Science.gov

Sample records for air side heat

  1. Air-side flow and heat transfer in compact heat exchangers: A discussion of enhancement mechanisms

    SciTech Connect

    Jacobi, A.M.; Shah, R.K.

    1998-10-01

    The behavior of air flows in complex heat exchanger passages is reviewed with a focus on the heat transfer effects of boundary-layer development, turbulence, spanwise and streamwise vortices, and wake management. Each of these flow features is discussed for the plain, wavy, and interrupted passages found in contemporary compact heat exchanger designs. Results from the literature are used to help explain the role of these mechanisms in heat transfer enhancement strategies.

  2. Air side thermal performance of wavy fin heat exchangers produced by selective laser melting

    NASA Astrophysics Data System (ADS)

    Kuehndel, J.; Kerler, B.; Karcher, C.

    2016-09-01

    Wavy fins are widely used for off-road vehicle coolers, due to their dust resistance. In this study, heat exchanger elements with wavy fins were examined in an experimental study. Due to independence of tooling and degrees of freedom in design, rapid prototyping technique selective laser melting was used to produce heat exchanger elements with high dimensional accuracy. Tests were conducted for air side Reynolds number Re of 1400-7400 varying wavy amplitude and wave length at a constant water flow rate of 9.0m3/h inside the tubes. The effects of wavy amplitude and wave length on the air side thermal performance were studied. Experimental correlation equations for Nu and ­ were derived by regression analysis.

  3. A Novel Approach to Model the Air-Side Heat Transfer in Microchannel Condensers

    NASA Astrophysics Data System (ADS)

    Martínez-Ballester, S.; Corberán, José-M.; Gonzálvez-Maciá, J.

    2012-11-01

    The work presents a model (Fin1D×3) for microchannel condensers and gas coolers. The paper focusses on the description of the novel approach employed to model the air-side heat transfer. The model applies a segment-by-segment discretization to the heat exchanger adding, in each segment, a specific bi-dimensional grid to the air flow and fin wall. Given this discretization, the fin theory is applied by using a continuous piecewise function for the fin wall temperature. It allows taking into account implicitly the heat conduction between tubes along the fin, and the unmixed air influence on the heat capacity. The model has been validated against experimental data resulting in predicted capacity errors within ± 5%. Differences on prediction results and computational cost were studied and compared with the previous authors' model (Fin2D) and with other simplified model. Simulation time of the proposed model was reduced one order of magnitude respect the Fin2D's time retaining its same accuracy.

  4. A correlation to predict the heat flux on the air-side of a vapor chamber with overturn-U flattened tubes

    NASA Astrophysics Data System (ADS)

    Srimuang, Wasan; Limkaisang, Viroj

    2016-08-01

    The heat transfer characteristics of a conventional vapor chamber (CVC) and a loop vapor chamber (LVC) are compared. The vapor chambers consisted of a stainless steel box with different covers. The results indicated that the heat flux and convective heat transfer coefficient of the air-side of LVC is higher than CVC. An empirical correlation was developed to predict the convective heat transfer coefficient of the air-side of the LVC.

  5. Experimental and numerical investigation on air-side performance of fin-and-tube heat exchangers with various fin patterns

    SciTech Connect

    Tang, L.H.; Zeng, M.; Wang, Q.W.

    2009-07-15

    Air-side heat transfer and friction characteristics of five kinds of fin-and-tube heat exchangers, with the number of tube rows (N = 12) and the diameter of tubes (D{sub o} = 18 mm), have been experimentally investigated. The test samples consist of five types of fin configurations: crimped spiral fin, plain fin, slit fin, fin with delta-wing longitudinal vortex generators (VGs) and mixed fin with front 6-row vortex-generator fin and rear 6-row slit fin. The heat transfer and friction factor correlations for different types of heat exchangers were obtained with the Reynolds numbers ranging from 4000 to 10000. It was found that crimped spiral fin provides higher heat transfer and pressure drop than the other four fins. The air-side performance of heat exchangers with the above five fins has been evaluated under three sets of criteria and it was shown that the heat exchanger with mixed fin (front vortex-generator fin and rear slit fin) has better performance than that with fin with delta-wing vortex generators, and the slit fin offers best heat transfer performance at high Reynolds numbers. Based on the correlations of numerical data, Genetic Algorithm optimization was carried out, and the optimization results indicated that the increase of VG attack angle or length, or decrease of VG height may enhance the performance of vortex-generator fin. The heat transfer performances for optimized vortex-generator fin and slit fin at hand have been compared with numerical method. (author)

  6. Finned tube heat exchangers: state of the art for the air side

    SciTech Connect

    McQuiston, F. C.

    1980-01-01

    The findings of various investigators during the past ten years has greatly enhanced our ability to analyze, model, design, and optimize the finned tube heat exchangers so widely used in the HVAC business. The effect of rows, fin pitch, and other geometric parameters are now well understood and generalized heat transfer correlations are available. The relation between heat and mass transfer has been much better defined and good correlations have been developed. Some advances have also been made in modeling techniques especially where partially dry cooling and dehumidifying coils are involved. All of these factors are reviewed to concisely summarize what is now available to the heat exchanger analyst.

  7. Air heating system

    DOEpatents

    Primeau, John J.

    1983-03-01

    A self-starting, fuel-fired, air heating system including a vapor generator, a turbine, and a condenser connected in a closed circuit such that the vapor output from the vapor generator is conducted to the turbine and then to the condenser where it is condensed for return to the vapor generator. The turbine drives an air blower which passes air over the condenser for cooling the condenser. Also, a condensate pump is driven by the turbine. The disclosure is particularly concerned with the provision of heat exchanger and circuitry for cooling the condensed fluid output from the pump prior to its return to the vapor generator.

  8. Turbine airfoil gas side heat transfer

    NASA Technical Reports Server (NTRS)

    Turner, E. R.

    1984-01-01

    Work is currently underway to develop and characterize an analytical approach, based on boundary layer theory, for predicting the effects of leading edge (showerhead) film cooling on downstream gas side heat transfer rates. Parallel to this work, experiments are being conducted to build a relevant data base for present and future methods verification.

  9. Thermodynamic analysis and optimization of air-cooled heat exchangers

    NASA Astrophysics Data System (ADS)

    Salimpour, Mohammad Reza; Bahrami, Zabihollah

    2011-01-01

    In the present study, a thermodynamic second-law analysis was performed to investigate the effects of different geometry and flow parameters on the air-cooled heat exchanger performance. For this purpose, the entropy generation due to heat transfer and pressure loss of internal and external flows of the air-cooled heat exchanger was calculated; and it was observed that the total entropy generation has a minimum at special tube-side Reynolds number. Also, it was seen that the increasing of the tube-side Reynolds number resulted in the rise of the irreversibility of the air-cooled heat exchanger. The results also showed when air-side Reynolds number decreased, the entropy generation rate of the external flow reduced. Finally, based on the computed results, a new correlation was developed to predict the optimum Reynolds number of the tube-side fluid flow.

  10. SOUTHEAST AND NORTHEAST SIDES. Looking west Edwards Air Force ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    SOUTHEAST AND NORTHEAST SIDES. Looking west - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Fuel & Water Tank, Test Area 1-115, northwest end of Saturn Boulevard, Boron, Kern County, CA

  11. SOUTH FRONT AND EAST SIDE. January, 1998 Edwards Air ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    SOUTH FRONT AND EAST SIDE. January, 1998 - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Electrical Substation, Test Area 1-115, northwest end of Saturn Boulevard, Boron, Kern County, CA

  12. Efficacy of side air bags in reducing driver deaths in driver-side collisions.

    PubMed

    Braver, Elisa R; Kyrychenko, Sergey Y

    2004-03-15

    Side air bags, a relatively new technology designed to protect the head and/or torso in side-impact collisions, are becoming increasingly common in automobiles. Their efficacy in preventing US driver deaths among cars struck on the near (driver's) side was examined using data from the Fatality Analysis Reporting System and the General Estimates System. Risk ratios for driver death per nearside collision during 1999-2001 were computed for head/torso and torso-only side air bags in cars from model years 1997-2002, relative to cars without side air bags. Confounding was addressed by adjusting nearside risk ratios for front- and rear-impact mortality, which is unaffected by side air bags. Risk ratios were 0.55 (95% confidence interval: 0.43, 0.71) for head/torso air bags and 0.89 (95% confidence interval: 0.79, 1.01) for torso-only air bags. Risk was reduced when cars with head/torso air bags were struck by cars/minivans (significant) or pickup trucks/sport utility vehicles (nonsignificant). Risk was reduced in two-vehicle collisions and among male drivers and drivers aged 16-64 years. Protective effects associated with torso-only air bags were observed in single-vehicle crashes and among male and 16- to 64-year-old drivers. Head/torso side air bags appear to be very effective in reducing nearside driver deaths, whereas torso-only air bags appear less protective.

  13. 15. BASE OF MST, SOUTHEAST SIDE, FACING SOUTHWEST. AIR COMPRESSOR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. BASE OF MST, SOUTHEAST SIDE, FACING SOUTHWEST. AIR COMPRESSOR SHED AT STATION 3; PLATFORM AT STATION 12; ENVIRONMENTAL CURTAIN SWING AT STATION 21. ELECTRICAL HOOKUPS ON RIGHT SIDE OF PHOTOGRAPH. - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 East, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  14. Simulation model air-to-air plate heat exchanger

    SciTech Connect

    Wetter, Michael

    1999-01-01

    A simple simulation model of an air-to-air plate heat exchanger is presented. The model belongs to a collection of simulation models that allows the eflcient computer simulation of heating, ventilation, and air-conditioning (HVAC) systems. The main emphasis of the models is to shorten computation time and to use only input data that are known in the design process of an HVAC system. The target of the models is to describe the behavior of HVAC components in the part-load operation mode, which is becoming increasingly important in energy eficient HVAC systems. The models are intended to be used for yearly energy calculations or load calculations with time steps of about 10 minutes or larger. Short- time dynamic effects, which are of interest for different aspects of control theory, are neglected. The part-load behavior is expressed in terms of the nominal condition and the dimensionless variation of the heat transfer with change of mass flow and temperature. The effectiveness- NTU relations are used to parametrize the convective heat transfer at nominal conditions and to compute the part-load condition. If the heat transfer coefficients on the two exchanger sides are not equal (i. e. due to partial bypassing of air), their ratio can be easily calculated and set as a parameter. The model is static and uses explicit equations only. The explicit model formulation ensures short computation time and numerical stability, which allows using the model with sophisticated engineering methods like automatic system optimization. This paper fully outlines the algorithm description and its simplifications. It is not tailored for any particular simulation program to ensure easy implementation in any simulation program.

  15. 6. Missile Alert Facility, west side. Thalheimer Whiteman Air ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. Missile Alert Facility, west side. Thalheimer - Whiteman Air Force Base, Oscar O-1 Minuteman Missile Alert Facility, Southeast corner of Twelfth & Vendenberg Avenues, Knob Noster, Johnson County, MO

  16. NORTHWEST FRONT AND SOUTHWEST SIDE, BUILDING 1933 Edwards Air ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    NORTHWEST FRONT AND SOUTHWEST SIDE, BUILDING 1933 - Edwards Air Force Base, X-15 Engine Test Complex, Observation Bunker Types, Rogers Dry Lake, east of runway between North Base & South Base, Boron, Kern County, CA

  17. 3. SOUTH SIDE. Edwards Air Force Base, South Base ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. SOUTH SIDE. - Edwards Air Force Base, South Base Sled Track, Firing & Control Blockhouse for 10,000-foot Track, South of Sled Track at midpoint of 20,000-foot track, Lancaster, Los Angeles County, CA

  18. 5. NORTH SIDE AND WEST REAR. Edwards Air Force ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. NORTH SIDE AND WEST REAR. - Edwards Air Force Base, South Base Sled Track, Firing & Control Blockhouse for 10,000-foot Track, South of Sled Track at midpoint of 20,000-foot track, Lancaster, Los Angeles County, CA

  19. Heat Recovery Ventilation for Housing: Air-to-Air Heat Exchangers.

    ERIC Educational Resources Information Center

    Corbett, Robert J.; Miller, Barbara

    The air-to-air heat exchanger (a fan powered ventilation device that recovers heat from stale outgoing air) is explained in this six-part publication. Topic areas addressed are: (1) the nature of air-to-air heat exchangers and how they work; (2) choosing and sizing the system; (3) installation, control, and maintenance of the system; (4) heat…

  20. 28. Main engine air pump located to port side of ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    28. Main engine air pump located to port side of main engine cylinder beside engine bed. Dynamo lies aft of air pump (at right), pipe at extreme left of image carries lake water to condenser valves. - Ferry TICONDEROGA, Route 7, Shelburne, Chittenden County, VT

  1. Compound heat transfer enhancement for shell side of double-pipe heat exchanger by helical fins and vortex generators

    NASA Astrophysics Data System (ADS)

    Zhang, Li; Guo, Hongmei; Wu, Jianhua; Du, Wenjuan

    2012-07-01

    To improve heat transfer performance of shell side of double-pipe heat exchanger with helical fins on its inner tube, some vortex generators (VGs) were installed along the centerline of the helical channel. Heat transfer performance and pressure drop characteristic of the enhanced heat exchangers were investigated using air as the working fluid and steam as the heating medium. The helical fins were in the annulus and span its full width at different helical pitch. Wing-type VGs (delta or rectangular wing) and winglet-type VGs (delta or rectangular winglet pair) were used to combine with helical fins. The friction factor and Nusselt number can be well correlated by power-law correlations in the Reynolds number range studied. In order to evaluate the thermal performance of the shell side enhanced over the shell side without enhancement, comparisons were made under three constraints: (1) identical mass flow rate, IMF; (2) identical pressure drop, IPD and (3) identical pumping power, IPP. The results show the shell side enhanced by the compound heat transfer enhancement has better performance than the shell side only enhanced by helical fins at shorter helical pitch under the three constraints.

  2. Air Quality Side Event Proposal November 2016 GEO XIII ...

    EPA Pesticide Factsheets

    The Group on Earth Observations (GEO), which EPA has participated in since 2003, has put out a call for Side Events for its thirteenth annual international Plenary Meeting which is in St. Petersburg, Russia this year during November, 2016. EPA has put on Side Events on Air Quality and Health observational systems at eight of the previous Plenaries. This document is a Side Event proposal regarding air quality, health and next generation monitoring and observations techniques. It is submitted to the GEO Secretariat for consideration. If accepted, there will likely be presentations by EPA and NASA, other GEO Member Countries and UNEP and other GEO Participating Organizations at the Side Event. It is an opportunity to share scientific and technological advances in this area and build partnerships and collaboration. The Group on Earth Observations (GEO), which EPA has participated in since 2003, has put out a call for Side Events for its thirteenth annual international Plenary Meeting which is in St. Petersburg, Russia this year during November, 2016. EPA has put on Side Events on Air Quality and Health observational systems at eight of the previous Plenaries. This document is a Side Event proposal regarding air quality, health and next generation monitoring and observations techniques.  It is submitted to the GEO Secretariat for consideration. If accepted, there will likely be presentations by EPA and NASA, other GEO Member Countries and UNEP and other GEO P

  3. Oscillating side-branch enhancements of thermoacoustic heat exchangers

    DOEpatents

    Swift, Gregory W.

    2003-05-13

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

  4. The effectiveness of a heated air curtain

    NASA Astrophysics Data System (ADS)

    Frank, Daria

    2014-11-01

    Air curtains are high-velocity plane turbulent jets which are installed in the doorway in order to reduce the heat and the mass exchange between two environments. The air curtain effectiveness E is defined as the fraction of the exchange flow prevented by the air curtain compared to the open-door situation. In the present study, we investigate the effects of an opposing buoyancy force on the air curtain effectiveness. Such an opposing buoyancy force arises for example if a downwards blowing air curtain is heated. We conducted small-scale experiments using water as the working fluid with density differences created by salt and sugar. The effectiveness of a downwards blowing air curtain was measured for situations in which the initial density of the air curtain was less than both the indoor and the outdoor fluid density, which corresponds to the case of a heated air curtain. We compare the effectiveness of the heated air curtain to the case of the neutrally buoyant air curtain. It is found that the effectiveness starts to decrease if the air curtain is heated beyond a critical temperature. Furthermore, we propose a theoretical model to describe the dynamics of the buoyant air curtain. Numerical results obtained from solving this model corroborate our experimental findings.

  5. Air Conditioning and Heating Technology--II.

    ERIC Educational Resources Information Center

    Gattone, Felix

    Twenty-eight chapters and numerous drawings provide information for instructors and students of air conditioning and heating technology. Chapter 1 lists the occupational opportunities in the field. Chapter 2 covers the background or development of the industry of air conditioning and heating technology. Chapter 3 includes some of the principle…

  6. High frequency-heated air turbojet

    NASA Technical Reports Server (NTRS)

    Miron, J. H. D.

    1986-01-01

    A description is given of a method to heat air coming from a turbojet compressor to a temperature necessary to produce required expansion without requiring fuel. This is done by high frequency heating, which heats the walls corresponding to the combustion chamber in existing jets, by mounting high frequency coils in them. The current transformer and high frequency generator to be used are discussed.

  7. Steady-state computer design model for air-to-air heat pumps

    NASA Astrophysics Data System (ADS)

    Fischer, S. K.; Rice, C. K.

    1981-12-01

    A FORTRAN-4 computer program to predict the steady-state performance of conventional, vapor compression, electrically-driven, air-to-air heat pumps in both heating and cooling modes is described. This model is intended to serve as an analytical design tool for use by heat pump manufacturers, consulting engineers, research institutions, and universities in studies directed toward the improvement of heat pump performance. The heat pump design model allows the user to specify: system operating conditions, compressor characteristics, refrigerant flow control devices, fin-and-tube heat exchanger parameters, fan and indoor duct characteristics, and any of ten refrigerants. The model will compute: system capacity and COP (or EER), compressor and fan motor power consumptions, coil outlet air dry- and wet-bulb temperatures, air- and refrigerant-side pressure drops, a summary of the refrigerant-side states throughout the cycle, and overall compressor efficiencies and heat exchanger effectiveness. Documentation of how to use and/or modify the model is provided.

  8. The Energy Implications of Air-Side Fouling in Constant Air Volume HVAC Systems

    NASA Astrophysics Data System (ADS)

    Wilson, Eric J. H.

    2011-12-01

    This thesis examines the effect of air-side fouling on the energy consumption of constant air volume (CAV) heating, ventilating, and air conditioning (HVAC) systems in residential and small commercial buildings. There is a particular focus on evaluating the potential energy savings that may result from the remediation of such fouling from coils, filters, and other air system components. A computer model was constructed to simulate the behavior of a building and its duct system under various levels of fouling. The model was verified through laboratory and field testing and then used to run parametric simulations to examine the range of energy impacts for various climates and duct system characteristics. A sensitivity analysis was conducted to determine the impact of parameters like duct insulation, duct leakage, duct location, and duct design on savings potential. Duct system pressures, temperatures, and energy consumption for two houses were monitored for one month. The houses' duct systems, which were both in conditioned space, were given a full cleaning, and were then monitored for another month. The flow rates at the houses improved by 10% and 6%. The improvements were primarily due to installing a new filter, as both houses had only light coil fouling. The results indicate that there was negligible change in heating energy efficiency due to the system cleaning. The parametric simulation results are in agreement with the field experiment: for systems in all eight climates, with flowrates degraded by 20% or less, if ducts are located within the thermal zone, HVAC source energy savings from cleaning are negligible or even slightly negative. However, if ducts are outside the thermal zone, savings are in the 1 to 5% range. For systems with flowrates degraded by 40%, if ducts are within the thermal zone, savings from cleaning occurs only for air conditioning energy, up to 8% in climates like Miami, FL. If ducts are outside the thermal zone, savings occurs with both

  9. Pressure Drop and Heat Transfer of Water Flowing Shell-Side of Multitube Heat Exchangers

    NASA Astrophysics Data System (ADS)

    Ohashi, Yukio; Hashizume, Kenichi

    Experimental studies on heat transfer augmentation in water-flowing shell sides of counter flow multitube exchangers are presented. Various kinds of augmented tube bundles have been examined to obtain the characteristics of pressure drop and heat transfer. Data for a smooth tube bundle were a little different from those for the tube side. The pressure drop in the shell side depended on Re-0.4 and deviated from the tube side pressure drop to within +30%, while the shell side heat transfer coefficient depended on Re0.8 but about 35%. larger than that of the tube side. Furthermore the augmented tube bundles have been evaluated and compared using 21 evaluation criteria. Enhanced tube bundles, low-finned tube bundles and those with twisted tapes inserted had especially good performances. The ratios of increase in heat transfer were larger than those in pressure drop. In case of low-finned tube bundles, there seem to exist an optimum fin-pitch and an optimum relation between the fin-pitch and the pitch of twisted tapes inserted.

  10. Numerical investigation of boiling heat transfer on the shell-side of spiral wound heat exchanger

    NASA Astrophysics Data System (ADS)

    Wu, Zhi-Yong; Wang, He; Cai, Wei-Hua; Jiang, Yi-Qiang

    2016-09-01

    The aim of this paper is to numerically study boiling heat transfer on the shell-side of spiral wound heat exchanger (SWHE). The physical model for the shell-side of SWHE is established and the volume of fluid (VOF) method is used in the calculation. For propane and ethane, there are thirty cases to be simulated . Through the comparison with experimental data, the cause which leads to the simulation distortion is found, and the satisfied results of calculation are finally achieved. The simulation results show that the VOF model can be adopted well to those calculations whose inlet quality are lower than 0.1 kg/kg, and the calculation deviations are generally within ±20 %. In falling film flow, the heat transfer performance for the shell-side of SWHE is primarily influenced by Reynolds number. The visualization of simulation results displays that the boiling bubbles have three flow directions, besides flowing down with liquid phase, one portion of bubbles flows reversely up, and another portion is blocked at axial gaps of coils where the heat transfer is reduced. The studies of boiling on the shell-side of SWHE not only reveal the characteristics of heat transfer, but also point out the improvement direction of SWHE.

  11. Parametric study of fluid flow and heat transfer over louvered fins of air heat pump evaporator

    NASA Astrophysics Data System (ADS)

    Muszyński, Tomasz; Kozieł, Sławomir Marcin

    2016-09-01

    Two-dimensional numerical investigations of the fluid flow and heat transfer have been carried out for the laminar flow of the louvered fin-plate heat exchanger, designed to work as an air-source heat pump evaporator. The transferred heat and the pressure drop predicted by simulation have been compared with the corresponding experimental data taken from the literature. Two dimensional analyses of the louvered fins with varying geometry have been conducted. Simulations have been performed for different geometries with varying louver pitch, louver angle and different louver blade number. Constant inlet air temperature and varying velocity ranging from 2 to 8 m/s was assumed in the numerical experiments. The air-side performance is evaluated by calculating the temperature and the pressure drop ratio. Efficiency curves are obtained that can be used to select optimum louver geometry for the selected inlet parameters. A total of 363 different cases of various fin geometry for 7 different air velocities were investigated. The maximum heat transfer improvement interpreted in terms of the maximum efficiency has been obtained for the louver angle of 16 ° and the louver pitch of 1.35 mm. The presented results indicate that varying louver geometry might be a convenient way of enhancing performance of heat exchangers.

  12. 5. PHOTOGRAPHIC COPY OF ORIGINAL DRAWINGS, ELECTRIC AIR AND HEATING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. PHOTOGRAPHIC COPY OF ORIGINAL DRAWINGS, ELECTRIC AIR AND HEATING UNIT, PLAN AND ELEVATION - Wyoming Air National Guard Base, Electric, Air & Heating Plant, Cheyenne Airport, Cheyenne, Laramie County, WY

  13. Modelling heat and mass transfer in a membrane-based air-to-air enthalpy exchanger

    NASA Astrophysics Data System (ADS)

    Dugaria, S.; Moro, L.; Del, D., Col

    2015-11-01

    The diffusion of total energy recovery systems could lead to a significant reduction in the energy demand for building air-conditioning. With these devices, sensible heat and humidity can be recovered in winter from the exhaust airstream, while, in summer, the incoming air stream can be cooled and dehumidified by transferring the excess heat and moisture to the exhaust air stream. Membrane based enthalpy exchangers are composed by different channels separated by semi-permeable membranes. The membrane allows moisture transfer under vapour pressure difference, or water concentration difference, between the two sides and, at the same time, it is ideally impermeable to air and other contaminants present in exhaust air. Heat transfer between the airstreams occurs through the membrane due to the temperature gradient. The aim of this work is to develop a detailed model of the coupled heat and mass transfer mechanisms through the membrane between the two airstreams. After a review of the most relevant models published in the scientific literature, the governing equations are presented and some simplifying assumptions are analysed and discussed. As a result, a steady-state, two-dimensional finite difference numerical model is setup. The developed model is able to predict temperature and humidity evolution inside the channels. Sensible and latent heat transfer rate, as well as moisture transfer rate, are determined. A sensitive analysis is conducted in order to determine the more influential parameters on the thermal and vapour transfer.

  14. [Air quality control systems: heating, ventilating, and air conditioning (HVAC)].

    PubMed

    Bellucci Sessa, R; Riccio, G

    2004-01-01

    After a brief illustration of the principal layout schemes of Heating, Ventilating, and Air Conditioning (HVAC), the first part of this paper summarizes the standards, both voluntary and compulsory, regulating HVAC facilities design and installation with regard to the question of Indoor Air Quality (IAQ). The paper then examines the problem of ventilation systems maintenance and the essential hygienistic requirements in whose absence HVAC facilities may become a risk factor for people working or living in the building. Lastly, the paper deals with HVAC design strategies and methods, which aim not only to satisfy comfort and air quality requirements, but also to ensure easy and effective maintenance procedures.

  15. Development of an Air-Source Heat Pump Integrated with a Water Heating / Dehumidification Module

    SciTech Connect

    Rice, C Keith; Uselton, Robert B.; Shen, Bo; Baxter, Van D; Shrestha, Som S

    2014-01-01

    A residential-sized dual air-source integrated heat pump (AS-IHP) concept is under development in partnership between ORNL and a manufacturer. The concept design consists of a two-stage air-source heat pump (ASHP) coupled on the air distribution side with a separate novel water heating/dehumidification (WH/DH) module. The motivation for this unusual equipment combination is the forecast trend for home sensible loads to be reduced more than latent loads. Integration of water heating with a space dehumidification cycle addresses humidity control while performing double-duty. This approach can be applied to retrofit/upgrade applications as well as new construction. A WH/DH module capable of ~1.47 L/h water removal and ~2 kW water heating capacity was assembled by the manufacturer. A heat pump system model was used to guide the controls design; lab testing was conducted and used to calibrate the models. Performance maps were generated and used in a TRNSYS sub-hourly simulation to predict annual performance in a well-insulated house. Annual HVAC/WH energy savings of ~35% are predicted in cold and hot-humid U.S. climates compared to a minimum efficiency baseline.

  16. Standardized Curriculum for Heating and Air Conditioning.

    ERIC Educational Resources Information Center

    Mississippi State Dept. of Education, Jackson. Office of Vocational, Technical and Adult Education.

    Standardized vocational education course titles and core contents for two courses in Mississippi are provided: heating and air conditioning I and II. The first course contains the following units: (1) orientation; (2) safety; (3) refrigeration gauges and charging cylinder; (4) vacuum pump service operations; (5) locating refrigerant leaks; (6)…

  17. Convective heat transfer in a high aspect ratio minichannel heated on one side

    SciTech Connect

    Forrest, Eric C.; Hu, Lin -Wen; Buongiorno, Jacopo; McKrell, Thomas J.

    2015-10-21

    Experimental results are presented for single-phase heat transfer in a narrow rectangular minichannel heated on one side. The aspect ratio and gap thickness of the test channel were 29:1 and 1.96 mm, respectively. Friction pressure drop and Nusselt numbers are reported for the transition and fully turbulent flow regimes, with Prandtl numbers ranging from 2.2 to 5.4. Turbulent friction pressure drop for the high aspect ratio channel is well-correlated by the Blasius solution when a modified Reynolds number, based upon a laminar equivalent diameter, is utilized. The critical Reynolds number for the channel falls between 3500 and 4000, with Nusselt numbers in the transition regime being reasonably predicted by Gnielinski's correlation. The dependence of the heat transfer coefficient on the Prandtl number is larger than that predicted by circular tube correlations, and is likely a result of the asymmetric heating. The problem of asymmetric heating condition is approached theoretically using a boundary layer analysis with a two-region wall layer model, similar to that originally proposed by Prandtl. The analysis clarifies the influence of asymmetric heating on the Nusselt number and correctly predicts the experimentally observed trend with Prandtl number. Furthermore, a semi-analytic correlation is derived from the analysis that accounts for the effect of aspect ratio and asymmetric heating, and is shown to predict the experimental results of this study with a mean absolute error (MAE) of less than 5% for 4000 < Re < 70,000.

  18. Performance Assessment of Sodium to Air Finned Heat Exchanger for FBR

    SciTech Connect

    Noushad, I.B.; Ellappan, T.R.; Rajan, K.K.; Rajan, M.; Vaidyanathan, G.; Vinod, V.; Suresh Kumar, V.A.

    2006-07-01

    In pool type Fast Breeder Reactors (FBR) a passive Safety Grade Decay Heat Removal (SGDHR) system removes decay heat produced in the core when normal heat removal path through steam water system is not available. This is essential to maintain the core temperatures within limits. A Decay Heat Exchanger (DHX) picks the heat from the pool and transfers the heat to atmosphere through sodium to Air Heat Exchanger (AHX) situated at high elevation. Due to the temperature differences existent in the system density differences are generated causing a buoyant convective heat transfer. The system is completely passive as primary sodium, secondary sodium and air flows under natural convection. DHX is a sodium to sodium counter flow heat exchanger with primary sodium on shell side and secondary sodium on tube side. AHX is a cross flow heat exchanger with sodium on tube side and air flows in cross flow across the finned tubes. Capacity of a single loop of SGDHR is 8 MW. Four such loops are available for the decay heat removal. It has been seen that the decay heat removal to a large extent depends on the AHX performance. AHX tested have shown reduced heat removal capacity much as 30 to 40%, essentially due to the bypassing of the finned tubes by the air. It was felt that a geometrically similar AHX be tested in sodium. Towards this a 2 MW Sodium to air heat exchanger (AHX) was tested in the Steam Generator Test Facility (SGTF) constructed at Indira Gandhi Center for Atomic Research (IGCAR), Kalpakkam. The casing arrangement of the AHX was designed to minimise bypassing of air. (authors)

  19. Air-to-air heat exchangers and the indoor environment

    SciTech Connect

    Vine, E.

    1987-02-01

    Air-to-air heat exchangers were installed in 366 energy-efficient homes as part of a demonstration program in the United States. The median incremental cost of AAHX was $1268 ($7.42/mS), and it was less expensive (per square meter) to install this equipment in larger houses than in smaller houses. While most occupants did not notice problems with their AAHX, some households did experience problems related to noise, unpleasant drafts, condensation around the AAHX, and core freezing. Occupants of energy-efficient homes were found to have less problems with their indoor environment (especially mildew/mold and condensation) than a group of control homes.

  20. The Oak Ridge Heat Pump Models: I. A Steady-State Computer Design Model of Air-to-Air Heat Pumps

    SciTech Connect

    Fischer, S.K. Rice, C.K.

    1999-12-10

    The ORNL Heat Pump Design Model is a FORTRAN-IV computer program to predict the steady-state performance of conventional, vapor compression, electrically-driven, air-to-air heat pumps in both heating and cooling modes. This model is intended to serve as an analytical design tool for use by heat pump manufacturers, consulting engineers, research institutions, and universities in studies directed toward the improvement of heat pump performance. The Heat Pump Design Model allows the user to specify: system operating conditions, compressor characteristics, refrigerant flow control devices, fin-and-tube heat exchanger parameters, fan and indoor duct characteristics, and any of ten refrigerants. The model will compute: system capacity and COP (or EER), compressor and fan motor power consumptions, coil outlet air dry- and wet-bulb temperatures, air- and refrigerant-side pressure drops, a summary of the refrigerant-side states throughout the cycle, and overall compressor efficiencies and heat exchanger effectiveness. This report provides thorough documentation of how to use and/or modify the model. This is a revision of an earlier report containing miscellaneous corrections and information on availability and distribution of the model--including an interactive version.

  1. Convective heat transfer in a high aspect ratio minichannel heated on one side

    DOE PAGES

    Forrest, Eric C.; Hu, Lin -Wen; Buongiorno, Jacopo; ...

    2015-10-21

    Experimental results are presented for single-phase heat transfer in a narrow rectangular minichannel heated on one side. The aspect ratio and gap thickness of the test channel were 29:1 and 1.96 mm, respectively. Friction pressure drop and Nusselt numbers are reported for the transition and fully turbulent flow regimes, with Prandtl numbers ranging from 2.2 to 5.4. Turbulent friction pressure drop for the high aspect ratio channel is well-correlated by the Blasius solution when a modified Reynolds number, based upon a laminar equivalent diameter, is utilized. The critical Reynolds number for the channel falls between 3500 and 4000, with Nusseltmore » numbers in the transition regime being reasonably predicted by Gnielinski's correlation. The dependence of the heat transfer coefficient on the Prandtl number is larger than that predicted by circular tube correlations, and is likely a result of the asymmetric heating. The problem of asymmetric heating condition is approached theoretically using a boundary layer analysis with a two-region wall layer model, similar to that originally proposed by Prandtl. The analysis clarifies the influence of asymmetric heating on the Nusselt number and correctly predicts the experimentally observed trend with Prandtl number. Furthermore, a semi-analytic correlation is derived from the analysis that accounts for the effect of aspect ratio and asymmetric heating, and is shown to predict the experimental results of this study with a mean absolute error (MAE) of less than 5% for 4000 < Re < 70,000.« less

  2. Air Heating Associated with Transient Luminous Events

    NASA Astrophysics Data System (ADS)

    Riousset, J. A.; Pasko, V. P.; Bourdon, A.

    2009-12-01

    The understanding of ambient gas heating processes initiated by needle-shaped filaments of ionization, called streamers, embedded in originally cold air (near room temperature) represents a long standing problem, which is of interest for studies of long laboratory sparks and natural lightning discharges [e.g., Gallimberti et al., C. R. Physique, 3, 1335, 2002]. The observed phenomenology of a subset of the recently observed transient luminous events in the middle atmosphere, which originate from thundercloud tops [e.g, Wescott et al., JGR, 106, 21549, 2001; Pasko et al., Nature, 416, 152, 2002; Su et al., Nature, 423, 974, 2003; Krehbiel et al., Nature Geoscience, 1, 233, 2008; Cummer et al., Nature Geoscience, 2, 617, 2009, Riousset et al., JGR, 10.1029/2009JA014286, 2009, in press], indicate that these events may be related to conventional lightning leader processes and therefore are associated with significant heating of the air in the regions of atmosphere through which they propagate [Pasko and George, JGR, 107, 1458, 2002]. Many of the small scale features observed in sprites at higher altitudes [e.g., Stenbaek-Nielsen et al., GRL, 104, L11105, 2007, and references therein] can be interpreted in terms of corona streamers, which, after appropriate scaling with air density, are fully analogous to those, which initiate spark discharges in relatively short (several cm) gaps at near ground pressure [Liu et al., JGR, 114, A00E03, 2009, and references therein] and which constitute building blocks of streamer zones of conventional lightning leaders in long gaps [Gallimberti et al., 2002]. The recent reports of infrasound bursts originating from 60-80 km altitudes in sprites, with durations consistent with the optical widths of the sprites [e.g., Farges, in Lightning: Principles, Instruments and Applications, p. 417, Betz et al., (eds.), Springer, 2009], provide an additional motivation for studies of the heating of the ambient air and associated chemical effects

  3. The effects of air leaks on solar air heating systems

    NASA Technical Reports Server (NTRS)

    Elkin, R.; Cash, M.

    1979-01-01

    This paper presents the results of an investigation to determine the effects of leakages in collector and duct work on the system performance of a typical single-family residence solar air heating system. Positive (leakage out) and negative (leakage in) pressure systems were examined. Collector and duct leakage rates were varied from 10 to 30 percent of the system flow rate. Within the range of leakage rates investigated, solar contribution to heated space and domestic hot water loads was found to be reduced up to 30 percent from the no-leak system contribution with duct leakage equally divided between supply and return duct; with supply duct leakage greater than return leakage a reduction of up to 35 percent was noted. The negative pressure system exhibited a reduction in solar contribution somewhat larger than the positive pressure system for the same leakage rates.

  4. Solar assisted heat pump on air collectors: A simulation tool

    SciTech Connect

    Karagiorgas, Michalis; Galatis, Kostas; Tsagouri, Manolis; Tsoutsos, Theocharis; Botzios-Valaskakis, Aristotelis

    2010-01-15

    The heating system of the bioclimatic building of the Greek National Centre for Renewable Energy Sources (CRES) comprises two heating plants: the first one includes an air source heat pump, Solar Air Collectors (SACs) and a heat distribution system (comprising a fan coil unit network); the second one is, mainly, a geothermal heat pump unit to cover the ground floor thermal needs. The SAC configuration as well as the fraction of the building heating load covered by the heating plant are assessed in two operation modes; the direct (hot air from the collectors is supplied directly to the heated space) and the indirect mode (warm air from the SAC or its mixture with ambient air is not supplied directly to the heated space but indirectly into the evaporator of the air source heat pump). The technique of the indirect mode of heating aims at maximizing the efficiency of the SAC, saving electrical power consumed by the compressor of the heat pump, and therefore, at optimizing the coefficient of performance (COP) of the heat pump due to the increased intake of ambient thermal energy by means of the SAC. Results are given for three research objectives: assessment of the heat pump efficiency whether in direct or indirect heating mode; Assessment of the overall heating plant efficiency on a daily or hourly basis; Assessment of the credibility of the suggested simulation model TSAGAIR by comparing its results with the TRNSYS ones. (author)

  5. Refrigeration, Heating & Air Conditioning. Post Secondary Curriculum Guide.

    ERIC Educational Resources Information Center

    Garrison, Joe C.; And Others

    This curriculum guide was designed for use in postsecondary refrigeration, heating and air conditioning education programs in Georgia. Its purpose is to provide for the development of entry level skills in refrigeration, heating, and air conditioning in the areas of air conditioning knowledge, theoretical structure, tool usage, diagnostic ability,…

  6. The heat transfer of cooling fins on moving air

    NASA Technical Reports Server (NTRS)

    Doetsch, Hans

    1935-01-01

    The present report is a comparison of the experimentally defined temperature and heat output of cooling fins in the air stream with theory. The agreement is close on the basis of a mean coefficient of heat transfer with respect to the total surface. A relationship is established between the mean coefficient of heat transfer, the dimensions of the fin arrangement, and the air velocity.

  7. Computer cooling using a two phase minichannel thermosyphon loop heated from horizontal and vertical sides and cooled from vertical side

    NASA Astrophysics Data System (ADS)

    Bieliński, Henryk; Mikielewicz, Jarosław

    2010-10-01

    In the present paper it is proposed to consider the computer cooling capacity using the thermosyphon loop. A closed thermosyphon loop consists of combined two heaters and a cooler connected to each other by tubes. The first heater may be a CPU processor located on the motherboard of the personal computer. The second heater may be a chip of a graphic card placed perpendicular to the motherboard of personal computer. The cooler can be placed above the heaters on the computer chassis. The thermosyphon cooling system on the use of computer can be modeled using the rectangular thermosyphon loop with minichannels heated at the bottom horizontal side and the bottom vertical side and cooled at the upper vertical side. The riser and a downcomer connect these parts. A one-dimensional model of two-phase flow and heat transfer in a closed thermosyphon loop is based on mass, momentum, and energy balances in the evaporators, rising tube, condenser and the falling tube. The separate two-phase flow model is used in calculations. A numerical investigation for the analysis of the mass flux rate and heat transfer coefficient in the steady state has been accomplished.

  8. 21 CFR 211.46 - Ventilation, air filtration, air heating and cooling.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 4 2012-04-01 2012-04-01 false Ventilation, air filtration, air heating and cooling. 211.46 Section 211.46 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... Buildings and Facilities § 211.46 Ventilation, air filtration, air heating and cooling. (a)...

  9. 21 CFR 211.46 - Ventilation, air filtration, air heating and cooling.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 4 2013-04-01 2013-04-01 false Ventilation, air filtration, air heating and cooling. 211.46 Section 211.46 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... Buildings and Facilities § 211.46 Ventilation, air filtration, air heating and cooling. (a)...

  10. 21 CFR 211.46 - Ventilation, air filtration, air heating and cooling.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 4 2014-04-01 2014-04-01 false Ventilation, air filtration, air heating and cooling. 211.46 Section 211.46 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... Buildings and Facilities § 211.46 Ventilation, air filtration, air heating and cooling. (a)...

  11. 21 CFR 211.46 - Ventilation, air filtration, air heating and cooling.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 4 2011-04-01 2011-04-01 false Ventilation, air filtration, air heating and cooling. 211.46 Section 211.46 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... Buildings and Facilities § 211.46 Ventilation, air filtration, air heating and cooling. (a)...

  12. A survey of gas-side fouling in industrial heat-transfer equipment

    NASA Technical Reports Server (NTRS)

    Marner, W. J.; Suitor, J. W.

    1983-01-01

    Gas-side fouling and corrosion problems occur in all of the energy intensive industries including the chemical, petroleum, primary metals, pulp and paper, glass, cement, foodstuffs, and textile industries. Topics of major interest include: (1) heat exchanger design procedures for gas-side fouling service; (2) gas-side fouling factors which are presently available; (3) startup and shutdown procedures used to minimize the effects of gas-side fouling; (4) gas-side fouling prevention, mitigation, and accommodation techniques; (5) economic impact of gas-side fouling on capital costs, maintenance costs, loss of production, and energy losses; and (6) miscellaneous considerations related to gas-side fouling. The present state-of-the-art for industrial gas-side fouling is summarized by a list of recommendations for further work in this area.

  13. A survey of gas-side fouling in industrial heat-transfer equipment

    NASA Astrophysics Data System (ADS)

    Marner, W. J.; Suitor, J. W.

    1983-11-01

    Gas-side fouling and corrosion problems occur in all of the energy intensive industries including the chemical, petroleum, primary metals, pulp and paper, glass, cement, foodstuffs, and textile industries. Topics of major interest include: (1) heat exchanger design procedures for gas-side fouling service; (2) gas-side fouling factors which are presently available; (3) startup and shutdown procedures used to minimize the effects of gas-side fouling; (4) gas-side fouling prevention, mitigation, and accommodation techniques; (5) economic impact of gas-side fouling on capital costs, maintenance costs, loss of production, and energy losses; and (6) miscellaneous considerations related to gas-side fouling. The present state-of-the-art for industrial gas-side fouling is summarized by a list of recommendations for further work in this area.

  14. Heat recovery and air preheating apparatus for textile dryer ovens

    SciTech Connect

    Hebrank, W.H.

    1982-07-06

    Heat recovery and replacement air preheating apparatus for use in textile heat treatment machinery is disclosed as including a pair of thermal recovery and storage units wherein each storage unit contains a plurality of thermal mass disks which operate as heat sponges to pick up heat from exhausts as it leaves the dryer and subsequently to put that heat into entering replacement air whereby the cost in elevating the replacement air is greatly reduced. A control valve connected between the two thermal storage units cycles the reverse exhaust and replacement air flows alternately through the thermal storage units in a manner that a substantial amount of the exhaust heat does not reach the ambient environment and the alternating replacement air flow maintains the thermal heat recovery and storage units and associated apparatus cool and clean of lint and the like residuals.

  15. Recent trends (2003-2013) of land surface heat fluxes on the southern side of the central Himalayas, Nepal

    NASA Astrophysics Data System (ADS)

    Amatya, Pukar Man; Ma, Yaoming; Han, Cunbo; Wang, Binbin; Devkota, Lochan Prasad

    2015-12-01

    Novice efforts have been made in order to study the regional distribution of land surface heat fluxes on the southern side of the central Himalayas utilizing high-resolution remotely sensed products, but these have been on instantaneous scale. In this study the Surface Energy Balance System model is used to obtain annual averaged maps of the land surface heat fluxes for 11 years (2003-2013) and study their annual trends on the central Himalayan region. The maps were derived at 5 km resolution using monthly input products ranging from satellite derived to Global Land Data Assimilation System meteorological data. It was found that the net radiation flux is increasing as a result of decreasing precipitation (drier environment). The sensible heat flux did not change much except for the northwestern High Himalaya and High Mountains. In northwestern High Himalaya sensible heat flux is decreasing because of decrease in wind speed, ground-air temperature difference, and increase in winter precipitation, whereas in High Mountains it is increasing due to increase in ground-air temperature difference and high rate of deforestation. The latent heat flux has an overall increasing trend with increase more pronounced in the lower regions compared to high elevated regions. It has been reported that precipitation is decreasing with altitude in this region. Therefore, the increasing trend in latent heat flux can be attributed to increase in net radiation flux under persistent forest cover and irrigation land used for agriculture.

  16. Dry/wet performance of a plate-fin air-cooled heat exchanger with continuous corrugated fins

    SciTech Connect

    Hauser, S.G.; Kreid, D.K.; Johnson, B.M.

    1981-01-01

    The performance and operating characteristics of a plate-fin heat exchanger in dry/wet or deluge operations was experimentally determined. Development of the deluge heat/mass transfer model continued. The experiments were conducted in a specially-designed wind tunnel at the PNL. Air that was first heated and humidified to specified conditions was circulated at a controlled rate through a 2 ft x 6 ft heat exchanger module. The heat exchanger used in the tests was a wavy surface, plate fin on tube configuration. Hot water was circulated through the tubes at high flow rates to maintain an essentially isothermal condition on the tube side. Deionized water sprayed on the top of the vertically oriented plate fins was collected at the bottom of the core and recirculated. Instrumentation was provided for measurement of flow rates and thermodynamic conditions in the air, in the core circulation water, and in the deluge water. Measurements of the air side pressure drop and heat rejection rate were made as a function of air flow rate, air inlet temperature and humidity, deluge water flow rate, and the core inclination from the vertical. An overall heat transfer coefficient and an effective deluge film convective coefficient was determined. The deluge model, for predicting heat transfer from a wet finned heat exchanger was further developed and refined, and a major extension of the model was formulated that permits simultaneous calculation of both the heat transfer and evaporation rates from the wetted surface. The experiments showed an increase in the heat rejection rate due to wetting, accompanied by a proportional increase in the air side pressure drop. For operation at the same air side pressure drop, the enhancement ratio Q/sub w//Q/sub d/ varied between 2 and 5 for the conditions tested. Thus, the potential enhancement of heat transfer due to wetting can be substantial.

  17. 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

    2017-01-01

    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.

  18. Prestressing buried pipelines by heating with air

    SciTech Connect

    King, G. )

    1993-11-01

    Buried pipelines operating at elevated temperatures experience high longitudinal compressive stresses because the surrounding soil prevents thermal expansion. At high operating temperatures, buried pipelines can push through the soil at bends and buckle catastrophically. In soft soils they can lose lateral stability, and they can develop plastic failures. Thermally induced problems can be prevented with varying degrees of success by using thicker wall pipe, higher strength prevented with varying degrees of success by using thicker wall pipe, higher strength steel, longer radius bends, deeper burial, better backfill compaction, and/or prestressing during construction. Prestressing is most appropriate for pipelines operating at temperatures more than 80 C above ambient. One technique for prestressing a buried pipeline, that has been found to be both easy and economical for a liquid sulfur pipeline in Alberta, is to heat it with hot air and bury it while it is still hot. Pipe diameter and prestressing temperature both have a significant impact on the kind of heating equipment that is required.

  19. Heat Waves, Urban Vegetation, and Air Pollution

    NASA Astrophysics Data System (ADS)

    Churkina, G.; Grote, R.; Butler, T. M.

    2014-12-01

    Fast-track programs to plant millions of trees in cities around the world aim at the reduction of summer temperatures, increase carbon storage, storm water control, provision of space for recreation, as well as poverty alleviation. Although these multiple benefits speak positively for urban greening programs, the programs do not take into account how close human and natural systems are coupled in urban areas. Elevated temperatures together with anthropogenic emissions of air and water pollutants distinguish the urban system. Urban and sub-urban vegetation responds to ambient changes and reacts with pollutants. Neglecting the existence of this coupling may lead to unforeseen drawbacks of urban greening programs. The potential for emissions from urban vegetation combined with anthropogenic emissions to produce ozone has long been recognized. This potential increases under rising temperatures. Here we investigate how global change induced heat waves affect emissions of volatile organic compounds (VOC) from urban vegetation and corresponding ground-level ozone levels. We also quantify other ecosystem services provided by urban vegetation (e.g., cooling and carbon storage) and their sensitivity to climate change. In this study we use Weather Research and Forecasting Model with coupled atmospheric chemistry (WRF-CHEM) to quantify these feedbacks in Berlin, Germany during the heat waves in 2003 and 2006. We highlight the importance of the vegetation for urban areas under changing climate and discuss associated tradeoffs.

  20. Air Quality Side Event Proposal November 2016 GEO XIII Plenary in St. Petersburg, Russia

    EPA Science Inventory

    The Group on Earth Observations (GEO), which EPA has participated in since 2003, has put out a call for Side Events for its thirteenth annual international Plenary Meeting which is in St. Petersburg, Russia this year during November, 2016. EPA has put on Side Events on Air Quali...

  1. Selection of the air heat exchanger operating in a gas turbine air bottoming cycle

    NASA Astrophysics Data System (ADS)

    Chmielniak, Tadeusz; Czaja, Daniel; Lepszy, Sebastian

    2013-12-01

    A gas turbine air bottoming cycle consists of a gas turbine unit and the air turbine part. The air part includes a compressor, air expander and air heat exchanger. The air heat exchanger couples the gas turbine to the air cycle. Due to the low specific heat of air and of the gas turbine exhaust gases, the air heat exchanger features a considerable size. The bigger the air heat exchanger, the higher its effectiveness, which results in the improvement of the efficiency of the gas turbine air bottoming cycle. On the other hand, a device with large dimensions weighs more, which may limit its use in specific locations, such as oil platforms. The thermodynamic calculations of the air heat exchanger and a preliminary selection of the device are presented. The installation used in the calculation process is a plate heat exchanger, which is characterized by a smaller size and lower values of the pressure drop compared to the shell and tube heat exchanger. Structurally, this type of the heat exchanger is quite similar to the gas turbine regenerator. The method on which the calculation procedure may be based for real installations is also presented, which have to satisfy the economic criteria of financial profitability and cost-effectiveness apart from the thermodynamic criteria.

  2. Experimental determination of forces in a rigidly constrained rod of composite material heated on one side

    SciTech Connect

    Pervushin, Yu.S.; Valiev, R.S.

    1987-03-01

    An installation and a method for investigating thermal forces and strains in structural elements type rods, plates and panels of composite polymer materials subjected to one-sided heating are presented. A diagram of the installation for investigating the thermal forces in structural elements of heat-insulating materials subjected to one-sided heating is shown. The dependences of the support membrane forces and bending moments in the rod on the temperature in one-sided heating were established. The nature of the change of the thermal forces depends on the speed and depth of penetration of the front of temperatures exceeding the temperature of onset of destruction into the section of the material. During cooling, the tensile forces and bending moments continue to increase.

  3. Heat Transfer from Finned Metal Cylinders in an Air Stream

    NASA Technical Reports Server (NTRS)

    Biermann, Arnold, E; Pinkel, Benjamin

    1935-01-01

    This report presents the results of tests made to supply design information for the construction of metal fins for the cooling of heated cylindrical surfaces by an air stream. A method is given for determining fin dimensions for a maximum heat transfer with the expenditure of a given amount of material for a variety of conditions of air flow and metals.

  4. Mountain Plains Learning Experience Guide: Heating, Refrigeration, & Air Conditioning.

    ERIC Educational Resources Information Center

    Carey, John

    This Heating, Refrigeration, and Air Conditioning course is comprised of eleven individualized units: (1) Refrigeration Tools, Materials, and Refrigerant; (2) Basic Heating and Air Conditioning; (3) Sealed System Repairs; (4) Basic Refrigeration Systems; (5) Compression Systems and Compressors; (6) Refrigeration Controls; (7) Electric Circuit…

  5. Dynamic Performance of a Residential Air-to-Air Heat Pump.

    ERIC Educational Resources Information Center

    Kelly, George E.; Bean, John

    This publication is a study of the dynamic performance of a 5-ton air-to-air heat pump in a residence in Washington, D.C. The effect of part-load operation on the heat pump's cooling and heating coefficients of performance was determined. Discrepancies between measured performance and manufacturer-supplied performance data were found when the unit…

  6. Cold Climate and Retrofit Applications for Air-to-Air Heat Pumps

    SciTech Connect

    Baxter, Van D

    2015-01-01

    Air source heat pumps (ASHP) including air-to-air ASHPs are easily applied to buildings almost anywhere for new construction as well as retrofits or renovations. They are widespread in milder climate regions but their use in cold regions is hampered due to low heating efficiency and capacity at cold outdoor temperatures. Retrofitting air-to-air ASHPs to existing buildings is relatively easy if the building already has an air distribution system. For buildings without such systems alternative approaches are necessary. Examples are ductless, minisplit heat pumps or central heat pumps coupled to small diameter, high velocity (SDHV) air distribution systems. This article presents two subjects: 1) a summary of R&D investigations aimed at improving the cold weather performance of ASHPs, and 2) a brief discussion of building retrofit options using air-to-air ASHP systems.

  7. Average heat-transfer characteristics of a row of circular air jets impinging on a concave surface

    NASA Technical Reports Server (NTRS)

    Livingood, J. N. B.; Gauntner, J. W.

    1972-01-01

    A study of the average heat-transfer characteristics of air jets impinging on the concave side of a right-circular semicylinder is reported. Results from existing correlating are compared with each other and with experimental heat-transfer data for a row of circular jets. Two correlations available in the literature are recommended for use in designing cooled turbine vanes and blades.

  8. Investigating the urban heat island effect on air quality

    NASA Astrophysics Data System (ADS)

    Loughner, C. P.; Allen, D. J.; Dickerson, R. R.; Pickering, K. E.; Shou, Y.; Zhang, D.

    2009-12-01

    Urbanization impacts meteorology and air quality in and downwind of cities. An urban heat island can increase the temperature in and downwind of cities. An increase in temperature may worsen air quality by increasing the amount of photochemically produced ozone. During an air pollution episode on July 9, 2007, in which 8-hour maximum ozone and 24-hour average PM2.5 concentrations reached 125ppb and 40μg/m3 respectively, the Washington, DC urban heat island propagated downwind over Columbia, MD and then Baltimore, MD further amplifying the temperature in and downwind of Baltimore. With the use of the Weather Research and Forecasting model coupled with an urban canopy model (WRF/UCM) and EPA’s Community Multi-scale Air Quality (CMAQ) model, the air quality is analyzed within the urban heat island. In addition, the interactions between the Chesapeake Bay breeze, the urban heat island, and the air chemistry are analyzed.

  9. Indoor air pollution by different heating systems: coal burning, open fireplace and central heating.

    PubMed

    Moriske, H J; Drews, M; Ebert, G; Menk, G; Scheller, C; Schöndube, M; Konieczny, L

    1996-11-01

    Investigations of indoor air pollution by different heating systems in private homes are described. Sixteen homes, 7 with coal burning, 1 with open fireplace (wood burning) and 8 with central heating have been investigated. We measured the concentrations of carbon monoxide, carbon dioxide and sedimented dust in indoor air, of total suspended particulates, heavy metals and of polycyclic aromatic hydrocarbons in indoor and outdoor air. Measurements were taken during winter (heating period) and during summer (non-heating period). Generally, we found higher indoor air pollution in homes with coal burning and open fireplace than in homes with central heating. Especially, the concentrations of carbon monoxide, sedimented dust and of some heavy metals were higher. In one case, we found also high indoor air pollution in a home with central heating. This apartment is on the ground floor of a block of flats, and the central heating system in the basement showed a malfunctioning of the exhaust system.

  10. Testing and analysis of load-side immersed heat exchangers for solar domestic hot water systems

    SciTech Connect

    Farrington, R.B.; Bingham, C.E.

    1987-10-01

    This report describes work to determine the performance of load-side heat exchangers for use in residential solar domestic hot water systems. We measured the performance of four heat exchangers: a smooth coil and a finned coil having heat transfer areas of 2.5 m/sup 2/ (26 ft/sup 2/) and those having areas of 1.7 m/sup 2/ (19 ft/sup 2/). A numerical model using the thermal network program MITAS was constructed, and results were compared to the experimental results. Research showed a smooth coil with only 70% of the surface area of a finned coil performed better than the finned coil. Also, load-side heat exchangers can maintain and enhance stratification in storage tanks, permitting the use of control strategies that take advantage of stratified storage tanks to increase system performance. The analytical model, which agreed reasonably well with the experimental results, was used to vary heat exchanger flow rate and area and initial tank temperature for both a smooth- and a finned-coil heat exchanger. Increasing the heat exchanger flow rate and area results in higher heat transfer rates but not necessarily optimal performance. Lower initial tank temperatures resulted in reduced tank stratification. The smooth heat exchanger outperformed the finned heat exchanger with the same outside surface area. 15 refs., 37 figs., 9 tabs.

  11. The Impact of Winter Heating on Air Pollution in China

    PubMed Central

    Xiao, Qingyang; Ma, Zongwei; Li, Shenshen; Liu, Yang

    2015-01-01

    Fossil-fuel combustion related winter heating has become a major air quality and public health concern in northern China recently. We analyzed the impact of winter heating on aerosol loadings over China using the MODIS-Aqua Collection 6 aerosol product from 2004–2012. Absolute humidity (AH) and planetary boundary layer height (PBL) -adjusted aerosol optical depth (AOD*) was constructed to reflect ground-level PM2.5 concentrations. GIS analysis, standard statistical tests, and statistical modeling indicate that winter heating is an important factor causing increased PM2.5 levels in more than three-quarters of central and eastern China. The heating season AOD* was more than five times higher as the non-heating season AOD*, and the increase in AOD* in the heating areas was greater than in the non-heating areas. Finally, central heating tend to contribute less to air pollution relative to other means of household heating. PMID:25629878

  12. The impact of winter heating on air pollution in China.

    PubMed

    Xiao, Qingyang; Ma, Zongwei; Li, Shenshen; Liu, Yang

    2015-01-01

    Fossil-fuel combustion related winter heating has become a major air quality and public health concern in northern China recently. We analyzed the impact of winter heating on aerosol loadings over China using the MODIS-Aqua Collection 6 aerosol product from 2004-2012. Absolute humidity (AH) and planetary boundary layer height (PBL) -adjusted aerosol optical depth (AOD*) was constructed to reflect ground-level PM2.5 concentrations. GIS analysis, standard statistical tests, and statistical modeling indicate that winter heating is an important factor causing increased PM2.5 levels in more than three-quarters of central and eastern China. The heating season AOD* was more than five times higher as the non-heating season AOD*, and the increase in AOD* in the heating areas was greater than in the non-heating areas. Finally, central heating tend to contribute less to air pollution relative to other means of household heating.

  13. AIR EMISSIONS FROM RESIDENTIAL HEATING: THE WOOD HEATING OPTION PUT INTO ENVIRONMENTAL PERSPECTIVE

    EPA Science Inventory

    The paper compares the national scale (rather than local) air quality impacts of the various residential space heating options. Specifically, it compares the relative contribution of the space heating options to fine particulate emissions, greenhouse gas emissions, and acid preci...

