WorldWideScience

Sample records for satellite refrigerator heat

  1. Refrigeration waste heat recovery

    Energy Technology Data Exchange (ETDEWEB)

    1983-03-01

    UK Super A Stores was built in 1972 and is part of a small indoor shopping complex linked together by a heated mall. The store has a public floor area of approximately 1,232 m{sup 2} (13,261 ft.{sup 2}) and sells the usual variety of food produce including a large selection of frozen foods. There are five lengths of refrigerated display cabinets with a total area of approximately 78 m{sup 2}. There are also some frozen food storage rooms at the back of the store. This report provides a description of a waste heat recovery system within a medium sized food store. It details how the waste heat that is produced by the conventional frozen food display cabinets, can be reused by the store's space heating system. Recommended uses for this waste heat include: diverting to the loading bays which would make the reheat coil unnecessary, diverting to the front of the shop, and heating the adjacent shopping mall. The CREDA (Conservation and Renewable Energy Demonstration Assistance) program contributed $17,444 towards the total project cost of $30,444. The project was initiated by the store owner, who is now realizing a lower annual fuel consumption, with the resulting financial savings. 11 figs., 1 tab.

  2. Control of the Tevatron Satellite Refrigeration system

    International Nuclear Information System (INIS)

    Theilacker, J.; Chapman, L.; Gannon, J.; Hentges, M.; Martin, M.; Rode, C.H.; Zagel, J.

    1984-01-01

    This chapter describes a computerized control system for 24 satellite refrigerators which cool a six kilometer ring of superconducting magnets. The control system consists of 31 independent microprocessors operating over 400 servo loops, and a central computer system which provides monitoring, alarms, logging and changing of parameters. Topics considered include pressure measurement, flow measurement, temperature measurement, gas analysis, control valves, expansion engine controllers, and control loops. Each refrigerator has 12 active microprocessor based control loops which tune the refrigerator to one of its four operating modes: satellite, liquefier, refrigerator, and stand-by. It is suggested that optimizing the refrigerator control loops and quench recovery scheme will minimize the accelerator down time

  3. Refrigerant charge management in a heat pump water heater

    Science.gov (United States)

    Chen, Jie; Hampton, Justin W.

    2014-06-24

    Heat pumps that heat or cool a space and that also heat water, refrigerant management systems for such heat pumps, methods of managing refrigerant charge, and methods for heating and cooling a space and heating water. Various embodiments deliver refrigerant gas to a heat exchanger that is not needed for transferring heat, drive liquid refrigerant out of that heat exchanger, isolate that heat exchanger against additional refrigerant flowing into it, and operate the heat pump while the heat exchanger is isolated. The heat exchanger can be isolated by closing an electronic expansion valve, actuating a refrigerant management valve, or both. Refrigerant charge can be controlled or adjusted by controlling how much liquid refrigerant is driven from the heat exchanger, by letting refrigerant back into the heat exchanger, or both. Heat pumps can be operated in different modes of operation, and segments of refrigerant conduit can be interconnected with various components.

  4. Boiling Heat Transfer to Halogenated Hydrocarbon Refrigerants

    Science.gov (United States)

    Yoshida, Suguru; Fujita, Yasunobu

    The current state of knowledge on heat transfer to boiling refrigerants (halogenated hydrocarbons) in a pool and flowing inside a horizontal tube is reviewed with an emphasis on information relevant to the design of refrigerant evaporators, and some recommendations are made for future research. The review covers two-phase flow pattern, heat transfer characteristics, correlation of heat transfer coefficient, influence of oil, heat transfer augmentation, boiling from tube-bundle, influence of return bend, burnout heat flux, film boiling, dryout and post-dryout heat transfer.

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

    Science.gov (United States)

    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…

  6. Manufacturing A Refrigerator with Heat Recovery Unit

    Directory of Open Access Journals (Sweden)

    Mustafa Mohammed Kadhim

    2018-02-01

    Full Text Available This study aims to exploite the rejected heating energy from condenser and benefit from it to reheat the foods and other materials. It can also be employed to improve the coefficient of performance of a refrigerator at the same time by using approximately the same consumption electrical energy used to operate the compressor and refrigerator in general. This idea has been implemented by manufacturing of a refrigerator with using additional part has the same metal and condenser pipe diameters but its surface area does not exceed 40% from total surface area of the condenser and its design as an insulated cabinet from all sides to prevent heat leakage through it and located between the compressor and the condenser. Small electrical fan has been added inside this cabinet to provide a suitable air circulation and a homogenous temperature distribution inside the cabinet space. It is expected that the super heating energy of refrigerant (R134a which comes out of the compressor would be removed  inside this cabinet and this insist to condensate the refrigerant (cooling fluid with a rate higher than that used in the normal refrigerator only. Three magnetic valves have been used in order to control the refrigerant flow in state of operation the refrigerator only or to gather with heating cabinet. To measure the temperatures at each process of the simple vapor compression refrigeration cycle, nine temperature sensors at input and output of each compressor, condenser and an evaporator in additional to input of cabinet and inside it and on evaporator surface have been provided. Five pressure gages have been used to measure the value of pressure and compare it for the two states of operation. The consumption of electrical energy  can be calculated by adding an ammeter and a voltmeter and compare between the consumption energy of both states. The obtained results show that there is an improvement in the coeffecient of performance in state of operation the

  7. Nuclear heat sources for cryogenic refrigerator applications

    International Nuclear Information System (INIS)

    Raab, B.; Schock, A.; King, W.G.; Kline, T.; Russo, F.A.

    1975-01-01

    Spacecraft cryogenic refrigerators require thermal inputs on the order of 1000 W. First, the characteristics of solar-electric and radioisotope heat source systems for supplying this thermal input are compared. Then the design of a 238 Pu heat source for this application is described, and equipment for shipping and handling the heat source is discussed. (LCL)

  8. Refrigeration Playbook. Heat Reclaim; Optimizing Heat Rejection and Refrigeration Heat Reclaim for Supermarket Energy Conservation

    Energy Technology Data Exchange (ETDEWEB)

    Reis, Chuck [CTA Architects Engineers, Boise, ID (United States); Nelson, Eric [CTA Architects Engineers, Boise, ID (United States); Armer, James [CTA Architects Engineers, Boise, ID (United States); Johnson, Tim [CTA Architects Engineers, Boise, ID (United States); Hirsch, Adam [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Doebber, Ian [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2015-03-01

    The purpose of this playbook and accompanying spreadsheets is to generalize the detailed CBP analysis and to put tools in the hands of experienced refrigeration designers to evaluate multiple applications of refrigeration waste heat reclaim across the United States. Supermarkets with large portfolios of similar buildings can use these tools to assess the impact of large-scale implementation of heat reclaim systems. In addition, the playbook provides best practices for implementing heat reclaim systems to achieve the best long-term performance possible. It includes guidance on operations and maintenance as well as measurement and verification.

  9. Quantum heat engines and refrigerators: continuous devices.

    Science.gov (United States)

    Kosloff, Ronnie; Levy, Amikam

    2014-01-01

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

  10. Literature survey of heat transfer enhancement techniques in refrigeration applications

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, M.K.; Shome, B. [Rensselaer Polytechnic Inst., Troy, NY (United States). Dept. of Mechanical Engineering, Aeronautical Engineering and Mechanics

    1994-05-01

    A survey has been performed of the technical and patent literature on enhanced heat transfer of refrigerants in pool boiling, forced convection evaporation, and condensation. Extensive bibliographies of the technical literature and patents are given. Many passive and active techniques were examined for pure refrigerants, refrigerant-oil mixtures, and refrigerant mixtures. The citations were categorized according to enhancement technique, heat transfer mode, and tube or shell side focus. The effects of the enhancement techniques relative to smooth and/or pure refrigerants were illustrated through the discussion of selected papers. Patented enhancement techniques also are discussed. Enhanced heat transfer has demonstrated significant improvements in performance in many refrigerant applications. However, refrigerant mixtures and refrigerant-oil mixtures have not been studied extensively; no research has been performed with enhanced refrigerant mixtures with oil. Most studies have been of the parametric type; there has been inadequate examination of the fundamental processes governing enhanced refrigerant heat transfer, but some modeling is being done and correlations developed. It is clear that an enhancement technique must be optimized for the refrigerant and operating condition. Fundamental processes governing the heat transfer must be examined if models for enhancement techniques are to be developed; these models could provide the method to optimize a surface. Refrigerant mixtures, with and without oil present, must be studied with enhancement devices; there is too little known to be able to estimate the effects of mixtures (particularly NARMs) with enhanced heat transfer. Other conclusions and recommendations are offered.

  11. IEA Annex 26: Advanced Supermarket Refrigeration/Heat Recovery Systems

    Energy Technology Data Exchange (ETDEWEB)

    Baxter, VAN

    2003-05-19

    With increased concern about the impact of refrigerant leakage on global warming, a number of new supermarket refrigeration system configurations requiring significantly less refrigerant charge are being considered. In order to help promote the development of advanced systems and expand the knowledge base for energy-efficient supermarket technology, the International Energy Agency (IEA) established IEA Annex 26 (Advanced Supermarket Refrigeration/Heat Recovery Systems) under the ''IEA Implementing Agreement on Heat Pumping Technologies''. Annex 26 focuses on demonstrating and documenting the energy saving and environmental benefits of advanced systems design for food refrigeration and space heating and cooling for supermarkets. Advanced in this context means systems that use less energy, require less refrigerant and produce lower refrigerant emissions. Stated another way, the goal is to identify supermarket refrigeration and HVAC technology options that reduce the total equivalent warming impact (TEWI) of supermarkets by reducing both system energy use (increasing efficiency) and reducing total refrigerant charge. The Annex has five participating countries: Canada, Denmark, Sweden, the United Kingdom, and the United States. The working program of the Annex has involved analytical and experimental investigation of several candidate system design approaches to determine their potential to reduce refrigerant usage and energy consumption. Advanced refrigeration system types investigated include the following: distributed compressor systems--small parallel compressor racks are located in close proximity to the food display cases they serve thus significantly shortening the connecting refrigerant line lengths; secondary loop systems--one or more central chillers are used to refrigerate a secondary coolant (e.g. brine, ice slurry, or CO2) that is pumped to the food display cases on the sales floor; self-contained display cases--each food display case

  12. Miniaturized Air-to-Refrigerant Heat Exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Radermacher, Reinhard [Univ. of Maryland, College Park, MD (United States); Bacellar, Daniel [Univ. of Maryland, College Park, MD (United States); Aute, Vikrant [Univ. of Maryland, College Park, MD (United States); Huang, Zhiwei [Univ. of Maryland, College Park, MD (United States); Hwang, Yunho [Univ. of Maryland, College Park, MD (United States); Ling, Jiazhen [Univ. of Maryland, College Park, MD (United States); Muehlbauer, Jan [Univ. of Maryland, College Park, MD (United States); Tancabel, James [Univ. of Maryland, College Park, MD (United States); Abdelaziz, Omar [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Zhang, Mingkan [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-05-23

    Air-to-refrigerant Heat eXchangers (HX) are an essential component of Heating, Ventilation, Air-Conditioning, and Refrigeration (HVAC&R) systems, serving as the main heat transfer component. The major limiting factor to HX performance is the large airside thermal resistance. Recent literature aims at improving heat transfer performance by utilizing enhancement methods such as fins and small tube diameters; this has lead to almost exhaustive research on the microchannel HX (MCHX). The objective of this project is to develop a miniaturized air-to-refrigerant HX with at least 20% reduction in volume, material volume, and approach temperature compared to current state-of-the-art multiport flat tube designs and also be capable of production within five years. Moreover, the proposed HX’s are expected to have good water drainage and should succeed in both evaporator and condenser applications. The project leveraged Parallel-Parametrized Computational Fluid Dynamics (PPCFD) and Approximation-Assisted Optimization (AAO) techniques to perform multi-scale analysis and shape optimization with the intent of developing novel HX designs whose thermal-hydraulic performance exceeds that of state-of-the-art MCHX. Nine heat exchanger geometries were initially chosen for detailed analysis, selected from 35+ geometries which were identified in previous work at the University of Maryland, College Park. The newly developed optimization framework was exercised for three design optimization problems: (DP I) 1.0kW radiator, (DP II) 10kW radiator and (DP III) 10kW two-phase HX. DP I consisted of the design and optimization of 1.0kW air-to-water HX’s which exceeded the project requirements of 20% volume/material reduction and 20% better performance. Two prototypes for the 1.0kW HX were prototyped, tested and validated using newly-designed airside and refrigerant side test facilities. DP II, a scaled version DP I for 10kW air-to-water HX applications, also yielded optimized HX designs

  13. Advanced Supermarket Refrigeration/Heat Recovery Systems. Country Report, Denmark

    DEFF Research Database (Denmark)

    Knudsen, Hans-Jørgen Høgaard; Christensen, K. G.

    Annex 26 is the first international project under the IEA Heat Pump Programme that links refrigeration and heat pump technology. Recovering heat from advanced supermarket refrigeration systems for space and water heating seems obvious and is beneficial for owners and operators. Because the great...... number of supermarkets that offer frozen and chilled food and further growth of this sector may be expected, the amount of energy used for refrigeration is enormous and will likely increase in the near future. Annex 26 analysed several advanced supermarket refrigeration systems and came to remarkable...... conclusions as far energy conservation and TEWI reduction is concerned. The conclusion justify that advanced supermarket systems with heat recovery should receive great attention and support. And there is still further research needed in several areas. The Annex also included a thorough system analyses...

  14. Satellite Ocean Heat Content Suite

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This collection contains an operational Satellite Ocean Heat Content Suite (SOHCS) product generated by NOAA National Environmental Satellite, Data, and Information...

