictions are compared to actual data from the test.

Automotive Stirling reference engine design report

NASA Technical Reports Server (NTRS)

1981-01-01

The reference Stirling engine system is described which provides the best possible fuel economy while meeting or exceeding all other program objectives. The system was designed to meet the requirements of a 1984 Pontiac Phoenix (X-body). This design utilizes all new technology that can reasonably be expected to be developed by 1984 and that is judged to provide significant improvement, relative to development risk and cost. Topics covered include: (1) external heat system; (2) hot engine system; (3) cold engine system; (4) engine drive system; (5) power control system and auxiliaries; (6) engine instalation; (7) optimization and vehicle simulation; (8) engine materials; and (9) production cost analysis.

Note: A microfluidic freezer based on evaporative cooling of atomized aqueous microdroplets

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

Song, Jin; Kim, Dohyun, E-mail: dohyun.kim@mju.ac.kr; Chung, Minsub

2015-01-15

We report for the first time water-based evaporative cooling integrated into a microfluidic chip for temperature control and freezing of biological solution. We opt for water as a nontoxic, effective refrigerant. Aqueous solutions are atomized in our device and evaporation of microdroplets under vacuum removes heat effectively. We achieve rapid cooling (−5.1 °C/s) and a low freezing temperature (−14.1 °C). Using this approach, we demonstrate freezing of deionized water and protein solution. Our simple, yet effective cooling device may improve many microfluidic applications currently relying on external power-hungry instruments for cooling and freezing.

Feed-forward control of a solid oxide fuel cell system with anode offgas recycle

NASA Astrophysics Data System (ADS)

Carré, Maxime; Brandenburger, Ralf; Friede, Wolfgang; Lapicque, François; Limbeck, Uwe; da Silva, Pedro

2015-05-01

In this work a combined heat and power unit (CHP unit) based on the solid oxide fuel cell (SOFC) technology is analysed. This unit has a special feature: the anode offgas is partially recycled to the anode inlet. Thus it is possible to increase the electrical efficiency and the system can be operated without external water feeding. A feed-forward control concept which allows secure operating conditions of the CHP unit as well as a maximization of its electrical efficiency is introduced and validated experimentally. The control algorithm requires a limited number of measurement values and few deterministic relations for its description.

The Design of the Trading Mechanism to Adapt the Development of Mixed Cooling Heating and Power

NASA Astrophysics Data System (ADS)

Liu, D. N.; Li, Z. H.; Zhou, H. M.; Zhao, Q.; Xu, X. F.

2017-08-01

The enterprise who has combined cooling heating and power system has both the customer group and the power generation resources. Therefore, it can be used as a power user, and can also be used as a power generation enterprise to participate in the direct purchase of electricity. This paper combines characteristics of mixed cooling heating and power, designs application business model of mixed cooling heating and power, and puts forward to the scene of cooling heating and power trading scheme, helping the enterprise according to the power supply and demand situation in the region adjust their positions and participate in the electricity market.

[Penetration of external thermal perturbations into homeothermic organisms, part I (author's transl)].

PubMed

Theves, B

1978-03-20

The general importance of the mean surface curvature for heat conduction problems is explained and a special symmetry with constant mean curvature on the isothermal surfaces is defined. The applicability for the body shapes of homeothermic organisms is demonstrated and the partial differential equation of heat conduction for this case is derived. The definition: heat release = real heat production + convective pseudoproduction eliminates the term of convective heat transfer through the blood stream and allows the reduction to a mere heat conduction problem. Formulas for the heat loss to the environment and for steady state temperature profiles are given. In case of sudden change of heat loss the partial differential equation is solved and a formula is derived, using dimensionless coordinates of time and distance. The mean surface curvature has strongest influence to the interior temperature field. The solution shows clearly the importance of thermal inertia of the homeothermic organism, for the external temperature wave penetrates into the body with a long phase displacement in time.

Power, muscular work, and external forces in cycling.

PubMed

de Groot, G; Welbergen, E; Clijsen, L; Clarijs, J; Cabri, J; Antonis, J

1994-01-01

Cycling performance is affected by the interaction of a number of variables, including environment, mechanical, and human factors. Engineers have focused on the development of more efficient bicycles. Kinesiologists have examined cycling performance from a human perspective. This paper summarizes only certain aspects of human ergonomics of cycling, especially those which are important for the recent current research in our departments. Power is a key to performance of physical work. During locomotion an imaginary flow of energy takes place from the metabolism to the environment, with some efficiency. The 'useful' mechanical muscle power output might be used to perform movements and to do work against the environment. The external power is defined as the sum of joint powers, each calculated as the product of the joint (net) moment and angular velocity. This definition of external power is closely related to the mean external power as applied to exercise physiology: the sum of joint powers reflects all mechanical power which in principle can be used to fulfil a certain task. In this paper, the flow of energy for cycling is traced quantitatively as far as possible. Studies on the total lower limb can give insight into the contribution of individual muscles to external power. The muscle velocity (positive or negative) is obtained from the positions and orientations of body segments and a bar linkage model of the lower limb. The muscle activity can be measured by electromyography. In this way, positive and negative work regions in individual muscles are identified. Synergy between active agonistic/antagonistic muscle groups occurs in order to deliver external power. Maximum power is influenced by body position, geometry of the bicycle and pedalling rate. This has to be interpreted in terms of the length-tension and force-velocity-power relationships of the involved muscles. Flat road and uphill cycling at different saddle-tube angles is simulated on an ergometer. The measured pedal forces (magnitude and direction) are only dependent on the intersegmental orientation of saddle tube, crank position, upper and lower leg, and foot. The changed direction of the gravitational force with respect to the saddle-tube does not interfere with the co-ordinated force production pattern. During locomotory cycling at constant speed the external power is mainly used to overcome the aerodynamic friction force. This force and the rolling resistance are determined by coasting down experiments, yielding the external power.(ABSTRACT TRUNCATED AT 400 WORDS)

Mortality during a Large-Scale Heat Wave by Place, Demographic Group, Internal and External Causes of Death, and Building Climate Zone.

PubMed

Joe, Lauren; Hoshiko, Sumi; Dobraca, Dina; Jackson, Rebecca; Smorodinsky, Svetlana; Smith, Daniel; Harnly, Martha

2016-03-09

Mortality increases during periods of elevated heat. Identification of vulnerable subgroups by demographics, causes of death, and geographic regions, including deaths occurring at home, is needed to inform public health prevention efforts. We calculated mortality relative risks (RRs) and excess deaths associated with a large-scale California heat wave in 2006, comparing deaths during the heat wave with reference days. For total (all-place) and at-home mortality, we examined risks by demographic factors, internal and external causes of death, and building climate zones. During the heat wave, 582 excess deaths occurred, a 5% increase over expected (RR = 1.05, 95% confidence interval (CI) 1.03-1.08). Sixty-six percent of excess deaths were at home (RR = 1.12, CI 1.07-1.16). Total mortality risk was higher among those aged 35-44 years than ≥ 65, and among Hispanics than whites. Deaths from external causes increased more sharply (RR = 1.18, CI 1.10-1.27) than from internal causes (RR = 1.04, CI 1.02-1.07). Geographically, risk varied by building climate zone; the highest risks of at-home death occurred in the northernmost coastal zone (RR = 1.58, CI 1.01-2.48) and the southernmost zone of California's Central Valley (RR = 1.43, CI 1.21-1.68). Heat wave mortality risk varied across subpopulations, and some patterns of vulnerability differed from those previously identified. Public health efforts should also address at-home mortality, non-elderly adults, external causes, and at-risk geographic regions.

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

Goodson, J.O.

This is the first of three volumes which document the historical development of the first US compressed-air energy storage (CAES) Power-generation facility. Volume 1 is a background report and presents a chronicle of the development of the CAES facility from the early interest in CAES until inception of engineering/construction on August 11, 1988. The 110 MW - 26 hr CAES plant is owned and operated by Alabama Electric Cooperative, Inc. (AEC) of Andalusia, Alabama. The plant is the first CAES plant in the United States and the world's first CAES facility incorporating a recuperator to improve efficiency. The plant suppliesmore » competitively priced peaking power to the AEC owner members. The economics of CAES-produced power is attractive because the energy-intensive air-compression mode is powered by relatively inexpensive base-load power external to the CAES plant. The compressed-air energy is stored underground until needed, and during the power-production mode, the only fuel required is that to heat the compressed air to expander-inlet temperature. The project development for AEC's CAES plant involved much planning and preliminary design work. Specifically, this included load and generation-planning studies, power-supply selections, conceptual designs, project administration, air-storage cavern and turbomachinery specifications and design, contract requirements, environmental and licensing issues, and construction planning.« less

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

Goodson, J.O.

This is the first of three volumes which document the historical development of the first US compressed-air energy storage (CAES) Power-generation facility. Volume 1 is a background report and presents a chronicle of the development of the CAES facility from the early interest in CAES until inception of engineering/construction on August 11, 1988. The 110 MW - 26 hr CAES plant is owned and operated by Alabama Electric Cooperative, Inc. (AEC) of Andalusia, Alabama. The plant is the first CAES plant in the United States and the world`s first CAES facility incorporating a recuperator to improve efficiency. The plant suppliesmore » competitively priced peaking power to the AEC owner members. The economics of CAES-produced power is attractive because the energy-intensive air-compression mode is powered by relatively inexpensive base-load power external to the CAES plant. The compressed-air energy is stored underground until needed, and during the power-production mode, the only fuel required is that to heat the compressed air to expander-inlet temperature. The project development for AEC`s CAES plant involved much planning and preliminary design work. Specifically, this included load and generation-planning studies, power-supply selections, conceptual designs, project administration, air-storage cavern and turbomachinery specifications and design, contract requirements, environmental and licensing issues, and construction planning.« less

Collective Evidence for Inverse Compton Emission from External Photons in High-Power Blazars

NASA Technical Reports Server (NTRS)

Meyer, Eileen T.; Fossati, Giovanni; Georganopoulos, Markos; Lister, Matthew L.

2012-01-01

We present the first collective evidence that Fermi-detected jets of high kinetic power (L(sub kin)) are dominated by inverse Compton emission from upscattered external photons. Using a sample with a broad range in orientation angle, including radio galaxies and blazars, we find that very high power sources (L(sub kin) > 10(exp 45.5) erg/s) show a significant increase in the ratio of inverse Compton to synchrotron power (Compton dominance) with decreasing orientation angle, as measured by the radio core dominance and confirmed by the distribution of superluminal speeds. This increase is consistent with beaming expectations for external Compton (EC) emission, but not for synchrotron self Compton (SSC) emission. For the lowest power jets (L(sub kin) < 10(exp 43.5) erg /s), no trend between Compton and radio core dominance is found, consistent with SSC. Importantly, the EC trend is not seen for moderately high power flat spectrum radio quasars with strong external photon fields. Coupled with the evidence that jet power is linked to the jet speed, this finding suggests that external photon fields become the dominant source of seed photons in the jet comoving frame only for the faster and therefore more powerful jets.

Multiple external hazards compound level 3 PSA methods research of nuclear power plant

NASA Astrophysics Data System (ADS)

Wang, Handing; Liang, Xiaoyu; Zhang, Xiaoming; Yang, Jianfeng; Liu, Weidong; Lei, Dina

2017-01-01

2011 Fukushima nuclear power plant severe accident was caused by both earthquake and tsunami, which results in large amount of radioactive nuclides release. That accident has caused the radioactive contamination on the surrounding environment. Although this accident probability is extremely small, once such an accident happens that is likely to release a lot of radioactive materials into the environment, and cause radiation contamination. Therefore, studying accidents consequences is important and essential to improve nuclear power plant design and management. Level 3 PSA methods of nuclear power plant can be used to analyze radiological consequences, and quantify risk to the public health effects around nuclear power plants. Based on multiple external hazards compound level 3 PSA methods studies of nuclear power plant, and the description of the multiple external hazards compound level 3 PSA technology roadmap and important technical elements, as well as taking a coastal nuclear power plant as the reference site, we analyzed the impact of off-site consequences of nuclear power plant severe accidents caused by multiple external hazards. At last we discussed the impact of off-site consequences probabilistic risk studies and its applications under multiple external hazards compound conditions, and explained feasibility and reasonableness of emergency plans implementation.

Miniature Heat Transport System for Nanosatellite Technology

NASA Technical Reports Server (NTRS)

Douglas, Donya M,

1999-01-01

The scientific understanding of key physical processes between the Sun and the Earth require simultaneous measurements from many vantage points in space. Nano-satellite technologies will enable a class of constellation missions for the NASA Space Science Sun-Earth Connections. This recent emphasis on the implementation of smaller satellites leads to a requirement for development of smaller subsystems in several areas. Key technologies under development include: advanced miniaturized chemical propulsion; miniaturized sensors; highly integrated, compact electronics; autonomous onboard and ground operations; miniatures low power tracking techniques for orbit determination; onboard RF communications capable of transmitting data to the ground from far distances; lightweight efficient solar array panels; lightweight, high output battery cells; lightweight yet strong composite materials for the nano-spacecraft and deployer-ship structures. These newer smaller systems may have higher power densities and higher thermal transport requirements than seen on previous small satellites. Furthermore, the small satellites may also have a requirement to maintain thermal control through extended earth shadows, possibly up to 8 hours long. Older thermal control technology, such as heaters, thermostats, and heat pipes, may not be sufficient to meet the requirements of these new systems. Conversely, a miniature two-phase heat transport system (Mini-HTS) such as a Capillary Pumped Loop (CPL) or Loop Heat Pipe (LBP) is a viable alternative. A Mini-HTS can provide fine temperature control, thermal diode action, and a highly efficient means of heat transfer. The Mini-HTS would have power capabilities in the range of tens of watts or less and provide thermal control over typical spacecraft ranges. The Mini-HTS would allow the internal portion of the spacecraft to be thermally isolated from the external radiator, thus protecting the internal components from extreme cold temperatures during an eclipse. The Mini-HTS would transport the beat from these components to a radiator during their operational modes, and it would be shutdown during non-operational or eclipse modes. Shutdown of the Mini-HTS would be accomplished with small heaters and has been successfully demonstrated on numerous occasions, both in the lab and on flight experiments. Efforts are now underway to miniaturize two-phase heat transport systems for the Nanosatellite project, with potential application to other small satellite programs. 'ne goal of this project is to design, build, and test miniature heat transport systems (MHTS) that would demonstrate the feasibility of a small Capillary Pumped Loop (CPL) or Loop Heat Pipe (LBP).

Energy dissipation of rigid dipoles in a viscous fluid under the action of a time-periodic field: The influence of thermal bath and dipole interaction

NASA Astrophysics Data System (ADS)

Lyutyy, T. V.; Reva, V. V.

2018-05-01

Ferrofluid heating by an external alternating field is studied based on the rigid dipole model, where the magnetization of each particle in a fluid is supposed to be firmly fixed in the crystal lattice. Equations of motion, employing Newton's second law for rotational motion, the condition of rigid body rotation, and the assumption that the friction torque is proportional to angular velocity are used. This oversimplification permits us to expand the model easily: to take into account the thermal noise and interparticle interaction that allows us to estimate from unified positions the role of thermal activation and dipole interaction in the heating process. Our studies are conducted in three stages. The exact expressions for the average power loss of a single particle are obtained within the dynamical approximation. Then, in the stochastic case, the power loss of a single particle is estimated analytically using the Fokker-Planck equation and numerically using the effective Langevin equation. Finally, the power loss for the particle ensemble is obtained using the molecular dynamics method. Here, the local dipole fields are calculated approximately based on the Barnes-Hut algorithm. The revealed trends in the behavior of both a single particle and the particle ensemble suggest the way of choosing the conditions for obtaining the maximum heating efficiency. The competitiveness character of the interparticle interaction and thermal noise is investigated in detail. Two situations, when the thermal noise rectifies the power loss reduction caused by the interaction, are described. The first of them is related to the complete destruction of dense clusters at high noise intensity. The second one originates from the rare switching of the particles in clusters due to thermal activation, when the noise intensity is relatively weak. In this way, the constructive role of noise appears in the system.

A study of the impact of moist-heat and dry-heat treatment processes on hazardous trace elements migration in food waste.

PubMed

Chen, Ting; Jin, Yiying; Qiu, Xiaopeng; Chen, Xin

2015-03-01

Using laboratory experiments, the authors investigated the impact of dry-heat and moist-heat treatment processes on hazardous trace elements (As, Hg, Cd, Cr, and Pb) in food waste and explored their distribution patterns for three waste components: oil, aqueous, and solid components. The results indicated that an insignificant reduction of hazardous trace elements in heat-treated waste-0.61-14.29% after moist-heat treatment and 4.53-12.25% after dry-heat treatment-and a significant reduction in hazardous trace elements (except for Hg without external addition) after centrifugal dehydration (P < 0.5). Moreover, after heat treatment, over 90% of the hazardous trace elements in the waste were detected in the aqueous and solid components, whereas only a trace amount of hazardous trace elements was detected in the oil component (<0.01%). In addition, results indicated that heat treatment process did not significantly reduce the concentration of hazardous trace elements in food waste, but the separation process for solid and aqueous components, such as centrifugal dehydration, could reduce the risk considerably. Finally, combined with the separation technology for solid and liquid components, dry-heat treatment is superior to moist-heat treatment on the removal of external water-soluble ionic hazardous trace elements. An insignificant reduction of hazardous trace elements in heat-treated waste showed that heat treatment does not reduce trace elements contamination in food waste considerably, whereas the separation process for solid and aqueous components, such as centrifugal dehydration, could reduce the risk significantly. Moreover, combined with the separation technology for solid and liquid components, dry-heat treatment is superior to moist-heat treatment for the removal of external water-soluble ionic hazardous trace elements, by exploring distribution patterns of trace elements in three waste components: oil, aqueous, and solid components.