  14. Heating, Ventilation and Air-Conditioning Systems, Part of Indoor Air Quality Design Tools for Schools

    EPA Pesticide Factsheets

    The main purposes of a Heating, Ventilation, and Air-Conditioning system are to help maintain good indoor air quality through adequate ventilation with filtration and provide thermal comfort. HVAC systems are among the largest energy consumers in schools.

  15. Differences between single-side and uniform heating for fusion applications

    SciTech Connect

    Boyd, R.D.; Meng, X.

    1994-12-31

    Many international engineering activities are under way to support fusion reactor implementation for the production of economical energy in the distant future. Among the many key technological issues is the development of plasma-facing components for the International Thermonuclear Experimental Reactor (ITER) and the related engineering design activity. Such components will be exposed to single-side (i.e., internal flow channels will be heated externally from one side only) heat flux ranging from 0.1 to 10.0 MW/m{sup 2} over lengths up to 0.3 m. Although other heat-transfer techniques such as liquid-metal and high-velocity-helium cooling are being seriously considered, subcooled flow boiling (with water) is the leading contender for high heat-flux fusion accommodation (HHFFA). Accordingly, interest must be focused on both the local heat transfer and the critical heat-flux (CHF) phenomena. However, irrespective of the convective fluid used (helium, water, or liquid metal) the advantages and adverse consequences associated with single-side heating must be explored and accommodated in future component designs.

  16. Fast electron transport and induced heating in solid targets from rear-side interferometry imaging.

    PubMed

    Malka, G; Nicolaï, Ph; Brambrink, E; Santos, J J; Aléonard, M M; Amthor, K; Audebert, P; Breil, J; Claverie, G; Gerbaux, M; Gobet, F; Hannachi, F; Méot, V; Morel, P; Scheurer, J N; Tarisien, M; Tikhonchuk, V

    2008-02-01

    Fast adiabatic plasma heating of a thin solid target irradiated by a high intensity laser has been observed by an optical fast interferometry diagnostic. It is driven by the hot electron current induced by the laser plasma interaction at the front side of the target. Radial and longitudinal temperature profiles are calculated to reproduce the observed rear-side plasma expansion. The main parameters of the suprathermal electrons (number, temperature, and divergence) have been deduced from these observations.

  17. Fast electron transport and induced heating in solid targets from rear-side interferometry imaging

    SciTech Connect

    Malka, G.; Aleonard, M. M.; Claverie, G.; Gerbaux, M.; Gobet, F.; Hannachi, F.; Scheurer, J. N.; Tarisien, M.; Brambrink, E.; Audebert, P.; Amthor, K.; Meot, V.; Morel, P.

    2008-02-15

    Fast adiabatic plasma heating of a thin solid target irradiated by a high intensity laser has been observed by an optical fast interferometry diagnostic. It is driven by the hot electron current induced by the laser plasma interaction at the front side of the target. Radial and longitudinal temperature profiles are calculated to reproduce the observed rear-side plasma expansion. The main parameters of the suprathermal electrons (number, temperature, and divergence) have been deduced from these observations.

  18. Thermostructural Behavior of a Hypersonic Aircraft Sandwich Panel Subjected to Heating on One Side

    NASA Technical Reports Server (NTRS)

    Ko, William L.

    1997-01-01

    Thermostructural analysis was performed on a heated titanium honeycomb-core sandwich panel. The sandwich panel was supported at its four edges with spar-like substructures that acted as heat sinks, which are generally not considered in the classical analysis. One side of the panel was heated to high temperature to simulate aerodynamic heating during hypersonic flight. Two types of surface heating were considered: (1) flat-temperature profile, which ignores the effect of edge heat sinks, and (2) dome-shaped-temperature profile, which approximates the actual surface temperature distribution associated with the existence of edge heat sinks. The finite-element method was used to calculate the deformation field and thermal stress distributions in the face sheets and core of the sandwich panel. The detailed thermal stress distributions in the sandwich panel are presented, and critical stress regions are identified. The study shows how the magnitudes of those critical stresses and their locations change with different heating and edge conditions. This technical report presents comprehensive, three-dimensional graphical displays of thermal stress distributions in every part of a titanium honeycomb-core sandwich panel subjected to hypersonic heating on one side. The plots offer quick visualization of the structural response of the panel and are very useful for hot structures designers to identify the critical stress regions.

  19. Testing of heat exchangers in membrane oxygenators using air pressure.

    PubMed

    Hamilton, Carole; Stein, Jutta; Seidler, Rainer; Kind, Robert; Beck, Karin; Tosok, Jürgen; Upterfofel, Jörg

    2006-03-01

    All heat exchangers (HE) in membrane oxygenators are tested by the manufacturer for water leaks during the production phase. However, for safety reasons, it is highly recommended that HEs be tested again before clinical use. The most common method is to attach the heater-cooler to the HE and allow the water to recirculate for at least 10 min, during which time a water leak should be evident. To improve the detection of water leaks, a test was devised using a pressure manometer with an integrated bulb used to pressurize the HE with air. The cardiopulmonary bypass system is set up as per protocol. A pressure manometer adapted to a 1/2" tubing is connected to the water inlet side of the oxygenator. The water outlet side is blocked with a short piece of 1/2" deadend tubing. The HE is pressurized with 250 mmHg for at least 30 sec and observed for any drop. Over the last 2 years, only one oxygenator has been detected with a water leak in which the air-method leaktest was performed. This unit was sent back to the manufacturer who confirmed the failure. Even though the incidence of water leaks is very low, it does occur and it is, therefore, important that all HEs are tested before they are used clinically. This method of using a pressure manometer offers many advantages, as the HE can be tested outside of the operating room (OR), allowing earlier testing of the oxygenator, no water contact is necessary, and it is simple, easy and quick to perform.

  20. Development of low-cost air-to-air heat exchangers. Final report

    SciTech Connect

    Not Available

    1982-11-08

    In summary, comparing the TMG heat exchanger with the well-constructed and high-performance air-to-air heat exchangers assumed for analysis purposes in the LBL studies, the TMG heat exchanger is cost effective for use in low-infiltration houses heated with natural gas, oil and electricity in climates with 4000 or more heating degree (/sup 0/F) days. Experimental and field testing of the final Prototype B air-to-air heat exchanger gave a strong indication that this unit was ready for the market. A Vermont architect ordered 14 units from a pilot production run for a housing project in St. Johnsbury. These units were installed in the late winter of 1981-1982. The units have given excellent service to the point that the architect has considered the use of air-to-air heat exchangers in every subsequent job. Fabrication of the heat exchangers is being done by a small Vermont firm, Echo Fabrications, established primarily to produce air-to-air heat exchangers for the residential and agricultural market. The unit is being marketed under the tradename ECHOCHANGER and is being marketed, distributed and installed by Memphremagog Heat Exchangers, Inc. of Newport, Vermont.

  1. Development of New Air-Cooled Heat Pump Chiller 'Compact Cube'

    NASA Astrophysics Data System (ADS)

    Ookoshi, Yasushi; Ito, Takuya; Yamaguchi, Hiroshi; Kato, Yohei; Ochiai, Yasutaka; Tanaka, Kosuke; Uji, Yoshihiro; Nakayama, Hiroshi

    Further improvement of the performance is requested to air-cooled heat pump chiller from the viewpoint of the global warming prevention. Smaller unit is needed to facilitate the renewal from absorption chiller to air-cooled heat pump chiller. To meet such needs, we developed compact new air-cooled heat pump chiller with high efficiency, 'Compact cube'. The developed machine is side-flow type with U-shaped fin and tube heat exchangers. With this structure, the uniform air velocity, high packed density of the heat exchangers, and the unit miniaturization have been implemented. The refrigeration cycle with two-evaporating temperature has also been implemented. The cooling COP of this cycle is 2% higher compared with conventional one-evaporating temperature cycle because of the rise of average evaporating temperature. In a new model, a new control system, which controls both capacity of compressors and air flow rate corresponding to heat load, has been implemented. As a result, the developed machine achieved IPLV(Integrated Part load Value) to 6.2(MCHV-P1800AE) which is 29% better than the conventional unit.

  2. A solar air collector with integrated latent heat thermal storage

    NASA Astrophysics Data System (ADS)

    Charvat, Pavel; Ostry, Milan; Mauder, Tomas; Klimes, Lubomir

    2012-04-01

    Simulations of the behaviour of a solar air collector with integrated latent heat thermal storage were performed. The model of the collector was created with the use of coupling between TRNSYS 17 and MATLAB. Latent heat storage (Phase Change Material - PCM) was integrated with the solar absorber. The model of the latent heat storage absorber was created in MATLAB and the model of the solar air collector itself was created in TRNSYS with the use of TYPE 56. The model of the latent heat storage absorber allows specification of the PCM properties as well as other parameters. The simulated air collector was the front and back pass collector with the absorber in the middle of the air cavity. Two variants were considered for comparison; the light-weight absorber made of sheet metal and the heat-storage absorber with the PCM. Simulations were performed for the climatic conditions of the Czech Republic (using TMY weather data).

  3. Development of a passive waste heat recovery system. Final report. [Air to air heat exchangers

    SciTech Connect

    Garriss, J.E.

    1984-02-15

    The invention described operates as an effective waste heat reclamation device without the disadvantages of requiring operating power or imposing spatial requirements on equipment location. Electrical power, if used at all, is only for control purposes. The two air streams can be far apart, and may have significantly different elevations. Accordingly, this invention offers some distinct advantages over existing concepts. The first step in this project was to review the basic concept, as described by the patent, for its applicability to industrial waste heat recovery systems. System specifications for a demonstration unit were then developed. A simplified mathematical model was developed to study system performance and size certain equipment items. To facilitate this work, the mathematical model was programmed for use on a Texas Instruments-59 programmable calculator. Following this, specific equipment was specified and layout drawings were prepared. The discussion details these efforts. The equipment was then built and its performance measured.

  4. Ideas and perspectives: Heat stress: more than hot air

    NASA Astrophysics Data System (ADS)

    De Boeck, Hans J.; Van De Velde, Helena; De Groote, Toon; Nijs, Ivan

    2016-10-01

    Climate models project an important increase in the frequency and intensity of heat waves. In gauging the impact on plant responses, much of the focus has been on air temperatures, while a critical analysis of leaf temperatures during heat extremes has not been conducted. Nevertheless, direct physiological consequences from heat depend primarily on leaf rather than on air temperatures. We discuss how the interplay between various environmental variables and the plants' stomatal response affects leaf temperatures and the potential for heat stress by making use of both an energy balance model and field data. The results demonstrate that this interplay between plants and environment can cause leaf temperature to vary substantially at the same air temperature. In general, leaves tended to heat up when radiation was high and when stomates were closed, as expected. But perhaps counterintuitively, high air humidity also raised leaf temperatures, while humid conditions are typically regarded as benign with respect to plant survival since they limit water loss. High wind speeds brought the leaf temperature closer to the air temperature, which can imply either cooling or warming (i.e. abating or reinforcing heat stress) depending on other prevailing conditions. The results thus indicate that heat waves characterized by similar extreme air temperatures may pose little danger under some atmospheric conditions but could be lethal in other cases. The trends illustrated here should give ecologists and agronomists a more informed indication about which circumstances are most conducive to the occurrence of heat stress.

  5. Air-to-water heat pumps for the home

    SciTech Connect

    Bodzin, S.

    1997-07-01

    Heat pump water heaters may be on the rise again. Retrofitters have shied away from this form of water heating due to concerns about cost, moise, efficiency, and maintaenance. Recent advances have overcome some of these problems and are helping the technology find a niche in both hot and cold climates. The topics covered in this article include the following: how heat pump water heaters work; air source from where to where, including air conditioning, heat recovery ventilation, hybrid systems; nuisances; maintenance; costs; to install or not to install; performance: a trick to quantify. 2 figs.

  6. Balloons and Bottles: Activities on Air-Sea Heat Exchange.

    ERIC Educational Resources Information Center

    Murphree, Tom

    1998-01-01

    Presents an activity designed to demonstrate how heating and cooling an air mass affects its temperature, volume, density, and pressure. Illustrates how thermal energy can cause atmospheric motion such as expansion, contraction, and winds. (Author/WRM)

  7. Air Source Cold Climate Heat Pump

    DTIC Science & Technology

    2013-08-01

    The buildings were modified so that one zone used the cold climate heat pump and the other zone used its original modern central HVAC system . Both...been updated with insulation, a sheet metal roof, and a modern central HVAC system . Both buildings had two zones for heating and cooling, which...climate heat pump and the other zone used its original modern central HVAC system . Both zones were instrumented so that energy consumption and

  8. Forced convection heat transfer to air/water vapor mixtures

    NASA Technical Reports Server (NTRS)

    Richards, D. R.; Florschuetz, L. W.

    1986-01-01

    Heat transfer coefficients were measured using both dry air and air/water vapor mixtures in the same forced convection cooling test rig (jet array impingement configurations) with mass ratios of water vapor to air up to 0.23. The primary objective was to verify by direct experiment that selected existing methods for evaluation of viscosity and thermal conductivity of air/water vapor mixtures could be used with confidence to predict heat transfer coefficients for such mixtures using as a basis heat transfer data for dry air only. The property evaluation methods deemed most appropriate require as a basis a measured property value at one mixture composition in addition to the property values for the pure components.

  9. Power module packaging with double sided planar interconnection and heat exchangers

    DOEpatents

    Liang, Zhenxian; Marlino, Laura D.; Ning, Puqi; Wang, Fei

    2015-05-26

    A double sided cooled power module package having a single phase leg topology includes two IGBT and two diode semiconductor dies. Each IGBT die is spaced apart from a diode semiconductor die, forming a switch unit. Two switch units are placed in a planar face-up and face-down configuration. A pair of DBC or other insulated metallic substrates is affixed to each side of the planar phase leg semiconductor dies to form a sandwich structure. Attachment layers are disposed on outer surfaces of the substrates and two heat exchangers are affixed to the substrates by rigid bond layers. The heat exchangers, made of copper or aluminum, have passages for carrying coolant. The power package is manufactured in a two-step assembly and heating process where direct bonds are formed for all bond layers by soldering, sintering, solid diffusion bonding or transient liquid diffusion bonding, with a specially designed jig and fixture.

  10. Forced convection heat transfer to air/water vapor mixtures

    NASA Technical Reports Server (NTRS)

    Richards, D. R.; Florschuetz, L. W.

    1984-01-01

    Heat transfer coefficients were measured using both dry and humid air in the same forced convection cooling scheme and were compared using appropriate nondimensional parameters (Nusselt, Prandtl and Reynolds numbers). A forced convection scheme with a complex flow field, two dimensional arrays of circular jets with crossflow, was utilized with humidity ratios (mass ratio of water vapor to air) up to 0.23. The dynamic viscosity, thermal conductivity and specific heat of air, steam and air/steam mixtures are examined. Methods for determining gaseous mixture properties from the properties of their pure components are reviewed as well as methods for determining these properties with good confidence. The need for more experimentally determined property data for humid air is discussed. It is concluded that dimensionless forms of forced convection heat transfer data and empirical correlations based on measurements with dry air may be applied to conditions involving humid air with the same confidence as for the dry air case itself, provided that the thermophysical properties of the humid air mixtures are known with the same confidence as their dry air counterparts.

  11. Heating, Ventilation, and Air Conditioning Series. Duty Task List.

    ERIC Educational Resources Information Center

    Oklahoma State Dept. of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    This task list is intended for use in planning and/or evaluating a competency-based course in heating, ventilation, and air conditioning. The guide outlines the tasks entailed in eight different duties typically required of employees in the following occupations: residential installer, domestic refrigeration technician, air conditioning and…

  12. Self-defrosting recuperative air-to-air heat exchanger

    DOEpatents

    Drake, Richard L.

    1993-01-01

    A heat exchanger includes a stationary spirally or concentrically wound heat exchanger core with rotating baffles on upper and lower ends thereof. The rotating baffles include rotating inlets and outlets which are in communication with respective fixed inlets and outlets via annuli. The rotation of the baffles causes a concurrent rotation of the temperature distribution within the stationary exchanger core, thereby preventing frost build-up in some applications and preventing the formation of hot spots in other applications.

  13. A fundamentally new approach to air-cooled heat exchangers.

    SciTech Connect

    Koplow, Jeffrey P.

    2010-01-01

    We describe breakthrough results obtained in a feasibility study of a fundamentally new architecture for air-cooled heat exchangers. A longstanding but largely unrealized opportunity in energy efficiency concerns the performance of air-cooled heat exchangers used in air conditioners, heat pumps, and refrigeration equipment. In the case of residential air conditioners, for example, the typical performance of the air cooled heat exchangers used for condensers and evaporators is at best marginal from the standpoint the of achieving maximum the possible coefficient of performance (COP). If by some means it were possible to reduce the thermal resistance of these heat exchangers to a negligible level, a typical energy savings of order 30% could be immediately realized. It has long been known that a several-fold increase in heat exchanger size, in conjunction with the use of much higher volumetric flow rates, provides a straight-forward path to this goal but is not practical from the standpoint of real world applications. The tension in the market place between the need for energy efficiency and logistical considerations such as equipment size, cost and operating noise has resulted in a compromise that is far from ideal. This is the reason that a typical residential air conditioner exhibits significant sensitivity to reductions in fan speed and/or fouling of the heat exchanger surface. The prevailing wisdom is that little can be done to improve this situation; the 'fan-plus-finned-heat-sink' heat exchanger architecture used throughout the energy sector represents an extremely mature technology for which there is little opportunity for further optimization. But the fact remains that conventional fan-plus-finned-heat-sink technology simply doesn't work that well. Their primary physical limitation to performance (i.e. low thermal resistance) is the boundary layer of motionless air that adheres to and envelops all surfaces of the heat exchanger. Within this boundary layer

  14. Thermal fatigue experiment of screw cooling tube under one-sided heating condition

    NASA Astrophysics Data System (ADS)

    Ezato, Koichiro; Suzuki, Satoshi; Sato, Kazuyoshi; Akiba, Masato

    2004-08-01

    This paper presents the results of thermal fatigue experiments of a cooling tube with a helical triangular fin on its inner cooling surface, namely a screw tube. The screw tube is directly machined in a CuCrZr heat sink bar with slits at its heated side. The thermal fatigue experiments are carried out at 20 and 30 MW/m 2. Water leakages from fatigue cracks, found at the slit of the heat sink, occurred at around 4500th and 1400th cycles at 20 and 30 MW/m 2, respectively. These results show good agreement with lifetime predictions using Manson-Coffin's law based on finite element analyses. Fractographic observations show the fatigue cracks starting from the outer heated surface at the slit region of the cooling channel and propagating toward its inner surface.

  15. Simulation of one-sided heating of boiler unit membrane-type water walls

    NASA Astrophysics Data System (ADS)

    Kurepin, M. P.; Serbinovskiy, M. Yu.

    2017-03-01

    This study describes the results of simulation of the temperature field and the stress-strain state of membrane-type gastight water walls of boiler units using the finite element method. The methods of analytical and standard calculation of one-sided heating of fin-tube water walls by a radiative heat flux are analyzed. The methods and software for input data calculation in the finite-element simulation, including thermoelastic moments in welded panels that result from their one-sided heating, are proposed. The method and software modules are used for water wall simulation using ANSYS. The results of simulation of the temperature field, stress field, deformations and displacement of the membrane-type panel for the boiler furnace water wall using the finite-element method, as well as the results of calculation of the panel tube temperature, stresses and deformations using the known methods, are presented. The comparison of the known experimental results on heating and bending by given moments of membrane-type water walls and numerical simulations is performed. It is demonstrated that numerical results agree with high accuracy with the experimental data. The relative temperature difference does not exceed 1%. The relative difference of the experimental fin mutual turning angle caused by one-sided heating by radiative heat flux and the results obtained in the finite element simulation does not exceed 8.5% for nondisplaced fins and 7% for fins with displacement. The same difference for the theoretical results and the simulation using the finite-element method does not exceed 3% and 7.1%, respectively. The proposed method and software modules for simulation of the temperature field and stress-strain state of the water walls are verified and the feasibility of their application in practical design is proven.

  16. Self-defrosting recuperative air-to-air heat exchanger

    DOEpatents

    Drake, R.L.

    1993-12-28

    A heat exchanger is described which includes a stationary spirally or concentrically wound heat exchanger core with rotating baffles on upper and lower ends thereof. The rotating baffles include rotating inlets and outlets which are in communication with respective fixed inlets and outlets via annuli. The rotation of the baffles causes a concurrent rotation of the temperature distribution within the stationary exchanger core, thereby preventing frost build-up in some applications and preventing the formation of hot spots in other applications. 3 figures.

  17. Flat plate solar air heater with latent heat storage

    NASA Astrophysics Data System (ADS)

    Touati, B.; Kerroumi, N.; Virgone, J.

    2017-02-01

    Our work contains two parts, first is an experimental study of the solar air heater with a simple flow and forced convection, we can use thatlaste oneit in many engineering's sectors as solardrying, space heating in particular. The second part is a numerical study with ansys fluent 15 of the storage of part of this solar thermal energy produced,using latent heat by using phase change materials (PCM). In the experimental parts, we realize and tested our solar air heater in URER.MS ADRAR, locate in southwest Algeria. Where we measured the solarradiation, ambient temperature, air flow, thetemperature of the absorber, glasses and the outlet temperature of the solar air heater from the Sunrise to the sunset. In the second part, we added a PCM at outlet part of the solar air heater. This PCM store a part of the energy produced in the day to be used in peak period at evening by using the latent heat where the PCMs present a grateful storagesystem.A numerical study of the fusion or also named the charging of the PCM using ANSYS Fluent 15, this code use the method of enthalpies to solve the fusion and solidification formulations. Furthermore, to improve the conjugate heat transfer between the heat transfer fluid (Air heated in solar plate air heater) and the PCM, we simulate the effect of adding fins to our geometry. Also, four user define are write in C code to describe the thermophysicalpropriety of the PCM, and the inlet temperature of our geometry which is the temperature at the outflow of the solar heater.

  18. Performance evaluation of a selected three-ton air-to-air heat pump in the heating mode

    NASA Astrophysics Data System (ADS)

    Domingorena, A. A.; Ball, S. J.

    1980-01-01

    An air-to-air split system residential heat pump of nominal under laboratory conditions. This was the second of a planned series of experiments to obtain a data base of system and component performance for heat pumps. The system was evaluated under both steady-state and frosting-defrosting conditions; sensitivity of the system performance to variations in the refrigerant charge was measured. From the steady-state tests, the heating capacity and coefficient of performance were computed, and evaluations were made of the performance parameters of the fan and fan motor units, the heat exchangers and refrigerant metering device, and the compressor. System heat losses were analyzed. The frosting-defrosting tests allowed the observation of system and component performance under dynamic conditions, and measurement of performance degradation under frosting conditions.

  19. Experimental and Numerical Analysis of Air Flow, Heat Transfer and Thermal Comfort in Buildings with Different Heating Systems

    NASA Astrophysics Data System (ADS)

    Sabanskis, A.; Virbulis, J.

    2016-04-01

    Monitoring of temperature, humidity and air flow velocity is performed in 5 experimental buildings with the inner size of 3×3×3 m3 located in Riga, Latvia. The buildings are equipped with different heating systems, such as an air-air heat pump, air-water heat pump, capillary heating mat on the ceiling and electric heater. Numerical simulation of air flow and heat transfer by convection, conduction and radiation is carried out using OpenFOAM software and compared with experimental data. Results are analysed regarding the temperature and air flow distribution as well as thermal comfort.

  20. Heating, Ventilating, Air Conditioning and Dehumidifying Systems.

    DTIC Science & Technology

    1980-08-01

    not be connected to other ventilating systems. Duct runs shall be as short as possible to avoid leakage of moisture. I b. Special Considerations. (1...For rectangular duct design, see the SMACNA -Low Pressure Duct Construction Standards. Under jnormal applications, a minimum duct size of 6 by 6 inches...prevent leakage of the moisture-laden discharge air into the intake duct , and the intake and discharge outlets shall be located to prevent any

  1. Intermittent heat instabilities in an air plume

    NASA Astrophysics Data System (ADS)

    Le Mouël, Jean-Louis; Kossobokov, Vladimir G.; Perrier, Frederic; Morat, Pierre

    2016-08-01

    We report the results of heating experiments carried out in an abandoned limestone quarry close to Paris, in an isolated room of a volume of about 400 m3. A heat source made of a metallic resistor of power 100 W was installed on the floor of the room, at distance from the walls. High-quality temperature sensors, with a response time of 20 s, were fixed on a 2 m long bar. In a series of 24 h heating experiments the bar had been set up horizontally at different heights or vertically along the axis of the plume to record changes in temperature distribution with a sampling time varying from 20 to 120 s. When taken in averages over 24 h, the temperatures present the classical shape of steady-state plumes, as described by classical models. On the contrary, the temperature time series show a rich dynamic plume flow with intermittent trains of oscillations, spatially coherent, of large amplitude and a period around 400 s, separated by intervals of relative quiescence whose duration can reach several hours. To our knowledge, no specific theory is available to explain this behavior, which appears to be a chaotic interaction between a turbulent plume and a stratified environment. The observed behavior, with first-order factorization of a smooth spatial function with a global temporal intermittent function, could be a universal feature of some turbulent plumes in geophysical environments.

  2. 21 CFR 211.46 - Ventilation, air filtration, air heating and cooling.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 4 2010-04-01 2010-04-01 false Ventilation, air filtration, air heating and cooling. 211.46 Section 211.46 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) DRUGS: GENERAL CURRENT GOOD MANUFACTURING PRACTICE FOR FINISHED...

  3. Analysis of the performance of an air-water heat pump: Regulation of intrinsic performances

    NASA Astrophysics Data System (ADS)

    Martin-Neuville, H.; Reybillet, M.; Patureau, J. P.

    Improvements for an electrical compressor heat pump of around 12 kW with air as a heat source are examined. To test the heat pump under different weather conditions a test loop has been built. On the condenser side a water circuit with several capacities and heat exchangers simulates the thermal behavior of a 120 sq m dwelling. A commercial domestic heat pump was extensively tested. The instantaneous performance of the heat pump agreed well with the data claimed by the manufacturer. The annual energy saving, however, was significantly less due to the following: (1) loss of efficiency caused by defrosting cycles; (2) loss of efficiency due to inadequate thermal load matching between the heat pump and the house. It was shown that control of the condensing temperature can bring energy savings of 10 percent. This could probably also be realized by load matching with a compressor with a variable speed; and (3) the inefficient operation of components such as the evaporator and the condenser heat exchangers and the expansion valve. Optimization could lead to a considerable improvement. Modifications in the compressor are proposed which may lead to an increase in efficiency to 60 or 70 percent.

  4. Heating and Air Conditioning Specialist. Teacher Edition. Automotive Service Series.

    ERIC Educational Resources Information Center

    Oklahoma State Dept. of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    This instructor's guide contains materials for teaching the heating and air conditioning specialist component of a competency-based instructional program for students preparing for employment in the automotive service trade. It is based on the National Institute of Automotive Service Excellence task lists. The six instructional units presented…

  5. State Skill Standards: Heating, Ventilation, Air Conditioning, and Refrigeration

    ERIC Educational Resources Information Center

    Ball, Larry; Soukup, Dennis

    2006-01-01

    The Department of Education has undertaken an ambitious effort to develop statewide career and technical education skill standards. The standards in this document are for Heating, Ventilation, Air Conditioning and Refrigeration (HVAC&R) programs and are designed to clearly state what the student should know and be able to do upon completion of…

  6. Careers for the 70's in Heating and Air Conditioning

    ERIC Educational Resources Information Center

    Toner, James P.

    1974-01-01

    In a trade encompassing all others in construction, installation foremen for heating/air conditioning firms spend a varied day (repairing a water heater, overseeing installation crews). Decision-makers who must think while using their hands, they rely heavily on preparation in math, mechanical drawing, blueprint reading, physics, and electicity.…

  7. Advanced Print Reading. Heating, Ventilation and Air Conditioning.

    ERIC Educational Resources Information Center

    Oregon State Dept. of Education, Salem.

    This is a workbook for students learning advanced blueprint reading for heating, ventilation, and air conditioning applications. The workbook contains eight units covering the following material: architectural working drawings; architectural symbols and dimensions; basic architectural electrical symbols; wiring symbols; basic piping symbols;…

  8. Air Conditioning, Heating, and Refrigeration: Scope and Sequence.

    ERIC Educational Resources Information Center

    Nashville - Davidson County Metropolitan Public Schools, TN.

    This scope and sequence guide, developed for an air conditioning, heating, and refrigeration vocational education program, represents an initial step in the development of a systemwide articulated curriculum sequence for all vocational programs within the Metropolitan Nashville Public School System. It was developed as a result of needs expressed…

  9. An Analysis of the Air Conditioning, Refrigerating and Heating Occupation.

    ERIC Educational Resources Information Center

    Frass, Melvin R.; Krause, Marvin

    The general purpose of the occupational analysis is to provide workable, basic information dealing with the many and varied duties performed in the air conditioning, refrigerating, and heating occupation. The document opens with a brief introduction followed by a job description. The bulk of the document is presented in table form. Six duties are…

  10. Air Conditioning, Heating, and Refrigeration. Competency-Based Curriculum Manual.

    ERIC Educational Resources Information Center

    Gourley, Frank A., Jr.

    This manual was developed to serve as an aid to administrators and instructors involved with postsecondary air conditioning, heating, and refrigeration programs. The first of six chapters contains general information on program implementation, the curriculum design, facilities and equipment requirements, and textbooks and references. Chapter 2…

  11. Heating, Ventilating, and Air Conditioning. Energy Technology Series.

    ERIC Educational Resources Information Center

    Center for Occupational Research and Development, Inc., Waco, TX.

    This course in heating, ventilating, and air conditioning is one of 16 courses in the Energy Technology Series developed for an Energy Conservation-and-Use Technology curriculum. Intended for use in two-year postsecondary technical institutions to prepare technicians for employment, the courses are also useful in industry for updating employees in…

  12. EnergyPlus Air Source Integrated Heat Pump Model

    SciTech Connect

    Shen, Bo; Adams, Mark B.; New, Joshua Ryan

    2016-03-30

    This report summarizes the development of the EnergyPlus air-source integrated heat pump model. It introduces its physics, sub-models, working modes, and control logic. In addition, inputs and outputs of the new model are described, and input data file (IDF) examples are given.

  13. Heating, Air-Conditioning, and Refrigeration Technician. National Skill Standards.

    ERIC Educational Resources Information Center

    Vocational Technical Education Consortium of States, Decatur, GA.

    This guide contains information on the knowledge and skills identified by industry as essential to the job performance of heating, air-conditioning, and refrigeration technicians. It is intended to assist training providers in public and private institutions, as well as in industry, to develop and implement training that will provide workers with…

  14. Heat-transfer and surface-pressure measurements for the SSME fuel-side turbopump turbine

    NASA Technical Reports Server (NTRS)

    Dunn, Michael G.

    1989-01-01

    Detailed heat flux and surface pressure distribution on the first-stage vane and blade of the Space Shuttle Main Engine fuel side turbopump turbine are examined. The specific turbine being utilized for the study is a combination of actual engine hardware and reproduced hardware consistent with that being used at NASA-Marshall for the initial measurements in their newly constructed blow-down turbine test facility. The facility is of the short duration shock tunnel variety, which permits use of thin film thermometers which are used to measure the surface temperature histories at prescribed locations on the turbine component parts. Heat flux values are then inferred from the temperature histories using standard data reduction procedures. The measurement program is described in detail.

  15. Thermal and economic assessment of hot side sensible heat and cold side phase change storage combination fo absorption solar cooling system

    NASA Astrophysics Data System (ADS)

    Choi, M. K.; Morehouse, J. H.

    An analysis of a solar assisted absorption cooling system which employs a combination of phase change on the cold side and sensible heat storage on the hot side of the cooling machine for small commercial buildings is given. The year-round thermal performance of this system for space cooling were determined by simulation and compared against conventional cooling systems in three geographic locations: Phoenix, Arizona; Miami, Florida and Washington, D.C. The results indicate that the hot-cold storage combination has a considerable amount of energy and economical savings over hot side sensible heat storage. Using the hot-cold storage combination, the optimum collector areas for Washington, D.C., Phoenix and Miami are 355 m squared, 250 m squared and 495 m squared, respectively. Compared against conventional vapor compression chiller, the net solar fractions are 61, 67 and 69 percent, respectively.

  16. Heat tolerance of higher plants cenosis to damaging air temperatures

    NASA Astrophysics Data System (ADS)

    Ushakova, Sofya; Shklavtsova, Ekaterina

    Designing sustained biological-technical life support systems (BTLSS) including higher plants as a part of a photosynthesizing unit, it is important to foresee the multi species cenosis reaction on either stress-factors. Air temperature changing in BTLSS (because of failure of a thermoregulation system) up to the values leading to irreversible damages of photosynthetic processes is one of those factors. However, it is possible to increase, within the certain limits, the plant cenosis tolerance to the unfavorable temperatures’ effect due to the choice of the higher plants possessing resistance both to elevated and to lowered air temperatures. Besides, the plants heat tolerance can be increased when subjecting them during their growing to the hardening off temperatures’ effect. Thus, we have come to the conclusion that it is possible to increase heat tolerance of multi species cenosis under the damaging effect of air temperature of 45 (°) СC.

  17. Temperature distribution of air source heat pump barn with different air flow

    NASA Astrophysics Data System (ADS)

    He, X.; Li, J. C.; Zhao, G. Q.

    2016-08-01

    There are two type of airflow form in tobacco barn, one is air rising, the other is air falling. They are different in the structure layout and working principle, which affect the tobacco barn in the distribution of temperature field and velocity distribution. In order to compare the temperature and air distribution of the two, thereby obtain a tobacco barn whose temperature field and velocity distribution are more uniform. Taking the air source heat pump tobacco barn as the investigated subject and establishing relevant mathematical model, the thermodynamics of the two type of curing barn was analysed and compared based on Fluent. Provide a reasonable evidence for chamber arrangement and selection of outlet for air source heat pump tobacco barn.

  18. Theoretical Study on Dynamic Characteristics of Energy Efficiency Standard Value of Ground Water Heat Pump Air-conditioning System

    NASA Astrophysics Data System (ADS)

    Peng, Yi; Wang, Zhiwei; Zhang, Zhonghe; Cao, Wei; Li, Peng

    The energy efficiency standard value of the ground water heat pump air-conditioning system is the benchmar parameter for energy saving operation and control of the system. According to each loop's process energy consumption of the system, the control equation of energy efficiency standard value of the water source side loop, heat pump unit and user side loop is established respectively. The dynamic characteristics of the standard value variation with the air-conditioning hourly heating and cooling load is revealed, and the energy efficiency standard value of each loop can be also obtained, and the qualitative sensitivity analysis of the dynamic characteristics in each subsystem is carried out. For system energy saving operation and control, the basic data and theoretical guidance can be provided.

  19. Onset of freezing in residential air-to-air heat exchangers

    NASA Astrophysics Data System (ADS)

    Fisk, W. J.; Chant, R.; Archer, K.; Hekmat, D.; Offermann, F.; Pedersen, B.

    1984-11-01

    Mechanical ventilation of residences, with heat recovery in air-to-air heat exchangers, is an increasingly common practice. When this technique of ventilation is used in cold climates, however, freezing can occur in the air-to-air heat exchanger and substantially reduce its performance. A laboratory investigation was conducted to determine the indoor and outdoor environmental conditions that lead to freezing. In a cross flow, counterflow, and enthalpy-type cross flow heat exchanger, respectively, freezing was observed when the inlet temperature of the cold airstream was below -7 to -3 C, approximately -6 C, and -8 to 12 C, for a typical range of indoor humidities. These results are in fair agreement with the theoretical predictions presented and with data from two field studies conducted with similar heat exchangers. Data from a previous laboratory study of a counterflow heat exchanger and tabulated data supplied by ASHRAE, however, indicate that freezing is initiated at significantly lower cold airstream temperatures, particularly when the warm airstream is humid.

  20. Fluid flow and heat transfer in an air-to-water double-pipe heat exchanger

    NASA Astrophysics Data System (ADS)

    Sheikholeslami, M.; Gorji-Bandpy, M.; Ganji, D. D.

    2015-11-01

    This paper reports experimental and numerical investigations on flow and heat transfer in an air-to-water double-pipe heat exchanger. The working fluids are air and water. To achieve fully developed conditions, the heat exchanger was built with additional lengths before and after the test section. The inner and outer tube was made from copper and Plexiglas, respectively. The experiments are conducted in the range of air flow Reynolds number for various cases with different water flow rate and water inlet temperature. Correlations for the Nusselt number and friction factor are presented according to experimental data. Also the commercial code ANSYS 15 is used for numerical simulation. Results show that the Nusselt number is an increasing function of Reynolds number and Prandtl number which are calculated at bulk temperature.

  1. Estimating ocean-air heat fluxes during cold air outbreaks by satellite

    NASA Technical Reports Server (NTRS)

    Chou, S. H.; Atlas, D.

    1981-01-01

    Nomograms of mean column heating due to surface sensible and latent heat fluxes were developed. Mean sensible heating of the cloud free region is related to the cloud free path (CFP, the distance from the shore to the first cloud formation) and the difference between land air and sea surface temperatures, theta sub 1 and theta sub 0, respectively. Mean latent heating is related to the CFP and the difference between land air and sea surface humidities q sub 1 and q sub 0 respectively. Results are also applicable to any path within the cloud free region. Corresponding heat fluxes may be obtained by multiplying the mean heating by the mean wind speed in the boundary layer. The sensible heating estimated by the present method is found to be in good agreement with that computed from the bulk transfer formula. The sensitivity of the solutions to the variations in the initial coastal soundings and large scale subsidence is also investigated. The results are not sensitive to divergence but are affected by the initial lapse rate of potential temperature; the greater the stability, the smaller the heating, other things being equal. Unless one knows the lapse rate at the shore, this requires another independent measurement. For this purpose the downwind slope of the square of the boundary layer height is used, the mean value of which is also directly proportional to the mean sensible heating. The height of the boundary layer should be measurable by future spaceborn lidar systems.

  2. Development of a Variable-Speed Residential Air-Source Integrated Heat Pump

    SciTech Connect

    Rice, C Keith; Shen, Bo; Munk, Jeffrey D; Ally, Moonis Raza; Baxter, Van D

    2014-01-01

    A residential air-source integrated heat pump (AS-IHP) is under development in partnership with a U.S. manufacturer. A nominal 10.6 kW (3-ton) cooling capacity variable-speed unit, the system provides both space conditioning and water heating. This multi-functional unit can provide domestic water heating (DWH) in either full condensing (FC) (dedicated water heating or simultaneous space cooling and water heating) or desuperheating (DS) operation modes. Laboratory test data were used to calibrate a vapor-compression simulation model for each mode of operation. The model was used to optimize the internal control options for efficiency while maintaining acceptable comfort conditions and refrigerant-side pressures and temperatures within allowable operating envelopes. Annual simulations were performed with the AS-IHP installed in a well-insulated house in five U.S. climate zones. The AS-IHP is predicted to use 45 to 60% less energy than a DOE minimum efficiency baseline system while meeting total annual space conditioning and water heating loads. Water heating energy use is lowered by 60 to 75% in cold to warmer climates, respectively. Plans are to field test the unit in Knoxville, TN.

  3. Eddy covariance flux of sulfur dioxide to the sea surface: Air-side resistance to deposition of a highly soluble gas

    NASA Astrophysics Data System (ADS)

    Porter, J.; De Bruyn, W. J.; Miller, S. D.; Saltzman, E. S.

    2014-12-01

    Deposition to the sea surface represents a major atmospheric removal mechanism for sulfur dioxide and many other highly soluble products of tropospheric photochemistry. Such gases include nitric acid, ammonia, organic acids, sulfur dioxide, and highly soluble organic compounds such as methanol and acetone. The deposition of highly soluble gases is controlled by turbulent and diffusive transport on the air side of the air/sea interface. In this study, air/sea fluxes of the soluble gas sulfur dioxide (SO2 ), sensible and latent heat, and momentum were measured using eddy covariance. This was a pilot study carried out in April 2014 on Scripps pier in La Jolla, California, that was designed to assess the potential for measuring SO2 fluxes over the ocean. SO2 was detected using chemical ion mass spectrometry in negative ion mode with a sensitivity of roughly 100 Hz/ppt. The ionization scheme involved addition of ozone to a dried air stream and subsequent conversion of SO2 to the SO5 - ion. The results demonstrate the feasibility of seagoing SO2 flux measurements. Such measurements can be used to constrain the depositional velocities of soluble gases and test models for air-side resistance to air/sea gas transfer.

  4. Recent Research in Compression Refrigeration Cycle Air Source Heat Pumps.

    NASA Astrophysics Data System (ADS)

    Arai, Akira; Senshu, Takao

    The most important theme for heat pump air conditioners is the improvement of energy saving and comfort. Recently, cycle components, especially compressores and heat exchangers have been improved greatly in their performance and efficiency. As for compressors, large progress in their efficiencies have been made by detailed analysises such as mechanical losses and by the development of a new type compression mechanism. As for heat exchangers, various high heat transfer surfaces have been developed together with the improvement of the production technologies for them. Further, the effect of the capacity-modulated cycle is evaluated quantitatively through the improvements of static and transient cycle simulation technologies. And in order to realize this cffect, the electrically driven expansion valves heve been marketed. This review introduces the trends of these energy-saving technologies as well as comfort improvement studies.

  5. Mapping regional distribution of land surface heat fluxes on the southern side of the central Himalayas using TESEBS

    NASA Astrophysics Data System (ADS)

    Amatya, Pukar Man; Ma, Yaoming; Han, Cunbo; Wang, Binbin; Devkota, Lochan Prasad

    2016-05-01

    Recent scientific studies based on large-scale climate model have highlighted the importance of the heat release from the southern side of the Himalayas for the development of South Asian Summer Monsoon. However, studies related to land surface heat fluxes are nonexistent on the southern side. In this study, we test the feasibility of deriving land surface heat fluxes on the central Himalayan region using Topographically Enhanced Surface Energy Balance System (TESEBS), which is forced by MODIS land surface products and Global Land Data Assimilation System (GLDAS) meteorological data. The model results were validated using the first eddy covariance measurement system established in the southern side of the central Himalayas. The derived land surface heat fluxes were close to the field measurements with mean bias of 15.97, -19.89, 8.79, and -20.39 W m-2 for net radiation flux, ground heat flux, sensible heat flux, and latent heat flux respectively. Land surface heat fluxes show strong contrast in pre monsoon, summer monsoon, post monsoon, and winter seasons and different land surface states among the different physiographic regions. In the central Himalayas, the latent heat flux is the dominant consumer of available energy for all physiographic regions except for the High Himalaya where the sensible heat flux is high.

  6. Radiant heat test of Perforated Metal Air Transportable Package (PMATP).

    SciTech Connect

    Gronewald, Patrick James; Oneto, Robert; Mould, John; Pierce, Jim Dwight

    2003-08-01

    A conceptual design for a plutonium air transport package capable of surviving a 'worst case' airplane crash has been developed by Sandia National Laboratories (SNL) for the Japan Nuclear Cycle Development Institute (JNC). A full-scale prototype, designated as the Perforated Metal Air Transport Package (PMATP) was thermally tested in the SNL Radiant Heat Test Facility. This testing, conducted on an undamaged package, simulated a regulation one-hour aviation fuel pool fire test. Finite element thermal predictions compared well with the test results. The package performed as designed, with peak containment package temperatures less than 80 C after exposure to a one-hour test in a 1000 C environment.

  7. Development of solar driven absorption air conditioners and heat pumps

    NASA Astrophysics Data System (ADS)

    Dao, K.; Wahlig, M.; Wali, E.; Rasson, J.; Molishever, E.

    1980-03-01

    The development of absorption refrigeration systems for solar active heating and cooling applications is discussed. The approaches investigated are those using air-cooled condenser-absorber and those leading to coefficient of performances (COP) that increase continuously with heat source temperature. This is primarily an experimental project, with the emphasis on designing, fabricating and testing absorption chillers in operating regimes that are particularly suited for solar energy applications. Its demonstrated that the conventional single-effect ammonia-water absorption cycle can be used (with minor modifications) for solar cooling.

  8. Columbia: The first 5 flights entry heating data series. Volume 5: The side fuselage and payload bay door

    NASA Technical Reports Server (NTRS)

    Williams, S. D.

    1984-01-01

    Entry heating flight data and wind tunnel data on the side fuselage and payload bay door, Z = 400 and 440 trace aft of X/L=0.2, for the first five flights of the Space Shuttle Orbiter are presented. The heating rate data are reviewed in terms of normalized film heat transfer coefficients as a function of angle of attack, Mach number, and normal shock Reynolds number. The surface heatings rates and temperatures were obtained by the JSC NONLIN/INVERSE computer program. Time history plots of the surface heating rates and temperatures are outlined.

  9. The exposure of children to deploying side air bags: an initial field assessment.

    PubMed

    Arbogast, Kristy B; Kallan, Michael J

    2007-01-01

    Tremendous effort has been invested in the laboratory to ensure side air bag (SAB) deployments minimize injury metrics in pediatric anthropometric test devices (ATDs). Little is known, however, about the experience of children exposed to this technology in real world crashes. Therefore, the objective of this study was to determine the prevalence of SAB exposure in children and provide estimates of injury risk among those exposed. This study utilized data from the Partners for Child Passenger Safety study, a large-scale child-focused crash surveillance system, to identify a probability sample of 348 child occupants, age 0-15 years, weighted to represent 6,600 children, in vehicles of model year 1998 and newer, equipped with SABs, in side impact crashes from three large U.S. regions between 1/1/05 and 12/31/06. In the study sample, 27 children per 1000 children in crashes were exposed to a deployed side air bag. Over 75% of these children were seated in the rear seat and 83% were exposed to a head curtain SAB. 65% of those exposed were less than 9 years of age. Of those exposed, 10.6% sustained an AIS2+ injury; all injuries were of the AIS 2 level and limited to the head or upper extremity. This paper provides the first population-based estimates of the exposure of children to SABs. Initial experience suggests that the risk of injury is fairly low with only one in ten sustaining injury - none of which were serious or life threatening. These findings offer assurance that efforts by regulators and the automotive industry to minimize negative consequences from SABs to vulnerable occupants appear to be effective and cause no change in the current recommendation of safe seating for children next to SABs.

  10. Heat-transfer processes in air-cooled engine cylinders

    NASA Technical Reports Server (NTRS)

    Pinkel, Benjamin

    1938-01-01

    From a consideration of heat-transfer theory, semi-empirical expressions are set up for the transfer of heat from the combustion gases to the cylinder of an air-cooled engine and from the cylinder to the cooling air. Simple equations for the average head and barrel temperatures as functions of the important engine and cooling variables are obtained from these expressions. The expressions involve a few empirical constants, which may be readily determined from engine tests. Numerical values for these constants were obtained from single-cylinder engine tests for cylinders of the Pratt & Whitney 1535 and 1340-h engines. The equations provide a means of calculating the effect of the various engine and cooling variables on the cylinder temperatures and also of correlating the results of engine cooling tests. An example is given of the application of the equations to the correlation of cooling-test data obtained in flight.

  11. Advances in shell side condensation for refrigerants

    NASA Astrophysics Data System (ADS)

    Webb, Ralph L.

    The design of shell and tube condensers used in air conditioning and refrigeration applications is discussed. The geometry of interest involves condensation on the shell side of a horizontal tube bundle. Enhanced heat transfer geometries are typically used for condensation on the shell side. The heat transfer is removed by water on the tube side, which typically have tube side enhancement. Single tube and row effect condensation data are presented. Thermal design methods for sizing of the condenser are outlined.

  12. Register Closing Effects on Forced Air Heating System Performance

    SciTech Connect

    Walker, Iain S.

    2003-11-01

    Closing registers in forced air heating systems and leaving some rooms in a house unconditioned has been suggested as a method of quickly saving energy for California consumers. This study combined laboratory measurements of the changes in duct leakage as registers are closed together with modeling techniques to estimate the changes in energy use attributed to closing registers. The results of this study showed that register closing led to increased energy use for a typical California house over a wide combination of climate, duct leakage and number of closed registers. The reduction in building thermal loads due to conditioning only a part of the house was offset by increased duct system losses; mostly due to increased duct leakage. Therefore, the register closing technique is not recommended as a viable energy saving strategy for California houses with ducts located outside conditioned space. The energy penalty associated with the register closing technique was found to be minimized if registers furthest from the air handler are closed first because this tends to only affect the pressures and air leakage for the closed off branch. Closing registers nearer the air handler tends to increase the pressures and air leakage for the whole system. Closing too many registers (more than 60%) is not recommended because the added flow resistance severely restricts the air flow though the system leading to safety concerns. For example, furnaces may operate on the high-limit switch and cooling systems may suffer from frozen coils.

  13. Airshuffler implementation at freezer air outlets for heat transfer enhancement

    NASA Astrophysics Data System (ADS)

    Ćerezci, Gökhan; Darka, Murat; Şenman, Ozan

    2016-06-01

    A study which is composed of computational simulation and experimental validation has been conducted for implementation of small, vane type geometries at freezer air outlets, similar to microvortex generators used in aircraft wings, in order to improve the heat transfer efficiency inside the freezer compartment by decreasing airside thermal resistance and improving the air distribution. Both simulation and experimental validation were performed in a loaded condition which was prepared according to `Household refrigerating appliances - characteristics and test methods - IEC 62552 [1]. Solutions for the incompressible K-epsilon (k-ɛ) turbulence model obtained for Bosch KDN 49 refrigerator freezer both with and without airshufflers at air outlets, which are similar to vane type microvortex generators with different geometric dimensions. The airshuffler dimensions were chosen with design of experiment (DOE) principles for finding the optimum geometry. The best combinations were tested according to cooling rate inside freezer compartment. Results were evaluated for feasibility of implementing of vortex generating surfaces (airshufflers) for cooling appliances.

  14. Hot-gas-side heat transfer characteristics of subscale, plug-nozzle rocket calorimeter chamber

    NASA Technical Reports Server (NTRS)

    Quentmeyer, Richard J.; Roncace, Elizabeth A.

    1993-01-01

    An experimental investigation was conducted to determine the hot-gas-side heat transfer characteristics for a liquid-hydrogen-cooled, subscale, plug-nozzle rocket test apparatus. This apparatus has been used since 1975 to evaluate rocket engine advanced cooling concepts and fabrication techniques, to screen candidate combustion chamber liner materials, and to provide data for model development. In order to obtain the data, a water-cooled calorimeter chamber having the same geometric configuration as the plug-nozzle test apparatus was tested. It also used the same two showerhead injector types that were used on the test apparatus: one having a Rigimesh faceplate and the other having a platelet faceplate. The tests were conducted using liquid oxygen and gaseous hydrogen as the propellants over a mixture ratio range of 5.8 to 6.3 at a nominal chamber pressure of 4.14 MPa abs (600 psia). The two injectors showed similar performance characteristics with the Rigimesh faceplate having a slightly higher average characteristic-exhaust-velocity efficiency of 96 percent versus 94.4 percent for the platelet faceplate. The throat heat flux was 54 MW/m(sup 2) (33 Btu/in.(sup 2)-sec) at the nominal operating condition, which was a chamber pressure of 4.14 MPa abs (600 psia), a hot-gas-side wall temperature of 730 K (1314 R), and a mixture ratio of 6.0. The chamber throat region correlation coefficient C(sub g) for a Nusselt number correlation of the form Nu =C(sub g)Re(sup 0.8)Pr(sup 0.3) averaged 0.023 for the Rigimesh faceplate and 0.026 for the platelet faceplate.

  15. Hot-gas-side heat transfer characteristics of subscale, plug-nozzle rocket calorimeter chamber

    NASA Astrophysics Data System (ADS)

    Quentmeyer, Richard J.; Roncace, Elizabeth A.

    1993-07-01

    An experimental investigation was conducted to determine the hot-gas-side heat transfer characteristics for a liquid-hydrogen-cooled, subscale, plug-nozzle rocket test apparatus. This apparatus has been used since 1975 to evaluate rocket engine advanced cooling concepts and fabrication techniques, to screen candidate combustion chamber liner materials, and to provide data for model development. In order to obtain the data, a water-cooled calorimeter chamber having the same geometric configuration as the plug-nozzle test apparatus was tested. It also used the same two showerhead injector types that were used on the test apparatus: one having a Rigimesh faceplate and the other having a platelet faceplate. The tests were conducted using liquid oxygen and gaseous hydrogen as the propellants over a mixture ratio range of 5.8 to 6.3 at a nominal chamber pressure of 4.14 MPa abs (600 psia). The two injectors showed similar performance characteristics with the Rigimesh faceplate having a slightly higher average characteristic-exhaust-velocity efficiency of 96 percent versus 94.4 percent for the platelet faceplate. The throat heat flux was 54 MW/m(sup 2) (33 Btu/in.(sup 2)-sec) at the nominal operating condition, which was a chamber pressure of 4.14 MPa abs (600 psia), a hot-gas-side wall temperature of 730 K (1314 R), and a mixture ratio of 6.0. The chamber throat region correlation coefficient C(sub g) for a Nusselt number correlation of the form Nu =C(sub g)Re(sup 0.8)Pr(sup 0.3) averaged 0.023 for the Rigimesh faceplate and 0.026 for the platelet faceplate.

  16. 16 CFR Appendix I to Part 305 - Heating Performance and Cost for Central Air Conditioners

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 16 Commercial Practices 1 2013-01-01 2013-01-01 false Heating Performance and Cost for Central Air... RULEâ) Pt. 305, App. I Appendix I to Part 305—Heating Performance and Cost for Central Air Conditioners Manufacturer's rated heating capacity (Btu's/hr.) Range of HSPF's Low High Single Package Units Heat...

  17. 16 CFR Appendix I to Part 305 - Heating Performance and Cost for Central Air Conditioners

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 1 2011-01-01 2011-01-01 false Heating Performance and Cost for Central Air... RULEâ) Pt. 305, App. I Appendix I to Part 305—Heating Performance and Cost for Central Air Conditioners Manufacturer's rated heating capacity (Btu's/hr.) Range of HSPF's Low High Single Package Units Heat...

  18. 16 CFR Appendix I to Part 305 - Heating Performance and Cost for Central Air Conditioners

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 16 Commercial Practices 1 2012-01-01 2012-01-01 false Heating Performance and Cost for Central Air... RULEâ) Pt. 305, App. I Appendix I to Part 305—Heating Performance and Cost for Central Air Conditioners Manufacturer's rated heating capacity (Btu's/hr.) Range of HSPF's Low High Single Package Units Heat...

  19. 16 CFR Appendix I to Part 305 - Heating Performance and Cost for Central Air Conditioners

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Heating Performance and Cost for Central Air... RULEâ) Pt. 305, App. I Appendix I to Part 305—Heating Performance and Cost for Central Air Conditioners Manufacturer's rated heating capacity (Btu's/hr.) Range of HSPF's Low High Single Package Units Heat...

  20. Effects of the arrangement of triangle-winglet-pair vortex generators on heat transfer performance of the shell side of a double-pipe heat exchanger enhanced by helical fins

    NASA Astrophysics Data System (ADS)

    Zhang, Li; Shang, Bojun; Meng, Huibo; Li, Yaxia; Wang, Cuihua; Gong, Bin; Wu, Jianhua

    2017-01-01

    To improve heat transfer performance of the shell side of a double-pipe heat exchanger enhanced by helical fins, triangle-winglet-pair vortex generators (VG) were installed along the centerline of the helical channel with rectangular cross section. The effects of the arrangement of the triangle-winglet-pair VG, such as the geometry, the angle of attack and the quantity on heat transfer performance and pressure drop characteristics have been investigated experimentally to find out the optimal design of the VG. Air was used as working fluid within the range of Re from 680 to 16,000. The results show that, the heat exchange effectiveness of the shell side with VG is 16.6 % higher than that without VG. The vortices and the unsteadiness of the flow introduced by the VG make a great contribution to the increase. Under identical pressure drop condition, the angle of attack of 30° is the best choice compared with 45° and 60°. Under the three constraints, i.e., identical mass flow rate, identical pressure drop and identical pumping power, the largest VG size can achieve the best enhancement effect. Installation of three pairs of VG within one pitch is an optimal design for the shell side used in the present experiments. The enhancement effect of isosceles right triangle is better than that of right triangle in which one acute angle is 30°.

  1. ENERGY STAR Certified Non-AHRI Central Air Conditioner Equipment and Air Source Heat Pump

    EPA Pesticide Factsheets

    Certified models meet all ENERGY STAR requirements as listed in the Version 5.0 ENERGY STAR Program Requirements for Air Source Heat Pump and Central Air Conditioner Equipment that are effective as of September 15, 2015. A detailed listing of key efficiency criteria are available at http://www.energystar.gov/index.cfm?c=airsrc_heat.pr_crit_as_heat_pumps Listed products have been submitted to EPA by ENERGY STAR partners that do not participate in the AHRI certification program. EPA will continue to update this list with products that are certified by EPA-recognized certification bodies other than AHRI. The majority of ENERGY STAR products, certified by AHRI, can be found on the CEE/AHRI Verified Directory at http://www.ceedirectory.org/

  2. Design of Solar Heat Sheet for Air Heaters

    NASA Astrophysics Data System (ADS)

    Priya, S. Shanmuga; Premalatha, M.; Thirunavukkarasu, I.

    2011-12-01

    The technique of harnessing solar energy for drying offers significant potential to dry agricultural products such as food grains, fruits, vegetables and medicinal plants, thereby eliminating many of the problems experienced with open-sun drying and industrial drying, besides saving huge quantities of fossil fuels. A great deal of experimental work over the last few decades has already demonstrated that agricultural products can be satisfactorily dehydrated using solar energy. Various designs of small scale solar dryers have been developed in the recent past, mainly for drying agricultural products. Major problems experienced with solar dryers are their non-reliability as their operation largely depends on local weather conditions. While back-up heaters and hybrid dryers partly solved this issue, difficulties in controlling the drying air temperature and flow rate remains a problem, and affects the quality of the dried product. This study is aimed at eliminating the fluctuations in the quality of hot air supplied by simple solar air heaters used for drying fruits, vegetables and other applications. It is an attempt to analyse the applicability of the combination of an glazed transpired solar collector (tank), thermal storage and a intake fan(suction fan) to achieve a steady supply of air at a different atmospheric temperature and flow rate for drying fruits and vegetables. Development of an efficient, low-cost and reliable air heating system for drying applications is done.

  3. Influence of surface kinematics on air-sea heat flux

    NASA Astrophysics Data System (ADS)

    Veron, Fabrice; Melville, Ken

    2004-11-01

    The top few meters of the oceanic boundary layer play a critical role in the transfers of momentum, gas, mass and heat between the atmosphere and the ocean. These exchanges must necessarily transfer through the surface, and presumably, the rates at which they do are influence by the dynamics of the surface layer. Heat flux in particular is regulated by the thin surface thermal layer which, at most, is only a few millimeter thick. We are specifically interested in the influence of small coherent structures of the surface turbulence on the heat flux. Using active and passive infrared imaging, we measured the evolution the surface velocity and temperature fields over small areas of a few square meters. High-resolution surface Eulerian velocity fields using cross-correlation techniques (PIV) are obtained. Using active marking of the surface with an infrared CO2 laser, we have not only shown that it is possible to directly recover the Langrangian surface velocity, but also, by marking appropriate patterns on the surface we have been able to measure the shear strain, vorticity, and surface divergence. With the penetration depth of infrared radiation at these wavelengths being a few microns, these techniques appear to be quite apt for direct measurements of ocean surface turbulence. We have also found that the flux of heat through the surface appears to be influenced by the surface wave field. We will discuss the results in the context of air sea heat flux and ocean surface turbulence.