  15. Overall conductance and heat transfer area minimization of refrigerators and heat pumps with finite heat reservoirs

    International Nuclear Information System (INIS)

    Sarkar, J.; Bhattacharyya, Souvik

    2007-01-01

    In the present study, the overall conductance and the overall heat transfer area per unit capacity of refrigeration and heat pump systems have been minimized analytically considering both internal and external irreversibilities with variable temperature (finite capacity) heat reservoirs. Hot and cold side refrigerant temperatures, conductance and heat transfer area ratios have been optimized to attain this goal. The results have been verified with the more elaborate numerical optimization results obtained for ammonia based vapour compression refrigeration and heat pump systems working with variable temperature reservoirs. It is observed that the analytical results for optimum refrigerant temperatures, minimum overall conductance and heat transfer area deviate marginally from the numerically optimized results (within 1%), if one assumes a constant heat rejection temperature. The deviation of minimum overall conductance and heat transfer area is more (about 20%), if one considers both the desuperheating and condensation regions separately. However, in the absence of complex and elaborate numerical models, the simple analytical results obtained here can be used as reasonably accurate preliminary guidelines for optimization of refrigeration and heat pump systems

  16. Thermodynamic Heat Water by The Condenser of Refrigerator

    International Nuclear Information System (INIS)

    Ben Slama, Romdhane

    2009-01-01

    The present innovation relates to the coupling of a refrigerator to a cumulus to heat water and this, thanks to the heat yielded to the level of the condenser of the refrigerating system even. The heating of water is carried out thus without energy over consumption. The quantity of heat transferred by the water-cooled condenser is sufficient to raise the temperature of this latter with 60 degree at the end of five hours. This can satisfy completely or partially the requirements out of hot water of a family which can distribute its requirements out of hot water all along the day and the week. The quantity of heat recovered by water to heat rises with four multiples the power consumption by the compressor. The system thus makes it possible to save energy and to safeguard the environment

  17. Practical design of a heat exchanger for dilution refrigeration. 1

    Energy Technology Data Exchange (ETDEWEB)

    Oda, Y; Fujii, G; Nagano, H [Tokyo Univ. (Japan). Inst. for Solid State Physics

    1978-02-01

    A compact heat exchanger for a dilution refrigerator with a high thermal efficiency is presented. Discrete heat exchangers with by-pass channels were used to decrease the flow impedance. This heat exchanger was designed so that the thermal conductance of liquid along the stream was greatly reduced. The effective thickness of the sponge material in the heat exchanger and mixer is also discussed. The obtained minimum temperatures of 12 mK was very close to the designed value of 10.8 mK. Moreover a rapid response was obtained. This is attributed to the small liquid volume of the heat exchanger.

  18. TESTING OF REFRIGERANT MIXTURES IN RESIDENTIAL HEAT PUMPS

    Science.gov (United States)

    The report gives results of an investigation of four possibilities for replacing Hydrochlorofluorocarbon-22 (HCFC-22) with the non-ozone-depleting new refrigerants R-407D and R-407C in residential heat pumps. The first and simplest scenario was a retrofit with no hardware modific...

  19. 49 CFR 176.93 - Vehicles having refrigerating or heating equipment.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Vehicles having refrigerating or heating equipment... Transported on Board Ferry Vessels § 176.93 Vehicles having refrigerating or heating equipment. (a) A transport vehicle fitted with refrigerating or heating equipment using a flammable liquid or Division 2.1...

  20. Pressure heat pumping in the orifice pulse-tube refrigerator

    International Nuclear Information System (INIS)

    Boer, P.C.T. de

    1996-01-01

    The mechanism by which heat is pumped as a result of pressure changes in an orifice pulse-tube refrigerator (OPTR) is analyzed thermodynamically. The thermodynamic cycle considered consists of four steps: (1) the pressure is increased by a factor π 1 due to motion of a piston in the heat exchanger at the warm end of the regenerator; (2) the pressure is decreased by a factor π 2 due to leakage out of the orifice; (3) the pressure is further decreased due to motion of the piston back to its original position; (4) the pressure is increased to its value at the start of the cycle due to leakage through the orifice back into the pulse tube. The regenerator and the heat exchangers are taken to be perfect. The pressure is assumed to be uniform during the entire cycle. The temperature profiles of the gas in the pulse tube after each step are derived analytically. Knowledge of the temperature at which gas enters the cold heat exchanger during steps 3 and 4 provides the heat removed per cycle from this exchanger. Knowledge of the pressure as a function of piston position provides the work done per cycle by the piston. The pressure heat pumping mechanism considered is effective only in the presence of a regenerator. Detailed results are presented for the heat removed per cycle, for the coefficient of performance, and for the refrigeration efficiency as a function of the compression ratio π 1 and the expansion ratio π 2 . Results are also given for the influence on performance of the ratio of specific heats. The results obtained are compared with corresponding results for the basic pulse-tube refrigerator (BPTR) operating by surface heat pumping

  1. Recent evolutions of refrigerating machineries and heat pumps; Evolutions recentes des machines a froid et thermopompes

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-12-31

    This book of proceedings reports on 10 papers (or series of transparencies) concerning some recent developments about refrigerating machineries and heat pumps as used in space heating, air-conditioning and industrial refrigeration. Various aspects are developed: thermodynamic cycles, thermal performances, dimensioning, modeling, refrigerants substitution, design of flanged exchangers, compressors etc.. (J.S.)

  2. Recent evolutions of refrigerating machineries and heat pumps; Evolutions recentes des machines a froid et thermopompes

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-31

    This book of proceedings reports on 10 papers (or series of transparencies) concerning some recent developments about refrigerating machineries and heat pumps as used in space heating, air-conditioning and industrial refrigeration. Various aspects are developed: thermodynamic cycles, thermal performances, dimensioning, modeling, refrigerants substitution, design of flanged exchangers, compressors etc.. (J.S.)

  3. Possibility of using adsorption refrigeration unit in district heating network

    Science.gov (United States)

    Grzebielec, Andrzej; Rusowicz, Artur; Jaworski, Maciej; Laskowski, Rafał

    2015-09-01

    Adsorption refrigeration systems are able to work with heat sources of temperature starting with 50 °C. The aim of the article is to determine whether in terms of technical and economic issues adsorption refrigeration equipment can work as elements that produce cold using hot water from the district heating network. For this purpose, examined was the work of the adsorption air conditioning equipment cooperating with drycooler, and the opportunities offered by the district heating network in Warsaw during the summer. It turns out that the efficiency of the adsorption device from the economic perspective is not sufficient for production of cold even during the transitional period. The main problem is not the low temperature of the water supply, but the large difference between the coefficients of performance, COPs, of adsorption device and a traditional compressor air conditioning unit. When outside air temperature is 25 °C, the COP of the compressor type reaches a value of 4.49, whereas that of the adsorption device in the same conditions is 0.14. The ratio of the COPs is 32. At the same time ratio between the price of 1 kWh of electric power and 1 kWh of heat is only 2.85. Adsorption refrigeration equipment to be able to compete with compressor devices, should feature COPads efficiency to be greater than 1.52. At such a low driving temperature and even changing the drycooler into the evaporative cooler it is not currently possible to achieve.

  4. Reassessment of forced convection heat transfer correlations for refrigerant-12

    International Nuclear Information System (INIS)

    Celata, G.P.; Cuomo, M.; D'Annibale, F.; Farello, G.E.; Setaro, T.

    1986-01-01

    In the frame of a Refrigerant-12 experiment on postulated accidental transients in Pressurized Water Reactors under way at Heat Transfer Laboratory (ENEA Casaccia Research Center), an assessment of the main correlation available in scientific literature, for the different heat transfer regions encountered when a liquid is boiled in a confined heated channel, has been performed. Considering a vertical tube uniformly heated over its length with CHF at the exit, the following heat transfer regimes may be individuated: convective heat transfer to liquid, subcooled boiling, saturated nucleate boiling, forced convective heat transfer through liquid film (annular flow regime) and thermal crisis. From the comparison of computed values with an original ENEA dataset, the best correlations in predicting Refrigerant-12 data have been individuated. In a few cases, though preserving the original structure of the correlations, mainly developed for water, it was necessary to adjust some coefficients by means of best-fit procedures through our experimental data. The work has been performed in the frame of the ENEA Thermal Reactor Department Safety Research Project

  5. Possibility of using adsorption refrigeration unit in district heating network

    Directory of Open Access Journals (Sweden)

    Grzebielec Andrzej

    2015-09-01

    Full Text Available Adsorption refrigeration systems are able to work with heat sources of temperature starting with 50 °C. The aim of the article is to determine whether in terms of technical and economic issues adsorption refrigeration equipment can work as elements that produce cold using hot water from the district heating network. For this purpose, examined was the work of the adsorption air conditioning equipment cooperating with drycooler, and the opportunities offered by the district heating network in Warsaw during the summer. It turns out that the efficiency of the adsorption device from the economic perspective is not sufficient for production of cold even during the transitional period. The main problem is not the low temperature of the water supply, but the large difference between the coefficients of performance, COPs, of adsorption device and a traditional compressor air conditioning unit. When outside air temperature is 25 °C, the COP of the compressor type reaches a value of 4.49, whereas that of the adsorption device in the same conditions is 0.14. The ratio of the COPs is 32. At the same time ratio between the price of 1 kWh of electric power and 1 kWh of heat is only 2.85. Adsorption refrigeration equipment to be able to compete with compressor devices, should feature COPads efficiency to be greater than 1.52. At such a low driving temperature and even changing the drycooler into the evaporative cooler it is not currently possible to achieve.

  6. Heat transfer and pressure drop during hydrocarbon refrigerant condensation inside a brazed plate heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Longo, Giovanni A. [University of Padova, Department of Management and Engineering, Str.lla S.Nicola 3, I-36100 Vicenza (Italy)

    2010-08-15

    This paper presents the heat transfer coefficients and pressure drop measured during HC-600a, HC-290 and HC-1270 saturated vapour condensation inside a brazed plate heat exchanger: the effects of refrigerant mass flux, saturation temperature (pressure) and fluid properties are investigated. The heat transfer coefficients show weak sensitivity to saturation temperature (pressure) and great sensitivity to refrigerant mass flux and fluid properties. A transition point between gravity controlled and forced convection condensation has been found for a refrigerant mass flux around 15-18 kg m{sup -2} s{sup -1}. In the forced convection condensation region the heat transfer coefficients show a 35-40% enhancement for a 60% increase of the refrigerant mass flux. The frictional pressure drop shows a linear dependence on the kinetic energy per unit volume of the refrigerant flow. HC-1270 shows heat transfer coefficients 5% higher than HC-600a and 10-15% higher than HC-290, together with frictional pressure drop 20-25% lower than HC-290 and 50-66% lower than HC-600a. (author)

  7. Micro-structured heat exchanger for cryogenic mixed refrigerant cycles

    Science.gov (United States)

    Gomse, D.; Reiner, A.; Rabsch, G.; Gietzelt, T.; Brandner, J. J.; Grohmann, S.

    2017-12-01

    Mixed refrigerant cycles (MRCs) offer a cost- and energy-efficient cooling method for the temperature range between 80 and 200 K. The performance of MRCs is strongly influenced by entropy production in the main heat exchanger. High efficiencies thus require small temperature gradients among the fluid streams, as well as limited pressure drop and axial conduction. As temperature gradients scale with heat flux, large heat transfer areas are necessary. This is best achieved with micro-structured heat exchangers, where high volumetric heat transfer areas can be realized. The reliable design of MRC heat exchangers is challenging, since two-phase heat transfer and pressure drop in both fluid streams have to be considered simultaneously. Furthermore, only few data on the convective boiling and condensation kinetics of zeotropic mixtures is available in literature. This paper presents a micro-structured heat exchanger designed with a newly developed numerical model, followed by experimental results on the single-phase pressure drop and their implications on the hydraulic diameter.

  8. Control optimizations for heat recovery from CO2 refrigeration systems in supermarket

    International Nuclear Information System (INIS)

    Ge, Y.T.; Tassou, S.A.

    2014-01-01

    Highlights: • Application of supermarket energy control system model. • Heat recovery from CO 2 refrigeration system in supermarket space conditioning. • Effect of pressure controls of CO 2 refrigeration system on heat recovery potentials. • Control optimization of CO 2 refrigeration system for heat recovery in supermarket. - Abstract: A modern supermarket energy control system has a concurrent need for electricity, food refrigeration and space heating or cooling. Approximately 10% of this energy is for conventional gas-powered heating. In recent years, the use of CO 2 as a refrigerant in supermarket systems has received considerable attention due to its negligible contribution to direct greenhouse gas emissions and excellent thermophysical and heat transfer properties. CO 2 refrigeration systems also offer more compact component designs over a conventional HFC system and heat recovery potential from compressor discharge. In this paper, the heat recovery potential of an all-CO 2 cascade refrigeration system in a supermarket has been investigated using the supermarket simulation model “SuperSim” developed by the authors. It has been shown that at UK weather conditions, the heat recovery potential of CO 2 refrigeration systems can be increased by increasing the condenser/gas cooler pressure to the point where all the heat requirements are satisfied. However, the optimum level of heat recovery will vary during the year and the control system should be able to continuously optimize this level based on the relative cost of energy, i.e., gas and electricity

  9. Natural refrigerants. Future heat pumps for district heating; Naturliga koeldmedier. Framtida vaermepumpar foer fjaerrvaerme

    Energy Technology Data Exchange (ETDEWEB)

    Ingvarsson, Paul; Steen Ronnermark, Ingela [Fortum Teknik och Miljoe AB, Stockholm (Sweden); Eriksson, Marcus [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Chemical Engineering and Environmental Science

    2004-01-01

    International work on refrigerants is aiming at phasing out HFC. The solution might be natural refrigerants. Within 15-20 years, when present heat pumps for district heating in Sweden are likely not in service any longer, it might still be good economy to install new heat pumps since only the machines need to be replaced. This report describes the possibilities to use natural refrigerants. A first screening resulted in further study on some hydrocarbons, ammonia and carbon dioxide. Water was considered to require too large volumes. In present plants it is practically not possible to use any natural refrigerants, partly because the compressors are not adapted. In new plants the situation is different. Today it is technically possible to install new heat pumps in the studied size, 15 MW{sub th}, using ammonia or hydrocarbons as refrigerant. But likely it is very difficult to get permits from authorities since the refrigerants are toxic or highly flammable. There is substantial international research on using carbon dioxide, and this refrigerant is also used in some applications. Carbon dioxide is used at high pressure and in a trans-critical process. Surprisingly, it turned out that one compressor manufacturer considers it possible to supply a heat pump for district heating within 5 years. This development has taken place in Russia, mainly for domestic use. Thus, within 15 to 20 years there will probably exist a technique where carbon dioxide is used. However, more development is needed. Additionally, low district heating return temperatures are also needed to get an acceptable COP. The investment cost for a heat pump installation is considered to be approx. 30 % higher when using ammonia or propane compared to using R134a. When using carbon dioxide there is in the longer run potential to get lower cost than for R134a. The COPs are almost identical if the systems are properly designed. In the carbon dioxide case the COP is somewhat lower, but has a potential for

  10. SIMULATION OF NON-AZEOTROPIC REFRIGERANT MIXTURES FOR USE IN A DUAL-CIRCUIT REFRIGERATOR/FREEZER WITH COUNTERCURRENT HEAT EXCHANGES

    Science.gov (United States)

    The paper discusses a refrigerator/freezer (RF) system that has two complete and independent refrigeration cycles for the two compartments. It uses a non-azeotropic refrigerant mixture (NARM) in each cycle and countercurrent heat exchangers throughout. This RF is housed in a stan...