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...

Heat transfer tests of an 0.006-scale thin-skin space shuttle thermocouple model (141-OT) in the Langley Research Center Freon tunnel at M-6 (IH18). [wind tunnel tests

NASA Technical Reports Server (NTRS)

Walstad, D. G.

1976-01-01

Ascent heating data were obtained at conditions simulating real gas effects at hypersonic Mach numbers. The configurations tested were Orbiter alone, external tank alone, and mated Orbiter and external tank. A boundary layer trip investigation was conducted for all configurations. The test was conducted at Mach 6 and Reynolds number of one half million per foot for 0 deg and -5 deg angle-of-attack. Selected thermocouples were chosen from the Orbiter and external tank to be used for obtaining heat transfer measurements. A maximum of 42 thermocouples could be measured by the facility data acquisition at one time and no attempt was made to record the excess thermocouples located on the model. Photographs of the test configurations are shown.

Experimental performance of an ablative material as an external insulator for a hypersonic research aircraft

NASA Technical Reports Server (NTRS)

Puster, R. L.; Chapman, A. J.

1977-01-01

An ablative material composed of silica-filled elastomeric silicone was tested to evaluate its thermal and structural performance as an external insulator, or heat shield, for a hypersonic research aircraft. The material was also tested to determine whether it would form a durable char layer when initially heated and thereafter function primarily as an insulator with little further pyrolysis or char removal. Aerothermal tests were representative of nominal Mach 6 cruise conditions of the aircraft, and additional tests were representative of Mach 8 cruise and interference heating conditions. Radiant heating tests were used to simulate the complete nominal Mach 6 surface-temperature history. The silica char that formed during aerothermal tests was not durable. The char experienced a general and preferential surface recession, with the primary mechanism for char removal being erosion. Tests revealed that radiant heating is not a valid technique for simulating aerodynamic heating of the material.

KSC-2011-6664

NASA Image and Video Library

2011-06-30

CAPE CANAVERAL, Fla. -- In the high bay of the RTG storage facility at NASA's Kennedy Space Center in Florida, a Department of Energy contractor employee guides the external and internal protective layers of the shipping cask as they are lifted from around the multi-mission radioisotope thermoelectric generator (MMRTG) for NASA's Mars Science Laboratory mission. The MMRTG no longer needs supplemental cooling since any excess heat generated can dissipate into the air in the high bay. The MMRTG will generate the power needed for the mission from the natural decay of plutonium-238, a non-weapons-grade form of the radioisotope. Heat given off by this natural decay will provide constant power through the day and night during all seasons. Waste heat from the MMRTG will be circulated throughout the rover system to keep instruments, computers, mechanical devices and communications systems within their operating temperature ranges. MSL's components include a compact car-sized rover, Curiosity, which has 10 science instruments designed to search for evidence on whether Mars has had environments favorable to microbial life, including chemical ingredients for life. The unique rover will use a laser to look inside rocks and release its gasses so that the rover’s spectrometer can analyze and send the data back to Earth. Launch of MSL aboard a United Launch Alliance Atlas V rocket is scheduled for Nov. 25 from Space Launch Complex 41 on Cape Canaveral Air Force Station in Florida. For more information, visit http://www.nasa.gov/msl. Photo credit: NASA/Frankie Martin

A unified model of density limit in fusion plasmas

NASA Astrophysics Data System (ADS)

Zanca, P.; Sattin, F.; Escande, D. F.; Pucella, G.; Tudisco, O.

2017-05-01

In this work we identify by analytical and numerical means the conditions for the existence of a magnetic and thermal equilibrium of a cylindrical plasma, in the presence of Ohmic and/or additional power sources, heat conduction and radiation losses by light impurities. The boundary defining the solutions’ space having realistic temperature profile with small edge value takes mathematically the form of a density limit (DL). Compared to previous similar analyses the present work benefits from dealing with a more accurate set of equations. This refinement is elementary, but decisive, since it discloses a tenuous dependence of the DL on the thermal transport for configurations with an applied electric field. Thanks to this property, the DL scaling law is recovered almost identical for two largely different devices such as the ohmic tokamak and the reversed field pinch. In particular, they have in common a Greenwald scaling, linearly depending on the plasma current, quantitatively consistent with experimental results. In the tokamak case the DL dependence on any additional heating approximately follows a 0.5 power law, which is compatible with L-mode experiments. For a purely externally heated configuration, taken as a cylindrical approximation of the stellarator, the DL dependence on transport is found stronger. By adopting suitable transport models, DL takes on a Sudo-like form, in fair agreement with LHD experiments. Overall, the model provides a good zeroth-order quantitative description of the DL, applicable to widely different configurations.

Desktop Systems for Manufacturing Carbon Nanotube Films by Chemical Vapor Deposition

DTIC Science & Technology

2007-06-01

existing low cost tube furnace designs limit the researcher’s ability to fully separate critical reaction parameters such as temperature and flow...Often heated using an external resistive heater coil, a typical configuration, shown in Figure 4, might place a tube made of a non- reactive ...researcher’s ability to fully separate critical parameters such as temperature and flow profiles. Additionally, the use of heating elements external to

Survey of manufacturers of high-performance heat engines adaptable to solar applications

NASA Technical Reports Server (NTRS)

Stine, W. B.

1984-01-01

The results of an industry survey made during the summer of 1983 are summarized. The survey was initiated in order to develop an information base on advanced engines that could be used in the solar thermal dish-electric program. Questionnaires inviting responses were sent to 39 companies known to manufacture or integrate externally heated engines. Follow-up telephone communication ensured uniformity of response. It appears from the survey that the technology exists to produce external-heat-addition engines of appropriate size with thermal efficiencies of over 40%. Problem areas are materials and sealing.

Phenomenology of break-up modes in contact free externally heated nanoparticle laden fuel droplets

NASA Astrophysics Data System (ADS)

Pathak, Binita; Basu, Saptarshi

2016-12-01

We study thermally induced atomization modes in contact free (acoustically levitated) nanoparticle laden fuel droplets. The initial droplet size, external heat supplied, and suspended particle concentration (wt. %) in droplets govern the stability criterion which ultimately determines the dominant mode of atomization. Pure fuel droplets exhibit two dominant modes of breakup namely primary and secondary. Primary modes are rather sporadic and normally do not involve shape oscillations. Secondary atomization however leads to severe shape deformations and catastrophic intense breakup of the droplets. The dominance of these modes has been quantified based on the external heat flux, dynamic variation of surface tension, acoustic pressure, and droplet size. Addition of particles alters the regimes of the primary and secondary atomization and introduces bubble induced boiling and bursting. We analyze this new mode of atomization and estimate the time scale of bubble growth up to the point of bursting using energy balance to determine the criterion suitable for parent droplet rupture. All the three different modes of breakup have been well identified in a regime map determined in terms of Weber number and the heat utilization rate which is defined as the energy utilized for transient heating, vaporization, and boiling in droplets.

Methods for determining optical power, for power-normalizing laser measurements, and for stabilizing power of lasers via compliance voltage sensing

DOEpatents

Taubman, Matthew S; Phillips, Mark C

2015-04-07

A method is disclosed for power normalization of spectroscopic signatures obtained from laser based chemical sensors that employs the compliance voltage across a quantum cascade laser device within an external cavity laser. The method obviates the need for a dedicated optical detector used specifically for power normalization purposes. A method is also disclosed that employs the compliance voltage developed across the laser device within an external cavity semiconductor laser to power-stabilize the laser mode of the semiconductor laser by adjusting drive current to the laser such that the output optical power from the external cavity semiconductor laser remains constant.

Heat transfer experiments with a central receiver tube subjected to unsteady and non-uniform heat flux

NASA Astrophysics Data System (ADS)

Fernández-Torrijos, María; Marugán-Cruz, Carolina; Sobrino, Celia; Santana, Domingo

2017-06-01

In this work, a molten salt test loop to study the heat transfer process in external molten salt receivers is described. The experimental installation is formed by a cylindrical molten salt tank, a pump, a flow meter, and an induction heater to generate the heat flux, which is applied in a small rectangular region of the tube surface. In central tower plants, the external receiver pipe is considered to be under unilateral concentrated solar radiation, because only one side of the pipe receives high heat flux. The main advantage of using an induction heater is the control of heating in different areas of the tube. In order to measure the effects of a non-homogenous and unsteady heat flux on the wall temperature distribution a series of experiments have been carried out. 4 K-type thermocouples have been welded at different axial and azimuthal positions of the pipe to obtain the wall temperature distribution. Different temperature measurements have been made varying the heat flux and water velocity to study their effects on the heat transfer process.

Matrix-assisted energy conversion in nanostructured piezoelectric arrays

DOEpatents

Sirbuly, Donald J.; Wang, Xianying; Wang, Yinmin

2013-01-01

A nanoconverter is capable of directly generating electricity through a nanostructure embedded in a polymer layer experiencing differential thermal expansion in a stress transfer zone. High surface-to-volume ratio semiconductor nanowires or nanotubes (such as ZnO, silicon, carbon, etc.) are grown either aligned or substantially vertically aligned on a substrate. The resulting nanoforest is then embedded with the polymer layer, which transfers stress to the nanostructures in the stress transfer zone, thereby creating a nanostructure voltage output due to the piezoelectric effect acting on the nanostructure. Electrodes attached at both ends of the nanostructures generate output power at densities of .about.20 nW/cm.sup.2 with heating temperatures of .about.65.degree. C. Nanoconverters arrayed in a series parallel arrangement may be constructed in planar, stacked, or rolled arrays to supply power to nano- and micro-devices without use of external batteries.

Electromagnetic braking for Mars spacecraft

NASA Technical Reports Server (NTRS)

Holt, A. C.

1986-01-01

Aerobraking concepts are being studied to improve performance and cost effectiveness of propulsion systems for Mars landers and Mars interplanetary spacecraft. Access to megawatt power levels (nuclear power coupled to high-storage inductive or capacitive devices) on a manned Mars interplanetary spacecraft may make feasible electromagnetic braking and lift modulation techniques which were previously impractical. Using pulsed microwave and magnetic field technology, potential plasmadynamic braking and hydromagnetic lift modulation techniques have been identified. Entry corridor modulation to reduce loads and heating, to reduce vertical descent rates, and to expand horizontal and lateral landing ranges are possible benefits. In-depth studies are needed to identify specific design concepts for feasibility assessments. Standing wave/plasma sheath interaction techniques appear to be promising. The techniques may require some tailoring of spacecraft external structures and materials. In addition, rapid response guidance and control systems may require the use of structurally embedded sensors coupled to expert systems or to artificial intelligence systems.

Preliminary design of an auxiliary power unit for the space shuttle. Volume 5: Selected system cycle performance data

NASA Technical Reports Server (NTRS)

Hamilton, M. L.; Burriss, W. L.

1972-01-01

Detailed cycle steady-state performance data are presented for the final auxiliary power unit (APU) system configuration. The selection configuration is a hydrogen-oxygen APU incorporating a recuperator to utilize the exhaust energy and using the cycle hydrogen flow as a means of cooling the component heat loads. The data are given in the form of computer printouts and provide the following: (1) verification of the adequacy of the design to meet the problem statement for steady-state performance; (2) overall system performance data for the vehicle system analyst to determine propellant consumption and hydraulic fluid temperature as a function for varying mission profiles, propellant inlet conditions, etc.; and (3) detailed component performance and cycle state point data to show what is happening in the cycle as a function of the external forcing functions.

Thermal energy storage for the Stirling engine powered automobile

NASA Technical Reports Server (NTRS)

Morgan, D. T. (Editor)

1979-01-01

A thermal energy storage (TES) system developed for use with the Stirling engine as an automotive power system has gravimetric and volumetric storage densities which are competitive with electric battery storage systems, meets all operational requirements for a practical vehicle, and can be packaged in compact sized automobiles with minimum impact on passenger and freight volume. The TES/Stirling system is the only storage approach for direct use of combustion heat from fuel sources not suitable for direct transport and use on the vehicle. The particular concept described is also useful for a dual mode TES/liquid fuel system in which the TES (recharged from an external energy source) is used for short duration trips (approximately 10 miles or less) and liquid fuel carried on board the vehicle used for long duration trips. The dual mode approach offers the potential of 50 percent savings in the consumption of premium liquid fuels for automotive propulsion in the United States.

Commissioning and Performance Analysis of WhisperGen Stirling Engine

NASA Astrophysics Data System (ADS)

Pradip, Prashant Kaliram

Stirling engine based cogeneration systems have potential to reduce energy consumption and greenhouse gas emission, due to their high cogeneration efficiency and emission control due to steady external combustion. To date, most studies on this unit have focused on performance based on both experimentation and computer models, and lack experimental data for diversified operating ranges. This thesis starts with the commissioning of a WhisperGen Stirling engine with components and instrumentation to evaluate power and thermal performance of the system. Next, a parametric study on primary engine variables, including air, diesel, and coolant flowrate and temperature were carried out to further understand their effect on engine power and efficiency. Then, this trend was validated with the thermodynamic model developed for the energy analysis of a Stirling cycle. Finally, the energy balance of the Stirling engine was compared without and with heat recovery from the engine block and the combustion chamber exhaust.

A graphic approach to include dissipative-like effects in reversible thermal cycles

NASA Astrophysics Data System (ADS)

Gonzalez-Ayala, Julian; Arias-Hernandez, Luis Antonio; Angulo-Brown, Fernando

2017-05-01

Since the decade of 1980's, a connection between a family of maximum-work reversible thermal cycles and maximum-power finite-time endoreversible cycles has been established. The endoreversible cycles produce entropy at their couplings with the external heat baths. Thus, this kind of cycles can be optimized under criteria of merit that involve entropy production terms. Meanwhile the relation between the concept of work and power is quite direct, apparently, the finite-time objective functions involving entropy production have not reversible counterparts. In the present paper we show that it is also possible to establish a connection between irreversible cycle models and reversible ones by means of the concept of "geometric dissipation", which has to do with the equivalent role of a deficit of areas between some reversible cycles and the Carnot cycle and actual dissipative terms in a Curzon-Ahlborn engine.

Stirling Engine External Heat System Design with Heat Pipe Heater.

DTIC Science & Technology

1986-07-01

Figure 10. However, the evaporator analysis is greatly simplified by making the conservative assumption of constant heat flux. This assumption results in...number Cold Start Data * " ROM density of the metal, gr/cm 3 CAPM specific heat of the metal, cal./gr. K ETHG effective gauze thickness: the

Combined heat and power supply using Carnot engines

NASA Astrophysics Data System (ADS)

Horlock, J. H.

The Marshall Report on the thermodynamic and economic feasibility of introducing large scale combined heat and electrical power generation (CHP) into the United Kingdom is summarized. Combinations of reversible power plant (Carnot engines) to meet a given demand of power and heat production are analyzed. The Marshall Report states that fairly large scale CHP plants are an attractive energy saving option for areas of high heat load densities. Analysis shows that for given requirements, the total heat supply and utilization factor are functions of heat output, reservoir supply temperature, temperature of heat rejected to the reservoir, and an intermediate temperature for district heating.

Recent Advances in Active Infrared Thermography for Non-Destructive Testing of Aerospace Components.

PubMed

Ciampa, Francesco; Mahmoodi, Pooya; Pinto, Fulvio; Meo, Michele

2018-02-16

Active infrared thermography is a fast and accurate non-destructive evaluation technique that is of particular relevance to the aerospace industry for the inspection of aircraft and helicopters' primary and secondary structures, aero-engine parts, spacecraft components and its subsystems. This review provides an exhaustive summary of most recent active thermographic methods used for aerospace applications according to their physical principle and thermal excitation sources. Besides traditional optically stimulated thermography, which uses external optical radiation such as flashes, heaters and laser systems, novel hybrid thermographic techniques are also investigated. These include ultrasonic stimulated thermography, which uses ultrasonic waves and the local damage resonance effect to enhance the reliability and sensitivity to micro-cracks, eddy current stimulated thermography, which uses cost-effective eddy current excitation to generate induction heating, and microwave thermography, which uses electromagnetic radiation at the microwave frequency bands to provide rapid detection of cracks and delamination. All these techniques are here analysed and numerous examples are provided for different damage scenarios and aerospace components in order to identify the strength and limitations of each thermographic technique. Moreover, alternative strategies to current external thermal excitation sources, here named as material-based thermography methods, are examined in this paper. These novel thermographic techniques rely on thermoresistive internal heating and offer a fast, low power, accurate and reliable assessment of damage in aerospace composites.