  4. Effects of surface roughness on the average heat transfer of an impinging air jet

    SciTech Connect

    Beitelmal, A.H.; Saad, M.A.; Patel, C.D.

    2000-01-01

    Localized cooling by impinging flow has been used in many industrial applications such as in cooling of gas turbine blades and drying processes. Here, effect of surface roughness of a uniformly heated plate on the average heat transfer characteristics of an impinging air jet was experimentally investigated. Two aluminum plates, one with a flat surface and the second with some roughness added to the surface were fabricated. The roughness took the shape of a circular array of protrusions of 0.5mm base and 0.5mm height. A circular Kapton heater of the same diameter as the plates (70mm) supplied the necessary power. The surfaces of the plates were polished to reduce radiation heat losses and the back and sides insulated to reduce conduction heat losses. temperatures were measured over a Reynolds number ranging from 9,600 to 38,500 based on flow rate through a 6.85mm diameter nozzle. The temperature measurements were repeated for nozzle exit-to-plate spacing, z/d, ranging from 1 to 10. The average Nusselt number for both cases was plotted versus the Reynolds number and their functional correlation was determined. The results indicate an increase of up to 6.0% of the average Nusselt number due to surface roughness. This modest increase provides evidence to encourage further investigation and characterization of the surface roughness as a parameter for enhancing heat transfer.

  5. Automotive absorption air conditioner utilizing solar and motor waste heat

    NASA Technical Reports Server (NTRS)

    Popinski, Z. (Inventor)

    1981-01-01

    In combination with the ground vehicles powered by a waste heat generating electric motor, a cooling system including a generator for driving off refrigerant vapor from a strong refrigerant absorbant solution is described. A solar collector, an air-cooled condenser connected with the generator for converting the refrigerant vapor to its liquid state, an air cooled evaporator connected with the condenser for returning the liquid refrigerant to its vapor state, and an absorber is connected to the generator and to the evaporator for dissolving the refrigerant vapor in the weak refrigerant absorbant solution, for providing a strong refrigerant solution. A pump is used to establish a pressurized flow of strong refrigerant absorbant solution from the absorber through the electric motor, and to the collector.

  6. 10 CFR 431.92 - Definitions concerning commercial air conditioners and heat pumps.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... total heating output of a central air-conditioning heat pump during its normal annual usage period for... heat pump (or its produced heating effect, depending on the mode of operation) to its net work input, when both the cooling (or heating) effect and the net work input are expressed in identical units...

  7. Heat waves in Argentina: how unusual was the 2008 heat wave in Buenos Aires?

    NASA Astrophysics Data System (ADS)

    Rusticucci, Matilde; Almeira, Gustavo; Kyselý, Jan; Lhotka, Ondřej

    2014-05-01

    We examine temporal variability of heat waves over Argentina, and estimate recurrence probability of the most severe heat wave in Buenos Aires that occurred in November 2008. The number of days in heat waves per decade was analysed, considering spells of days with maximum temperature above the 90th percentile (MaxTHW), minimum temperature above the 90th percentile (MinTHW), and both maximum and minimum temperatures above the corresponding 90th percentiles (EHW) for the October-March period. Decadal values in Buenos Aires experienced increases in all definitions of heat waves, but at other stations, combinations of different trends or decadal variability resulted in some cases in a decrease of extreme heat waves, as shown in Córdoba (central Argentina) and Las Lomitas (northern Argentina). In the northwestern part of the country, La Quiaca and Tinogasta showed a strong change in the last decade, mainly due to the increment in the persistence of extreme MinTHW but also accompanied by increases in MaxTHW. In general, other stations showed a clear positive trend in MinTHW and decadal variability in MaxTHW, with the largest EHW cases in the last decade. Using simulations with a stochastic first-order autoregressive model (AR1), which reproduces the structure of time series of daily maximum temperatures, we estimated recurrence probability of the longest and most severe heat wave in Buenos Aires (over 1909-2010, according to intensity measured by cumulative excess of daily maximum temperatures above the 90th percentile) that occurred from 3 to 14 November 2008. The results showed that the recurrence probability of such long and severe heat wave is small in the present climate but increases substantially even under a moderate warming trend. The return period of such heat wave is estimated to be in the order of several hundreds years in the present climate while in a climate warmer by 1 °C, the return period declines by an order of magnitude, and in a climate warmer by 4

  8. Statistical analysis of entropy generation in longitudinally finned tube heat exchanger with shell side nanofluid by a single phase approach

    NASA Astrophysics Data System (ADS)

    Konchada, Pavan Kumar; Pv, Vinay; Bhemuni, Varaprasad

    2016-06-01

    The presence of nanoparticles in heat exchangers ascertained increment in heat transfer. The present work focuses on heat transfer in a longitudinal finned tube heat exchanger. Experimentation is done on longitudinal finned tube heat exchanger with pure water as working fluid and the outcome is compared numerically using computational fluid dynamics (CFD) package based on finite volume method for different flow rates. Further 0.8% volume fraction of aluminum oxide (Al2O3) nanofluid is considered on shell side. The simulated nanofluid analysis has been carried out using single phase approach in CFD by updating the user-defined functions and expressions with thermophysical properties of the selected nanofluid. These results are thereafter compared against the results obtained for pure water as shell side fluid. Entropy generated due to heat transfer and fluid flow is calculated for the nanofluid. Analysis of entropy generation is carried out using the Taguchi technique. Analysis of variance (ANOVA) results show that the inlet temperature on shell side has more pronounced effect on entropy generation.

  9. Experimental evaluation of dry/wet air-cooled heat exchangers. Progress report

    SciTech Connect

    Hauser, S.G.; Gruel, R.L.; Huenefeld, J.C.; Eschbach, E.J.; Johnson, B.M.; Kreid, D.K.

    1982-08-01

    The ultimate goal of this project was to contribute to the development of improved cooling facilities for power plants. Specifically, the objective during FY-81 was to experimentally determine the thermal performance and operating characteristics of an air-cooled heat exchanger surface manufactured by the Unifin Company. The performance of the spiral-wound finned tube surface (Unifin) was compared with two inherently different platefin surfaces (one developed by the Trane Co. and the other developed by the HOETERV Institute) which were previously tested as a part of the same continuing program. Under dry operation the heat transfer per unit frontal area per unit inlet temperature difference (ITD) of the Unifin surface was 10% to 20% below that of the other two surfaces at low fan power levels. At high fan power levels, the performances of the Unifin and Trane surfaces were essentially the same, and 25% higher than the HOETERV surface. The design of the Unifin surface caused a significantly larger air-side pressure drop through the heat exchanger both in dry and deluge operation. Generally higher overall heat transfer coefficients were calculated for the Unifin surface under deluged operation. They ranged from 2.0 to 3.5 Btu/hr-ft/sup 2/-/sup 0/F as compared to less than 2.0 Btu hr-ft/sup 2/-/sup 0/F for the Trane and HOETERV surfaces under similar conditions. The heat transfer enhancement due to the evaporative cooling effect was also measureably higher with the Unifin surface as compared to the Trane surface. This can be primarily attributed to the better wetting characteristics of the Unifin surface. If the thermal performance of the surfaces are compared at equal face velocities, the Unifin surface is as much as 35% better. This method of comparison accounts for the wetting characteristics while neglecting the effect of pressure drop. Alternatively the surfaces when compared at equal pressure drop essentially the same thermal performance.

  10. Mathematical modeling of heat exchange between mine air and rock mass during fire

    SciTech Connect

    A.E. Krasnoshtein; B.P. Kazakov; A.V. Shalimov

    2006-05-15

    Solution of problems on heat exchange between ventilating air and rock mass and on gas admixture propagation in mine workings serve as a base for considering changes in heat-gas-air state at a mine after inflammation. The presented mathematical relations allow calculation of a varied velocity and movement direction of air flows, their temperatures and smoking conditions during fire.

  11. 16 CFR Appendix I to Part 305 - Heating Performance and Cost for Central Air Conditioners

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 1 2014-01-01 2014-01-01 false Heating Performance and Cost for Central Air... CONSERVATION ACT (âENERGY LABELING RULEâ) Pt. 305, App. I Appendix I to Part 305—Heating Performance and Cost for Central Air Conditioners Manufacturer's rated heating capacity (Btu's/hr.) Range of HSPF's...

  12. Solar Air Heating Metal Roofing for Reroofing, New Construction, and Retrofit

    DTIC Science & Technology

    2013-06-01

    roof, gym wall and roof before the ESTCP project. ......................... 14 Figure 9. Plan view schematic of solar air heating mechanical systems ...16 Figure 10. Schematic of domestic hot water heating system ................................................. 17...Gaffney Fitness Center, located at Fort Meade, Maryland. The solar air heating metal roofing system uses conventional metal roofing in a traditional

  13. Sampling medium side resistance to uptake of semivolatile organic compounds in passive air samplers.

    PubMed

    Zhang, Xianming; Tsurukawa, Masahiro; Nakano, Takeshi; Lei, Ying D; Wania, Frank

    2011-12-15

    Current theory of the uptake of semivolatile organic compounds in passive air samplers (PAS) assumes uniform chemical distribution and no kinetic resistance within the passive sampling media (PSM) such as polystyrene-divinylbenzene resin (XAD) and polyurethane foam (PUF). However, these assumptions have not been tested experimentally and are challenged by some recently reported observations. To test the assumptions, we performed kinetic uptake experiments indoors using cylindrical PSM that had been concentrically segmented into three layers. Both XAD and PUF were positioned in the same type of sampler housing to eliminate the variation caused by the different housing designs, which enabled us to quantify differences in uptake caused by the properties of the PSM. Duplicated XAD (PUF) samples were retrieved after being deployed for 0, 1 (0.5), 2 (1), 4 (2), 8 (4), 12 (8), and 24 (12) weeks. Upon retrieval, the PSM layers were separated and analyzed individually for PCBs. Passive sampling rates (R) were lower for heavier PCB homologues. Within a homologue group, R for XAD was higher than that for PUF, from which we infer that the design of the "cylindrical can" housing typically used for XAD PAS lowers the R compared to the "double bowl" shelter commonly used for PUF-disk PAS. Outer layers of the PSM sequestered much higher levels of PCBs than inner layers, indicative of a kinetic resistance to chemical transfer within the PSM. The effective diffusivities for chemical transfer within PSM were derived and were found negatively correlated with the partition coefficients between the PSM and air. Based on the results, we conclude that the PSM-side kinetic resistance should be considered when investigating factors influencing R and when deriving R based on the loss of depuration compounds.

  14. Forced convection and flow boiling with and without enhancement devices for top-side-heated horizontal channels

    NASA Astrophysics Data System (ADS)

    Boyd, Ronald D., Sr.; Turknett, Jerry C.

    The effect of enhancement devices on flow boiling heat transfer in coolant channels, which are heated either from the top side or uniformly was studied. Studies are completed of the variations in the local (axial and circumferential) and mean heat transfer coefficients in horizontal, top-heated coolant channels with smooth walls and internal heat transfer enhancement devices. The working fluid is freon-11. The objectives are to: (1) examine the variations in both the mean and local (axial and circumferential) heat transfer coefficients for a circular coolant channel with either smooth walls or with both a twisted tape and spiral finned walls; (2) examine the effect of channel diameter (and the length-to-diameter aspect ratio) variations for the smooth wall channel; and (3) develop and improved data reduction analysis. The case of the top-heated, horizontal flow channel with smooth wall (1.37 cm inside diameter, and 122 cm heated length) was completed. The data were reduced using a preliminary analysis based on the heated hydraulic diameter. Preliminary examination of the local heat transfer coefficient variations indicated that there are significant axial and circumferential variations. However, it appears that the circumferential variation is more significant than the axial ones. In some cases, the circumferential variations were as much as a factor of ten. The axial variations rarely exceeded a factor of three.

  15. Forced convection and flow boiling with and without enhancement devices for top-side-heated horizontal channels

    NASA Technical Reports Server (NTRS)

    Boyd, Ronald D., Sr.; Turknett, Jerry C.

    1989-01-01

    The effect of enhancement devices on flow boiling heat transfer in coolant channels, which are heated either from the top side or uniformly was studied. Studies are completed of the variations in the local (axial and circumferential) and mean heat transfer coefficients in horizontal, top-heated coolant channels with smooth walls and internal heat transfer enhancement devices. The working fluid is freon-11. The objectives are to: (1) examine the variations in both the mean and local (axial and circumferential) heat transfer coefficients for a circular coolant channel with either smooth walls or with both a twisted tape and spiral finned walls; (2) examine the effect of channel diameter (and the length-to-diameter aspect ratio) variations for the smooth wall channel; and (3) develop and improved data reduction analysis. The case of the top-heated, horizontal flow channel with smooth wall (1.37 cm inside diameter, and 122 cm heated length) was completed. The data were reduced using a preliminary analysis based on the heated hydraulic diameter. Preliminary examination of the local heat transfer coefficient variations indicated that there are significant axial and circumferential variations. However, it appears that the circumferential variation is more significant than the axial ones. In some cases, the circumferential variations were as much as a factor of ten. The axial variations rarely exceeded a factor of three.

  16. An analysis of water-to-air heat pump systems for use in government facilities

    NASA Astrophysics Data System (ADS)

    Fretzs, R. G.

    1980-09-01

    Energy consumption is an important issue for government managers. Examined in this thesis is one source of potential energy savings: a method of heating and cooling buildings. Water-to-air heat pumps are analyzed and cost comparisons to conventional heating/cooling systems (gas, fuel oil, electric resistance, and air-to-air heat pumps) are made. The theory of heat pump technology is presented to show how water source heat pumps achieve improved efficiencies over conventional systems. Sources of and disposal of water to support the systems are discussed. Cost comparisons are presented based on computer simulations and fuel cost graphs. Twenty-one percent of U.S. energy consumption is used to heat and cool buildings. Water-to-air heat pumps provide a 30-50 percent savings over other systems. Therefore, a potential 10 percent savings in total energy consumption exists through the use of water source heat pumps.

  17. Airborne Asbestos Exposures from Warm Air Heating Systems in Schools.

    PubMed

    Burdett, Garry J; Dewberry, Kirsty; Staff, James

    2016-01-01

    The aim of this study was to investigate the concentrations of airborne asbestos that can be released into classrooms of schools that have amosite-containing asbestos insulation board (AIB) in the ceiling plenum or other spaces, particularly where there is forced recirculation of air as part of a warm air heating system. Air samples were collected in three or more classrooms at each of three schools, two of which were of CLASP (Consortium of Local Authorities Special Programme) system-built design, during periods when the schools were unoccupied. Two conditions were sampled: (i) the start-up and running of the heating systems with no disturbance (the background) and (ii) running of the heating systems during simulated disturbance. The simulated disturbance was designed to exceed the level of disturbance to the AIB that would routinely take place in an occupied classroom. A total of 60 or more direct impacts that vibrated and/or flexed the encapsulated or enclosed AIB materials were applied over the sampling period. The impacts were carried out at the start of the sampling and repeated at hourly intervals but did not break or damage the AIB. The target air volume for background samples was ~3000 l of air using a static sampler sited either below or ~1 m from the heater outlet. This would allow an analytical sensitivity (AS) of 0.0001 fibres per millilitre (f ml(-1)) to be achieved, which is 1000 times lower than the EU and UK workplace control limit of 0.1 f ml(-1). Samples with lower volumes of air were also collected in case of overloading and for the shorter disturbance sampling times used at one site. The sampler filters were analysed by phase contrast microscopy (PCM) to give a rapid determination of the overall concentration of visible fibres (all types) released and/or by analytical transmission electron microscopy (TEM) to determine the concentration of asbestos fibres. Due to the low number of fibres, results were reported in terms of both the calculated

  18. Airborne Asbestos Exposures from Warm Air Heating Systems in Schools

    PubMed Central

    Burdett, Garry J.; Dewberry, Kirsty; Staff, James

    2016-01-01

    The aim of this study was to investigate the concentrations of airborne asbestos that can be released into classrooms of schools that have amosite-containing asbestos insulation board (AIB) in the ceiling plenum or other spaces, particularly where there is forced recirculation of air as part of a warm air heating system. Air samples were collected in three or more classrooms at each of three schools, two of which were of CLASP (Consortium of Local Authorities Special Programme) system-built design, during periods when the schools were unoccupied. Two conditions were sampled: (i) the start-up and running of the heating systems with no disturbance (the background) and (ii) running of the heating systems during simulated disturbance. The simulated disturbance was designed to exceed the level of disturbance to the AIB that would routinely take place in an occupied classroom. A total of 60 or more direct impacts that vibrated and/or flexed the encapsulated or enclosed AIB materials were applied over the sampling period. The impacts were carried out at the start of the sampling and repeated at hourly intervals but did not break or damage the AIB. The target air volume for background samples was ~3000 l of air using a static sampler sited either below or ~1 m from the heater outlet. This would allow an analytical sensitivity (AS) of 0.0001 fibres per millilitre (f ml−1) to be achieved, which is 1000 times lower than the EU and UK workplace control limit of 0.1 f ml−1. Samples with lower volumes of air were also collected in case of overloading and for the shorter disturbance sampling times used at one site. The sampler filters were analysed by phase contrast microscopy (PCM) to give a rapid determination of the overall concentration of visible fibres (all types) released and/or by analytical transmission electron microscopy (TEM) to determine the concentration of asbestos fibres. Due to the low number of fibres, results were reported in terms of both the calculated

  19. On the different regimes of gas heating in air plasmas

    NASA Astrophysics Data System (ADS)

    Pintassilgo, Carlos D.; Guerra, Vasco

    2015-10-01

    Simulations of the gas temperature in air (N2-20%O2) plasma discharges are presented for different values of the reduced electric field, E/N g, electron density n e, pressure and tube radius. This study is based on the solutions to the time-dependent gas thermal balance in a cylindrical geometry coupled to the electron, vibrational and chemical kinetics, for E/{{N}\\text{g}}=50 and 100 Td (1 Td = 10-17 V cm2), 109  ⩽  n e  ⩽  1011 cm-3, pressure in the range 1-20 Torr, and also considering different tube radius, 0.5, 1 and 1.5 cm. The competing role of different gas heating mechanisms is discussed in detail within the time range 0.01-100 ms. For times below 1 ms, gas heating occurs from O2 dissociation by electron impact through pre-dissociative excited states, e + O2  →  e + \\text{O}2*   →  e + 2O(3P) and …  →  e + O(3P) + O(1D), as well as through the quenching of N2 electronically excited states by O2. For longer times, simulation results show that gas heating comes from processes N(4S) + NO(X)  →  N2(X, v ~ 3) + O, N2(A) + O  →  NO(X) + N(2D), V-T N2-O collisions and the recombination of oxygen atoms at the wall. Depending on the given E/N g and n e values, each one of these processes can be an important gas-heating channel. The contribution of V-T N2-O exchanges to gas heating is important in the analysis of the gas temperature for different pressures and values of the tube radius. A global picture of these effects is given by the study of the fraction of the discharge power spent on gas heating, which is always ~15%. The values for the fractional power transferred to gas heating from vibrational and electronic excitation are also presented and discussed.

  20. Field evaluation of advanced controls for the retrofit of packaged air conditioners and heat pumps

    SciTech Connect

    Wang, Weimin; Katipamula, Srinivas; Ngo, Hung; Underhill, Ronald M.; Taasevigen, Danny J.; Lutes, Robert G.

    2015-09-01

    This paper documents the magnitude of energy savings achievable in the field by retrofitting existing packaged rooftop units (RTUs) with advanced control strategies not ordinarily used for RTUs. A total of 66 RTUs on 8 different buildings were retrofitted with a commercially available advanced controller for improving RTU operational efficiency. The controller features enhanced air-side economizer control, multi-speed fan control, and demand controlled ventilation. Of the 66 RTUs, 18 are packaged heat pumps and the rest are packaged air conditioners with gas heat. The eight buildings cover four building types and four climate conditions. Based on the data collected for about a whole year, the advanced controller reduced the normalized annual RTU energy consumption between 22% and 90%, with an average of 57% for all RTUs. The average fractional savings uncertainty was 12% at 95% confidence level. Normalized annual electricity savings were in the range between 0.47 kWh/h (kWh per hour of RTU operation) and 7.21 kWh/h, with an average of 2.39 kWh/h. RTUs greater than 53 kW and runtime greater than 14 hours per day had payback periods less than 3 years even at $0.05/kWh.

  1. 10 CFR 431.92 - Definitions concerning commercial air conditioners and heat pumps.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ..., and functional (or hydraulic) characteristics that affect energy consumption, energy efficiency, water..., steam, or electricity. Packaged terminal heat pump means a packaged terminal air conditioner...

  2. Mathematical and experimental investigation of heat control and power increase in air-cooled aircraft engines

    NASA Technical Reports Server (NTRS)

    Gosslau, F

    1929-01-01

    In order to understand the numerical relations between the air velocity, temperature of the cylinder walls, heat dissipation, cylinder dimensions and type of construction an experimental plant was installed in the Siemens and Halske laboratory. The experimental cylinder was exposed to the air stream of a wind tunnel. The compression chamber was heated by an electrically heated oil bath kept constantly in motion by a stirrer. The wall temperatures were measured by thermocouples. The air stream was produced a seven-watt blower. The air flowed through a current rectifier (honeycomb), diffuser, air chamber with quieting sieves and a nozzle.

  3. Experimental investigation on the photovoltaic-thermal solar heat pump air-conditioning system on water-heating mode

    SciTech Connect

    Fang, Guiyin; Hu, Hainan; Liu, Xu

    2010-09-15

    An experimental study on operation performance of photovoltaic-thermal solar heat pump air-conditioning system was conducted in this paper. The experimental system of photovoltaic-thermal solar heat pump air-conditioning system was set up. The performance parameters such as the evaporation pressure, the condensation pressure and the coefficient of performance (COP) of heat pump air-conditioning system, the water temperature and receiving heat capacity in water heater, the photovoltaic (PV) module temperature and the photovoltaic efficiency were investigated. The experimental results show that the mean photovoltaic efficiency of photovoltaic-thermal (PV/T) solar heat pump air-conditioning system reaches 10.4%, and can improve 23.8% in comparison with that of the conventional photovoltaic module, the mean COP of heat pump air-conditioning system may attain 2.88 and the water temperature in water heater can increase to 42 C. These results indicate that the photovoltaic-thermal solar heat pump air-conditioning system has better performances and can stably work. (author)

  4. Experimental measurements and analytical analysis related to gas turbine heat transfer. Part 1: Time-averaged heat-flux and surface-pressure measurements on the vanes and blades of the SSME fuel-side turbine and comparison with prediction. Part 2: Phase-resolved surface-pressure and heat-flux measurements on the first blade of the SSME fuel-side turbine

    NASA Astrophysics Data System (ADS)

    1994-05-01

    Time averaged Stanton number and surface-pressure distributions are reported for the first-stage vane row, the first stage blade row, and the second stage vane row of the Rocketdyne Space Shuttle Main Engine two-stage fuel-side turbine. Unsteady pressure envelope measurements for the first blade are also reported. These measurements were made at 10 percent, 50 percent, and 90 percent span on both the pressure and suction surfaces of the first stage components. Additional Stanton number measurements were made on the first stage blade platform blade tip, and shroud, and at 50 percent span on the second vane. A shock tube was used as a short duration source of heated and pressurized air to which the turbine was subjected. Platinum thin-film heat flux gages were used to obtain the heat flux measurements, while miniature silicon-diaphragm flush-mounted pressure transducers were used to obtain the pressure measurements. The first stage vane Stanton number distributions are compared with predictions obtained using a version of STAN5 and a quasi-3D Navier-Stokes solution. This same quasi-3D N-S code was also used to obtain predictions for the first blade and the second vane.

  5. Experimental measurements and analytical analysis related to gas turbine heat transfer. Part 1: Time-averaged heat-flux and surface-pressure measurements on the vanes and blades of the SSME fuel-side turbine and comparison with prediction. Part 2: Phase-resolved surface-pressure and heat-flux measurements on the first blade of the SSME fuel-side turbine

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Time averaged Stanton number and surface-pressure distributions are reported for the first-stage vane row, the first stage blade row, and the second stage vane row of the Rocketdyne Space Shuttle Main Engine two-stage fuel-side turbine. Unsteady pressure envelope measurements for the first blade are also reported. These measurements were made at 10 percent, 50 percent, and 90 percent span on both the pressure and suction surfaces of the first stage components. Additional Stanton number measurements were made on the first stage blade platform blade tip, and shroud, and at 50 percent span on the second vane. A shock tube was used as a short duration source of heated and pressurized air to which the turbine was subjected. Platinum thin-film heat flux gages were used to obtain the heat flux measurements, while miniature silicon-diaphragm flush-mounted pressure transducers were used to obtain the pressure measurements. The first stage vane Stanton number distributions are compared with predictions obtained using a version of STAN5 and a quasi-3D Navier-Stokes solution. This same quasi-3D N-S code was also used to obtain predictions for the first blade and the second vane.

  6. Heat transfer analysis in a two-side heated smooth square vertical channel with adverse and favorable mixed convection

    SciTech Connect

    Dutta, S.; Zhang, X.; Khan, J.A.; Bell, D.

    1997-07-01

    Experimental heat transfer measurements and analysis for mixed convection in a vertical square channel are presented. The flow direction is changed with respect to the earth's gravity field by selectively opening and closing the flow control valves. Desired flow directions are selected such that buoyancy assists or opposes the bulk flow direction pressure gradient. The heating condition is asymmetric. Most previous experiments used symmetrically heated circular tubes. Present configuration shows significant increase in the Nusselt number in both assisted and opposed flow conditions. In general, opposed flow shows higher heat transfer coefficients. Unlike symmetric heating conditions, Nusselt number ratio is observed to be increasing with increasing Gr/Re or Gr/Re{sup 2} ratios for both assisted and opposed flow conditions.

  7. Fluidized bed heat exchanger with water cooled air distributor and dust hopper

    DOEpatents

    Jukkola, Walfred W.; Leon, Albert M.; Van Dyk, Jr., Garritt C.; McCoy, Daniel E.; Fisher, Barry L.; Saiers, Timothy L.; Karstetter, Marlin E.

    1981-11-24

    A fluidized bed heat exchanger is provided in which air is passed through a bed of particulate material containing fuel. A steam-water natural circulation system is provided for heat exchange and the housing of the heat exchanger has a water-wall type construction. Vertical in-bed heat exchange tubes are provided and the air distributor is water-cooled. A water-cooled dust hopper is provided in the housing to collect particulates from the combustion gases and separate the combustion zone from a volume within said housing in which convection heat exchange tubes are provided to extract heat from the exiting combustion gases.

  8. The solar assisted air-source heat pump system, part 1

    NASA Astrophysics Data System (ADS)

    Hino, T.

    1980-11-01

    A new heat pump heating and air conditioning system was proposed and tested. It features the effective utilization of climatic conditions as its heat sources and sinks, to improve the thermodynamic efficiencies. Reduced electricity consumption, utility load leveling and the least environmental pollutions are expected. The outdoor unit of this heat pump is composed of aluminum panels that are painted black to enhance the radiative heat exchange and fixed almost perpendicularly to improve the natural convective heat transfer with air. The working fluid is halocarbon and commonly used in the heat transfer circuits and the refrigeration cycle. In the heating cycle, the liquid refrigerant evaporates in the passages of the panel. When insolation to the panels is sufficient to meet the heat pump evaporator capacity, the panel temperature will be almost the same as the outdoor air temperature. Thus little convective heat loss to the surrounding air occurs. As the insolation decreases the panel temperature falls several degrees below the outdoor air to absorb heat out of the air until the equilibrium condition is reached.

  9. Natural convection in a flexible sided triangular cavity with internal heat generation under the effect of inclined magnetic field

    NASA Astrophysics Data System (ADS)

    Selimefendigil, Fatih; Öztop, Hakan F.

    2016-11-01

    In this numerical study, magnetohydrodynamics natural convection in a flexible sided triangular cavity with internal heat generation is investigated. The inclined wall of the cavity is cooled and flexible while the left vertical wall is partially heated. Galerkin weighted residual finite element method is used to solve the governing equations. The effects of pertinent parameters such as external Rayleigh number (between 104 and 106), internal Rayleigh number (between 104 and 107), elastic modulus of flexible wall (between 500 and 105), Hartmann number (between 0 and 40) and inclination angle of the magnetic field (between 0° and 90°) on the fluid flow and heat transfer characteristics were numerically investigated. It was observed local and averaged Nusselt number enhance with external Rayleigh number but in the vicinity of the upper location of the heater local heat transfer deteriorates due to the inclined wall deformation with increasing external Rayleigh number. Heat transfer reduces with internal Rayleigh number and Hartmann number. Averaged heat transfer decreases 13.25% when internal Rayleigh number is increased from 104 to 107 and decreases 40.56% when Hartmann number is increased from 0 to 10. The reduction in the convection with magnetic field is effective for higher values of external Rayleigh numbers and averaged heat transfer increases with magnetic field inclination angle.

  10. A Comparison of the Tube-Side Performance of Enhanced Heat Transfer Tubing for Naval Condensers.

    DTIC Science & Technology

    1982-12-01

    enhanced heat transfer in internally ribbed and spirally corrugated tubes is compiled and examined to determine the effects of the geometric characteristics...coefficient for single-start and multiple- start spirally corrugated tubes based on the law of the wall similarity analysis and a heat transfer...research in the area of enhanced heat transfer in internally ribbed and spirally corrugated tubes is compiled and examined to deter- mine the effects of the

  11. Energy-efficient heat recovery systems for air conditioning of indoor swimming pools

    SciTech Connect

    Elsayed, M.M.; El-Refaee, M.M.; Borhan, Y.A.

    1997-12-31

    Analysis of a conventional air-conditioning system for indoor swimming pools during the summer season is presented. The analysis showed that the cooling load is characterized by a large latent heat fraction. As a result, a reheating process must be used downstream of the cooling coil to achieve the proper design comfort condition in the pool area. This, in turn, increases the energy requirement per unit cooling load of the pool. Two heat recovery systems are proposed to reduce this energy. In the first system, ambient air is used for the reheating process in an air-to-air heat exchanger. In the second system, mixed air--recirculated and ambient air--is used for the reheating process. Heat recovery efficiency is defined as an index of the energy savings resulting from the use of the heat recovery system compared to that of a conventional air-conditioning system. At a wide range of ambient conditions it is found that the energy savings could be up to 70% of the energy required to operate a conventional air-conditioning system. A parametric study was carried out to size the air-to-air heat exchanger associated with these heat recovery systems, and the results showed that a heat exchanger having an effectiveness of 0.5 would give satisfactory results. The proposed heat recovery systems are also compared to the case of reheating using the heat rejection from the condenser of the refrigeration machine. The comparison showed that the proposed systems save more energy than reheating using the condenser heat. A typical case study is given to demonstrate the savings in energy consumption when these systems are used.

  12. Temperature and Humidity Independent Control Research on Ground Source Heat Pump Air Conditioning System

    NASA Astrophysics Data System (ADS)

    Chen, G.; Wang, L. L.

    Taking green demonstration center building air conditioning system as an example, this paper presents the temperature and humidity independent control system combined with ground source heat pump system, emphasis on the design of dry terminal device system, fresh air system and ground source heat pump system.

  13. 16 CFR 305.12 - Labeling for central air conditioners, heat pumps, and furnaces.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... pumps, and furnaces. 305.12 Section 305.12 Commercial Practices FEDERAL TRADE COMMISSION REGULATIONS... air conditioners, heat pumps, and furnaces. (a) Layout. All energy labels for central air conditioners, heat pumps, and furnaces (including boilers) shall use one size, similar colors, and typefaces...

  14. Criterion-Referenced Test (CRT) Items for Air Conditioning, Heating and Refrigeration.

    ERIC Educational Resources Information Center

    Davis, Diane, Ed.

    These criterion-referenced test (CRT) items for air conditioning, heating, and refrigeration are keyed to the Missouri Air Conditioning, Heating, and Refrigeration Competency Profile. The items are designed to work with both the Vocational Instructional Management System and Vocational Administrative Management System. For word processing and…

  15. Air Conditioning, Heating, and Ventilating: Construction, Supervision, and Inspection. Course of Study.

    ERIC Educational Resources Information Center

    Messer, John D.

    This course of study on air conditioning, heating, and ventilating is part of a construction, supervision, and inspection series, which provides instructional materials for community or junior college technical courses in the inspection program. Material covered pertains to: piping and piping systems; air movers; boilers; heat exchangers; cooling…

  16. 10 CFR 431.92 - Definitions concerning commercial air conditioners and heat pumps.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... water, or gas, but may not include reverse cycle refrigeration as a heating means. Single package... measurement. Commercial package air-conditioning and heating equipment means air-cooled, water-cooled, evaporatively-cooled, or water source (not including ground water source) electrically operated, unitary...

  17. Study of Ram-air Heat Exchangers for Reducing Turbine Cooling-air Temperature of a Supersonic Aircraft Turbojet Engine

    NASA Technical Reports Server (NTRS)

    Diaguila, Anthony J; Livingood, John N B; Eckert, Ernst R G

    1956-01-01

    The sizes and weights of the cores of heat exchangers were determined analytically for possible application for reducing turbine cooling-air temperatures of an engine designed for a Mach number of 2.5 and an altitude The sizes and weights of the cores of heat exchangers were determined analytically for possible application for reducing turbine cooling-air temperatures of an engine designed for a Mach number of 2.5 and an altitude of 70,000 feet. A compressor-bleed-air weight flow of 2.7 pounds per second was assumed for the coolant; ram air was considered as the other fluid. Pressure drops and inlet states of both fluids were prescribed, and ranges of compressor-bleed-air temperature reductions and of the ratio of compressor-bleed to ram-air weight flows were considered.

  18. On the Influence of a Fuel Side Heat-Loss (Soot) Layer on a Planar Diffusion Flame

    NASA Technical Reports Server (NTRS)

    Wichman, Indrek S.

    1994-01-01

    A model of the response of a diffusion flame (DF) to an adjacent heat loss or 'soot' layer on the fuel side is investigated. The thermal influence of the 'soot' or heat-loss layer on the DF occurs through the enthalpy sink it creates. A sink distribution in mixture-fraction space is employed to examine possible DF extinction. It is found that (1) the enthalpy sink (or soot layer) must touch the DF for radiation-induced quenching to occur; and (2) for fuel-rich conditions extinction is possible only for a progressively narrower range of values ot the characteristic heat-loss parameter, N(sub R)(Delta Z(sub R)) Various interpretations ot the model are discussed. An attempt is made to place this work into the context created by previous experimental and computational studies.

  19. Laboratory determination of frosting and defrosting losses for a high-efficiency air-source heat pump

    SciTech Connect

    Miller, W.A.; Ellison, R.D.

    1981-01-01

    Tests were performed to detail system and component performance data, to quantify the dynamic losses, and to seek and evaluate methods for reducing these losses. A high efficiency split-system heat pump was installed in two separate air loops, with one loop housing the indoor unit and the other housing the outdoor unit. Calculations of the heat pump's performance based on air-side measurements were within 3% of that based on refrigerant side measurements. Refrigerant flow rate was measured using a turbine flow meter. Refrigerant temperatures and pressures were measured with thermocouples and pressure transducers connected at various strategic locations in the refrigeration circuit. Electric power consumption for all motors was measured with Thermal-watt converters. Performance of the heat pump was measured under steady-state, dehumidification, and frosting-defrosting conditions with major emphasis placed on the dynamic frosting operation of the system. The study encompassed an evaluation of the system and component performance for ambient temperature levels of 8.3, 4.4, 1.7, -1.1 and -8.3/sup 0/C and for discrete humidity levels ranging from 50 to 90%.

  20. The Impact of the Ocean Thermal Skin Layer on Air-Sea Interfacial Heat Fluxes

    NASA Astrophysics Data System (ADS)

    Minnett, P. J.; Wong, E.

    2015-12-01

    The upper ocean heat content has been observed to be increasing over the past few decades much of which has been attributed to anthropogenic effects resulting in an increase in greenhouse gases thereby increasing the amounts of incoming longwave (LWin) radiation impinging onto the ocean's surface. However, the penetration depth of LWin extends to micrometer scales, where the ocean's thermal skin layer (TSL) exists, and does not directly heat the upper few meters of the ocean thereby raising the conundrum of how does the upper ocean warm with increasing levels of infrared (IR) radiation. The TSL consists of a strong temperature gradient on the aqueous side of the interface that sustains the upward heat flux by molecular conduction. As such, we hypothesize the heat lost through the air-sea interface which is controlled by the TSL, modulates the amount of heat stored in the upper few meters of the ocean. An analysis of properties of the retrieved TSL profiles from a shipboard IR spectrometer with heat fluxes (specifically LWin) and wind speeds from two cruises limited to night-time data are presented. We also show a comparison between these properties with current published viscous layer models. The results indicate that the data have an inherent wind speed dependence with net flux thereby requiring a segregation of the data into wind speed bins to acknowledge the effects of wind-driven shear in the analysis. The temperature differences derived from the models indicates that at low wind speeds (<2 m/s), where wind-driven shear effects are negligible and buoyancy effects dominate, the TSL profile's gradient is decreasing with increased LWin which leads to a lowered net heat flux and is in agreement with our hypothesis. However our field results show an opposite effect (higher gradient at higher LWin) which is believed to be due to the formation of a thicker TSL at low winds. The presence of a thicker TSL suggests that more of the vertical temperature gradient lies

  1. Measured Performance of a Low Temperature Air Source Heat Pump

    SciTech Connect

    R.K. Johnson

    2013-09-01

    A 4-ton Low Temperature Heat Pump (LTHP) manufactured by Hallowell International was installed in a residence near New Haven, Connecticut and monitored over two winters of operation. After attending to some significant service issues, the heat pump operated as designed. This report should be considered a review of the dual compressor “boosted heat pump” technology. The Low Temperature Heat Pump system operates with four increasing levels of capacity (heat output) as the outdoor temperature drops.

  2. Vehicle cabin cooling system for capturing and exhausting heated boundary layer air from inner surfaces of solar heated windows

    DOEpatents

    Farrington, Robert B.; Anderson, Ren

    2001-01-01

    The cabin cooling system includes a cooling duct positioned proximate and above upper edges of one or more windows of a vehicle to exhaust hot air as the air is heated by inner surfaces of the windows and forms thin boundary layers of heated air adjacent the heated windows. The cabin cooling system includes at least one fan to draw the hot air into the cooling duct at a flow rate that captures the hot air in the boundary layer without capturing a significant portion of the cooler cabin interior air and to discharge the hot air at a point outside the vehicle cabin, such as the vehicle trunk. In a preferred embodiment, the cooling duct has a cross-sectional area that gradually increases from a distal point to a proximal point to the fan inlet to develop a substantially uniform pressure drop along the length of the cooling duct. Correspondingly, this cross-sectional configuration develops a uniform suction pressure and uniform flow rate at the upper edge of the window to capture the hot air in the boundary layer adjacent each window.

  3. Experimental investigation on the heat transfer characteristics and flow pattern in vertical narrow channels heated from one side

    NASA Astrophysics Data System (ADS)

    Huang, Lihao; Li, Gang; Tao, Leren

    2016-07-01

    Experimental investigation for the flow boiling of water in a vertical rectangular channel was conducted to reveal the boiling heat transfer mechanism and flow patterns map aspects. The onset of nucleate boiling went upward with the increasing of the working fluid mass flow rate or the decreasing of the inlet working fluid temperature. As the vapour quality was increased, the local heat transfer coefficient increased first, then decreased, followed by various flow patterns. The test data from other researchers had a similar pattern transition for the bubble-slug flow and the slug-annular flow. Flow pattern transition model analysis was performed to make the comparison with current test data. The slug-annular and churn-annular transition models showed a close trend with current data except that the vapor phase superficial velocity of flow pattern transition was much higher than that of experimental data.

  4. Reduced heat stress in offices in the tropics using solar powered drying of the supply air.

    PubMed

    Gunnarsen, L; Santos, A M B

    2002-12-01

    Many solutions to indoor climate problems known from developed countries may have prohibitive installation and running costs in developing countries. The purpose was to develop a low-cost solution to heat stress in a hot and humid environment based on solar powered drying of supply air. Dry supply air may facilitate personal cooling by increased evaporation of sweat. Heat acclimatized people with efficient sweating may in particular benefit from this cooling. A prototype solar powered supply system for dried-only air was made. Air from the system was mixed with room air, heated to six different combinations of temperature and humidity and led to Personal Units for Ventilation and Cooling (PUVAC) in six cubicles simulating office workplaces. A total of 123 heat acclimatized subjects were exposed 45 min in each of the cubicles. A model for the combined effect of operative temperature of room, moisture content of room air, temperature of supply air and moisture content of supply air was developed based on the experiments. Reduction of moisture content in the supply air by 1.6 g/kg had the same effect as lowering the operative temperature by 1 degree C. The solar-powered system for supplying dry air is a low-cost alternative to traditional air conditioning in hot and humid regions.

  5. [Transfer of organisms during exchange of heat and moisture in air conditioning installations (author's transl)].

    PubMed

    Beckert, J; Sinner, G

    1975-07-01

    With the exhaust air from ventilation and air conditioning installations escaping into the open, the heat content is also lost which fresh air from outside obtains at considerable expense of energy and technical equipment. The heat content, on the other hand, consists of about equal proportions of sensible heat and latent heat which is associated with the moisture content of the air. In order to regain the heat content of the escaping air so as to be able to use it again - and this is becoming increasingly important with rising energy costs - heat exchangers are necessary which remove the heat content from the exhaust air and transfer it to the fresh air from outside. With the high proportion of latent heat, this energy exchange is only effective if the latent heat can also be regained. For this purpose it is essential to have exchange surfaces which store and transfer both heat and moisture. To achieve this they must come into contact with the exhaust air stream and the fresh air stream alternately. Technically, this is done in a simple way by resolving rotor-like storage material. But a rigid separation of the air streams is no longer possible. Even if it is known that there are very highly developed sealing elements between the fixed and moving parts, the question whether particles from the exhaust air can get into the newly introduced outside air through the rotating storage material still gains in importance in certain types of usuage. For example, this is of importance for hospitals, especially in the operation areas in which air conditioning is desirable for 24 hours daily on hygienic grounds, but also in schools and offices where the present normal practice, for economic reasons, of recirculating air is to be avoided to stop the transference of infections pathogens and odours. In various places, experiments have been carried out earlier with heat exchangers consisting of asbestos board and with rotating storage material coated with lithium chloride and a

  6. Cold energy release characteristics of an ice/air direct contact heat exchanger

    SciTech Connect

    Ohira, Akiyoshi; Yanadori, Michio; Iwabuchi, Kunihiko; Kimura, Toshikatsu; Tsubota, Yuji

    1998-12-31

    This paper deals with the cold energy release characteristics of an ice/air direct contact heat exchanger in a refined cold energy conveyance system. Characteristics of the outlet temperature, the humidity, and time history of released heat are examined when the initial height of the ice-cube-packed bed in the heat exchanger is changed. The following are the results obtained in these experiments: (1) Inlet air of 30 C is lowered to about 0 C by passing the air through the heat exchanger, and absolute humidity of the outlet air is reduced to about a quarter of that of the inlet air. (2) There is an optimum height of the ice-cube-packed bed for maximizing the amount of cold energy released. (3) This heat exchange method can supply about twice the amount of cold energy released by an ordinary fin-tube-type heat exchanger even if the air velocity in the heat exchanger is reduced to about 0.38 times that of the fin-tube-type heat exchanger.

  7. Solar Air Heating Metal Roofing for Reroofing, New Construction, and Retrofit

    DTIC Science & Technology

    2013-05-20

    annual energy and life cycle savings from developing a solar assisted geothermal heating and cooling system . The project is funded by the Department...to the geothermal loop. The measurements proved the solar heated air resource and attic exhaust fan system are adequate for solar heat recovery to...support a geothermal heating system . Subsequent to the radiant barrier installation the overall geothermal project was reconfigured due to budget

  8. Low GWP Refrigerants Modelling Study for a Room Air Conditioner Having Microchannel Heat Exchangers

    SciTech Connect

    Shen, Bo; Bhandari, Mahabir S

    2016-01-01

    Microchannel heat exchangers (MHX) have found great successes in residential and commercial air conditioning applications, being compact heat exchangers, to reduce refrigerant charge and material cost. This investigation aims to extend the application of MHXs in split, room air conditioners (RAC), per fundamental heat exchanger and system modelling. For this paper, microchannel condenser and evaporator models were developed, using a segment-to-segment modelling approach. The microchannel heat exchanger models were integrated to a system design model. The system model is able to predict the performance indices, such as cooling capacity, efficiency, sensible heat ratio, etc. Using the calibrated system and heat exchanger models, we evaluated numerous low GWP (global warming potential) refrigerants. The predicted system performance indices, e.g. cooling efficiency, compressor discharge temperature, and required compressor displacement volume etc., are compared. Suitable replacements for R22 and R-410A for the room air conditioner application are recommended.

  9. Residential ventilation with heat recovery: Improving indoor air quality and saving energy

    NASA Astrophysics Data System (ADS)

    Roseme, G. D.; Berk, J. V.; Boegel, M. L.; Halsey, H. I.; Hollowell, C. D.; Rosenfeld, A. H.; Turiel, I.

    1980-05-01

    Residential air quality measurements were made and the use of mechanical ventilation systems with air-to-air heat exchangers is discussed as a promising means of pollutant control. A particular advantage of this control strategy is that the heat exchanger permits recovery of a large portion of the heat that would normally be lost in a simple exhaust ventilation system, and therefore maintains the energy efficiency of the house. An economic analysis is presented showing that installation of these systems in newly constructed homes is cost effective in most regions of the country.

  10. Preliminary design package for residential heating/cooling system: Rankine air conditioner redesign

    NASA Technical Reports Server (NTRS)

    1978-01-01

    A summary of the preliminary redesign and development of a marketable single family heating and cooling system is presented. The interim design and schedule status of the residential (3-ton) redesign, problem areas and solutions, and the definition of plans for future design and development activities were discussed. The proposed system for a single-family residential heating and cooling system is a single-loop, solar-assisted, hydronic-to-warm-air heating subsystem with solar-assisted domestic water heating and a Rankine-driven expansion air-conditioning subsystem.

  11. Energy Performance Comparison of Heating and Air Conditioning Systems for Multi-Family Residential Buildings

    SciTech Connect

    Wang, Weimin; Zhang, Jian; Jiang, Wei; Liu, Bing

    2011-07-31

    The type of heating, ventilation and air conditioning (HVAC) system has a large impact on the heating and cooling energy consumption in multifamily residential buildings. This paper compares the energy performance of three HVAC systems: a direct expansion (DX) split system, a split air source heat pump (ASHP) system, and a closed-loop water source heat pump (WSHP) system with a boiler and an evaporative fluid cooler as the central heating and cooling source. All three systems use gas furnace for heating or heating backup. The comparison is made in a number of scenarios including different climate conditions, system operation schemes and applicable building codes. It is found that with the minimum code-compliant equipment efficiency, ASHP performs the best among all scenarios except in extremely code climates. WSHP tends to perform better than the split DX system in cold climates but worse in hot climates.

  12. Experimental and theoretical study of shuttle lee-side heat transfer rates

    NASA Technical Reports Server (NTRS)

    Mruk, G. K.; Bertin, J.; Lamb, J. P.

    1975-01-01

    The experimental program which was conducted in the Calspan 96-inch hypersonic shock tunnel to investigate what effect the windward surface temperature had on the heat transfer to the leeward surface of the space shuttle orbiter is discussed. Heat-transfer distributions, surface-pressure distributions, and schlieren photographs were obtained for an 0.01-scale model of the 139 configuration space shuttle orbiter at angles-of-attack of 30 and 40 deg. Similar data were obtained for an 0.01 scale wingless model of the 139 configuration at angles-of-attack of 30 and 90 deg. Data were obtained for Mach numbers from Reynolds numbers, and surface temperatures and compared with theoretical results.

  13. Effects of air velocity and clothing combination on heating efficiency of an electrically heated vest (EHV): a pilot study.

    PubMed

    Wang, Faming; Gao, Chuansi; Holmér, Ingvar

    2010-09-01

    Cold endangers the heat balance of the human body. Protective clothing is the natural and most common equipment against cold stress. However, clothing for cold protection may be bulky and heavy, affecting human performance and increasing the work load. In such cases, a heated garment with built-in heating elements may be helpful. This pilot study presents a method based on a thermal manikin to investigate the effects of air velocity and clothing combination on the heating efficiency of an electrically heated vest (EHV). An infrared thermal camera was used to detect surface temperature distributions of the EHV on the front and back. Results show that the heating efficiency of the EHV decreases with increasing air velocity. Changes in EHV sequence in the three-layer clothing combination also significantly affect the heating efficiency: it increases with the increasing number of layers on top of the EHV. The highest mean temperature on the inner surface of the EHV was 40.2 degrees C, which indicates that it is safe for the wearers. For the EHV to heat the human body effectively, we suggest that it be worn as a middle layer. Finally, the EHV is especially suitable for occupational groups whose metabolic rate is below 1.9 Mets.

  14. Air-density-dependent model for analysis of air heating associated with streamers, leaders, and transient luminous events

    NASA Astrophysics Data System (ADS)

    Riousset, Jeremy A.; Pasko, Victor P.; Bourdon, Anne

    2010-12-01

    Blue and gigantic jets are transient luminous events in the middle atmosphere that form when conventional lightning leaders escape upward from the thundercloud. The conditions in the Earth's atmosphere (i.e., air density, reduced electric field, etc.) leading to conversion of hot leader channels driven by thermal ionization near cloud tops to nonthermal streamer forms observed at higher altitudes are not understood at present. This paper presents a formulation of a streamer-to-spark transition model that allows studies of gas dynamics and chemical kinetics involved in heating of air in streamer channels for a given air density N under assumption of constant applied electric field E. The model accounts for the dynamic expansion of the heated air in the streamer channel and resultant effects of E/N variations on plasma kinetics, the vibrational excitation of nitrogen molecules N2(v), effects of gains in electron energy in collisions with N2(v), and associative ionization processes involving N2(A3Σu+) and N2(a'1Σu-) species. The results are in excellent agreement with available experimental data at ground and near-ground air pressures and demonstrate that for the air densities corresponding to 0-70 km altitudes the kinetic effects lead to a significant acceleration of the heating, with effective heating times scaling closer to 1/N than to 1/N2 predicted on the basis of similarity laws for Joule heating. This acceleration is attributed to a strong reduction in electron losses due to three-body attachment and electron-ion recombination processes with reduction of air pressure.

  15. Sawtooth control in JET with ITER relevant low field side resonance ion cyclotron resonance heating and ITER-like wall

    NASA Astrophysics Data System (ADS)

    Graves, J. P.; Lennholm, M.; Chapman, I. T.; Lerche, E.; Reich, M.; Alper, B.; Bobkov, V.; Dumont, R.; Faustin, J. M.; Jacquet, P.; Jaulmes, F.; Johnson, T.; Keeling, D. L.; Liu, Yueqiang; Nicolas, T.; Tholerus, S.; Blackman, T.; Carvalho, I. S.; Coelho, R.; Van Eester, D.; Felton, R.; Goniche, M.; Kiptily, V.; Monakhov, I.; Nave, M. F. F.; Perez von Thun, C.; Sabot, R.; Sozzi, C.; Tsalas, M.

    2015-01-01

    New experiments at JET with the ITER-like wall show for the first time that ITER-relevant low field side resonance first harmonic ion cyclotron resonance heating (ICRH) can be used to control sawteeth that have been initially lengthened by fast particles. In contrast to previous (Graves et al 2012 Nat. Commun. 3 624) high field side resonance sawtooth control experiments undertaken at JET, it is found that the sawteeth of L-mode plasmas can be controlled with less accurate alignment between the resonance layer and the sawtooth inversion radius. This advantage, as well as the discovery that sawteeth can be shortened with various antenna phasings, including dipole, indicates that ICRH is a particularly effective and versatile tool that can be used in future fusion machines for controlling sawteeth. Without sawtooth control, neoclassical tearing modes (NTMs) and locked modes were triggered at very low normalised beta. High power H-mode experiments show the extent to which ICRH can be tuned to control sawteeth and NTMs while simultaneously providing effective electron heating with improved flushing of high Z core impurities. Dedicated ICRH simulations using SELFO, SCENIC and EVE, including wide drift orbit effects, explain why sawtooth control is effective with various antenna phasings and show that the sawtooth control mechanism cannot be explained by enhancement of the magnetic shear. Hybrid kinetic-magnetohydrodynamic stability calculations using MISHKA and HAGIS unravel the optimal sawtooth control regimes in these ITER relevant plasma conditions.

  16. Correlation analysis of transient heat transfer characteristics for air precooling aggregate

    NASA Astrophysics Data System (ADS)

    Guo, Chaohong; Zeng, Miao; Lu, Fei; Tang, Dawei; Guan, Wei; Li, Li; Fu, Tingwu

    2017-04-01

    In dam works, air precooling of aggregate is a common and effective method to avoid temperature cracks in concrete structure. In order to offer a reliable design theory for the air precooling process to avoid unreasonable energy consumption, the transient heat transfer characteristics of the aggregate are intensively analyzed. The combined structure of the aggregate and the interstitial space in the hopper is treated as a porous structure, and the space-average method is used to simulate the transient heat transfer process. Simulation results show that size of the hopper and the average air velocity in the cross section have great influence on the transient heat transfer process of the aggregate, while the porosity in the range of 0.4‒0.5 has little influence. Nomograms are abstracted from simulation results, and then correlations of the compared excess temperature are precisely fitted to predict the air precooling transient heat transfer process of the aggregate.

  17. Improved Modeling of Residential Air Conditioners and Heat Pumps for Energy Calculations

    SciTech Connect

    Cutler, D.; Winkler, J.; Kruis, N.; Christensen, C.; Brendemuehl, M.

    2013-01-01

    This report presents improved air conditioner and heat pump modeling methods in the context of whole-building simulation tools, with the goal of enabling more accurate evaluation of cost effective equipment upgrade opportunities and efficiency improvements in residential buildings.

  18. Coolant side heat transfer with rotation: User manual for 3D-TEACH with rotation

    NASA Technical Reports Server (NTRS)

    Syed, S. A.; James, R. H.

    1989-01-01

    This program solves the governing transport equations in Reynolds average form for the flow of a 3-D, steady state, viscous, heat conducting, multiple species, single phase, Newtonian fluid with combustion. The governing partial differential equations are solved in physical variables in either a Cartesian or cylindrical coordinate system. The effects of rotation on the momentum and enthalpy calculations modeled in Cartesian coordinates are examined. The flow of the fluid should be confined and subsonic with a maximum Mach number no larger than 0.5. This manual describes the operating procedures and input details for executing a 3D-TEACH computation.

  19. Heat shock protein 10 (Hsp10) in immune-related diseases: one coin, two sides

    PubMed Central

    Jia, Haibo; Halilou, Amadou I.; Hu, Liang; Cai, Wenqian; Liu, Jing; Huang, Bo

    2011-01-01

    Heat shock protein 10 (Hsp10) in eukaryotes, originally identified as a mitochondrial chaperone, now is also known to be present in cytosol, cell surface, extracellular space and peripheral blood. Functionally besides participating in mitochondrial protein folding in association with Hsp60, Hsp10 appears to be related to pregnancy, cancer and autoimmune inhibition. Hsp10 can be released to peripheral blood at very early time point of pregnancy and given another name called early pregnancy factor (EPF), which seems to play a critical role in developing a pregnant niche. In malignant disorders, Hsp10 is usually abnormally expressed in the cytosol of malignant cells and further released to extracellular space, resulting in tumor-promoting effect from various aspects. Furthermore, distinct from other heat shock protein members, whose soluble form is recognized as danger signal by immune cells and triggers immune responses, Hsp10 after release, however, is designed to be an inhibitory signal by limiting immune response. This review discusses how Hsp10 participates in various physiological and pathological processes from basic protein molecule folding to pregnancy, cancer and autoimmune diseases, and emphasizes how important the location is for the function exertion of a molecule. PMID:21969171

  20. Measured Performance of a Low Temperature Air Source Heat Pump

    SciTech Connect

    Johnson, R. K.

    2013-09-01

    A 4-ton Low Temperature Heat Pump (LTHP) manufactured by Hallowell International was installed in a residence near New Haven, Connecticut and monitored over two winters of operation. After attending to some significant service issues, the heat pump operated as designed. This report should be considered a review of the dual compressor 'boosted heat pump' technology. The Low Temperature Heat Pumpsystem operates with four increasing levels of capacity (heat output) as the outdoor temperature drops. The system was shown to select capacity correctly, supplying the appropriate amount of heat to the house across the full range of outdoor temperatures. The system's Coefficient of Performance (Seasonal COP, or SCOP) over two entire winters was calculated, based on measured data, to be 3.29over the first winter and 2.68 over the second winter. A second seasonal efficiency calculation by a different method yielded a SCOP of 2.78 for the first winter and 2.83 for the second winter. This second seasonal efficiency calculation was determined by comparing measured heat pump energy use to the in situ energy use with resistance heat alone. This method is the ratio of the slopes of thedaily energy use load lines.

  1. The Human Side of Cyber Conflict: Organizing, Training, and Equipping the Air Force Cyber Workforce

    DTIC Science & Technology

    2016-06-01

    toward cyber operations but also a grasp of legal , policy, and ethical issues related to cyber operations and national se- curity. However, this cadre is...competitions provide legal outlets for students with creative computer skills. From these competitions and through its sponsorship of and advertising at these...flexibility to reliably move Airmen as needed, we recommend that the Air Force explore the legalities of including noncompete clauses to restrict

  2. An inexact double-sided chance-constrained model for air quality management in Nanshan District, Shengzhen, China

    NASA Astrophysics Data System (ADS)

    Shao, Liguo; Xu, Ye; Huang, Guohe

    2014-12-01

    In this study, an inexact double-sided fuzzy-random-chance-constrained programming (IDSFRCCP) model was developed for supporting air quality management of the Nanshan District of Shenzhen, China, under uncertainty. IDSFRCCP is an integrated model incorporating interval linear programming and double-sided fuzzy-random-chance-constrained programming models. It can express uncertain information as both fuzzy random variables and discrete intervals. The proposed model was solved based on the stochastic and fuzzy chance-constrained programming techniques and an interactive two-step algorithm. The air quality management system of Nanshan District, including one pollutant, six emission sources, six treatment technologies and four receptor sites, was used to demonstrate the applicability of the proposed method. The results indicated that the IDSFRCCP was capable of helping decision makers to analyse trade-offs between system cost and risk of constraint violation. The mid-range solutions tending to lower bounds with moderate αh and qi values were recommended as decision alternatives owing to their robust characteristics.

  3. Colonization by Cladosporium spp. of painted metal surfaces associated with heating and air conditioning systems

    NASA Technical Reports Server (NTRS)

    Ahearn, D. G.; Simmons, R. B.; Switzer, K. F.; Ajello, L.; Pierson, D. L.