  11. Simulation methods of rocket fuel refrigerating with liquid nitrogen and intermediate heat carrier

    Directory of Open Access Journals (Sweden)

    O. E. Denisov

    2014-01-01

    Full Text Available Temperature preparation of liquid propellant components (LPC before fueling the tanks of rocket and space technology is the one of the operations performed by ground technological complexes on cosmodromes. Refrigeration of high-boiling LPC is needed to increase its density and to create cold reserve for compensation of heat flows existing during fueling and prelaunch operations of space rockets.The method and results of simulation of LPC refrigeration in the recuperative heat exchangers with heat carrier which is refrigerated by-turn with liquid nitrogen sparging. The refrigerating system consists of two tanks (for the chilled coolant and LPC, LPC and heat carrier circulation loops with heat exchanger and system of heat carrier refrigeration in its tank with bubbler. Application of intermediate heat carrier between LPC and liquid nitrogen allows to avoid LPC crystallization on cold surfaces of the heat exchanger.Simulation of such systems performance is necessary to determine its basic design and functional parameters ensuring effective refrigerating of liquid propellant components, time and the amount of liquid nitrogen spent on refrigeration operation. Creating a simulator is quite complicated because of the need to take into consideration many different heat exchange processes occurring in the system. Also, to determine the influence of various parameters on occurring processes it is necessary to take into consideration the dependence of all heat exchange parameters on each other: heat emission coefficients, heat transfer coefficients, heat flow amounts, etc.The paper offers an overview of 10 references to foreign and Russian publications on separate issues and processes occurring in liquids refrigerating, including LPC refrigeration with liquid nitrogen. Concluded the need to define the LPC refrigerating conditions to minimize cost of liquid nitrogen. The experimental data presented in these publications is conformed with the application of

  12. Influence of special attributes of zeotropic refrigerant mixtures on design and operation of vapour compression refrigeration and heat pump systems

    International Nuclear Information System (INIS)

    Rajapaksha, Leelananda

    2007-01-01

    The use of zeotropic refrigerant mixtures introduces a number of novel issues that affect the established design and operational practices of vapour compression systems used in refrigeration, air conditioning and heat pump applications. Two attributes; composition shift and temperature glide, associated with the phase changing process of zeotropic mixtures are the primary phenomena that bring in these issues. However, relevant researches are uncovering ways how careful system designs and selection of operational parameters allow improving the energy efficiency and the capacity of vapour compression refrigeration systems. Most of these concepts exploit the presence of composition shift and temperature glide. This paper qualitatively discusses how the mixture attributes influence the established heat exchanger design practices, performance and operation of conventional vapour compression systems. How the temperature glide and composition shift can be incorporated to improve the system performance and the efficiency are also discussed

  13. Analytical minimization of overall conductance and heat transfer area in refrigeration and heat pump systems and its numerical confirmation

    International Nuclear Information System (INIS)

    Sarkar, J.; Bhattacharyya, Souvik; Ram Gopal, M.

    2007-01-01

    Minimization of heat exchanger area for a specified capacity is very important in the design of refrigeration and heat pump systems, yielding space, weight and cost benefits. In this study, minimization of overall conductance and total area per unit capacity of refrigeration and heat pump systems has been performed analytically. The analysis is performed for constant temperature heat sources and sinks considering both internal and external irreversibilities. Expressions are obtained for optimum hot and cold side refrigerant temperatures, conductance and heat exchanger area ratios. The analytical results have been confirmed by those obtained from a detailed numerical simulation of actual ammonia based refrigeration and heat pump systems, and good agreement is observed. Such theoretical models can be employed as simple yet effective design guidelines for real systems as demonstrated here

  14. COP improvement of refrigerator/freezers, air-conditioners, and heat pumps using nonazeotropic refrigerant mixtures

    Science.gov (United States)

    Westra, Douglas G.

    1993-01-01

    With the February, 1992 announcement by President Bush to move the deadline for outlawing CFC (chloro-fluoro-carbon) refrigerants from the year 2000 to the year 1996, the refrigeration and air-conditioning industries have been accelerating their efforts to find alternative refrigerants. Many of the alternative refrigerants being evaluated require synthetic lubricants, are less efficient, and have toxicity problems. One option to developing new, alternative refrigerants is to combine existing non-CFC refrigerants to form a nonazeotropic mixture, with the concentration optimized for the given application so that system COP (Coefficient Of Performance) may be maintained or even improved. This paper will discuss the dilemma that industry is facing regarding CFC phase-out and the problems associated with CFC alternatives presently under development. A definition of nonazeotropic mixtures will be provided, and the characteristics and COP benefits of nonazeotropic refrigerant mixtures will be explained using thermodynamic principles. Limitations and disadvantages of nonazeotropic mixtures will be discussed, and example systems using such mixtures will be reviewed.

  15. Investigation of waste heat recovery of binary geothermal plants using single component refrigerants

    Science.gov (United States)

    Unverdi, M.

    2017-08-01

    In this study, the availability of waste heat in a power generating capacity of 47.4 MW in Germencik Geothermal Power Plant has been investigated via binary geothermal power plant. Refrigerant fluids of 7 different single components such as R-134a, R-152a, R-227ea, R-236fa, R-600, R-143m and R-161 have been selected. The binary cycle has been modeled using the waste heat equaling to mass flow rate of 100 kg/s geothermal fluid. While the inlet temperature of the geothermal fluid into the counter flow heat exchanger has been accepted as 110°C, the outlet temperature has been accepted as 70°C. The inlet conditions have been determined for the refrigerants to be used in the binary cycle. Finally, the mass flow rate of refrigerant fluid and of cooling water and pump power consumption and power generated in the turbine have been calculated for each inlet condition of the refrigerant. Additionally, in the binary cycle, energy and exergy efficiencies have been calculated for 7 refrigerants in the availability of waste heat. In the binary geothermal cycle, it has been found out that the highest exergy destruction for all refrigerants occurs in the heat exchanger. And the highest and lowest first and second law efficiencies has been obtained for R-600 and R-161 refrigerants, respectively.

  16. Reversible and irreversible heat engine and refrigerator cycles

    Science.gov (United States)

    Leff, Harvey S.

    2018-05-01

    Although no reversible thermodynamic cycles exist in nature, nearly all cycles covered in textbooks are reversible. This is a review, clarification, and extension of results and concepts for quasistatic, reversible and irreversible processes and cycles, intended primarily for teachers and students. Distinctions between the latter process types are explained, with emphasis on clockwise (CW) and counterclockwise (CCW) cycles. Specific examples of each are examined, including Carnot, Kelvin and Stirling cycles. For the Stirling cycle, potentially useful task-specific efficiency measures are proposed and illustrated. Whether a cycle behaves as a traditional refrigerator or heat engine can depend on whether it is reversible or irreversible. Reversible and irreversible-quasistatic CW cycles both satisfy Carnot's inequality for thermal efficiency, η ≤ η C a r n o t . Irreversible CCW cycles with two reservoirs satisfy the coefficient of performance inequality K ≤ K C a r n o t . However, an arbitrary reversible cycle satisfies K ≥ K C a r n o t when compared with a reversible Carnot cycle operating between its maximum and minimum temperatures, a potentially counterintuitive result.

  17. Condensation of refrigerants in horizontal microfin tubes: comparison of prediction methods for heat transfer

    Energy Technology Data Exchange (ETDEWEB)

    Wang, H S; Honda, H [Kyushu University, Fukuoka (Japan). Institute of Advanced Material Study

    2003-06-01

    A comparison was made between the predictions of previously proposed empirical correlations and theoretical model and available experimental data for the heat transfer coefficient during condensation of refrigerants in horizontal microfin tubes. The refrigerants tested were R11, R123, R134a, R22 and R410A. Experimental data for six tubes with the tube inside diameter at fin root of 6.49-8.8 8 mm, the fin height of 0.16-0.24 mm, fin pitch of 0.34-0.53 mm and helix angle of groove of 12-20{sup o} were adopted. The r.m.s. error of the predictions for all tubes and all refrigerants decreased in the order of the correlations proposed by Luu and Bergies [ASHRAE Trans. 86 (1980) 293], Cavallini et al. Condensation of new refrigerants inside smooth and enhanced tubes. In: Proc. 19th Int. Cong. Refrigeration, vol. IV, Hague, The Netherlands, 1995. p. 105-114, Shikazono et al. [Trans. Jap. Sco. Mech. Engrs. 64 (1995) 196], Kedzierski and Goncalves [J. Enhanced Heat Transfer 6 (1999) 16], Yu and Koyama [Yu J, Koyama S. Condensation heat transfer of pure refrigerants in microfin tubes. In: Proc. Int. Refrigeration Conference at Purdue Univ., West Lafayette, USA, 1998. p. 325-330], and the theoretical model proposed by Wang et al. [Int. J. Heat Mass Transfer 45 (2002) 1513]. (author)

  18. AN EXPERIMENTAL STUDY ON A VAPOR COMPRESSION REFRIGERATION CYCLE BY ADDING INTERNAL HEAT EXCHANGER

    Directory of Open Access Journals (Sweden)

    Muhammad Asmail Eleiwi

    2013-05-01

    Full Text Available Thispaper presents practical study to improve the indication COP of a vaporcompression refrigeration cycle in instrumented automobile air conditioner bydesigning internal heat exchanger and installing it in the vapor compressionrefrigeration cycle.  Two cases of  vapor compression refrigeration cycle were takenin this paper:  the first case is thatthe vapor compression refrigeration cycle without internal heat exchanger andin  the second case the vapor compressionrefrigeration cycle with heat exchanger ; in these two cases, the temperatureat each point of  a vapor compressionrefrigeration cycle, the low and the high pressure ,the indoor temperature andthe outdoor temperature were measured at each time at compressor speed 1450 rpmand 2900 rpm for each blower speed 1, blower speed 2 and blower speed 3.Therefrigerant fluid was used in the vapor compression refrigeration cycle withoutIHE and with IHE is R134a..

  19. Universality of energy conversion efficiency for optimal tight-coupling heat engines and refrigerators

    International Nuclear Information System (INIS)

    Sheng, Shiqi; Tu, Z C

    2013-01-01

    A unified χ-criterion for heat devices (including heat engines and refrigerators), which is defined as the product of the energy conversion efficiency and the heat absorbed per unit time by the working substance (de Tomás et al 2012 Phys. Rev. E 85 010104), is optimized for tight-coupling heat engines and refrigerators operating between two heat baths at temperatures T c and T h ( > T c ). By taking a new convention on the thermodynamic flux related to the heat transfer between two baths, we find that for a refrigerator tightly and symmetrically coupled with two heat baths, the coefficient of performance (i.e., the energy conversion efficiency of refrigerators) at maximum χ asymptotically approaches √(ε C ) when the relative temperature difference between two heat baths ε C -1 ≡(T h -T c )/T c is sufficiently small. Correspondingly, the efficiency at maximum χ (equivalent to maximum power) for a heat engine tightly and symmetrically coupled with two heat baths is proved to be η C /2+η C 2 /8 up to the second order term of η C ≡ (T h − T c )/T h , which reverts to the universal efficiency at maximum power for tight-coupling heat engines operating between two heat baths at small temperature difference in the presence of left–right symmetry (Esposito et al 2009 Phys. Rev. Lett. 102 130602). (fast track communication)

  20. Utilization of the heat of mixing in open-circuit throttle refrigerators

    International Nuclear Information System (INIS)

    Zhakharov, N.D.; Anikeev, G.N.; Grezin, A.K.

    1986-01-01

    Open-circuit throttle refrigerators based on gas mixtures operate, as a rule, according to a single-stream scheme. The refrigerating effect is determined by the isothermal throttling effect of the mixture in the cylinder under the conditions at the inlet to the cryogenic unit. The authors use the heat of mixing of the cryogenic mixtures to increase the available refrigerating effect. Data are presented on mixtures of nitrogen and Freon-13; the thermodynamic properties of these compounds have been investigated experimentally over a wide range of parameters. It was found that in the case of correct selection of the scheme and complex optimization of the parameters, two-stream throttle refrigerators exceed the single-stream throttle refrigerators by at least a factor of 1.5 with respect to relative useful energy. With account taken of the design, technological, and operational parameters, that which is most promising is the scheme with mixing of the components in reverse flow

  1. Satellite refrigerator compressors with the oil and moisture removal systems

    International Nuclear Information System (INIS)

    Satti, J.A.

    1983-08-01

    There are twenty-eight compressors installed around the Main Accelerator Ring in seven locations. Drawing 9140-ME-129720 shows the piping and the components schematic for four Mycom compressor skids per building with each having an independent oil and moisture removal system. The Mycom skids each consist of an oil injected screw compressor of 750 SCFM capacity with a 350 hp motor, oil pump, oil cooler, and oil separator. Helium gas returning from the heat exchanger train is compressed from 1 atm to 20 atm in the compressor. The compressed gas is then passed through the three coalescer de-mister where oil mist is separated from the helium gas. The helium gas then flows through the charcoal adsorber and molecular sieve where any residual oil vapor and water vapor are removed. The final stage of purification is the final filter which removes any remaining particulates from the compressed helium gas. The end product of this system is compressed and purified helium gas ready to be cooled down to cryogenic temperatures

  2. Experimental investigation of a thermoacoustic-Stirling refrigerator driven by a thermoacoustic-Stirling heat engine.

    Science.gov (United States)

    Luo, E C; Dai, W; Zhang, Y; Ling, H

    2006-12-22

    In this paper, a thermally-driven thermoacoustic refrigerator system without any moving part is reported. This refrigeration system consists of a thermoacoustic-Stirling heat engine and a thermoacoustic-Stirling refrigerator; that is, the former is the driving source for the latter. Both the subsystems are designed to operate on traveling-wave mode. In the experiment, it was found that the DC-flows had significant negative effect on the heat engine and the refrigerator. To suppress these DC-flows, two flexible membranes were inserted into the two subsystems and worked very well. Then extensive experiments were made to test the influence of different parameters on refrigeration performance of the whole system. The system has so far achieved a no-load temperature of -65 degrees C, a cooling capacity of about 270 W at -20 degrees C and 405 W at 0 degrees C; in fact, the result showed a good prospect of the refrigeration system in room-temperature cooling such as food refrigeration and air-conditioning.

  3. Fermilab satellite refrigerator compressors with the oil- and moisture-removal systems

    International Nuclear Information System (INIS)

    Satti, J.A.; Andrews, R.A.