CHF Enhancement by Vessel Coating for External Reactor Vessel Cooling

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

Fan-Bill Cheung; Joy L. Rempe

2004-06-01

In-vessel retention (IVR) is a key severe accident management (SAM) strategy that has been adopted by some operating nuclear power plants and advanced light water reactors (ALWRs). One viable means for IVR is the method of external reactor vessel cooling (ERVC) by flooding of the reactor cavity during a severe accident. As part of a joint Korean – United States International Nuclear Energy Research Initiative (K-INERI), an experimental study has been conducted to investigate the viability of using an appropriate vessel coating to enhance the critical heat flux (CHF) limits during ERVC. Toward this end, transient quenching and steady-state boilingmore » experiments were performed in the SBLB (Subscale Boundary Layer Boiling) facility at Penn State using test vessels with micro-porous aluminum coatings. Local boiling curves and CHF limits were obtained in these experiments. When compared to the corresponding data without coatings, substantial enhancement in the local CHF limits for the case with surface coatings was observed. Results of the steady state boiling experiments showed that micro-porous aluminum coatings were very durable. Even after many cycles of steady state boiling, the vessel coatings remained rather intact, with no apparent changes in color or structure. Moreover, the heat transfer performance of the coatings was found to be highly desirable with an appreciable CHF enhancement in all locations on the vessel outer surface but with very little effect of aging.« less

Recent Advances in Active Infrared Thermography for Non-Destructive Testing of Aerospace Components

PubMed Central

Mahmoodi, Pooya; Pinto, Fulvio; Meo, Michele

2018-01-01

Active infrared thermography is a fast and accurate non-destructive evaluation technique that is of particular relevance to the aerospace industry for the inspection of aircraft and helicopters’ primary and secondary structures, aero-engine parts, spacecraft components and its subsystems. This review provides an exhaustive summary of most recent active thermographic methods used for aerospace applications according to their physical principle and thermal excitation sources. Besides traditional optically stimulated thermography, which uses external optical radiation such as flashes, heaters and laser systems, novel hybrid thermographic techniques are also investigated. These include ultrasonic stimulated thermography, which uses ultrasonic waves and the local damage resonance effect to enhance the reliability and sensitivity to micro-cracks, eddy current stimulated thermography, which uses cost-effective eddy current excitation to generate induction heating, and microwave thermography, which uses electromagnetic radiation at the microwave frequency bands to provide rapid detection of cracks and delamination. All these techniques are here analysed and numerous examples are provided for different damage scenarios and aerospace components in order to identify the strength and limitations of each thermographic technique. Moreover, alternative strategies to current external thermal excitation sources, here named as material-based thermography methods, are examined in this paper. These novel thermographic techniques rely on thermoresistive internal heating and offer a fast, low power, accurate and reliable assessment of damage in aerospace composites. PMID:29462953

Use of near-IR to monitor the influence of external heating on dental composite photopolymerization.

PubMed

Trujillo, Marianela; Newman, Sheldon M; Stansbury, Jeffrey W

2004-10-01

This study was conducted to determine the effect of modest external heating on the photopolymerization kinetics and conversion of commercial dental composite restorative materials. A transmission-mode, real-time near-infrared spectroscopic technique was used to monitor the photopolymerization process in the composite materials at various temperatures between 23 and 70 degrees C. Several light curing units, differing in spectral output and power densities were compared at the different cure temperatures. Several significantly different commercial composites were compared for their response. Regardless of the curing light or composite material used, photopolymerization at a moderate curing temperature of 54.5 degrees C resulted in significantly higher immediate and final conversion values compared with room temperature photocuring. Contrary to the room temperature cured materials, at the elevated cure temperature the extent of post-cure was minor and different curing lights produced very uniform conversion values within a given material. The time required to reach a given level of conversion, established as full conversion with the room temperature cure, was reduced typically by 80-90% using the elevated curing conditions. Complementary kinetic studies confirmed the effect of cure temperature on increasing the polymerization rate in dental composites as significant. Increasing the temperature of composite resin within potentially biologically compatible limits can significantly influences resin polymerization. These increased rates and conversion could lead to improved properties of composite restorative materials.

Synchronization of distributed power grids with the external loading system

NASA Astrophysics Data System (ADS)

Wei, Duqu; Mei, Chuncao

2018-06-01

In this paper, the synchronization between spatially distributed power plants and their supported consumers is studied, where the case of Kuramoto-like model power grids connected to an external permanent magnet synchronous motor (PMSM) is taken as an example. We focus on the dependence of the synchronization on the coupling coefficient. To quantitatively study the synchronization degree, we introduce the order parameter and the frequency deviation to measure the synchronization of the coupled system. It is found that as the external coupling coefficient is increased, the distributed power grids and the loading system become more and more synchronized in space, and the complete synchronization appears at a particular value of external coupling coefficient. Our results may provide a useful tip for analyzing the synchronous ability of distributed power grids.

Experimental study of heating scheme effect on the inner divertor power footprint widths in EAST lower single null discharges

NASA Astrophysics Data System (ADS)

Deng, G. Z.; Xu, J. C.; Liu, X.; Liu, X. J.; Liu, J. B.; Zhang, H.; Liu, S. C.; Chen, L.; Yan, N.; Feng, W.; Liu, H.; Xia, T. Y.; Zhang, B.; Shao, L. M.; Ming, T. F.; Xu, G. S.; Guo, H. Y.; Xu, X. Q.; Gao, X.; Wang, L.

2018-04-01

A comprehensive work of the effects of plasma current and heating schemes on divertor power footprint widths is carried out in the experimental advanced superconducting tokamak (EAST). The divertor power footprint widths, i.e., the scrape-off layer heat flux decay length λ q and the heat spreading S, are crucial physical and engineering parameters for fusion reactors. Strong inverse scaling of λ q and S with plasma current have been demonstrated for both neutral beam (NB) and lower hybrid wave (LHW) heated L-mode and H-mode plasmas at the inner divertor target. For plasmas heated by the combination of the two kinds of auxiliary heating schemes (NB and LHW), the divertor power widths tend to be larger in plasmas with higher ratio of LHW power. Comparison between experimental heat flux profiles at outer mid-plane (OMP) and divertor target for NB heated and LHW heated L-mode plasmas reveals that the magnetic topology changes induced by LHW may be the main reason to the wider divertor power widths in LHW heated discharges. The effect of heating schemes on divertor peak heat flux has also been investigated, and it is found that LHW heated discharges tend to have a lower divertor peak heat flux compared with NB heated discharges under similar input power. All these findings seem to suggest that plasmas with LHW auxiliary heating scheme are better heat exhaust scenarios for fusion reactors and should be the priorities for the design of next-step fusion reactors like China Fusion Engineering Test Reactor.

Experimental and numerical investigation of one and two phase natural convection in storage tanks

NASA Astrophysics Data System (ADS)

Aszodi, A.; Krepper, E.; Prasser, H.-M.

Experiments were performed to investigate heating up processes of fluids in storage tanks under the influence of an external heat source. As a consequence of an external fire, the heat-up of the inventory may lead to the evaporation of the liquid and to release of significant quantities of dangerous gases into the environment. Several tests were performed both with heating from the bottom and with heating from the side walls. In recent tests in addition to thermocouples, the tank was equipped with needle probes for measuring of the local void fraction. The paper presents experimental and numerical investigations of single and two phase heating up processes of tanks with side wall heating. The measurement of the temperature and of the void fraction makes interesting phenomena evident, which could be explained by an own 2D model. The gained experimental results may be used for the validation of boiling models in 3D CFD codes.

Spacecraft Thermal Control

NASA Technical Reports Server (NTRS)

Birur, Gajanana C.; Siebes, Georg; Swanson, Theodore D.; Powers, Edward I. (Technical Monitor)

2001-01-01

Thermal control of the spacecraft is typically achieved by removing heat from the spacecraft parts that tend to overheat and adding heat to the parts that tend get too cold. The equipment on the spacecraft can get very hot if it is exposed to the sun or have internal heat generation. The pans also can get very cold if they are exposed to the cold of deep space. The spacecraft and instruments must be designed to achieve proper thermal balance. The combination of the spacecraft's external thermal environment, its internal heat generation (i.e., waste heat from the operation of electrical equipment), and radiative heat rejection will determine this thermal balance. It should also be noted that this is seldom a static situation, external environmental influences and internal heat generation are normally dynamic variables which change with time. Topics discussed include thermal control system components, spacecraft mission categories, spacecraft thermal requirements, space thermal environments, thermal control hardware, launch and flight operations, advanced technologies for future spacecraft,

Variable pressure power cycle and control system

DOEpatents

Goldsberry, Fred L.

1984-11-27

A variable pressure power cycle and control system that is adjustable to a variable heat source is disclosed. The power cycle adjusts itself to the heat source so that a minimal temperature difference is maintained between the heat source fluid and the power cycle working fluid, thereby substantially matching the thermodynamic envelope of the power cycle to the thermodynamic envelope of the heat source. Adjustments are made by sensing the inlet temperature of the heat source fluid and then setting a superheated vapor temperature and pressure to achieve a minimum temperature difference between the heat source fluid and the working fluid.

Multiresponsive Kinematics and Robotics of Surface-Patterned Polymer Film.

PubMed

Liang, Shumin; Qiu, Xiaxin; Yuan, Jun; Huang, Wei; Du, Xuemin; Zhang, Lidong

2018-06-06

Soft robots, sensors, and energy harvesters require materials that are capable of converting external stimuli to visible deformations, especially when shape-programmable deformations are desired. Herein, we develop a polymer film that can reversibly respond to humidity, heating, and acetone vapors with the generation of shape-programmable large deformations. Poly(vinylidene fluoride) film, capable of providing acetone responsiveness, is designed with microchannel patterns created on its one side by using templates, and the microchannels-patterned side is then treated with hygroscopic 3-aminopropyltriethoxysilane (APTES) to give humidity/heating-responsive elements. The APTES-modified microchannels lead to anisotropic flexural modulus and hygroscopicity in the film, resulting in the shape-programmed kinematics depending on the orientations of surface microchannels. As the microchannels align at oblique/right angles with respect to the long axis of the film strips, the coiling/curling motions can be generated in response to the stimuli, and the better motion performances are found in humidity- and heating-driven systems. This material utilized in self-adaptive soft robots exhibits prominent toughness, powerful strength, and long endurance for converting humidity and heat to mechanical works including transportation of lightweight objects, automatic sensing cap, and mimicking crawling in nature. We thus believe that this material with shape-programmable multisensing capability might be suitable for soft machines and robotics.

A finite element analysis of the freeze/thaw behavior of external artery heat pipes

NASA Technical Reports Server (NTRS)

Lu, X. J.; Peterson, G. P.

1993-01-01

A two-dimensional finite element model was used to determine the freeze/thaw characteristics of an external artery heat pipe. During startup, the working fluid, which was located in the liquid channel and the circumferential wall grooves, experienced a phase transformation from a solid to a liquid state. The transient heat conduction equations with moving interfacial conditions were solved using the appropriate initial boundary conditions. The modelling results include the cross-sectional temperature distribution and the interfacial or melt front position as a function of time. A fixed grid approach was adopted in the model for the phase-change process during thawing of frozen working fluid. The interfacial position between the liquid and solid regions was found by balancing the latent heat caused by interfacial movement with the heat addition or extraction at the related grid points.

Integration and software for thermal test of heat rate sensors. [space shuttle external tank

NASA Technical Reports Server (NTRS)

Wojciechowski, C. J.; Shrider, K. R.

1982-01-01

A minicomputer controlled radiant test facility is described which was developed and calibrated in an effort to verify analytical thermal models of instrumentation islands installed aboard the space shuttle external tank to measure thermal flight parameters during ascent. Software was provided for the facility as well as for development tests on the SRB actuator tail stock. Additional testing was conducted with the test facility to determine the temperature and heat flux rate and loads required to effect a change of color in the ET tank external paint. This requirement resulted from the review of photographs taken of the ET at separation from the orbiter which showed that 75% of the external tank paint coating had not changed color from its original white color. The paint on the remaining 25% of the tank was either brown or black, indicating that it had degraded due to heating or that the spray on form insulation had receded in these areas. The operational capability of the facility as well as the various tests which were conducted and their results are discussed.

System Statement of Tasks of Calculating and Providing the Reliability of Heating Cogeneration Plants in Power Systems

NASA Astrophysics Data System (ADS)

Biryuk, V. V.; Tsapkova, A. B.; Larin, E. A.; Livshiz, M. Y.; Sheludko, L. P.

2018-01-01

A set of mathematical models for calculating the reliability indexes of structurally complex multifunctional combined installations in heat and power supply systems was developed. Reliability of energy supply is considered as required condition for the creation and operation of heat and power supply systems. The optimal value of the power supply system coefficient F is based on an economic assessment of the consumers’ loss caused by the under-supply of electric power and additional system expences for the creation and operation of an emergency capacity reserve. Rationing of RI of the industrial heat supply is based on the use of concept of technological margin of safety of technological processes. The definition of rationed RI values of heat supply of communal consumers is based on the air temperature level iside the heated premises. The complex allows solving a number of practical tasks for providing reliability of heat supply for consumers. A probabilistic model is developed for calculating the reliability indexes of combined multipurpose heat and power plants in heat-and-power supply systems. The complex of models and calculation programs can be used to solve a wide range of specific tasks of optimization of schemes and parameters of combined heat and power plants and systems, as well as determining the efficiency of various redundance methods to ensure specified reliability of power supply.

Mortality during a Large-Scale Heat Wave by Place, Demographic Group, Internal and External Causes of Death, and Building Climate Zone

PubMed Central

Joe, Lauren; Hoshiko, Sumi; Dobraca, Dina; Jackson, Rebecca; Smorodinsky, Svetlana; Smith, Daniel; Harnly, Martha

2016-01-01

Mortality increases during periods of elevated heat. Identification of vulnerable subgroups by demographics, causes of death, and geographic regions, including deaths occurring at home, is needed to inform public health prevention efforts. We calculated mortality relative risks (RRs) and excess deaths associated with a large-scale California heat wave in 2006, comparing deaths during the heat wave with reference days. For total (all-place) and at-home mortality, we examined risks by demographic factors, internal and external causes of death, and building climate zones. During the heat wave, 582 excess deaths occurred, a 5% increase over expected (RR = 1.05, 95% confidence interval (CI) 1.03–1.08). Sixty-six percent of excess deaths were at home (RR = 1.12, CI 1.07–1.16). Total mortality risk was higher among those aged 35–44 years than ≥65, and among Hispanics than whites. Deaths from external causes increased more sharply (RR = 1.18, CI 1.10–1.27) than from internal causes (RR = 1.04, CI 1.02–1.07). Geographically, risk varied by building climate zone; the highest risks of at-home death occurred in the northernmost coastal zone (RR = 1.58, CI 1.01–2.48) and the southernmost zone of California’s Central Valley (RR = 1.43, CI 1.21–1.68). Heat wave mortality risk varied across subpopulations, and some patterns of vulnerability differed from those previously identified. Public health efforts should also address at-home mortality, non-elderly adults, external causes, and at-risk geographic regions. PMID:27005646

Heat Rejection Concepts for Brayton Power Conversion Systems

NASA Technical Reports Server (NTRS)

Siamidis, John; Mason, Lee; Beach, Duane; Yuko, James

2005-01-01

This paper describes potential heat rejection design concepts for closed Brayton cycle (CBC) power conversion systems. Brayton conversion systems are currently under study by NASA for Nuclear Electric Propulsion (NEP) applications. The Heat Rejection Subsystem (HRS) must dissipate waste heat generated by the power conversion system due to inefficiencies in the thermal-to-electric conversion process. Space Brayton conversion system designs tend to optimize at efficiencies of about 20 to 25 percent with radiator temperatures in the 400 to 600 K range. A notional HRS was developed for a 100 kWe-class Brayton power system that uses a pumped sodium-potassium (NaK) heat transport loop coupled to a water heat pipe radiator. The radiator panels employ a sandwich construction consisting of regularly-spaced circular heat pipes contained within two composite facesheets. Heat transfer from the NaK fluid to the heat pipes is accomplished by inserting the evaporator sections into the NaK duct channel. The paper evaluates various design parameters including heat pipe diameter, heat pipe spacing, and facesheet thickness. Parameters were varied to compare design options on the basis of NaK pump pressure rise and required power, heat pipe unit power and radial flux, radiator panel areal mass, and overall HRS mass.