    1991-01-01

    Cladosporium cladosporioides and C. hebarum colonized painted metal surfaces of covering panels and register vents of heating, air conditioning and ventilation systems. Hyphae penetrated the paint film and developed characteristic conidiophores and conidia. The colonies were tightly appressed to the metal surface and conidia were not readily detectable via standard air sampling procedures.

  4. 10 CFR 429.16 - Central air conditioners and heat pumps.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... CONSUMER PRODUCTS AND COMMERCIAL AND INDUSTRIAL EQUIPMENT Certification § 429.16 Central air conditioners... mean divided by 1.05, where: ER02MY11.030 and (B) Any represented value of the energy efficiency or other measure of energy consumption of the central air conditioner or heat pump for which...

  5. 10 CFR 429.16 - Central air conditioners and heat pumps.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... CONSUMER PRODUCTS AND COMMERCIAL AND INDUSTRIAL EQUIPMENT Certification § 429.16 Central air conditioners... mean divided by 1.05, where: ER02MY11.030 and (B) Any represented value of the energy efficiency or other measure of energy consumption of the central air conditioner or heat pump for which...

  6. 10 CFR 429.16 - Central air conditioners and heat pumps.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... CONSUMER PRODUCTS AND COMMERCIAL AND INDUSTRIAL EQUIPMENT Certification § 429.16 Central air conditioners... mean divided by 1.05, where: ER02MY11.030 and (B) Any represented value of the energy efficiency or other measure of energy consumption of the central air conditioner or heat pump for which...

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

    SciTech Connect

    Bohn, M.S.

    1988-11-01

    This paper presents a comparison of experimental data with a recently published model of heat exchange in irrigated packed beds. Heat transfer and pressure drop were measured in a 150 mm (ID) column with a 610-mm bed of metal Pall rings. Molten nitrate salt and preheated air were the working fluids with a salt inlet temperature of approximately 440{degree}C and air inlet temperatures of approximately 230{degree}C. A comparison between the experimental data and the heat transfer model is made on the basis of heat transfer from the salt. For the range of air and salt flow rates tested, 0.3 to 1.2 kg/m{sup 2} s air flow and 6 to 18 kg/m{sup 2} s salt flow, the data agree with the model within 22% standard deviation. In addition, a model for the column pressure drop was validated, agreeing with the experimental data within 18% standard deviation over the range of column pressure drop from 40 to 1250 Pa/m. 25 refs., 7 figs., 2 tabs.

  8. Capability of air filters to retain airborne bacteria and molds in heating, ventilating and air-conditioning (HVAC) systems.

    PubMed

    Möritz, M; Peters, H; Nipko, B; Rüden, H

    2001-07-01

    The capability of air filters (filterclass: F6, F7) to retain airborne outdoor microorganisms was examined in field experiments in two heating, ventilating and air conditioning (HVAC) systems. At the beginning of the 15-month investigation period, the first filter stages of both HVAC systems were equipped with new unused air filters. The number of airborne bacteria and molds before and behind the filters were determined simultaneously in 14 days-intervals using 6-stage Andersen cascade impactors. Under relatively dry (< 80% R. H.) and warm (> 12 degrees C) outdoor air conditions air filters led to a marked reduction of airborne microorganism concentrations (bacteria by approximately 70% and molds by > 80%). However, during long periods of high relative humidity (> 80% R. H.) a proliferation of bacteria on air filters with subsequent release into the filtered air occurred. These microorganisms were mainly smaller than 1.1 microns therefore being part of the respirable fraction. The results showed furthermore that one possibility to avoid microbial proliferation is to limit the relative humidity in the area of the air filters to 80% R. H. (mean of 3 days), e.g. by using preheaters in front of air filters in HVAC-systems.

  9. Opportunities for Saving Energy and Improving Air Quality in Urban Heat Islands

    SciTech Connect

    Akbari, Hashem

    2007-07-01

    World energy use is the main contributor to atmospheric CO2. In 2002, about 7.0 giga metric tons of carbon (GtC) were emitted internationally by combustion of gas, liquid, and solid fuels (CDIAC, 2006), 2 to 5 times the amount contributed by deforestation (Brown et al., 1988). The share of atmospheric carbon emissions for the United States from fossil fuel combustion was 1.6 GtC. Increasing use of fossil fuel and deforestation together have raised atmospheric CO{sub 2} concentration some 25% over the last 150 years. According to global climate models and preliminary measurements, these changes in the composition of the atmosphere have already begun raising the Earth's average temperature. If current energy trends continue, these changes could drastically alter the Earth's temperature, with unknown but potentially catastrophic physical and political consequences. During the last three decades, increased energy awareness has led to conservation efforts and leveling of energy consumption in the industrialized countries. An important byproduct of this reduced energy use is the lowering of CO{sub 2} emissions. Of all electricity generated in the United States, about one-sixth is used to air-condition buildings. The air-conditioning use is about 400 tera-watt-hours (TWh), equivalent to about 80 million metric tons of carbon (MtC) emissions, and translating to about $40 billion (B) per year. Of this $40 B/year, about half is used in cities that have pronounced 'heat islands'. The contribution of the urban heat island to the air-conditioning demand has increased over the last 40 years and it is currently at about 10%. Metropolitan areas in the United States (e.g., Los Angeles, Phoenix, Houston, Atlanta, and New York City) have typically pronounced heat islands that warrant special attention by anyone concerned with broad-scale energy efficiency (HIG, 2006). The ambient air is primarily heated through three processes: direct absorption of solar radiation, convection of heat

  10. Criteria for Side-Force Control in Air-to-Ground Target Acquisition and Tracking

    NASA Technical Reports Server (NTRS)

    Sammonds, Robert I.; McNeill, Walter E.; Bunnell, John W.

    1982-01-01

    A moving-base simulator experiment conducted at Ames Research Center demonstrated that a wings-level-turn control mode improved flying qualities for air-to-ground weapons delivery compared with those of a conventional aircraft. Evaluations of criteria for dynamic response for this system have shown that pilot ratings correlate well with equivalent time constant of the initial response and with system bandwidth. Ranges of this time constant, as well as digital-system transport delays and lateral-acceleration control authorities that encompassed level 1 through level 3 handling qualities, were determined.

  11. A Procedure for the Design of Air-Heated Ice-Prevention Systems

    NASA Technical Reports Server (NTRS)

    Neel, C. B.

    1954-01-01

    A procedure proposed for use in the design of air-heated systems for the continuous prevention of ice formation on airplane components is set forth. Required heat-transfer and air-pressure-loss equations are presented, and methods of selecting appropriate meteorological conditions for flight over specified geographical areas and for the calculation of water-drop-impingement characteristics are suggested. In order to facilitate the design, a simple electrical analogue was devised which solves the complex heat-transfer relationships existing in the thermal-system analysis. The analogue is described and an illustration of its application to design is given.

  12. Subterranean heat exchanger for refrigeration air conditioning equipment

    SciTech Connect

    Rothwell, H.

    1980-09-30

    Heat exchanger apparatus for use with refrigeration cycle heating and cooling equipment is disclosed. In the preferred embodiment, it cooperates with and modifies refrigeration equipment including a compressor, an expansion valve, an evaporator coil and a closed loop for cycling refrigerant. This apparatus is a sealed container adapted to be placed in a well extending into artesian (Relatively heated or chilled) formations whereby the water of the formation stabilizes the temperature around the unit and enables heating and cooling. The sealed unit receives refrigerant from the top which flows along the sidewall at a reduced temperature, thereby condensing on the sidewall and trickling down the sidewall to collect in a sump at the bottom where the compressor pump picks up condensed refrigerant as a liquid and pumps it out of the artesian well to the connected refrigeration equipment.

  13. Coolant side heat transfer with rotation. Task 3 report: Application of computational fluid dynamics

    NASA Technical Reports Server (NTRS)

    Kopper, F. C.; Sturgess, G. J.; Datta, P.

    1989-01-01

    An experimental and analytical program was conducted to investigate heat transfer and pressure losses in rotating multipass passages with configurations and dimensions typical of modern turbine blades. The objective of this program is the development and verification of improved analysis methods that will form the basis for a design system that will produce turbine components with improved durability. As part of this overall program, a technique is developed for computational fluid dynamics. The specific objectives were to: select a baseline CFD computer code, assess the limitations of the baseline code, modify the baseline code for rotational effects, verify the modified code against benchmark experiments in the literature, and to identify shortcomings in the code as revealed by the verification. The Pratt and Whitney 3D-TEACH CFD code was selected as the vehicle for this program. The code was modified to account for rotating internal flows, and these modifications were evaluated for flow characteristics of those expected in the application. Results can make a useful contribution to blade internal cooling.

  14. Combined Heat, Air, Moisture, and Pollutants Transport in Building Environmental Systems

    NASA Astrophysics Data System (ADS)

    Zhang, Jianshun Jensen S.

    Combined heat, air, moisture and pollutants transport (CHAMP) exists across multi-scales of a building environmental system (BES): around the building, through the building shell/envelope, inside a multizone building, and in the micro-environments around occupants. This paper reviews previous work and presents a system model for simulating these transport processes and their impacts on indoor environmental quality. Components of the system model include a multizone network flow model for whole building, a room model for air and pollutant movement in ventilated spaces, a coupled heat, air, moisture, and pollutant transport model for building shell, an HVAC model for describing the dynamics of the heating, ventilating and air-conditioning (HVAC) system, and shared databases of weather conditions, transport properties of building materials, and volatile organic compounds (VOCs) emissions from building materials and furnishings. The interactions among the different components, and challenges in developing the CHAMP system model for intelligent control of BES are also discussed.

  15. Experimental study on heat transfer performance of aluminium foam parallel-flow condenser in air conditioner

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Wan, Z. M.; Chang, H. W.; Wang, Y. D.

    2017-01-01

    Open cell aluminium foam was used in parallel-flow condenser in air conditioner, and two condensers with different pore density were fabricated. The experimental study was conducted on the heat transfer performance and temperature distribution. The experimental results show that both of the heat transfer load and air pressure drop increase with the increase of pore density, air velocity is 2.5m/s, the heat transfer capacities of the condenser with 10PPI and 8PPI are 4.786kw and 3.344kW respectively. Along the flow direction of refrigerant, the outlet temperatures of refrigerant drop with the rise of air velocity when the inlet temperature is constant. The outlet temperature of the refrigerant decreases with the increase of pore density.

  16. Heat transfer and energy analysis of a solar air collector with smooth plate

    NASA Astrophysics Data System (ADS)

    Chabane, Foued; Moummi, Noureddine

    2014-04-01

    The heat transfer and thermal performance of a single pass solar air heater a smooth plate was investigated experimentally. In the present paper, energy and heat transfer analysis of a solar air collector with smooth plate, this technique is used to determine the optimal thermal performance of flat plate solar air heater by considering the different system and operating parameters to obtain maximum thermal performance. Thermal performance is obtained for different mass flow rate varying in the array 0.0108-0.0202 kg/s with five values, solar intensity; tilt angle and ambient temperature. We discuss the thermal behavior of this type of collector with new design and with my proper construction. An experimental study was carried out on a prototype installed on the experimental tests platform within the University of Biskra in the Algeria. The effects of air mass flow rate, emissivity of channel plates and wind heat transfer coefficient on the accuracy of the criterion are also investigated.

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

    PubMed

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

    2011-01-01

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

  18. Heat exchanger design for hot air ericsson-brayton piston engine

    NASA Astrophysics Data System (ADS)

    Ďurčanský, P.; Lenhard, R.; Jandačka, J.

    2014-03-01

    One of the solutions without negative consequences for the increasing energy consumption in the world may be use of alternative energy sources in micro-cogeneration. Currently it is looking for different solutions and there are many possible ways. Cogeneration is known for long time and is widely used. But the installations are often large and the installed output is more suitable for cities or industry companies. When we will speak about decentralization, the small machines have to be used. The article deals with the principle of hot-air engines, their use in combined heat and electricity production from biomass and with heat exchangers as primary energy transforming element. In the article is hot air engine presented as a heat engine that allows the conversion of heat into mechanical energy while heat supply can be external. In the contribution are compared cycles of hot-air engine. Then are compared suitable heat exchangers for use with hot air Ericsson-Brayton engine. In the final part is proposal of heat exchanger for use in closed Ericsson-Brayton cycle.

  19. HEAT exchanger design for hot air Ericsson-Brayton piston engine

    NASA Astrophysics Data System (ADS)

    Ďurčanský, Peter; Lenhard, Richard; Jandačka, Jozef

    2013-10-01

    One of the solutions without negative consequences for the increasing energy consumption in the world may be use of alternative energy sources in micro-cogeneration. Currently it is looking for different solutions and there are many possible ways. Cogeneration is known for long time and is widely used. But the installations are often large and the installed output is more suitable for cities or industry companies. When we will speak about decentralization, the small machines have to be used. The article deals with the principle of hot-air engines, their use in combined heat and electricity production from biomass and with heat exchangers as primary energy transforming element. In the article is hot air engine presented as a heat engine that allows the conversion of heat into mechanical energy while heat supply can be external. In the contribution are compared cycles of hot-air engine. Then are compared suitable heat exchangers for use with hot air Ericsson-Brayton engine. In the final part is proposal of heat exchanger for use in closed Ericsson-Brayton cycle.

  20. Biomass combustion and indoor air pollution: the bright and dark sides of small is beautiful

    NASA Astrophysics Data System (ADS)

    Smith, Kirk R.

    1986-01-01

    About half the world's households cook and/or heat daily with biomass fuels. At small scale, biomass combustion releases significant amounts of particulates, carbon monoxide, and hydrocarbons, the latter with significant concentrations of polycyclic aromatic hydrocarbons. Preliminary measurements in kitchens of developing-country villages have established airborne concentrations of these healthdamaging pollutants that are orders of magnitude above urban levels or relevant standards. Particle size measurements and dose calculations lead to significant concerns about potential health hazards. The few epidemiological studies are consistent with such effects although more work is clearly needed. These findings may have significant implications for the planning of rural energy development in a number of countries. In particular, they may relate directly to the question of the optimum balance between centralized and decentralized systems.

  1. Overall heat transfer coefficient and pressure drop in a typical tubular exchanger employing alumina nano-fluid as the tube side hot fluid

    NASA Astrophysics Data System (ADS)

    Kabeel, A. E.; Abdelgaied, Mohamed

    2016-08-01

    Nano-fluids are used to improve the heat transfer rates in heat exchangers, especially; the shell-and-tube heat exchanger that is considered one of the most important types of heat exchangers. In the present study, an experimental loop is constructed to study the thermal characteristics of the shell-and-tube heat exchanger; at different concentrations of Al2O3 nonmetallic particles (0.0, 2, 4, and 6 %). This material concentrations is by volume concentrations in pure water as a base fluid. The effects of nano-fluid concentrations on the performance of shell and tube heat exchanger have been conducted based on the overall heat transfer coefficient, the friction factor, the pressure drop in tube side, and the entropy generation rate. The experimental results show that; the highest heat transfer coefficient is obtained at a nano-fluid concentration of 4 % of the shell side. In shell side the maximum percentage increase in the overall heat transfer coefficient has reached 29.8 % for a nano-fluid concentration of 4 %, relative to the case of the base fluid (water) at the same tube side Reynolds number. However; in the tube side the maximum relative increase in pressure drop has recorded the values of 12, 28 and 48 % for a nano-material concentration of 2, 4 and 6 %, respectively, relative to the case without nano-fluid, at an approximate value of 56,000 for Reynolds number. The entropy generation reduces with increasing the nonmetallic particle volume fraction of the same flow rates. For increase the nonmetallic particle volume fraction from 0.0 to 6 % the rate of entropy generation decrease by 10 %.

  2. The New S-RAM Air Variable Compressor/Expander for Heat Pump and Waste Heat to Power Application

    SciTech Connect

    Dehoff, Ryan R; Jestings, Lee; Conde, Ricardo

    2016-05-23

    S-RAM Dynamics (S-RAM) has designed an innovative heat pump system targeted for commercial and industrial applications. This new heat pump system is more efficient than anything currently on the market and utilizes air as the refrigerant instead of hydrofluorocarbon (HFC) refrigerants, leading to lower operating costs, minimal environmental costs or concerns, and lower maintenance costs. The heat pumps will be manufactured in the United States. This project was aimed at determining the feasibility of utilizing additive manufacturing to make the heat exchanger device for the new heat pump system. ORNL and S-RAM Dynamics collaborated on determining the prototype performance and subsequently printing of the prototype using additive manufacturing. Complex heat exchanger designs were fabricated using the Arcam electron beam melting (EBM) powder bed technology using Ti-6Al-4V material. An ultrasonic welding system was utilized in order to remove the powder from the small openings of the heat exchanger. The majority of powder in the small chambers was removed, however, the amount of powder remaining in the heat exchanger was a function of geometry. Therefore, only certain geometries of heat exchangers could be fabricated. SRAM Dynamics evaluated a preliminary heat exchanger design. Although the results of the additive manufacturing of the heat exchanger were not optimum, a less complex geometry was demonstrated. A sleeve valve was used as a demonstration piece, as engine designs from S-RAM Dynamics require the engine to have a very high density. Preliminary designs of this geometry were successfully fabricated using the EBM technology.

  3. Heat transfer analysis for high temperature preheated air combustion in furnace

    SciTech Connect

    Taniguchi, H.; Arai, N.; Kudo, K.; Aoki, K.

    1998-07-01

    The high temperature preheated air combustion system has been recently developed and techniques of heat transfer analysis pose important problems in its application to the industrial field. The three-dimensional simulation has to be introduced, therefore, for the above heat transfer analysis with combustion, fluid flow and heat transfer. Another effort may be introduced to reduce the computing time of heat transfer analysis by means of some simplification in software of chemical simulation, etc. If one has introduced the application of the high temperature preheated air combustion technique in natural gas firing, the non-gray radiation should be applied to each radiant gas of CO{sub 2}, H{sub 2}O, CO or CH{sub 4}, in this analysis. Finally, the authors would like to refer the inverse computation of radiation heat transfer in furnace which has been proposed by one of the authors and another researcher in the United States. If one tries to estimate the performance of an industrial furnace, the heat flux on heating material is the most important factor which has been fixed as input data of computation. Therefore, the heat transfer analysis may be sometimes reversed by fixed data of heat flux and proceeded by trial and error method, in order to obtain the initial condition of heat source and furnace facilities.

  4. Desiccant outdoor air preconditioners maximize heat recovery ventilation potentials

    SciTech Connect

    Meckler, M.

    1995-12-31

    Microorganisms are well protected indoors by the moisture surrounding them if the relative humidity is above 70%. They can cause many acute diseases, infections, and allergies. Humidity also has an effect on air cleanliness and causes the building structure and its contents to deteriorate. Therefore, controlling humidity is a very important factor to human health and comfort and the structural longevity of a building. To date, a great deal of research has been done, and is continuing, in the use of both solid and liquid desiccants. This paper introduces a desiccant-assisted system that combines dehumidification and mechanical refrigeration by means of a desiccant preconditioning module that can serve two or more conventional air-conditioning units. It will be demonstrated that the proposed system, also having indirect evaporative cooling within the preconditioning module, can reduce energy consumption and provide significant cost savings, independent humidity and temperature control, and, therefore, improved indoor air quality and enhanced occupant comfort.

  5. Natural convection heat transfer from horizontal concentric and eccentric cylinder systems cooling in the ambient air and determination of inner cylinder location

    NASA Astrophysics Data System (ADS)

    Atayılmaz, Ş. Özgür; Demir, Hakan; Sevindir, Mustafa Kemal; Ağra, Özden; Teke, İsmail; Dalkılıç, Ahmet Selim

    2017-03-01

    Heat transfer characteristics of horizontal copper concentric cylinders in the case of natural convection was investigated numerically and experimentally. While the inner cylinder had an electric heater to keep it at a constant temperature, annulus was filled with water. There were two different test sections as bare and concentric cylinder systems located in different ambient temperatures in a conditioned room for the comparison of the results. Comparison of average Nusselt numbers for the air side of the concentric cylinder system and the effective thermal conductivity of the annulus were calculated with both experimental data, numerical results and a well-known correlation. Annulus and the air side isotherms and streamlines are shown for RaL = 9 × 105-5 × 106 and Ra = 2 × 105-7 × 105 respectively. Additionally, a numerical study was conducted by forming eccentric cylinder systems to determine the optimum location of inner cylinder to maximize the heat transfer rate. Comparison of heat transfer rates from bare and concentric horizontal cylinders were done under steady state conditions. Heat transfer enhancement, the effect of the decrease in condensing temperature of the inner cylinder surface on COP of an ideal Carnot refrigeration cycle and rise in COP were determined in the study. Also the optimum location of inner cylinder to maximize the heat transfer rate was determined as at the bottom quadrant of outer cylinder.

  6. Rapid PCR amplification using a microfluidic device with integrated microwave heating and air impingement cooling.

    PubMed

    Shaw, Kirsty J; Docker, Peter T; Yelland, John V; Dyer, Charlotte E; Greenman, John; Greenway, Gillian M; Haswell, Stephen J

    2010-07-07

    A microwave heating system is described for performing polymerase chain reaction (PCR) in a microfluidic device. The heating system, in combination with air impingement cooling, provided rapid thermal cycling with heating and cooling rates of up to 65 degrees C s(-1) and minimal over- or under-shoot (+/-0.1 degrees C) when reaching target temperatures. In addition, once the required temperature was reached it could be maintained with an accuracy of +/-0.1 degrees C. To demonstrate the functionality of the system, PCR was successfully performed for the amplification of the Amelogenin locus using heating rates and quantities an order of magnitude faster and smaller than current commercial instruments.

  7. Experimental study of laminar flow forced-convection heat transfer in air flowing through offset plates heated by radiation heat flux

    SciTech Connect

    Ali, A.H.H.; Kishinami, Koki; Hanaoka, Yutaka; Suzuki, Jun

    1998-04-01

    An experimental study of the steady state laminar flow forced-convection heat transfer of air flowing through offset plates located between two parallel plates and heated by radiation heat flux was carried out. The ranges of parameters tested were incident radiation heat fluxes of 500, 700, and 1,000 W/m{sup 2}. With Re ranging from 650 to 2,560, the inlet air bulk temperatures changed from 18.2 to 70 C and the tilting angle of the unit with the horizontal ranged from 0 to 90{degree} respectively. The results show that the rate of the increase in the local Nusselt number was observed to be proportional with Re up to 1,900, while it became less sensitive over Re range of 1,900--2,500. Also, in this range of Re, with the inlet air temperature of 20 C, the angle of inclination of the unit has no effect on the local Nusselt number. Increasing the incident radiation heat flux in the case of higher values of Re leads to a slight decrease in the value of the local Nusselt number. The effect of the inlet air bulk temperature on the forced-convection heat transfer coefficient shows, in the case of the horizontal position, an increase in the inlet air bulk temperature leads to slight decreases in the value of the average Nusselt number, while it leads to significant decreases in the value of the average Nusselt number as the tilting angle increases up to the vertical position. This effect is clearer in the case of Re = 650 rather than Re = 2,550. This work has application to solar collectors.

  8. [Verification of exhaled air temperature and heat flux in respiratory diseases as useful biomarker].

    PubMed

    Ito, Wataru; Chihara, Junichi

    2008-12-01

    Asthma, chronic obstructive pulmonary disease, and diffuse panbronchiolitis are syndromes associated with chronic airway inflammation. In the conventional definition of inflammation, local pyrexia at the site of inflammation should be observed. However, there are very few reports that have evaluated the "heat" in inflammatory respiratory diseases. We considered that the evaluation of allergic airway inflammation such as asthma might be possible by measuring the exhaled air temperature, and devised an original device that stabilizes the flow rate, which is a very important factor for the direct measurement of heat. Moreover, an expiratory heat flux meter, which can detect a change in air temperature more precisely and immediately, was also incorporated into our original device. As a result, we succeeded in the measurement and evaluation of the heat flux and air temperature in healthy subjects and asthmatic patients, and, further, the air temperature was straightforwardly evaluated by a portable spirometer including a temperature sensor. These findings suggest that the heat flux and temperature of exhaled air can be used to objectively monitor airway inflammation noninvasively, and assist in the diagnosis/monitoring of inflammatory respiratory diseases, including asthma.

  9. Air pollution and heat exposure study in the workplace in a glass manufacturing unit in India.

    PubMed

    Bhanarkar, A D; Srivastava, A; Joseph, A E; Kumar, Rakesh

    2005-10-01

    Air pollution in the workplace environment due to industrial operation have been found to cause serious occupational health hazard. Similarly, heat stress is still most neglected occupational hazard in the tropical and subtropical countries like India. The hot climate augments the heat exposure close to sources like furnaces. In this study an attempt is made to assess air pollution and heat exposure levels to workers in the workplace environment in glass manufacturing unit located in the State of Gujarat, India. Samples for workplace air quality were collected for SPM, SO(2), NO(2) and CO(2) at eight locations. Results of workplace air quality showed 8-hourly average concentrations of SPM: 165-9118 microg/m(3), SO(2): 6-9 microg/m(3) and NO(2): 5-42 microg/m(3), which were below the threshold limit values of workplace environment. The level of CO(2) in workplace air of the plant was found to be in the range 827-2886 microg/m(3), which was below TLV but much higher than the normal concentration for CO(2) in the air (585 mg/m(3)). Indoor heat exposure was studied near the furnace and at various locations in an industrial complex for glass manufacturing. The heat exposure parameters including the air temperature, the wet bulb temperature, and the globe parameters were measured. The Wet Bulb Globe Temperature (WBGT), an indicator of heat, exceeded ACGIH TLVs limits most of the time at all the locations in workplace areas. The recommended duration of work and rest have also been estimated.

  10. Experimental investigation on performance of ice storage air-conditioning system with separate heat pipe

    SciTech Connect

    Fang, Guiyin; Liu, Xu; Wu, Shuangmao

    2009-11-15

    An experimental study on operation performance of ice storage air-conditioning system with separate helical heat pipe is conducted in this paper. The experimental system of ice storage air-conditioning system with separate heat pipe is set up. The performance parameters such as the evaporation pressure and the condensation pressure of refrigeration system, the refrigeration capacity and the COP (coefficient of performance) of the system, the IPF (ice packing factor) and the cool storage capacity in the cool storage tank during charging period, and the cool discharge rate and the cool discharge capacity in the cool storage tank, the outlet water temperature in the cool storage tank and the outlet air temperature in room unit during discharging period are investigated. The experimental results show that the ice storage air-conditioning system with separate helical heat pipe can stably work during charging and discharging period. This indicates that the ice storage air-conditioning system with separate helical heat pipe is well adapted to cool storage air-conditioning systems in building. (author)

  11. Effect of heterogenous and homogenous air gaps on dry heat loss through the garment.

    PubMed

    Mert, Emel; Psikuta, Agnes; Bueno, Marie-Ange; Rossi, René M

    2015-11-01

    In real life conditions, the trapped air between the human body and the garment has uneven shape and vary over the body parts as a consequence of the complex geometry of the human body. However, the existing clothing models assume uniform air layer between the human body and the garment or its full contact, which may cause large error in the output of simulations. Therefore, the aim of this study was to investigate the effect of a heterogeneous vertical air gap with different configuration of folds (size and frequency) on dry heat loss using a heated cylinder (Torso). It was found that the presence of folds in the garment led to an increased heat loss from the body in comparison to a homogeneous air gap of comparable size. Interestingly, the size of folds did not have an influence on the dry heat loss. Additionally, the effect of the contact area on dry heat loss became important when exceeding a threshold of about 42%. The results from this study are useful for modelling of a realistic dry heat loss through the clothing and contribute to the improvement of design of protective and active sport garments.

  12. Effect of heterogenous and homogenous air gaps on dry heat loss through the garment

    NASA Astrophysics Data System (ADS)

    Mert, Emel; Psikuta, Agnes; Bueno, Marie-Ange; Rossi, René M.

    2015-11-01

    In real life conditions, the trapped air between the human body and the garment has uneven shape and vary over the body parts as a consequence of the complex geometry of the human body. However, the existing clothing models assume uniform air layer between the human body and the garment or its full contact, which may cause large error in the output of simulations. Therefore, the aim of this study was to investigate the effect of a heterogeneous vertical air gap with different configuration of folds (size and frequency) on dry heat loss using a heated cylinder (Torso). It was found that the presence of folds in the garment led to an increased heat loss from the body in comparison to a homogeneous air gap of comparable size. Interestingly, the size of folds did not have an influence on the dry heat loss. Additionally, the effect of the contact area on dry heat loss became important when exceeding a threshold of about 42 %. The results from this study are useful for modelling of a realistic dry heat loss through the clothing and contribute to the improvement of design of protective and active sport garments.

  13. Advances in shell side boiling of refrigerants

    NASA Astrophysics Data System (ADS)

    Webb, Ralph L.

    The design of shell and tube evaporators used in air conditioning and refrigeration applications is discussed. The heat exchanger geometry of interest involves evaporation or condensation on the shell side of a horizontal tube bundle. Enhanced heat transfer geometries are typically used for shell side evaporation and for forced convection to water on the tube side. Refrigerant boiling data and forced convection refrigerant boiling correlations are described. The refrigerants of interest include R-11, 12, 22, 123, and 134a. Thermal design methods for sizing of the evaporator and condenser are outlined. A computer model for prediction of the evaporator performance is described.

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

    PubMed

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

    2011-08-09

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

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

    PubMed Central

    2011-01-01

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

  16. Air Circulation and Heat Exchange Under Reduced Pressures

    NASA Technical Reports Server (NTRS)

    Rygalov, V.; Wheeler, R.; Dixon, M.; Fowler, P.; Hillhouse, L.

    2010-01-01

    Heat exchange rates decrease non-linearly with reductions in atmospheric pressure. This decrease creates risk of thermal stress (elevated leaf temperatures) for plants under reduced pressures. Forced convection (fans) significantly increases heat exchange rate under almost all pressures except below 10 kPa. Plant cultivation techniques under reduced pressures will require forced convection. The cooling curve technique is a reliable means of assessing the influence of environmental variables like pressure and gravity on gas exchange of plant. These results represent the extremes of gas exchange conditions for simple systems under variable pressures. In reality, dense plant canopies will exhibit responses in between these extremes. More research is needed to understand the dependence of forced convection on atmospheric pressure. The overall thermal balance model should include latent and radiative exchange components.

  17. The effect of different inlet conditions of air in a rectangular channel on convection heat transfer: Turbulence flow

    SciTech Connect

    Kurtbas, Irfan

    2008-10-15

    Theoretical and empirical correlations for duct flow are given for hydrodynamically and thermally developed flow in most of previous studies. However, this is commonly not a realistic inlet configuration for heat exchanger, in which coolant flow generally turns through a serpentine shaped passage before entering heat sinks. Accordingly, an experimental investigation was carried out to determine average heat transfer coefficients in uniformly heated rectangular channel with 45 and 90 turned flow, and with wall mounted a baffle. The channel was heated through bottom side with the baffle. In present work, a detailed study was conducted for three different height of entry channel (named as the ratio of the height of entry channel to the height of test section (anti H{sub c}=h{sub c}/H)) by varying Reynolds number (Re{sub Dh}). Another variable parameter was the ratio of the baffle height to the channel height (anti H{sub b}=h{sub b}/H). Only one baffle was attached on the bottom (heating) surface. The experimental procedure was validated by comparing the data for the straight channel with no baffle. Reynolds number (Re{sub Dh}) was varied from 2800 to 30,000, so the flow was considered as only turbulent regime. All experiments were conduced with air accordingly; Prandtl number (Pr) was approximately fixed at 0.71. The results showed that average Nusselt number for {theta}=45 and {theta}=90 were 9% and 30% higher, respectively, than that of the straight channel without baffle. Likewise, the pressure drop increased up to 4.4 to 5.3 times compare to the straight channel. (author)

  18. Experimental study on corrugated cross-flow air-cooled plate heat exchangers

    SciTech Connect

    Kim, Minsung; Baik, Young-Jin; Park, Seong-Ryong; Ra, Ho-Sang; Lim, Hyug

    2010-11-15

    Experimental study on cross-flow air-cooled plate heat exchangers (PHEs) was performed. The two prototype PHEs were manufactured in a stack of single-wave plates and double-wave plates in parallel. Cooling air flows through the PHEs in a crosswise direction against internal cooling water. The heat exchanger aims to substitute open-loop cooling towers with closed-loop water circulation, which guarantees cleanliness and compactness. In this study, the prototype PHEs were tested in a laboratory scale experiments. From the tests, double-wave PHE shows approximately 50% enhanced heat transfer performance compared to single-wave PHE. However, double-wave PHE costs 30% additional pressure drop. For commercialization, a wide channel design for air flow would be essential for reliable performance. (author)

  19. Air-liquid solar collector for solar heating, combined heating and cooling, and hot water subsystems

    NASA Technical Reports Server (NTRS)

    1978-01-01

    A collection of quarterly reports consisting of the installation and layout design of the air collector system for commercial applications, completion of the preliminary design review, detailed design efforts, and preparation of the verification test plan are given. Performance specifications and performance testing of a prototype model of a two manifold, 144 tube air collector array is presented.

  20. Heat transfer and pressure drop for air flow through enhanced passages. Final report

    SciTech Connect

    Obot, N.T.; Esen, E.B.

    1992-06-01

    An extensive experimental investigation was carried out to determine the pressure drop and heat transfer characteristics for laminar, transitional and turbulent flow of air through a smooth passage and twenty-three enhanced passages. The internal surfaces of all enhanced passages had spirally shaped geometries; these included fluted, finned/ribbed and indented surfaces. The Reynolds number (Re) was varied between 400 and 50000. The effect of heat transfer (wall cooling or fluid heating) on pressure drop is most significant within the transition region; the recorded pressure drop with heat transfer is much higher than that without heat transfer. The magnitude of this effect depends markedly on the average surface temperature and, to a lesser extent, on the geometric characteristics of the enhanced surfaces. When the pressure drop data are reduced as values of the Fanning friction factor(f), the results are about the same with and without heat transfer for turbulent flow, with moderate differences in the laminar and transition regions.

  1. Heat transfer and pressure drop for air flow through enhanced passages

    SciTech Connect

    Obot, N.T.; Esen, E.B.

    1992-06-01

    An extensive experimental investigation was carried out to determine the pressure drop and heat transfer characteristics for laminar, transitional and turbulent flow of air through a smooth passage and twenty-three enhanced passages. The internal surfaces of all enhanced passages had spirally shaped geometries; these included fluted, finned/ribbed and indented surfaces. The Reynolds number (Re) was varied between 400 and 50000. The effect of heat transfer (wall cooling or fluid heating) on pressure drop is most significant within the transition region; the recorded pressure drop with heat transfer is much higher than that without heat transfer. The magnitude of this effect depends markedly on the average surface temperature and, to a lesser extent, on the geometric characteristics of the enhanced surfaces. When the pressure drop data are reduced as values of the Fanning friction factor(f), the results are about the same with and without heat transfer for turbulent flow, with moderate differences in the laminar and transition regions.

  2. The relationship between radiant heat, air temperature and thermal comfort at rest and exercise.

    PubMed

    Guéritée, Julien; Tipton, Michael J

    2015-02-01

    The aims of the present work were to investigate the relationships between radiant heat load, air velocity and body temperatures with or without coincidental exercise to determine the physiological mechanisms that drive thermal comfort and thermoregulatory behaviour. Seven male volunteers wearing swimming trunks in 18°C, 22°C or 26°C air were exposed to increasing air velocities up to 3 m s(-1) and self-adjusted the intensity of the direct radiant heat received on the front of the body to just maintain overall thermal comfort, at rest or when cycling (60 W, 60 rpm). During the 30 min of the experiments, skin and rectal temperatures were continuously recorded. We hypothesized that mean body temperature should be maintained stable and the intensity of the radiant heat and the mean skin temperatures would be lower when cycling. In all conditions, mean body temperature was lower when facing winds of 3 m s(-1) than during the first 5 min, without wind. When facing winds, in all but the 26°C air, the radiant heat was statistically higher at rest than when exercising. In 26°C air mean skin temperature was lower at rest than when exercising. No other significant difference was observed. In all air temperatures, high correlation coefficients were observed between the air velocity and the radiant heat load. Other factors that we did not measure may have contributed to the constant overall thermal comfort status despite dropping mean skin and body temperatures. It is suggested that the allowance to behaviourally adjust the thermal environment increases the tolerance of cold discomfort.

  3. Method and apparatus for operating a self-starting air heating system

    DOEpatents

    Heinrich, Charles E.

    1983-12-06

    A self-starting, fuel fired, air heating system including a fuel burner fired vapor generator, a turbine, and a condenser connected in a closed circuit such that the vapor output from the vapor generator is conducted to the turbine and then to the condenser where it is condensed for return to the vapor generator. The turbine drives an air blower which passes air over the condenser for cooling the condenser and heating the air. Also, a condensate pump is driven by the turbine. The disclosure is particularly concerned with a method and apparatus which on start-up prevents the vapor generator's vapor output from being conducted to the turbine until a predetermined pressure differential has been achieved. However, after the vapor flow is once permitted, it cannot again be prevented until after the fuel burner has been shut off and restarted.

  4. Improved detection of low vapor pressure compounds in air by serial combination of single-sided membrane introduction with fiber introduction mass spectrometry (SS-MIMS-FIMS).

    PubMed

    Cotte-Rodríguez, Ismael; Handberg, Eric; Noll, Robert J; Kilgour, David P A; Cooks, R Graham

    2005-05-01

    The use of two methods in tandem, single-sided membrane introduction mass spectrometry (SS-MIMS) and fiber introduction mass spectrometry (FIMS), is presented as a technique for field analysis. The combined SS-MIMS-FIMS technique was employed in both a modified commercial mass spectrometer and a miniature mass spectrometer for the selective preconcentration of the explosive simulant o-nitrotoluene (ONT) and the chemical warfare agent simulant, methyl salicylate (MeS), in air. A home-built FIMS inlet was fabricated to allow introduction of the solid-phase microextraction (SPME) fiber into the mass spectrometer chamber and subsequent desorption of the trapped compounds using resistive heating. The SS-MIMS preconcentration system was also home-built from commercial vacuum parts. Optimization experiments were done separately for each preconcentration system to achieve the best extraction conditions prior to use of the two techniques in combination. Improved limits of detection, in the low ppb range, were observed for the combination compared to FIMS alone, using several SS-MIMS preconcentration cycles. The SS-MIMS-FIMS response for both instruments was found to be linear over the range 50 to 800 ppb. Other parameters studied were absorption time profiles, effects of sample flow rate, desorption temperature, fiber background, memory effects, and membrane fatigue. This simple, sensitive, accurate, robust, selective, and rapid sample preconcentration and introduction technique shows promise for field analysis of low vapor pressure compounds, where analyte concentrations will be extremely low and the compounds are difficult to extract from a matrix like air.

  5. Acoustical prediction methods for heating, ventilating, and air-conditioning (HVAC) systems

    NASA Astrophysics Data System (ADS)

    Ryherd, S. R.; Wang, L. M.

    2005-09-01

    The goal of this project is to compare and contrast various aspects of acoustical prediction methods for heating, ventilating, and air-conditioning (HVAC) systems. The three methods include two commonly used software programs and a custom spread sheet developed by the authors based on the American's Society of Heating, Refrigeration, and Air-conditioning Engineers (ASHRAE) Applications Handbook. Preliminary results indicate relatively good agreement between the three methods analyzed. The degree of disparity is predominately effected by the assumptions required by the end user. Research methods and results will be presented. This project provides a greater understanding of these acoustical prediction methods and their limitations.

  6. Preservation of Cognitive Performance with Age during Exertional Heat Stress under Low and High Air Velocity

    PubMed Central

    Wright Beatty, Heather E.; Keillor, Jocelyn M.; Hardcastle, Stephen G.; Boulay, Pierre; Kenny, Glen P.

    2015-01-01

    Older adults may be at greater risk for occupational injuries given their reduced capacity to dissipate heat, leading to greater thermal strain and potentially cognitive decrements. Purpose. To examine the effects of age and increased air velocity, during exercise in humid heat, on information processing and attention. Methods. Nine young (24 ± 1 years) and 9 older (59 ± 1 years) males cycled 4 × 15 min (separated by 15 min rest) at a fixed rate of heat production (400 W) in humid heat (35°C, 60% relative humidity) under 0.5 (low) and 3.0 (high) m·s−1 air velocity wearing coveralls. At rest, immediately following exercise (end exercise), and after the final recovery, participants performed an abbreviated paced auditory serial addition task (PASAT, 2 sec pace). Results. PASAT numbers of correct responses at end exercise were similar for young (low = 49 ± 3; high = 51 ± 3) and older (low = 46 ± 5; high = 47 ± 4) males and across air velocity conditions, and when scored relative to age norms. Psychological sweating, or an increased sweat rate with the administration of the PASAT, was observed in both age groups in the high condition. Conclusion. No significant decrements in attention and speeded information processing were observed, with age or altered air velocity, following intermittent exercise in humid heat. PMID:25874223

  7. Space Heating at the Naval Air Station, Fallon, Nevada - An Economic Analysis of a Geothermal Alternative.

    DTIC Science & Technology

    1979-12-01

    CLAWaICaTO ? I$ P iktfe bA& 8^100ŕ Approved for public release; distribution unlimited Space Heating at the Naval Air Station, Fallon, Nevada-An Economic...Dictionary of Geophysics, p . 981.)-------- 12 2. High temperature geothermal system flow controlled by fractures...Rome,21-31 Aug.1961,Vol.3, Geothermal Energy: 17 11, p .125.- ------------------------------------------------- 1 4. Map of Naval Air Station, Fallon

  8. Effectiveness of a municipal ground-coupled reversible heat pump system compared to an air-source system

    SciTech Connect

    Oerder, S.A.; Meyer, J.P.

    1998-10-01

    A municipal water network ground-coupled reversible heat pump was investigated as an alternative to conventional air-source heat pumps. It is projected that a system of this kind can be installed and operated at a lower cost than the commercially available systems. Models for the analysis of the ground-coupled reversible heat pump and conventional air-to-air systems were developed to evaluate the effectiveness of the ground-coupled system. The results indicate that this system can provide a cost-effective alternative to the more conventional air-to-air systems.

  9. Heat Exchange with Air and Temperature Profile of a Moving Oversize Tire

    NASA Astrophysics Data System (ADS)

    Grinchuk, P. S.; Fisenko, S. P.

    2016-11-01

    A one-dimensional mathematical model of heat transfer in a tire with account for the deformation energy dissipation and heat exchange of a moving tire with air has been developed. The mean temperature profiles are calculated and transition to a stationary thermal regime is considered. The influence of the rate of energy dissipation and of effective thermal conductivity of rubber on the temperature field is investigated quantitatively.

  10. The Effect of Aerodynamic Heating on Air Penetration by Shaped Charge Jets and Their Particles

    NASA Astrophysics Data System (ADS)

    Backofen, Joseph

    2009-06-01

    The goal of this paper is to present recent work modeling thermal coupling between shaped charge jets and their particles with air while it is being penetrated to form a crater that subsequently collapses back onto the jet. This work complements research published at International Symposia on Ballistics: 1) 1987 - Shaped Charge Jet Aerodynamics, Particulation and Blast Field Modeling; and 2) 2007 - Air Cratering by Eroding Shaped Charge Jets. The current work shows how and when a shaped charge jet's tip and jet particles are softened enough that they can erode in a hydrodynamic manner as modeled in these papers. This paper and its presentation includes models for heat transfer from shocked air as a function of jet velocity as well as heat flow within the jet or particle. The work is supported by an extensive bibliographic search including publications on meteors and ballistic missile re-entry vehicles. The modeling shows that a jet loses its strength to the depth required to justify hydrodynamic erosion when its velocity is above a specific velocity related to the shock properties of air and the jet material's properties. As a result, the portion of a jet's kinetic energy converted at the aerodynamic shock into heating transferred back onto the jet affects the energy deposited into the air through drag and ablation which in turn affect air crater expansion and subsequent collapse back onto the jet and its particles as shown in high-speed photography.

  11. Heat transfer characteristics of laminar methane/air flame impinging normal to a cylindrical surface

    SciTech Connect

    Chander, Subhash; Ray, Anjan

    2007-11-15

    An experimental study has been conducted to determine the heat transfer characteristics of methane/air laminar flames impinging normal to a cylindrical surface. Effects of variations in the values of Reynolds number (Re = 600-1300), equivalence ratio ({phi} = 0.8-1.3), dimensionless separation distance (H/d = 1-5), and burner diameter to cylinder diameter ratio (d/D = 0.0538-0.1076) have been investigated. Three important configurations, viz., flame inner reaction zone far away, just touching and intercepted by the impingement surface, were examined in detail. High stagnation point heat fluxes were obtained when tip of the flame inner reaction zone just touched the target surface. Stagnation point heat fluxes were either zero or negative when the inner reaction zone was intercepted by the impingement surface. An off-stagnation peak in heat flux was obtained at moderate separation distances above the flame tip. Both stagnation point and peak heat fluxes increased with Re when the inner reaction zone length was less than the separation distance. Heat fluxes in the wall-jet region were high at high Re. Maximum heat fluxes were obtained for initially fuel-rich mixture conditions due to entrainment of the surrounding air. Smaller burner diameters produced high heat flux at the stagnation region for fixed Reynolds number and opposite trends were seen in the wall-jet region. A secondary rise in stagnation point heat flux was obtained at larger separation distances. This secondary rise in heat flux was quite significant for larger burner diameters and at low flow rates. Correlations were developed for stagnation point heat flux. Results were also compared with flat plate under identical operating conditions. (author)

  12. Two-dimensional model of the air flow and temperature distribution in a cavity-type heat receiver of a solar stirling engine

    SciTech Connect

    Makhkamov, K.K.; Ingham, D.B.

    1999-11-01

    A theoretical study on the air flow and temperature in the heat receiver, affected by free convection, of a Stirling Engine for a Dish/Stirling Engine Power System is presented. The standard {kappa}-{epsilon} turbulence model for the fluid flow has been used and the boundary conditions employed were obtained using a second level mathematical model of the Stirling Engine working cycle. Physical models for the distribution of the solar insolation from the Concentrator on the bottom and side walls of the cavity-type heat receiver have been taken into account. The numerical results show that most of the heat losses in the receiver are due to re-radiation from the cavity and conduction through the walls of the cavity. It is in the region of the boundary of the input window of the heat receiver where there is a sensible reduction in the temperature in the shell of the heat exchangers and this is due to the free convection of the air. Further, the numerical results show that convective heat losses increase with decreasing tilt angle.

  13. Measurement of convective heat transfer coefficient for a horizontal cylinder rotating in quiescent air

    SciTech Connect

    Oezerdem, B.

    2000-04-01

    Heat transfer from a rotating cylinder is one of the problems, which is drawing attention due to its wide range of engineering applications. The present paper deals with convective heat transfer from a horizontal cylinder rotating in quiescent air, experimentally. The average convective heat transfer coefficients have been measured by using radiation pyrometer, which offers a new method. According to the experimental results, a correlation in terms of the average Nusselt number and rotating Reynolds number has been established. The average Nusselt number increased with an increase in the rotating speed. Comparison of the results, with previous studies, have been showed a good agreement with each other.

  14. Physiological and subjective responses in the elderly when using floor heating and air conditioning systems.

    PubMed

    Hashiguchi, Nobuko; Tochihara, Yutaka; Ohnaka, Tadakatsu; Tsuchida, Chiaki; Otsuki, Tamio

    2004-11-01

    The purpose of this study was to investigate the effects of a floor heating and air conditioning system on thermal responses of the elderly. Eight elderly men and eight university students sat for 90 minutes in a chair under the following 3 conditions: air conditioning system (A), floor heating system (F) and no heating system (C). The air temperature of sitting head height for condition A was 25 degrees C, and the maximum difference in vertical air temperature was 4 degrees C. The air and floor temperature for condition F were 21 and 29 degrees C, respectively. The air temperature for condition C was 15 degrees C. There were no significant differences in rectal temperature and mean skin temperature between condition A and F. Systolic blood pressure of the elderly men in condition C significantly increased compared to those in condition A and F. No significant differences in systolic blood pressure between condition A and F were found. The percentage of subjects who felt comfortable under condition F was higher than that of those under condition A in both age groups, though the differences between condition F and A was not significant. Relationships between thermal comfort and peripheral (e.g., instep, calf, hand) skin temperature, and the relationship between thermal comfort and leg thermal sensation were significant for both age groups. However, the back and chest skin temperature and back thermal sensation for the elderly, in contrast to that for the young, was not significantly related to thermal comfort. These findings suggested that thermal responses and physiological strain using the floor heating system did not significantly differ from that using the air conditioning system, regardless of the subject age and despite the fact that the air temperature with the floor heating system was lower. An increase in BP for elderly was observed under the condition in which the air temperature was 15 degrees C, and it was suggested that it was necessary for the elderly

  15. Experimental study of the heat transfer process of air around atmospheric arc plasma

    NASA Astrophysics Data System (ADS)

    Salimi Meidanshahi, F.; Madanipour, Kh.; Shokri, Babak

    2011-05-01

    The experimental investigation of thermodynamic properties such heat and mass transfer of plasmas has many applications in different industries. Laboratory atmospheric arc plasma is studied in this work. The refractive index of the air around the plasma is changed because of convection phenomena. When the convection creates the air flowing around the plasma, the density and consequently, the refractive index of air are distributed symmetrically. Moiré deflectometry is a technique of wave front analysis which in both Talbot effect and moiré technique is applied for measuring phase objects. Deflection of light beam passing through the inhomogeneous medium is utilized to obtain the refractive index distribution. In experimental set-up, an expanded collimated He-Ne laser propagate through the arc plasma and the around air. The temperature distribution is obtained by use of thermo-optic coefficient of air. To calculate the thermo- optic coefficient and the refractive index of air for a given wavelength of light and given atmospheric conditions (air temperature, pressure, and humidity), the Edlén equation is used. The convective heat transfer coefficient is obtained by calculating the temperature gradient on the plasma border. This method is not expensive, complicated and sensitive to environmental vibrations.

  16. Development of a High Performance Air Source Heat Pump for the US Market

    SciTech Connect

    Abdelaziz, Omar; Shen, Bo; Gao, Zhiming; Baxter, Van D; Iu, Ipseng

    2011-01-01

    Heat pumps present a significant advantage over conventional residential heating technologies due to higher energy efficiencies and less dependence on imported oil. The US development of heat pumps dates back to the 1930 s with pilot units being commercially available in the 1950 s. Reliable and cost competitive units were available in the US market by the 1960 s. The 1973 oil embargo led to increased interest in heat pumps prompting significant research to improve performance, particularly for cold climate locations. Recent increasing concerns on building energy efficiency and environmental emissions have prompted a new wave of research in heat pump technology with special emphasis on reducing performance degradation at colder outdoor air temperatures. A summary of the advantages and limitations of several performance improvement options sought for the development of high performance air source heat pump systems for cold climate applications is the primary focus of this paper. Some recommendations for a high performance cold climate heat pump system design most suitable for the US market are presented.

  17. Heat-tolerant rice cultivars retain grain appearance quality under free-air CO2 enrichment

    PubMed Central

    2014-01-01

    Background Heat-tolerant rice cultivars have been developed as a countermeasure to poor grain appearance quality under high temperatures. Recent studies showed that elevated CO2 concentrations (E-[CO2]) also reduce grain quality. To determine whether heat-tolerant cultivars also tolerate E-[CO2], we conducted a free-air CO2 enrichment (FACE) experiment with 12 rice cultivars differing in heat tolerance. Results The percentage of undamaged grains of five standard cultivars (Akitakomachi, Kinuhikari, Koshihikari, Matsuribare, Nipponbare) averaged 61.7% in the ambient [CO2] (AMB) plot and 51.7% in the FACE plot, whereas that of heat-tolerant cultivars (Eminokizuna, Wa2398, Kanto 257, Toyama 80, Mineharuka, Kanto 259, Saikai 290) averaged 73.5% in AMB and 71.3% in FACE. This resulted in a significant [CO2] by cultivar interaction. The percentage of white-base or white-back grains increased from 8.4% in AMB to 17.1% in FACE in the sensitive cultivars, but from only 2.1% in AMB to only 4.4% in FACE in the heat-tolerant cultivars. Conclusion Heat-tolerant cultivars retained their grain appearance quality at E-[CO2] under present air temperatures. Further improvements in appearance quality under present conditions will be needed to achieve improvements under E-[CO2], because E-[CO2] will likely lower the threshold temperature for heat stress. PMID:24920972

  18. Performance Analysis of Air-to-Water Heat Pump in Latvian Climate Conditions

    NASA Astrophysics Data System (ADS)

    Kazjonovs, Janis; Sipkevics, Andrejs; Jakovics, Andris; Dancigs, Andris; Bajare, Diana; Dancigs, Leonards

    2014-12-01

    Strategy of the European Union in efficient energy usage demands to have a higher proportion of renewable energy in the energy market. Since heat pumps are considered to be one of the most efficient heating and cooling systems, they will play an important role in the energy consumption reduction in buildings aimed to meet the target of nearly zero energy buildings set out in the EU Directive 2010/31/EU. Unfortunately, the declared heat pump Coefficient of Performance (COP) corresponds to a certain outdoor temperature (+7 °C), therefore different climate conditions, building characteristics and settings result in different COP values during the year. The aim of this research is to investigate the Seasonal Performance factor (SPF) values of air-to-water heat pump which better characterize the effectiveness of heat pump in a longer selected period of time, especially during the winter season, in different types of residential buildings in Latvian climate conditions. Latvia has four pronounced seasons of near-equal length. Winter starts in mid-December and lasts until mid-March. Latvia is characterized by cold, maritime climate (duration of the average heating period being 203 days, the average outdoor air temperature during the heating period being 0.0 °C, the coldest five-day average temperature being -20.7 °C, the average annual air temperature being +6.2 °C, the daily average relative humidity being 79 %). The first part of this research consists of operational air-towater heat pump energy performance monitoring in different residential buildings during the winter season. The second part of the research takes place under natural conditions in an experimental construction stand which is located in an urban environment in Riga, Latvia. The inner area of this test stand, where air-to-water heat pump performance is analyzed, is 9 m2. The ceiling height is 3 m, all external wall constructions (U = 0.16 W/(m2K)) have ventilated facades. To calculate SPF, the

  19. Multiple source heat pump

    DOEpatents

    Ecker, Amir L.

    1983-01-01

    A heat pump apparatus for conditioning a fluid characterized by a fluid handler and path for circulating a fluid in heat exchange relationship with a refrigerant fluid, at least three refrigerant heat exchangers, one for effecting heat exchange with the fluid, a second for effecting heat exchange with a heat exchange fluid, and a third for effecting heat exchange with ambient air; a compressor for compressing the refrigerant; at least one throttling valve connected at the inlet side of a heat exchanger in which liquid refrigerant is vaporized; a refrigerant circuit; refrigerant; a source of heat exchange fluid; heat exchange fluid circuit and pump for circulating the heat exchange fluid in heat exchange relationship with the refrigerant; and valves or switches for selecting the heat exchangers and directional flow of refrigerant therethrough for selecting a particular mode of operation. Also disclosed are a variety of embodiments, modes of operation, and schematics therefor.

  20. Geothermal as a heat sink application for raising air conditioning efficency

    NASA Astrophysics Data System (ADS)

    Ibrahim, Hesham Safwat Osman Mohamed

    2016-04-01

    Objective: Geothermal applications in heating, ventilation, air-conditioning is a US technology for more than 30 years old ,which saves more than 30% average energy cost than the traditional air-conditioning systems systems. Applying this technology in Middle East and African countries would be very feasible specially in Egypt specially as it suffers Electric crisis --The temperature of the condensers and the heat rejecting equipment is much higher than the Egyptian land at different depth which is a great advantages, and must be measured, recorded, and studied accurately -The Far goal of the proposal is to construct from soil analysis a temperature gradient map for Egypt and , African countries on different depth till 100 m which is still unclear nowadays and must be measured and recorded in databases through researches - The main model of the research is to study the heat transfer gradient through the ground earth borehole,grout,high density polyethylene pipes , and water inlet temperature which affect the electric efficiency of the ground source heat pump air conditioning unit Impact on the Region: Such research result will contribute widely in Energy saving sector specially the air conditioning sector in Egypt and the African countries which consumes more than 30% of the electric consumption of the total consumption . and encouraging Green systems such Geothermal to be applied

  1. Heating, Air Conditioning and Refrigeration. Vocational Education Curriculum Guide. Industrial and Technical Education.

    ERIC Educational Resources Information Center

    West Virginia State Vocational Curriculum Lab., Cedar Lakes.

    This curriculum guide contains 17 units that provides the basic curriculum components required to develop lesson plans for the heating, air conditioning, and refrigeration curriculum. The guide is not intended to be a complete, self-contained curriculum, but instead provides the teacher with a number of informational items related to the learning…

  2. Technology evaluation of heating, ventilation, and air conditioning for MIUS application

    NASA Technical Reports Server (NTRS)

    Gill, W. L.; Keough, M. B.; Rippey, J. O.

    1974-01-01

    Potential ways of providing heating, ventilation, and air conditioning for a building complex serviced by a modular integrated utility system (MIUS) are examined. Literature surveys were conducted to investigate both conventional and unusual systems to serve this purpose. The advantages and disadvantages of the systems most compatible with MIUS are discussed.

  3. DEVELOPMENT OF A LINEAR COMPRESSOR FOR AIR CONDITIONERS AND HEAT PUMPS

    EPA Science Inventory

    The report discusses the design, building, testing, and delivering to the Environmental Protection Agency of a linear compressor for operation in a 3.0- ton (10.5 kW) residential air-conditioning and heat pumping system. The compressor design evolved from a linear resonant piston...

  4. Introduction to Heating, Ventilation and Air Conditioning (HVAC). Instructor Edition. Introduction to Construction Series.

    ERIC Educational Resources Information Center

    Oklahoma State Dept. of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    This instructor's guide contains the materials required to teach a competency-based introductory course in heating, ventilating, and air conditioning (HVAC) to students who have chosen to explore careers in construction. It contains three units: HVAC materials, HVAC tools, and applied skills. Each instructional unit includes some or all of the…

  5. Introduction to Heating, Ventilation and Air Conditioning (HVAC). Introduction to Construction Series. Instructor Edition.

    ERIC Educational Resources Information Center

    Associated General Contractors of America, Washington, DC.

    This module on introductory heating, ventilating, and air conditioning (HVAC) is one of a series of modules designed to teach basic skills necessary for entry-level employment in this field. The module contains four instructional units that cover the following topics: (1) HVAC materials; (2) HVAC tools; (3) HVAC layout; and (4) HVAC basic skills.…

  6. VESL for Heating and Air Conditioning: A Competency-based Curriculum Guide. Project OSCAER.

    ERIC Educational Resources Information Center

    Lopez-Valadez, Jeanne, Ed.; Pankratz, David, Ed.

    This guide is intended for vocational educators developing the vocational English as a second language (VESL) component of a course in heating and air conditioning. The introductory section examines assumptions about second language learning and instruction and VESL classes, local adaptations of the curriculum, and sample VESL lessons. The chapter…

  7. 10 CFR 429.43 - Commercial heating, ventilating, air conditioning (HVAC) equipment.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... ensure that— (i) Any represented value of energy consumption or other measure of energy usage of a basic... 10 Energy 3 2012-01-01 2012-01-01 false Commercial heating, ventilating, air conditioning (HVAC) equipment. 429.43 Section 429.43 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION CERTIFICATION,...