    1983-08-01

    We have designed and tested a helium purification system for the Energy Doubler and the experimental areas. A purification system is installed after each screw compressor in the satellite refrigerators. The purification system removes oil mist, oil vapor, water vapor, and particulate from the compressed helium. The units were designed with consideration of modularity and necessary redundancy (i.e., guard purification). Test results which led to the final configuration are presented, along with achieved performance of the oil removal in the operating system

  4. Quantum Stirling heat engine and refrigerator with single and coupled spin systems

    Science.gov (United States)

    Huang, Xiao-Li; Niu, Xin-Ya; Xiu, Xiao-Ming; Yi, Xue-Xi

    2014-02-01

    We study the reversible quantum Stirling cycle with a single spin or two coupled spins as the working substance. With the single spin as the working substance, we find that under certain conditions the reversed cycle of a heat engine is NOT a refrigerator, this feature holds true for a Stirling heat engine with an ion trapped in a shallow potential as its working substance. The efficiency of quantum Stirling heat engine can be higher than the efficiency of the Carnot engine, but the performance coefficient of the quantum Stirling refrigerator is always lower than its classical counterpart. With two coupled spins as the working substance, we find that a heat engine can turn to a refrigerator due to the increasing of the coupling constant, this can be explained by the properties of the isothermal line in the magnetic field-entropy plane.

  5. Brownian micro-engines and refrigerators in a spatially periodic temperature field: Heat flow and performances

    International Nuclear Information System (INIS)

    Ai Baoquan; Wang Liqiu; Liu Lianggang

    2006-01-01

    We study the thermodynamic features of a thermal motor driven by temperature differences, which consists of a Brownian particle moving in a sawtooth potential with an external load. The motor can work as a heat engine or a refrigerator under different conditions. The heat flow driven by both potential and kinetic energy is considered. The former is reversible when the engine works quasistatically and the latter is always irreversible. The efficiency of the heat engine (Coefficient Of Performance (COP) of a refrigerator) can never approach Carnot efficiency (COP)

  6. Numerical investigation of boiling heat transfer on hydrocarbon mixture refrigerant in vertical rectangular minichannel

    OpenAIRE

    Huixing Li; Yu Liu

    2016-01-01

    In order to investigate the characteristics of boiling heat transfer for hydrocarbon mixture refrigerant in plate-fin heat exchanger which is used in the petrochemical industry field, a model was established on boiling heat transfer in vertical rectangular channel. The simulated results were compared with the experimental data from literature. The results show that the deviation between the simulated results and experimental data is within ±15%. Meanwhile, the characteristic of boiling heat t...

  7. Investigations of Heat Recovery in Different Refrigeration System Solutions in Supermarkets. Effsys2 project final report

    Energy Technology Data Exchange (ETDEWEB)

    Sawalha, Same; Chen, Yang

    2010-07-01

    Supermarkets are intensive energy consumers with constantly increasing number of installations. About 50 % of the energy consumption in the supermarket is absorbed by the refrigeration system to cover the cooling demands. Simultaneously, heating is needed in the supermarket where the rejected heat from the refrigeration system is usually higher than the needs. It is an interesting possibility to utilize the rejected heat from the refrigeration system to cover the heating needs in supermarkets. The objective of this project is to investigate the heat recovery performance of the new refrigeration system solutions in supermarket applications. The focus is on environmentally friendly systems with natural working fluids, mainly CO{sub 2} trans-critical systems. The project analyzes the temperature levels and capacities of rejected heat from different system solutions and investigates its matching with the heating needs in supermarkets. Using simulation tools this project also aims at defining the system solution/s which has good energy efficiency for simultaneous cooling and heat recovery.

  8. Energy and exergy analysis of a double effect absorption refrigeration system based on different heat sources

    International Nuclear Information System (INIS)

    Kaynakli, Omer; Saka, Kenan; Kaynakli, Faruk

    2015-01-01

    Highlights: • Energy and exergy analysis was performed on double effect series flow absorption refrigeration system. • The refrigeration system runs on various heat sources such as hot water, hot air and steam. • A comparative analysis was carried out on these heat sources in terms of exergy destruction and mass flow rate of heat source. • The effect of heat sources on the exergy destruction of high pressure generator was investigated. - Abstract: Absorption refrigeration systems are environmental friendly since they can utilize industrial waste heat and/or solar energy. In terms of heat source of the systems, researchers prefer one type heat source usually such as hot water or steam. Some studies can be free from environment. In this study, energy and exergy analysis is performed on a double effect series flow absorption refrigeration system with water/lithium bromide as working fluid pair. The refrigeration system runs on various heat sources such as hot water, hot air and steam via High Pressure Generator (HPG) because of hot water/steam and hot air are the most common available heat source for absorption applications but the first law of thermodynamics may not be sufficient analyze the absorption refrigeration system and to show the difference of utilize for different type heat source. On the other hand operation temperatures of the overall system and its components have a major effect on their performance and functionality. In this regard, a parametric study conducted here to investigate this effect on heat capacity and exergy destruction of the HPG, coefficient of performance (COP) of the system, and mass flow rate of heat sources. Also, a comparative analysis is carried out on several heat sources (e.g. hot water, hot air and steam) in terms of exergy destruction and mass flow rate of heat source. From the analyses it is observed that exergy destruction of the HPG increases at higher temperature of the heat sources, condenser and absorber, and lower

  9. Exergy analysis of heating, refrigerating and air conditioning methods and applications

    CERN Document Server

    Dincer, Ibrahim

    2015-01-01

    Improve and optimize efficiency of HVAC and related energy systems from an exergy perspective. From fundamentals to advanced applications, Exergy Analysis of Heating, Air Conditioning, and Refrigeration provides readers with a clear and concise description of exergy analysis and its many uses. Focusing on the application of exergy methods to the primary technologies for heating, refrigerating, and air conditioning, Ibrahim Dincer and Marc A. Rosen demonstrate exactly how exergy can help improve and optimize efficiency, environmental performance, and cost-effectiveness. The book also discusses the analysis tools available, and includes many comprehensive case studies on current and emerging systems and technologies for real-world examples. From introducing exergy and thermodynamic fundamentals to presenting the use of exergy methods for heating, refrigeration, and air conditioning systems, this book equips any researcher or practicing engineer with the tools needed to learn and master the application of exergy...

  10. Flow boiling heat transfer coefficients at cryogenic temperatures for multi-component refrigerant mixtures of nitrogen-hydrocarbons

    Science.gov (United States)

    Ardhapurkar, P. M.; Sridharan, Arunkumar; Atrey, M. D.

    2014-01-01

    The recuperative heat exchanger governs the overall performance of the mixed refrigerant Joule-Thomson cryocooler. In these heat exchangers, the non-azeotropic refrigerant mixture of nitrogen-hydrocarbons undergoes boiling and condensation simultaneously at cryogenic temperature. Hence, the design of such heat exchanger is crucial. However, due to lack of empirical correlations to predict two-phase heat transfer coefficients of multi-component mixtures at low temperature, the design of such heat exchanger is difficult.

  11. A Comparative Cycle and Refrigerant Simulation Procedure Applied on Air-Water Heat Pumps

    DEFF Research Database (Denmark)

    Mader, Gunda; Palm, Björn; Elmegaard, Brian

    2012-01-01

    A vapor compression heat pump absorbs heat from the environment at a low temperature level and rejects heat at a high temperature level. The bigger the difference between the two temperature levels the more challenging is it to gain high energy efficiency with a basic cycle layout as found in most...... small capacity heat pump applications today. Many of the applicable refrigerants also reach their technical limits regarding low vapor pressure for very low source temperatures and high discharge temperatures for high sink temperatures. These issues are especially manifest for air-water heat pumps. Many...... alternative cycle setups and refrigerants are known to improve the energy efficiency of a vapor compression cycle and reduce discharge temperatures. However not all of them are feasible for small capacity heat pumps from a cost and complexity point of view. This paper presents a novel numerical approach...

  12. Thermo-economic optimization of an endoreversible four-heat-reservoir absorption-refrigerator

    International Nuclear Information System (INIS)

    Qin Xiaoyong; Chen Lingen; Sun Fengrui; Wu Chih

    2005-01-01

    Based on an endoreversible four-heat-reservoir absorption-refrigeration-cycle model, the optimal thermo-economic performance of an absorption-refrigerator is analyzed and optimized assuming a linear (Newtonian) heat-transfer law applies. The optimal relation between the thermo-economic criterion and the coefficient of performance (COP), the maximum thermo-economic criterion, and the COP and specific cooling load for the maximum thermo-economic criterion of the cycle are derived using finite-time thermodynamics. Moreover, the effects of the cycle parameters on the thermo-economic performance of the cycle are studied by numerical examples

  13. A compact dilution refrigerator with vertical heat exchangers for operation to 2 mK

    International Nuclear Information System (INIS)

    Bunkov, Yu.M.; Guenault, A.M.; Hayward, D.J.; Jackson, D.A.; Kennedy, C.J.; Nichols, T.R.; Miller, I.E.; Pickett, G.R.; Ward, M.G.

    1991-01-01

    A compactly designed dilution refrigerator with closely packed, vertical heat exchangers is described. The refrigerator reaches a temperature of 2 mK and is easily constructed, since the sintered heat exchangers are straight units. Vibrating wire resonators are employed in the mixing chamber as diagnostic tools, which may act as both thermometers and phase-boundary level indicators. There is a design problem in the vertical arrangement, namely, the sumps on the concentrated phase side that can slowly fill with dilute phase and degrade the performance. The problem is solved by draining the superfluid 4 He component in any collected dilute phase through superleaks into the mixing chamber

  14. Experimental Results For Hydrocarbon Refrigerant Vaporization In Brazed Plate Heat Exchangers at High Pressure

    OpenAIRE

    Desideri, Adriano; Schmidt Ommen, Torben; Wronski, Jorrit; Quoilin, Sylvain; Lemort, Vincent; Haglind, Fredrik

    2016-01-01

    In this contribution, the experimental heat transfer coefficient  and the pressure drop measured during HFC refrigerants vaporization inside small brazed plate heat exchanger (PHE) at typical evaporation temperature for organic Rankine cycle systems for low thermal energy quality applications are presented. Scientific work focusing on the heat transfer in PHEs has been carried out since the late 19th century. More recent publications have been focusing on vaporization and condensation of ref...

  15. Refrigerant falling film evaporation review: Description, fluid dynamics and heat transfer

    International Nuclear Information System (INIS)

    Fernández-Seara, José; Pardiñas, Ángel Á.

    2014-01-01

    Falling film horizontal tube evaporators for refrigeration equipment are an interesting alternative to pool boiling evaporators concerning operation costs, safety, thermodynamic efficiency, charge of refrigerant or size. Plenty of literature works studied falling film evaporation, but for its application in fields such as desalination and petrochemical industry or OTEC. This review focuses mainly on those works from the literature that analysed the main issues of falling film evaporation of refrigerants, to better understand heat transfer and fluid dynamics in such evaporators. First, falling film evaporation is described and compared to pool boiling, to define its main advantages and inconveniences. Then, the literature concerning film around the tubes and between them is analysed, as well as the phenomenon of film breakdown, which sharply deteriorates the heat transfer performance of falling film evaporators. After it, the results from those works that studied analytically and experimentally the heat transfer coefficients (HTCs) with different types of tubes and refrigerants are discussed. The review finishes with a brief summary of important parameters of falling film evaporation, which might be useful for the design of such equipment. - Highlights: •We defined falling film evaporation and compared it with pool boiling. •We reviewed works from the literature concerning refrigerant falling film evaporation. •We classified the ideas from the works attending to crucial aspects of the process. •We developed a summary of the main ideas which could be useful for design purpose

  16. From Consumption to Prosumption - Operational Cost Optimization for Refrigeration System With Heat Waste Recovery

    DEFF Research Database (Denmark)

    Minko, Tomasz; Garcia, Jesus Lago; Bendtsen, Jan Dimon

    2017-01-01

    Implementation of liquid cooling transforms a refrigeration system into a combined cooling and heating system. Reclaimed heat can be used for building heating purposes or can be sold. Carbon dioxide based refrigeration systems are considered to have a particularly high potential for becoming ecient...... heat energy producers. In this paper a CO2 system that operates in the subcritical region is examined. Modelling approach is presented, and used for operation optimisation by way of non-linear model predictive control techniques. Assuming that the heat is sold when using both objective functions......, it turns out that the system have negative operational cost. In case when Cost Minimization objective function is used daily revenue is about 7:9 [eur], for Prosumption one it is 11:9 [eur]....

  17. The effect of heat exchanger parameters on performance predictions for nonazeotropic refrigerant mixtures in liquid-liquid heat pumps

    International Nuclear Information System (INIS)

    Stanger, S.; Den Braven, K.R.; Owre, T.A.S.

    1990-01-01

    The effects of constant heat exchanger area on the coefficient of performance (COP) for liquid-liquid heat pumps were analyzed for systems which use nonazeotropic mixtures as the working fluid. For this analysis, two different computer models were compared. In the first, the log mean temperature differences (LMTDs) through the heat exchangers were specified, and were held constant for all refrigerant compositions. The second method was constructed so that the heat exchanger UA product was held constant, thus approximating constant heat exchanger area over a range of refrigerant compositions. Results from these models show only a one percent difference in COP prediction between holding LMTD constant and holding UA constant over the range of mixture composition. This paper reports the models compared using mixtures of R-22/R-11 and R-22/R-114. It is also shown that changes in glide and lift temperatures have little influence on the differences between the two models

  18. Solar driven air conditioning and refrigeration systems corresponding to various heating source temperatures

    International Nuclear Information System (INIS)

    Wang, R.Z.; Xu, Z.Y.; Pan, Q.W.; Du, S.; Xia, Z.Z.

    2016-01-01

    Highlights: • Modular silica gel–water adsorption chiller was designed and tested. • Single/double effect LiBr–water absorption chiller was operated and tested. • 1.n effect LiBr–water absorption chiller was proposed, designed and tested. • CaCl_2/AC–ammonia adsorption refrigerator was introduced and tested. • NH_3–H_2O absorption ice maker with better internal heat recovery was introduced. - Abstract: Solar driven air conditioning systems can cope with solar collectors working in a wide range of temperatures. Sorption systems, including absorption and adsorption refrigeration systems, are among the best choices for solar cooling. Five systems including modular silica gel–water adsorption chiller, single/double effect LiBr–water absorption chiller, 1.n effect LiBr–water absorption chiller, CaCl_2/AC (activated carbon)–ammonia adsorption refrigerator, and the water–ammonia absorption ice maker with better internal heat recovery were presented. The above five sorption chillers/refrigerators work under various driven temperatures and fulfill different refrigeration demands. The thermodynamic design and system development of the systems were shown. All these systems have improvements in comparison with existing systems and may offer good options for high efficient solar cooling in the near future.