LD side-pumped Nd:YAG Q-switched laser without water cooling

NASA Astrophysics Data System (ADS)

Ling, Ming; Jin, Guang-yong; Tan, Xue-chun; Wu, Zhi-chao; Liang, Zhu

2009-07-01

A novel LD side-pumped Nd:YAG Q-switched solid-state laser, which made use of the special pumping strcture with conductive cooling instead of water cooling, was investigated.After selecting an appropriate length and diameter of Nd:YAG laser crystal rod and using three groups of laser diode centimeter bar which was composed by 12 laser diodes and uniformly arranged according to the angle of 120°,side-pumping structure of laser was accomplished.Adopting plano-concave resonator ,mending double end face of laser crystal and designing heat-stability resonator made the resonator steadily oscillate.Laser crystal rod which was tight fastened by copper net was conductively cooled and radiation block was furnished on the external of copper net for increasing the radiation capacity.High reflection gold film was plated on the cooling wall in the opposite way of pumping light, so that the laser crystal was uniformly pumped and the laser with low order mode output.Making the use of pillar lens focus and ray trace computing, reasonable parameters were caculated to couple pumping light to laser with high-efficiency.It was the electrooptic Q-switched which was made to be micro-integration eliminating voltage by KD*P crystal that improved the ratio between acting and unacting.Inner heat radiated from laser in good time with TE cooler and the laser ran at constant temperature with water cooling when the big external heat sink emanated a steady heat to periphery. Experiments revealed that the syetem pumping efficiency riseed by 18% and the laser threshold energy was 192 mJ under the condition of this novel pumping structure. The low mode output of 10-12ns pulse width and the maximum output energy of 98 mJ was achieved with an incident pump energy of 720 mJ in 1064nm.The optical-to-optical conversion efficiency was up to 13. 6 %,and the power instability in 24 h was better than +/-1. 7 %.

A heat receiver design for solar dynamic space power systems

NASA Technical Reports Server (NTRS)

Baker, Karl W.; Dustin, Miles O.; Crane, Roger

1990-01-01

An advanced heat pipe receiver designed for a solar dynamic space power system is described. The power system consists of a solar concentrator, solar heat receiver, Stirling heat engine, linear alternator and waste heat radiator. The solar concentrator focuses the sun's energy into a heat receiver. The engine and alternator convert a portion of this energy to electric power and the remaining heat is rejected by a waste heat radiator. Primary liquid metal heat pipes transport heat energy to the Stirling engine. Thermal energy storage allows this power system to operate during the shade portion of an orbit. Lithium fluoride/calcium fluoride eutectic is the thermal energy storage material. Thermal energy storage canisters are attached to the midsection of each heat pipe. The primary heat pipes pass through a secondary vapor cavity heat pipe near the engine and receiver interface. The secondary vapor cavity heat pipe serves three important functions. First, it smooths out hot spots in the solar cavity and provides even distribution of heat to the engine. Second, the event of a heat pipe failure, the secondary heat pipe cavity can efficiently transfer heat from other operating primary heat pipes to the engine heat exchanger of the defunct heat pipe. Third, the secondary heat pipe vapor cavity reduces temperature drops caused by heat flow into the engine. This unique design provides a high level of reliability and performance.

Negative hydrogen ion production in a helicon plasma source

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

Santoso, J., E-mail: Jesse.Santoso@anu.edu.au; Corr, C. S.; Manoharan, R.

2015-09-15

In order to develop very high energy (>1 MeV) neutral beam injection systems for applications, such as plasma heating in fusion devices, it is necessary first to develop high throughput negative ion sources. For the ITER reference source, this will be realised using caesiated inductively coupled plasma devices, containing either hydrogen or deuterium discharges, operated with high rf input powers (up to 90 kW per driver). It has been suggested that due to their high power coupling efficiency, helicon devices may be able to reduce power requirements and potentially obviate the need for caesiation due to the high plasma densities achievable. Here,more » we present measurements of negative ion densities in a hydrogen discharge produced by a helicon device, with externally applied DC magnetic fields ranging from 0 to 8.5 mT at 5 and 10 mTorr fill pressures. These measurements were taken in the magnetised plasma interaction experiment at the Australian National University and were performed using the probe-based laser photodetachment technique, modified for the use in the afterglow of the plasma discharge. A peak in the electron density is observed at ∼3 mT and is correlated with changes in the rf power transfer efficiency. With increasing magnetic field, an increase in the negative ion fraction from 0.04 to 0.10 and negative ion densities from 8 × 10{sup 14 }m{sup −3} to 7 × 10{sup 15 }m{sup −3} is observed. It is also shown that the negative ion densities can be increased by a factor of 8 with the application of an external DC magnetic field.« less

Integrated tokamak modeling: when physics informs engineering and research planning

NASA Astrophysics Data System (ADS)

Poli, Francesca

2017-10-01

Simulations that integrate virtually all the relevant engineering and physics aspects of a real tokamak experiment are a power tool for experimental interpretation, model validation and planning for both present and future devices. This tutorial will guide through the building blocks of an ``integrated'' tokamak simulation, such as magnetic flux diffusion, thermal, momentum and particle transport, external heating and current drive sources, wall particle sources and sinks. Emphasis is given to the connection and interplay between external actuators and plasma response, between the slow time scales of the current diffusion and the fast time scales of transport, and how reduced and high-fidelity models can contribute to simulate a whole device. To illustrate the potential and limitations of integrated tokamak modeling for discharge prediction, a helium plasma scenario for the ITER pre-nuclear phase is taken as an example. This scenario presents challenges because it requires core-edge integration and advanced models for interaction between waves and fast-ions, which are subject to a limited experimental database for validation and guidance. Starting from a scenario obtained by re-scaling parameters from the demonstration inductive ``ITER baseline'', it is shown how self-consistent simulations that encompass both core and edge plasma regions, as well as high-fidelity heating and current drive source models are needed to set constraints on the density, magnetic field and heating scheme. This tutorial aims at demonstrating how integrated modeling, when used with adequate level of criticism, can not only support design of operational scenarios, but also help to asses the limitations and gaps in the available models, thus indicating where improved modeling tools are required and how present experiments can help their validation and inform research planning. Work supported by DOE under DE-AC02-09CH1146.

Two-Dimensional, Supersonic, Linearized Flow with Heat Addition

NASA Technical Reports Server (NTRS)

Lomax, Harvard

1959-01-01

Calculations are presented for the forces on a thin supersonic wing underneath which the air is heated. The analysis is limited principally to linearized theory but nonlinear effects are considered. It is shown that significant advantages to external heating would exist if the heat were added well below and ahead of the wing.

Heat pump system

DOEpatents

Swenson, Paul F.; Moore, Paul B.

1983-01-01

An air heating and cooling system for a building includes an expansion type refrigeration circuit and a vapor power circuit. The refrigeration circuit includes two heat exchangers, one of which is communicated with a source of indoor air from the building and the other of which is communicated with a source of air from outside the building. The vapor power circuit includes two heat exchangers, one of which is disposed in series air flow relationship with the indoor refrigeration circuit heat exchanger and the other of which is disposed in series air flow relationship with the outdoor refrigeration circuit heat exchanger. Fans powered by electricity generated by a vapor power circuit alternator circulate indoor air through the two indoor heat exchangers and circulate outside air through the two outdoor heat exchangers. The system is assembled as a single roof top unit, with a vapor power generator and turbine and compressor thermally insulated from the heat exchangers, and with the indoor heat exchangers thermally insulated from the outdoor heat exchangers.

Heat pump system

DOEpatents

Swenson, Paul F.; Moore, Paul B.

1977-01-01

An air heating and cooling system for a building includes an expansion type refrigeration circuit and a vapor power circuit. The refrigeration circuit includes two heat exchangers, one of which is communicated with a source of indoor air from the building and the other of which is communicated with a source of air from outside the building. The vapor power circuit includes two heat exchangers, one of which is disposed in series air flow relationship with the indoor refrigeration circuit heat exchanger and the other of which is disposed in series air flow relationship with the outdoor refrigeration circuit heat exchanger. Fans powered by electricity generated by a vapor power circuit alternator circulate indoor air through the two indoor heat exchangers and circulate outside air through the two outdoor heat exchangers. The system is assembled as a single roof top unit, with a vapor power generator and turbine and compressor thermally insulated from the heat exchangers, and with the indoor heat exchangers thermally insulated from the outdoor heat exchangers.

Heat pump system

DOEpatents

Swenson, Paul F.; Moore, Paul B.

1983-06-21

An air heating and cooling system for a building includes an expansion type refrigeration circuit and a vapor power circuit. The refrigeration circuit includes two heat exchangers, one of which is communicated with a source of indoor air from the building and the other of which is communicated with a source of air from outside the building. The vapor power circuit includes two heat exchangers, one of which is disposed in series air flow relationship with the indoor refrigeration circuit heat exchanger and the other of which is disposed in series air flow relationship with the outdoor refrigeration circuit heat exchanger. Fans powered by electricity generated by a vapor power circuit alternator circulate indoor air through the two indoor heat exchangers and circulate outside air through the two outdoor heat exchangers. The system is assembled as a single roof top unit, with a vapor power generator and turbine and compressor thermally insulated from the heat exchangers, and with the indoor heat exchangers thermally insulated from the outdoor heat exchangers.

Hydride compressor

DOEpatents

Powell, James R.; Salzano, Francis J.

1978-01-01

Method of producing high energy pressurized gas working fluid power from a low energy, low temperature heat source, wherein the compression energy is gained by using the low energy heat source to desorb hydrogen gas from a metal hydride bed and the desorbed hydrogen for producing power is recycled to the bed, where it is re-adsorbed, with the recycling being powered by the low energy heat source. In one embodiment, the adsorption-desorption cycle provides a chemical compressor that is powered by the low energy heat source, and the compressor is connected to a regenerative gas turbine having a high energy, high temperature heat source with the recycling being powered by the low energy heat source.

Experimental study on copper cathode erosion rate and rotational velocity of magnetically driven arcs in a well-type cathode non-transferred plasma torch operating in air

NASA Astrophysics Data System (ADS)

Chau, S. W.; Hsu, K. L.; Lin, D. L.; Tzeng, C. C.

2007-04-01

The cathode erosion rate, arc root velocity and output power of a well-type cathode (WTC), non-transferred plasma torch operating in air are studied experimentally in this paper. An external solenoid to generate a magnetically driven arc and a circular swirler to produce a vortex flow structure are equipped in the studied torch system, which is designed to reduce the erosion rate at the cathode. A least square technique is applied to correlate the system parameters, i.e. current, axial magnetic field and mass flow rate, with the cathode erosion rate, arc root velocity and system power output. In the studied WTC torch system, the cathode erosion has a major thermal erosion component and a minor component due to the ion-bombardment effect. The cathode erosion increases with the increase of current due to the enhancement in both Joule heating and ion bombardment. The axial magnetic field can significantly reduce the cathode erosion by reducing the thermal loading of cathode materials at the arc root and improving the heat transfer to gas near the cathode. But, the rise in the mass flow rate leads to the deterioration of erosion, since the ion-bombardment effect prevails over the convective cooling at the cathode. The most dominant system parameter to influence the arc root velocity is the axial magnetic field, which is mainly contributed to the magnetic force driving the arc. The growth in current has a negative impact on increasing the arc root velocity, because the friction force acting at the spot due to a severe molten condition becomes the dominant component counteracting the magnetic force. The mass flow rate also suppresses the arc root velocity, as a result of which the arc root moves in the direction against that of the swirled working gas. All system parameters such as current, magnetic field and gas flow rate increase with the increase in the torch output power. The experimental evidences suggest that the axial magnetic field is the most important parameter to operate the straight-polarity WTC plasma torch at high output power with a limited cathode erosion rate. This emphasizes the importance of an external magnetic field on a WTC torch system for reducing the erosion at the cathode.

Comparative study on power generation of dual-cathode microbial fuel cell according to polarization methods.

PubMed

Lee, Kang-yu; Ryu, Wyan-seuk; Cho, Sung-il; Lim, Kyeong-ho

2015-11-01

Microbial fuel cells (MFCs) exist in various forms depending on the type of pollutant to be removed and the expected performance. Dual-cathode MFCs, with their simple structure, are capable of removing both organic matter and nitrogen. Moreover, various methods are available for the collection of polarization data, which can be used to calculate the maximum power density, an important factor of MFCs. Many researchers prefer the method of varying the external resistance in a single-cycle due to the short measurement time and high accuracy. This study compared power densities of dual-cathode MFCs in a single-cycle with values calculated over multi-cycles to determine the optimal polarization method. External resistance was varied from high to low and vice versa in the single-cycle, to calculate power density. External resistance was organized in descending order with initial start-up at open circuit voltage (OCV), and then it was organized in descending order again after the initial start-up at 1000 Ω. As a result, power density was underestimated at the anoxic cathode when the external resistance was varied from low to high, and overestimated at the aerobic cathode and anoxic cathode when external resistance at OCV was reduced following initial start-up. In calculating the power densities of dual-cathode MFCs, this paper recommends the method of gradually reducing the external resistance after initial start-up with high external resistance. Copyright © 2015 Elsevier Ltd. All rights reserved.

Results of aeroheating DFI and ET design-data test on a 0.0175-scale model 60-OTS conducted in the Von Karman Gas Dynamics Facility (VKF) 40" supersonic and the 50" hypersonic wind tunnels A and C

NASA Technical Reports Server (NTRS)

Marroquin, J.; Leef, C. R.

1985-01-01

The 0.0175-scale thin-skin thermocouple Model 60-OTS was tested in the von Karman Gas Facility 40-inch continuous flow supersonic tunnel A and the VKF Tunnel C. Testing was conducted at Mach numbers 2.25 to 4.0, and Reynolds numbers from 0.4 x 10 to the 6th power/ft to 6.6 x 10 to the 6th power/ft. Angle of attack range was from -5.0 to +5.0 degrees, and angle of sideslip range was from -6 to +6 degrees. The primary objective of this test was to provide a valid base for the external tank (ET) and solid rocket booster (SRB) heating prediction methodology for ascent flight by taking heating data at Development Flight Instrumentation (DFI) locations for flight conditions simulating STS-1 through -4. A second objective was to obtain additional aeroheating data to support potential reduction of the thermal protection system (TPS) on the ET. The third phase of the test was funded and conducted by NASA/MSFC for the purpose of establishing confidence in the data base from the lower temperature tunnel A.

KSC-2011-6662

NASA Image and Video Library

2011-06-30

CAPE CANAVERAL, Fla. -- In the high bay of the RTG storage facility at NASA's Kennedy Space Center in Florida, Department of Energy contractor employees remove the external and internal protective layers of the shipping cask enclosing the multi-mission radioisotope thermoelectric generator (MMRTG) for NASA's Mars Science Laboratory mission. The MMRTG will generate the power needed for the mission from the natural decay of plutonium-238, a non-weapons-grade form of the radioisotope. Heat given off by this natural decay will provide constant power through the day and night during all seasons. Waste heat from the MMRTG will be circulated throughout the rover system to keep instruments, computers, mechanical devices and communications systems within their operating temperature ranges. MSL's components include a compact car-sized rover, Curiosity, which has 10 science instruments designed to search for evidence on whether Mars has had environments favorable to microbial life, including chemical ingredients for life. The unique rover will use a laser to look inside rocks and release its gasses so that the rover’s spectrometer can analyze and send the data back to Earth. Launch of MSL aboard a United Launch Alliance Atlas V rocket is scheduled for Nov. 25 from Space Launch Complex 41 on Cape Canaveral Air Force Station in Florida. For more information, visit http://www.nasa.gov/msl. Photo credit: NASA/Frankie Martin

KSC-2011-6663

NASA Image and Video Library

2011-06-30

CAPE CANAVERAL, Fla. -- In the high bay of the RTG storage facility at NASA's Kennedy Space Center in Florida, the external and internal protective layers of the shipping cask are lifted from around the multi-mission radioisotope thermoelectric generator (MMRTG) for NASA's Mars Science Laboratory mission. The MMRTG will generate the power needed for the mission from the natural decay of plutonium-238, a non-weapons-grade form of the radioisotope. Heat given off by this natural decay will provide constant power through the day and night during all seasons. Waste heat from the MMRTG will be circulated throughout the rover system to keep instruments, computers, mechanical devices and communications systems within their operating temperature ranges. MSL's components include a compact car-sized rover, Curiosity, which has 10 science instruments designed to search for evidence on whether Mars has had environments favorable to microbial life, including chemical ingredients for life. The unique rover will use a laser to look inside rocks and release its gasses so that the rover’s spectrometer can analyze and send the data back to Earth. Launch of MSL aboard a United Launch Alliance Atlas V rocket is scheduled for Nov. 25 from Space Launch Complex 41 on Cape Canaveral Air Force Station in Florida. For more information, visit http://www.nasa.gov/msl. Photo credit: NASA/Frankie Martin

75 FR 16957 - Energy Conservation Program: Test Procedures for Battery Chargers and External Power Supplies

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-02

... Procedures C. Review of Single-Voltage External Power Supply Test Procedure D. Multiple-Voltage External...) Deletions of Existing Definitions (b) Revisions to Existing Definitions (c) Additions of New Definitions 4. Test Apparatus and General Instructions (a) Confidence Intervals (b) Temperature (c) AC Input Voltage...

Calculating the Effect of External Shading on the Solar Heat Gain Coefficient of Windows

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

Kohler, Christian; Shukla, Yash; Rawal, Rajan

Current prescriptive building codes have limited ways to account for the effect of solar shading, such as overhangs and awnings, on window solar heat gains. We propose two new indicators, the adjusted Solar Heat Gain Coefficient (aSHGC) which accounts for external shading while calculating the SHGC of a window, and a weighted SHGC (SHGCw) which provides a seasonal SHGC weighted by solar intensity. We demonstrate a method to calculate these indices using existing tools combined with additional calculations. The method is demonstrated by calculating the effect of an awning on a clear double glazing in New Delhi.