  8. 10 CFR 429.43 - Commercial heating, ventilating, air conditioning (HVAC) equipment.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... ensure that— (i) Any represented value of energy consumption or other measure of energy usage of a basic... 10 Energy 3 2013-01-01 2013-01-01 false Commercial heating, ventilating, air conditioning (HVAC) equipment. 429.43 Section 429.43 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION CERTIFICATION,...

  9. 10 CFR 429.43 - Commercial heating, ventilating, air conditioning (HVAC) equipment.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... of energy consumption or other measure of energy usage of a basic model for which consumers would... 10 Energy 3 2014-01-01 2014-01-01 false Commercial heating, ventilating, air conditioning (HVAC) equipment. 429.43 Section 429.43 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION CERTIFICATION,...

  10. 16 CFR 305.12 - Labeling for central air conditioners, heat pumps, and furnaces.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... pumps, and furnaces. 305.12 Section 305.12 Commercial Practices FEDERAL TRADE COMMISSION REGULATIONS... pumps, and furnaces. (a) Layout. All energy labels for central air conditioners, heat pumps, and furnaces (including boilers) shall use one size, similar colors, and typefaces with consistent...

  11. 16 CFR 305.12 - Labeling for central air conditioners, heat pumps, and furnaces.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... pumps, and furnaces. 305.12 Section 305.12 Commercial Practices FEDERAL TRADE COMMISSION REGULATIONS... pumps, and furnaces. (a) Layout. All energy labels for central air conditioners, heat pumps, and furnaces (including boilers) shall use one size, similar colors, and typefaces with consistent...

  12. 16 CFR 305.12 - Labeling for central air conditioners, heat pumps, and furnaces.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... pumps, and furnaces. 305.12 Section 305.12 Commercial Practices FEDERAL TRADE COMMISSION REGULATIONS... pumps, and furnaces. (a) Layout. All energy labels for central air conditioners, heat pumps, and furnaces (including boilers) shall use one size, similar colors, and typefaces with consistent...

  13. 16 CFR 305.12 - Labeling for central air conditioners, heat pumps, and furnaces.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... pumps, and furnaces. 305.12 Section 305.12 Commercial Practices FEDERAL TRADE COMMISSION REGULATIONS... pumps, and furnaces. (a) Layout. All energy labels for central air conditioners, heat pumps, and furnaces (including boilers) shall use one size, similar colors, and typefaces with consistent...

  14. Getting Down to Business: Air Conditioning and Heating Service, Module 36. Teacher Guide. Entrepreneurship Training Components.

    ERIC Educational Resources Information Center

    Sanderson, Barbara

    This is the thirty-sixth in a set of 36 teacher guides to the Entrepreneurial Training Modules and accompanies CE 031 100. The purpose of the module is to give students some idea of what it is like to own and operate an air conditioning and heating service. Following an overview are general notes on use of the module. Suggested steps for module…

  15. Heating, Air Conditioning and Refrigeration Curriculum Guide. Michigan Trade and Industrial Education.

    ERIC Educational Resources Information Center

    Michigan State Univ., East Lansing. Coll. of Agriculture and Natural Resources Education Inst.

    This task-based curriculum guide for heating, air conditioning, and refrigeration is intended to help the teacher develop a classroom management system where students learn by doing. Introductory materials include a Dictionary of Occupational Titles job code and title sheet, a career ladder, a matrix relating duty/task numbers to job titles, and a…

  16. Heating, Ventilation, Air Conditioning. Resource Manual for Custodial Training Course #3.

    ERIC Educational Resources Information Center

    Florida State Dept. of Education, Tallahassee. School Plant Management Section.

    Intended as a manual to provide school custodians with some understanding of basic functions of heating, ventilating, and air conditioning equipment for safe, efficient operation. Contains general rules and specifications for providing custodians with a more complete awareness of their equipment and the field of "Climate Control" within the…

  17. 10 CFR 431.92 - Definitions concerning commercial air conditioners and heat pumps.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... heat pumps. 431.92 Section 431.92 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY EFFICIENCY... that affect energy consumption, energy efficiency, water consumption, or water efficiency. Coefficient... humidity control of the supplied air, and reheating function. Energy Efficiency Ratio, or EER means...

  18. Heating, Ventilation, Air-conditioning, and Refrigeration. Ohio's Competency Analysis Profile.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. Vocational Instructional Materials Lab.

    Developed through a modified DACUM (Developing a Curriculum) process involving business, industry, labor, and community agency representatives in Ohio, this document is a comprehensive and verified employer competency profile for heating, ventilation, air conditioning, and refrigeration occupations. The list contains units (with and without…

  19. Getting Down to Business: Air Conditioning and Heating Service, Module 36. [Student Guide]. Entrepreneurship Training Components.

    ERIC Educational Resources Information Center

    Sanderson, Barbara

    This module on owning and operating an air conditioning and heating service is one of 36 in a series on entrepreneurship. The introduction tells the student what topics will be covered and suggests other modules to read in related occupations. Each unit includes student goals, a case study, and a discussion of the unit subject matter. Learning…

  20. Air-sea heat exchange, an element of the water cycle

    NASA Technical Reports Server (NTRS)

    Chahine, M. T.

    1984-01-01

    The distribution and variation of water vapor, clouds and precipitation are examined. Principal driving forces for these distributions are energy exchange and evaporation at the air-sea interface, which are also important elements of air-sea interaction studies. The overall aim of air-sea interaction studies is to quantitatively determine mass, momentum and energy fluxes, with the goal of understanding the mechanisms controlling them. The results of general circulation simulations indicate that the atmosphere in mid-latitudes responds to changes in the oceanic surface conditions in the tropics. This correlation reflects the strong interaction between tropical and mid-latitude conditions caused by the transport of heat and momentum from the tropics. Studies of air-sea exchanges involve a large number of physica, chemical and dynamical processes including heat flux, radiation, sea-surface temperature, precipitation, winds and ocean currents. The fluxes of latent heat are studied and the potential use of satellite data in determining them evaluated. Alternative ways of inferring heat fluxes will be considered.

  1. Improved Modeling of Residential Air Conditioners and Heat Pumps for Energy Calculations

    SciTech Connect

    Cutler, D.; Winkler, J.; Kruis, N.; Christensen, C.; Brandemuehl, M.

    2013-01-01

    This report presents improved air conditioner and heat pump modeling methods in the context of whole-building simulation tools, with the goal of enabling more accurate evaluation of cost-effective equipment upgrade opportunities and efficiency improvements in residential buildings.

  2. Heat Dissipation from a Finned Cylinder at Different Fin-Plane/Air-stream Angles

    NASA Technical Reports Server (NTRS)

    Schey, Oscar W; Biermann, Arnold E

    1932-01-01

    This report gives the results of an experimental determination of the temperature distribution in and the heat dissipation from a cylindrical finned surface for various fin-plane/air-stream angles. A steel cylinder 4.5 inches in diameter having slightly tapered fins of 0.30-inch pitch and 0.6 -inch width was equipped with an electrical heating unit furnishing 13 to 248 B.T.U. per hour per square inch of inside wall area. Air at speeds form 30 to 150 miles per hour was directed at seven different angles from 0 degrees to 90 degrees with respect to the fin planes. The tests show the best angle for cooling at all air speeds to be about 45 degrees. With the same temperature for the two conditions and with an air speed of 76 miles per hour, the heat input to the cylinder can be increased 50 percent at 45 degrees fin-plane/air-stream angle over that at 0 degrees.

  3. Velocity and temperature field characteristics of water and air during natural convection heating in cans.

    PubMed

    Erdogdu, Ferruh; Tutar, Mustafa

    2011-01-01

    Presence of headspace during canning is required since an adequate amount allows forming vacuum during the process. Sealing technology may not totally eliminate all entrapped gases, and headspace might affect heat transfer. Not much attention has been given to solve this problem in computational studies, and cans, for example, were mostly assumed to be fully filled with product. Therefore, the objective of this study was to determine velocity and temperature evolution of water and air in cans during heating to evaluate the relevance of headspace in the transport mechanism. For this purpose, canned water samples with a certain headspace were used, and required governing continuity, energy, and momentum equations were solved using a finite volume approach coupled with a volume of fluid element model. Simulation results correlated well with experimental results validating faster heating effects of headspace rather than insulation effects as reported in the literature. The organized velocity motions along the air-water interface were also shown. Practical Application: Canning is a universal and economic method for processing of food products, and presence of adequate headspace is required to form vacuum during sealing of the cans. Since sealing technology may not totally eliminate the entrapped gases, mainly air, headspace might affect heating rates in cans. This study demonstrated the increased heating rates in the presence of headspace in contrast with some studies in the literature. By applying the effect of headspace, required processing time for thermally processed foods can be reduced leading to more rapid processes and lower energy consumptions.

  4. Performance enhancement of an experimental air conditioning system by using TiO2/methanol nanofluid in heat pipe heat exchangers

    NASA Astrophysics Data System (ADS)

    Monirimanesh, Negin; Nowee, S. Mostafa; Khayyami, Shideh; Abrishamchi, Iman

    2016-05-01

    The effect of using nanofluid in thermosyphon-type heat pipe heat exchangers on energy conservation of an air-conditioning system was sought in this study. Innovatively, two heat exchangers in-series were deployed using TiO2/methanol nanofluids with 0-4 wt% concentrations as working fluids. The impacts of temperature and relative humidity on the effectiveness of 2 and 4-row heat exchangers were analyzed experimentally and more that 40 % energy saving was obtained.

  5. Experimental study of heat transfer and thermal performance with longitudinal fins of solar air heater

    PubMed Central

    Chabane, Foued; Moummi, Noureddine; Benramache, Said

    2013-01-01

    The thermal performance of a single pass solar air heater with five fins attached was investigated experimentally. Longitudinal fins were used inferior the absorber plate to increase the heat exchange and render the flow fluid in the channel uniform. The effect of mass flow rate of air on the outlet temperature, the heat transfer in the thickness of the solar collector, and the thermal efficiency were studied. Experiments were performed for two air mass flow rates of 0.012 and 0.016 kg s−1. Moreover, the maximum efficiency values obtained for the 0.012 and 0.016 kg s−1 with and without fins were 40.02%, 51.50% and 34.92%, 43.94%, respectively. A comparison of the results of the mass flow rates by solar collector with and without fins shows a substantial enhancement in the thermal efficiency. PMID:25685486

  6. Experimental study of heat transfer and thermal performance with longitudinal fins of solar air heater.

    PubMed

    Chabane, Foued; Moummi, Noureddine; Benramache, Said

    2014-03-01

    The thermal performance of a single pass solar air heater with five fins attached was investigated experimentally. Longitudinal fins were used inferior the absorber plate to increase the heat exchange and render the flow fluid in the channel uniform. The effect of mass flow rate of air on the outlet temperature, the heat transfer in the thickness of the solar collector, and the thermal efficiency were studied. Experiments were performed for two air mass flow rates of 0.012 and 0.016 kg s(-1). Moreover, the maximum efficiency values obtained for the 0.012 and 0.016 kg s(-1) with and without fins were 40.02%, 51.50% and 34.92%, 43.94%, respectively. A comparison of the results of the mass flow rates by solar collector with and without fins shows a substantial enhancement in the thermal efficiency.

  7. Free convectively induced air intrusion effects on heat transfer through porous insulation

    NASA Astrophysics Data System (ADS)

    Jaung, R.

    1981-08-01

    The thermal resistance of porous thermal insulation is investigated. A 4.0 ft. by 5.0 ft. double heat transfer gage test apparatus is employed to study the thermal performance of a sandwich-type insulator system quantitatively. Heat transfer through porous medium without free convectively induced air intrusion effects is also investigated. Boundary emissivity effects and cellularization effects are studied to understand the role of radiative heat transfer. Various arrangements of nonpermeable and semipermeable membranes were inserted at the air insulator interface to improve its performance. Incompressible fluid dynamic equations describing the convective flow are analyzed and approximated using finite difference methods. The thermal boundary layer is studied experimentally. Interferometric experimental results are qualitatively agreed with the numerical solutions. It is shown that the installation of interfacial barriers upgrade the thermal performance of sandwich insulation.

  8. Heat transfer properties, moisture loss, product yield, and soluble proteins in chicken breast patties during air convection cooking.

    PubMed

    Murphy, R Y; Johnson, E R; Duncan, L K; Clausen, E C; Davis, M D; March, J A

    2001-04-01

    Chicken breast patties were processed in an air convection oven at air temperatures of 149 to 218 C, air velocities of 7.1 to 12.7 m3/min, and air relative humidities of 40 to 95%. The air humidity was controlled via introducing steam into the oven. The patties were processed to a final center temperature of 50 to 80 C. Heat flux, heat transfer coefficient, moisture loss in the cooked chicken patties, the product yield, and the changes of soluble proteins in the product were evaluated for the cooking system. During cooking, heat flux varied with the processing time. Heat flux increased with increasing air humidity. The effective heat transfer coefficient was obtained for different cooking conditions. Air humidity in the oven affected the heat transfer coefficient. The moisture loss in the cooked products increased with increasing the final product temperature and the oven air temperature. The soluble proteins in the cooked patties decreased with increasing the final product temperature. Increasing humidity increased heat transfer coefficient and therefore reduced cooking time. Reducing oven temperature, reducing internal temperature, and increasing air humidity increased the product yield. Soluble proteins might be used as an indicator for the degree of cooking. The results from this study are important for evaluating commercial thermal processes and improving product yields.

  9. Waking the sleeping giant: Introducing new heat exchanger technology into the residential air-conditioning marketplace

    SciTech Connect

    Chapp, T.; Voss, M.; Stephens, C.

    1998-07-01

    The Air Conditioning Industry has made tremendous strides in improvements to the energy efficiency and reliability of its product offerings over the past 40 years. These improvement can be attributed to enhancements of components, optimization of the energy cycle, and modernized and refined manufacturing techniques. During this same period, energy consumption for space cooling has grown significantly. In January of 1992, the minimum efficiency requirement for central air conditioning equipment was raised to 10 SEER. This efficiency level is likely to increase further under the auspices of the National Appliance Energy Conservation Act (NAECA). A new type of heat exchanger was developed for air conditioning equipment by Modine Manufacturing Company in the early 1990's. Despite significant advantages in terms of energy efficiency, dehumidification, durability, and refrigerant charge there has been little interest expressed by the air conditioning industry. A cooperative effort between Modine, various utilities, and several state energy offices has been organized to test and demonstrate the viability of this heat exchanger design throughout the nation. This paper will review the fundamentals of heat exchanger design and document this simple, yet novel technology. These experiences involving equipment retrofits have been documented with respect to the performance potential of air conditioning system constructed with PF{trademark} Heat Exchangers (generically referred to as microchannel heat exchangers) from both an energy efficiency as well as a comfort perspective. The paper will also detail the current plan to introduce 16 to 24 systems into an extended field test throughout the US which commenced in the Fall of 1997.

  10. Combined facial heating and inhalation of hot air do not alter thermoeffector responses in humans

    PubMed Central

    Wingo, Jonathan E.; Low, David A.; Keller, David M.; Kimura, Kenichi

    2015-01-01

    The influence of thermoreceptors in human facial skin on thermoeffector responses is equivocal; furthermore, the presence of thermoreceptors in the respiratory tract and their involvement in thermal homeostasis has not been elucidated. This study tested the hypothesis that hot air directed on the face and inhaled during whole body passive heat stress elicits an earlier onset and greater sensitivity of cutaneous vasodilation and sweating than that directed on an equal skin surface area away from the face. Six men and two women completed two trials separated by ∼1 wk. Participants were passively heated (water-perfused suit; core temperature increase ∼0.9°C) while hot air was directed on either the face or on the lower leg (counterbalanced). Skin blood flux (laser-Doppler flowmetry) and local sweat rate (capacitance hygrometry) were measured at the chest and one forearm. During hot-air heating, local temperatures of the cheek and leg were 38.4 ± 0.8°C and 38.8 ± 0.6°C, respectively (P = 0.18). Breathing hot air combined with facial heating did not affect mean body temperature onsets (P = 0.97 and 0.27 for arm and chest sites, respectively) or slopes of cutaneous vasodilation (P = 0.49 and 0.43 for arm and chest sites, respectively), or the onsets (P = 0.89 and 0.94 for arm and chest sites, respectively), or slopes of sweating (P = 0.48 and 0.65 for arm and chest sites, respectively). Based on these findings, respiratory tract thermoreceptors, if present in humans, and selective facial skin heating do not modulate thermoeffector responses during passive heat stress. PMID:26157054

  11. Combined facial heating and inhalation of hot air do not alter thermoeffector responses in humans.

    PubMed

    Wingo, Jonathan E; Low, David A; Keller, David M; Kimura, Kenichi; Crandall, Craig G

    2015-09-01

    The influence of thermoreceptors in human facial skin on thermoeffector responses is equivocal; furthermore, the presence of thermoreceptors in the respiratory tract and their involvement in thermal homeostasis has not been elucidated. This study tested the hypothesis that hot air directed on the face and inhaled during whole body passive heat stress elicits an earlier onset and greater sensitivity of cutaneous vasodilation and sweating than that directed on an equal skin surface area away from the face. Six men and two women completed two trials separated by ∼1 wk. Participants were passively heated (water-perfused suit; core temperature increase ∼0.9°C) while hot air was directed on either the face or on the lower leg (counterbalanced). Skin blood flux (laser-Doppler flowmetry) and local sweat rate (capacitance hygrometry) were measured at the chest and one forearm. During hot-air heating, local temperatures of the cheek and leg were 38.4 ± 0.8°C and 38.8 ± 0.6°C, respectively (P = 0.18). Breathing hot air combined with facial heating did not affect mean body temperature onsets (P = 0.97 and 0.27 for arm and chest sites, respectively) or slopes of cutaneous vasodilation (P = 0.49 and 0.43 for arm and chest sites, respectively), or the onsets (P = 0.89 and 0.94 for arm and chest sites, respectively), or slopes of sweating (P = 0.48 and 0.65 for arm and chest sites, respectively). Based on these findings, respiratory tract thermoreceptors, if present in humans, and selective facial skin heating do not modulate thermoeffector responses during passive heat stress.

  12. Local mean age measurements for heating, cooling, and isothermal supply air conditions

    SciTech Connect

    Han, H.; Kuehn, T.H.; Kim, Y.

    1999-07-01

    The objective of this paper is to investigate the effect on room ventilation of thermal buoyancy caused by temperature differences between surfaces and the supply air. Spatial distributions of local mean age were obtained in a half-scale environmental chamber under well-controlled temperature conditions simulating isothermal ventilation, cooling, and heating. Air was supplied and returned through slots in the ceiling. Sulfur hexafluoride (SF{sub 6}) tracer gas concentration was measured by an electron capture gas chromatograph. Tracer gas concentration was measured at various points in the chamber versus time after a pulse injection was applied in the supply air duct. The maximum local mean age (LMA) was obtained near the center of a large recirculation zone for isothermal conditions. The results for cooling conditions showed a relatively uniform LMA distribution in the space compared to the isothermal conditions, as the room air was well mixed by the cold downdraft from the supply. However, there was a large variation in local air change indices in the space for the heating condition because of stable thermal stratification. Warm supply air could not penetrate into the lower half of the space but short-circuited to the exhaust duct. The model results in the present study can be converted to full-scale situations using similitude and can be used for validating computational fluid dynamics codes.

  13. Air quality influenced by urban heat island coupled with synoptic weather patterns.

    PubMed

    Lai, Li-Wei; Cheng, Wan-Li

    2009-04-01

    Few studies have discussed the association between the urban heat island (UHI) phenomenon and air quality under synoptic weather patterns conducive to UHI. In this study, the authors used statistical analyses to study this association in the Taichung metropolis region. The air quality data obtained from government-owned observation stations and wind field profiles obtained from tethersonde monitoring (performed during 21-29 October 2004) were combined with the simulations of the horizontal wind fields at different heights by the air pollution model (TAPM). The results show that certain specific synoptic weather patterns worsen the air quality and induce the UHI phenomenon: Taichung's UHI appears clearly under the synoptic weather patterns featuring light air or breezes (0.56 m/s < or =wind speed <2.2 m/s) mainly from the north and west. Furthermore, under these weather patterns, the concentrations of air pollutants (NO2, CO2 and CO) increase significantly (P<0.05) with the UHI intensity. The convergence usually associated with nocturnal UHI causes the accumulation of O3 precursors, as well as other air pollutants, thereby worsening the air quality at that time and also during the following daytime period.

  14. Robustness analysis of an air heating plant and control law by using polynomial chaos

    SciTech Connect

    Colón, Diego; Ferreira, Murillo A. S.; Bueno, Átila M.; Balthazar, José M.; Rosa, Suélia S. R. F. de

    2014-12-10

    This paper presents a robustness analysis of an air heating plant with a multivariable closed-loop control law by using the polynomial chaos methodology (MPC). The plant consists of a PVC tube with a fan in the air input (that forces the air through the tube) and a mass flux sensor in the output. A heating resistance warms the air as it flows inside the tube, and a thermo-couple sensor measures the air temperature. The plant has thus two inputs (the fan's rotation intensity and heat generated by the resistance, both measured in percent of the maximum value) and two outputs (air temperature and air mass flux, also in percent of the maximal value). The mathematical model is obtained by System Identification techniques. The mass flux sensor, which is nonlinear, is linearized and the delays in the transfer functions are properly approximated by non-minimum phase transfer functions. The resulting model is transformed to a state-space model, which is used for control design purposes. The multivariable robust control design techniques used is the LQG/LTR, and the controllers are validated in simulation software and in the real plant. Finally, the MPC is applied by considering some of the system's parameters as random variables (one at a time, and the system's stochastic differential equations are solved by expanding the solution (a stochastic process) in an orthogonal basis of polynomial functions of the basic random variables. This method transforms the stochastic equations in a set of deterministic differential equations, which can be solved by traditional numerical methods (That is the MPC). Statistical data for the system (like expected values and variances) are then calculated. The effects of randomness in the parameters are evaluated in the open-loop and closed-loop pole's positions.

  15. Air pollution prevention through urban heat island mitigation: An update on the urban heat island pilot project

    SciTech Connect

    Gorsevski, V.; Taha, H.; Quattrochi, D.; Luvall, J.

    1998-07-01

    Urban heat islands increase the demand for cooling energy and accelerate the formation of smog. They are created when natural vegetation is replaced by heat-absorbing surfaces such as building roofs and walls, parking lots, and streets. Through the implementation of measures designed to mitigate the urban heat island, communities can decrease their demand for energy and effectively cool the metropolitan landscape. In addition to the economic benefits, using less energy leads to reductions in emission of CO{sub 2}--a greenhouse gas--as well as ozone (smog) precursors such as NOx and VOCs. Because ozone is created when NOx and VOCs photochemically combine with heat and solar radiation, actions taken to lower ambient air temperature can significantly reduce ozone concentrations in certain areas. Measures to reverse the urban heat island include afforestation and the widespread use of highly reflective surfaces. To demonstrate the potential benefits of implementing these measures, EPA has teamed up with NASA and LBNL to initiate a pilot project with three US cities. As part of the pilot, NASA will use remotely-sensed data to quantify surface temperature, albedo, the thermal response number and NDVI vegetation of each city. This information will be used by scientists at Lawrence Berkeley National Laboratory (LBNL) along with other data as inputs to model various scenarios that will help quantify the potential benefits of urban heat island mitigation measures in terms of reduced energy use and pollution. This paper will briefly describe this pilot project and provide an update on the progress to date.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  17. A method of exploration of the atmosphere of Titan. [hot air balloon heated by solar radiation or planetary thermal flux

    NASA Technical Reports Server (NTRS)

    Blamont, J.

    1978-01-01

    A hot-air balloon, with the air heated by natural sources, is described. Buoyancy is accomplished by either solar heating or by utilizing the IR thermal flux of the planet to heat the gas in the balloon. Altitude control is provided by a valve which is opened and closed by a barometer. The balloon is made of an organic material which has to absorb radiant energy and to emit as little as possible.

  18. Effectiveness and humidification capacity investigation of liquid-to-air membrane energy exchanger under low heat capacity ratios at winter air conditions

    NASA Astrophysics Data System (ADS)

    Kassai, Miklos

    2015-06-01

    In this research, a novel small-scale single-panel liquid-to-air membrane energy exchanger has been used to numerically investigate the effect of given number of heat transfer units (4.5), different cold inlet air temperature (1.7, 5.0, 10.0 °C) and different low heat capacity ratio (0.4, 0.5, 0.6, 0.7, 0.8, 0.9) on the steady-state performance of the energy exchanger. This small-scale energy exchanger represents the full-scale prototypes well, saving manufacturing costs and time. Lithium chloride is used as a salt solution in the system and the steady-state total effectiveness of the exchanger is evaluated for winter inlet air conditions. The results show that total effectiveness of the energy exchanger decreases with heat capacity ratio in the mentioned range. Maximum numerical total effectiveness of 97% is achieved for the energy exchanger. Increasing the heat capacity ratio values on given inlet air temperature, the humidification capacity of energy exhanger is also investigated in this paper. The humidification performance increases with heat capacity ratio. The highest humidification performance (4.53 g/kg) can be reached when inlet air temperature is 1.7 °C, and heat capacity ratio is 1.0 in winter inlet air conditions in the range of low heat capacity ratio.

  19. High-efficiency gas heat pump air-conditioner equipped with absorption refrigerator

    NASA Astrophysics Data System (ADS)

    Imai, Yosuke; Ohashi, Toshinori; Okamoto, Hiroaki; Hihara, Eiji; Kawakami, Ryuichiro

    On conventional gas heat pump(GHP), waste heat from gas engine that uses as driving source is emitted into outside. So from the standpoint of efficient use of waste heat, it is assumed that waste heat from gas engine is used as driving source of absorption chiller, and high temperature condensate refrigerant in GHP is subcooled to middle temperature by cold source from absorption cycle, and as a result, GHP makes more efficiency. However, in equipping GHP with absorption cycle, downsizing and high-efficiency of absorption cycle is required. In this study, air-cooled subcooled adiabatic absorber is focused and physical phenomenon in it is analyzed, and finally one perception of the optimized designing is shown.

  20. Energy Saving Potentials and Air Quality Benefits of Urban Heat Island Mitigation

    SciTech Connect

    Akbari, Hashem

    2005-08-23

    Urban areas tend to have higher air temperatures than their rural surroundings as a result of gradual surface modifications that include replacing the natural vegetation with buildings and roads. The term ''Urban Heat Island'' describes this phenomenon. The surfaces of buildings and pavements absorb solar radiation and become extremely hot, which in turn warm the surrounding air. Cities that have been ''paved over'' do not receive the benefit of the natural cooling effect of vegetation. As the air temperature rises, so does the demand for air-conditioning (a/c). This leads to higher emissions from power plants, as well as increased smog formation as a result of warmer temperatures. In the United States, we have found that this increase in air temperature is responsible for 5-10% of urban peak electric demand for a/c use, and as much as 20% of population-weighted smog concentrations in urban areas. Simple ways to cool the cities are the use of reflective surfaces (rooftops and pavements) and planting of urban vegetation. On a large scale, the evapotranspiration from vegetation and increased reflection of incoming solar radiation by reflective surfaces will cool a community a few degrees in the summer. As an example, computer simulations for Los Angeles, CA show that resurfacing about two-third of the pavements and rooftops with reflective surfaces and planting three trees per house can cool down LA by an average of 2-3K. This reduction in air temperature will reduce urban smog exposure in the LA basin by roughly the same amount as removing the basin entire onroad vehicle exhaust. Heat island mitigation is an effective air pollution control strategy, more than paying for itself in cooling energy cost savings. We estimate that the cooling energy savings in U.S. from cool surfaces and shade trees, when fully implemented, is about $5 billion per year (about $100 per air-conditioned house).

  1. Experimental and predicted heating distributions for biconics at incidence in air at Mach 10

    NASA Technical Reports Server (NTRS)

    Miller, C. G., III

    1984-01-01

    Heating distributions were measured on a 1.9-percent-scale model of a generic aeroassisted vehicle proposed for missions to a number of planets and for use as a moderate lift-drag ratio Earth orbital transfer vehicle. This vehicle is spherically blunted, 12.84 deg/7 deg biconic with the fore-cone bent upward 7 deg to provide self-trim capability. A straight biconic with the same nose radius and the same half-angles was also tested. The free-stream Reynolds numbers based on model length were equal to about 2 x 10(5) or 9 x 10 (5). The angle of attack, referenced to the aft-cone, was varied from 0 deg to 20 deg. Heating distributions predicted with a parabolized Navier-Stokes (PNS) code are compared with the measurements for the present Reynolds numbers and range of angles of attack. Leeward heating was greatly affected by Reynolds number, with the heating increasing with decreasing Reynolds number for attached flow (low incidence). The opposite was true for separated flow, which occurred when the fore-cone angle of attack exceeded 0.8 times the fore-cone half-angle. Windward heating distributions were predicted to within 10 percent with the PNS code. Leeward heating distributions were predicted qualitatively for both Reynolds numbers, but quantitative agreement was poorer than on the windward side.

  2. The transference of heat from a hot plate to an air stream

    NASA Technical Reports Server (NTRS)

    Elias, Franz

    1931-01-01

    The object of the present study was to define experimentally the field of temperature and velocity in a heated flat plate when exposed to an air stream whose direction is parallel to it, then calculate therefrom the heat transference and the friction past the flat plate, and lastly, compare the test data with the mathematical theory. To ensure comparable results, we were to actually obtain or else approximate: a) two-dimensional flow; b) constant plate temperature in the direction of the stream. To approximate the flow in two dimensions, we chose a relatively wide plate and measured the velocity and temperature in the median plane.

  3. Towards energy efficient operation of Heating, Ventilation and Air Conditioning systems via advanced supervisory control design

    NASA Astrophysics Data System (ADS)

    Oswiecinska, A.; Hibbs, J.; Zajic, I.; Burnham, K. J.

    2015-11-01

    This paper presents conceptual control solution for reliable and energy efficient operation of heating, ventilation and air conditioning (HVAC) systems used in large volume building applications, e.g. warehouse facilities or exhibition centres. Advanced two-level scalable control solution, designed to extend capabilities of the existing low-level control strategies via remote internet connection, is presented. The high-level, supervisory controller is based on Model Predictive Control (MPC) architecture, which is the state-of-the-art for indoor climate control systems. The innovative approach benefits from using passive heating and cooling control strategies for reducing the HVAC system operational costs, while ensuring that required environmental conditions are met.

  4. Life Cycle Cost Analyses of U.S. Air Force Heating Plants

    DTIC Science & Technology

    1989-08-01

    1989. 31 ORNL/TM- 11146 internal Distribution 1. D. W. Burton 17. V. K. Wilkinson 2. E. C. Fox 18-20. J. M. Young 3 -7. F. P. Griffin 21. Central Research...required for the heating plant operation are assumed to follow the standard "bathtub" reliability curve as shown in Fig. 3 . The first three years of...ORNL/TM- 11146 NOAK RIDGE ~NATIONAL N LABORATORY Life-Cycle Cost Analyses of U.S.Air Force Heating Plants V. K. Wilkinson DTI * ~DI LECT A’roreve-3f

  5. Fungal colonization of air filters for use in heating, ventilating, and air conditioning (HVAC) systems.

    PubMed

    Simmons, R B; Crow, S A

    1995-01-01

    New and used cellulosic air filters for HVAC systems including those treated with antimicrobials were suspended in vessels with a range of relative humidities (55-99%) and containing non-sterile potting soil which stimulates fungal growth. Most filters yielded fungi prior to suspension in the chambers but only two of 14 nontreated filters demonstrated fungal colonization following use in HVAC systems. Filters treated with antimicrobials, particularly a phosphated amine complex, demonstrated markedly less fungal colonization than nontreated filters. In comparison with nontreated cellulosic filters, fungal colonization of antimicrobial-treated cellulosic filters was selective and delayed.

  6. The RD/D opportunities for large air-conditioning and heat-pump systems

    NASA Astrophysics Data System (ADS)

    MacDonald, M.; Goldenberg, D.; Hudgins, E.

    1982-06-01

    The marketplace factors that constrain a more rapid implementation of energy-conserving heating, ventilating, and air conditioning (HVAC) systems and system operation in commercial buildings are summarized. The focus was on large air conditioning and heat pump equipment. Use of currently available energy-efficient equipment and systems is presently limited by the economic situation of the building owners. Although case histories of energy-efficient buildings highlight the potential of new and existing equipment and systems, the majority of systems and equipment being installed today do not measure up to that potential. The major recommendations deal with developing the market for energy-efficient HVAC systems by reversing existing market forces that promote energy consumption; promoting technical research and educational programs; increasing the number of technical people competent in the area of high-efficiency system application and maintenance.

  7. Adaptive individual-cylinder thermal state control using intake air heating for a GDCI engine

    DOEpatents

    Roth, Gregory T.; Sellnau, Mark C.

    2016-08-09

    A system for a multi-cylinder compression ignition engine includes a plurality of heaters, at least one heater per cylinder, with each heater configured to heat air introduced into a cylinder. Independent control of the heaters is provided on a cylinder-by-cylinder basis. A combustion parameter is determined for combustion in each cylinder of the engine, and control of the heater for that cylinder is based on the value of the combustion parameter for combustion in that cylinder. A method for influencing combustion in a multi-cylinder compression ignition engine, including determining a combustion parameter for combustion taking place in a cylinder of the engine and controlling a heater configured to heat air introduced into that cylinder, is also provided.

  8. Oblique view of east side mechanical additions and south side ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Oblique view of east side mechanical additions and south side of 1955 addition, facing northwest. - Albrook Air Force Station, Dispensary, East side of Canfield Avenue, Balboa, Former Panama Canal Zone, CZ

  9. Application information on typical hygrometers used in heating, ventilating and air conditioning (HVAC) systems

    SciTech Connect

    Kao, J.Y.; Snyder, W.J.

    1982-01-01

    Hygrometer selection information is provided for application in heating, ventilating and air-conditioning (HVAC) systems. A general review of hygrometer literature has been provided and the most commonly used ones for HVAC are discussed. Typical hygrometer parameters are listed to indicate the type of performance that can be expected. Laboratory test results of self-regulating, salt-phase transition hygrometers are presented and discussed in detail.

  10. Heat transfer characteristics of a single circular air jet impinging on a concave hemispherical shell

    NASA Technical Reports Server (NTRS)

    Livingood, J. N. B.; Gauntner, J. W.

    1973-01-01

    An experimental study was made of the local and average heat-transfer characteristics of a single turbulent air jet impinging on the concave surface of a hemisphere. Correlations were developed for expressing the effects of a number of dimensionless variables on the local and average Nusselt numbers. Results of the present study are compared with those from a similar study concerning a concave surface of a semicylindrical shell.

  11. Air jet levitation furnace system for observing glass microspheres during heating and melting

    NASA Technical Reports Server (NTRS)

    Ethridge, E. C.; Dunn, S. L.

    1982-01-01

    A collimated hole structure air jet levitation system has been developed which can be used to levitate hollow glass microspheres used in inertial confinement fusion studies. An ellipsoidal furnace has been added to the system to provide a heating source. A video camera and a 16 mm movie camera connected to a microsphere system provide real time observation as well as permanent documentation of the experiments. Microspheres have been levitated at temperatures over 1400 C for over 10 minutes at a time.

  12. Computer Simulation of Solar Air Heating Systems Using Rock Bed Thermal Storage Units.

    DTIC Science & Technology

    1980-12-01

    contributes rather insignificantly when determining the life cycle cost effectiveness of the air heating system. Also, with the above conditions but for 24...freeze or boil and materials used in the system generally have a long life expectancy. aintenance of the system is expected to be low if quality...average long term clearness index. XT is the ratio of Fi to Ho, is the extraterrestial radiation on a horizontal surface. To find the incident beam

  13. Demand Controlled Economizer Cycles: A Direct Digital Control Scheme for Heating, Ventilating, and Air Conditioning Systems,

    DTIC Science & Technology

    1984-05-01

    includes a heating coil and thermostatic control to maintain the air in this path at an elevated temperature, typically around 80 degrees Farenheit (80 F...1238 Aug 1 1236 1237 52 1074 1126 50 1033 1083 Sep 8 8 5W 862 7T 600 678 75 603 7r Oct 51 400 451 119 204 323 115 207 322 ov 64 123 287 187 71 258

  14. Central Heat and Power Plant Coal Dust and Silica Risk Management, Eielson Air Force Base, Alaska

    DTIC Science & Technology

    2014-12-11

    evaluation of potential ammonia exposures at the Eielson Air Force Base (EAFB) Central Heat and Power Plant (CHPP) following the installation of a new...boiler and emission controls. While the main purpose of the visit was an ammonia health risk assessment, the potential exposure to coal dust and...addition to the main ammonia health risk assessment letter and designed to inform EAFB of the status of the pending silica rule, exposure assessment

  15. Air-Source Integrated Heat Pump for Near-Zero Energy Houses: Technology Status Report

    SciTech Connect

    Murphy, Richard W; Rice, C Keith; Baxter, Van D; Craddick, William G

    2007-07-01

    This report documents the development of an air-source integrated heat pump (AS-IHP) through the third quarter of FY2007. It describes the design, analyses and testing of the AS-IHP, and provides performance specifications for a field test prototype and proposed control strategy. The results obtained so far continue to support the AS-IHP being a promising candidate to meet the energy service needs for DOE's development of a Zero Energy Home (ZEH) by the year 2020.

  16. A custom flexible experimental setup to test air source heat pump for smart buildings

    NASA Astrophysics Data System (ADS)

    Cracium, Vasile S.; Bojesen, Carsten; Trifa, Viorel

    2012-09-01

    In this paper a custom made experimental stand is presented, named controlled lab environment (CLE or climatic box), built for testing an air source heat pump (ASHP) under controlled evaporator ambient conditions and verify the performance and behavior of a theoretical model of the ASHP as a basis for optimization and efficiency improvements. While the data acquisitions from experiments are not yet available, the paper presents the design considerations and schematics of the CLE and a thermodynamic model of an ASHP.

  17. Zoning of the territory of Russia by the effectiveness of low-potential heat of the ground and atmospheric air for heating buildings

    NASA Astrophysics Data System (ADS)

    Vasilyev, G. P.; Kolesova, M. V.; Gornov, V. F.; Yurchenko, I. A.

    2016-06-01

    The article represents the results of researches to zone the territory of Russia and Europe division into districts of by efficiency of using for the heat supply of buildings of low-potential thermal energy of ground and free air and their combination. While modeling the heat regime of geothermal HPS in climatic conditions of different regions of the territory of Russia, the influence of the long-term extraction of geothermal heat energy on the ground heat regime has been taken into account as well as the influence of phase transitions of pore moisture in ground on the efficiency of operation of geothermal heat-pump heat-supply systems. Also considered were the sinking of temperatures of ground massif by long-term extraction of the heat energy from the ground as calculation parameters of the heat energy from the ground, and as calculation parameters of ground massif temperatures.

  18. The Maintenance of Heating, Ventilating and Air-Conditioning Systems and Indoor Air Quality in Schools: A Guide for School Facility Managers. Technical Bulletin.

    ERIC Educational Resources Information Center

    Wheeler, Arthur E.

    To help maintain good indoor air quality (IAQ) in schools, guidance for the development and implementation of an effective program for maintenance and operation of heating, ventilating, and air-conditioning (HVAC) systems are discussed. Frequently, a building's occupants will complain about IAQ when the temperature or humidity are at uncomfortable…

  19. Heat flux: thermohydraulic investigation of solar air heaters used in agro-industrial applications

    NASA Astrophysics Data System (ADS)

    Rahmati Aidinlou, H.; Nikbakht, A. M.

    2017-03-01

    A new design of solar air heater simulator is presented to comply with the extensive applications inagro-industry. A wise installation of increased heat transfer surface area provided uniform and efficient heat diffusion over the duct. Nusselt number and friction factor have been investigated based on the constant roughness parameters such as relative roughness height (e/D), relative roughness pitch (P/e), angle of attack (α) and aspect ratio with Reynolds numbers ranging from 5000 to 19,000 in the fully developed region. Heat fluxes of 800, 900 and 1000 Wm-2 were provided. The enhancement in friction factor is observed to be 3.1656, 3.47 and 3.0856 times, and for the Nusselt number either, augmentation is calculated to be 1.4437, 1.4963 and 1.535 times, respectively, over the smooth duct for 800, 900 and 1000 Wm-2 heat fluxes. Thermohydraulic performance is plotted versus the Reynolds number based on the aforementioned roughness parameters at varying heat fluxes. The results show up that thermohydraulic performance is found to be maximum for 1000 Wm-2 at the average Reynolds number of 5151. Based on the results, we can verify that the introduced solar simulator can help analyzing and developing solar collector installations at the simulated heat fluxes.

  20. Gas Engine-Driven Heat Pump Chiller for Air-Conditioning and Hot Water Supply Systems

    NASA Astrophysics Data System (ADS)

    Fujita, Toshihiko; Mita, Nobuhiro; Moriyama, Tadashi; Hoshino, Norimasa; Kimura, Yoshihisa

    A gas engine-driven heat pump (GHP) uses a natural gas-or LPG-powered engine to drive the compressor in a vapor-compression refrigeration cycle. The GHP has the benefits of being able to use the fuel energy effectively by recovering waste heat from the engine jacket coolant and exhaust gas and also to keep high efficiency even at part-load operation by varying the engine speed with relative ease. Hence, energy-efficient heat source systems for air-conditioning and hot water supply may be constructed with GHP chillers in place of conventional electrical-driven heat pump chillers. GHPs will necessarily contribute to the peak shaving of electrical demand in summer. In this study, the performance characteristics of a 457kW GHP chiller have been investigated by a simulation model analysis, for both cooling and heating modes. From the results of the analysis, it has been found that the part-load characteristics of the GHP chiller are fairly well. The evaluation of the heat source systems using GHP chillers will be described in Part 2.

  1. Cotton gin trash incinerator-air heat project. Consultant report (final)

    SciTech Connect

    Not Available

    1980-05-01

    The California Energy Commission has funded the final phase of a four year project resulting in development of a successful system for burning cotton gin trash as a fuel providing the heat for ginning. The incinerator - air heater system installed in Corcoran, California operates continuously throughout the ginning season. Trash feeding and burning rate is automatically controlled from the combustion temperature, hot air temperature is controlled by the drying needs, and ashes are automatically removed from the system and pneumatically conveyed to the disposal site. The system complies with state and county air pollution codes by means of baghouse collectors. Savings in fossil fuel and trash disposal costs have demonstrated the equipment system is feasible for a four year payback at large, well utilized gins.

  2. Vortex shedding induced energy harvesting from piezoelectric materials in heating, ventilation and air conditioning flows

    NASA Astrophysics Data System (ADS)

    Weinstein, L. A.; Cacan, M. R.; So, P. M.; Wright, P. K.

    2012-04-01

    A cantilevered piezoelectric beam is excited in a heating, ventilation and air conditioning (HVAC) flow. This excitation is amplified by the interactions between (a) an aerodynamic fin attached at the end of the piezoelectric cantilever and (b) the vortex shedding downstream from a bluff body placed in the air flow ahead of the fin/cantilever assembly. The positioning of small weights along the fin enables tuning of the energy harvester to operate at resonance for flow velocities from 2 to 5 m s-1, which are characteristic of HVAC ducts. In a 15 cm diameter air duct, power generation of 200 μW for a flow speed of 2.5 m s-1 and power generation of 3 mW for a flow speed of 5 m s-1 was achieved. These power outputs are sufficient to power a wireless sensor node for HVAC monitoring systems or other sensors for smart building technology.

  3. Experimental study of convective heat transfer of compressed air flow in radially rotating ducts

    SciTech Connect

    Hwang, G.J,; Tzeng, S.C.; Mao, C.P.

    1999-07-01

    The convective heat transfer of pressurized air flow in radially rotating serpentine channel is investigated experimentally in the present study. The main governing parameters are the Prandtl number, the Reynolds number for forced convection, the rotation number for the Coriolis force induced cross stream secondary flow and the Grashof number for natural convection. To simulate the operation conditions of a real gas turbine, the present study kept the parameters in the test rig approximately the same as those in a real engine. The air in the present serpentine channel was pressurized to increase the air density for making up the low rotational speed in the experiment. Before entering the rotating ducts, the air was also cooled to gain a high density ratio of approximately 1/3 in the ducts. This high density ratio will give a similar order of magnitude of Grashof number in a real operation condition. The local heat transfer rate on the four channel walls are present and compared with that in existing literature.

  4. Seasonal and Diurnal Air Pollution from Residential Cooking and Space Heating in the Eastern Tibetan Plateau.

    PubMed

    Carter, Ellison; Archer-Nicholls, Scott; Ni, Kun; Lai, Alexandra M; Niu, Hongjiang; Secrest, Matthew H; Sauer, Sara M; Schauer, James J; Ezzati, Majid; Wiedinmyer, Christine; Yang, Xudong; Baumgartner, Jill

    2016-08-02

    Residential combustion of solid fuel is a major source of air pollution. In regions where space heating and cooking occur at the same time and using the same stoves and fuels, evaluating air-pollution patterns for household-energy-use scenarios with and without heating is essential to energy intervention design and estimation of its population health impacts as well as the development of residential emission inventories and air-quality models. We measured continuous and 48 h integrated indoor PM2.5 concentrations over 221 and 203 household-days and outdoor PM2.5 concentrations on a subset of those days (in summer and winter, respectively) in 204 households in the eastern Tibetan Plateau that burned biomass in traditional stoves and open fires. Using continuous indoor PM2.5 concentrations, we estimated mean daily hours of combustion activity, which increased from 5.4 h per day (95% CI: 5.0, 5.8) in summer to 8.9 h per day (95% CI: 8.1, 9.7) in winter, and effective air-exchange rates, which decreased from 18 ± 9 h(-1) in summer to 15 ± 7 h(-1) in winter. Indoor geometric-mean 48 h PM2.5 concentrations were over two times higher in winter (252 μg/m(3); 95% CI: 215, 295) than in summer (101 μg/m(3); 95%: 91, 112), whereas outdoor PM2.5 levels had little seasonal variability.

  5. Effect of excess air on the optimization of heating appliances for biomass combustion

    SciTech Connect

    Menghini, D.; Marra, F.S.; Allouis, C.; Beretta, F.

    2008-07-15

    The performance of a domestic appliance for wood logs combustion is a function of several variables, such as the geometric design of the appliance and its operating parameters. Among them, air feeding conditions are really decisive if the objective function is the maximization of the heat recovered from flue gases. Therefore, even if pollutant emissions have to be ever considered, the amount of excess air can be seen as a fundamental parameter in the definition of thermal efficiency of the appliance. In this paper the role of this parameter is analysed. The analysis is conducted by linking the results obtained from experimental data, detailed CFD simulations and a simplified mathematical model based on a network of CSTR. The derivation of an idealized schematization of the appliance was essential to realize the role of excess air variations, with more generality than with respect to a specific appliance configuration. Conversely, while the experimental data and CFD results were necessary to derive the simplified model, the indications given by this simplified model were useful to analyze results coming from both experiments and detailed numerical simulations. It has been evidenced the need to distinguish between the role of excess air in the chemical combustion and in the heat recovery in the appliance as well as to quantify the feedback between these two processes. (author)

  6. A novel method to determine air leakage in heat pump clothes dryers

    SciTech Connect

    Bansal, Pradeep; Mohabir, Amar; Miller, William

    2016-01-06

    A heat pump clothes dryer offers the potential to save a significant amount of energy as compared with conventional vented electric dryers. Although heat pump clothes dryers (HPCD) offer higher energy efficiency; it has been observed that they are prone to air leakages, which inhibits the HPCD's gain in efficiency. This study serves to develop a novel method of quantifying leakage, and to determine specific leakage locations in the dryer drum and air circulation system. The basis of this method is the American Society of Testing and Materials (ASTM) standard E779 10, which is used to determine air leakage area in a household ventilation system through fan pressurization. This ASTM method is adapted to the dryer system, and the leakage area is determined by an analysis of the leakage volumetric flow - pressure relationship. Easily accessible leakage points were quantified: the front and back crease (in the dryer drum), the leakage in the dryer duct, the air filter, and the remaining leakage in the drum. The procedure allows investigators to determine major components contributing to leakage in HPCDs, thus improving component design features that result in more efficient HPCD systems.

  7. A novel method to determine air leakage in heat pump clothes dryers

    DOE PAGES

    Bansal, Pradeep; Mohabir, Amar; Miller, William

    2016-01-06

    A heat pump clothes dryer offers the potential to save a significant amount of energy as compared with conventional vented electric dryers. Although heat pump clothes dryers (HPCD) offer higher energy efficiency; it has been observed that they are prone to air leakages, which inhibits the HPCD's gain in efficiency. This study serves to develop a novel method of quantifying leakage, and to determine specific leakage locations in the dryer drum and air circulation system. The basis of this method is the American Society of Testing and Materials (ASTM) standard E779 10, which is used to determine air leakage areamore » in a household ventilation system through fan pressurization. This ASTM method is adapted to the dryer system, and the leakage area is determined by an analysis of the leakage volumetric flow - pressure relationship. Easily accessible leakage points were quantified: the front and back crease (in the dryer drum), the leakage in the dryer duct, the air filter, and the remaining leakage in the drum. The procedure allows investigators to determine major components contributing to leakage in HPCDs, thus improving component design features that result in more efficient HPCD systems.« less

  8. Thermal control of a lidar laser system using a non-conventional ram air heat exchanger

    NASA Technical Reports Server (NTRS)

    Killough, Brian D.; Alexander, William, Jr.; Swofford, Doyle P.

    1990-01-01

    This paper describes the analysis and performance testing of a uniquely designed external heat exchanger. The heat exchanger is attached externally to an aircraft and is used to cool a laser system within the fuselage. Estimates showed insufficient cooling capacity with a conventional staggered tube array in the limited space available. Thus, a non-conventional design wes developed with larger tube and fin area exposed to the ram air to increase the heat transfer performance. The basic design consists of 28 circular finned aluminum tubes arranged in two parallel banks. Wind tunnel tests were performed to simulate air and liquid flight conditions for the non-conventional parallel bank arrangement and the conventional staggered tube arrangement. Performance comparisons of each of the two designs are presented. Test results are used in a computer model of the heat exchanger to predict the operating performance for the entire flight profile. These analyses predict significantly improved performance over the conventional design and show adequate thermal control margins.

  9. High-speed measurement of an air transect's temperature shift heated by laser beam

    NASA Astrophysics Data System (ADS)

    Li, WenYu; Jiang, ZongFu; Xi, Fengjie; Li, Qiang; Xie, Wenke

    2005-02-01

    Laser beam heat the air on the optic path, Beam-deflection optical tomography is a non-intrusive method to measure the 2-dimension temperature distribution in the transect. By means of linear Hartmann Sensor at the rate of 27kHz, the optic path was heated by a 2.7μm HF laser, continuous and high time resolution gradients of optic phase were obtained. the result of analysing and calculation showed the temperament shift in the heated beam path was not higher than 50K when the HF laser power was 9W. The experiment showed that it is a practical non-intrusive temperature shift measurement method for a small area aero-optical medium.

  10. Turbulent heat and mass transfers across a thermally stratified air-water interface

    NASA Technical Reports Server (NTRS)

    Papadimitrakis, Y. A.; Hsu, Y.-H. L.; Wu, J.

    1986-01-01

    Rates of heat and mass transfer across an air-water interface were measured in a wind-wave research facility, under various wind and thermal stability conditions (unless otherwise noted, mass refers to water vapor). Heat fluxes were obtained from both the eddy correlation and the profile method, under unstable, neutral, and stable conditions. Mass fluxes were obtained only under unstable stratification from the profile and global method. Under unstable conditions the turbulent Prandtl and Schmidt numbers remain fairly constant and equal to 0.74, whereas the rate of mass transfer varies linearly with bulk Richardson number. Under stable conditions the turbulent Prandtl number rises steadily to a value of 1.4 for a bulk Richardson number of about 0.016. Results of heat and mass transfer, expressed in the form of bulk aerodynamic coefficients with friction velocity as a parameter, are also compared with field data.

  11. Air-Cooled Heat Exchanger for High-Temperature Power Electronics: Preprint

    SciTech Connect

    Waye, S. K.; Lustbader, J.; Musselman, M.; King, C.

    2015-05-06

    This work demonstrates a direct air-cooled heat exchanger strategy for high-temperature power electronic devices with an application specific to automotive traction drive inverters. We present experimental heat dissipation and system pressure curves versus flow rate for baseline and optimized sub-module assemblies containing two ceramic resistance heaters that provide device heat fluxes. The maximum allowable junction temperature was set to 175 deg.C. Results were extrapolated to the inverter scale and combined with balance-of-inverter components to estimate inverter power density and specific power. The results exceeded the goal of 12 kW/L and 12 kW/kg for power density and specific power, respectively.

  12. An assessment of air-sea heat fluxes from ocean and coupled reanalyses

    NASA Astrophysics Data System (ADS)

    Valdivieso, Maria; Haines, Keith; Balmaseda, Magdalena; Chang, You-Soon; Drevillon, Marie; Ferry, Nicolas; Fujii, Yosuke; Köhl, Armin; Storto, Andrea; Toyoda, Takahiro; Wang, Xiaochun; Waters, Jennifer; Xue, Yan; Yin, Yonghong; Barnier, Bernard; Hernandez, Fabrice; Kumar, Arun; Lee, Tong; Masina, Simona; Andrew Peterson, K.

    2015-10-01

    Sixteen monthly air-sea heat flux products from global ocean/coupled reanalyses are compared over 1993-2009 as part of the Ocean Reanalysis Intercomparison Project (ORA-IP). Objectives include assessing the global heat closure, the consistency of temporal variability, comparison with other flux products, and documenting errors against in situ flux measurements at a number of OceanSITES moorings. The ensemble of 16 ORA-IP flux estimates has a global positive bias over 1993-2009 of 4.2 ± 1.1 W m-2. Residual heat gain (i.e., surface flux + assimilation increments) is reduced to a small positive imbalance (typically, +1-2 W m-2). This compensation between surface fluxes and assimilation increments is concentrated in the upper 100 m. Implied steady meridional heat transports also improve by including assimilation sources, except near the equator. The ensemble spread in surface heat fluxes is dominated by turbulent fluxes (>40 W m-2 over the western boundary currents). The mean seasonal cycle is highly consistent, with variability between products mostly <10 W m-2. The interannual variability has consistent signal-to-noise ratio (~2) throughout the equatorial Pacific, reflecting ENSO variability. Comparisons at tropical buoy sites (10°S-15°N) over 2007-2009 showed too little ocean heat gain (i.e., flux into the ocean) in ORA-IP (up to 1/3 smaller than buoy measurements) primarily due to latent heat flux errors in ORA-IP. Comparisons with the Stratus buoy (20°S, 85°W) over a longer period, 2001-2009, also show the ORA-IP ensemble has 16 W m-2 smaller net heat gain, nearly all of which is due to too much latent cooling caused by differences in surface winds imposed in ORA-IP.

  13. Analyzing the possibility of constructing the air heating system for an integrated solid fuel gasification combined-cycle power plant

    NASA Astrophysics Data System (ADS)

    Mikula, V. A.; Ryzhkov, A. F.; Val'tsev, N. V.

    2015-11-01

    Combined-cycle power plants operating on solid fuel have presently been implemented only in demonstration projects. One of possible ways for improving such plants consists in making a shift to hybrid process circuits of integrated gasification combined-cycle plants with external firing of solid fuel. A high-temperature air heater serving to heat compressed air is a key element of the hybrid process circuit. The article describes application of a high-temperature recuperative metal air heater in the process circuit of an integrated gasification combined-cycle power plant (IGCC). The available experience with high-temperature air heating is considered, and possible air heater layout arrangements are analyzed along with domestically produced heat-resistant grades of steel suitable for manufacturing such air heater. An alternative (with respect to the traditional one) design is proposed, according to which solid fuel is fired in a noncooled furnace extension, followed by mixing the combustion products with recirculation gases, after which the mixture is fed to a convective air heater. The use of this design makes it possible to achieve considerably smaller capital outlays and operating costs. The data obtained from thermal and aerodynamic calculations of the high-temperature air heater with a thermal capacity of 258 MW for heating air to a temperature of up to 800°C for being used in the hybrid process circuit of a combined-cycle power plant are presented.

  14. Summarized Data of Test Space Heating, Ventilation and Air Conditioning Inspections from the Building Assessment Survey and Evaluation Study

    EPA Pesticide Factsheets

    Information on the characteristics of the heating, ventilation, and air conditioning (HVAC) system(s) in the entire BASE building including types of ventilation, equipment configurations, and operation and maintenance issues

  15. Urban Heat Island Versus Air Quality - a Numerical Modelling Study for a European City

    NASA Astrophysics Data System (ADS)

    Fallmann, J.; Forkel, R.; Emeis, S.

    2014-12-01

    In 2050 70% of the global population is expected to live in urban areas. Climate change will render these areas more vulnerable to heat waves, which often are accompanied by severe air pollution problems. The Urban Heat Island (UHI) is a feature that adds to the general temperature increase that is expected. Decreasing the UHI can impact air quality as well, because heat influences atmospheric dynamics and accelerates air chemical processes and often also increases the emission of primary pollutants due to increased demand of energy. The goal of this study is to investigate the effect of, e.g., high reflective surfaces and urban greening on mitigating the UHI and the related impact on air quality. A multi-layer urban canopy model is coupled to the mesoscale model WRF-Chem and the urban area of Stuttgart (South-West Germany) is taken as one example. Different scenario runs are executed for short time periods and are compared to a control run. The results show that the UHI effect can be substantially reduced when changing the albedo of roof surfaces, whereas the effect of urban greening is minor. Both scenarios have in common, that they evoke changes in secondary circulation patterns. The effects of these mitigation strategies on chemical composition of the urban atmosphere are complex, attributed to both chemical and dynamical features. Increasing the reflectivity of roof surfaces in the model results in a net decrease of the surface ozone concentration, because ozone formation is highly correlated to temperature. With regard to primary pollutants, e.g. NO, CO and PM10 concentrations are increased when increasing reflectivity. This effect primarily can be ascribed to a reduction of turbulent motion, convection and a decrease of the boundary layer height, coming along with lower temperatures in the urban canopy layer due to increased reflectivity. The table below shows the effect on grid cell mean concentrations for different chemical species and scenarios.

  16. Affect of Air Leakage into a Thermal-Vacuum Chamber on Helium Refrigeration Heat Load

    NASA Technical Reports Server (NTRS)

    Garcia, Sam; Meagher, Daniel; Linza, Robert; Saheli, Fariborz; Vargas, Gerardo; Lauterbach, John; Reis, Carl; Ganni, Venkatarao (Rao); Homan, Jonathan

    2008-01-01

    NASA s Johnson Space Center (JSC) Building 32 houses two large thermal-vacuum chambers (Chamber A and Chamber B). Within these chambers are liquid nitrogen shrouds to provide a thermal environment and helium panels which operate at 20K to provide cryopumping. Some amount of air leakage into the chambers during tests is inevitable. This causes "air fouling" of the helium panel surfaces due to the components of the air that adhere to the panels. The air fouling causes the emittance of the helium panels to increase during tests. The increase in helium panel emittance increases the heat load on the helium refrigerator that supplies the 20K helium for those panels. Planning for thermal-vacuum tests should account for this increase to make sure that the helium refrigerator capacity will not be exceeded over the duration of a test. During a recent test conducted in Chamber B a known-size air leak was introduced to the chamber. Emittance change of the helium panels and the affect on the helium refrigerator was characterized. A description of the test and the results will be presented.