  19. TRANSIENT AND STEADY STATE STUDY OF PURE AND MIXED REFRIGERANTS IN A RESIDENTIAL HEAT PUMP

    Science.gov (United States)

    The report gives results of an experimental and theoretical investigation of the transient and steady state performance of a residential air-conditioning/heat pump (AC/HP) operating with different refrigerants. (NOTE: The project was motivated by environmental concerns related to...

  20. Efficiencies and coefficients of performance of heat engines, refrigerators, and heat pumps with friction: a universal limiting behavior.

    Science.gov (United States)

    Bizarro, João P S; Rodrigues, Paulo

    2012-11-01

    For work-producing heat engines, or work-consuming refrigerators and heat pumps, the percentage decrease caused by friction in their efficiencies, or coefficients of performance (COP's), is approximately given by the ratio W(fric)/W between the work spent against friction forces and the work performed by, or delivered to, the working fluid. This universal scaling, which applies in the limit of small friction (W(fric)/W heat-engine efficiencies), allows a simple and quick estimate of the impact that friction losses can have on the FOM's of thermal engines and plants, or of the level of those losses from the observed and predicted FOM's. In the case of refrigerators and heat pumps, if W(fric)/W heat engines), the COP percentage decrease due to friction approaches asymptotically (W(fric)/W)/(1+W(fric)/W) instead of W(fric)/W. Estimates for the level of frictional losses using the Carnot (or, for heat engines and power plants only, the Curzon-Ahlborn) predictions and observed FOM's of real power plants, heat engines, refrigerators, and heat pumps show that they usually operate in domains where these behaviors are valid.

  1. Utilization of process energy from supermarket refrigeration systems. Coupling of cooling and heating; Prozessenergienutzung von Supermarktkaelteanlagen. Kaelte-Waerme-Kopplung

    Energy Technology Data Exchange (ETDEWEB)

    Wirsching, Alexander [TEKO Gesellschaft fuer Kaeltetechnik mbH, Altenstadt (Germany). Technologie und Kommunikation

    2010-03-15

    The efficiency is defined as the relation between utility and expenditure. Thus, it is obvious for the specialist of refrigeration to tackle with the expenditure (energy consumption) since the utilization conventionally is defined as the produced/need cooling performance of a refrigeration plant. If refrigeration plants are regarded according to their function (withdrawal of heat from a refrigeration chamber and delivery to the environment), the heating system is the producer of the requirement for cooling in 'the winter' (heating season). Thus, the refrigeration plant perhaps already has a marvellous efficiency, and the separate heating system too - however in interaction. The broad view moves into the focus. The possible approaches and effects are described in the contribution under consideration using the example of a Discount supermarket with a sales area of 800 square meters and a requirement of cooling of more than 30 kW.

  2. Refrigeration. Heat Transfer. Part I: Evaporators and Condensers

    DEFF Research Database (Denmark)

    Knudsen, Hans-Jørgen Høgaard

    2002-01-01

    The note gives an introduction to heat transfer with phase shift. Pool Boiling, Flow Boiling, Condensation.......The note gives an introduction to heat transfer with phase shift. Pool Boiling, Flow Boiling, Condensation....

  3. Two-phase Flow Ejector as Water Refrigerant by Using Waste Heat

    International Nuclear Information System (INIS)

    Yamanaka, H; Nakagawa, M

    2013-01-01

    Energy saving and the use of clean energy sources have recently become significant issues. It is expected that clean energy sources such as solar panels and fuel cells will be installed in many private dwellings. However, when electrical power is generated, exhaust heat is simultaneously produced. Especially for the summer season, the development of refrigeration systems that can use this waste heat is highly desirable. One approach is an ejector that can reduce the mechanical compression work required in a normal refrigeration cycle. We focus on the use of water as a refrigerant, since this can be safely implemented in private dwellings. Although the energy conversion efficiency is low, it is promising because it can use heat that would otherwise be discarded. However, a steam ejector refrigeration cycle requires a large amount of energy to change saturated water into vapour. Thus, we propose a more efficient two-phase flow ejector cycle. Experiments were carried out in which the quality of the two-phase flow from a tank was varied, and the efficiency of the ejector and nozzle was determined. The results show that a vacuum state can be achieved and suction exerted with a two-phase flow state at the ejector nozzle inlet.

  4. Market Assessment for Residential Refrigerator-Freezer with Novel Rotating Heat Exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Sikes, Karen [CSRA International, Inc., Fairfax, VA (United States); Blackburn, Julia [CSRA International, Inc., Fairfax, VA (United States); Grubbs, Tyler [CSRA International, Inc., Fairfax, VA (United States); Abdelaziz, Omar [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Momen, Ayyoub [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-02-01

    Despite a steady record of energy efficiency improvements in residential refrigerators and freezers over recent decades, these products still account for 4% of the site energy consumption for the average U.S. household. The Oak Ridge National Laboratory (ORNL) – along with partners Sandia National Laboratories (SNL) and the University of Maryland – are pursuing further efficiency improvements in this market sector by using a novel/prototype rotating heat exchanger (RHX) based on a Sandia Cooler technology as an evaporator in a residential refrigerator-freezer. The purpose of this study is to investigate the market potential of refrigerator-freezer products equipped with RHX evaporators in the United States, including projections of maximum annual market share and unit shipments and maximum direct and indirect job creation.

  5. Heat transfer correlations for evaporation of refrigerant mixtures flowing inside horizontal microfin tubes

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaoyan [School of Energy Engineering, Xi' an University of Science and Technology, 58 Yanta Street, Xi' an, Shaanxi 710054 (China); School of Energy and Power Engineering, Xi' an Jiaotong University, 28 Xianning Road, Xi' an, Shaanxi 710049 (China); Yuan, Xiuling [School of Energy and Power Engineering, Xi' an Jiaotong University, 28 Xianning Road, Xi' an, Shaanxi 710049 (China)

    2008-11-15

    Based on the experimental results of R417A flowing inside horizontal microfin tubes, the present work deals with the development of prediction methods for evaporation heat transfer of refrigerant mixtures in microfin tube. The microfin model by Thome et al. is modified by adjusting the convective heat transfer term, and the other microfin model is developed by introducing the enhancement factor into the modified-Kattan model. The comparison of the calculations by several microfin models and the experimental results reveals that the new microfin models developed at the present study are in much better agreement with the experimental results with the reducing average deviation by 30-50% than the models by Thome et al. and Cavallini et al., and are recommended for the prediction of evaporation heat transfer coefficients for non-azeotropic refrigerant mixtures inside microfin tubes. (author)

  6. Heat transfer correlations for evaporation of refrigerant mixtures flowing inside horizontal microfin tubes

    Energy Technology Data Exchange (ETDEWEB)

    Xiaoyan, Zhang [School of Energy Engineering, Xi' an University of Science and Technology, 58 Yanta Street, Xi' an, Shaanxi 710054 (China); School of Energy and Power Engineering, Xi' an Jiaotong University, 28 Xianning Road, Xi' an, Shaanxi 710049 (China)], E-mail: gqzxy@sohu.com; Xiuling, Yuan [School of Energy and Power Engineering, Xi' an Jiaotong University, 28 Xianning Road, Xi' an, Shaanxi 710049 (China)

    2008-11-15

    Based on the experimental results of R417A flowing inside horizontal microfin tubes, the present work deals with the development of prediction methods for evaporation heat transfer of refrigerant mixtures in microfin tube. The microfin model by Thome et al. is modified by adjusting the convective heat transfer term, and the other microfin model is developed by introducing the enhancement factor into the modified-Kattan model. The comparison of the calculations by several microfin models and the experimental results reveals that the new microfin models developed at the present study are in much better agreement with the experimental results with the reducing average deviation by 30-50% than the models by Thome et al. and Cavallini et al., and are recommended for the prediction of evaporation heat transfer coefficients for non-azeotropic refrigerant mixtures inside microfin tubes.

  7. Heat transfer correlations for evaporation of refrigerant mixtures flowing inside horizontal microfin tubes

    International Nuclear Information System (INIS)

    Zhang Xiaoyan; Yuan Xiuling

    2008-01-01

    Based on the experimental results of R417A flowing inside horizontal microfin tubes, the present work deals with the development of prediction methods for evaporation heat transfer of refrigerant mixtures in microfin tube. The microfin model by Thome et al. is modified by adjusting the convective heat transfer term, and the other microfin model is developed by introducing the enhancement factor into the modified-Kattan model. The comparison of the calculations by several microfin models and the experimental results reveals that the new microfin models developed at the present study are in much better agreement with the experimental results with the reducing average deviation by 30-50% than the models by Thome et al. and Cavallini et al., and are recommended for the prediction of evaporation heat transfer coefficients for non-azeotropic refrigerant mixtures inside microfin tubes

  8. Condensation heat transfer for refrigerant-oil mixtures in microfin tube condenser

    Energy Technology Data Exchange (ETDEWEB)

    Cho, K N [Sungkyunkwan University, Seoul (Korea); Tae, S J [Sungkyunkwan University Graduate School, Seoul (Korea)

    2000-04-01

    Condensation heat transfer experiments for R-22 and R-407 C refrigerants mixed with mineral oil and POE oil respectively were performed in straight and U-bend sections of a microfin tube. Experimental parameters were an oil concentration from 0 to 5 %, a mass flux from 100 to 400 kg/m{sup 2}s and an inlet quality from 0.5 to 0.9. The enhancement factors for R-22 and R-407 C refrigerants at the first straight section decreased continuously as the oil concentration increased. They decreased rapidly as the mass maximum at the 90 deg. position. The heat transfer coefficients at the second straight section within the dimensionless length of 48 were larger by a maximum of 33 % than the average heat transfer coefficients at the first straight section. (author). 10 refs., 6 figs., 1 tab.

  9. Refrigerant charge, pressure drop, and condensation heat transfer in flattened tubes

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, M J; Newell, T A; Chato, J C [University of Illinois, Urbana, IL (United States). Dept. of Mechanical and Industrial Engineering; Infante Ferreira, C A [Delft University of Technology (Netherlands). Laboratory for Refrigeration and Indoor Climate Control

    2003-06-01

    Horizontal smooth and microfinned copper tubes with an approximate diameter of 9 mm were successively flattened in order to determine changes in flow field characteristics as a round tube is altered into a flattened tube profile. Refrigerants R134a and R410A were investigated over a mass flux range from 75 to 400 kg m{sup -2} s{sup -}2{sup 1} and a quality range from approximately 10-80%. For a given refrigerant mass flow rate, the results show that a significant reduction in refrigerant charge is possible. Pressure drop results show increases of pressure drop at a given mass flux and quality as a tube profile is flattened. Heat transfer results indicate enhancement of the condensation heat transfer coefficient as a tube is flattened. Flattened tubes with an 18{sup o} helix angle displayed the highest heat transfer coefficients. Smooth tubes and axial microfin tubes displayed similar levels of heat transfer enhancement. Heat transfer enhancement is dependent on the mass flux, quality and tube profile. (author)

  10. Experimental study on an innovative multifunction heat pipe type heat recovery two-stage sorption refrigeration system

    International Nuclear Information System (INIS)

    Li, T.X.; Wang, R.Z.; Wang, L.W.; Lu, Z.S.

    2008-01-01

    An innovative multifunction heat pipe type sorption refrigeration system is designed, in which a two-stage sorption thermodynamic cycle based on two heat recovery processes was employed to reduce the driving heat source temperature, and the composite sorbent of CaCl 2 and activated carbon was used to improve the mass and heat transfer performances. For this test unit, the heating, cooling and heat recovery processes between two reactive beds are performed by multifunction heat pipes. The aim of this paper is to investigate the cycled characteristics of two-stage sorption refrigeration system with heat recovery processes. The two sub-cycles of a two-stage cycle have different sorption platforms though the adsorption and desorption temperatures are equivalent. The experimental results showed that the pressure evolutions of two beds are nearly equivalent during the first stage, and desorption pressure during the second stage is large higher than that in the first stage while the desorption temperatures are same during the two operation stages. In comparison with conventional two-stage cycle, the two-stage cycle with heat recovery processes can reduce the heating load for desorber and cooling load for adsorber, the coefficient of performance (COP) has been improved more than 23% when both cycles have the same regeneration temperature of 103 deg. C and the cooling water temperature of 30 deg. C. The advanced two-stage cycle provides an effective method for application of sorption refrigeration technology under the condition of low-grade temperature heat source or utilization of renewable energy

  11. Heat and mass transfer prediction of binary refrigerant mixtures condensing in a horizontal microfin tube

    Energy Technology Data Exchange (ETDEWEB)

    Koyama, Shigeru; Yu, Jian; Ishibashi, Akira

    1999-07-01

    In the face of the phase-out of HCFC22 for its effect on globe environment, the alternative refrigerant has been paid attention in the refrigeration and heat pump industry. In the present stage, it is found that any pure refrigerant is not a good substitute of HCFC22 for the system in use. The authors have to use binary or ternary refrigerant mixtures as the substitute to meet industrial requirement. But until now, although the heat transfer characteristics of the refrigerant mixtures can be measured in experiments and predicted in some degree, the mass transfer characteristics in condensation process, which is a main part in most systems, can not be clarified by both experimental and theoretical methods. In the present study a non-equilibrium model for condensation of binary refrigerant mixtures inside a horizontal microfin tube is proposed. In this model it is assumed that the phase equilibrium is only established at the vapor-liquid interface, while the bulk vapor and the bulk liquid are in non-equilibrium in the same cross section. The mass transfer characteristic in vapor core is obtained from the analogy between mass and momentum transfer. In the liquid layer, the mass fraction distribution is neglected, but the mass transfer coefficient is treated as infinite that can keep a finite value for the mass transfer rate in liquid phase. From the calculation results compared with the experimental ones for the condensation of HFC134a/HCFC123 and HCFC22/CFC114 mixtures, it is found that the calculated heat flux distribution along the tube axis is in good agreement with that of experiment, and the calculated values of condensing length agree well with the experimental ones. Using the present model, the local mass faction distribution, the diffusion mass transfer rate and the mass transfer characteristics in both vapor and liquid phase are demonstrated. From these results, the effect of mass transfer resistance on condensation heat transfer characteristics for binary

  12. High Effectiveness Heat Exchanger for Cryogenic Refrigerators, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose an innovative high performance cryogenic heat exchanger manufactured of titanium by photo-etching and diffusion bonding. This is a parallel plate design...