Adaptive Heat Engine.

PubMed

Allahverdyan, A E; Babajanyan, S G; Martirosyan, N H; Melkikh, A V

2016-07-15

A major limitation of many heat engines is that their functioning demands on-line control and/or an external fitting between the environmental parameters (e.g., temperatures of thermal baths) and internal parameters of the engine. We study a model for an adaptive heat engine, where-due to feedback from the functional part-the engine's structure adapts to given thermal baths. Hence, no on-line control and no external fitting are needed. The engine can employ unknown resources; it can also adapt to results of its own functioning that make the bath temperatures closer. We determine resources of adaptation and relate them to the prior information available about the environment.

A Comprehensive Model of Electric-Field-Enhanced Jumping-Droplet Condensation on Superhydrophobic Surfaces.

PubMed

Birbarah, Patrick; Li, Zhaoer; Pauls, Alexander; Miljkovic, Nenad

2015-07-21

Superhydrophobic micro/nanostructured surfaces for dropwise condensation have recently received significant attention due to their potential to enhance heat transfer performance by shedding positively charged water droplets via coalescence-induced droplet jumping at length scales below the capillary length and allowing the use of external electric fields to enhance droplet removal and heat transfer, in what has been termed electric-field-enhanced (EFE) jumping-droplet condensation. However, achieving optimal EFE conditions for enhanced heat transfer requires capturing the details of transport processes that is currently lacking. While a comprehensive model has been developed for condensation on micro/nanostructured surfaces, it cannot be applied for EFE condensation due to the dynamic droplet-vapor-electric field interactions. In this work, we developed a comprehensive physical model for EFE condensation on superhydrophobic surfaces by incorporating individual droplet motion, electrode geometry, jumping frequency, field strength, and condensate vapor-flow dynamics. As a first step toward our model, we simulated jumping droplet motion with no external electric field and validated our theoretical droplet trajectories to experimentally obtained trajectories, showing excellent temporal and spatial agreement. We then incorporated the external electric field into our model and considered the effects of jumping droplet size, electrode size and geometry, condensation heat flux, and droplet jumping direction. Our model suggests that smaller jumping droplet sizes and condensation heat fluxes require less work input to be removed by the external fields. Furthermore, the results suggest that EFE electrodes can be optimized such that the work input is minimized depending on the condensation heat flux. To analyze overall efficiency, we defined an incremental coefficient of performance and showed that it is very high (∼10(6)) for EFE condensation. We finally proposed mechanisms for condensate collection which would ensure continuous operation of the EFE system and which can scalably be applied to industrial condensers. This work provides a comprehensive physical model of the EFE condensation process and offers guidelines for the design of EFE systems to maximize heat transfer.

Understanding and Controlling Lignocellulosic Pyrolysis for the Production of Renewable Fuel and Chemical Precursors

NASA Astrophysics Data System (ADS)

Pecha, Michael Brennan

Pyrolysis is a technology for producing fuels, chemicals, and engineered carbons from renewable feedstocks like lignocellulosic biomass. This work aims to address some of the scientific and technical hurdles that need to be overcome to control the products of pyrolysis. The first section aims to address knowledge gaps regarding primary pyrolysis reactions; in this study, pine wood was acid washed and small amounts of acid were impregnated into the biomass prior to pyrolysis. Results showed that the acid mitigated fragmentation reactions caused by residual metals and had further effect on production of sugars and oligomeric lignin products. The next section aims to address knowledge gaps regarding what reactions occur in the liquid intermediate phase in biomass pyrolysis; in these studies, a novel reactor system was built which could perform thin film fast pyrolysis studies at different pressures from 4 mbar to 1 atm with cellulose, milled wood lignin, and hybrid poplar wood. The reactor was carefully characterized to achieve comparable data between the different pressures. The use of vacuum allowed for control of the residence time of cellobiosan (one of cellulose oligomeric products) in the liquid intermediate. In the vacuum cellulose pyrolysis studies, a high resolution FT-ICR-MS was used for the first time to explore reaction chemistry for this system. The Van-Krevelen diagram of the resulting oligomeric products proved to be a powerful tool to study secondary reactions in the liquid intermediate. Our results show that the secondary reactions in the liquid intermediate are dominated by dehydration, fragmentation, and cross-linking reactions. The final section aims to address single particle external heat transfer problems; in this study, 500 microm long particles of pine and aspen poplar with realistic pore and surface morphologies were modeled in COMSOL to determine how microstructure effects the external heat transfer coefficients in the laminar flow regime. Results showed that microstructure did indeed affect heat transfer and that heat transfer correlations based on basic geometric shapes (sphere, cylinder, slab) were not accurate enough to estimate heat transfer coefficient for the conditions studied.

Space station thermal control surfaces. [space radiators

NASA Technical Reports Server (NTRS)

Maag, C. R.; Millard, J. M.; Jeffery, J. A.; Scott, R. R.

1979-01-01

Mission planning documents were used to analyze the radiator design and thermal control surface requirements for both space station and 25-kW power module, to analyze the missions, and to determine the thermal control technology needed to satisfy both sets of requirements. Parameters such as thermal control coating degradation, vehicle attitude, self eclipsing, variation in solar constant, albedo, and Earth emission are considered. Four computer programs were developed which provide a preliminary design and evaluation tool for active radiator systems in LEO and GEO. Two programs were developed as general programs for space station analysis. Both types of programs find the radiator-flow solution and evaluate external heat loads in the same way. Fortran listings are included.

Schemes for efficient QW pumping of AlGaInP disk lasers

NASA Astrophysics Data System (ADS)

Brauch, Uwe; Mateo, Cherry May N.; Kahle, Hermann; Bek, Roman; Jetter, Michael; Abdou Ahmed, Marwan; Michler, Peter; Graf, Thomas

2017-02-01

Keys to high-power operation of disk lasers are a thin active layer, a small Stokes shift and an efficient cooling, best realized with a limited number of QWs which are pumped close to the laser wavelength and which are in close contact with one or two diamond heat sinks. To get sufficient pump absorption many passes of the pump radiation are needed. This can be realized either by taking advantage of intrinsic resonances (designed for the pump radiation) or by an external multi-pass optics (known from Yb disk lasers) or a combination of both. The various options will be discussed and some results for AlGaInP disk lasers will be presented.

Physical activity, muscle, and the HSP70 response.

PubMed

Kilgore, J L; Musch, T I; Ross, C R

1998-06-01

Selye (1936) described how organisms react to various external stimuli (i.e., stressors). These reactions generally follow a programmed series of events and help the organism adapt to the imposed stress. The heat shock response is a common cellular reaction to external stressors, including physical activity. A characteristic set of proteins is synthesised shortly after the organism is exposed to stress. Researchers have not determined how heat shock proteins affect the exercise response. However, their role in adaptation to exercise and training might be inferred, since the synthetic patterns correlate well with the stress adaptation syndrome that Selye described. This review addresses the 70 kilodalton heat shock protein family (HSP70), the most strongly induced heat shock proteins. This paper provides an overview of the general heat shock response and a brief review of literature on HSP70 function, structure, regulation, and potential applications. Potential applications in health, exercise, and medicine are provided.

Heat Rejection Concepts for Lunar Fission Surface Power Applications

NASA Technical Reports Server (NTRS)

Siamidis, John

2006-01-01

This paper describes potential heat rejection design concepts for lunar surface Brayton power conversion systems. Brayton conversion systems are currently under study by NASA for surface power applications. Surface reactors may be used for the moon to power human outposts enabling extended stays and closed loop life support. The Brayton Heat Rejection System (HRS) must dissipate waste heat generated by the power conversion system due to inefficiencies in the thermal-to-electric conversion process. Space Brayton conversion system designs tend to optimize at efficiencies of about 20 to 25 percent with radiator temperatures in the 400 K to 600 K range. A notional HRS was developed for a 100 kWe-class Brayton power system that uses a pumped water heat transport loop coupled to a water heat pipe radiator. The radiator panels employ a tube and fin construction consisting of regularly-spaced circular heat pipes contained within two composite facesheets. The water heat pipes interface to the coolant through curved sections partially contained within the cooling loop. The paper evaluates various design parameters including radiator panel orientation, coolant flow path, and facesheet thickness. Parameters were varied to compare design options on the basis of H2O pump pressure rise and required power, heat pipe unit power and radial flux, radiator area, radiator panel areal mass, and overall HRS mass.

CFD Analysis of Hypersonic Flowfields With Surface Thermochemistry and Ablation

NASA Technical Reports Server (NTRS)

Henline, W. D.

1997-01-01

In the past forty years much progress has been made in computational methods applied to the solution of problems in spacecraft hypervelocity flow and heat transfer. Although the basic thermochemical and physical modeling techniques have changed little in this time, several orders of magnitude increase in the speed of numerically solving the Navier-Stokes and associated energy equations have been achieved. The extent to which this computational power can be applied to the design of spacecraft heat shields is dependent on the proper coupling of the external flow equations to the boundary conditions and governing equations representing the thermal protection system in-depth conduction, pyrolysis and surface ablation phenomena. A discussion of the techniques used to do this in past problems as well as the current state-of-art is provided. Specific examples, including past missions such as Galileo, together with the more recent case studies of ESA/Rosetta Sample Comet Return, Mars Pathfinder and X-33 will be discussed. Modeling assumptions, design approach and computational methods and results are presented.

Study on the thermodynamical and mechanical conditions for the generation of high operating pressures with liquefied gases for low and very low flow rates

NASA Astrophysics Data System (ADS)

Nieratschker, Willi

1989-12-01

An investigation of the thermodynamical and mechanical conditions for extending the flow rate range in the direction of low flow rates with regard to the delivery of liquefied gases at high operating pressures is presented. For low flow rates, the especially critical cavitation problem connected with the pumping of liquefied gases becomes more acute, since with decreasing volume the ratio of heat losses to the hydraulic power becomes ever more unfavorable. A first prototype is designed, produced and investigated to evaluate design-related heat loss and piston seal problems. An approach to the solution is indicated for both problem areas with the application of a new and patented pump principle, and through investigation of a second prototype modified in several respects. By reducing the pump mass when designing the second pump prototype, the nonstationary cooling phase is greatly shortened, so that intermittent pump operation becomes possible when the pump is housed external to the storage tank.

Synthesis, characterization and electrochemical performances of LiFePO4/graphene cathode material for high power lithium-ion batteries

NASA Astrophysics Data System (ADS)

Shang, Weili; Kong, Lingyong; Ji, Xuewen

2014-12-01

LiFePO4/graphene (LiFePO4/G) cathode with exciting electrochemical performance was successfully synthesized by liquid phase method. LiFePO4 nanoparticles wrapped with multi-layered grapheme can be fabricated in a short time. This method did not need external heating source. Heat generated by chemical reaction conduct the process and removed the solvent simultaneously. The LiFePO4/G were analyzed by X-ray diffraction (XRD) analysis, scanning electron microscope (SEM), transmission electron microscopy (TEM), magnetic properties analysis and electrochemical performance tests. The LiFePO4/G delivered a capacity of 160 mAh g-1 at 0.1C and could tolerate various dis-charge currents with a capacity retention rate of 99.8%, 99.2%, 99.0%, 98.6%, 97.3% and 95.0% after stepwise under 5C, 10C, 15C, 20C, 25C and 30C, respectively.

A latchable thermally activated phase change actuator for microfluidic systems

NASA Astrophysics Data System (ADS)

Richter, Christiane; Sachsenheimer, Kai; Rapp, Bastian E.

2016-03-01

Complex microfluidic systems often require a high number of individually controllable active components like valves and pumps. In this paper we present the development and optimization of a latchable thermally controlled phase change actuator which uses a solid/liquid phase transition of a phase change medium and the displacement of the liquid phase change medium to change and stabilize the two states of the actuator. Because the phase change is triggered by heat produced with ohmic resistors the used control signal is an electrical signal. In contrast to pneumatically activated membrane valves this concept allows the individual control of several dozen actuators with only two external pressure lines. Within this paper we show the general working principle of the actuator and demonstrate its general function and the scalability of the concept at an example of four actuators. Additionally we present the complete results of our studies to optimize the response behavior of the actuator - the influence of the heating power as well as the used phase change medium on melting and solidifying times.

Consideration of Thermoelectric Power Generation by Using Hot Spring Thermal Energy or Industrial Waste Heat

NASA Astrophysics Data System (ADS)

Sasaki, Keiichi; Horikawa, Daisuke; Goto, Koichi

2015-01-01

Today, we face some significant environmental and energy problems such as global warming, urban heat island, and the precarious balance of world oil supply and demand. However, we have not yet found a satisfactory solution to these problems. Waste heat recovery is considered to be one of the best solutions because it can improve energy efficiency by converting heat exhausted from plants and machinery to electric power. This technology would also prevent atmospheric temperature increases caused by waste heat, and decrease fossil fuel consumption by recovering heat energy, thus also reducing CO2 emissions. The system proposed in this research generates electric power by providing waste heat or unharnessed thermal energy to built-in thermoelectric modules that can convert heat into electric power. Waste heat can be recovered from many places, including machinery in industrial plants, piping in electric power plants, waste incineration plants, and so on. Some natural heat sources such as hot springs and solar heat can also be used for this thermoelectric generation system. The generated power is expected to be supplied to auxiliary machinery around the heat source, stored as an emergency power supply, and so on. The attributes of this system are (1) direct power generation using hot springs or waste heat; (2) 24-h stable power generation; (3) stand-alone power system with no noise and no vibration; and (4) easy maintenance attributed to its simple structure with no moving parts. In order to maximize energy use efficiency, the temperature difference between both sides of the thermoelectric (TE) modules built into the system need to be kept as large as possible. This means it is important to reduce thermal resistance between TE modules and heat source. Moreover, the system's efficiency greatly depends on the base temperature of the heat sources and the material of the system's TE modules. Therefore, in order to make this system practical and efficient, it is necessary to choose the heat source first and then design the most appropriate structure for the source by applying analytical methods. This report describes how to design a prototype of a thermoelectric power generator using the analytical approach and the results of performance evaluation tests carried out in the field.

Coal fired air turbine cogeneration

NASA Astrophysics Data System (ADS)

Foster-Pegg, R. W.

Fuel options and generator configurations for installation of cogenerator equipment are reviewed, noting that the use of oil or gas may be precluded by cost or legislation within the lifetime of any cogeneration equipment yet to be installed. A coal fueled air turbine cogenerator plant is described, which uses external combustion in a limestone bed at atmospheric pressure and in which air tubes are sunk to gain heat for a gas turbine. The limestone in the 26 MW unit absorbs sulfur from the coal, and can be replaced by other sorbents depending on types of coal available and stringency of local environmental regulations. Low temperature combustion reduces NOx formation and release of alkali salts and corrosion. The air heat is exhausted through a heat recovery boiler to produce process steam, then can be refed into the combustion chamber to satisfy preheat requirements. All parts of the cogenerator are designed to withstand full combustion temperature (1500 F) in the event of air flow stoppage. Costs are compared with those of a coal fired boiler and purchased power, and it is shown that the increased capital requirements for cogenerator apparatus will yield a 2.8 year payback. Detailed flow charts, diagrams and costs schedules are included.

Controlling Thermal Conduction by Graded Materials

NASA Astrophysics Data System (ADS)

Ji, Qin; Huang, Ji-Ping

2018-04-01

Manipulating thermal conductivities are fundamentally important for controlling the conduction of heat at will. Thermal cloaks and concentrators, which have been extensively studied recently, are actually graded materials designed according to coordinate transformation approaches, and their effective thermal conductivity is equal to that of the host medium outside the cloak or concentrator. Here we attempt to investigate a more general problem: what is the effective thermal conductivity of graded materials? In particular, we perform a first-principles approach to the analytic exact results of effective thermal conductivities of materials possessing either power-law or linear gradation profiles. On the other hand, by solving Laplace’s equation, we derive a differential equation for calculating the effective thermal conductivity of a material whose thermal conductivity varies along the radius with arbitrary gradation profiles. The two methods agree with each other for both external and internal heat sources, as confirmed by simulation and experiment. This work provides different methods for designing new thermal metamaterials (including thermal cloaks and concentrators), in order to control or manipulate the transfer of heat. Support by the National Natural Science Foundation of China under Grant No. 11725521, by the Science and Technology Commission of Shanghai Municipality under Grant No. 16ZR1445100

Lock-in thermography as a rapid and reproducible thermal characterization method for magnetic nanoparticles

NASA Astrophysics Data System (ADS)

Lemal, Philipp; Geers, Christoph; Monnier, Christophe A.; Crippa, Federica; Daum, Leopold; Urban, Dominic A.; Rothen-Rutishauser, Barbara; Bonmarin, Mathias; Petri-Fink, Alke; Moore, Thomas L.