  17. Reduction in air emissions attainable through implementation of district heating and cooling

    SciTech Connect

    Bloomquist, R.G.

    1996-12-31

    District heating and cooling (DHC) can provide multiple opportunities to reduce air emissions associated with space conditioning and electricity generation, which contribute 30% to 50% of all such emissions. When DHC is combined with cogeneration (CHP), maximum reductions in sulfur oxides (SO{sub x}), nitrogen oxides (NO{sub x}), carbon dioxide (CO{sub 2}), particulates, and ozone-depleting chlorofluorocarbon (CFC) refrigerants can most effectively be achieved. Although significant improvements in air quality have been documented in Europe and Scandinavia due to DHC and CHP implementation, accurately predicting such improvements has been difficult. Without acceptable quantification methods, regulatory bodies are reluctant to grant air emissions credits, and local community leaders are unwilling to invest in DHC and CHP as preferred methods of providing energy or strategies for air quality improvement. The recent development and release of a number of computer models designed specifically to provide quantification of air emissions that can result from DHC and CHP implementation should help provide local, state, and national policymakers with information vital to increasing support and investment in DHC development.

  18. Potential Evaluation of Solar Heat Assisted Desiccant Hybrid Air Conditioning System

    NASA Astrophysics Data System (ADS)

    Tran, Thien Nha; Hamamoto, Yoshinori; Akisawa, Atsushi; Kashiwagi, Takao

    The solar thermal driven desiccant dehumidification-absorption cooling hybrid system has superior advantage in hot-humid climate regions. The reasonable air processing of desiccant hybrid air conditioning system and the utility of clean and free energy make the system environment friendly and energy efficient. The study investigates the performance of the desiccant dehumidification air conditioning systems with solar thermal assistant. The investigation is performed for three cases which are combinations of solar thermal and absorption cooling systems with different heat supply temperature levels. Two solar thermal systems are used in the study: the flat plate collector (FPC) and the vacuum tube with compound parabolic concentrator (CPC). The single-effect and high energy efficient double-, triple-effect LiBr-water absorption cooling cycles are considered for cooling systems. COP of desiccant hybrid air conditioning systems are determined. The evaluation of these systems is subsequently performed. The single effect absorption cooling cycle combined with the flat plate collector solar system is found to be the most energy efficient air conditioning system.

  19. A novel trapezoid fin pattern applicable for air-cooled heat sink

    NASA Astrophysics Data System (ADS)

    Chen, Chien-Hung; Wang, Chi-Chuan

    2015-11-01

    The present study proposed a novel step or trapezoid surface design applicable to air-cooled heat sink under cross flow condition. A total of five heat sinks were made and tested, and the corresponding fin patterns are (a) plate fin; (b) step fin (step 1/3, 3 steps); (c) 2-step fin (step 1/2, 2 steps); (d) trapezoid fin (trap 1/3, cutting 1/3 length from the rear end) and (e) trapezoid fin (trap 1/2, cutting 1/2 length from the rear end). The design is based on the heat transfer augmentation via (1) longer perimeter of entrance region and (2) larger effective temperature difference at the rear part of the heat sink. From the test results, it is found that either step or trapezoid design can provide a higher heat transfer conductance and a lower pressure drop at a specified frontal velocity. The effective conductance of trap 1/3 design exceeds that of plate surface by approximately 38 % at a frontal velocity of 5 m s-1 while retains a lower pressure drop of 20 % with its surface area being reduced by 20.6 %. For comparisons exploiting the overall thermal resistance versus pumping power, the resultant thermal resistance of the proposed trapezoid design 1/3, still reveals a 10 % lower thermal resistance than the plate fin surface at a specified pumping power.

  20. Heat treatment's effects on hydroxyapatite powders in water vapor and air atmosphere

    NASA Astrophysics Data System (ADS)

    Karabulut, A.; Baştan, F. E.; Erdoǧan, G.; Üstel, F.

    2015-03-01

    Hydroxyapatite (HA; Ca10(PO4)6(OH)2) is the main chemical constituent of bone tissue (~70%) as well as HA which is a calcium phosphate based ceramic material forms inorganic tissue of bone and tooth as hard tissues is used in production of prosthesis for synthetic bone, fractured and broken bone restoration, coating of metallic biomaterials and dental applications because of its bio compatibility. It is known that Hydroxyapatite decomposes with high heat energy after heat treatment. Therefore hydroxyapatite powders that heated in water vapor will less decomposed phases and lower amorphous phase content than in air atmosphere. In this study high purity hydroxyapatite powders were heat treated with open atmosphere furnace and water vapor atmosphere with 900, 1000, 1200 °C. Morphology of same powder size used in this process by SEM analyzed. Chemical structures of synthesized coatings have been examined by XRD. The determination of particle size and morphological structure of has been characterized by Particle Sizer, and SEM analysis, respectively. Weight change of sample was recorded by thermogravimetric analysis (TGA) during heating and cooling.

  1. Mechanisms controlling the SST air-sea heat flux feedback and its dependence on spatial scale

    NASA Astrophysics Data System (ADS)

    Hausmann, Ute; Czaja, Arnaud; Marshall, John

    2017-02-01

    The turbulent air-sea heat flux feedback (α, in {W m}^{-2} { K}^{-1}) is a major contributor to setting the damping timescale of sea surface temperature (SST) anomalies. In this study we compare the spatial distribution and magnitude of α in the North Atlantic and the Southern Ocean, as estimated from the ERA-Interim reanalysis dataset. The comparison is rationalized in terms of an upper bound on the heat flux feedback, associated with "fast" atmospheric export of temperature and moisture anomalies away from the marine boundary layer, and a lower bound associated with "slow" export. It is found that regions of cold surface waters (≤10 ° C) are best described as approaching the slow export limit. This conclusion is not only valid at the synoptic scale resolved by the reanalysis data, but also on basin scales. In particular, it applies to the heat flux feedback acting as circumpolar SST anomaly scales are approached in the Southern Ocean, with feedbacks of ≤10 {W m}^{-2} { K}^{-1}. In contrast, the magnitude of the heat flux feedback is close to that expected from the fast export limit over the Gulf Stream and its recirculation with values on the order of ≈40 {W m}^{-2} { K}^{-1}. Further analysis suggests that this high value reflects a compensation between a moderate thermodynamic adjustment of the boundary layer, which tends to weaken the heat flux feedback, and an enhancement of the surface winds over warm SST anomalies, which tend to enhance the feedback.

  2. Turbine heat transfer

    NASA Technical Reports Server (NTRS)

    Rohde, J. E.

    1982-01-01

    Objectives and approaches to research in turbine heat transfer are discussed. Generally, improvements in the method of determining the hot gas flow through the turbine passage is one area of concern, as is the cooling air flow inside the airfoil, and the methods of predicting the heat transfer rates on the hot gas side and on the coolant side of the airfoil. More specific areas of research are: (1) local hot gas recovery temperatures along the airfoil surfaces; (2) local airfoil wall temperature; (3) local hot gas side heat transfer coefficients on the airfoil surfaces; (4) local coolant side heat transfer coefficients inside the airfoils; (5) local hot gas flow velocities and secondary flows at real engine conditions; and (6) local delta strain range of the airfoil walls.

  3. Heat transfer and pressure distributions on hemisphere-cylinders in methane-air combustion products at Mach 7

    NASA Technical Reports Server (NTRS)

    Weinstein, I.

    1973-01-01

    Heat-transfer and pressure distributions were measured over the surfaces of three hemisphere-cylinder models tested at a nominal Mach number of 7 in the Langley 8-foot high-temperature structures tunnel which uses methane-air products of combustion as a test medium. The results showed that the heat-transfer and pressure distributions over the surface of the models were in good agreement with experimental data obtained in air and also with theoretical predictions.

  4. High heat flux single phase heat exchanger

    NASA Technical Reports Server (NTRS)

    Valenzuela, Javier A.; Izenson, Michael G.

    1990-01-01

    This paper presents the results obtained to date in a program to develop a high heat flux, single-phase heat exchanger for spacecraft thermal management. The intended application is a net generation interface heat exchanger to couple the crew module water thermal bus to the two-phase ammonia main thermal bus in the Space Station Freedom. The large size of the interface heat exchanger is dictated by the relatively poor water-side heat transfer characteristics. The objective of this program is to develop a single-phase heat transfer approach which can achieve heat fluxes and heat transfer coefficients comparable to those of the evaporation ammonia side. A new heat exchanger concept has been developed to meet these objecties. The main feature of this heat exchanger is that it can achieve very high heat fluxes with a pressure drop one to two orders of magnitude lower than those of previous microchannel or jet impingement high heat flux heat exchangers. This paper describes proof-of-concept experiments performed in air and water and presents analytical model of the heat exchanger.

  5. Effects of a Circulating-water Garment and Forced-air Warming on Body Heat Content and Core Temperature

    PubMed Central

    Taguchi, Akiko; Ratnaraj, Jebadurai; Kabon, Barbara; Sharma, Neeru; Lenhardt, Rainer; Sessler, Daniel I.

    2005-01-01

    Background: Forced-air warming is sometimes unable to maintain perioperative normothermia. We therefore compared heat transfer, regional heat distribution, and core rewarming of forced-air warming with a novel circulating-water garment. Methods: Nine volunteers were each evaluated on two randomly ordered study days. They were anesthetized and cooled to a core temperature near 34°C. The volunteers were subsequently warmed for 2.5 hours with either a circulating-water garment or forced-air cover. Overall, heat balance was determined from the difference between cutaneous heat loss (thermal flux transducers) and metabolic heat production (oxygen consumption). Average arm and leg (peripheral) tissue temperatures were determined from 18 intramuscular needle thermocouples, 15 skin thermal flux transducers, and “deep” arm and foot thermometers. Results: Heat production (≈ 60 kcal/h) and loss (≈45 kcal/h) were similar with each treatment before warming. The increase in heat transfer across anterior portions of the skin surface was similar with each warming system (≈65 kcal/h). Forced-air warming had no effect on posterior heat transfer whereas circulating-water transferred 21 ± 9 kcal/h through the posterior skin surface after a half hour of warming. Over 2.5 h, circulating-water thus increased body heat content 56% more than forced air. Core temperatures thus increased faster than with circulating water than forced air, especially during the first hour, with the result that core temperature was 1.1 ± 0.7°C greater after 2.5 h (P < 0.001). Peripheral tissue heat content increased twice as much as core heat content with each device, but the core-to-peripheral tissue temperature gradient remained positive throughout the study. Conclusions: The circulating-water system transferred more heat than forced air, with the difference resulting largely from posterior heating. Circulating water rewarmed patients 0.4°C/h faster than forced air. A substantial peripheral

  6. Investigation of Effectiveness of Air-Heating a Hollow Steel Propeller for Protection Against Icing. 2: 50% Impartitioned Blades

    NASA Technical Reports Server (NTRS)

    Perkins, Porter J.; Mulholland, Donald R.

    1948-01-01

    The icing protection afforded an internal air-heated propeller blade by radial partitioning at 50-percent chord to confine the heated air to the forward half of the blade was determined in the NACA Cleveland icing research tunnel. A modified production-model hollow steel propeller, was used for the investigation. Temperatures of the blade surfaces for several heating rates were measured under various tunnel Icing' conditions. Photographic observations of ice formations on blade surfaces and blade heat-exchanger effectiveness were obtained. With 50-percent partitioning of the blades, adequate icing protection at 1050 rpm was obtained with a heating rate of 26,000 Btu per hour per blade at the blade shank using an air temperature of 400 F with a flow rate of 280 pounds per hour per blade, which is one-third less heat than was found necessary for similar Ice protection with unpartitioned blades. The chordwise distribution of the applied heat, as determined by surface temperature measurements, was considered unsatisfactory with much of the heat dissipated well back of the leading edge. Heat-exchanger effectiveness of approximately 56 percent also Indicated poor utilization of available heat. This effectiveness was, however, 9 percent greater than that obtained from unpartitioned blades.

  7. AN ASSESSMENT OF THE STATE OF THE ART, AND POTENTIAL DESIGN IMPROVEMENTS, FOR FLAT-TUBE HEAT EXCHANGERS IN AIR CONDITIONING AND REFRIGERATION APPLICATIONS - PHASE I

    SciTech Connect

    Jacobi, A.M.; Park, Y.; Tafti, D.; Zhang, X.

    2001-09-30

    Project objective is to evaluate the air-side heat transfer and pressure-drop performance of serpentine-fin, flat-tube heat exchangers. This assessment is conducted for smooth, corrugated, and interrupted fins, over a wide range of geometric and operating parameters, spanning HVAC and R applications. The performance of serpentine-fin, flat-tube exchangers is compared to that of conventional round-tube designs, which are considered the technology baseline. The research includes a literature review, a preliminary comparison of flat-tube to round-tube performance, a computational fluid dynamic study of flow through the heat exchangers, and complementary modeling to predict the performance of flat-tube designs over a wide range of conditions. Recommendations are provided for a new experimental study to provide performance data for dry, wet, and frosted-surface conditions. Specific flow visualization and naphthalene sublimation experiments are recommended to understand the flow and heat transfer interactions in the flat-tube geometry. These data could be used to evaluate condensate retention and frost-formation effects on flat-tube heat exchanger performance, and to compare this behavior to that of the conventional round-tube geometry. These findings will be highly valuable to design and development engineers as they work toward the next generation of highly compact, energy efficient HVAC and R systems.

  8. Cool Roofs in Guangzhou, China: Outdoor Air Temperature Reductions during Heat Waves and Typical Summer Conditions.

    PubMed

    Cao, Meichun; Rosado, Pablo; Lin, Zhaohui; Levinson, Ronnen; Millstein, Dev

    2015-12-15

    In this paper, we simulate temperature reductions during heat-wave events and during typical summer conditions from the installation of highly reflective "cool" roofs in the Chinese megacity of Guangzhou. We simulate temperature reductions during six of the strongest historical heat-wave events over the past decade, finding average urban midday temperature reductions of 1.2 °C. In comparison, we simulate 25 typical summer weeks between 2004 and 2008, finding average urban midday temperature reductions of 0.8 °C, indicating that air temperature sensitivity to urban albedo in Guangzhou varies with meteorological conditions. We find that roughly three-fourths of the variance in air temperature reductions across all episodes can be accounted for by a linear regression, including only three basic properties related to the meteorological conditions: mean daytime temperature, humidity, and ventilation to the greater Guangzhou urban area. While these results highlight the potential for cool roofs to mitigate peak temperatures during heat waves, the temperature reductions reported here are based on the upper bound case, which increases albedos of all roofs (but does not modify road albedo or wall albedo).

  9. Influence mechanism on flow and heat transfer characteristics for air-cooled steam condenser cells

    NASA Astrophysics Data System (ADS)

    He, Wei Feng; Dai, Yi Ping; Li, Mao Qing; Ma, Qing Zhong

    2012-09-01

    Air-cooled steam condensers (ACSCs) have been extensively utilized to reject waste heat in power industry to save water resources. However, ACSC performance is so sensitive to ambient wind that almost all the air-cooled power plants in China are less efficient compared to design conditions. It is shown from previous research that the influence of ambient wind on the cell performance differs from its location in the condenser. As a result, a numerical model including two identical ACSC cells are established, and the different influence on the performance of the cells is demonstrated and analyzed through the computational fluid dynamics method. Despite the great influence from the wind speeds, similar cell performance is obtained for the two cells under both windless and wind speed conditions when the wind parallels to the steam duct. Fan volumetric effectiveness which characterizes the fan performance, as well as the exchanger heat transfer rate, drops obviously with the increasing wind speed, and performance difference between the exchanger pair in the same A-frame also rises continuously. Furthermore, different flow and heat transfer characteristics of the windward and leeward cell are obtained at different wind angles, and ambient wind enhances the performance of the leeward cell, while that of the windward one changes little.

  10. Gas Engine-Driven Heat Pump Chiller for Air-Conditioning and Hot Water Supply Systems

    NASA Astrophysics Data System (ADS)

    Fujita, Toshihiko; Mita, Nobuhiro; Moriyama, Tadashi; Hoshino, Norimasa; Kimura, Yoshihisa

    In Part 1 of this study, the performance characteristics of a 457kW gas engine-driven heat pump (GHP) chiller have been obtained from a simulation model analysis for both cooling and heating modes and it has been found that the part-load characteristics of the GHP chiller are fairly well. On the back of Part 1, a computer simulation program has been developed for the evaluation of GHP chiller systems to compare with the other types of heat source systems for air-conditioning and hot water supply applications. The simulation program can be used to estimate annual energy consumption, annual CO2 emission, etc. of the systems with the data of monthly and hourly thermal loads on various buildings, outdoor air conditions, and characteristics of various components comprising the systems. By applying this to some cases of medium-scale hotel, office, shop, and hospital buildings, it has been found that the GHP chiller systems have advantages particularly in the cases of hotels and hospitals where a lot of hot water demand exists. It has also been found that the combination of a GHP chiller and a direct-fired absorption water chiller boiler (hot and chilled water generator) appears promising.

  11. Air Source Heat Pumps for Cold Climate Applications: Recent U. S. R&D Results from IEA HPP Annex 41

    SciTech Connect

    Baxter, Van D; Groll, Dr. Eckhard A.; Shen, Bo

    2014-01-01

    Air source heat pumps are easily applied to buildings almost anywhere. They are widespread in milder climate regions but their use in cold regions is hampered due to low efficiency and heating capacity at cold outdoor temperatures. This article describes selected R&D activities aimed at improving their cold weather performance.

  12. Vertical heat transfer based on direct microstructure measurements in the ice-free Pacific-side Arctic Ocean: the role and impact of the Pacific water intrusion

    NASA Astrophysics Data System (ADS)

    Kawaguchi, Y.; Kikuchi, T.; Inoue, R.

    2014-12-01

    This study quantifies diapycnal mixing and vertical heat transfer in the Pacific side of the Arctic Ocean, where sea-ice cover has disappeared between July and September in the last few decades. We conducted microstructure measurements in the open water region around the Canada Basin from late summer to fall in 2009 and 2010 using RV Mirai. In the study domain, the dissipation rate of turbulent kinetic energy, ɛ, is typically as low level as O(10-10) W kg-1, resulting in vertical heat diffusivity of O(10-7) m2 s-1, which is close to the molecular diffusivity of heat, suggesting comparatively little predominance of mechanical turbulent mixing. An exception is the case at the Barrow Canyon, where the strong baroclinic throughflow generates substantial vertical mixing, producing ɛ >O(10-7) W kg-1, because of the shear flow instability. Meanwhile, in the confluence region, where the warm/salty Pacific water and the cold/fresh Arctic basin water encounter, the micro-temperature profiles revealed a localized enhancement in vertical diffusivity of heat, reaching O(10-5) m2 s-1 or greater. In this region, an intrusion of warm Pacific water creates a horizontally interleaved structure, where the double-diffusive mixing facilitates vertical heat transfer between the intruding Pacific water and the surrounding basin waters.

  13. Simulations of sizing and comfort improvements for residential forced-air heating and cooling systems

    SciTech Connect

    Walker, I.S.; Degenetais, G.; Siegel, J.A.

    2002-05-01

    In many parts of North America residential HVAC systems are installed outside conditioned space. This leads to significant energy losses and poor occupant comfort due to conduction and air leakage losses from the air distribution ducts. In addition, cooling equipment performance is sensitive to air flow and refrigerant charge that have been found to be far from manufacturers specifications in most systems. The simulation techniques discussed in this report were developed in an effort to provide guidance on the savings potentials and comfort gains that can be achieved by improving ducts (sealing air leaks) and equipment (correct air-flow and refrigerant charge). The simulations include the complex air flow and thermal interactions between duct systems, their surroundings and the conditioned space. They also include cooling equipment response to air flow and refrigerant charge effects. Another key aspect of the simulations is that they are dynamic to account for cyclic losses from the HVAC system and the effect of cycle length on energy and comfort performance. To field test the effect of changes to residential HVAC systems requires extensive measurements to be made for several months for each condition tested. This level of testing is often impractical due to cost and time limitations. Therefore the Energy Performance of Buildings Group at LBNL developed a computer simulation tool that models residential HVAC system performance. This simulation tool has been used to answer questions about equipment downsizing, duct improvements, control strategies and climate variation so that recommendations can be made for changes in residential construction and HVAC installation techniques that would save energy, reduce peak demand and result in more comfortable homes. Although this study focuses on California climates, the simulation tool could easily be applied to other climates. This report summarizes the simulation tool and discusses the significant developments that allow

  14. An Analysis of Price Determination and Markups in the Air-Conditioning and Heating Equipment Industry

    SciTech Connect

    Dale, Larry; Millstein, Dev; Coughlin, Katie; Van Buskirk, Robert; Rosenquist, Gregory; Lekov, Alex; Bhuyan, Sanjib

    2004-01-30

    In this report we calculate the change in final consumer prices due to minimum efficiency standards, focusing on a standard economic model of the air-conditioning and heating equipment (ACHE) wholesale industry. The model examines the relationship between the marginal cost to distribute and sell equipment and the final consumer price in this industry. The model predicts that the impact of a standard on the final consumer price is conditioned by its impact on marginal distribution costs. For example, if a standard raises the marginal cost to distribute and sell equipment a small amount, the model predicts that the standard will raise the final consumer price a small amount as well. Statistical analysis suggest that standards do not increase the amount of labor needed to distribute equipment the same employees needed to sell lower efficiency equipment can sell high efficiency equipment. Labor is a large component of the total marginal cost to distribute and sell air-conditioning and heating equipment. We infer from this that standards have a relatively small impact on ACHE marginal distribution and sale costs. Thus, our model predicts that a standard will have a relatively small impact on final ACHE consumer prices. Our statistical analysis of U.S. Census Bureau wholesale revenue tends to confirm this model prediction. Generalizing, we find that the ratio of manufacturer price to final consumer price prior to a standard tends to exceed the ratio of the change in manufacturer price to the change in final consumer price resulting from a standard. The appendix expands our analysis through a typical distribution chain for commercial and residential air-conditioning and heating equipment.

  15. High-efficiency gas heat pump air-conditioner equipped with absorption refrigerator

    NASA Astrophysics Data System (ADS)

    Kawakami, Ryuichiro; Imai, Kazuya; Nakajima, Hidekazu; Okamoto, Hiroaki; Hihara, Eiji

    To improve rated efficiency and partial load efficiency of gas engine heat pump (GHP), we are developing a new type air-cooled absorption refrigerator which is driven by the engine waste hot water. To shape the compact absorption refrigerator body that was able to be built into the space of a GHP outdoor-unit, an air-cooled sub-cooled adiabatic absorber and flowing liquid film plate type generator were newly developed. Maximum cooling capacity was increased about 20%, rated load COP was increased 40%, and partial load COP was increased 46% or less, as a result of the combination examination of a prototype 8.0kW absorption refrigerator and a 56kW GHP at a laboratory.

  16. Study and Development of an Air Conditioning System Operating on a Magnetic Heat Pump Cycle

    NASA Technical Reports Server (NTRS)

    Wang, Pao-Lien

    1991-01-01

    This report describes the design of a laboratory scale demonstration prototype of an air conditioning system operating on a magnetic heat pump cycle. Design parameters were selected through studies performed by a Kennedy Space Center (KSC) System Simulation Computer Model. The heat pump consists of a rotor turning through four magnetic fields that are created by permanent magnets. Gadolinium was selected as the working material for this demonstration prototype. The rotor was designed to be constructed of flat parallel disks of gadolinium with very little space in between. The rotor rotates in an aluminum housing. The laboratory scale demonstration prototype is designed to provide a theoretical Carnot Cycle efficiency of 62 percent and a Coefficient of Performance of 16.55.

  17. Motion of Optically Heated Spheres at the Water-Air Interface.

    PubMed

    Girot, A; Danné, N; Würger, A; Bickel, T; Ren, F; Loudet, J C; Pouligny, B

    2016-03-22

    A micrometer-sized spherical particle classically equilibrates at the water-air interface in partial wetting configuration, causing about no deformation to the interface. In condition of thermal equilibrium, the particle just undergoes faint Brownian motion, well visible under a microscope. We report experimental observations when the particle is made of a light-absorbing material and is heated up by a vertical laser beam. We show that, at small laser power, the particle is trapped in on-axis configuration, similarly to 2-dimensional trapping of a transparent sphere by optical forces. Conversely, on-axis trapping becomes unstable at higher power. The particle escapes off the laser axis and starts orbiting around the axis. We show that the laser-heated particle behaves as a microswimmer with velocities on the order of several 100 μm/s with just a few milliwatts of laser power.

  18. Cost analysis of new and retrofit hot-air type solar assisted heating systems

    NASA Technical Reports Server (NTRS)

    Stewart, R. D.; Hawkins, B. J.

    1978-01-01

    A detailed cost analysis/cost improvement study was performed on two Department of Energy/National Aeronautics and Space Administration operational test sites to determine actual costs and potential cost improvements of new and retrofit hot air type, solar assisted heating and hot water systems for single family sized structures. This analysis concentrated on the first cost of a system which included procurement, installation, and integration of a solar assisted heating and hot water system on a new or retrofit basis; it also provided several cost projections which can be used as inputs to payback analyses, depending upon the degree of optimism or future improvements assumed. Cost definitions were developed for five categories of cost, and preliminary estimates were developed for each. The costing methodology, approach, and results together with several candidate low cost designs are described.

  19. Comfort air temperature influence on heating and cooling loads of a residential building

    NASA Astrophysics Data System (ADS)

    Stanciu, C.; Șoriga, I.; Gheorghian, A. T.; Stanciu, D.

    2016-08-01

    The paper presents the thermal behavior and energy loads of a two-level residential building designed for a family of four, two adults and two students, for different inside comfort levels reflected by the interior air temperature. Results are intended to emphasize the different thermal behavior of building elements and their contribution to the building's external load. The most important contributors to the building thermal loss are determined. Daily heating and cooling loads are computed for 12 months simulation in Bucharest (44.25°N latitude) in clear sky conditions. The most important aspects regarding sizing of thermal energy systems are emphasized, such as the reference months for maximum cooling and heating loads and these loads’ values. Annual maximum loads are encountered in February and August, respectively, so these months should be taken as reference for sizing thermal building systems, in Bucharest, under clear sky conditions.

  20. Mathematical equations for heat conduction in the fins of air-cooled engines

    NASA Technical Reports Server (NTRS)

    Harper, R R; Brown, W B

    1923-01-01

    The problem considered in this report is that of reducing actual geometrical area of fin-cooling surface, which is, of course, not uniform in temperature, to equivalent cooling area at one definite temperature, namely, that prevailing on the cylinder wall at the point of attachment of the fin. This makes it possible to treat all the cooling surface as if it were part of the cylinder wall and 100 per cent effective. The quantities involved in the equations are the geometrical dimensions of the fin, thermal conductivity of the material composing it, and the coefficient of surface heat dissipation between the fin and the air streams.

  1. Passive decay heat removal by natural air convection after severe accidents

    SciTech Connect

    Erbacher, F.J.; Neitzel, H.J.; Cheng, X.

    1995-09-01

    The composite containment proposed by the Research Center Karlsruhe and the Technical University Karlsruhe is to cope with severe accidents. It pursues the goal to restrict the consequences of core meltdown accidents to the reactor plant. One essential of this new containment concept is its potential to remove the decay heat by natural air convection and thermal radiation in a passive way. To investigate the coolability of such a passive cooling system and the physical phenomena involved, experimental investigations are carried out at the PASCO test facility. Additionally, numerical calculations are performed by using different codes. A satisfying agreement between experimental data and numerical results is obtained.

  2. Determination of Local Experimental Heat-Transfer Coefficients on Combustion Side of an Ammonia-Oxygen Rocket

    NASA Technical Reports Server (NTRS)

    Liebert, Curt H.; Ehlers, Robert C.

    1961-01-01

    Local experimental heat-transfer coefficients were measured in the chamber and throat of a 2400-pound-thrust ammonia-oxygen rocket engine with a nominal chamber pressure of 600 pounds per square inch absolute. Three injector configurations were used. The rocket engine was run over a range of oxidant-fuel ratio and chamber pressure. The injector that achieved the best performance also produced the highest rates of heat flux at design conditions. The heat-transfer data from the best-performing injector agreed well with the simplified equation developed by Bartz at the throat region. A large spread of data was observed for the chamber. This spread was attributed generally to the variations of combustion processes. The spread was least evident, however, with the best-performing injector.

  3. Recent progress in research pertaining to estimates of gas-side heat transfer in an aircraft gas turbine

    NASA Technical Reports Server (NTRS)

    Graham, Robert W.

    1989-01-01

    A decade ago several important fundamental heat transfer phenomena were identified which were considered basic to the ability to predict heat transfer loads in aircraft gas turbines. The progress in addressing these fundamentals over the past ten years is assessed. Much reseach effort has been devoted to their study in university, industry and government labs and significant progress has been achieved. Advances in computer technology have enabled the modeling of complex 3-D fluid flow in gas turbines so necessary for heat transfer calculations. Advances in instrumentation plus improved data acquisition have brought about more reliable data sets. While much has advanced in the 1980's, much challenging research remains to be done. Several of these areas are suggested.

  4. Gas heating effects on the formation and propagation of a microwave streamer in air

    NASA Astrophysics Data System (ADS)

    Kourtzanidis, Konstantinos; Rogier, François; Boeuf, Jean-Pierre

    2015-09-01

    The development of microwave plasma streamers at 110 GHz in atmospheric pressure air is numerically investigated taking into account the intense gas heating and its effects on the plasma formation and dynamics. The simulations are based on an implicit finite difference time domain formulation of Maxwell's equations coupled with a simple plasma fluid model and a real gas Euler equation solver. The numerical results show how the formation of a shock wave due to the large microwave power absorbed by the plasma and converted into gas heating strongly modifies the streamer elongation and dynamics. A microwave streamer filament stretches along its axis because of ionization-diffusion mechanisms in the enhanced electric field at the streamer tips. The change in the gas density distribution associated with the formation of shock wave due to gas heating strongly modifies the ionization and diffusion mechanisms and tends to limit the on-axis microwave streamer elongation by enhancing resonance effects. The simulations suggest that gas heating effects also play an important role in the observed bending or branching of microwave streamers after they have reached a critical length.

  5. Heating effects of a non-equilibrium RF corona discharge in atmospheric air

    NASA Astrophysics Data System (ADS)

    Auzas, F.; Tardiveau, P.; Puech, V.; Makarov, M.; Agneray, A.

    2010-12-01

    Electrical and thermal properties of a single electrode configuration corona discharge generated under radiofrequency high voltage inside an open air gap at pressures above 1 bar is investigated. Time-resolved imaging of the discharge shows a four-step development of the discharge at atmospheric pressure starting by streamers' inception and propagation, evolving in heating waves and stabilizing in a stationary regime until the power supply is switched off. The mean gas temperature reaches about 1700 K in tens of microseconds with electrical energy release around tens of millijoules. Heating has been attributed to ion collisions and excited species relaxation, promoted by the successive time periods of the power supply. At higher pressures, beyond 3 bar, this behaviour changes and heating occurs at the same time as the discharge propagates. It leads to hot channels which constrict near the electrode as long as the voltage pulse is applied. Temperature gets higher and saturates at 2600 K whatever the voltage and the pressure. Considering the change in the electrical energy density released within the plasma channels with pressure and voltage, temperature saturation seems to be an effect of heat confining within the channels due to pressure. The large and non-thermal plasma generated by the RF corona discharge is a very good candidate for car engine lean mixtures ignition issues.

  6. Downward flow of water with entrained air in a nonuniformaly heated subdivided annulus

    SciTech Connect

    Johnston, B.S.; May, C.P.

    1992-01-01

    This paper describes an experimental study in which water was fed to a vertical annulus, entraining air in downward flow. The annulus was subdivided by longitudinal fins into four subchannels and was heated with an azimuthally varying heat flux. A bypass was provided to simulate flow in parallel channels. For steady liquid flow, inlet temperature, and pressure boundary conditions, the power was increased until critical heat flux was reached. Overheating characteristics were grouped according to the prevailing flow pattern. In annular flows (j{sub L} < 0.3 m/s) overheating of the whole test section occurs when steam production causes countercurrent flooding. In intermittent flows (0.3 < j{sub L} < 0.9 m/s) the overheating is confined to a portion of the hot subchannel. The mechanism is postulated to be stagnation of a large bubble. In bubble flows (0.9 m/s < j{sub L}) overheating occurs by diverting inlet flow to the bypass and again involves the whole test section. Except at the very lowest flow rates, critical heat flux occurs when the effluent liquid temperature is below saturation.

  7. Downward flow of water with entrained air in a nonuniformaly heated subdivided annulus

    SciTech Connect

    Johnston, B.S.; May, C.P.

    1992-10-01

    This paper describes an experimental study in which water was fed to a vertical annulus, entraining air in downward flow. The annulus was subdivided by longitudinal fins into four subchannels and was heated with an azimuthally varying heat flux. A bypass was provided to simulate flow in parallel channels. For steady liquid flow, inlet temperature, and pressure boundary conditions, the power was increased until critical heat flux was reached. Overheating characteristics were grouped according to the prevailing flow pattern. In annular flows (j{sub L} < 0.3 m/s) overheating of the whole test section occurs when steam production causes countercurrent flooding. In intermittent flows (0.3 < j{sub L} < 0.9 m/s) the overheating is confined to a portion of the hot subchannel. The mechanism is postulated to be stagnation of a large bubble. In bubble flows (0.9 m/s < j{sub L}) overheating occurs by diverting inlet flow to the bypass and again involves the whole test section. Except at the very lowest flow rates, critical heat flux occurs when the effluent liquid temperature is below saturation.

  8. Two-dimensional simulation of the single-sided air-coupled ultrasonic pitch-catch technique for non-destructive testing.

    PubMed

    Delrue, Steven; Van Den Abeele, Koen; Blomme, Erik; Deveugele, Jurgen; Lust, Pieter; Matar, Olivier Bou

    2010-02-01

    Non-contact air-coupled ultrasonic inspection of materials using single-sided access offers interesting possibilities for the development of in-line non-destructive testing (NDT) systems. This contribution reports observations and simulations obtained from a single-sided air-coupled pitch-catch configuration. The pitch-catch technique involves a set-up in which transmitter and receiver are located at the same side of the test object. Sound waves, reflected once or multiple times from the back-wall of the object or refracted by a discontinuity, are recorded and analyzed for visualization. The feasibility of the technique is demonstrated, experimentally, in the case of artificial defects in aluminium samples. Depending on the configuration one or more ultrasonic images of the defect can be observed, their number and relative position containing information about the location of the defect. The experiments are simulated using two distinctive methods. The first simulation is based on a ray tracing (shadow) approach, the second method uses a spectral solution implemented within COMSOL. Both simulation methods allow simple prediction of the response images in experimental conditions with supplementary levels of complexity, which will assist the development and optimization of online inspection techniques.

  9. Microenvironmental air quality impact of a commercial-scale biomass heating system.

    PubMed

    Tong, Zheming; Yang, Bo; Hopke, Philip K; Zhang, K Max

    2017-01-01

    Initiatives to displace petroleum and climate change mitigation have driven a recent increase in space heating with biomass combustion. However, there is ample evidence that biomass combustion emits significant quantities of health damaging pollutants. We investigated the near-source micro-environmental air quality impact of a biomass-fueled combined heat and power system equipped with an electrostatic precipitator (ESP) in Syracuse, NY. Two rooftop sampling stations with PM2.5 and CO2 analyzers were established in such that one could capture the plume while the other one served as the background for comparison depending on the wind direction. Four sonic anemometers were deployed around the stack to quantify spatially and temporally resolved local wind patterns. Fuel-based emission factors were derived based on near-source measurement. The Comprehensive Turbulent Aerosol Dynamics and Gas Chemistry (CTAG) model was then applied to simulate the spatial variations of primary PM2.5 without ESP. Our analysis shows that the absence of ESP could lead to an almost 7 times increase in near-source primary PM2.5 concentrations with a maximum concentration above 100 μg m(-3) at the building rooftop. The above-ground "hotspots" would pose potential health risks to building occupants since particles could penetrate indoors via infiltration, natural ventilation, and fresh air intakes on the rooftop of multiple buildings. Our results demonstrated the importance of emission control for biomass combustion systems in urban area, and the need to take above-ground pollutant "hotspots" into account when permitting distributed generation. The effects of ambient wind speed and stack temperature, the suitability of airport meteorological data on micro-environmental air quality were explored, and the implications on mitigating near-source air pollution were discussed.

  10. Aerodynamic heating and the deflection of drops by an obstacle in an air stream in relation to aircraft icing

    NASA Technical Reports Server (NTRS)

    Kantrowitz, Arthur

    1940-01-01

    Two topics of interest to persons attempting to apply the heat method of preventing ice formation on aircraft are considered. Surfaces moving through air at high speed are shown, both theoretically and experimentally, to be subject to important aerodynamic heating effects that will materially reduce the heat required to prevent ice. Numerical calculations of the path of water drops in an air stream around a circular cylinder are given. From these calculations, information is obtained on the percentage of the swept area cleared of drops.

  11. Response of London's urban heat island to a marine air intrusion in an easterly wind regime

    NASA Astrophysics Data System (ADS)

    Chemel, C.; Sokhi, R. S.

    2010-09-01

    London is long known to develop a pronounced urban heat island (UHI) resulting primarily from the storage of heat in the urban fabric during the day and released during the night, the differences in thermal and radiative properties of the surface between urban and rural areas, and lack of evapotranspiration in urban areas. Under calm, clear, and dry weather conditions, the difference in near-surface air temperature between two representative urban centre and rural locations at a given time typically reaches several degrees (i.e. warming) during the night and can be negative (i.e. cooling) during the day. Like the majority of large cities in the world, London is located in a coastal area. On certain occasions cooler marine air from the North Sea is advected across London by a sea breeze or easterly winds. In our work we examine the effects of a marine air intrusion, in an easterly wind regime, on the structure of London's UHI for a case study on 7 May 2008. For this purpose, numerical simulations with the Weather Research and Forecast (WRF) model are performed for multiple nested domains with the innermost domain covering London and its rural surroundings at the kilometre scale. A sensitivity study is undertaken to assess how the categorisation of the urban land use and the parameterisation of the urban canopy in the model affect its performance characteristics for the near-surface air temperature field. The categorisation of the urban landuse, according to the fractional area that is built-up within each grid cell, is found to be key to capturing the spatial pattern of the temperature field. Using a multilayer rather than single layer urban canopy model improves the representation of the variability of the pattern and the intensity of the UHI. A notable outcome of this work is that the inclusion of building anthropogenic fluxes is comparatively less important as regards model performance for near-surface air temperature. The effects of the marine air intrusion on

  12. On the Potential Impact of Daytime Surface Sensible Heat Flux on the Dissipation of Martian Cold Air Outbreaks

    NASA Technical Reports Server (NTRS)

    Segal, M.; Arritt, R. W.; Tillman, J. E.

    1997-01-01

    The Martian daytime soil surface temperature is governed primarily by the net irradiance balance and surface soil heat flux. Thus the outbreak of a cold air mass generates increased sensible heat flux that is conducive to daytime dissipation of the cold air mass thermal characteristics. Conceptual and scaling evaluations of this dissipation are provided while comparison is made with similar situations on Earth. It is estimated that sensible heat flux contribution to the dissipation of the original thermal structure of the cold air could be three times larger than the corresponding situation on Earth. Illustrative numerical model simulations provide scaling of the potential impact on the dissipation of cold air masses for various combinations of background wind speed and latitudes.

  13. Shell-side distribution and the influence of inlet conditions in a model of a disc-and-doughnut heat exchanger

    NASA Astrophysics Data System (ADS)

    Founti, M. A.; Vardis, C.; Whitelaw, J. H.

    1985-09-01

    Measurements of wall pressure and of three orthogonal velocity components with their corresponding fluctuations are reported for two systems of alternating and equi-spaced doughnut and disc baffles axisymmetrically located in a water turbulent pipe flow, simulating the isothermal shell-side flow in shell and tube heat exchangers. The influence of inlet Reynolds number and of asymmetric inlet flow conditions was studied for two geometries. The velocity field was dominated by the pressure gradient and the flow around each individual baffle was influenced by the relative position of its neighbouring baffles.

  14. Shell-side distribution and the influence of inlet conditions in a model of a disc-and-doughnut heat exchanger

    NASA Astrophysics Data System (ADS)

    Founti, M. A.; Vafidis, C.; Whitelaw, J. H.

    Measurements of wall pressure and of three orthogonal velocity components with their corresponding fluctuations are reported for two systems of alternating and equi-spaced doughnut and disc baffles axisymmetrically located in a water turbulent pipe flow, simulating the isothermal shell-side flow in shell and tube heat exchangers. The influence of inlet Reynolds number and of asymmetric inlet flow conditions was studied for two geometries. The velocity field was dominated by the pressure gradients and the flow around each individual baffle was influenced by the relative position of its neighboring baffles.

  15. Air

    MedlinePlus

    ... do to protect yourself from dirty air . Indoor air pollution and outdoor air pollution Air can be polluted indoors and it can ... this chart to see what things cause indoor air pollution and what things cause outdoor air pollution! Indoor ...

  16. International Space Station Common Cabin Air Assembly Condensing Heat Exchanger Hydrophilic Coating Failures and Lessons Learned

    NASA Technical Reports Server (NTRS)

    Balistreri, Steven F.; Shaw, Laura A.; Laliberte, Yvon

    2010-01-01

    The ability to control the temperature and humidity of an environment or habitat is critical for human survival. These factors are important to maintaining human health and comfort, as well as maintaining mechanical and electrical equipment in good working order to support the human and to accomplish mission objectives. The temperature and humidity of the International Space Station (ISS) United States On-orbit Segment (USOS) cabin air is controlled by the Common Cabin Air Assembly (CCAA). The CCAA consists of a fan, a condensing heat exchanger (CHX), an air/water separator, temperature and liquid sensors, and electrical controlling hardware and software. The CHX is the primary component responsible for control of temperature and humidity. The CCAA CHX contains a chemical coating that was developed to be hydrophilic and thus attract water from the humid influent air. This attraction forms the basis for water removal and therefore cabin humidity control. However, there have been several instances of CHX coatings becoming hydrophobic and repelling water. When this behavior is observed in an operational CHX, the unit s ability to remove moisture from the air is compromised and the result is liquid water carryover into downstream ducting and systems. This water carryover can have detrimental effects on the cabin atmosphere quality and on the health of downstream hardware. If the water carryover is severe and widespread, this behavior can result in an inability to maintain humidity levels in the USOS. This paper will describe the operation of the five CCAAs within in the USOS, the potential causes of the hydrophobic condition, and the impacts of the resulting water carryover to downstream systems. It will describe the history of this behavior and the actual observed impacts to the ISS USOS. Information on mitigation steps to protect the health of future CHX hydrophilic coatings and potential remediation techniques will also be discussed.

  17. Effect of heating-ventilation-air conditioning system sanitation on airborne fungal populations in residential environments.

    PubMed

    Garrison, R A; Robertson, L D; Koehn, R D; Wynn, S R

    1993-12-01

    Commercial air duct sanitation services are advertised to the public as being effective in reducing indoor aeroallergen levels despite the absence of published supporting data. Eight residential heat-ventilation-air conditioning (HVAC) systems in six homes and seven HVAC systems in five homes in winter and summer, respectively, were sampled to determine fungal colony forming units (CFUs) prior to and after an HVAC sanitation procedure was performed by a local company. Two houses in which no sanitation procedure was performed served as controls in each study phase. Two sample sets were obtained at each HVAC system prior to cleaning in order to determine baseline CFU levels. The test HVAC systems were then cleaned, and the HVAC systems allowed to operate as desired by the residents. Posttreatment sampling was performed 48 hours and then weekly after cleaning for 8 weeks. The HVAC systems were analyzed by exposing sterile 2% malt extract media plates at a 90-degree angle to the air flow at the air supply and air return vents. The baseline CFUs were similar in the control and study houses. Eight weeks after sanitation, the study houses demonstrated an overall CFU reduction of 92% during winter and 84% during summer. No reduction in CFU values was observed over the 8-week study period for the houses selected as controls. Further, HVAC sanitation appeared to reduce the number of fungal colonies entering and leaving the HVAC system, suggesting that the HVAC contained a significant percentage of the total fungal load in these homes. These data suggest that HVAC sanitation may be an effective tool in reducing airborne fungal populations in residential environments.

  18. Heating, ventilating, and air conditioning deactivation thermal analysis of PUREX Plant

    SciTech Connect

    Chen, W.W.; Gregonis, R.A.

    1997-08-01

    Thermal analysis was performed for the proposed Plutonium Uranium Extraction Plant exhaust system after deactivation. The purpose of the analysis was to determine if enough condensation will occur to plug or damage the filtration components. A heat transfer and fluid flow analysis was performed to evaluate the thermal characteristics of the underground duct system, the deep-bed glass fiber filter No. 2, and the high-efficiency particulate air filters in the fourth filter building. The analysis is based on extreme variations of air temperature, relative humidity, and dew point temperature using 15 years of Hanford Site weather data as a basis. The results will be used to evaluate the need for the electric heaters proposed for the canyon exhaust to prevent condensation. Results of the analysis indicate that a condition may exist in the underground ductwork where the duct temperature can lead or lag changes in the ambient air temperature. This condition may contribute to condensation on the inside surfaces of the underground exhaust duct. A worst case conservative analysis was performed assuming that all of the water is removed from the moist air over the inside surface of the concrete duct area in the fully developed turbulent boundary layer while the moist air in the free stream will not condense. The total moisture accumulated in 24 hours is negligible. Water puddling would not be expected. The results of the analyses agree with plant operating experiences. The filters were designed to resist high humidity and direct wetting, filter plugging caused by slight condensation in the upstream duct is not a concern. 19 refs., 2 figs.

  19. Numerical Investigation of Radiative Heat Transfer in Laser Induced Air Plasmas

    NASA Technical Reports Server (NTRS)

    Liu, J.; Chen, Y. S.; Wang, T. S.; Turner, James E. (Technical Monitor)

    2001-01-01

    Radiative heat transfer is one of the most important phenomena in the laser induced plasmas. This study is intended to develop accurate and efficient methods for predicting laser radiation absorption and plasma radiative heat transfer, and investigate the plasma radiation effects in laser propelled vehicles. To model laser radiation absorption, a ray tracing method along with the Beer's law is adopted. To solve the radiative transfer equation in the air plasmas, the discrete transfer method (DTM) is selected and explained. The air plasma radiative properties are predicted by the LORAN code. To validate the present nonequilibrium radiation model, several benchmark problems are examined and the present results are found to match the available solutions. To investigate the effects of plasma radiation in laser propelled vehicles, the present radiation code is coupled into a plasma aerodynamics code and a selected problem is considered. Comparisons of results at different cases show that plasma radiation plays a role of cooling plasma and it lowers the plasma temperature by about 10%. This change in temperature also results in a reduction of the coupling coefficient by about 10-20%. The present study indicates that plasma radiation modeling is very important for accurate modeling of aerodynamics in a laser propelled vehicle.

  20. Air gasification of rice husk in bubbling fluidized bed reactor with bed heating by conventional charcoal.

    PubMed

    Makwana, J P; Joshi, Asim Kumar; Athawale, Gaurav; Singh, Dharminder; Mohanty, Pravakar

    2015-02-01

    An experimental study of air gasification of rice husk was conducted in a bench-scale fluidized bed gasifier (FBG) having 210 mm diameter and 1600 mm height. Heating of sand bed material was performed using conventional charcoal fuel. Different operating conditions like bed temperature, feeding rate and equivalence ratio (ER) varied in the range of 750-850 °C, 25-31.3 kg/h, and 0.3-0.38, respectively. Flow rate of air was kept constant (37 m(3)/h) during FBG experiments. The carbon conversion efficiencies (CCE), cold gas efficiency, and thermal efficiency were evaluated, where maximum CCE was found as 91%. By increasing ER, the carbon conversion efficiency was decreased. Drastic reduction in electric consumption for initial heating of gasifier bed with charcoal compared to ceramic heater was ∼45%. Hence rice husk is found as a potential candidate to use directly (without any processing) in FBG as an alternative renewable energy source from agricultural field.

  1. Field Test of High Efficiency Residential Buildings with Ground-source and Air-source Heat Pump Systems

    SciTech Connect

    Ally, Moonis Raza; Munk, Jeffrey D; Baxter, Van D

    2011-01-01

    This paper describes the field performance of space conditioning and water heating equipment in four single-family residential structures with advanced thermal envelopes. Each structure features a different, advanced thermal envelope design: structural insulated panel (SIP); optimum value framing (OVF); insulation with embedded phase change materials (PCM) for thermal storage; and exterior insulation finish system (EIFS). Three of the homes feature ground-source heat pumps (GSHPs) for space conditioning and water heating while the fourth has a two-capacity air-source heat pump (ASHP) and a heat pump water heater (HPWH). Two of the GCHP-equipped homes feature horizontal ground heat exchange (GHX) loops that utillize the existing foundation and utility service trenches while the third features a vertical borehole with vertical u-tube GHX. All of the houses were operated under the same simulated occupancy conditions. Operational data on the house HVAC/Water heating (WH) systems are presented and factors influencing overall performance are summarized.

  2. Measurement of the Effectiveness of Concave Spherical Dimples for the Enhancement of Hot-gas Side Heat Transfer

    DTIC Science & Technology

    2011-01-31

    Nomenclature d = Dim ple diameter h = Dimple depth H = Channel height f = Fraction of surface covered by dimples t = Dimple spacing Nu = Nusselt number ...2000) examined the effect of channel height on Nusselt number for a staggered pattern of CSD with h/d=0.19 and f=0.57. The globally averaged heat...described the flow patterns and measured local Nusselt number distributions over the surface for the same dimple pattern used by Moon. The most important

  3. Measurements of the Effectiveness of Concave Spherical Dimples for Enhancement of Hot-gas Side Heat Transfer

    DTIC Science & Technology

    2009-06-02

    Fraction of surface covered by dimples t = Dimple spacing Nu = Nusselt number Pc = Chamber pressure I. Introduction n an expander cycle rocket engine...channel height on Nusselt number for a staggered pattern of CSD with h/d=0.19 and f=0.57. The globally averaged heat transfer enhancement, Nudimple...measured local Nusselt number distributions over the surface for the same dimple pattern used by Moon. The most important features of the flow consisted

  4. Advances in the Lightweight Air-Liquid Composite Heat Exchanger Development for Space Exploration Applications

    NASA Technical Reports Server (NTRS)

    Shin, E. Eugene; Johnston, J. Chris; Haas, Daniel

    2011-01-01

    An advanced, lightweight composite modular Air/Liquid (A/L) Heat Exchanger (HX) Prototype for potential space exploration thermal management applications was successfully designed, manufactured, and tested. This full-scale Prototype consisting of 19 modules, based on recommendations from its predecessor Engineering Development unit (EDU) but with improved thermal characteristics and manufacturability, was 11.2 % lighter than the EDU and achieves potentially a 42.7% weight reduction from the existing state-of-the-art metallic HX demonstrator. However, its higher pressure drop (0.58 psid vs. 0.16 psid of the metal HX) has to be mitigated by foam material optimizations and design modifications including a more systematic air channel design. Scalability of the Prototype design was validated experimentally by comparing manufacturability and performance between the 2-module coupon and the 19-module Prototype. The Prototype utilized the thermally conductive open-cell carbon foam material but with lower density and adopted a novel high-efficiency cooling system with significantly increased heat transfer contact surface areas, improved fabricability and manufacturability compared to the EDU. Even though the Prototype was required to meet both the thermal and the structural specifications, accomplishing the thermal requirement was a higher priority goal for this first version. Overall, the Prototype outperformed both the EDU and the corresponding metal HX, particularly in terms of specific heat transfer, but achieved 93.4% of the target. The next generation Prototype to achieve the specification target, 3,450W would need 24 core modules based on the simple scaling factor. The scale-up Prototype will weigh about 14.7 Kg vs. 21.6 Kg for the metal counterpart. The advancement of this lightweight composite HX development from the original feasibility test coupons to EDU to Prototype is discussed in this paper.

  5. Advanced variable speed air source integrated heat pump (AS-IHP) development - CRADA final report

    SciTech Connect

    Baxter, Van D.; Rice, C. Keith; Munk, Jeffrey D.; Ally, Moonis Raza; Shen, Bo

    2015-09-30

    Between August 2011 and September 2015, Oak Ridge National Laboratory (ORNL) and Nordyne, LLC (now Nortek Global HVAC LLC, NGHVAC) engaged in a Cooperative Research and Development Agreement (CRADA) to develop an air-source integrated heat pump (AS-IHP) system for the US residential market. Two generations of laboratory prototype systems were designed, fabricated, and lab-tested during 2011-2013. Performance maps for the system were developed using the latest research version of the DOE/ORNL Heat Pump Design Model, or HPDM, (Rice 1991; Rice and Jackson 2005; Shen et al 2012) as calibrated against the lab test data. These maps were the input to the TRNSYS (SOLAR Energy Laboratory, et al, 2010) system to predict annual performance relative to a baseline suite of equipment meeting minimum efficiency standards in effect in 2006 (combination of 13 SEER air-source heat pump (ASHP) and resistance water heater with Energy Factor (EF) of 0.9). Predicted total annual energy savings, while providing space conditioning and water heating for a tight, well insulated 2600 ft2 (242 m2) house at 5 U.S. locations, ranged from 46 to 61%, averaging 52%, relative to the baseline system (lowest savings at the cold-climate Chicago location). Predicted energy use for water heating was reduced 62 to 76% relative to resistance WH. Based on these lab prototype test and analyses results a field test prototype was designed and fabricated by NGHVAC. The unit was installed in a 2400 ft2 (223 m2) research house in Knoxville, TN and field tested from May 2014 to April 2015. Based on the demonstrated field performance of the AS-IHP prototype and estimated performance of a baseline system operating under the same loads and weather conditions, it was estimated that the prototype would achieve ~40% energy savings relative to the minimum efficiency suite. The estimated WH savings were >60% and SC mode savings were >50%. But estimated SH savings were only about 20%. It is believed that had the test

  6. Air-to-Water Heat Pumps With Radiant Delivery in Low-Load Homes

    SciTech Connect

    Backman, C.; German, A.; Dakin, B.; Springer, D.

    2013-12-01

    Space conditioning represents nearly 50% of average residential household energy consumption, highlighting the need to identify alternative cost-effective, energy-efficient cooling and heating strategies. As homes are better built, there is an increasing need for strategies that are particularly well suited for high performance, low load homes. ARBI researchers worked with two test homes in hot-dry climates to evaluate the in-situ performance of air-to-water heat pump (AWHP) systems, an energy efficient space conditioning solution designed to cost-effectively provide comfort in homes with efficient, safe, and durable operation. Two monitoring projects of test houses in hot-dry climates were initiated in 2010 to test this system. Both systems were fully instrumented and have been monitored over one year to capture complete performance data over the cooling and heating seasons. Results are used to quantify energy savings, cost-effectiveness, and system performance using different operating modes and strategies. A calibrated TRNSYS model was developed and used to evaluate performance in various climate regions. This strategy is most effective in tight, insulated homes with high levels of thermal mass (i.e. exposed slab floors).

  7. Air-to-Water Heat Pumps With Radiant Delivery in Low-Load Homes

    SciTech Connect

    Backman, C.; German, A.; Dakin, B.; Springer, D.

    2013-12-01

    Space conditioning represents nearly 50% of average residential household energy consumption, highlighting the need to identify alternative cost-effective, energy-efficient cooling and heating strategies. As homes are better built, there is an increasing need for strategies that are particularly well suited for high performance, low load homes. ARBI researchers worked with two test homes in hot-dry climates to evaluate the in-situ performance of air-to-water heat pump systems, an energy efficient space conditioning solution designed to cost-effectively provide comfort in homes with efficient, safe, and durable operation. Two monitoring projects of test houses in hot-dry climates were initiated in 2010 to test this system. Both systems were fully instrumented and have been monitored over one year to capture complete performance data over the cooling and heating seasons. Results are used to quantify energy savings, cost-effectiveness, and system performance using different operating modes and strategies. A calibrated TRNSYS model was developed and used to evaluate performance in various climate regions. This strategy is most effective in tight, insulated homes with high levels of thermal mass (i.e. exposed slab floors).

  8. Diffusive-to-ballistic transition of the modulated heat transport in a rarefied air chamber

    NASA Astrophysics Data System (ADS)

    Gomez-Heredia, C. L.; Macias, J.; Ordonez-Miranda, J.; Ares, O.; Alvarado-Gil, J. J.

    2017-01-01

    Modulated heat transfer in air subject to pressures from 760 Torr to 10-4 Torr is experimentally studied by means of a thermal-wave resonant cavity placed in a vacuum chamber. This is done through the analysis of the amplitude and phase delay of the photothermal signal as a function of the cavity length and pressure through of the Knudsen's number. The viscous, transitional, and free molecular regimes of heat transport are observed for pressures P>1.5 Torr, 25 mTorrheat transport.

  9. Experimental validation of coupled heat, air and moisture transfer modeling in multilayer building components

    NASA Astrophysics Data System (ADS)

    Ferroukhi, M. Y.; Abahri, K.; Belarbi, R.; Limam, K.; Nouviaire, A.

    2016-10-01

    The present paper lies to study the coupled heat, air and moisture transfer in multi-layer building materials. Concerning the modeling part, the interest is to predict the hygrothermal behavior, by developing a macroscopic model that incorporates simultaneously the diffusive, convective and conductive effects on the building elements. Heat transfer is considered in the strongly coupled situation where the mass and heat flux are temperature, vapor pressure and total pressure dependents. The model input parameters are evaluated experimentally through the development of various experimental prototypes in the laboratory. Thereafter, an experimental setup has been established in order to evaluate the hygrothermal process of several multilayer walls configurations. The experimental procedure consists to follow the temperature and relative humidity evolutions within the samples thickness, submitted to controlled and fixed boundary conditions. This procedure points out diverging conclusion between different testing materials combinations (e.g. red-brick and polystyrene). In fact, the hygrothermal behavior of the tested configurations is completely dependent on both materials selection and their thermophysical properties. Finally, comparison between numerical and experimental results showed good agreement with acceptable errors margins with an average of 3 %.

  10. Effect of heat waves on VOC emissions from vegetation and urban air quality

    NASA Astrophysics Data System (ADS)

    Churkina, G.; Kuik, F.; Lauer, A.; Bonn, B.; Butler, T. M.

    2015-12-01

    Programs to plant millions of trees in cities around the world aim at the reduction of summer temperatures, increase carbon storage, storm water control, provision of space for recreation, as well as poverty alleviation. Although these multiple benefits speak positively for urban greening programs, the programs do not take into account how close human and natural systems are coupled in urban areas. Elevated temperatures together with anthropogenic emissions of air and water pollutants distinguish the urban system. Urban and sub-urban vegetation responds to ambient changes and reacts with pollutants. Neglecting this coupling may lead to unforeseen drawbacks of urban greening programs. The potential for emissions of volatile organic compounds (VOC) from vegetation combined with anthropogenic emissions to produce ozone has long been recognized. This potential increases under rising temperatures. Here we investigate how heat waves affect emissions of VOC from urban vegetation and corresponding ground-level ozone. In this study we use Weather Research and Forecasting Model with coupled atmospheric chemistry (WRF-CHEM) to quantify these feedbacks in Berlin, Germany during the 2006 heat wave. VOC emissions from vegetation are simulated with MEGAN 2.0 coupled with WRF-CHEM. Our preliminary results indicate that contribution of VOCs from vegetation to ozone formation may increase by more than twofold during the heat wave period. We highlight the importance of the vegetation for urban areas under changing climate and discuss associated tradeoffs.