  13. Theoretical study of heat pump system using CO2/dimethylether as refrigerant

    Directory of Open Access Journals (Sweden)

    Fan Xiao-Wei

    2013-01-01

    Full Text Available Nowadays, HCFC22 is widely used in heat pump systems in China, which should be phased out in the future. Thus, eco-friendly mixture CO2/dimethylether is proposed to replace HCFC22. Compared with pure CO2 and pure dimethylether, the mixture can reduce the heat rejection pressure, and suppress the flammability and explosivity of pure dimethylether. According to the Chinese National Standards on heat pump water heater and space heating system, performances of the subcritical heat pump system are discussed and compared with those of the HCFC22 system. It can be concluded that CO2 /dimethylether mixture works efficiently as a refrigerant for heat pumps with a large heat-sink temperature rise. When mass fraction of dimethylether is increased, the heat rejection pressure is reduced. Under the nominal working condition, there is an optimal mixture mass fraction of 28/72 of CO2/dimethylether for water heater application under conventional condensation pressure, 3/97 for space heating application. For water heater application, both the heating coefficient of performance and volumetric heating capacity increase by 17.90% and 2.74%, respectively, compared with those of HCFC22 systems. For space heating application, the heating coefficient of performance increases by 8.44% while volumetric heating capacity decreases by 34.76%, compared with those of HCFC22 systems. As the superheat degree increases, both the heating coefficient of performance and volumetric heating capacity tend to decrease.

  14. Numerical Study of Compact Plate-Fin Heat Exchanger for Rotary-Vane Gas Refrigeration Machine

    Directory of Open Access Journals (Sweden)

    V. V. Trandafilov

    2017-10-01

    Full Text Available Plate-fin heat exchangers are widely used in refrigeration technique. They are popular because of their compactness and excellent heat transfer performance. Here we present a numerical model for the development, research and optimization of a plate-fin heat exchanger for a rotary-vane gas refrigeration machine. The method of analysis by graphic method of plate - fin heat exchanger is proposed. The model describes the effects of secondary parameters such as axial thermal conductivity through a metal matrix of the heat exchanger. The influence of geometric parameters and heat transfer coefficient is studied. Graphs of dependences of length, efficiency of a fin and pressure drop in a heat exchanger on the thickness of the fin and the number of fins per meter are obtained. To analyze the results of numerical simulation, the heat exchanger was designed in the Aspen HYSYS program. The simulation results show that the total deviation from the proposed numerical model is not more than 15%. 

  15. Heat transfer property of refrigerant-oil mixture in a flooded evaporator: The role of bubble formation and oil retention

    International Nuclear Information System (INIS)

    Koo, Kyoung-Min; Kim, Sung-Gyu; Jeong, Young-Man; Lee, Jae-Keun; Kim, Soo Hyung; Lee, Soowon; Park, Nae-Hyun; Na, Byung-Chul; Hwang, Yoon-Jae; Kim, Byung-Soon; Hwang, Joon-Hyun

    2013-01-01

    We examined the effect of oil retention on the heat transfer performance of a shell-and-tube-type evaporator which had 26 inner tubes and was filled with the refrigerant R-134a. The refrigerant was boiled on the surface of the inner tubes in the evaporator, while chilled water circulated through these tubes. An experimental apparatus was designed to measure both the pressure and temperature profiles at the inlet and outlet of the flooded evaporator. Four windows were installed for observing the operation of the flooded evaporator. A series of experiments were carried out under the following conditions: the refrigerant saturation temperature, 5 .deg. C; refrigerant inlet quality, 0.1; heat fluxes from water to the refrigerant, 5-7 kW/m"2.. The concentration of the oil retained in the refrigerant was then varied up to approximately 10% to observe the effect on the heat transfer performance of the flooded evaporator. Increasing the oil content (i.e., increasing the concentration up to a maximum of approximately 10%) in the refrigerant R134a did not lead to any appreciable reduction in the overall heat transfer coefficient of a flooded evaporator with multiple-inner-tubes. When the oil concentration in the refrigerant was approximately 10%, the heat transfer degradation in the case of the flooded evaporator with multiple-inner-tubes was approximately 11%, which was found to be much smaller than the heat transfer degradation in the case of a flooded evaporator with a single-tube (26-49%). This observation suggested that the oil retained in the refrigerant did not significantly deteriorate the heat transfer performance of the flooded evaporator, presumably because the presence of tube bundles promoted forced convection by agitating bubbles

  16. Using waste heat of ship as energy source for an absorption refrigeration system

    International Nuclear Information System (INIS)

    Salmi, Waltteri; Vanttola, Juha; Elg, Mia; Kuosa, Maunu; Lahdelma, Risto

    2017-01-01

    Highlights: • A steady-state thermodynamic model is developed for absorption refrigeration in a ship. • Operation profile of B.Delta37 bulk carrier is used as an initial data. • Suitability of water-LiBr and ammonia-water working pairs were validated. • Coefficient of performance (COP) was studied in ISO and tropical conditions. • Estimated energy savings were 47 and 95 tons of fuel every year. - Abstract: This work presents a steady-state thermodynamic model for absorption refrigeration cycles with water-LiBr and ammonia-water working pairs for purpose of application on a ship. The coefficient of performance was studied with different generator and evaporator temperatures in ISO and tropical conditions. Absorption refrigeration systems were examined using exhaust gases, jacket water, and scavenge air as energy sources. Optimal generator temperatures for different refrigerant temperatures were found using different waste heat sources and for the absorption cycle itself. Critical temperature values (where the refrigeration power drops to zero) were defined. All of these values were used in order to evaluate the cooling power and energy production possibilities in a bulk carrier. The process data of exhaust gases and cooling water flows in two different climate conditions (ISO and tropical) and operation profiles of a B. Delta37 bulk carrier were used as initial data in the study. With the case ship data, a theoretical potential of saving of 70% of the electricity used in accommodation (AC use) compressor in ISO conditions and 61% in tropical conditions was recognized. Those estimates enable between 47 and 95 tons of annual fuel savings, respectively. Moreover, jacket water heat recovery with a water-LiBr system has the potential to provide 2.2–4.0 times more cooling power than required during sea-time operations in ISO conditions, depending on the main engine load.

  17. Heating, Ventilation, Air Conditioning, and Refrigeration (HVAC/R), AFSC 3E1X1. OSSN 2368

    National Research Council Canada - National Science Library

    1999-01-01

    Survey Coverage: The Heating, Ventilation, Air Conditioning, and Refrigeration (HVAC/R) career ladder, AFSC 3E1X1, was surveyed to gather data needed to guide the development and evaluation of training...

  18. The steady-state modeling and optimization of a refrigeration system for high heat flux removal

    International Nuclear Information System (INIS)

    Zhou Rongliang; Zhang Tiejun; Catano, Juan; Wen, John T.; Michna, Gregory J.; Peles, Yoav; Jensen, Michael K.

    2010-01-01

    Steady-state modeling and optimization of a refrigeration system for high heat flux removal, such as electronics cooling, is studied. The refrigeration cycle proposed consists of multiple evaporators, liquid accumulator, compressor, condenser and expansion valves. To obtain more efficient heat transfer and higher critical heat flux (CHF), the evaporators operate with two-phase flow only. This unique operating condition necessitates the inclusion of a liquid accumulator with integrated heater for the safe operation of the compressor. Due to the projected incorporation of microchannels into the system to enhance the heat transfer in heat sinks, the momentum balance equation, rarely seen in previous vapor compression cycle heat exchangers modeling efforts, is utilized in addition to the mass and energy balance equations to capture the expected significant microchannel pressure drop witnessed in previous experimental investigations. Using the steady-state model developed, a parametric study is performed to study the effect of various external inputs on the system performance. The Pareto optimization is applied to find the optimal system operating conditions for given heat loads such that the system coefficient of performance (COP) is optimized while satisfying the CHF and other system operation constraints. Initial validation efforts show the good agreement between the experimental data and model predictions.

  19. Effect of refrigeration lubricants on the heat transfer performance in the microfin tube evaporator

    Energy Technology Data Exchange (ETDEWEB)

    Cho, K N; Tae, S J [Sung Kyun Kwan University, Seoul (Korea)

    1999-01-01

    The present study experimentally investigated the defect of refrigeration lubricant on the heat transfer performance in the straight sections and U-bend of a microfin tube evaporator by using R-22/mineral oil and R-407C/POE oil. The apparatus consisted of test section with U-bend, preheater, condenser, oil injection and sampling devices, magnetic pump, mass flow meter etc. The experimental parameters were oil concentration of 0 to 5 wt%, inlet quality of 0.1 to 0.5, mass flux of 219 and 400 kg/m{sup 2}s and heat flux of 10 and 20 kw/m{sup 2}. The effects of parameters on the heat transfer coefficients were large in the order of inlet quality, mass flux and heat flux as oil concentration got increased. As oil concentration was increased, heat transfer coefficients were continuously decreased for R-22 and increased by 3% up to the concentration of 1% and then decreased for R-407C under the condition of large inlet quality, and small mass flux and heat flux. But, the heat transfer coefficients were increased up to the opposite conditions. The variation of enhancement factors for R-407C refrigerants under the opposite conditions. The variation of enhancement factors for R-407C was under 50% of that for R-22 and the variation with respect to the positions in the test section was small. The pressure drops were increased for both R-22 and R-407C refrigerants as oil concentration was increased. The pressure drops for R-407C were smaller by the maximum of 18% than those for R-22. 12 refs., 1 tab., 14 figs.

  20. Condensation heat transfer coefficients of flammable refrigerants on various enhanced tubes

    International Nuclear Information System (INIS)

    Park, Ki Jung; Jung, Dong Soo

    2005-01-01

    In this study, external condensation Heat Transfer Coefficients (HTCs) of six flammable refrigerants of propylene (R1270), propane (R290), isobutane (R600a), butane (R600), dimethylether (RE170), and HFC32 were measured at the vapor temperature of 39 .deg. C on a 1023 fpm low fin and turbo-C tubes. All data were taken under the heat flux of 32∼116 and 42∼142 kW/m 2 for the low fin and turbo-C tubes respectively. Flammable refrigerants' data obtained on enhanced tubes showed a typical trend that external condensation HTCs decrease with increasing wall subcooling. HFC32 and DME showed up to 30% higher HTCs than those of HCFC22 due to their excellent thermophysical properties. Propylene, propane, isobutane, and butane showed similar or lower HTCs than those of HCFC22. Beatty and Katz' correlation predicted the HTCs of the flammable refrigerants obtained on a low fin tube within a mean deviation of 7.3%. Turbo-C tube showed the best performance due to its 3 dimensional surface geometry for fast removal of condensate

  1. Heat-machine control by quantum-state preparation: from quantum engines to refrigerators.

    Science.gov (United States)

    Gelbwaser-Klimovsky, D; Kurizki, G

    2014-08-01

    We explore the dependence of the performance bounds of heat engines and refrigerators on the initial quantum state and the subsequent evolution of their piston, modeled by a quantized harmonic oscillator. Our goal is to provide a fully quantized treatment of self-contained (autonomous) heat machines, as opposed to their prevailing semiclassical description that consists of a quantum system alternately coupled to a hot or a cold heat bath and parametrically driven by a classical time-dependent piston or field. Here, by contrast, there is no external time-dependent driving. Instead, the evolution is caused by the stationary simultaneous interaction of two heat baths (having distinct spectra and temperatures) with a single two-level system that is in turn coupled to the quantum piston. The fully quantized treatment we put forward allows us to investigate work extraction and refrigeration by the tools of quantum-optical amplifier and dissipation theory, particularly, by the analysis of amplified or dissipated phase-plane quasiprobability distributions. Our main insight is that quantum states may be thermodynamic resources and can provide a powerful handle, or control, on the efficiency of the heat machine. In particular, a piston initialized in a coherent state can cause the engine to produce work at an efficiency above the Carnot bound in the linear amplification regime. In the refrigeration regime, the coefficient of performance can transgress the Carnot bound if the piston is initialized in a Fock state. The piston may be realized by a vibrational mode, as in nanomechanical setups, or an electromagnetic field mode, as in cavity-based scenarios.

  2. A comparative study of different heat exchange systems in a thermoelectric refrigerator and their influence on the efficiency

    International Nuclear Information System (INIS)

    Astrain, D.; Aranguren, P.; Martínez, A.; Rodríguez, A.; Pérez, M.G.

    2016-01-01

    Highlights: • Total efficiency optimisation of a thermoelectric refrigerator. • Experimental study of three different types of heat exchangers for thermoelectrics. • Influence of the occupancy ratio in thermal resistance. • Important decrease in the electric consumption of a thermoelectric refrigerator. - Abstract: Thermoelectric refrigeration (TEC) exhibits several advantages compared to vapour-compression, since this technology presents accurate temperature control systems and higher levels of compactness, robustness and noiselessness. However, its low efficiency is acting as a deterrent for it to spread in the refrigeration market. One of the factors determining the efficiency of a thermoelectric refrigerator is the temperature difference between the hot and cold sides of the thermoelectric modules (TEMs). This is dependent on the thermal resistances of the heat exchangers used. This paper discusses the results of an experimental study of different types of heat exchangers for the thermoelectric module hot side: a water–air system comprising a cold plate, pump and fan coil; a finned heat sink with fan; a heat pipe with fan. Expressions of thermal resistance have been obtained for these three types as a function of the air and water mass flows and the number of TEMs per unit of surface area of heat exchanger (occupancy ratio, δ), as well as expressions of the power consumed by the fans and the pump. Finally, a computational study has been carried out on a thermoelectric refrigerator of 15 m"3 of interior volume, in order to obtain the influence of the heat exchanger studied, on the total consumption of the refrigerator and its efficiency. The results have demonstrated that relevant improvements can be made in TEC efficiency by the proper optimisation of the heat exchangers.

  3. Thermoacoustic refrigeration

    Science.gov (United States)

    Garrett, Steven L.; Hofler, Thomas J.

    1991-12-01

    A new refrigerator which uses resonant high amplitude sound in inert gases to pump heat is described and demonstrated. The phasing of the thermoacoustic cycle is provided by thermal conduction. This 'natural' phasing allows the entire refrigerator to operate with only one moving part (the loudspeaker diaphragm). The thermoacoustic refrigerator has no sliding seals, requires no lubrication, uses only low-tolerance machine parts, and contains no expensive components. Because the compressor moving mass is typically small and the oscillation frequency is high, the small amount of vibration is very easily isolated. This low vibration and lack of sliding seals makes thermoacoustic refrigeration an excellent candidate for food refrigeration and commercial/residential air conditioning applications. The design, fabrication, and performance of the first practical, autonomous thermoacoustic refrigerator, which will be flown on the Space Shuttle (STS-42), are described, and designs for terrestrial applications are presented.