2017-04-01

Lock-in thermography (LIT) is a sensitive imaging technique generally used in engineering and materials science (e.g. detecting defects in composite materials). However, it has recently been expanded for investigating the heating power of nanomaterials, such as superparamagnetic iron oxide nanoparticles (SPIONs). Here we implement LIT as a rapid and reproducible method that can evaluate the heating potential of various sizes of SPIONs under an alternating magnetic field (AMF), as well as the limits of detection for each particle size. SPIONs were synthesized via thermal decomposition and stabilized in water via a ligand transfer process. Thermographic measurements of SPIONs were made by stimulating particles of varying sizes and increasing concentrations under an AMF. Furthermore, a commercially available SPION sample was included as an external reference. While the size dependent heating efficiency of SPIONs has been previously described, our objective was to probe the sensitivity limits of LIT. For certain size regimes it was possible to detect signals at concentrations as low as 0.1 mg Fe/mL. Measuring at different concentrations enabled a linear regression analysis and extrapolation of the limit of detection for different size nanoparticles.

Heat-Pipe-Associated Localized Thermoelectric Power Generation System

NASA Astrophysics Data System (ADS)

Kim, Pan-Jo; Rhi, Seok-Ho; Lee, Kye-Bock; Hwang, Hyun-Chang; Lee, Ji-Su; Jang, Ju-Chan; Lee, Wook-Hyun; Lee, Ki-Woo

2014-06-01

The present study focused on how to improve the maximum power output of a thermoelectric generator (TEG) system and move heat to any suitable space using a TEG associated with a loop thermosyphon (loop-type heat pipe). An experimental study was carried out to investigate the power output, the temperature difference of the thermoelectric module (TEM), and the heat transfer performance associated with the characteristic of the researched heat pipe. Currently, internal combustion engines lose more than 35% of their fuel energy as recyclable heat in the exhaust gas, but it is not easy to recycle waste heat using TEGs because of the limited space in vehicles. There are various advantages to use of TEGs over other power sources, such as the absence of moving parts, a long lifetime, and a compact system configuration. The present study presents a novel TEG concept to transfer heat from the heat source to the sink. This technology can transfer waste heat to any location. This simple and novel design for a TEG can be applied to future hybrid cars. The present TEG system with a heat pipe can transfer heat and generate power of around 1.8 V with T TEM = 58°C. The heat transfer performance of a loop-type heat pipe with various working fluids was investigated, with water at high heat flux (90 W) and 0.05% TiO2 nanofluid at low heat flux (30 W to 70 W) showing the best performance in terms of power generation. The heat pipe can transfer the heat to any location where the TEM is installed.

Heat transfer in a tank with a cryogenic fluid under conditions of external heating

NASA Astrophysics Data System (ADS)

Notkin, V. L.

Heat transfer in the gas layer of a horizontal cylindrical tank with a fluctuating level of boiling liquid nitrogen is investigated experimentally. Criterial equations for heat transfer in the gas cavity of the tank are obtained. A procedure is proposed for calculating heat fluxes, temperature fields, and cryogenic fluid evaporation during the filling and draining of the tank.

An Investigation Utilizing an Electrical Analogue of Cyclic Deicing of a Hollow Steel Propeller with an External Blade Shoe

NASA Technical Reports Server (NTRS)

Neel, Carr B., Jr.

1952-01-01

A study has been made of the heat requirement for the cyclic de-icing of hollow steel propellers fitted with external blade heating shoes. Solutions to the equations for the heat flow in cyclic heating of propellers were obtained, using an electrical analogy. The study showed how the energy requirement for propeller de-icing with existing blade shoes could be decreased, and illustrated the effect of blade-shoe design on the energy requirement. It was demonstrated, for example, that by increasing the heating intensity and decreasing the heating period from those currently used the energy requirement could be decreased in the order of 60 percent. ' In addition, ft was shown that heating requirements could be decreased further, by as much as 60 percent, through proper design of the shoes. The' investigation also showed the energy requirement to increase with decreasing liquid-water content and air temperature. Uncertainties as to the exact values of convective heat-transfer coefficient prevailing over the surface of the blade and ice layer resulted in uncertainties of approximately proportional magnitude in the values of required heating intensity.

High-Temperature Electronics: A Role for Wide Bandgap Semiconductors?

NASA Technical Reports Server (NTRS)

Neudeck, Philip G.; Okojie, Robert S.; Chen, Liang-Yu

2002-01-01

It is increasingly recognized that semiconductor based electronics that can function at ambient temperatures higher than 150 C without external cooling could greatly benefit a variety of important applications, especially-in the automotive, aerospace, and energy production industries. The fact that wide bandgap semiconductors are capable of electronic functionality at much higher temperatures than silicon has partially fueled their development, particularly in the case of SiC. It appears unlikely that wide bandgap semiconductor devices will find much use in low-power transistor applications until the ambient temperature exceeds approximately 300 C, as commercially available silicon and silicon-on-insulator technologies are already satisfying requirements for digital and analog very large scale integrated circuits in this temperature range. However, practical operation of silicon power devices at ambient temperatures above 200 C appears problematic, as self-heating at higher power levels results in high internal junction temperatures and leakages. Thus, most electronic subsystems that simultaneously require high-temperature and high-power operation will necessarily be realized using wide bandgap devices, once the technology for realizing these devices become sufficiently developed that they become widely available. Technological challenges impeding the realization of beneficial wide bandgap high ambient temperature electronics, including material growth, contacts, and packaging, are briefly discussed.

Sodium heat pipe use in solar Stirling power conversion systems

NASA Astrophysics Data System (ADS)

Zimmerman, W. F.; Divakaruni, S. M.; Won, Y. S.

1980-08-01

Sodium heat pipes were selected for use as a thermal transport method in a focus-mounted, distributed concentrator solar Stirling power conversion system intended to produce 15-20 kWe per unit. Heat pipes were used both to receive thermal power in the solar receiver and to transmit it to a secondary heat pipe containing both latent heat salt (for up to 1.25 hours of thermal storage) and the heat exchanger of the Stirling engine. Experimental tests were performed on five solar receiver heat pipes with various internal wicking configurations. The performance of the heat pipes at various power levels and operating attitudes was investigated at temperatures near 1550 F; the unidirectional heat transfer in these heat pipes was demonstrated in normal operating attitudes and particularly in the inverted position required during overnight stowage of the concentrator.

Sodium heat pipe use in solar Stirling power conversion systems

NASA Technical Reports Server (NTRS)

Zimmerman, W. F.; Divakaruni, S. M.; Won, Y. S.

1980-01-01

Sodium heat pipes were selected for use as a thermal transport method in a focus-mounted, distributed concentrator solar Stirling power conversion system intended to produce 15-20 kWe per unit. Heat pipes were used both to receive thermal power in the solar receiver and to transmit it to a secondary heat pipe containing both latent heat salt (for up to 1.25 hours of thermal storage) and the heat exchanger of the Stirling engine. Experimental tests were performed on five solar receiver heat pipes with various internal wicking configurations. The performance of the heat pipes at various power levels and operating attitudes was investigated at temperatures near 1550 F; the unidirectional heat transfer in these heat pipes was demonstrated in normal operating attitudes and particularly in the inverted position required during overnight stowage of the concentrator.

Heat Pipes Cool Power Magnetics

NASA Technical Reports Server (NTRS)

Hansen, I.; Chester, M.; Luedke, E.

1983-01-01

Configurations originally developed for space use are effective in any orientation. Heat pipes integrated into high-power, high-frequency, highvoltage spaceflight magnetics reduce weight and improve reliability by lowering internal tempertures. Two heat pipes integrated in design of power transformer cool unit in any orientation. Electrostatic shield conducts heat from windings to heat pipe evaporator. Technology allows dramatic reductions in size and weight, while significantly improving reliability. In addition, all attitude design of heat pipes allows operation of heat pipes independent of local gravity forces.

Quantity, Quality, and Availability of Waste Heat from United States Thermal Power Generation.

PubMed

Gingerich, Daniel B; Mauter, Meagan S

2015-07-21

Secondary application of unconverted heat produced during electric power generation has the potential to improve the life-cycle fuel efficiency of the electric power industry and the sectors it serves. This work quantifies the residual heat (also known as waste heat) generated by U.S. thermal power plants and assesses the intermittency and transport issues that must be considered when planning to utilize this heat. Combining Energy Information Administration plant-level data with literature-reported process efficiency data, we develop estimates of the unconverted heat flux from individual U.S. thermal power plants in 2012. Together these power plants discharged an estimated 18.9 billion GJ(th) of residual heat in 2012, 4% of which was discharged at temperatures greater than 90 °C. We also characterize the temperature, spatial distribution, and temporal availability of this residual heat at the plant level and model the implications for the technical and economic feasibility of its end use. Increased implementation of flue gas desulfurization technologies at coal-fired facilities and the higher quality heat generated in the exhaust of natural gas fuel cycles are expected to increase the availability of residual heat generated by 10.6% in 2040.

The heat supply system for a self-contained dwelling house on the basis of a heat pump and wind power installation

NASA Astrophysics Data System (ADS)

Chemekov, V. V.; Kharchenko, V. V.

2013-03-01

Matters concerned with setting up environmentally clean supply of heat to dwelling houses in the resort zone of the Russian Black Sea coast on the basis of air-water type heat pumps powered from wind power installations are discussed. The investigations were carried out as applied to the system supplying heat for an individual dwelling house with an area of around 300 m2 situated in the Tuapse city. The design heat load of the building's heating system is around 8.3 kW. The Viessmann Vitocal 300 AW pump is chosen as the main source of heat supply, and a 4-kW electric heater built into a storage tank is chosen as a standby source. The selected wind power installation (the EuroWind 10 unit) has a power capacity of 13 kWe.

Research of waste heat energy efficiency for absorption heat pump recycling thermal power plant circulating water

NASA Astrophysics Data System (ADS)

Zhang, Li; Zhang, Yu; Zhou, Liansheng; E, Zhijun; Wang, Kun; Wang, Ziyue; Li, Guohao; Qu, Bin

2018-02-01

The waste heat energy efficiency for absorption heat pump recycling thermal power plant circulating water has been analyzed. After the operation of heat pump, the influences on power generation and heat generation of unit were taken into account. In the light of the characteristics of heat pump in different operation stages, the energy efficiency of heat pump was evaluated comprehensively on both sides of benefits belonging to electricity and benefits belonging to heat, which adopted the method of contrast test. Thus, the reference of energy efficiency for same type projects was provided.

A multi-state magnetic memory dependent on the permeability of Metglas

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

Petrie, J. R.; Wieland, K. A.; Timmerwilke, J. M.

A three-state magnetic memory was developed based on differences in the magnetic permeability of a soft ferromagnetic media, Metglas 2826MB (Fe{sub 40}Ni{sub 38}Mo{sub 4}B{sub 18}). By heating bits of a 250 nm thick Metglas film with 70–100 mW of laser power, we were able to tune the local microstructure, and hence, the permeability. Ternary memory states were created by using lower laser power to enhance the initial permeability through localized atomic rearrangement and higher power to reduce the permeability through crystallization. The permeability of the bits was read by detecting variations in an external 32 Oe probe field within 10 μm ofmore » the media via a magnetic tunnel junction read head. Compared to data based on remanent magnetization, these multi-permeability bits have enhanced insensitivity to unexpected field and temperature changes. We found that data was not corrupted after exposure to fields of 1 T or temperatures of 423 K, indicating the effectiveness of this multi-state approach for safely storing large amounts of data.« less

Effect of Spacecraft Environmental Variables on the Flammability of Fire Resistant Fabrics

NASA Astrophysics Data System (ADS)

Osorio, A. F.; Fernandez-Pello, C.; Takahashi, S.; Rodriguez, J.; Urban, D. L.; Ruff, G.

2012-01-01

Fire resistant fabrics are used for firefighter, racecar drivers as well as astronaut suits. However, their fire resistant characteristics depend on the environment conditions and require study. Particularly important is the response of these fabrics to elevated oxygen concentration environments and radiant heat from a source such as an adjacent fire. In this work, experiments using two fire resistant fabrics were conducted to study the effect of oxygen concentration, external radiant flux and oxidizer flow velocity in concurrent flame spread. Results show that for a given fabric the minimum oxygen concentration for flame spread depends strongly on the magnitude of the external radiant flux. At increased oxygen concentrations the external radiant flux required for flame spread decreases. Oxidizer flow velocity influences the external radiant flux only when the convective heat flux from the flame has similar values to the external radiant flux. The results of this work provide further understanding of the flammability characteristics of fire resistant fabrics in environments similar to those of future spacecrafts.

Modeling the pyrolysis study of non-charring polymers under reduced pressure environments

NASA Astrophysics Data System (ADS)

Zong, Ruowen; Kang, Ruxue; Hu, Yanghui; Zhi, Youran

2018-04-01

In order to study the pyrolysis of non-charring polymers under reduced pressure environments, a series of experiments based on black acrylonitrile butadiene styrene (ABS) was conducted in a reduced pressure chamber under different external heat fluxes. The temperatures of the top surface and the bottom of the sample and the mass loss during the whole process were measured in real time. A one-dimensional numerical model was developed to predict the top surface and the bottom surface temperatures of ABS during the pyrolysis at different reduced pressures and external heat fluxes, and the model was validated by the experimental data. The results of the study indicate that the profiles of the top surface and the bottom surface temperatures are different at different pressures and heat fluxes. The temperature and the mass loss rate of the sample under a lower heat flux decreased significantly as the pressure was increased. However, under a higher heat flux, the temperature and the mass loss rate showed little sensitivity to the pressure. The simulated results fitted the experimental results better at the higher heat flux than at the lower heat flux.

Development of a high permeability cored transintegumental power transformer.

PubMed

Helmicki, A J; Melvin, D M; Henderson, H T; Nebrigic, D; Venkat, R; Glos, D L

1996-01-01

Circulatory support devices require 10-20 W. Currently, several devices are under development for the transmission of this power via transcutaneous transformers, with the secondary implanted subcutaneously and the primary worn externally. Because these devices are air cored, they have relatively large, bulky external appliances, poor coil to coil coupling, and result in significant stray fields passing through adjacent tissues. This article reports on the engineering design of a novel, high permeability cored transformer implanted in a transenteric configuration using an isolated intestinal pouch. Such an approach offers greater energy transmission efficiency, less heat dissipation, less stray electromagnetic energy, and greatly reduced device size. Two competing designs using this concept have been developed and tested. Each consists of the transformer, together with power interface electronics, forming a direct current (DC)/DC resonant converter. Operating frequencies are 90.2 and 14.7 kHz, respectively, with primary/secondary turns ratios of 10/10 and 11/14, respectively. In addition, data interface electronics allows communication across the transformer of up to four signals at a per channel sample rate of 10 Hz. Both designs are able to continuously transmit 25 W at an output level of 12 Vdc into a 5.8 omega load. Calorimetry tests indicate DC to DC efficiencies greater than 75% and coil to coil efficiencies greater than 96%. Total package size for the implantable portion of each device (including sensor internal interface electronics) is less than 40 ml, with a weight weight of less than 100 g. The results of short-term implantation studies have been favorable. Long-term implantation studies currently are under way.

Electrical heating of soils using high efficiency electrode patterns and power phases

DOEpatents

Buettner, Harley M.

1999-01-01

Powerline-frequency electrical (joule) heating of soils using a high efficiency electrode configuration and power phase arrangement. The electrode configuration consists of several heating or current injection electrodes around the periphery of a volume of soil to be heated, all electrodes being connected to one phase of a multi-phase or a single-phase power system, and a return or extraction electrode or electrodes located inside the volume to be heated being connected to the remaining phases of the multi-phase power system or to the neutral side of the single-phase power source. This electrode configuration and power phase arrangement can be utilized anywhere where powerline frequency soil heating is applicable and thus has many potential uses including removal of volatile organic compounds such as gasoline and tricholorethylene (TCE) from contaminated areas.

Ultra clean burner for an AMTEC system suitable for hybrid electric vehicles

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

Mital, R.; Sievers, R.K.; Hunt, T.K.

1997-12-31

High power Alkali Metal Thermal to Electric Converter (AMTEC) systems have the potential to make the hybrid electric vehicle (HEV) program a success by meeting the challenging standards put forth by the EPA for the automobile industry. The premise of the whole concept of using AMTEC cells, as discussed by Hunt et al. (1995), for power generation in HEV`s is based on the utilization of a high efficiency external combustion system. The key requirement being a burner which will produce extremely low quantities of carbon monoxide and oxides of nitrogen, emit minimal amounts of hydrocarbon, will have high radiative andmore » convective efficiencies and at least a 4:1 turndown ratio. This work presents one such burner which has the potential to meet all of these demands and more. After investigation of a number of burners, including, metal fiber, ported metal, ceramic fiber and ported ceramic, it is believed that cellular ceramic burners will be the best candidates for integration with AMTEC cells for a high power system suitable for hybrid electric vehicles. A detailed study which includes the operating range, radiation efficiency, total heat transfer efficiency, spectral intensity, exit gas temperature and pollutant emission indices measurement has been carried out on circular and square shaped burners. Total heat transfer efficiencies as high as 65--70% have been measured using a water calorimeter. With efficient recuperation, a burner/recuperator efficiency of 80% at peak power and 90% at peak efficiency operating points are conceivable with this burner. Establishment of combustion within the porous matrix leads to low peak temperatures and hence lower NO{sub x}. The emission indices of CO and HC are also quite low. The stability range measurements show a 6:1 turndown ratio at an equivalence ratio of 0.9.« less

Effects of vertically ribbed surface roughness on the forced convective heat losses in central receiver systems

NASA Astrophysics Data System (ADS)

Uhlig, Ralf; Frantz, Cathy; Fritsch, Andreas

2016-05-01

External receiver configurations are directly exposed to ambient wind. Therefore, a precise determination of the convective losses is a key factor in the prediction and evaluation of the efficiency of the solar absorbers. Based on several studies, the forced convective losses of external receivers are modeled using correlations for a roughened cylinder in a cross-flow of air. However at high wind velocities, the thermal efficiency measured during the Solar Two experiment was considerably lower than the efficiency predicted by these correlations. A detailed review of the available literature on the convective losses of external receivers has been made. Three CFD models of different level of detail have been developed to analyze the influence of the actual shape of the receiver and tower configuration, of the receiver shape and of the absorber panels on the forced convective heat transfer coefficients. The heat transfer coefficients deduced from the correlations have been compared to the results of the CFD simulations. In a final step the influence of both modeling approaches on the thermal efficiency of an external tubular receiver has been studied in a thermal FE model of the Solar Two receiver.