  11. T & I--Air Conditioning, Refrigeration, and Heating--Heating Units. Kit No. 87. Instructor's Manual [and] Student Learning Activity Guide.

    ERIC Educational Resources Information Center

    Simmons, Mike

    An instructor's manual and student activity guide on air conditioning, refrigeration, and heating units are provided in this set of prevocational education materials which focuses on the vocational area of trade and industry. (This set of materials is one of ninety-two prevocational education sets arranged around a cluster of seven vocational…

  12. Air Pollution in Moscow Region and Kiev during Heat Wave in July-August 2010

    NASA Astrophysics Data System (ADS)

    Zvyagintsev, A. M.; Tarasova, O. A.; Belikov, I. B.; Blum, O. B.; Elansky, N. F.; Kuznetsova, I. N.; Shumsky, R. A.

    2010-12-01

    when the maximum hourly averaged surface ozone and CO mixing ratios were up to 238 ppb and 30 ppm, respectively. Thresholds were also exceeded for NO, NO2 and PM10. Air composition in the Moscow region in summer 2010 was compared to the one in 2002. The latter was also affected by big forest and peat fires to the east of Moscow. In Kiev surface ozone and NOx mixing ratios during the heat wave only slightly exceeded the ones typical for this period of the year. A conclusion was made on the impact and contribution of the biomass burning products and secondary pollutants on the abrupt air quality decrease in the Moscow region in summer 2010.

  13. Solid oxide fuel cell power plant having a fixed contact oxidation catalyzed section of a multi-section cathode air heat exchanger

    DOEpatents

    Saito, Kazuo; Lin, Yao

    2015-02-17

    The multi-section cathode air heat exchanger (102) includes at least a first heat exchanger section (104), and a fixed contact oxidation catalyzed section (126) secured adjacent each other in a stack association. Cool cathode inlet air flows through cool air channels (110) of the at least first (104) and oxidation catalyzed sections (126). Hot anode exhaust flows through hot air channels (124) of the oxidation catalyzed section (126) and is combusted therein. The combusted anode exhaust then flows through hot air channels (112) of the first section (104) of the cathode air heat exchanger (102). The cool and hot air channels (110, 112) are secured in direct heat exchange relationship with each other so that temperatures of the heat exchanger (102) do not exceed 800.degree. C. to minimize requirements for using expensive, high-temperature alloys.

  14. Numerical modeling and simulation of hot air jet anti-icing system employing channels for enhanced heat transfer

    NASA Astrophysics Data System (ADS)

    Ahmed, Kamran Zaki

    Aircraft icing is a serious concern for the aviation community since it is one of the major causes of fatal aircraft accidents. Aircrafts use different anti-icing systems and one such system is the hot-air anti-icing system, which utilizes hot-air from the engine compressor bleed to heat critical aircraft surfaces and prevent ice formation. Numerous experimental and numerical studies have been performed to increase the efficiency of the hot-air jet based anti-icing systems. Most of the investigations have focused on either orifice design or the impingement region of target surface geometry. Since the impingement surface heat transfer drops off sharply past the stagnation region, investigators have studied the use of multiple jets to enhance surface heat transfer over a larger area. However, use of multiple jets is a further strain on engine resources. One way to conserve engine resources is to use single jet in conjunction with various geometric and physical mechanisms to enhance heat transfer. The current study focuses on enhancing heat transfer using a single jet and a channel. The study investigates the effect of channel's height, inlet location and Reynolds number on heat transfer characteristics in terms of average Nusselt number distribution along the impingement surface. The commercial CFD code, FLUENT, is used to simulate the different cases. Results indicate that the heat transfer depends strongly on height and width of channel, jet-to-target spacing, inlet angle and jet Reynolds number.

  15. Convection of Paramagnetic Fluid in a Cube Heated and Cooled from Side Walls and Placed below a Superconducting Magnet

    NASA Astrophysics Data System (ADS)

    Bednarz, Tomasz; Fornalik, Elzbieta; Tagawa, Toshio; Ozoe, Hiroyuki; Szmyd, Janusz S.

    The magnetic convection of paramagnetic fluid is studied in a strong magnetic field. The fluid in a cubic enclosure is heated from one vertical wall and cooled from the opposite one. The fluid is the 80% mass aqueous solution of glycerol with 0.8 mol/kg concentration of gadolinium nitrate hexahydrate to make the working fluid paramagnetic. The small amount of liquid crystal slurry is added to the fluid in order to visualize the temperature profiles in a vertical cross-section. This system is placed directly below the solenoid of the superconducting magnet which is oriented vertically. The temperature of cold wall is constantly controlled by the water flowing from a thermostating bath. On the other hand, the hot wall is heated by a nichrome wire from a DC power supply. In the numerical computations, the configuration of the system is modeled to be as close as possible to the real system. The physical properties of the working fluid are used to compute dimensionless parameters in the numerical model and the computations are carried out for corresponding cases. Later, the numerical and experimental results are compared with each other.

  16. Modification of the titanium nickelide surface using frictional treatment and subsequent heating in air

    NASA Astrophysics Data System (ADS)

    Korshunov, L. G.; Pushin, V. G.; Chernenko, N. L.

    2012-06-01

    The effect of a combined treatment including severe plastic deformation under the conditions of dry sliding friction and heating in air to temperatures of 300-480°C (holding for 1 h) on the structure and wear resistance of the surface layer of the Ti49.4Ni50.6 alloy has been investigated. It has been shown that this frictional treatment results in an amorphous-nanocrystalline structure in the surface layer (of thickness to 10 μm) of the Ti49.4Ni50.6 alloy. Heating to 300°C brings about the complete crystallization of the amorphous phase; as a result, the structure of the deformed surface layer of the alloy becomes single-phase, consisting of nanocrystals of the B2 phase. At 400°C, in this deformed surface layer there arises a nanocrystalline oxide (TiO2) phase whose amount reaches tens of volume percent. The sizes of crystals of the B2 phase and oxide TiO2 are in the range of 1-50 nm. The arising two-phase ( B2 + TiO2) nanocrystalline structure is located just below the oxide TiO2 film, which is less than 1 μm thick. With an increase in the heating temperature to 480°C, the deformed surface layer under consideration retains the nanocrystalline two-phase ( B2 + TiO2) structure, but an increase in the amount of the oxide phase and a decrease in the microhardness of this structure are observed. In some cases (heating at temperatures of 430 and 450°C), the presence of the two-phase ( B2 + TiO2) nanocrystalline surface layer leads to a noticeable (to ˜25%) enhancement in the adhesive wear resistance of the Ti49.4Ni50.6 alloy upon sliding friction in pair with steel 40Kh13.

  17. Recent changes in air temperature, heat waves occurrences, and atmospheric circulation in Northern Africa

    NASA Astrophysics Data System (ADS)

    Fontaine, Bernard; Janicot, Serge; Monerie, Paul-Arthur

    2013-08-01

    study documents the time evolution of air temperature and heat waves occurrences over Northern Africa for the period 1979-2011. A significant warming (1°-3°C), appearing by the mid-1960s over Sahara and Sahel, is associated with higher/lesser frequency of warm/cold temperatures, as with longer duration and higher occurrences of heat waves. Heat waves episodes of at least 4 day duration have been examined after removing the long-term evolution. These episodes are associated with specific anomalies: (i) in spring, positive low-level temperature anomalies over the Sahel and Sahara; low and midlevel cyclonic rotation over Morocco associated with a Rossby wave pattern, lessening the Harmattan; more/less atmospheric moisture westward/eastward to 0°; upward/downward anomalies above the western/eastern regions associated with the Rossby wave pattern; (ii) in summer, a similar but weaker positive low-level temperature anomaly (up to 3°C); less moisture westward to 10°W, a cyclonic anomaly in central Sahel favoring the monsoon eastward to 0° and a midlevel anticyclonic anomaly over the Western Sahara, increasing southward the flux divergence associated with the African Easterly Jet. In March-May, two to three heat waves propagate eastward. They are preceded by an abnormal warm cell over Libya and southwesterlies over the West Sahara. A large trough stands over North Atlantic while midtropospheric subsidence and anticyclonic rotation reinforce over the continent, then migrates toward the Arabian peninsula in breaking up. These signals are spatially coherent and might suggest the role of short Rossby waves with an eastward group velocity and a baroclinic mode, possibly associated with jet stream deformation.

  18. A randomised controlled trial of the electric heating pad vs forced-air warming for preventing hypothermia during laparotomy.

    PubMed

    Leung, K K; Lai, A; Wu, A

    2007-06-01

    A randomised controlled trial was conducted to compare the efficacy of upper body forced-air warming (Bair Hugger, Augustine Medical model 500/OR, Prairie, MN) with that of an electric heating pad (Operatherm 202, KanMed, Bromma, Sweden) for maintenance of intra-operative body temperature in 60 patients undergoing laparotomy under general anaesthesia. The nasopharyngeal temperature was recorded throughout the operative period. The mean (SD) final temperatures were 36.2 (0.4) degrees C with forced-air warming and 35.5 (1.0) degrees C with electric heating pad (p < 0.01). Upper body forced-air warming is more effective than the heating pad for maintenance of body temperature during laparotomy.

  19. IMPACT OF HEATING AND AIR CONDITIONING SYSTEM OPERATION AND LEAKAGE ON VENTILATION AND INTERCOMPARTMENT TRANSPORT: STUDIES IN UNOCCUPIED AND OCCUPIED TENNESSEE VALLEY HOMES

    EPA Science Inventory

    Forced-air heating and air conditioning (HAC) systems caused an average and maximum increase in air infiltration rates of 1.8- and 4.3-fold, respectively, during brief whole-house studies of tracer gas decay In 39 occupied houses. An average Increase in air infiltration rate of 0...

  20. Air leak seal for lung dissection plane with diode laser irradiation: monitoring heat-denature with auto-fluorescence

    NASA Astrophysics Data System (ADS)

    Gotoh, Maya; Arai, Tsunenori

    2008-02-01

    We studied the monitoring of heat-denature by autofluorescence spectrum from lung dissection plane during laser air leak sealing procedure. In order to seal the air leakage from lung in thoracotomy, we proposed novel laser sealing method with the combination of the diode laser (810nm wavelength) irradiation and indocyanine green staining (peak absorption wavelength: 805 nm). This sealing method is expected to preserve the postoperative ventilatory capacity and achieve minimally invasive surgery. We previously reported that this laser sealing only requires thin sealing margin (less than 300 μm in thickness) compared with that of the suturing or stapling. The most serious issue on the laser air leak sealing might be re-air-leakage due to rigid surface layer caused by excessive heat-denature, such as carbonization. We should achieve laser air leak sealing minimizing the degree of heat denature. Dissection planes of isolated porcine lung with /without the diode laser irradiation were prepared as samples. We measured the auto-fluorescence from these samples using a spectrometer. When the diode laser was irradiated with 400J/cm2, the surface of diode laser irradiated lung was fully carbonized. The ration of auto-fluorescence emission of 450nm / 500 nm, with 280 nm excitation wavelength was decreased less tha 50 % of initial value. That of 600 nm / 500 nm was increased over 700 % of initial value. The decreasing of the 450 nm auto-fluorescence intensity might be attributed to the heat-denaturing of the interstitial collagen in lung. However, increasing of the 600 nm didn't specify the origins, we suppose it might be originated from heat-denature substance, like carbonization. We could establish the useful monitoring for lung heat-denaturing with simple methodology. We think the auto-fluorescence measurement can be helpful not only for understanding the sealing mechanism, but also for controlling the degree of heat-denaturing during the procedure.

  1. The sensitivity of latent heat flux to the air humidity approximations used in ocean circulation models

    NASA Technical Reports Server (NTRS)

    Liu, W. Timothy; Niiler, Pearn P.

    1990-01-01

    In deriving the surface latent heat flux with the bulk formula for the thermal forcing of some ocean circulation models, two approximations are commonly made to bypass the use of atmospheric humidity in the formula. The first assumes a constant relative humidity, and the second supposes that the sea-air humidity difference varies linearly with the saturation humidity at sea surface temperature. Using climatological fields derived from the Marine Deck and long time series from ocean weather stations, the errors introduced by these two assumptions are examined. It is shown that the errors reach above 100 W/sq m over western boundary currents and 50 W/sq m over the tropical ocean. The two approximations also introduce erroneous seasonal and spatial variabilities with magnitudes over 50 percent of the observed variabilities.

  2. Heat Transfer Enhancement in Solar Air Heater Duct Fitted With Punched Hole Delta Winglets

    NASA Astrophysics Data System (ADS)

    Warrier, Hithesh. U.; Kotebavi, Vinod. M.

    2016-09-01

    This paper investigates the thermal performance of solar air heater fitted with delta winglet type vortex generators with holes punched on it by experimental and numerical analysis. Delta winglet type vortex generators having holes punched onto it are fitted in a duct of size 400*300*30mm.it is placed in duct in 3 different configurations, as an array having 5 pair in one row. Delta winglet pair has an attack angle of 30degree, with height of winglet equal to half of duct height. The study is done for Reynolds's no in the range of 9000 to 25000. Thermal performance is evaluated by analyzing both friction factor and Nussult's number using Webb's correlation for surface roughness. Numerical simulation is done using Ansys fluent. Experimental and numerical results are then compared. Results shows that heat transfer enhancement of about 20-150% can be achieved by using punched hole delta winglet.

  3. Vacuum-Induction, Vacuum-Arc, and Air-Induction Melting of a Complex Heat-Resistant Alloy

    NASA Technical Reports Server (NTRS)

    Decker, R. F.; Rowe, John P.; Freeman, J. W.

    1959-01-01

    The relative hot-workability and creep-rupture properties at 1600 F of a complex 55Ni-20Cr-15Co-4Mo-3Ti-3Al alloy were evaluated for vacuum-induction, vacuum-arc, and air-induction melting. A limited study of the role of oxygen and nitrogen and the structural effects in the alloy associated with the melting process was carried out. The results showed that the level of boron and/or zirconium was far more influential on properties than the melting method. Vacuum melting did reduce corner cracking and improve surface during hot-rolling. It also resulted in more uniform properties within heats. The creep-rupture properties were slightly superior in vacuum heats at low boron plus zirconium or in heats with zirconium. There was little advantage at high boron levels and air heats were superior at high levels of boron plus zirconium. Vacuum heats also had fewer oxide and carbonitride inclusions although this was a function of the opportunity for separation of the inclusions from high oxygen plus nitrogen heats. The removal of phosphorous by vacuum melting was not found to be related to properties. Oxygen plus nitrogen appeared to increase ductility in creep-rupture tests suggesting that vacuum melting removes unidentified elements detrimental to ductility. Oxides and carbonitrides in themselves did not initiate microcracks. Carbonitrides in the grain boundaries of air heats did initiate microcracks. The role of microcracking from this source and as a function of oxygen and nitrogen content was not clear. Oxygen and nitrogen did intensify corner cracking during hot-rolling but were not responsible for poor surface which resulted from rolling heats melted in air.

  4. Design Optimization and the Limits of Steady-State Heating Efficiency for Conventional Single-Speed Air-Source Heat Pumps

    SciTech Connect

    Rice, C.K.

    2001-06-06

    The ORNL Heat Pump Model and an optimizing program were used to explore the limits of steady-state heating efficiency for conventional air-source heat pumps. The method used allows for the simultaneous optimization of ten selected design variables, taking proper account of their interactions, while constraining other parameters to chosen limits or fixed values. Designs were optimized for a fixed heating capacity, but the results may be scaled to other capacities. Substantial performance improvement is predicted compared to today's state of the art heat pump. With increased component efficiencies that are expected in the near future and with modest increases in heat exchanger area, a 28% increase in heating efficiency is predicted; for long-term improvements with considerably larger heat exchangers, a 56% increase is possible. The improved efficiencies are accompanied by substantial reductions in the requirements for compressor and motor size. The predicted performance improvements are attributed not only to improved components and larger heat exchangers but also to the use of an optimizing design procedure. Deviations from the optimized design may be necessary to make use of available component sizes and to maintain good cooling-mode performance while improving the heating efficiency. Sensitivity plots (i.e., COP as a function of one or more design parameters) were developed to explore design flexibilities and to evaluate their consequences. The performance of the optimized designs was compared to that of modified ideal cycles to assess the factors that limit further improvement. It is hoped that the design methods developed will be useful to designers in the heat pump industry.

  5. Wireless Condition Monitoring and Maintenance for Rooftop Packaged Heating, Ventilation, and Air-Conditioning

    SciTech Connect

    Katipamula, Srinivas; Brambley, Michael R.

    2004-06-01

    Rooftop package air-conditioning and heat pumps, while representing over half of U.S. commercial-building cooling energy consumption, are some of the most neglected of building systems. They are often found with inoperable dampers, dirty/clogged filters and coils, incorrect refrigerant charges, failing compressors, failed fans, missing enclosure panels, un-calibrated controls, failed sensors, and other problems. Frequently, actual operating hours deviate considerably from intended (and assumed) schedules. Although there are no reliable estimates on what fraction of the units operate under degraded conditions and the energy inefficiencies associated with such operations, a range of savings from 10 to 30% are generally believed to be achievable by enhancing operation of these units. Potential national energy savings from proper operation range from 23 to 70 trillion Btus annually in the U.S. Since the cost associated with conventional monitoring and servicing is quite high, conventional monitoring is seldom done. Combinations of wireless sensing and data acquisition, monitoring tools, automated diagnostics and prognostics show considerable promise to help remedy this maintenance problem for package HVAC units and the underserved small commercial building sector in which they are predominantly installed. This paper characterizes the current problem with maintenance of packaged air conditioners and heat pumps, provides estimates of the total energy impacts of the problem, and describes a generic system in which these developing technologies are used to provide real-time condition monitoring for package HVAC units and their components. Costs with today's technology are provided and future costs are estimated, showing that benefits will greatly exceed costs in many cases particularly if low-cost wireless monitoring is used.

  6. Side-specific effects by cadmium exposure: Apical and basolateral treatment in a coculture model of the blood-air barrier

    SciTech Connect

    Papritz, Mirko; Pohl, Christine; Wuebbeke, Christoph; Moisch, Michaela; Hofmann, Helene; Hermanns, Maria Iris; Thiermann, Horst; Kirkpatrick, Charles James; Kehe, Kai

    2010-06-15

    Cadmium (Cd{sup 2+}) is a widespread environmental pollutant, which is associated with a wide variety of cytotoxic and metabolic effects. Recent studies showed that intoxication with the heavy metal most importantly targets the integrity of the epithelial barrier. In our study, the lung epithelial cell line, NCI H441, was cultured with the endothelial cell line, ISO-HAS-1, as a bilayer on a 24-well HTS-Transwell (registered) filter plate. This coculture model was exposed to various concentrations of CdCl{sub 2}. The transepithelial electrical resistance decreased on the apical side only after treatment with high Cd{sup 2+} concentrations after 48 h. By contrast, a breakdown of TER to less than 5% of baseline could be observed much earlier (after 24 h) when Cd{sup 2+} was administered from the basal side. Observations of cell layer fragmentation and widening of intercellular spaces confirmed the barrier breakdown only for the basolaterally treated samples. Furthermore, the cytotoxicity and release of proinflammatory markers was enhanced if samples were exposed to Cd{sup 2+} from the basal side compared to treatment from the apical side. Moreover, we could demonstrate that a high concentration of Ca{sup 2+} could prevent the barrier-disrupting effect of Cd{sup 2+}. In conclusion, the exposure of Cd{sup 2+} to cocultures of lung cells caused a decrease in TER, major morphological changes, a reduction of cell viability and an increase of cytokine release, but the effects markedly differed between the two modes of exposure. Therefore, our results suggest that intact epithelial TJs may play a major role in protecting the air-blood barrier from inhaled Cd{sup 2+}.

  7. [Observation on the air-borne bacteria and ammonia (NS3) gas in laboratory animal facility with rotary heat exchanger].

    PubMed

    Obara, T; Matsuyama, M; Fujita, S; Yamauchi, C

    1979-01-01

    The number of air-borne bacteria in air ducts and barrierred laboratory animal rooms with the so-called econovent rotary heat exchanger, were checked monthly during a year by the pin-hole sumpler method for air ducts and Koch method for animal rooms. Also, concentration of ammonia was checked with the same samples by gas impinger. No significantly difference in number of air-borne bacteria was seen between before and after passing the econovent. Those passing through HEPA filter was not detected. There were more air-borne bacteria in animal rooms, outside locker room and shower room than in the corridor, utensil storage, inside locker room and pass box. No ammonia were detected in the outdoor, but exhaust air duct after passing the econovent contained very small amount of ammonia. On the other hand, high concentration of ammonia were preserved in the supplying air duct, exhaust air duct and mice and rats rooms, about 86% of ammonia in exhaust air duct returned back into the supplying air duct. No influences on reproduction in mice and rats were recognized.

  8. Increased Air Velocity Reduces Thermal and Cardiovascular Strain in Young and Older Males during Humid Exertional Heat Stress.

    PubMed

    Wright Beatty, Heather E; Hardcastle, Stephen G; Boulay, Pierre; Flouris, Andreas D; Kenny, Glen P

    2015-01-01

    Older adults have been reported to have a lower evaporative heat loss capacity than younger adults during exercise when full sweat evaporation is permitted. However, it is unclear how conditions of restricted evaporative and convective heat loss (i.e., high humidity, clothing insulation) alter heat stress. to the purpose of this study was to examine the heat stress responses of young and older males during and following exercise in a warm/humid environment under two different levels of air velocity. Ten young (YOUNG: 24±2 yr) and 10 older (OLDER: 59±3 yr) males, matched for body surface area performed 4×15-min cycling bouts (15-min rest) at a fixed rate of heat production (400 W) in warm/humid conditions (35°C, 60% relative humidity) under 0.5 (Low) and 3.0 (High) m·s(-1) air velocity while wearing work coveralls. Rectal (Tre) and mean skin (MTsk) temperatures, heart rate (HR), local sweat rate, % max skin blood flow (SkBF) (recovery only), and blood pressure (recovery only) were measured. High air velocity reduced core and skin temperatures (p < 0.05) equally in YOUNG and OLDER males (p > 0.05) but was more effective in reducing cardiovascular strain (absolute and % max HR; p < 0.05) in YOUNG males (p < 0.05). Greater increases in local dry heat loss responses (% max SkBF and cutaneous vascular conductance) were detected across time in OLDER than YOUNG males in both conditions (p < 0.05). Local dry heat loss responses and cardiovascular strain were attenuated during the High condition in YOUNG compared to OLDER (p < 0.05). High air velocity reduced the number of males surpassing the 38.0°C Tre threshold from 90% (Low) to 50% (High). Despite age-related local heat loss differences, YOUNG and OLDER males had similar levels of heat stress during intermittent exercise in warm and humid conditions while wearing work coveralls. Increased air velocity was effective in reducing heat stress equally, and cardiovascular strain to a greater extent, in YOUNG and OLDER

  9. Theoretical and Experimental Investigations of Cylindrical Air-Heating Solar Collector

    NASA Astrophysics Data System (ADS)

    Pelece, I.; Shipkovs, P.

    2016-06-01

    Solar energy is used not only at low latitudes, where it is available at large amounts, but also at higher latitudes, where height of sun and irradiance are significantly lower. On the other hand, the length of day at higher latitudes is longer in summer than at low latitudes, and also the path of the sun is longer. The present research deals with seeking for new shapes of solar collectors capable of receiving more solar energy. For designing and evaluating new shapes of solar collectors, it is necessary to have new methods for simple calculations of energy received from the sun by surface of any shape and direction. Such a method is explained in the present paper. Based on calculations by the proposed method, a new form of solar collector - a cylindrical collector - has been worked out. This collector is intended for air heating, but main principles can also be used for water heating, and even for photovoltaics. A cylindrical collector receives more energy in the morning and evening than a flat one, but at midday power of both collectors is equal, if effective areas are equal. Daily energy sum of the cylindrical solar collector is 1.5 times greater than that of the flat one.

  10. Modelica Library for Building Heating, Ventilation and Air-Conditioning Systems

    SciTech Connect

    Wetter, Michael

    2009-06-17

    This paper presents a freely available Modelica library for building heating, ventilation and air conditioning systems. The library is based on the Modelica.Fluid library. It has been developed to support research and development of integrated building energy and control systems. The primary applications are controls design, energy analysis and model-based operation. The library contains dynamic and steady-state component models that are applicable for analyzing fast transients when designing control algorithms and for conducting annual simulations when assessing energy performance. For most models, dimensional analysis is used to compute the performance for operating points that differ from nominal conditions. This allows parameterizing models in the absence of detailed geometrical information which is often impractical to obtain during the conceptual design phase of building systems. In the first part of this paper, the library architecture and the main classes are described. In the second part, an example is presented in which we implemented a model of a hydronic heating system with thermostatic radiator valves and thermal energy storage.

  11. Risk Assessment of Heating, Ventilating, and Air-Conditioning Strategies in Low-Load Homes

    SciTech Connect

    Poerschke, Andrew

    2016-02-17

    "Modern, energy efficient homes conforming to the Zero Energy Ready Home standard face the challenge of meeting high customer expectations for comfort. Traditional heating, ventilation, and air conditioning (HVAC) sizing and control strategies may be insufficient to adequately condition each zone due to unique load patterns in each room caused by a number of factors. These factors include solar heat gains, occupant-related gains, and gains associated with appliances and electronics. Because of shrinking shell loads, these intermittent factors are having an increasingly significant impact on the thermal load in each zone. Consequently, occupant comfort can be compromised. To evaluate the impact of climate and house geometry, as well as HVAC system and control strategies on comfort conditions, IBACOS analyzed the results of 99 TRNSYS multiple-zone simulations. The results of this analysis indicate that for simple-geometry and single-story plans, a single zone and thermostat can adequately condition the entire house. Demanding house geometry and houses with multiple stories require the consideration of multiple thermostats and multiple zones.

  12. Secondary effects of urban heat island mitigation measures on air quality

    NASA Astrophysics Data System (ADS)

    Fallmann, Joachim; Forkel, Renate; Emeis, Stefan

    2016-01-01

    This study presents numerical simulations analysing the effect of urban heat island (UHI) mitigation measures on the chemical composition of the urban atmosphere. The mesoscale chemical transport model WRF-Chem is used to investigate the impact of urban greening and highly reflective surfaces on the concentrations of primary (CO, NO) as well as secondary pollutants (O3) inside the urban canopy. In order to account for the sub-grid scale heterogeneity of urban areas, a multi-layer urban canopy model is coupled to WRF-Chem. Using this canopy model at its full extend requires the introduction of several urban land use classes in WRF-Chem. The urban area of Stuttgart serves as a test bed for the modelling of a case scenario of the 2003 European Heat Wave. The selected mitigation measures are able to reduce the urban temperature by about 1 K and the mean ozone concentration by 5-8%. Model results however document also negative secondary effects on urban air quality, which are closely related to a decrease of vertical mixing in the urban boundary layer. An increase of primary pollutants NO and CO by 5-25% can be observed. In addition, highly reflective surfaces can increase peak ozone concentration by up to 12% due to a high intensity of reflected shortwave radiation accelerating photochemical reactions.

  13. Novel mono-static arrangement of the ASDEX Upgrade high field side reflectometers compatible with electron cyclotron resonance heating stray radiationa)

    NASA Astrophysics Data System (ADS)

    Silva, A.; Varela, P.; Meneses, L.; Manso, M.; ASDEX Upgrade Team

    2012-10-01

    The ASDEX Upgrade frequency modulated continuous wave broadband reflectometer system uses a mono-static antenna configuration with in-vessel hog-horns and 3 dB directional couplers. The operation of the new electron cyclotron resonance heating (ECRH) launcher and the start of collective Thomson scattering experiments caused several events where the fragile dummy loads inside the high field side directional couplers were damaged, due to excessive power resulting from the ECRH stray fields. In this paper, we present a non-conventional application of the existing three-port directional coupler that hardens the system to the ECRH stray fields and at the same time generates the necessary reference signal. Electromagnetic simulations and laboratory tests were performed to validate the proposed solution and are compared with the in-vessel calibration tests.

  14. Novel mono-static arrangement of the ASDEX Upgrade high field side reflectometers compatible with electron cyclotron resonance heating stray radiation.

    PubMed

    Silva, A; Varela, P; Meneses, L; Manso, M

    2012-10-01

    The ASDEX Upgrade frequency modulated continuous wave broadband reflectometer system uses a mono-static antenna configuration with in-vessel hog-horns and 3 dB directional couplers. The operation of the new electron cyclotron resonance heating (ECRH) launcher and the start of collective Thomson scattering experiments caused several events where the fragile dummy loads inside the high field side directional couplers were damaged, due to excessive power resulting from the ECRH stray fields. In this paper, we present a non-conventional application of the existing three-port directional coupler that hardens the system to the ECRH stray fields and at the same time generates the necessary reference signal. Electromagnetic simulations and laboratory tests were performed to validate the proposed solution and are compared with the in-vessel calibration tests.

  15. Analyzing One-Sided vs. Two-Sided Subduction Arising from Mantle Convection Simulations

    NASA Astrophysics Data System (ADS)

    Kaplan, M. S.; Becker, T. W.

    2013-12-01

    Purely thermal plate tectonic generation models struggle to consistently reproduce one-sided subduction as is observed on Earth (Tackley 2000; Van Heck and Tackley 2008; Foley and Becker 2009), and instead produce two-sided subduction where the subducting slab contains a significant flux of material from both plates. The models of Crameri et al. (2012) demonstrate that the implementation of a free upper surface boundary condition and the inclusion of a weak hydrated crust can facilitate one-sided subduction. We employ a similar model configuration to Crameri et al. (2012) to further investigate the dynamics and energetics which are associated with one-sided vs. two-sided subduction. We use a 2D finite difference code based off of the algorithms of I2ELVIS (Gerya and Yuen 2007) where material parameters are tracked on Lagrangian markers and the Stokes and Energy equations are solved on a Cartesian grid. A free surface is implemented by a low viscosity and density 'sticky air layer' (Schmeling et al., 2008; Crameri et al., 2012) with the stabilization routine of Duretz et al. (2011) to prevent the 'drunken seaman' instability (Kaus et al., 2010). The effects of a weak crust, shear heating, a free surface or free slip upper mechanical boundary condition, plasticity as a function of depth or pressure, and the sticky air layer thermal conductivity on one-sided vs. two-sided subduction are investigated. When we observe one-sided subduction it is transient and can smoothly evolve back to a two-sided configuration. In our models, 'sidedness' is a spectrum, rather than either discretely one or two sided, and the models move between the two regimes throughout the model runs. We observe that the thermal conductivity of the sticky air layer can influence the dynamics of the convective domain. Elevated values of thermal conductivity compared to those of rock must be implemented in the sticky air layer in order to maintain a constant temperature at the surface of the convective

  16. Ignition of an organic water-coal fuel droplet floating in a heated-air flow

    NASA Astrophysics Data System (ADS)

    Valiullin, T. R.; Strizhak, P. A.; Shevyrev, S. A.; Bogomolov, A. R.

    2017-01-01

    Ignition of an organic water-coal fuel (CWSP) droplet floating in a heated-air flow has been studied experimentally. Rank B2 brown-coal particles with a size of 100 μm, used crankcase Total oil, water, and a plasticizer were used as the main CWSP components. A dedicated quartz-glass chamber has been designed with inlet and outlet elements made as truncated cones connected via a cylindrical ring. The cones were used to shape an oxidizer flow with a temperature of 500-830 K and a flow velocity of 0.5-5.0 m/s. A technique that uses a coordinate-positioning gear, a nichrome thread, and a cutter element has been developed for discharging CWSP droplets into the working zone of the chamber. Droplets with an initial size of 0.4 to 2.0 mm were used. Conditions have been determined for a droplet to float in the oxidizer flow long enough for the sustainable droplet burning to be initiated. Typical stages and integral ignition characteristics have been established. The integral parameters (ignition-delay times) of the examined processes have been compared to the results of experiments with CWSP droplets suspended on the junction of a quick-response thermocouple. It has been shown that floating fuel droplets ignite much quicker than the ones that sit still on the thermocouple due to rotation of an CWSP droplet in the oxidizer flow, more uniform heating of the droplet, and lack of heat drainage towards the droplet center. High-speed video recording of the peculiarities of floatation of a burning fuel droplet makes it possible to complement the existing models of water-coal fuel burning. The results can be used for a more substantiated modeling of furnace CWSP burning with the ANSYS, Fluent, and Sigma-Flow software packages.

  17. The Atlanta Urban Heat Island Mitigation and Air Quality Modeling Project: How High-Resoution Remote Sensing Data Can Improve Air Quality Models

    NASA Technical Reports Server (NTRS)

    Quattrochi, Dale A.; Estes, Maurice G., Jr.; Crosson, William L.; Khan, Maudood N.

    2006-01-01

    The Atlanta Urban Heat Island and Air Quality Project had its genesis in Project ATLANTA (ATlanta Land use Analysis: Temperature and Air quality) that began in 1996. Project ATLANTA examined how high-spatial resolution thermal remote sensing data could be used to derive better measurements of the Urban Heat Island effect over Atlanta. We have explored how these thermal remote sensing, as well as other imaged datasets, can be used to better characterize the urban landscape for improved air quality modeling over the Atlanta area. For the air quality modeling project, the National Land Cover Dataset and the local scale Landpro99 dataset at 30m spatial resolutions have been used to derive land use/land cover characteristics for input into the MM5 mesoscale meteorological model that is one of the foundations for the Community Multiscale Air Quality (CMAQ) model to assess how these data can improve output from CMAQ. Additionally, land use changes to 2030 have been predicted using a Spatial Growth Model (SGM). SGM simulates growth around a region using population, employment and travel demand forecasts. Air quality modeling simulations were conducted using both current and future land cover. Meteorological modeling simulations indicate a 0.5 C increase in daily maximum air temperatures by 2030. Air quality modeling simulations show substantial differences in relative contributions of individual atmospheric pollutant constituents as a result of land cover change. Enhanced boundary layer mixing over the city tends to offset the increase in ozone concentration expected due to higher surface temperatures as a result of urbanization.

  18. Species and velocity visualization of unseeded heated air and combusting hydrogen jets using laser and flashlamp sources

    NASA Technical Reports Server (NTRS)

    Diskin, Glenn S.; Lempert, Walter R.; Miles, Richard B.

    1990-01-01

    Three techniques for the visualization of species and/or velocity in unseeded H2/air flames and heated air jets are described and preliminary image data are presented. The techniques described are: (1) simultaneous ArF laser imaging of H2, O2, and Rayleigh cross-section weighted density in an H2, O2, and Rayleigh cross-section weighted density in an H2/air flame; (2) ultraviolet flashlamp imaging of O2, OH, and Rayleigh cross-section weighted density in an H2/air flame; and (3) Raman Excitation plus Laser Induced Electronic Fluorescence velocimetry in heater air flows, up to static temperatures of 700 K. Application of these techniques, individually or in combination, should provide useful insight into mixing and reacting flows containing H2, O2, N2 and reaction intermediates such as OH.

  19. Transpired Solar Collector at NREL's Waste Handling Facility Uses Solar Energy to Heat Ventilation Air (Fact Sheet)

    SciTech Connect

    Not Available

    2010-09-01

    The transpired solar collector was installed on NREL's Waste handling Facility (WHF) in 1990 to preheat ventilation air. The electrically heated WHF was an ideal candidate for the this technology - requiring a ventilation rate of 3,000 cubic feet per meter to maintain safe indoor conditions.

  20. Commercialization of air conditioning heat pump/water heater. Final technical report, Volume 1: Transmittal documents; Executive summary; Project summary

    SciTech Connect

    1996-01-30

    This is the final technical report on a commercialization project for an air conditioning heat pump water heater. The objective of the project was to produce a saleable system which would be economically competitive with natural gas and cost effective with regard to initial cost versus annual operating costs. The development and commercialization of the system is described.

  1. Articulated, Performance-Based Instruction Objectives Guide for Air Conditioning, Refrigeration, and Heating. Volume II (Second Year).

    ERIC Educational Resources Information Center

    Henderson, William Edward, Jr., Ed.

    This articulation guide contains 17 units of instruction for the second year of a two-year vocational program designed to prepare the high school graduate to install, maintain, and repair various types of residential and commercial heating, air conditioning, and refrigeration equipment. The units are designed to help the student to expand and…

  2. Multimedia Approach to Self-Paced Individualized Instruction in Air Conditioning, Refrigeration and Heating and Other Vocational Programs. Final Report.

    ERIC Educational Resources Information Center

    Oil Belt Vocational Technical School, El Dorado, AR.

    A multimedia, self-paced, individualized instructional program was designed to meet the needs of students in air conditioning, refrigeration, and heating programs at Oil Belt Vocational Technical School (Arkansas). The multimedia approach provided for video-based presentations to meet the needs for visual contact with the classroom and for…

  3. Ontology for Life-Cycle Modeling of Heating, Ventilating, and Air Conditioning (HVAC) Systems: Experimental Applications Using Revit

    DTIC Science & Technology

    2012-03-01

    Center, Construction Engineering Research Laboratory (ERDC-CERL) has developed a core life- cycle building information model ( BIM ) based on three...was to promote consistency and quality of content created for Building Information Models ( BIMs ) across various disciplines. The HVAC MVD was...MVD. 15. SUBJECT TERMS building information modeling ( BIM ), ontology, Army facilities, heating, ventilating, and air-conditioning (HVAC) systems

  4. Long-term variability of heat waves in Argentina and recurrence probability of the severe 2008 heat wave in Buenos Aires

    NASA Astrophysics Data System (ADS)

    Rusticucci, Matilde; Kyselý, Jan; Almeira, Gustavo; Lhotka, Ondřej

    2016-05-01

    Heat waves are one of the main concerns related to the impacts of climate change, because their frequency and severity are projected to increase in a future climate. The objectives of this work are to study the long-term variability of heat waves over Argentina and to estimate recurrence probability of the most severe 2008 heat wave in Buenos Aires. We used three definitions of heat waves that were based on (1) daily maximum temperature above the 90th percentile (MaxTHW), (2) daily minimum temperature above the 90th percentile (MinTHW) and (3) both maximum and minimum temperatures above the corresponding 90th percentiles (EHW). The minimum length of a heat wave was 3 days, and the analysis was performed over the October-March period. Decadal values in Buenos Aires experienced clear increases in heat waves according to MinTHW and EHW, with the highest frequency for both in the 2001-2010 decade, but at other stations, combinations of different trends and decadal variability resulted in some cases in a decrease of extreme heat waves. In the north-western part of the country, a strong positive change in the last decade was found, mainly due to the increment in the persistence of MinTHW but also accompanied by increases in MaxTHW. In general, other stations show a clear positive trend in MinTHW and decadal variability in MaxTHW, with the largest EHW cases in the last decade. We also estimated recurrence probability of the longest and most severe heat wave in Buenos Aires (over 1909-2010, according to intensity measured by the cumulative excess of maximum daily temperature above the 90th percentile) that occurred from 3 to 14 November 2008, by means of simulations with a stochastic first-order autoregressive model. The recurrence probability of such long and severe heat wave is small in the present climate but it is likely to increase substantially in the near future even under a moderate warming trend.

  5. Photoelectron reflection and scattering at Venus: an upper limit on the "polar wind" ambipolar electric field, and a new source of top-side ionospheric heating

    NASA Astrophysics Data System (ADS)

    Collinson, Glyn; Glocer, Alex; Grebowsky, Joe; Peterson, William; Frahm, Rudy; Moore, Thomas; Gilbert, Lin; Coates, Andrew

    2015-04-01

    An important mechanism in the generation of Earth's polar wind is the ambipolar potential generated by the outflow along open field lines of superthermal electrons. This ≈20V electric potential assists ions in overcoming the gravitational potential, and is a key mechanism for Terrestrial ionospheric escape. At Venus, except in rare circumstances, every field line is open, and a similar outflow of ionospheric electrons is observed. It is thus hypothesized that a similar electric potential may be present at Venus, contributing to global ionospheric loss. However, a very sensitive electric field instrument would be required to directly measure this potential, and no such instrument has yet been flown to Venus. In this pilot study, we examine photoelectron spectra measured by the ASPERA-ELS instrument on the Venus Express to put an initial upper bound on the total potential drop above 350km of Φ < 10V, weaker than at the Earth despite a comparable gravity field. We thus hypothesize that contrary to our current understanding, a "polar wind" like ambipolar electric field may not be as important a mechanism for atmospheric escape as previously suspected. Additionally, we find our spectra are consistent with the scattering of photoelectrons, the heating from which which we hypothesize may act as a source of top-side ionospheric heating, and may play a role in influencing the scale height of the ionosphere.

  6. Residential heating contribution to level of air pollutants (PAHs, major, trace, and rare earth elements): a moss bag case study.

    PubMed

    Vuković, Gordana; Aničić Urošević, Mira; Pergal, Miodrag; Janković, Milan; Goryainova, Zoya; Tomašević, Milica; Popović, Aleksandar

    2015-12-01

    In areas with moderate to continental climates, emissions from residential heating system lead to the winter air pollution peaks. The EU legislation requires only the monitoring of airborne concentrations of particulate matter, As, Cd, Hg, Ni, and B[a]P. Transition metals and rare earth elements (REEs) have also arisen questions about their detrimental health effects. In that sense, this study examined the level of extensive set of air pollutants: 16 polycyclic aromatic hydrocarbons (PAHs), and 41 major elements, trace elements, and REEs using Sphagnum girgensohnii moss bag technique. During the winter of 2013/2014, the moss bags were exposed across Belgrade (Serbia) to study the influence of residential heating system to the overall air quality. The study was set as an extension to our previous survey during the summer, i.e., non-heating season. Markedly higher concentrations of all PAHs, Sb, Cu, V, Ni, and Zn were observed in the exposed moss in comparison to the initial values. The patterns of the moss REE concentrations normalized to North American Shale Composite and Post-Archean Australian Shales were identical across the study area but enhanced by anthropogenic activities. The results clearly demonstrate the seasonal variations in the moss enrichment of the air pollutants. Moreover, the results point out a need for monitoring of air quality during the whole year, and also of various pollutants, not only those regulated by the EU Directive.

  7. Forced convective flow and heat transfer of upward cocurrent air-water slug flow in vertical plain and swirl tubes

    SciTech Connect

    Chang, Shyy Woei; Yang, Tsun Lirng

    2009-10-15

    This experimental study comparatively examined the two-phase flow structures, pressured drops and heat transfer performances for the cocurrent air-water slug flows in the vertical tubes with and without the spiky twisted tape insert. The two-phase flow structures in the plain and swirl tubes were imaged using the computerized high frame-rate videography with the Taylor bubble velocity measured. Superficial liquid Reynolds number (Re{sub L}) and air-to-water mass flow ratio (AW), which were respectively in the ranges of 4000-10000 and 0.003-0.02 were selected as the controlling parameters to specify the flow condition and derive the heat transfer correlations. Tube-wise averaged void fraction and Taylor bubble velocity were well correlated by the modified drift flux models for both plain and swirl tubes at the slug flow condition. A set of selected data obtained from the plain and swirl tubes was comparatively examined to highlight the impacts of the spiky twisted tape on the air-water interfacial structure and the pressure drop and heat transfer performances. Empirical heat transfer correlations that permitted the evaluation of individual and interdependent Re{sub L} and AW impacts on heat transfer in the developed flow regions of the plain and swirl tubes at the slug flow condition were derived. (author)

  8. Energy savings in one-pipe steam heating systems fitted with high-capacity air vents. Final report

    SciTech Connect

    Not Available

    1994-09-01

    Multifamily buildings heated by one-pipe steam systems experience significant temperature gradients from apartment to apartment, often reaching 15{degrees}F. As a result, many tenants are to cold, or if the heating system output is increased so as to heat the coldest apartment adequately, too hot. While both are undesirable, the second is particularly so because it wastes energy. It was thought that insufficient air venting of the steam pipes contributed to the gradient. Theoretically, if steam mains and risers are quickly vented, steam will reach each radiator at approximately the same time and balance apartment temperatures. The project`s objective was to determine if the installation of large-capacity air vents at the ends of steam mains and risers would economically reduce the temperature gradient between apartments and reduce the amount of space heating energy required. The test was conducted by enabling and disabling air vents biweekly in 10 multifamily buildings in New York City between December 1992 to May 1993. The temperatures of selected apartments and total space heating energy were compared during each venting regime. There was no difference in energy consumption between ``vents on`` and ``vents off`` periods (see Tables 2 and 5); however, there was a reduction in the maximum spread of apartment temperatures.

  9. A thermosyphon heat pipe cooler for high power LEDs cooling

    NASA Astrophysics Data System (ADS)

    Li, Ji; Tian, Wenkai; Lv, Lucang

    2016-08-01

    Light emitting diode (LED) cooling is facing the challenge of high heat flux more seriously with the increase of input power and diode density. The proposed unique thermosyphon heat pipe heat sink is particularly suitable for cooling of high power density LED chips and other electronics, which has a heat dissipation potential of up to 280 W within an area of 20 mm × 22 mm (>60 W/cm2) under natural air convection. Meanwhile, a thorough visualization investigation was carried out to explore the two phase flow characteristics in the proposed thermosyphon heat pipe. Implementing this novel thermosyphon heat pipe heat sink in the cooling of a commercial 100 W LED integrated chip, a very low apparent thermal resistance of 0.34 K/W was obtained under natural air convection with the aid of the enhanced boiling heat transfer at the evaporation side and the enhanced natural air convection at the condensation side.

  10. Comparison of forced-air warming and electric heating pad for maintenance of body temperature during total knee replacement.

    PubMed

    Ng, V; Lai, A; Ho, V

    2006-11-01

    We conducted a randomised controlled trial to compare the efficacy of forced-air warming (Bair Hugger(trade mark), Augustine Medical model 500/OR, Prairie, MN) with that of an electric heating pad (Operatherm 202, KanMed, Sweden) for maintenance of intra-operative body temperature in 60 patients undergoing total knee replacement under combined spinal-epidural anaesthesia. Intra-operative tympanic and rectal temperatures and verbal analogue score for thermal comfort were recorded. There were no differences in any measurements between the two groups, with mean (SD) final rectal temperatures of 36.8 (0.4) degrees C with forced-air warming and 36.9 (0.4) degrees C with the electric pad. The heating pad is as effective as forced-air warming for maintenance of intra-operative body temperature.

  11. Enhancement and performance evaluation for heat transfer of air cooling zone for reduction system of sponge titanium

    NASA Astrophysics Data System (ADS)

    Wang, Wenhao; Wu, Fuzhong; Jin, Huixin

    2017-02-01

    Since the magnesiothermic reduction employed in current sponge titanium is a highly exothermic reaction, the TiCl4 feed rate is carried out slowly to keep a suitable temperature in reduction reactor, which accounts for an extremely low level of productivity and energy efficiency. In order to shorten the production cycle and improve the energy efficiency, an enhancing scheme is proposed to enhance the heat transfer of air cooling zone for reduction system. The air cooling zone and enhancing scheme are firstly introduced. And then, the heat transfer characteristics of cooling zone are obtained by theoretical analysis and experimental date without enhancing scheme. Finally, the enhancement is analyzed and evaluated. The results show that the fitting results of heat transfer coefficients can be used to evaluate the heat transfer enhancement of cooling zone. Heat sources temperatures have a limited decreasing, heat transfer rate increases obviously with the enhanced cooling, and the TiCl4 feed rate can be increased significantly by 9.61 %. And the measured and calculated results are good enough to meet the design requirements.

  12. Enhancement and performance evaluation for heat transfer of air cooling zone for reduction system of sponge titanium

    NASA Astrophysics Data System (ADS)

    Wang, Wenhao; Wu, Fuzhong; Jin, Huixin

    2016-05-01

    Since the magnesiothermic reduction employed in current sponge titanium is a highly exothermic reaction, the TiCl4 feed rate is carried out slowly to keep a suitable temperature in reduction reactor, which accounts for an extremely low level of productivity and energy efficiency. In order to shorten the production cycle and improve the energy efficiency, an enhancing scheme is proposed to enhance the heat transfer of air cooling zone for reduction system. The air cooling zone and enhancing scheme are firstly introduced. And then, the heat transfer characteristics of cooling zone are obtained by theoretical analysis and experimental date without enhancing scheme. Finally, the enhancement is analyzed and evaluated. The results show that the fitting results of heat transfer coefficients can be used to evaluate the heat transfer enhancement of cooling zone. Heat sources temperatures have a limited decreasing, heat transfer rate increases obviously with the enhanced cooling, and the TiCl4 feed rate can be increased significantly by 9.61 %. And the measured and calculated results are good enough to meet the design requirements.

  13. Measured performance of the heat exchanger in the NASA icing research tunnel under severe icing and dry-air conditions

    NASA Technical Reports Server (NTRS)

    Olsen, W.; Vanfossen, J.; Nussle, R.

    1987-01-01

    Measurements were made of the pressure drop and thermal perfomance of the unique refrigeration heat exchanger in the NASA Lewis Icing Research Tunnel (IRT) under severe icing and frosting conditions and also with dry air. This data will be useful to those planning to use or extend the capability of the IRT and other icing facilities (e.g., the Altitude Wind Tunnel-AWT). The IRT heat exchanger and refrigeration system is able to cool air passing through the test section down to at least a total temperature of -30 C (well below icing requirements), and usually up to -2 C. The system maintains a uniform temperature across the test section at all airspeeds, which is more difficult and time consuming at low airspeeds, at high temperatures, and on hot, humid days when the cooling towers are less efficient. The very small surfaces of the heat exchanger prevent any icing cloud droplets from passing through it and going through the tests section again. The IRT heat exchanger was originally designed not to be adversely affected by severe icing. During a worst-case icing test the heat exchanger iced up enough so that the temperature uniformaity was no worse than about +/- 1 deg C. The conclusion is that the heat exchanger design performs well.

  14. High fidelity radiative heat transfer models for high-pressure laminar hydrogen-air diffusion flames

    NASA Astrophysics Data System (ADS)

    Cai, Jian; Lei, Shenghui; Dasgupta, Adhiraj; Modest, Michael F.; Haworth, Daniel C.

    2014-11-01

    Radiative heat transfer is studied numerically for high-pressure laminar H2-air jet diffusion flames, with pressure ranging from 1 to 30 bar. Water vapour is assumed to be the only radiatively participating species. Two different radiation models are employed, the first being the full spectrum k-distribution model together with conventional Radiative Transfer Equation (RTE) solvers. Narrowband k-distributions of water vapour are calculated and databased from the HITEMP 2010 database, which claims to retain accuracy up to 4000 K. The full-spectrum k-distributions are assembled from their narrowband counterparts to yield high accuracy with little additional computational cost. The RTE is solved using various spherical harmonics methods, such as P1, simplified P3 (SP3) and simplified P5 (SP5). The resulting partial differential equations as well as other transport equations in the laminar diffusion flames are discretized with the finite-volume method in OpenFOAM®. The second radiation model is a Photon Monte Carlo (PMC) method coupled with a line-by-line spectral model. The PMC absorption coefficient database is derived from the same spectroscopy database as the k-distribution methods. A time blending scheme is used to reduce PMC calculations at each time step. Differential diffusion effects, which are important in laminar hydrogen flames, are also included in the scalar transport equations. It was found that the optically thin approximation overpredicts radiative heat loss at elevated pressures. Peak flame temperature is less affected by radiation because of faster chemical reactions at high pressures. Significant cooling effects are observed at downstream locations. As pressure increases, the performance of RTE models starts to deviate due to increased optical thickness. SPN models perform only marginally better than P1 because P1 is adequate except at very high pressure.

  15. The heat source of the foehn revisited

    NASA Astrophysics Data System (ADS)

    Ólafsson, H.; Petersen, G. N.

    2012-04-01

    A large observational data set from Iceland is used to explore the connection between the heat surplus on the downstream side of mountains, upstream precipitation and elements of the atmospheric flow. A typical foehn case is also simulated and used to explore the role of precipitation and latent heat in heating the downstream flow. Some of the key findings are that latent heating appears not to be an important factor for heating the foehn in Iceland and that there is no clear relationship between upstream precipitation and downstream heating. The heating on the downstream side is attributed to descent of potentially warm air and insolation. The case study suggests that the latent heating may have an impact, however not through heating aloft, but through cooling at low levels and enhanced upstream blocking effect.

  16. Pyrolysis of polymeric materials. I - Effect of chemical structure, temperature, heating rate, and air flow on char yield and toxicity

    NASA Technical Reports Server (NTRS)

    Hilado, C. J.; Casey, C. J.

    1979-01-01

    Various polymeric materials, including synthetic polymers and cellulosic materials, were evaluated at different temperatures, heating rates and air flow rates for thermophysical and toxicological responses. It is shown that char yields appeared to be a function of air access as much as of the chemical structure of the material. It is stated that the sensitivity of the apparent thermal stability of some materials to air access is so marked that thermogravimetric studies in oxygen-free atmospheres may be a consistently misleading approach to comparing synthetic polymers intended to increase fire safety. Toxicity also appeared to be a function of temperature and air access as much as of the chemical structure of the material. Toxicity of the gases evolved seemed to increase with increasing char yield for some polymers.

  17. Heat transfer and friction factor correlations for a solar air heater duct roughened artificially with multiple v-ribs

    SciTech Connect

    Hans, V.S.; Saini, R.P.; Saini, J.S.

    2010-06-15

    The use of artificial roughness on the underside of the absorber plate is an effective and economic way to improve the thermal performance of a solar air heater. Several experimental investigations, involving different types of roughness elements, have been carried out to improve the heat transfer from the absorber plate to air flowing in solar air heaters. This paper presents an experimental investigation carried out to study the effect of multiple v-rib roughness on heat transfer coefficient and friction factor in an artificially roughened solar air heater duct. The experiment encompassed Reynolds number (Re) from 2000 to 20000, relative roughness height (e/D) values of 0.019-0.043, relative roughness pitch (P/e) range of 6-12, angle of attack ({alpha}) range of 30-75 and relative roughness width (W/w) range of 1-10. Extensive experimentation has been conducted to collect data on heat transfer and fluid flow characteristics of a rectangular duct roughened with multiple v-ribs. Using these experimental data, correlations for Nusselt number and friction factor in terms of roughness geometry and flow parameters have been developed. (author)

  18. Experimental Heat Transfer and Bulk Air Temperature Measurements for a Multipass Internal Cooling Model with Ribs and Bleed

    NASA Technical Reports Server (NTRS)

    Thurman, Douglas; Poinsatte, Philip

    2001-01-01

    An experimental study was made to obtain heat transfer and air temperature data for a simple three-leg serpentine test section that simulates a turbine blade internal cooling passage with trip strips and bleed holes. The objectives were to investigate the interaction of ribs and various bleed conditions on internal cooling and to gain a better understanding of bulk air temperature in an internal passage. Steady-state heat transfer measurements were obtained using a transient technique with thermochromic liquid crystals. Trip strips were attached to one wall of the test section and were located either between or near the bleed holes. The bleed holes, used for film cooling, were metered to simulate the effect of external pressure on the turbine blade. Heat transfer enhancement was found to be greater for ribs near bleed holes compared to ribs between holes, and both configurations were affected slightly by bleed rates upstream. Air temperature measurements were taken at discrete locations along one leg of the model. Average bulk air temperatures were found to remain fairly constant along one leg of the model.

  19. Experimental Heat Transfer and Bulk Air Temperature Measurements for a Multipass Internal Cooling Model with Ribs and Bleed

    NASA Technical Reports Server (NTRS)

    Thurman, Douglas; Poinsatte, Philip

    2000-01-01

    An experimental study was made to obtain heat transfer and air temperature data for a simple 3-leg serpentine test section that simulates a turbine blade internal cooling passage with trip strips and bleed holes. The objectives were to investigate the interaction of ribs and various bleed conditions on internal cooling and to gain a better understanding of bulk air temperature in an internal passage. Steady state heat transfer measurements were obtained using a transient technique with thermochromic liquid crystals. Trip strips were attached to one wall of the test section and were located either between or near the bleed holes. The bleed holes, used for film cooling, were metered to simulate the effect of external pressure on the turbine blade. Heat transfer enhancement was found to be greater for ribs near bleed holes compared to ribs between holes, and both configurations were affected slightly by bleed rates upstream. Air temperature measurements were taken at discreet locations along one leg of the model. Average bulk air temperatures were found to remain fairly constant along one leg of the model.

  20. Hybrid intelligent control scheme for air heating system using fuzzy logic and genetic algorithm

    SciTech Connect

    Thyagarajan, T.; Shanmugam, J.; Ponnavaikko, M.; Panda, R.C.

    2000-01-01

    Fuzzy logic provides a means for converting a linguistic control strategy, based on expert knowledge, into an automatic control strategy. Its performance depends on membership function and rule sets. In the traditional Fuzzy Logic Control (FLC) approach, the optimal membership is formed by trial-and-error method. In this paper, Genetic Algorithm (GA) is applied to generate the optimal membership function of FLC. The membership function thus obtained is utilized in the design of the Hybrid Intelligent Control (HIC) scheme. The investigation is carried out for an Air Heat System (AHS), an important component of drying process. The knowledge of the optimum PID controller designed, is used to develop the traditional FLC scheme. The computational difficulties in finding optimal membership function of traditional FLC is alleviated using GA In the design of HIC scheme. The qualitative performance indices are evaluated for the three control strategies, namely, PID, FLC and HIC. The comparison reveals that the HIC scheme designed based on the hybridization of FLC with GA performs better. Moreover, GA is found to be an effective tool for designing the FLC, eliminating the human interface required to generate the membership functions.

  1. Ultrafine particle removal by residential heating, ventilating, and air-conditioning filters.

    PubMed

    Stephens, B; Siegel, J A

    2013-12-01

    This work uses an in situ filter test method to measure the size-resolved removal efficiency of indoor-generated ultrafine particles (approximately 7-100 nm) for six new commercially available filters installed in a recirculating heating, ventilating, and air-conditioning (HVAC) system in an unoccupied test house. The fibrous HVAC filters were previously rated by the manufacturers according to ASHRAE Standard 52.2 and ranged from shallow (2.5 cm) fiberglass panel filters (MERV 4) to deep-bed (12.7 cm) electrostatically charged synthetic media filters (MERV 16). Measured removal efficiency ranged from 0 to 10% for most ultrafine particles (UFP) sizes with the lowest rated filters (MERV 4 and 6) to 60-80% for most UFP sizes with the highest rated filter (MERV 16). The deeper bed filters generally achieved higher removal efficiencies than the panel filters, while maintaining a low pressure drop and higher airflow rate in the operating HVAC system. Assuming constant efficiency, a modeling effort using these measured values for new filters and other inputs from real buildings shows that MERV 13-16 filters could reduce the indoor proportion of outdoor UFPs (in the absence of indoor sources) by as much as a factor of 2-3 in a typical single-family residence relative to the lowest efficiency filters, depending in part on particle size.

  2. Energy-Efficient Supermarket Heating, Ventilation, and Air Conditioning in Humid Climates in the United States

    SciTech Connect

    Clark, J.