  4. Condensing heat transfer characteristics of hydrocarbon refrigerants in 9.52 and 12.7 mm smooth tube

    Science.gov (United States)

    Yoon, Jung-In; Lee, Ho-Saeng; Lee, Kwang-Bae; Kim, Jae-Dol; Bansal, Pradeep

    2005-12-01

    Experimental results for heat transfer characteristic and pressure gradients of hydrocarbon (HC) refrigerants and R-22 during condensing inside horizontal double pipe heat exchangers are presented. The test sections which have one tube diameter of 12.70 mm with 0.86 mm wall thickness, another tube diameter of 9.52 mm with 0.76 mm wall thickness are used for this investigation. The local condensing heat transfer coefficients of HC refrigerants were higher than that of R-22. The average condensing heat transfer coefficient increased with the increase of the mass flux. It showed the higher values in HC refrigerants than R-22. Comparing the heat transfer coefficient of experimental results with that of other correlations, the presented results had a good agreement with most of the Cavallini’s correlations.

  5. Reducing heat transfer across the insulated walls of refrigerated truck trailers by the application of phase change materials

    International Nuclear Information System (INIS)

    Ahmed, Mashud; Meade, Oliver; Medina, Mario A.

    2010-01-01

    A general estimate shows that 80% of communities across the United States receive their goods exclusively by transport trucks, of which a significant number are climate-controlled because they carry perishable goods, pharmaceutical items and many other temperature-sensitive commodities. Keeping the inside of a truck trailer at a constant temperature and relative humidity requires exact amounts of heat and/or moisture management throughout the shipment period, which is regulated via small refrigeration units, placed outside the truck, that operate by burning fuel. These trucks, known as refrigerated truck trailers, are the focus of this paper. In the research presented herein, the conventional method of insulation of the refrigerated truck trailer was modified using phase change materials (PCMs). The limited research carried out in refrigerated transport compared to other refrigeration processes has left spaces for innovative solutions in this area. The research investigated the inclusion of paraffin-based PCMs in the standard trailer walls as a heat transfer reduction technology. An average reduction in peak heat transfer rate of 29.1% was observed when all walls (south, east, north, west, and top) were considered. For individual walls, the peak heat transfer rate was reduced in the range of 11.3-43.8%. Overall average daily heat flow reductions into the refrigerated compartment of 16.3% were observed. These results could potentially translate into energy savings, pollution abatement from diesel-burning refrigeration units, refrigeration equipment size reduction, and extended equipment operational life. The research and its results will help to better understand the scope of this technology.

  6. A novel absorption refrigeration cycle for heat sources with large temperature change

    International Nuclear Information System (INIS)

    Yan, Xiaona; Chen, Guangming; Hong, Daliang; Lin, Shunrong; Tang, Liming

    2013-01-01

    To increase the use efficiency of available thermal energy in the waste gas/water, a novel high-efficient absorption refrigeration cycle regarded as an improved single-effect/double-lift configuration is proposed. The improved cycle using an evaporator/absorber (E/A) promotes the coefficient of performance and reduces the irreversible loss. Water–lithium bromide is used as the working pair and a simulation study under the steady working conditions is conducted. The results show that the temperature of waste gas discharged is about 20 °C lower than that of the conventional single-effect cycle and the novel cycle we proposed can achieve more cooling capacity per unit mass of waste gas/water at the simulated working conditions. -- Graphical abstract: Pressure – temperature diagram for water – lithium bromide. Highlights: ► A novel waste heat-driven absorption refrigeration cycle is presented. ► The novel cycle can reject heat at much lower temperature. ► The available temperature range of heat source of the proposed cycle is wider. ► Multiple heat sources with different temperatures can be used in the novel cycle

  7. Numerical investigation of boiling heat transfer on hydrocarbon mixture refrigerant in vertical rectangular minichannel

    Directory of Open Access Journals (Sweden)

    Huixing Li

    2016-05-01

    Full Text Available In order to investigate the characteristics of boiling heat transfer for hydrocarbon mixture refrigerant in plate-fin heat exchanger which is used in the petrochemical industry field, a model was established on boiling heat transfer in vertical rectangular channel. The simulated results were compared with the experimental data from literature. The results show that the deviation between the simulated results and experimental data is within ±15%. Meanwhile, the characteristic of boiling heat transfer was investigated in vertical rectangular minichannel of plate-fin heat exchanger. The results show that the boiling heat transfer coefficient increases with the increase in quality and mass flux and is slightly impacted by the heat flux. This is because that the main boiling mechanism is forced convective boiling while the contribution of nucleate boiling is slight. The correlation of Liu and Winterton is in good agreement with the simulation results. The deviation between correlation calculations and simulation results is mostly less than ±15%. These results will provide some constructive instructions for the understanding of saturated boiling mechanism in a vertical rectangular minichannel and the prediction of heat transfer performance in plate-fin heat exchanger.

  8. Experimental and numerical study of heat transfer across insulation wall of a refrigerated integral panel van

    International Nuclear Information System (INIS)

    Glouannec, Patrick; Michel, Benoit; Delamarre, Guillaume; Grohens, Yves

    2014-01-01

    This paper presents an experimental and numerical design study of an insulation wall for refrigerated vans. The thermophysical properties of the insulating multilayer panel, the external environment impact (solar irradiation, temperature, etc.) and durability are taken into account. Different tools are used to characterize the thermal performances of the insulation walls and the thermal properties of the insulation materials are measured. In addition, an experiment at the wall scale is carried out and a 2D FEM model of heat and mass transfer within the wall is formulated. Three configurations are studied with this design approach. Multilayer insulation walls containing reflective multi-foil insulation, aerogel and phase change materials (PCM) are tested. Promising results are obtained with these materials, especially the reduction of peak heat transfer and energy consumption during the daytime period. Furthermore, the major influence of solar irradiation is highlighted as it can increase the peak heat transfer crossing the insulation wall by up to 43%. Nevertheless, we showed that the use of reflective multi-foil insulation and aerogel layers allowed decreasing this impact by 27%. - Highlights: • A design study of an insulation wall for a refrigerated van is carried out. • Experimental and numerical studies of multilayer insulation walls are performed. • The major influence of solar irradiation is highlighted. • New insulation materials (reflective multi-foil, aerogel and PCM) are tested

  9. Thermodynamic analysis of a refrigeration cycle using regenerative heat exchanger - suction/liquid line

    Energy Technology Data Exchange (ETDEWEB)

    Tebchirani, Tarik Linhares; Matos, Rudmar Serafim [Pos graduate Programme in Mechanical Engineering (PGMEC), Universidade Federal do Parana, Curitiba, PR (Brazil)], e-mails: tarik@utfpr.edu.br, rudmar@demec.ufpr.br

    2010-07-01

    This paper presents results from thermodynamic comparison of a conventional compression cycle and a steam cycle that uses a heat exchanger countercurrent (liquid line/suction line) in an air conditioning system split. The main objective is to study the relationship between the COP and the mass variation of refrigerant to the effectiveness of the heat exchanger. The papers presented in the literature discuss the matter in a theoretical way, are summarized in tables of rare loss statements without specification of methods. The methodology of work is based on testing of an air conditioner operating conventionally and also with the heat exchanger for the determination of values and parameters of interest. The tests were performed in a thermal chamber with temperature controlled and equipped with a data acquisition system for reading and storage results. The refrigerant was R22. Besides making possible an assessment of the feasibility of cost-benefit thermodynamics, it is suggested a different method for installing the equipment type split. (author)

  10. A semi-analytical refrigeration cycle modelling approach for a heat pump hot water heater

    Science.gov (United States)

    Panaras, G.; Mathioulakis, E.; Belessiotis, V.

    2018-04-01

    The use of heat pump systems in applications like the production of hot water or space heating makes important the modelling of the processes for the evaluation of the performance of existing systems, as well as for design purposes. The proposed semi-analytical model offers the opportunity to estimate the performance of a heat pump system producing hot water, without using detailed geometrical or any performance data. This is important, as for many commercial systems the type and characteristics of the involved subcomponents can hardly be detected, thus not allowing the implementation of more analytical approaches or the exploitation of the manufacturers' catalogue performance data. The analysis copes with the issues related with the development of the models of the subcomponents involved in the studied system. Issues not discussed thoroughly in the existing literature, as the refrigerant mass inventory in the case an accumulator is present, are examined effectively.

  11. Performance of large-scale helium refrigerators subjected to pulsed heat load from fusion devices

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, R.; Ghosh, P.; Chowdhury, K. [Cryogenic Engineering Centre, Indian Institute of Technology, Kharagpur (India)

    2012-07-01

    The immediate effect of pulsed heat load from fusion devices in helium refrigerators is wide variation in mass flow rate of low pressure stream returning to the cold-box. In this paper, a four expander based modified Claude cycle has been analyzed in quasi steady and dynamic simulations using Aspen HYSYS to identify critical equipment that may be affected due to such flow rate fluctuations at the return stream and their transient performance. Additional constraints on process parameters over steady state design have been identified. Suitable techniques for mitigation of fluctuation of return stream have also been explored. (author)

  12. Performance of large-scale helium refrigerators subjected to pulsed heat load from fusion devices

    International Nuclear Information System (INIS)

    Dutta, R.; Ghosh, P.; Chowdhury, K.

    2012-01-01

    The immediate effect of pulsed heat load from fusion devices in helium refrigerators is wide variation in mass flow rate of low pressure stream returning to the cold-box. In this paper, a four expander based modified Claude cycle has been analyzed in quasi steady and dynamic simulations using Aspen HYSYS to identify critical equipment that may be affected due to such flow rate fluctuations at the return stream and their transient performance. Additional constraints on process parameters over steady state design have been identified. Suitable techniques for mitigation of fluctuation of return stream have also been explored. (author)

  13. PROCESSES OF HEAT-MASS-TRANSFER IN APPARATUS OF SOLAR ABSORBING REFRIGERATION SYSTEMS

    Directory of Open Access Journals (Sweden)

    Doroshenko A.V.

    2014-12-01

    Full Text Available Ideology of development of the solar refrigeration systems and systems of air-conditioning, based on the use of absorbing cycle and solar energy for the regeneration of absorbent solution, is presented in the article. The processes of joint heat-mass-transfer are considered in the direct and indirect types of evaporated coolers taking into account the phenomenon of re-condensation of aquatic steams at the low temperature evaporated cooling of environments. The pre-liminary analysis of possibilities of the solar systems is executed as it applies in relation to the tasks of cooling of envi-ronments and air-conditioning systems.

  14. Experimental Study on Compression/Absorption High-Temperature Hybrid Heat Pump with Natural Refrigerant Mixture

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ji Young; Park, Seong Ryong; Baik, Young Jin; Chang, Ki Chang; Ra, Ho Sang; Kim, Min Sung [Korea Institute of Energy Research, Daejeon (Korea, Republic of); Kim, Yong Chan [Korea University, Seoul (Korea, Republic of)

    2011-12-15

    This research concerns the development of a compression/absorption high-temperature hybrid heat pump that uses a natural refrigerant mixture. Heat pumps based on the compression/absorption cycle offer various advantages over conventional heat pumps based on the vapor compression cycle, such as large temperature glide, temperature lift, flexible operating range, and capacity control. In this study, a lab-scale prototype hybrid heat pump was constructed with a two-stage compressor, absorber, desorber, desuperheater, solution heat exchanger, solution pump, liquid/vapor separator, and rectifier as the main components. The hybrid heat pump system operated at 10-kW-class heating capacity producing hot water whose temperature was more than 90 .deg. C when the heat source and sink temperatures were 50 .deg. C. Experiments with various NH{sub 3}/H{sub 2}O mass fractions and compressor/pump circulation ratios were performed on the system. From the study, the system performance was optimized at a specific NH{sub 3} concentration.

  15. Heat flux anomalies in Antarctica revealed from satellite magnetic data

    DEFF Research Database (Denmark)

    Maule, Cathrine Fox; Purucker, Michael E.; Olsen, Nils

    2005-01-01

    a method that uses satellite magnetic data to estimate the heat flux underneath the Antarctic ice sheet. We found that the heat flux underneath the ice sheet varies from 40 to 185 megawatts per square meter and that areas of high heat flux coincide with known current volcanism and some areas known to have...

  16. Identification of critical equipment and determination of operational limits in helium refrigerators under pulsed heat load

    Science.gov (United States)

    Dutta, Rohan; Ghosh, Parthasarathi; Chowdhury, Kanchan

    2014-01-01

    Large-scale helium refrigerators are subjected to pulsed heat load from tokamaks. As these plants are designed for constant heat loads, operation under such varying load may lead to instability in plants thereby tripping the operation of different equipment. To understand the behavior of the plant subjected to pulsed heat load, an existing plant of 120 W at 4.2 K and another large-scale plant of 18 kW at 4.2 K have been analyzed using a commercial process simulator Aspen Hysys®. A similar heat load characteristic has been applied in both quasi steady state and dynamic analysis to determine critical stages and equipment of these plants from operational point of view. It has been found that the coldest part of both the cycles consisting JT-stage and its preceding reverse Brayton stage are the most affected stages of the cycles. Further analysis of the above stages and constituting equipment revealed limits of operation with respect to variation of return stream flow rate resulted from such heat load variations. The observations on the outcome of the analysis can be used for devising techniques for steady operation of the plants subjected to pulsed heat load.

  17. A Correlation for Forced Convective Boiling Heat Transfer of Refrigerants in a Microfin Tube

    Science.gov (United States)

    Momoki, Satoru; Yu, Jian; Koyama, Shigeru; Fujii, Tetsu; Honda, Hiroshi

    The experimental study is reported on the forced convective boiling of pure refrigerants HCFC22, HFC134a and HCFC123 flowing in a horizontal microfin tube. The local heat transfer coefficient defined based on the actual inside surface area is measured in the ranges of mass velocity of 200 to 400 kg/m2s, heat flux of 5 to 64 kW/m2 and reduced pressure of 0.07 to 0.24. Using the Chen-type model, a new correlation for microfin tubes is proposed considering the enhancement effect of microfins on both the convective heat transfer and the nucleate boiling components. In the convective heat transfer component, the correlation to predict the heat transfer coefficient of liquid-only flow is determined from preliminary experiments on single-phase flow in microfin tubes, and the two-phase flow enhancement factor is determined from the present experimental data. For the nucleate boiling component, the correlation of Takamatsu et al. for smooth tube is modified. The prediction of the present correlation agrees well with present experimental data, and is available for several microfin tubes which were tested by other researchers.