Cross-Cultural Differences in Sibling Power Balance and Its Concomitants Across Three Age Periods.

PubMed

Buist, Kirsten L; Metindogan, Aysegül; Coban, Selma; Watve, Sujala; Paranjpe, Analpa; Koot, Hans M; van Lier, Pol; Branje, Susan J T; Meeus, Wim H J

2017-06-01

We examined cross-cultural differences in (1) sibling power balance and (2) the associations between sibling power balance and internalizing and externalizing problems in three separate cross-cultural studies (early childhood, late childhood, and adolescence). The early childhood samples consisted of 123 Turkish and 128 Dutch mothers (mean age for children was 4.9 years). In the late childhood samples, self-report data were collected from 124 Indian and 129 Dutch children (mean age 10.9 years). In the adolescent samples self-report data were collected from 165 ethnic Moroccan and 165 ethnic Dutch adolescents (mean age 15.2 years). In all studies, questionnaire data on sibling power imbalance and internalizing and externalizing problems were collected. Results showed only one significant cross-cultural difference in sibling power imbalance: The Indian sample reported more sibling power imbalance than the Dutch. Links between sibling power imbalance and problem behavior were highly similar between the different cultural samples. The only significant difference was a stronger impact of sibling power imbalance on externalizing problems for the Dutch compared to the Turkish sample. Concluding, few cross-cultural differences were found in sibling power imbalance. Across cultures and age groups, more sibling power imbalance was linked to more internalizing and externalizing problems. © 2017 Wiley Periodicals, Inc.

Novel Programmable Shape Memory Polystyrene Film: A Thermally Induced Beam-power Splitter.

PubMed

Li, Peng; Han, Yu; Wang, Wenxin; Liu, Yanju; Jin, Peng; Leng, Jinsong

2017-03-09

Micro/nanophotonic structures that are capable of optical wave-front shaping are implemented in optical waveguides and passive optical devices to alter the phase of the light propagating through them. The beam division directions and beam power distribution depend on the design of the micro/nanostructures. The ultimate potential of advanced micro/nanophotonic structures is limited by their structurally rigid, functional singleness and not tunable against external impact. Here, we propose a thermally induced optical beam-power splitter concept based on a shape memory polystyrene film with programmable micropatterns. The smooth film exhibits excellent transparency with a transmittance of 95% in the visible spectrum and optical stability during a continuous heating process up to 90 °C. By patterning double sided shape memory polystyrene film into erasable and switchable micro-groove gratings, the transmission light switches from one designed light divided directions and beam-power distribution to another because of the optical diffraction effect of the shape changing micro gratings during the whole thermal activated recovery process. The experimental and theoretical results demonstrate a proof-of-principle of the beam-power splitter. Our results can be adapted to further extend the applications of micro/nanophotonic devices and implement new features in the nanophotonics.

Novel Programmable Shape Memory Polystyrene Film: A Thermally Induced Beam-power Splitter

PubMed Central

Li, Peng; Han, Yu; Wang, Wenxin; Liu, Yanju; Jin, Peng; Leng, Jinsong

2017-01-01

Micro/nanophotonic structures that are capable of optical wave-front shaping are implemented in optical waveguides and passive optical devices to alter the phase of the light propagating through them. The beam division directions and beam power distribution depend on the design of the micro/nanostructures. The ultimate potential of advanced micro/nanophotonic structures is limited by their structurally rigid, functional singleness and not tunable against external impact. Here, we propose a thermally induced optical beam-power splitter concept based on a shape memory polystyrene film with programmable micropatterns. The smooth film exhibits excellent transparency with a transmittance of 95% in the visible spectrum and optical stability during a continuous heating process up to 90 °C. By patterning double sided shape memory polystyrene film into erasable and switchable micro-groove gratings, the transmission light switches from one designed light divided directions and beam-power distribution to another because of the optical diffraction effect of the shape changing micro gratings during the whole thermal activated recovery process. The experimental and theoretical results demonstrate a proof-of-principle of the beam-power splitter. Our results can be adapted to further extend the applications of micro/nanophotonic devices and implement new features in the nanophotonics. PMID:28276500

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

Martinez-Guerra, Edith; Gude, Veera Gnaneswar, E-mail: gude@cee.msstate.edu

Highlights: • Pulse sonication effect on transesterification of waste vegetable oil was studied. • Effects of ethanol, methanol, and alcohol mixtures on FAMEs yield were evaluated. • Effect of ultrasonic intensity, power density, and its output rates were evaluated. • Alcohol mixtures resulted in higher biodiesel yields due to better solubility. - Abstract: This study reports on the effects of direct pulse sonication and the type of alcohol (methanol and ethanol) on the transesterification reaction of waste vegetable oil without any external heating or mechanical mixing. Biodiesel yields and optimum process conditions for the transesterification reaction involving ethanol, methanol, andmore » ethanol–methanol mixtures were evaluated. The effects of ultrasonic power densities (by varying sample volumes), power output rates (in W), and ultrasonic intensities (by varying the reactor size) were studied for transesterification reaction with ethanol, methanol and ethanol–methanol (50%-50%) mixtures. The optimum process conditions for ethanol or methanol based transesterification reaction of waste vegetable oil were determined as: 9:1 alcohol to oil ratio, 1% wt. catalyst amount, 1–2 min reaction time at a power output rate between 75 and 150 W. It was shown that the transesterification reactions using ethanol–methanol mixtures resulted in biodiesel yields as high as >99% at lower power density and ultrasound intensity when compared to ethanol or methanol based transesterification reactions.« less

Novel Programmable Shape Memory Polystyrene Film: A Thermally Induced Beam-power Splitter

NASA Astrophysics Data System (ADS)

Li, Peng; Han, Yu; Wang, Wenxin; Liu, Yanju; Jin, Peng; Leng, Jinsong

2017-03-01

Micro/nanophotonic structures that are capable of optical wave-front shaping are implemented in optical waveguides and passive optical devices to alter the phase of the light propagating through them. The beam division directions and beam power distribution depend on the design of the micro/nanostructures. The ultimate potential of advanced micro/nanophotonic structures is limited by their structurally rigid, functional singleness and not tunable against external impact. Here, we propose a thermally induced optical beam-power splitter concept based on a shape memory polystyrene film with programmable micropatterns. The smooth film exhibits excellent transparency with a transmittance of 95% in the visible spectrum and optical stability during a continuous heating process up to 90 °C. By patterning double sided shape memory polystyrene film into erasable and switchable micro-groove gratings, the transmission light switches from one designed light divided directions and beam-power distribution to another because of the optical diffraction effect of the shape changing micro gratings during the whole thermal activated recovery process. The experimental and theoretical results demonstrate a proof-of-principle of the beam-power splitter. Our results can be adapted to further extend the applications of micro/nanophotonic devices and implement new features in the nanophotonics.

Power generation plant integrating concentrated solar power receiver and pressurized heat exchanger

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

Sakadjian, Bartev B; Flynn, Thomas J; Hu, Shengteng

A power plant includes a solar receiver heating solid particles, a standpipe receiving solid particles from the solar receiver, a pressurized heat exchanger heating working fluid by heat transfer through direct contact with heated solid particles flowing out of the bottom of the standpipe, and a flow path for solid particles from the bottom of the standpipe into the pressurized heat exchanger that is sealed by a pressure P produced at the bottom of the standpipe by a column of heated solid particles of height H. The flow path may include a silo or surge tank comprising a pressure vesselmore » connected to the bottom of the standpipe, and a non-mechanical valve. The power plant may further include a turbine driven by heated working fluid discharged from the pressurized heat exchanger, and a compressor driven by the turbine.« less

A model for allometric scaling of mammalian metabolism with ambient heat loss.

PubMed

Kwak, Ho Sang; Im, Hong G; Shim, Eun Bo

2016-03-01

Allometric scaling, which represents the dependence of biological traits or processes on body size, is a long-standing subject in biological science. However, there has been no study to consider heat loss to the ambient and an insulation layer representing mammalian skin and fur for the derivation of the scaling law of metabolism. A simple heat transfer model is proposed to analyze the allometry of mammalian metabolism. The present model extends existing studies by incorporating various external heat transfer parameters and additional insulation layers. The model equations were solved numerically and by an analytic heat balance approach. A general observation is that the present heat transfer model predicted the 2/3 surface scaling law, which is primarily attributed to the dependence of the surface area on the body mass. External heat transfer effects introduced deviations in the scaling law, mainly due to natural convection heat transfer, which becomes more prominent at smaller mass. These deviations resulted in a slight modification of the scaling exponent to a value < 2/3. The finding that additional radiative heat loss and the consideration of an outer insulation fur layer attenuate these deviation effects and render the scaling law closer to 2/3 provides in silico evidence for a functional impact of heat transfer mode on the allometric scaling law in mammalian metabolism.

Time-dependent photon heat transport through a mesoscopic Josephson device

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

Lu, Wen-Ting; Zhao, Hong-Kang, E-mail: zhaohonk@bit.edu.cn

The time-oscillating photon heat current through a dc voltage biased mesoscopic Josephson Junction (MJJ) has been investigated by employing the nonequilibrium Green’s function approach. The Landauer-like formula of photon heat current has been derived in both of the Fourier space and its time-oscillating versions, where Coulomb interaction, self inductance, and magnetic flux take effective roles. Nonlinear behaviors are exhibited in the photon heat current due to the quantum nature of MJJ and applied external dc voltage. The magnitude of heat current decreases with increasing the external bias voltage, and subtle oscillation structures appear as the superposition of different photon heatmore » branches. The overall period of heat current with respect to time is not affected by Coulomb interaction, however, the magnitude and phase of it vary considerably by changing the Coulomb interaction. - Highlights: • The time-oscillating photon heat current through a mesoscopic Josephson Junction has been investigated. • The Landauer-like formula of photon heat current has been derived by the nonequilibrium Green’s function approach. • Nonlinear behaviors are exhibited in the photon heat current resulting from the self inductance and Coulomb interaction. • The oscillation structure of heat current is composed of the superposition of oscillations with different periods.« less

High-power quantum-dot tapered tunable external-cavity lasers based on chirped and unchirped structures.

PubMed

Haggett, Stephanie; Krakowski, Michel; Montrosset, Ivo; Cataluna, Maria Ana

2014-09-22

A high-power tunable external cavity laser configuration with a tapered quantum-dot semiconductor optical amplifier at its core is presented, enabling a record output power for a broadly tunable semiconductor laser source in the 1.2 - 1.3 µm spectral region. Two distinct optical amplifiers are investigated, using either chirped or unchirped quantum-dot structures, and their merits are compared, considering the combination of tunability and high output power generation. At 1230 nm, the chirped quantum-dot laser achieved a maximum power of 0.62 W and demonstrated nearly 100-nm tunability. The unchirped laser enabled a tunability range of 32 nm and at 1254 nm generated a maximum power of 0.97 W, representing a 22-fold increase in output power compared with similar narrow-ridge external-cavity lasers at the same current density.

Passive cooling system for a vehicle

DOEpatents

Hendricks, Terry Joseph; Thoensen, Thomas

2005-11-15

A passive cooling system for a vehicle (114) transfers heat from an overheated internal component, for example, an instrument panel (100), to an external portion (116) of the vehicle (114), for example, a side body panel (126). The passive cooling system includes one or more heat pipes (112) having an evaporator section (118) embedded in the overheated internal component and a condenser section (120) at the external portion (116) of the vehicle (114). The evaporator (118) and condenser (120) sections are in fluid communication. The passive cooling system may also include a thermally conductive film (140) for thermally connecting the evaporator sections (118) of the heat pipes (112) to each other and to the instrument panel (100).

Passive Cooling System for a Vehicle

DOEpatents

Hendricks, T. J.; Thoensen, T.

2005-11-15

A passive cooling system for a vehicle (114) transfers heat from an overheated internal component, for example, an instrument panel (100), to an external portion (116) of the vehicle (114), for example, a side body panel (126). The passive cooling system includes one or more heat pipes (112) having an evaporator section (118) embedded in the overheated internal component and a condenser section (120) at the external portion (116) of the vehicle (114). The evaporator (118) and condenser (120) sections are in fluid communication. The passive cooling system may also include a thermally conductive film (140) for thermally connecting the evaporator sections (118) of the heat pipes (112) to each other and to the instrument panel (100).

Pressure and heat flux results from the space shuttle/external fuel tank interaction test at Mach numbers 16 and 19

NASA Technical Reports Server (NTRS)

Brewer, E. B.; Haberman, D. R.

1974-01-01

Heat transfer rates and pressures were measured on a 0.0175-scale model of the space shuttle external tank (ET), model MCR0200. Tests were conducted with the ET model separately and while mated with a 0.0175-scale model of the orbiter, model 21-OT (Grumman). The tests were conducted in the AEDC-VKF Hypervelocity Wind Tunnel (F) at Mach numbers 16 and 19. The primary data consisted of the interaction heating rates experienced by the ET while mated with the orbiter in the flight configuration. Data were taken for a range of Reynolds numbers from 50,000 to 65,000 under laminar flow conditions.

The Importance of Physical Models for Deriving Dust Masses and Grain Size Distributions in Supernova Ejecta. I. Radiatively Heated Dust in the Crab Nebula

NASA Technical Reports Server (NTRS)

Temim, Tea; Dwek, Eli

2013-01-01

Recent far-infrared (IR) observations of supernova remnants (SNRs) have revealed significantly large amounts of newly condensed dust in their ejecta, comparable to the total mass of available refractory elements. The dust masses derived from these observations assume that all the grains of a given species radiate at the same temperature, regardless of the dust heating mechanism or grain radius. In this paper, we derive the dust mass in the ejecta of the Crab Nebula, using a physical model for the heating and radiation from the dust. We adopt a power-law distribution of grain sizes and two different dust compositions (silicates and amorphous carbon), and calculate the heating rate of each dust grain by the radiation from the pulsar wind nebula. We find that the grains attain a continuous range of temperatures, depending on their size and composition. The total mass derived from the best-fit models to the observed IR spectrum is 0.019-0.13 Solar Mass, depending on the assumed grain composition. We find that the power-law size distribution of dust grains is characterized by a power-law index of 3.5-4.0 and a maximum grain size larger than 0.1 micron. The grain sizes and composition are consistent with what is expected for dust grains formed in a Type IIP supernova (SN). Our derived dust mass is at least a factor of two less than the mass reported in previous studies of the Crab Nebula that assumed more simplified two-temperature models. These models also require a larger mass of refractory elements to be locked up in dust than was likely available in the ejecta. The results of this study show that a physical model resulting in a realistic distribution of dust temperatures can constrain the dust properties and affect the derived dust masses. Our study may also have important implications for deriving grain properties and mass estimates in other SNRs and for the ultimate question of whether SNe are major sources of dust in the Galactic interstellar medium and in external galaxies.

Heat-machine control by quantum-state preparation: from quantum engines to refrigerators.

PubMed

Gelbwaser-Klimovsky, D; Kurizki, G

2014-08-01

We explore the dependence of the performance bounds of heat engines and refrigerators on the initial quantum state and the subsequent evolution of their piston, modeled by a quantized harmonic oscillator. Our goal is to provide a fully quantized treatment of self-contained (autonomous) heat machines, as opposed to their prevailing semiclassical description that consists of a quantum system alternately coupled to a hot or a cold heat bath and parametrically driven by a classical time-dependent piston or field. Here, by contrast, there is no external time-dependent driving. Instead, the evolution is caused by the stationary simultaneous interaction of two heat baths (having distinct spectra and temperatures) with a single two-level system that is in turn coupled to the quantum piston. The fully quantized treatment we put forward allows us to investigate work extraction and refrigeration by the tools of quantum-optical amplifier and dissipation theory, particularly, by the analysis of amplified or dissipated phase-plane quasiprobability distributions. Our main insight is that quantum states may be thermodynamic resources and can provide a powerful handle, or control, on the efficiency of the heat machine. In particular, a piston initialized in a coherent state can cause the engine to produce work at an efficiency above the Carnot bound in the linear amplification regime. In the refrigeration regime, the coefficient of performance can transgress the Carnot bound if the piston is initialized in a Fock state. The piston may be realized by a vibrational mode, as in nanomechanical setups, or an electromagnetic field mode, as in cavity-based scenarios.