    2015-03-01

    Supermarkets are energy-intensive buildings that consume the greatest amount of electricity per square foot of building of any building type in the United States and represent 5% of total U.S. commercial building primary energy use (EIA 2005). Refrigeration and heating, ventilation, and air-conditioning (HVAC) systems are responsible for a large proportion of supermarkets’ total energy use. These two systems sometimes work together and sometimes compete, but the performance of one system always affects the performance of the other. To better understand these challenges and opportunities, the Commercial Buildings team at the National Renewable Energy Laboratory investigated several of the most promising strategies for providing energy-efficient HVAC for supermarkets and quantified the resulting energy use and costs using detailed simulations. This research effort was conducted on behalf of the U.S. Department of Energy (DOE) Commercial Building Partnerships (CBP) (Baechler et al. 2012; Parrish et al. 2013; Antonopoulos et al. 2014; Hirsch et al. 2014). The goal of CBP was to reduce energy use in the commercial building sector by creating, testing, and validating design concepts on the pathway to net zero energy commercial buildings. Several CBP partners owned or operated buildings containing supermarkets and were interested in optimizing the energy efficiency of supermarket HVAC systems in hot-humid climates. These partners included Walmart, Target, Whole Foods Market, SUPERVALU, and the Defense Commissary Agency.

  3. Comparative study of denaturation of whey protein isolate (WPI) in convective air drying and isothermal heat treatment processes.

    PubMed

    Haque, M Amdadul; Aldred, Peter; Chen, Jie; Barrow, Colin J; Adhikari, Benu

    2013-11-15

    The extent and nature of denaturation of whey protein isolate (WPI) in convective air drying environments was measured and analysed using single droplet drying. A custom-built, single droplet drying instrument was used for this purpose. Single droplets having 5±0.1μl volume (initial droplet diameter 1.5±0.1mm) containing 10% (w/v) WPI were dried at air temperatures of 45, 65 and 80°C for 600s at constant air velocity of 0.5m/s. The extent and nature of denaturation of WPI in isothermal heat treatment processes was measured at 65 and 80°C for 600s and compared with those obtained from convective air drying. The extent of denaturation of WPI in a high hydrostatic pressure environment (600MPa for 600s) was also determined. The results showed that at the end of 600s of convective drying at 65°C the denaturation of WPI was 68.3%, while it was only 10.8% during isothermal heat treatment at the same medium temperature. When the medium temperature was maintained at 80°C, the denaturation loss of WPI was 90.0% and 68.7% during isothermal heat treatment and convective drying, respectively. The bovine serum albumin (BSA) fraction of WPI was found to be more stable in the convective drying conditions than β-lactoglobulin and α-lactalbumin, especially at longer drying times. The extent of denaturation of WPI in convective air drying (65 and 80°C) and isotheral heat treatment (80°C) for 600s was found to be higher than its denaturation in a high hydrostatic pressure environment at ambient temperature (600MPa for 600s).

  4. Benchmark performance analysis of an ECM-modulated air-to-air heat pump with a reciprocating compressor

    SciTech Connect

    Rice, C.K.

    1992-01-01

    A benchmark analysis was conducted to predict the maximum steady- state performance potential of a near-term modulating residential- size heat pump. Continuously variable-speed, permanent-magnet electronically commutated motors (ECMs) were assumed to modulate the compressor and the indoor and outdoor fans in conjunction with existing modulating reciprocating compressor technology. A modulating heat pump design tool was used to optimize this ECM benchmark heat pump, using speed ranges and total heat exchanger sizes per-unit-capacity equivalent to that used by the highest SEER-rated variable-speed unit presently on the market (SEER = 16.4). Parametric steady-state performance optimization was conducted at a nominal design cooling ambient of 95{degree}F (35{degree}C) and at three off-design ambients of 82{degree}F (27.8{degree}C) cooling and 47{degree}F and 17{degree}F (8.3{degree}C and {minus}8.3{degree}C) heating. In comparison to the reference commercially available residential unit, the analysis for the ECM benchmark predicted steady-state heating COPs about 35% higher and a cooling EER almost 25% higher at the nominal design cooling condition. The cooling EER at 82{degree}F (27. 8{degree}C) was 13% higher than that of the reference unit when a comparable sensible heat ratio of 0.71 was maintained, while an EER gain of 24% at the 82{degree}F (27.8{degree}C) rating point was predicted when the sensible heat ratio was relaxed to 0.83. 28 refs., 14 figs., 7 tabs.

  5. Simulation of solid oxide iron-air battery: Effects of heat and mass transfer on charge/discharge characteristics

    NASA Astrophysics Data System (ADS)

    Ohmori, Hiroko; Iwai, Hiroshi

    2015-07-01

    A time-dependent 2-D numerical simulation was performed on a solid oxide iron-air battery (SOIAB) to reveal the fundamental characteristics of this new system. The SOIAB is a rechargeable battery consisting of a solid oxide electrochemical cell (SOEC) and iron as a redox metal. A simple battery configuration was employed assuming a system with a small capacity. A simulation model for a unit element was developed considering heat and mass transfer in the system, taking both electrochemical and redox reactions into account. The numerical results showed the spatial and temporal changes in the temperature field in the charge and discharge operations, which were due to the combined effects of heat generation/absorption by the electrochemical and redox reactions and heat exchange with the air supplied through convective heat transfer. As the reaction rates are functions of the local temperature, the predicted results show the importance of considering the heat transfer phenomena in this system. It was also found that the active reaction region in the redox metal evolves with time. The nonuniform distribution of iron utilization is affected by the effective gas diffusion coefficients in the porous redox metal, and consequently the change in the current density distribution in the SOEC.

  6. CWS-Fired Residential Warm-Air Heating System. Quarterly report, February 1, 1988--April 30, 1988

    SciTech Connect

    Balsavich, J.; Becker, F.E.; Smolensky, L.A.

    1988-06-01

    During this quarter, work continued on testing and development of initial prototype components; it was found that the entire furnace system, including the combustor, peristaltic pump, Y-jet atomizer, and heat exchanger, performed reliably. The IRIS (Inertial Reactor with Internal Separation) achieved a carbon conversion efficiency of > 97%. Work also continued on fabrication and assembly of a second- generation, Proof-of-Concept system. This new unit incorporates a water-cooled combustor in please of the air-cooled one. Also, a heat exchanger with larger gas passages was built. 13 figs, 1 table.

  7. Correlation formulas for the frost thickness and heat transfer coefficient on a cylinder in humid air cross flow

    SciTech Connect

    Sengupta, S.; Sherif, S.A.; Wong, K.V.

    1995-12-31

    This paper reports on results of an experimental investigation where the emphasis was placed on obtaining empirical correlations for the frost thickness-time history and the heat transfer coefficient-time history for a cylinder in humid air cross flow. The facility employed for the investigation consisted of a low velocity wind tunnel comprised of a rectangular test section, a transition section and a honeycomb placed at the tunnel entrance. An external refrigerator was used to cool an antifreeze solution having a mixture of 90% methanol and 10% ethylene glycol. Measured parameters included, among other things, the heat transfer coefficient as well as the frost thickness.

  8. Effect of increasing urban albedo on meteorology and air quality of Montreal (Canada) - Episodic simulation of heat wave in 2005

    NASA Astrophysics Data System (ADS)

    Touchaei, Ali G.; Akbari, Hashem; Tessum, Christopher W.

    2016-05-01

    Increasing albedo is an effective strategy to mitigate urban air temperature in different climates. Using reflective urban surfaces decreases the air temperature, which potentially reduces the rate of generation of smog. However, for implementing the albedo enhancement, complicated interactions between air, moisture, aerosols, and other gaseous contaminant in the atmosphere should be considered. We used WRF-CHEM to investigate the effect of increasing albedo in Montreal, Canada, during a heat wave period (July 10th through July 12th, 2005) on air quality and urban climate. The reflectivity of roofs, walls, and roads are increased from 0.2 to 0.65, 0.6, and 0.45, respectively. Air temperature at 2-m elevation is decreased during all hours in the simulation period and the maximum reduction is about 1 °C on each day (Tmax is reduced by about 0.7 °C) The concentration of two regulated pollutants -ozone (O3) and fine particulate matters (PM2.5) - is calculated at a height of 5-m above the ground. The maximum decrease in 8-h averaged ozone concentration is about 3% (∼0.2 ppbv). 24-h averaged PM2.5 concentration decreases by 1.8 μg/m3. This relatively small change in concentration of pollutants is related to the decrease in planetary boundary layer height caused by increasing the albedo. Additionally, the combined effect of decreased solar heat gain by building surfaces and decreased air temperature reduces the energy consumption of HVAC systems by 2% (∼0.1 W/m2), which exacerbates the positive effect of the albedo enhancement on the air quality.

  9. Heating, Ventilating, and Air-Conditioning: Recent Advances in Diagnostics and Controls to Improve Air-Handling System Performance

    SciTech Connect

    Wray, Craig; Wray, Craig P.; Sherman, Max H.; Walker, I.S.; Dickerhoff, D.J.; Federspiel, C.C.

    2008-02-01

    The performance of air-handling systems in buildings needs to be improved. Many of the deficiencies result from myths and lore and a lack of understanding about the non-linear physical principles embedded in the associated technologies. By incorporating these principles, a few important efforts related to diagnostics and controls have already begun to solve some of the problems. This paper illustrates three novel solutions: one rapidly assesses duct leakage, the second configures ad hoc duct-static-pressure reset strategies, and the third identifies useful intermittent ventilation strategies. By highlighting these efforts, this paper seeks to stimulate new research and technology developments that could further improve air-handling systems.

  10. Exploiting zone trapping to avoid liberation of air bubbles in flow-based analytical procedures requiring heating.

    PubMed

    Vida, Ana C F; Zagatto, Elias A G

    2014-01-01

    In flow-based analytical procedures requiring heating, liberation of air bubbles is avoided by trapping a sample selected portion into a heated hermetic environment. The flow-through cuvette is maintained into a temperature-controlled aluminium block, thus acting as the trapping element and allowing real-time monitoring. The feasibility of the innovation was demonstrated in the spectrophotometric catalytic determination of vanadium in mineral waters. Air bubbles were not released even for temperatures as high as 95°C. The proposed system handles about 25 samples per hour, requires only 3 mg p-anisidine per determination and yields precise results (r.s.d. = 2.1%), in agreement with ICP-MS. Detection limit was evaluated (3.3 σ criterion) as 0.1 μg L(-1) V.

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

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

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

  12. Effectiveness of photocatalytic filter for removing volatile organic compounds in the heating, ventilation, and air conditioning system.

    PubMed

    Yu, Kuo-Pin; Lee, Grace Whei-May; Huang, Wei-Ming; Wu, Chih-Cheng; Lou, Chia-ling; Yang, Shinhao

    2006-05-01

    Nowadays, the heating, ventilation, and air conditioning (HVAC) system has been an important facility for maintaining indoor air quality. However, the primary function of typical HVAC systems is to control the temperature and humidity of the supply air. Most indoor air pollutants, such as volatile organic compounds (VOCs), cannot be removed by typical HVAC systems. Thus, some air handling units for removing VOCs should be added in typical HVAC systems. Among all of the air cleaning techniques used to remove indoor VOCs, photocatalytic oxidation is an attractive alternative technique for indoor air purification and deodorization. The objective of this research is to investigate the VOC removal efficiency of the photocatalytic filter in a HVAC system. Toluene and formaldehyde were chosen as the target pollutants. The experiments were conducted in a stainless steel chamber equipped with a simplified HVAC system. A mechanical filter coated with Degussa P25 titania photocatalyst and two commercial photocatalytic filters were used as the photocatalytic filters in this simplified HVAC system. The total air change rates were controlled at 0.5, 0.75, 1, 1.25, and 1.5 hr(-1), and the relative humidity (RH) was controlled at 30%, 50%, and 70%. The ultraviolet lamp used was a 4-W, ultraviolet-C (central wavelength at 254 nm) strip light bulb. The first-order decay constant of toluene and formaldehyde found in this study ranged from 0.381 to 1.01 hr(-1) under different total air change rates, from 0.34 to 0.433 hr(-1) under different RH, and from 0.381 to 0.433 hr(-1) for different photocatalytic filters.

  13. Commercialization of air conditioning heat pump/water heater. Final technical report, Volume 3: Appendix F through I

    SciTech Connect

    1996-01-30

    This is the final technical report on a commercialization project for an air conditioning heat pump water heater. The objective of the project was to produce a saleable system which would be economically competitive with natural gas and cost effective with regard to initial cost versus annual operating costs. The development and commercialization of the system is described. Compiled data included in numerous figures, tables and graphs.

  14. Evaluation of Technical and Utility Programmatic Challenges With Residential Forced-Air Integrated Space/Water Heat Systems

    SciTech Connect

    Kingston, Tim; Vadnal, Hillary; Scott, Shawn; Kalensky, Dave

    2016-12-01

    This multi-unit field demonstration of combined space and water heating (combi) systems was conducted to help document combi system installation and performance issues that needed to be addressed through research. The objective of the project was to put commercialized forced-air tankless combi units into the field through local contractors that were trained by manufacturers and GTI staff under the auspices of utility-implemented ETPs.

  15. Commercialization of air conditioning heat pump/water heater. Final technical report, Volume 2: Appendix A through E

    SciTech Connect

    1996-01-30

    This is the final technical report on a commercialization project for an air conditioning heat pump water heater. The objective of the project was to produce a saleable system which would be economically competitive with natural gas and cost effective with regard to initial cost versus annual operating costs. The development and commercialization of the system is described. Compiled data included in numerous figures, tables and graphs.

  16. An assessment of gas-side fouling in cement plants

    NASA Technical Reports Server (NTRS)

    Marner, W. J.

    1982-01-01

    The cement industry is the most energy-intensive industry in the United States in terms of energy cost as a percentage of the total product cost. An assessment of gas-side fouling in cement plants with special emphasis on heat recovery applications is provided. In the present context, fouling is defined as the buildup of scale on a heat-transfer surface which retards the transfer of heat and includes the related problems of erosion and corrosion. Exhaust gases in the cement industry which are suitable for heat recovery range in temperature from about 100 to 1300 K, are generally dusty, may be highly abrasive, and are often heavily laden with alkalies, sulfates, and chlorides. Particulates in the exhaust streams range in size from molecular to about 100 micrometers in diameter and come from both the raw feed as well as the ash in the coal which is the primary fuel used in the cement industry. The major types of heat-transfer equipment used in the cement industry include preheaters, gas-to-air heat exchangers, waste heat boilers, and clinker coolers. At the present time, the trend in this country is toward suspension preheater systems, in which the raw feed is heated by direct contact with the hot kiln exit gases, and away from waste heat boilers as the principal method of heat recovery. The most important gas-side fouling mechanisms in the cement industry are those due to particulate, chemical reaction, and corrosion fouling.

  17. Heat transfer to two-phase air/water mixtures flowing in small tubes with inlet disequilibrium

    NASA Technical Reports Server (NTRS)

    Janssen, J. M.; Florschuetz, L. W.; Fiszdon, J. P.

    1986-01-01

    The cooling of gas turbine components was the subject of considerable research. The problem is difficult because the available coolant, compressor bleed air, is itself quite hot and has relatively poor thermophysical properties for a coolant. Injecting liquid water to evaporatively cool the air prior to its contact with the hot components was proposed and studied, particularly as a method of cooling for contingency power applications. Injection of a small quantity of cold liquid water into a relatively hot coolant air stream such that evaporation of the liquid is still in process when the coolant contacts the hot component was studied. No approach was found whereby heat transfer characteristics could be confidently predicted for such a case based solely on prior studies. It was not clear whether disequilibrium between phases at the inlet to the hot component section would improve cooling relative to that obtained where equilibrium was established prior to contact with the hot surface.

  18. Numerical study of coupled transfer of heat and mass between air and water inside a geothermal water cooling tower

    NASA Astrophysics Data System (ADS)

    Bassem, Mohamed Mehdi; Bourouni, Karim; Thameur Chaibi, Mohamed

    2006-11-01

    In the south of Tunisia, geothermal water is used to irrigate cultures. Since its temperature is very high (70 C), geothermal water is cooled by cooling towers. These towers are sized empirically and present many operating problems such as excessive energy consumption, big loss of vapour and low cooling efficiency. The aim of our work is modelling the coupled heat and mass transfer between air and water inside the cooling tower. The most important results obtained are that the evaporative potential is dominating the convective one in the cooling process. That's why the cooling is more efficient in summer than in hibernal period when humidity of ambient air reaches high values. In other hand, the negative convective phenomenon is illustrated. In fact, at the bottom of the tower, water temperature reaches the air one; the two fluids begin to cooling simultaneously. Air is cooled by convection and water by evaporation. We demonstrate also that there is no point in putting fans in working during cold weather. We studied also the effect of the variation of heat transfer coefficient on the efficiency of cooling.

  19. Heat fluxes and roll circulations over the western Gulf Stream during an intense cold-air outbreak

    NASA Technical Reports Server (NTRS)

    Chou, Shu-Hsien; Ferguson, Michael P.

    1991-01-01

    Turbulence and heat fluxes in the marine atmospheric boundary layer (MABL) for three aircraft stacks near the western Gulf Stream front, observed during the Genesis of Atlantic Lows Experiment (GALE) January 28, 1986 cold-air outbreak, has been studied using mixed-layer scaling. The GOES image and stability parameter indicates that these three stacks were in the roll vortex regime. The turbulence structure in the MABL is studied for this case, as well as the significance of roll vortices to heat fluxes. The roll circulations are shown to contribute significantly to the sensible (temperature) and latent heat (moisture) fluxes with importance increasing upward. The results suggest that the entrainment at the MABL top might affect the the budgets of temperature and humidity fluxes in the lower MABL, but not in the unstable surface layer.

  20. ASME N511-19XX, Standard for periodic in-service testing of nuclear air treatment, heating, ventilating and air conditioning systems

    SciTech Connect

    1997-08-01

    A draft version of the Standard is presented in this document. The Standard covers the requirements for periodic in-service testing of nuclear safety-related air treatment, heating, ventilating, and air conditioning systems in nuclear facilities. The Standard provides a basis for the development of test programs and does not include acceptance criteria, except in cases where the results of one test influence the performance of other tests. The Standard covers general inspection and test requirements, reference values, inspection and test requirements, generic tests, acceptance criteria, in-service test requirements, testing following an abnormal incident, corrective action requirements, and quality assurance. Mandatory appendices provide a visual inspection checklist and four test procedures. Non-mandatory appendices provide additional information and guidance on mounting frame pressure leak test procedure, corrective action, challenge gas substitute selection criteria, and test program development. 8 refs., 10 tabs.

  1. Measure Guideline. Combination Forced-Air Space and Tankless Domestic Hot Water Heating Systems

    SciTech Connect

    Rudd, Armin

    2012-08-01

    This document describes design and application guidance for combination space and tankless domestic hot water heating systems (combination systems) used in residential buildings, based on field evaluation, testing, and industry meetings conducted by Building Science Corporation. As residential building enclosure improvements continue to drive heating loads down, using the same water heating equipment for both space heating and domestic water heating becomes attractive from an initial cost and space-saving perspective. This topic is applicable to single- and multi-family residential buildings, both new and retrofitted.

  2. Measure Guideline: Combination Forced-Air Space and Tankless Domestic Hot Water Heating Systems

    SciTech Connect

    Rudd, A.

    2012-08-01

    This document describes design and application guidance for combination space and tankless domestic hot water heating systems (combination systems) used in residential buildings, based on field evaluation, testing, and industry meetings conducted by Building Science Corporation. As residential building enclosure improvements continue to drive heating loads down, using the same water heating equipment for both space heating and domestic water heating becomes attractive from an initial cost and space-saving perspective. This topic is applicable to single- and multi-family residential buildings, both new and retrofitted.

  3. MULTI-SCALE MODELING AND APPROXIMATION ASSISTED OPTIMIZATION OF BARE TUBE HEAT EXCHANGERS

    SciTech Connect

    Bacellar, Daniel; Ling, Jiazhen; Aute, Vikrant; Radermacher, Reinhard; Abdelaziz, Omar

    2014-01-01

    Air-to-refrigerant heat exchangers are very common in air-conditioning, heat pump and refrigeration applications. In these heat exchangers, there is a great benefit in terms of size, weight, refrigerant charge and heat transfer coefficient, by moving from conventional channel sizes (~ 9mm) to smaller channel sizes (< 5mm). This work investigates new designs for air-to-refrigerant heat exchangers with tube outer diameter ranging from 0.5 to 2.0mm. The goal of this research is to develop and optimize the design of these heat exchangers and compare their performance with existing state of the art designs. The air-side performance of various tube bundle configurations are analyzed using a Parallel Parameterized CFD (PPCFD) technique. PPCFD allows for fast-parametric CFD analyses of various geometries with topology change. Approximation techniques drastically reduce the number of CFD evaluations required during optimization. Maximum Entropy Design method is used for sampling and Kriging method is used for metamodeling. Metamodels are developed for the air-side heat transfer coefficients and pressure drop as a function of tube-bundle dimensions and air velocity. The metamodels are then integrated with an air-to-refrigerant heat exchanger design code. This integration allows a multi-scale analysis of air-side performance heat exchangers including air-to-refrigerant heat transfer and phase change. Overall optimization is carried out using a multi-objective genetic algorithm. The optimal designs found can exhibit 50 percent size reduction, 75 percent decrease in air side pressure drop and doubled air heat transfer coefficients compared to a high performance compact micro channel heat exchanger with same capacity and flow rates.

  4. A neural network based optimization system provides on-line coal fired furnace air flow balancing for heat rate improvement and NO{sub x} reduction

    SciTech Connect

    Radl, B.J.; Roland, W. Jr.

    1995-12-31

    The optimization system provides on-line, real-time air flow balancing without extensive testing or large complex physical models. NO{sub x} emissions and unit heat rate are very sensitive to air distribution and turbulence in the combustion zone. These issues are continuously changing due to ambient conditions, coal quality and the condition of plant equipment. This report discusses applying on-line, real-time and neural network to adjust secondary air flow and overfire air flow to reduce NO{sub x} and improve heat rate on various coal fired boiler designs.

  5. [Heat and moisture exchangers for conditioning of inspired air of intubated patients in intensive care. The humidification properties of passive air exchangers under clinical conditions].

    PubMed

    Rathgeber, J; Züchner, K; Kietzmann, D; Weyland, W

    1995-04-01

    Heat and moisture exchangers (HME) are used as artificial noses for intubated patients to prevent tracheo-bronchial or pulmonary damage resulting from dry and cold inspired gases. HME are mounted directly on the tracheal tube, where they collect a large fraction of the heat and moisture of the expired air, adding this to the subsequent inspired breath. The effective performance depends on the water-retention capacity of the HME: the amount of water added to the inspired gas cannot exceed the stored water uptake of the previous breath. This study evaluates the efficiency of four different HME under laboratory and clinical conditions using a new moisture-measuring device. METHODS. In a first step, the absolute efficiency of four different HME (DAR Hygrobac, Gibeck Humid-Vent 2P, Pall BB 22-15 T, and Pall BB 100) was evaluated using a lung model simulating physiological heat and humidity conditions of the upper airways. The model was ventilated with tidal volumes of 500, 1,000, and 1,500 ml and different flow rates. The water content of the ventilated air was determined between tracheal tube and HME using a new high-resolution humidity meter and compared with the absolute water loss of the exhaled air at the gas outlet of a Siemens Servo C ventilator measured with a dew-point hygrometer. Secondly, the moisturizing efficiency was evaluated under clinical conditions in an intensive care unit with 25 intubated patients. Maintaining the ventilatory conditions for each patient, the HME were randomly changed. The humidity data were determined as described above and compared with the laboratory findings. RESULTS AND DISCUSSION. The water content at the respirator outlet is inversely equivalent to the humidity of the inspired gases and represents the water loss from the respiratory tract if the patient is ventilated with dry gases. Moisture retention and heating capacity decreased with higher volumes and higher flow rates. These data are simple to obtain without affecting the

  6. Heat pumps

    NASA Astrophysics Data System (ADS)

    Gilli, P. V.

    1982-11-01

    Heat pumps for residential/commercial space heating and hot tap water make use of free energy of direct or indirect solar heat and save from about 40 to about 70 percent of energy if compared to a conventional heating system with the same energy basis. In addition, the electrically driven compressor heat pump is able to substitute between 40% (bivalent alternative operation) to 100% (monovalent operation) of the fuel oil of an oilfired heating furnace. For average Central European conditions, solar space heating systems with high solar coverage factor show the following sequence of increasing cost effectiveness: pure solar systems (without heat pumps); heat pump assisted solar systems; solar assisted heat pump systems; subsoil/water heat pumps; air/water heat pumps; air/air heat pumps.

  7. Modeling of the anthropogenic heat flux and its effect on air quality over the Yangtze River Delta region, China

    NASA Astrophysics Data System (ADS)

    Xie, M.; Liao, J.; Wang, T.; Zhu, K.; Zhuang, B.; Han, Y.; Li, M.; Li, S.

    2015-11-01

    Anthropogenic heat (AH) emissions from human activities caused by urbanization can affect the city environment. Based on the energy consumption and the gridded demographic data, the spatial distribution of AH emission over the Yangtze River Delta (YRD) region is estimated. Meanwhile, a new method for the AH parameterization is developed in the WRF/Chem model, which incorporates the gridded AH emission data with the seasonal and the diurnal variations into the simulations. By running this upgraded WRF/Chem for two typical months in 2010, the impacts of AH on the meteorology and air quality over the YRD region are studied. The results show that the AH fluxes over YRD have been growing in recent decades. In 2010, the annual mean values of AH over Shanghai, Jiangsu and Zhejiang are 14.46, 2.61 and 1.63 W m-2 respectively, with the high values of 113.5 W m-2 occurring in the urban areas of Shanghai. These AH emissions can significantly change the urban heat island and urban-breeze circulations in the cities of the YRD region. In Shanghai, 2 m air temperature increases by 1.6 °C in January and 1.4 °C in July, the planetary boundary layer height rises up by 140 m in January and 160 m in July, and 10 m wind speed is enhanced by 0.7 m s-1 in January and 0.5 m s-1 in July, with higher increment at night. And the enhanced vertical movement can transport more moisture to higher levels, which causes the decrease of water vapor at the ground level and the increase in the upper PBL, and thereby induces the accumulative precipitation to increase by 15-30 % over the megacities in July. The adding AH can impact the spatial and vertical distributions of the simulated pollutants as well. The concentrations of primary air pollutants decrease near surface and increase at the upper levels, due mainly to the increases of PBLH, surface wind speed and upward air vertical movement. But surface O3 concentrations increase in the urban areas, with maximum changes of 2.5 ppb in January and 4

  8. STAR Measurements and Modeling for Quantifying Air Quality and Climatic Impacts of Residential Biomass or Coal Combustion for Cooking, Heating and Lighting Kick-off Meeting

    EPA Pesticide Factsheets

    STAR grantees and EPA scientists will discuss progress on their projects which aim to quantify the extent to which interventions for cleaner cooking, heating, or lighting can impact air quality and climate, which in turn affect human health and welfare

  9. High efficiency air cycle air conditioning system

    SciTech Connect

    Rannenberg, G. C.

    1985-11-19

    An air cycle air conditioning system is provided with regenerative heat exchangers upstream and downstream of an expansion turbine. A closedloop liquid circulatory system serially connects the two regenerative heat exchangers for regeneration without the bulk associated with air-to-air heat exchange. The liquid circulatory system may also provide heat transport to a remote sink heat exchanger and from a remote load as well as heat exchange within the sink heat exchanger and load for enhanced compactness and efficiency.

  10. Air flow resistance of three heat and moisture exchanging filter designs under wet conditions: implications for patient safety.

    PubMed

    Morgan-Hughes, N J; Mills, G H; Northwood, D

    2001-08-01

    Heat and moisture exchanging filters (HMEFs) can be blocked by secretions. We have studied HMEF performance under wet conditions to see which particular design features predispose to this complication. Dar Hygrobac-S (composite felt filter and cellulose exchanger), Dar Hygroster (composite pleated ceramic membrane and cellulose exchanger) and Pall BB22-15 (pleated ceramic membrane) HMEFs were tested. Saline retention, saline concealment, and changes in air flow resistance when wet were assessed. The cellulose exchanger in the composite Hygrobac-S and Hygroster retained saline, producing a 'tampon' effect, associated with bi-directional air flow resistances in excess of the international standard of a 5 cm H(2)O pressure drop at 60 litre min(-1) air flow. Furthermore, high air flow resistances occurred before free saline was apparent within the transparent filter housing. The pleat only BB22-15 showed a significant increase in expiratory air flow resistance, but only after the presence of saline was apparent. These data imply that composite HMEFs with cellulose exchangers are more likely to block or cause excessive work of breathing as a result of occult accumulation of patient secretions than pleat only HMEFs.

  11. Heat transfer measurements on biconics at incidence in hypersonic high enthalpy air and nitrogen flows

    NASA Technical Reports Server (NTRS)

    Gai, S. L.; Cain, T.; Joe, W. S.; Sandeman, R. J.; Miller, C. G.

    1988-01-01

    Heat transfer rate measurements have been obtained at 0, 5, 15, and 21 deg angles-of-attack for a straight biconic scale model of an aeroassisted orbital vehicle proposed for planetary probe missions. Heat-transfer distributions were measured using palladium thin-film resistance gauges deposited on a glass-ceramic substrate. The windward heat transfer correlations were based on equilibrium flow in the shock layer of the model, although the flow may depart from equilibrium in the flow-field.

  12. Measurements of average heat-transfer and friction coefficients for subsonic flow of air in smooth tubes at high surface and fluid temperatures

    NASA Technical Reports Server (NTRS)

    Humble, Leroy V; Lowdermilk, Warren H; Desmon, Leland G

    1951-01-01

    An investigation of forced-convection heat transfer and associated pressure drops was conducted with air flowing through smooth tubes for an over-all range of surface temperature from 535 degrees to 3050 degrees r, inlet-air temperature from 535 degrees to 1500 degrees r, Reynolds number up to 500,000, exit Mach number up to 1, heat flux up to 150,000 btu per hour per square foot, length-diameter ratio from 30 to 120, and three entrance configurations. Most of the data are for heat addition to the air; a few results are included for cooling of the air. The over-all range of surface-to-air temperature ratio was from 0.46 to 3.5.

  13. Local distribution of wall static pressure and heat transfer on a smooth flat plate impinged by a slot air jet

    NASA Astrophysics Data System (ADS)

    M, Adimurthy; Katti, Vadiraj V.

    2017-02-01

    Local distribution of wall static pressure and heat transfer on a smooth flat plate impinged by a normal slot air jet is experimental investigated. Present study focuses on the influence of jet-to-plate spacing ( Z/D h ) (0.5-10) and Reynolds number (2500-20,000) on the fluid flow and heat transfer distribution. A single slot jet with an aspect ratio ( l/b) of about 22 is chosen for the current study. Infrared Thermal Imaging technique is used to capture the temperature data on the target surface. Local heat transfer coefficients are estimated from the thermal images using `SMART VIEW' software. Wall static pressure measurement is carried out for the specified range of Re and Z/D h . Wall static pressure coefficients are seen to be independent of Re in the range between 5000 and 15,000 for a given Z/D h . Nu values are higher at the stagnation point for all Z/D h and Re investigated. For lower Z/D h and higher Re, secondary peaks are observed in the heat transfer distributions. This may be attributed to fluid translating from laminar to turbulent flow on the target plate. Heat transfer characteristics are explained based on the simplified flow assumptions and the pressure data obtained using Differential pressure transducer and static pressure probe. Semi-empirical correlation for the Nusselt number in the stagnation region is proposed.

  14. Local distribution of wall static pressure and heat transfer on a smooth flat plate impinged by a slot air jet

    NASA Astrophysics Data System (ADS)

    Adimurthy, M.; Katti, Vadiraj V.

    2016-06-01

    Local distribution of wall static pressure and heat transfer on a smooth flat plate impinged by a normal slot air jet is experimental investigated. Present study focuses on the influence of jet-to-plate spacing (Z/D h ) (0.5-10) and Reynolds number (2500-20,000) on the fluid flow and heat transfer distribution. A single slot jet with an aspect ratio (l/b) of about 22 is chosen for the current study. Infrared Thermal Imaging technique is used to capture the temperature data on the target surface. Local heat transfer coefficients are estimated from the thermal images using `SMART VIEW' software. Wall static pressure measurement is carried out for the specified range of Re and Z/D h . Wall static pressure coefficients are seen to be independent of Re in the range between 5000 and 15,000 for a given Z/D h . Nu values are higher at the stagnation point for all Z/D h and Re investigated. For lower Z/D h and higher Re, secondary peaks are observed in the heat transfer distributions. This may be attributed to fluid translating from laminar to turbulent flow on the target plate. Heat transfer characteristics are explained based on the simplified flow assumptions and the pressure data obtained using Differential pressure transducer and static pressure probe. Semi-empirical correlation for the Nusselt number in the stagnation region is proposed.

  15. International Space Station Common Cabin Air Assembly Condensing Heat Exchanger Hydrophilic Coating Operation, Recovery, and Lessons Learned

    NASA Technical Reports Server (NTRS)

    Balistreri, Steven F.; Steele, John W.; Caron, Mark E.; Laliberte, Yvon J.; Shaw, Laura A.

    2013-01-01

    The ability to control the temperature and humidity of an environment or habitat is critical for human survival. These factors are important to maintaining human health and comfort, as well as maintaining mechanical and electrical equipment in good working order to support the human and to accomplish mission objectives. The temperature and humidity of the International Space Station (ISS) United States On-orbit Segment (USOS) cabin air is controlled by the Common Cabin Air Assembly (CCAA). The CCAA consists of a fan, a condensing heat exchanger (CHX), an air/water separator, temperature and liquid sensors, and electrical controlling hardware and software. The CHX is the primary component responsible for control of temperature and humidity. The CCAA CHX contains a chemical coating that was developed to be hydrophilic and thus attract water from the humid influent air. This attraction forms the basis for water removal and therefore cabin humidity control. However, there have been several instances of CHX coatings becoming hydrophobic and repelling water. When this behavior is observed in an operational CHX in the ISS segments, the unit s ability to remove moisture from the air is compromised and the result is liquid water carryover into downstream ducting and systems. This water carryover can have detrimental effects on the ISS cabin atmosphere quality and on the health of downstream hardware. If the water carryover is severe and widespread, this behavior can result in an inability to maintain humidity levels in the USOS. This paper will describe the operation of the five CCAAs within the USOS, the potential causes of the hydrophobic condition, and the impacts of the resulting water carryover to downstream systems. It will describe the history of this behavior and the actual observed impacts to the ISS USOS. Information on mitigation steps to protect the health of future CHX hydrophilic coatings as well as remediation and recovery of the full heat exchanger will be

  16. A Simple Experiment To Measure the Content of Oxygen in the Air Using Heated Steel Wool

    ERIC Educational Resources Information Center

    Vera, Francisco; Rivera, Rodrigo; Nunez, Cesar

    2011-01-01

    The typical experiment to measure the oxygen content in the atmosphere uses the rusting of steel wool inside a closed volume of air. Two key aspects of this experiment that make possible a successful measurement of the content of oxygen in the air are the use of a closed atmosphere and the use of a chemical reaction that involves the oxidation of…

  17. Efficiency of Energy Use in the United States: Transportation, space heating, and air conditioning provide opportunities for large energy savings.

    PubMed

    Hirst, E; Moyers, J C

    1973-03-30

    We described three uses of energy for which greater efficiency is feasible: transportation, space heating, and air conditioning. Shifts to less energy-intensive transportation modes could substantially reduce energy consumption; the magnitude of such savings would, of course, depend on the extent of such shifts and possible load factor changes. The hypothetical transportation scenario described here results in a 22 percent savings in energy for transportation in 1970, a savings of 2800 trillion Btu. To the homeowner, increasing the amount of building insulation and, in some cases, adding storm windows would reduce energy consumption and provide monetary savings. If all homes in 1970 had the "economic optimum" amount of insulation, energy consumption for residential heating would have been 42 percent less than if the homes were insulated to meet the pre-1971 FHA standards, a savings of 3100 trillion Btu. Increased utilization of energy-efficient air conditioners and of building insulation would provide significant energy savings and help to reduce peak power demands during the summer. A 67 percent increase in energy efficiency for room air conditioners would have saved 15.8 billion kilowatt-hours in 1970. In conclusion, it is possible-from an engineering point of view-to effect considerable energy savings in the United States. Increases in the efficiency of energy use would provide desired end results with smaller energy inputs. Such measures will not reduce the level of energy consumption, but they could slow energy growth rates.

  18. Heat transfer performance comparison of steam and air in gas turbine cooling channels with different rib angles

    NASA Astrophysics Data System (ADS)

    Shi, Xiaojun; Gao, Jianmin; Xu, Liang; Li, Fajin

    2013-11-01

    Using steam as working fluid to replace compressed air is a promising cooling technology for internal cooling passages of blades and vanes. The local heat transfer characteristics and the thermal performance of steam flow in wide aspect ratio channels ( W/ H = 2) with different angled ribs on two opposite walls have been experimentally investigated in this paper. The averaged Nusselt number ratios and the friction factor ratios of steam and air in four ribbed channels were also measured under the same test conditions for comparison. The Reynolds number range is 6,000-70,000. The rib angles are 90°, 60°, 45°, and 30°, respectively. The rib height to hydraulic diameter ratio is 0.047. The pitch-to-rib height ratio is 10. The results show that the Nusselt number ratios of steam are 1.19-1.32 times greater than those of air over the range of Reynolds numbers studied. For wide aspect ratio channels using steam as the coolant, the 60° angled ribs has the best heat transfer performance and is recommended for cooling design.

  19. Influence of road traffic, residential heating and meteorological conditions on PM10 concentrations during air pollution critical episodes.

    PubMed

    Gualtieri, Giovanni; Toscano, Piero; Crisci, Alfonso; Di Lonardo, Sara; Tartaglia, Mario; Vagnoli, Carolina; Zaldei, Alessandro; Gioli, Beniamino

    2015-12-01

    The importance of road traffic, residential heating and meteorological conditions as major drivers of urban PM10 concentrations during air pollution critical episodes has been assessed in the city of Florence (Italy) during the winter season. The most significant meteorological variables (wind speed and atmospheric stability) explained 80.5-85.5% of PM10 concentrations variance, while a marginal role was played by major emission sources such as residential heating (12.1%) and road traffic (5.7%). The persistence of low wind speeds and unstable atmospheric conditions was the leading factor controlling PM10 during critical episodes. A specific PM10 critical episode was analysed, following a snowstorm that caused a "natural" scenario of 2-day dramatic road traffic abatement (-43%), and a massive (up to +48%) and persistent (8 consecutive days) increase in residential heating use. Even with such a strong variability in local PM10 emissions, the role of meteorological conditions was prominent, revealing that short-term traffic restrictions are insufficient countermeasures to reduce the health impacts and risks of PM10 critical episodes, while efforts should be made to anticipate those measures by linking them with air quality and weather forecasts.

  20. Analysis of an open-air swimming pool solar heating system by using an experimentally validated TRNSYS model

    SciTech Connect

    Ruiz, Elisa; Martinez, Pedro J.

    2010-01-15

    In the case of private outdoor swimming pools, seldom larger than 100 m{sup 2}, conventional auxiliary heating systems are being installed less and less. Solar heating is an option to extend the swimming season. The temperature evolution of an open-air swimming pool highly depends on the wind speed directly on the water surface, which at the same time is influenced by the surroundings of the pool. In this paper, the TRNSYS model of a private open-air pool with a 50-m{sup 2} surface was validated by registering the water temperature evolution and the meteorological data at the pool site. Evaporation is the main component of energy loss in swimming pools. Six different sets of constants found in literature were considered to evaluate the evaporative heat transfer coefficient with the purpose of finding the most suitable one for the TRNSYS pool model. In order to do that, the evolution of the pool water temperature predicted by the TRNSYS pool model was compared with the experimentally registered one. The simulation with TRNSYS of the total system, including the swimming pool and the absorber circuit integrated into the existing filter circuit, provided information regarding the increase of the pool temperature for different collector areas during the swimming season. This knowledge, together with the economic costs, support the decision about the absorber field size. (author)

  1. Investigation of the impact of extreme air temperature on river water temperature: case study of the heat episode 2013.

    NASA Astrophysics Data System (ADS)

    Weihs, Philipp; Trimmel, Heidelinde; Goler, Robert; Formayer, Herbert; Holzapfel, Gerda; Rauch, Hans Peter

    2014-05-01

    Water stream temperature is a relevant factor for water quality since it is an important driver of water oxygen content and in turn also reduces or increases stress on the aquatic fauna. The water temperature of streams is determined by the source and inflow water temperature, by the energy balance at the stream surface and by the hydrological regime of the stream. Main factors driving the energy balance of streams are radiation balance and air temperature which influences the sensitive and latent heat flux. The present study investigates the impact of the heat episode of summer 2013 on water temperature of two lowland rivers in south eastern Austria. Within the scope of the project BIO_CLIC routine measurements of water temperature at 33 locations alongside the rivers Pinka and Lafnitz have been performed since spring 2012. In addition meteorological measurements of global shortwave and longwave radiation, air temperature, wind and air humidity have been carried out during this time. For the same time period, data of discharge and water levels of both rivers were provided by the public hydrological office. The heat episode of summer 2013 started, according to the Kysely- definition, on 18 July and lasted until 14 August. The highest air temperature ever recorded in Austria was reported on 8 August at 40.5°C. In Güssing, which is located within the project area, 40.0 °C were recorded. In the lower reaches of the river Pinka, at the station Burg the monthly mean water temperature of August 2013 was with more than 22°C, 1°C higher than the mean water temperature of the same period of the previous years. At the same station, the maximum water temperature of 27.1°C was recorded on 29 July, 9 days prior to the air temperature record. Analysis shows that at the downstream stations the main driving parameter is solar radiation whereas at the upstream stations a better correlation between air temperature and water temperature is obtained. Using the extensive data set

  2. RESULTS OF A PILOT FIELD STUDY TO EVALUATE THE EFFECTIVENESS OF CLEANING RESIDENTIAL HEATING AND AIR-CONDITIONING SYSTEMS AND THE IMPACT ON INDOOR AIR QUALITY AND SYSTEM PERFORMANCE

    EPA Science Inventory

    The report discusses and gives results of a pilot field study to evaluate the effectiveness of air duct cleaning (ADC) as a source removal technique in residential heating and air-conditioning (HAC) systems and its impact on airborne particle, fiber, and bioaerosol concentrations...

  3. Cultural and Technical Evaluation of Heating Alternatives to Improve Indoor Air Quality on the Navajo Nation

    EPA Science Inventory

    In the Navajo Nation it is estimated that 62% of households use wood as their primary means of heating1. A 2010 study by the U.S. Geological Survey (USGS) and Diné College found that in Shiprock, NM, the largest town in the Navajo Nation (pop. = 8,300)2, heating is often w...

  4. 10 CFR Appendix M to Subpart B of... - Uniform Test Method for Measuring the Energy Consumption of Central Air Conditioners and Heat Pumps

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... testing with the following installed: (1) the most restrictive filter(s); (2) supplementary heating coils... ducted unit without having an indoor air filter installed is permissible as long as the minimum external... on region IV.) For heat pumps that use a time-adaptive defrost control system (see Definition...

  5. 10 CFR Appendix M to Subpart B of... - Uniform Test Method for Measuring the Energy Consumption of Central Air Conditioners and Heat Pumps

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... testing with the following installed: (1) the most restrictive filter(s); (2) supplementary heating coils... ducted unit without having an indoor air filter installed is permissible as long as the minimum external... on region IV.) For heat pumps that use a time-adaptive defrost control system (see Definition...

  6. 10 CFR Appendix M to Subpart B of... - Uniform Test Method for Measuring the Energy Consumption of Central Air Conditioners and Heat Pumps

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... testing with the following installed: (1) the most restrictive filter(s); (2) supplementary heating coils... ducted unit without having an indoor air filter installed is permissible as long as the minimum external... on region IV.) For heat pumps that use a time-adaptive defrost control system (see Definition...

  7. Changes in regional meteorology induced by anthropogenic heat and their impacts on air quality in South China

    NASA Astrophysics Data System (ADS)

    Xie, Min; Zhu, Kuanguang; Wang, Tijian; Feng, Wen; Gao, Da; Li, Mengmeng; Li, Shu; Zhuang, Bingliang; Han, Yong; Chen, Pulong; Liao, Jingbiao

    2016-12-01

    Anthropogenic heat (AH) emissions from human activities can change the urban circulation and thereby affect the air pollution in and around cities. Based on statistic data, the spatial distribution of AH flux in South China is estimated. With the aid of the Weather Research and Forecasting model coupled with Chemistry (WRF/Chem), in which the AH parameterization is developed to incorporate the gridded AH emissions with temporal variation, simulations for January and July in 2014 are performed over South China. By analyzing the differences between the simulations with and without adding AH, the impact of AH on regional meteorology and air quality is quantified. The results show that the regional annual mean AH fluxes over South China are only 0.87 W m-2, but the values for the urban areas of the Pearl River Delta (PRD) region can be close to 60 W m-2. These AH emissions can significantly change the urban heat island and urban-breeze circulations in big cities. In the PRD city cluster, 2 m air temperature rises by 1.1° in January and over 0.5° in July, the planetary boundary layer height (PBLH) increases by 120 m in January and 90 m in July, 10 m wind speed is intensified to over 0.35 m s-1 in January and 0.3 m s-1 in July, and accumulative precipitation is enhanced by 20-40 % in July. These changes in meteorological conditions can significantly impact the spatial and vertical distributions of air pollutants. Due to the increases in PBLH, surface wind speed and upward vertical movement, the concentrations of primary air pollutants decrease near the surface and increase in the upper levels. But the vertical changes in O3 concentrations show the different patterns in different seasons. The surface O3 concentrations in big cities increase with maximum values of over 2.5 ppb in January, while O3 is reduced at the lower layers and increases at the upper layers above some megacities in July. This phenomenon can be attributed to the fact that chemical effects can play a

  8. Solar heat pump simulator

    NASA Astrophysics Data System (ADS)

    Catan, M. A.

    A simulator was utilized to provide controlled-temperature sources and sinks to an experimental water-to-water laboratory heat pump test bed. This combination was used to demonstrate and explore the potential of the vapor-compression cycle to deliver high COP's at SAHP source temperatures. Results from the simulator were used in computer simulations of complete systems performed by BNL, by the SAHP contractors, and by others. A two-speed compressor was first tested at high source temperatures on the BNL simulator. In view of the decision by both contractors to construct water-to-air (rather than water-to-water) heat pumps, the BNL simulator was fitted with an air-side test loop. The prototype heat pump was tested under steady-state conditions on the BNL simulator.

  9. Heat transfer technology for internal passages of air-cooled blades for heavy-duty gas turbines.

    PubMed

    Weigand, B; Semmler, K; von Wolfersdorf, J

    2001-05-01

    The present review paper, although far from being complete, aims to give an overview about the present state of the art in the field of heat transfer technology for internal cooling of gas turbine blades. After showing some typical modern cooled blades, the different methods to enhance heat transfer in the internal passages of air-cooled blades are discussed. The complicated flows occurring in bends are described in detail, because of their increasing importance for modern cooling designs. A short review about testing of cooling design elements is given, showing the interaction of the different cooling features as well. The special focus of the present review has been put on the cooling of blades for heavy-duty gas turbines, which show several differences compared to aero-engine blades.

  10. Heat-transfer distributions on biconics at incidence in hypersonic-hypervelocity He, N2, air, and CO2 flows

    NASA Technical Reports Server (NTRS)

    Miller, C. G.; Micol, J. R.; Gnoffo, P. A.; Wilder, S. E.

    1983-01-01

    Laminar heat transfer rates were measured on spherically blunted, 13 deg/7 deg on axis and bent biconics (fore cone bent 7 deg upward relative to aft cone) at hypersonic hypervelocity flow conditions in the Langley Expansion Tube. Freestream velocities from 4.5 to 6.9 km/sec and Mach numbers from 6 to 9 were generated using helium, nitrogen, air, and carbon dioxide test gases, resulting in normal shock density ratios from 4 to 19. Angle of attack, referenced to the axis of the aft cone, was varied from 0 to 20 deg in 4 deg increments. The effect of nose bend, angle of attack, and real gas phenomena on heating distributions are presented along with comparisons of measurement to prediction from a code which solves the three dimensional parabolized Navier-Stokes equations.

  11. The role of air pollution in the relationship between a heat stress index and human mortality in Toronto.

    PubMed

    Rainham, Daniel G C; Smoyer-Tomic, Karen E

    2003-09-01

    In this study we considered confounding from air pollutants and chronological variables in the relation between humidex, a summer temperature and humidity index, and nonaccidental mortality, from 1980-1996 in Toronto, Canada. Changes in the risk of death by age group, gender, and combined cardiac-respiratory cause of death were estimated for both 1 degree C and 50-95th percentile increases in humidex using a generalized additive linear model. With air pollution terms in the models, relative risk (RR) point estimates narrowly exceeded 1.0 for all groups. Humidex effects were most apparent for females (RR=1.006, 95% CI=1.004-1.008 per 1 degree C humidex and RR=1.089, 95% CI=1.058-1.121 for 50th to 95th percentile humidex). When air pollution was omitted from the model, RR in the 50-95th percentile analysis increased less than 1.71% for all groups except females, for which RR decreased 1.42%. Differences in RR per 1 degree C humidex were all less than 0.12%. Confidence intervals narrowed slightly for all groups investigated. Heat stress has a statistically significant, yet minimal impact on Toronto populations, and air pollution does appear to have a small, but consistent confounding effect on humidex effect estimates.

  12. Energy Savings Potential and Research, Development, & Demonstration Opportunities for Residential Building Heating, Ventilation, and Air Conditioning Systems

    SciTech Connect

    Goetzler, William; Zogg, Robert; Young, Jim; Schmidt, Justin

    2012-10-01

    This report is an assessment of 135 different heating, ventilation, and air-conditioning (HVAC) technologies for U.S. residential buildings to identify and provide analysis on 19 priority technology options in various stages of development. The analyses include an estimation of technical energy-savings potential, descriptions of technical maturity, descriptions of non-energy benefits, descriptions of current barriers for market adoption, and descriptions of the technology's applicability to different building or HVAC equipment types. From these technology descriptions, are suggestions for potential research, development and demonstration (RD&D) initiatives that would support further development of the priority technology options.

  13. Energy Savings Potential and Research, Development, & Demonstration Opportunities for Commercial Building Heating, Ventilation, and Air Conditioning Systems

    SciTech Connect

    none,

    2011-09-01

    This report covers an assessment of 182 different heating, ventilation, and air-conditioning (HVAC) technologies for U.S. commercial buildings to identify and provide analysis on 17 priority technology options in various stages of development. The analyses include an estimation of technical energy-savings potential, description of technical maturity, description of non-energy benefits, description of current barriers for market adoption, and description of the technology’s applicability to different building or HVAC equipment types. From these technology descriptions, are suggestions for potential research, development and demonstration (RD&D) initiatives that would support further development of the priority technology options.

  14. Review and status of heat-transfer technology for internal passages of air-cooled turbine blades

    NASA Technical Reports Server (NTRS)

    Yeh, F. C.; Stepka, F. S.

    1984-01-01

    Selected literature on heat-transfer and pressure losses for airflow through passages for several cooling methods generally applicable to gas turbine blades is reviewed. Some useful correlating equations are highlighted. The status of turbine-blade internal air-cooling technology for both nonrotating and rotating blades is discussed and the areas where further research is needed are indicated. The cooling methods considered include convection cooling in passages, impingement cooling at the leading edge and at the midchord, and convection cooling in passages, augmented by pin fins and the use of roughened internal walls.

  15. Heat transfer and fluid dynamics of air-water two-phase flow in micro-channels

    SciTech Connect

    Kaji, Masuo; Sawai, Toru; Kagi, Yosuke; Ueda, Tadanobu

    2010-05-15

    Heat transfer, pressure drop, and void fraction were simultaneously measured for upward heated air-water non-boiling two-phase flow in 0.51 mm ID tube to investigate thermo-hydro dynamic characteristics of two-phase flow in micro-channels. At low liquid superficial velocity j{sub l} frictional pressure drop agreed with Mishima-Hibiki's correlation, whereas agreed with Chisholm-Laird's correlation at relatively high j{sub l}. Void fraction was lower than the homogeneous model and conventional empirical correlations. To interpret the decrease of void fraction with decrease of tube diameter, a relation among the void fraction, pressure gradient and tube diameter was derived. Heat transfer coefficient fairly agreed with the data for 1.03 and 2.01 mm ID tubes when j{sub l} was relatively high. But it became lower than that for larger diameter tubes when j{sub l} was low. Analogy between heat transfer and frictional pressure drop was proved to hold roughly for the two-phase flow in micro-channel. But satisfactory relation was not obtained under the condition of low liquid superficial velocity. (author)

  16. 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.

  17. A Comparative Study of Weights and Sizes of Flat-Plate Exhaust-Gas-to-Air Heat Exchangers with and without Fins

    DTIC Science & Technology

    1947-07-01

    tests of both heat exchangers, air or-d exhauj’t-gaa flow rates wtre mnr.sur’sd with venturi motors located downstream from the heat exchanger. Air...cas— flow ratoa aa di.torrin.jd froo the venturi notor. TEST rBOCEDUPE Flii^it toatJn3 of tho host exchangers wr.3 conduced to evaluate their tho...Static pressures upstrean and downctroTa frca tho hoat- oxchangor core wore raacurod with etat5c tubos , and air flow rates ware raacurcd vith n vonturi

  18. Quantifying the impact of residential heating on the urban air quality in a typical European coal combustion region.

    PubMed

    Junninen, Heikki; Mønster, Jacob; Rey, Maria; Cancelinha, Jose; Douglas, Kevin; Duane, Matthew; Forcina, Victtorio; Müller, Anne; Lagler, Fritz; Marelli, Luisa; Borowiak, Annette; Niedzialek, Joanna; Paradiz, Bostian; Mira-Salama, Daniel; Jimenez, Jose; Hansen, Ute; Astorga, Covadonga; Stanczyk, Krzysztof; Viana, Mar; Querol, Xavier; Duvall, Rachelle M; Norris, Gary A; Tsakovski, Stefan; Wåhlin, Peter; Horák, Jiri; Larsen, Bo R

    2009-10-15

    The present investigation, carried out as a case study in a typical major city situated in a European coal combustion region (Krakow, Poland), aims at quantifying the impact on the urban air quality of residential heating by coal combustion in comparison with other potential pollution sources such as power plants, industry, and traffic. Emissions were measured for 20 major sources, including small stoves and boilers, and the particulate matter (PM) was analyzed for 52 individual compounds together with outdoor and indoor PM10 collected during typical winter pollution episodes. The data were analyzed using chemical mass balance modeling (CMB) and constrained positive matrix factorization (CMF) yielding source apportionments for PM10, B(a)P, and other regulated air pollutants namely Cd, Ni, As, and Pb. The results are potentially very useful for planning abatement strategies in all areas of the world, where coal combustion in small appliances is significant. During the studied pollution episodes in Krakow, European air quality limits were exceeded with up to a factor 8 for PM10 and up to a factor 200 for B(a)P. The levels of these air pollutants were accompanied by high concentrations of azaarenes, known markers for inefficient coal combustion. The major culprit for the extreme pollution levels was demonstrated to be residential heating by coal combustion in small stoves and boilers (>50% for PM10 and >90% B(a)P), whereas road transport (<10% for PM10 and <3% for B(a)P), and industry (4-15% for PM10 and <6% for B(a)P) played a lesser role. The indoor PM10 and B(a)P concentrations were at high levels similar to those of outdoor concentrations and were found to have the same sources as outdoors. The inorganic secondary aerosol component of PM10 amounted to around 30%, which for a large part may be attributed to the industrial emission of the precursors SO2 and NOx.

  19. Development and Design of a User Interface for a Computer Automated Heating, Ventilation, and Air Conditioning System

    SciTech Connect

    Anderson, B.; /Fermilab

    1999-10-08

    A user interface is created to monitor and operate the heating, ventilation, and air conditioning system. The interface is networked to the system's programmable logic controller. The controller maintains automated control of the system. The user through the interface is able to see the status of the system and override or adjust the automatic control features. The interface is programmed to show digital readouts of system equipment as well as visual queues of system operational statuses. It also provides information for system design and component interaction. The interface is made easier to read by simple designs, color coordination, and graphics. Fermi National Accelerator Laboratory (Fermi lab) conducts high energy particle physics research. Part of this research involves collision experiments with protons, and anti-protons. These interactions are contained within one of two massive detectors along Fermilab's largest particle accelerator the Tevatron. The D-Zero Assembly Building houses one of these detectors. At this time detector systems are being upgraded for a second experiment run, titled Run II. Unlike the previous run, systems at D-Zero must be computer automated so operators do not have to continually monitor and adjust these systems during the run. Human intervention should only be necessary for system start up and shut down, and equipment failure. Part of this upgrade includes the heating, ventilation, and air conditioning system (HVAC system). The HVAC system is responsible for controlling two subsystems, the air temperatures of the D-Zero Assembly Building and associated collision hall, as well as six separate water systems used in the heating and cooling of the air and detector components. The BYAC system is automated by a programmable logic controller. In order to provide system monitoring and operator control a user interface is required. This paper will address methods and strategies used to design and implement an effective user interface

  20. Assessing Public Health Impacts of Heat and Air Quality Under a Changing Climate in the New York City Metropolitan Area

    NASA Astrophysics Data System (ADS)

    Knowlton, K.; Kinney, P. L.; Rosenthal, J. E.; Lynn, B.; Gaffin, S.; Hogrefe, C.; Biswas, J.; Civerolo, K.; Ku, J.; Rosenzweig, C.; Goldberg, R.

    2003-12-01

    New tools are needed for assessing public health impacts of climate change. This paper describes the results of an integrated assessment of the health impacts of global climate change in the New York metropolitan region, projected for the decade of the 2050s. The model systems used for this study are the Goddard Institute for Space Studies (GISS) Global Atmosphere-Ocean Model; the Penn State/NCAR MM5 mesoscale meteorological model; the Sparse Matrix Operator Kernel Emissions Modeling System (SMOKE); and the Community Multiscale Air Quality (CMAQ) model for simulating air quality. Simulations are performed for five summer seasons each during the 1990s and the 2050s, using greenhouse gas emissions projections from the Intergovernmental Panel on Climate Change (IPCC) A2 scenario. The GISS global climate model at 4 x 5 degree horizontal resolution is used as input to the MM5 model run at nested grids down to 36 km resolution. The MM5 at 36 km subsequently serves as input for the CMAQ ozone simulations. A risk assessment modeling framework is used to estimate summer heat- and ozone-related mortality in the region, with a focus on comparing respective estimates for the 1990s versus the 2050s. These endpoints represent two potentially appreciable public health impacts resulting from climate change-induced alterations in regional temperature and air quality profiles. Concentration-response functions from the epidemiological literature describing temperature-mortality and ozone-mortality relationships are applied in the risk assessment, to estimate numbers of regional deaths in a typical 1990s summer and a typical 2050s summer. An evaluation to define ozone-related mortality uses a minimum-value threshold applied across the 1-hour daily maximum ozone model outputs, to identify days that pose an elevated relative risk of ozone mortality. A parallel evaluation of heat-related mortality applies a 23.08° C (73.54° F) threshold value, above which the relative risk of heat