Heat-machine control by quantum-state preparation: From quantum engines to refrigerators

NASA Astrophysics Data System (ADS)

Gelbwaser-Klimovsky, D.; Kurizki, G.

2014-08-01

We explore the dependence of the performance bounds of heat engines and refrigerators on the initial quantum state and the subsequent evolution of their piston, modeled by a quantized harmonic oscillator. Our goal is to provide a fully quantized treatment of self-contained (autonomous) heat machines, as opposed to their prevailing semiclassical description that consists of a quantum system alternately coupled to a hot or a cold heat bath and parametrically driven by a classical time-dependent piston or field. Here, by contrast, there is no external time-dependent driving. Instead, the evolution is caused by the stationary simultaneous interaction of two heat baths (having distinct spectra and temperatures) with a single two-level system that is in turn coupled to the quantum piston. The fully quantized treatment we put forward allows us to investigate work extraction and refrigeration by the tools of quantum-optical amplifier and dissipation theory, particularly, by the analysis of amplified or dissipated phase-plane quasiprobability distributions. Our main insight is that quantum states may be thermodynamic resources and can provide a powerful handle, or control, on the efficiency of the heat machine. In particular, a piston initialized in a coherent state can cause the engine to produce work at an efficiency above the Carnot bound in the linear amplification regime. In the refrigeration regime, the coefficient of performance can transgress the Carnot bound if the piston is initialized in a Fock state. The piston may be realized by a vibrational mode, as in nanomechanical setups, or an electromagnetic field mode, as in cavity-based scenarios.

Modeling assisted evaluation of direct electricity generation from waste heat of wastewater via a thermoelectric generator.

PubMed

Zou, Shiqiang; Kanimba, Eurydice; Diller, Thomas E; Tian, Zhiting; He, Zhen

2018-04-22

The thermal energy represents a significant portion of energy potential in municipal wastewater and may be recovered as electricity by a thermoelectric generator (TEG). Converting heat to all-purpose electricity by TEG has been demonstrated with large heat gradients, but its application in waste heat recovery from wastewater has not been well evaluated. Herein, a bench-scale Bi 2 Te 3 -based waste heat recovery system was employed to generate electricity from a low temperature gradient through a combination of experiments and mathematical modeling. With an external resistance of 7.8 Ω and a water (hot side) flow rate of 75 mL min -1 , a maximum normalized energy recovery of 4.5 × 10 -4  kWh m -3 was achieved under a 2.8 °C temperature gradient (ΔT). Model simulation indicated a boost in both power output and energy conversion efficiency from 0.76 mW and 0.13% at ΔT = 2.8 °C to 61.83 mW and 1.15% at ΔT = 25 °C. Based on the data of two-year water/air temperature obtained from the Christiansburg Wastewater Treatment Plant, an estimated energy generation of 1094 to 70,986 kWh could be expected annually with a saving of $163 to $6076. Those results have revealed a potential for TEG-centered direct electricity generation from low-grade heat towards enhanced resource recovery from wastewater and encouraged further exploration of this approach. Copyright © 2018. Published by Elsevier B.V.

A comparison of radioisotope Brayton and Stirling system for lunar surface mobile power

NASA Astrophysics Data System (ADS)

Harty, Richard B.

1991-01-01

A study was performed by the Rocketdyne Division of Rockwell 2.5-kWe modular dynamic isotope power system (DIPS) using a Stirling power conversion system. The results of this study were compared with similar results performed under the DIPS program using a Brayton power conversion system. The study indicated that the Stirling power module has 20% lower mass and 40% lower radiator area than the Brayton module. However, the study also revealed that because the Stirling power module requires a complex heat pipe arrangment to transport heat from the isotope to the Stirling heater head and a pumped NaK heat rejection loop, the Stirling module is much more difficult to integrate with the isotope heat source and heat rejection system.

Passive rejection of heat from an isotope heat source through an open door

NASA Technical Reports Server (NTRS)

Burns, R. K.

1971-01-01

The isotope heat-source design for a Brayton power system includes a door in the thermal insulation through which the heat can be passively rejected to space when the power system is not operating. The results of an analysis to predict the heat-source surface temperature and the heat-source heat-exchanger temperature during passive heat rejection as a function of insulation door opening angle are presented. They show that for a door opening angle greater than 20 deg, the temperatures are less than the steady-state temperatures during power system operation.

46 CFR 129.550 - Power for cooking and heating.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Power for cooking and heating. 129.550 Section 129.550... INSTALLATIONS Miscellaneous Electrical Systems § 129.550 Power for cooking and heating. (a) Equipment for cooking and heating must be suitable for marine use. Equipment designed and installed to comply with ABYC...

Analysis of classical Fourier, SPL and DPL heat transfer model in biological tissues in presence of metabolic and external heat source

NASA Astrophysics Data System (ADS)

Kumar, Dinesh; Singh, Surjan; Rai, K. N.

2016-06-01

In this paper, the temperature distribution in a finite biological tissue in presence of metabolic and external heat source when the surface subjected to different type of boundary conditions is studied. Classical Fourier, single-phase-lag (SPL) and dual-phase-lag (DPL) models were developed for bio-heat transfer in biological tissues. The analytical solution obtained for all the three models using Laplace transform technique and results are compared. The effect of the variability of different parameters such as relaxation time, metabolic heat source, spatial heat source, different type boundary conditions on temperature distribution in different type of the tissues like muscle, tumor, fat, dermis and subcutaneous based on three models are analyzed and discussed in detail. The result obtained in three models is compared with experimental observation of Stolwijk and Hardy (Pflug Arch 291:129-162, 1966). It has been observe that the DPL bio-heat transfer model provides better result in comparison of other two models. The value of metabolic and spatial heat source in boundary condition of first, second and third kind for different type of thermal therapies are evaluated.

Computational Model of Heat Transfer on the ISS

NASA Technical Reports Server (NTRS)

Torian, John G.; Rischar, Michael L.

2008-01-01

SCRAM Lite (SCRAM signifies Station Compact Radiator Analysis Model) is a computer program for analyzing convective and radiative heat-transfer and heat-rejection performance of coolant loops and radiators, respectively, in the active thermal-control systems of the International Space Station (ISS). SCRAM Lite is a derivative of prior versions of SCRAM but is more robust. SCRAM Lite computes thermal operating characteristics of active heat-transport and heat-rejection subsystems for the major ISS configurations from Flight 5A through completion of assembly. The program performs integrated analysis of both internal and external coolant loops of the various ISS modules and of an external active thermal control system, which includes radiators and the coolant loops that transfer heat to the radiators. The SCRAM Lite run time is of the order of one minute per day of mission time. The overall objective of the SCRAM Lite simulation is to process input profiles of equipment-rack, crew-metabolic, and other heat loads to determine flow rates, coolant supply temperatures, and available radiator heat-rejection capabilities. Analyses are performed for timelines of activities, orbital parameters, and attitudes for mission times ranging from a few hours to several months.

Aerodynamic heating to representative SRB and ET protuberances

NASA Technical Reports Server (NTRS)

Engel, C. D.; Lapointe, J. K.

1979-01-01

Heating data and data scaling methods which can be used on representative solid rocket booster and external tank (ET) protuberances are described. Topics covered include (1) ET geometry and heating points; (2) interference heating test data (51A); (3) heat transfer data from tests FH-15 and FH-16; (4) individual protuberance data; and (5) interference heating of paint data from test IH-42. A set of drawings of the ET moldline and protuberances is included.

A comparison of radioisotope Brayton and Stirling systems for lunar surface mobile power

NASA Astrophysics Data System (ADS)

Harty, Richard B.

A study was performed by the Rocketdyne Division of Rockwell International on a 2.5-kWe modular dynamic isotope power system (DIPS) using a Stirling power conversion system. The results of this study were compared with similar results performed under the DIPS program using a Brayton power conversion system. The application considered was for lunar mobile power sources in the power range of 2.5 kWe to 15 kWe. The study indicated that the Stirling power module has 20 percent lower mass and 40 percent lower radiator area than the Brayton module. However, the study also revealed that because the Stirling power module requires a complex heat pipe arrangement to transport heat from the isotope to the Stirling heater head and a pumped NaK heat rejection loop, the Stirling module is much more difficult to integrate with the isotope heat source and heat rejection system.

The status of Fast Ignition Realization Experiment (FIREX) and prospects for inertial fusion energy

NASA Astrophysics Data System (ADS)

Azechi, H.; FIREX Project Team

2016-05-01

Here we report recent progress for the fast ignition inertial confinement fusion demonstration. The fraction of low energy (< 1 MeV) component of the relativistic electron beam (REB), which efficiently heats the fuel core, increases by a factor of 4 by enhancing pulse contrast of heating laser and removing preformed plasma sources. Kilo-tesla magnetic field is studied to guide the diverging REB to the fuel core. The transport simulation of the REB accelerated by the heating laser in the externally applied and compressed magnetic field indicates that the REB can be guided efficiently to the fuel core. The integrated simulation shows > 4% of the heating efficiency and > 4 keV of ion temperature are achievable by using GEKKO-XII and LFEX, properly designed cone-fuel and an external magnetic field.

Work production of quantum rotor engines

NASA Astrophysics Data System (ADS)

Seah, Stella; Nimmrichter, Stefan; Scarani, Valerio

2018-04-01

We study the mechanical performance of quantum rotor heat engines in terms of common notions of work using two prototypical models: a mill driven by the heat flow from a hot to a cold mode, and a piston driven by the alternate heating and cooling of a single working mode. We evaluate the extractable work in terms of ergotropy, the kinetic energy associated to net directed rotation, as well as the intrinsic work based on the exerted torque under autonomous operation, and we compare them to the energy output for the case of an external dissipative load and for externally driven engine cycles. Our results connect work definitions from both physical and information-theoretical perspectives. In particular, we find that apart from signatures of angular momentum quantization, the ergotropy is consistent with the intuitive notion of work in the form of net directed motion. It also agrees with the energy output to an external load or agent under optimal conditions. This sets forth a consistent thermodynamical description of rotating quantum motors, flywheels, and clocks.

Design of a nuclear isotope heat source assembly for a spaceborne mini-Brayton power module.

NASA Technical Reports Server (NTRS)

Wein, D.; Gorland, S. H.

1973-01-01

Results of a study to develop a feasible design definition of a heat source assembly (HSA) for use in nominal 500-, 1200-, or 2000-W(e) mini-Brayton spacecraft power systems. The HSA is a modular design which is used either as a single unit to provide thermal energy to the 500-W(e) mini-Brayton power module or in parallel with one or two additional HSAs for the 1200- or 2000-W(e) power module systems. Principal components consist of a multihundred watt RTG isotope heat source, a heat source heat exchanger which transfers the thermal energy from the heat source to the mini-Brayton power conversion system, an auxiliary cooling system which provides requisite cooling during nonoperation of the power conversion module and an emergency cooling system which precludes accidental release of isotope fuel in the event of system failure.

Lateral Load Testing of the Advanced Stirling Convertor (ASC-E2) Heater Head

NASA Technical Reports Server (NTRS)

Cornell, Peggy A.; Krause, David L.; Davis, Glen; Robbie, Malcolm G.; Gubics, David A.

2010-01-01

Free-piston Stirling convertors are fundamental to the development of NASA s next generation of radioisotope power system, the Advanced Stirling Radioisotope Generator (ASRG). The ASRG will use General Purpose Heat Source (GPHS) modules as the energy source and Advanced Stirling Convertors (ASCs) to convert heat into electrical energy, and is being developed by Lockheed Martin under contract to the Department of Energy. Achieving flight status mandates that the ASCs satisfy design as well as flight requirements to ensure reliable operation during launch. To meet these launch requirements, GRC performed a series of quasi-static mechanical tests simulating the pressure, thermal, and external loading conditions that will be experienced by an ASC-E2 heater head assembly. These mechanical tests were collectively referred to as "lateral load tests" since a primary external load lateral to the heater head longitudinal axis was applied in combination with the other loading conditions. The heater head was subjected to the operational pressure, axial mounting force, thermal conditions, and axial and lateral launch vehicle acceleration loadings. To permit reliable prediction of the heater head s structural performance, GRC completed Finite Element Analysis (FEA) computer modeling for the stress, strain, and deformation that will result during launch. The heater head lateral load test directly supported evaluation of the analysis and validation of the design to meet launch requirements. This paper provides an overview of each element within the test and presents assessment of the modeling as well as experimental results of this task.

Lateral Load Testing of the Advanced Stirling Convertor (ASC-E2) Heater Head

NASA Technical Reports Server (NTRS)

Cornell, Peggy A.; Krause, David L.; Davis, Glen; Robbie, Malcolm G.; Gubics, David A.

2011-01-01

Free-piston Stirling convertors are fundamental to the development of NASA s next generation of radioisotope power system, the Advanced Stirling Radioisotope Generator (ASRG). The ASRG will use General Purpose Heat Source (GPHS) modules as the energy source and Advanced Stirling Convertors (ASCs) to convert heat into electrical energy, and is being developed by Lockheed Martin under contract to the Department of Energy. Achieving flight status mandates that the ASCs satisfy design as well as flight requirements to ensure reliable operation during launch. To meet these launch requirements, GRC performed a series of quasi-static mechanical tests simulating the pressure, thermal, and external loading conditions that will be experienced by an ASC-E2 heater head assembly. These mechanical tests were collectively referred to as "lateral load tests" since a primary external load lateral to the heater head longitudinal axis was applied in combination with the other loading conditions. The heater head was subjected to the operational pressure, axial mounting force, thermal conditions, and axial and lateral launch vehicle acceleration loadings. To permit reliable prediction of the heater head s structural performance, GRC completed Finite Element Analysis (FEA) computer modeling for the stress, strain, and deformation that will result during launch. The heater head lateral load test directly supported evaluation of the analysis and validation of the design to meet launch requirements. This paper provides an overview of each element within the test and presents assessment of the modeling as well as experimental results of this task.

Lateral Load Testing of the Advanced Stirling Convertor (ASC-E2) Heater Head

NASA Technical Reports Server (NTRS)

Cornell, Peggy A.; Krause, David L.; Davis, Glen; Robbie, Malcolm G.; Gubics, David A.

2010-01-01

Free-piston Stirling convertors are fundamental to the development of NASA s next generation of radioisotope power system, the Advanced Stirling Radioisotope Generator (ASRG). The ASRG will use General Purpose Heat Source (GPHS) modules as the energy source and Advanced Stirling Convertors (ASCs) to convert heat into electrical energy, and is being developed by Lockheed Martin under contract to the Department of Energy. Achieving flight status mandates that the ASCs satisfy design as well as flight requirements to ensure reliable operation during launch. To meet these launch requirements, GRC performed a series of quasi-static mechanical tests simulating the pressure, thermal, and external loading conditions that will be experienced by an ASC E2 heater head assembly. These mechanical tests were collectively referred to as lateral load tests since a primary external load lateral to the heater head longitudinal axis was applied in combination with the other loading conditions. The heater head was subjected to the operational pressure, axial mounting force, thermal conditions, and axial and lateral launch vehicle acceleration loadings. To permit reliable prediction of the heater head s structural performance, GRC completed Finite Element Analysis (FEA) computer modeling for the stress, strain, and deformation that will result during launch. The heater head lateral load test directly supported evaluation of the analysis and validation of the design to meet launch requirements. This paper provides an overview of each element within the test and presents assessment of the modeling as well as experimental results of this task.

Emergency heat removal system for a nuclear reactor

DOEpatents

Dunckel, Thomas L.

1976-01-01

A heat removal system for nuclear reactors serving as a supplement to an Emergency Core Cooling System (ECCS) during a Loss of Coolant Accident (LOCA) comprises a plurality of heat pipes having one end in heat transfer relationship with either the reactor pressure vessel, the core support grid structure or other in-core components and the opposite end located in heat transfer relationship with a heat exchanger having heat transfer fluid therein. The heat exchanger is located external to the pressure vessel whereby excessive core heat is transferred from the above reactor components and dissipated within the heat exchanger fluid.

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.

Control system for, and a method of, heating an operator station of a work machine

DOEpatents

Baker, Thomas M.; Hoff, Brian D.; Akasam, Sivaprasad

2005-04-05

There are situations in which an operator remains in an operator station of a work machine when an engine of the work machine is inactive. The present invention includes a control system for, and a method of, heating the operator station when the engine is inactive. A heating system of the work machine includes an electrically-powered coolant pump, a power source, and at least one piece of warmed machinery. An operator heat controller is moveable between a first and a second position, and is operable to connect the electrically-powered coolant pump to the power source when the engine is inactive and the operator heat controller is in the first position. Thus, by deactivating the engine and then moving the operator heat controller to the first position, the operator may supply electrical energy to the electrically-powered coolant pump, which is operably coupled to heat the operator station.