  18. Effect of multi-stream heat exchanger on performance of natural gas liquefaction with mixed refrigerant

    Science.gov (United States)

    Chang, Ho-Myung; Lim, Hye Su; Choe, Kun Hyung

    2012-12-01

    A thermodynamic study is carried out to investigate the effect of multi-stream heat exchanger on the performance of natural gas (NG) liquefaction with mixed refrigerant (MR). A cold stream (low-pressure MR) is in thermal contact with opposite flow of two hot streams (high-pressure MR and NG feed) at the same time. In typical process simulation with commercial software (such as Aspen HYSYS®), the liquefaction performance is estimated with a method of minimum temperature approach, simply assuming that two hot streams have the same temperature. In this study, local energy balance equations are rigorously solved with temperature-dependent properties of MR and NG feed, and are linked to the thermodynamic cycle analysis. The figure of merit (FOM) is quantitatively examined in terms of UA (the product of overall heat transfer coefficient and heat exchange area) between respective streams. In a single-stage MR process, it is concluded that the temperature profile from HYSYS is difficult to realize in practice, and the FOM value from HYSYS is an over-estimate, but can be closely achieved with a proper heat-exchanger design. It is also demonstrated that there exists a unique optimal ratio in three UA's, and no direct heat exchanger between hot streams is recommended.

  19. Effects of air flow maldistribution on refrigeration system dynamics of air source heat pump chiller under frosting conditions

    International Nuclear Information System (INIS)

    Gong Jianying; Gao Tieyu; Yuan Xiuling; Huang Dong

    2008-01-01

    The effects of air flow maldistribution on the performance of an air source heat pump chiller under frosting conditions were investigated experimentally. The results indicated that air flow maldistribution was the dominant factor leading to hunting of the thermostatic expansion valve for medium and/or large size finned tube evaporators. With air flow maldistribution degree (AMD) increasing, frost occurred earlier, and the frost layer grew faster. The operating characteristics became lower when AMD was increased. We found such phenomenon seemed to be related to both the difference of refrigerant outlet superheat and the frosting velocity. In the hunting stage, the frost block effect became the main factor degrading the refrigeration system performance. With AMD increasing, the heat pump system pertinent performance data (suction pressure, evaporation temperature, discharge pressure, refrigerant outlet temperature, etc.) were degraded more dramatically

  20. Evaluation of thermal-hydraulic performance of hydrocarbon refrigerants during flow boiling in a microchannels array heat sink

    International Nuclear Information System (INIS)

    Chávez, Cristian A.; Leão, Hugo L.S.L.; Ribatski, Gherhardt

    2017-01-01

    Highlights: • Evaluation of refrigerants R600a, R290 and R1270 during flow boiling in a microchannels array. • Comparison of data for hydrocarbons with previous data for R134a. • Parametric analysis of heat transfer coefficient, pressure drop, ONB and exergy behaviors. • Comparison of the experimental data and prediction methods from literature. • In general, refrigerant R290 presents the best performance. - Abstract: The present study concerns an experimental evaluation of the performance of hydrocarbon refrigerants during flow boiling in a microchannels array heat sink. The heat sink is composed of fifty channels with cross sectional areas of 123 × 494 μm"2 and length of 15 mm manufactured in a copper block. Heat transfer coefficient and pressure drop data were obtained for refrigerants R600a, R290 and R1270, mass velocities from 165 to 823 kg/m"2 s, heat fluxes up to 400 kW/m"2, liquid subcooling at the inlet of the test section of 5, 10 and 15 °C and saturation temperature of 25 °C. The data were compared with experimental results obtained in a previous study for R134a and predictions by methods from literature. In general, R290 presented the best performance, providing the highest average heat transfer coefficient and a pressure drop only slightly higher than R1270 that was the fluid presenting the lowest pressure drop. An exergy analysis also revealed the refrigerant R290 as the one presenting the best performance. However, R290 needed the highest excess of superheating to trigger the boiling process (ONB). The methods from literature evaluated in the present study poorly predicted the experimental data for two-phase pressure drop. On the other hand, the method of Kanizawa et al. (2016) was quite accurate in predicting the heat transfer results.

  1. Alternative refrigerants performance in plate heat condenser for air conditioning; Scambiatori compatti per il condizionamento ambientale

    Energy Technology Data Exchange (ETDEWEB)

    Boccardi, G.; Celata, G.P.; Marchesi Donati, F. [ENEA, Rome (Italy). Inst. of Thermal-Fluid Dynamics; Cumo, M. [Rome Univ. La Sapienza, Rome (Italy). Dept. of Nuclear Engineering and Energy Conversion; Gerosa, A. [Rome Univ. Tor Vergata, Rome (Italy). Dept. of Mechanical Engineering; Zorzin, A. [R and D Alfa Laval Artec Spa Vicenza, Vicenza (Italy)

    1999-12-01

    An experimental campaign on plate heat exchangers, used as evaporators and condenser in domestic refrigeration loops is presented in this paper. The research's purpose is to test the influence of some thermal-hydraulic parameters on the global overall heat transfer coefficient. R134a, R407C, R410A, and R22 are the fluids tested under reference thermal conditions. The experimental tests allows one to withdraw conclusions on the substitution effect on the thermal and global efficiency of the plant. Also, a new method for calculating the thermodynamical mixture parameters is applied to the condensation of mixtures R407C and R410A and its benefit evaluated. The refrigerant loop overall performance and the condenser global heat transfer coefficient are the parameters chosen to enlighten the characteristics of the alternative refrigerants (R134a, R407C, and R410A) with respect to the fluid that they are supposed to substitute (R22). [Italian] Scambiatori a piastre compatti impiegati come evaporatori e condensatori nei circuiti frigoriferi, sono l'oggetto della ricerca presentata in questo articolo. L'efficienza termica di tali componenti e' valutata in condizioni di riferimento commerciali. I refrigeranti utilizzati sono tre fluidi proposti per sostituire l'R22, un Hcfc, attualmente il refrigerante piu' utilizzato nel condizionamento ambientale. Una serie di prove condotte con quest'ultimo fluido consente di studiare gli effetti della sostituzione del fluido di progetto sulle prestazioni sia degli scambiatori, sia piu' in generale, dell'intero circuito frigorifero. In particolare sono state studiate le prestazioni di due coppie di evaporatori e condensatori in termini di coefficiente globale di scambio termico e di Cop dell'impianto. Nel presente lavoro e' inoltre presentato e utilizzato un metodo termodinamico per il calcolo della temperatura di saturazione per le miscele zeotropiche in bifase; uno dei refrigeranti

  2. Contribution to the heat transfer analysis of substitute refrigerants in evaporator tubes with smooth or enhanced tube surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kattan, N

    1997-12-31

    The substitution of CFC refrigerants in refrigeration systems, heat pumps and organic Rankine cycles for heat recovery, requests a good knowledge of heat transfer properties of substitute fluids. A new test facility has been built at the Laboratory for Industrial Energy Systems (LENI) to contribute to this international effort. It consists of two sets of concentric tubes allowing either annular or inside tube convective boiling with a counter current water flow heating to be studied. A new data base including heat transfer coefficients and pressure drop measurements for four new refrigerants (R123, R134A, R402A and R404A) and three older refrigerants (R11, R12 and R502) has been collected. Flow boiling measurements covered a broad range of mass velocities, vapor qualities and heat fluxes. Some of the tests included plain tubes and others enhanced surface tubes (microfilms from Wieland) in horizontal and vertical orientations. An improved Wilson plot technique, that covers both the transition and turbulent flow regimes of the water flowing in the annular channel for the inside tube boiling tests, is proposed to overcome the severe limitations of conventional Wilson plots, to improve accuracy and to facilitate data processing. Mean flow boiling heat transfer coefficients were measured for R12 and R134A evaporating inside a horizontal plain tube and for R11 and R123 evaporating inside a horizontal plain tube. Local flow boiling heat transfer coefficients were measured for : R134A, R123, R404A and R502 evaporating inside a horizontal plain tube, for R134A and R123 evaporating inside a horizontal microfin tube and for R134 evaporating inside a vertical microfin tube. In addition microfin heat transfer augmentation relative to plain tube test data was investigated. The measured heat transfer coefficients were compared to different existing inside tube flow boiling correlations. (author) figs., tabs., refs.

  3. Cooling, freezing and heating with the air cycle: air as the ultimate green refrigerant

    NARCIS (Netherlands)

    Verschoor, M.J.E.

    2000-01-01

    Due to the recent concern about the damage that CFCs cause to the environment (ozone layer, global warming) and the absence of commonly acceptable alternative refrigerants, the search for alternative refrigeration concepts is going on. Air as refrigerant in the Joule-Brayton cycle (air cycle) is one

  4. Experimental study on a prototype of heat pipe solar water heater using refrigerant R134a as a transfer fluid

    Science.gov (United States)

    Sitepu, T.; Sembiring, J.; Ambarita, H.

    2018-02-01

    A prototype of a solar water heater by using refrigerant as a heat transfer fluid is investigated experimentally. The objective is to explore the characteristics and the performance of the prototype. To make heat transfer from the collector to the heated fluid effectively, refrigerant R134a is used as a transfer. In the experiments, the initial pressure inside the heat pipe is varied. The prototype is exposed to solar irradiation in a location in Medan city for three days of the experiment. Solar collector temperatures, solar radiation, water temperature, and ambient temperature are measured. The efficiency of the system is analyzed. The results show that temperature of the hot water increases as the initial pressure of the working fluid increase. However, the increasing is not linear, and there must exist an optimum initial pressure. For the case with the refrigerant pressure of 110 psi, the maximum hot water temperature and maximum thermal efficiency are 45.36oC and 53.23%, respectively. The main conclusion can be drawn here is that solar water heater by using refrigerant R134a should be operated at initial pressure 110 psi.

  5. Articulated, Performance-Based Instruction Objectives Guide for Air Conditioning, Refrigeration, and Heating. Volume II (Second Year).

    Science.gov (United States)

    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…

  6. Thermodynamic optimization of mixed refrigerant Joule- Thomson systems constrained by heat transfer considerations

    International Nuclear Information System (INIS)

    Hinze, J F; Klein, S A; Nellis, G F

    2015-01-01

    Mixed refrigerant (MR) working fluids can significantly increase the cooling capacity of a Joule-Thomson (JT) cycle. The optimization of MRJT systems has been the subject of substantial research. However, most optimization techniques do not model the recuperator in sufficient detail. For example, the recuperator is usually assumed to have a heat transfer coefficient that does not vary with the mixture. Ongoing work at the University of Wisconsin-Madison has shown that the heat transfer coefficients for two-phase flow are approximately three times greater than for a single phase mixture when the mixture quality is between 15% and 85%. As a result, a system that optimizes a MR without also requiring that the flow be in this quality range may require an extremely large recuperator or not achieve the performance predicted by the model. To ensure optimal performance of the JT cycle, the MR should be selected such that it is entirely two-phase within the recuperator. To determine the optimal MR composition, a parametric study was conducted assuming a thermodynamically ideal cycle. The results of the parametric study are graphically presented on a contour plot in the parameter space consisting of the extremes of the qualities that exist within the recuperator. The contours show constant values of the normalized refrigeration power. This ‘map’ shows the effect of MR composition on the cycle performance and it can be used to select the MR that provides a high cooling load while also constraining the recuperator to be two phase. The predicted best MR composition can be used as a starting point for experimentally determining the best MR. (paper)

  7. Experimental investigation of moderately high temperature water source heat pump with non-azeotropic refrigerant mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Shengjun; Wang, Huaixin; Guo, Tao [Department of Thermal Energy and Refrigeration Engineering, School of Mechanical Engineering, Tianjin University, Tianjin 300072 (China)

    2010-05-15

    Experimental investigations were carried out on non-azeotropic refrigerant mixtures, named M1A (mass fraction of 20%R152a and 80%R245fa), M1B (mass fraction of 37% R152a and 63%R245fa) and M1C (mass fraction of 50%R152a and 50%R245fa), based on a water-to-water heat pump system in the condensing temperature range of 70-90 C with a cycle temperature lift of 45 C. Performance of R245fa was tested for comparison. Unfair factors in experimental comparative evaluation research with the same apparatus were identified and corrected. Experimental cycle performance of the mixtures were tested and compared with improved experimental assessment methodology. The results show that all of the mixtures deliver higher discharge temperature, higher heating capacity, higher COP and higher {epsilon}{sub h,c} than R245fa. M1B presents the most excellent cycle performance and is recommended as working fluid for moderate/high temperature heat pump. (author)

  8. Effects of synthetic oil in a compression refrigeration system using R410A. Part II: quality of heat transfer and pressure losses within the heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Lottin, O.; Guillemet, P. [Ecole Polytechnique de l' Universite de Nantes (France). Laboratoire de Thermocinetique; Lebreton, J-M. [Electricite de France, Moret sur Loing (France)

    2003-11-01

    The consequences of the oil rejected by the compressor of a vapour-compression refrigeration system on the operation of the evaporator and condenser are analysed. The modelled prototype uses the mixture of HFC R410A and a synthetic polyolester (POE) oil. The rise of the amount of lubricant circulating in the system leads to a progressive change in the behaviour of the mixture of refrigerant and oil that, for the higher oil mass fraction, evolves like a zeotropic mixture. One also observes that the presence of lubricant is generally associated with a fall of the performances of the heat exchangers, except however in the evaporator where an optimum is observed when the quantity of oil is equal to 0.1% of the total mass of the mixture. Some conclusions are drawn about the choice of correlations for the calculation of the refrigerant side heat transfer coefficient in a plate evaporator. (author)

  9. Exergy analysis of single effect absorption refrigeration systems: The heat exchange aspect

    International Nuclear Information System (INIS)

    Joybari, Mahmood Mastani; Haghighat, Fariborz

    2016-01-01

    Highlights: • Exergy analysis of LiBr/H 2 O absorption systems with identical COP was carried out. • Exergy destruction rank: absorber followed by generator, condenser and evaporator. • Lower heat source and chilled water inlet temperature reduced exergy destruction. • Higher cooling water inlet temperature reduced exergy destruction. • Lower HTF mass flow rate increased exergy efficiency even for fixed system COP. - Abstract: The main limitation of conventional energy analysis for the thermal performance of energy systems is that this approach does not consider the quality of energy. On the other hand, exergy analysis not only provides information about the systems performance, but also it can specify the locations and magnitudes of losses. A number of studies investigated the effect of parameters such as the component temperature, and heat transfer fluid (HTF) temperature and mass flow rate on the exergetic performance of the same absorption refrigeration system; thus, reported different coefficient of performance (COP) values. However, in this study, the system COP was considered to remain constant during the investigation. This means comparing systems with different heat exchanger designs (based on HTF mass flow rate and temperature) having the same COP value. The effect of HTF mass flow rate and inlet temperature of the cooling water, chilled water and heat source on the outlet specific exergy and exergy destruction rate of each component was investigated. It was found that the lower HTF mass flow rate decreased exergy destruction of the corresponding component. Moreover, the lower temperature of heat source and chilled water inlet increased the system exergetic efficiency. That was also the case for the higher cooling water inlet temperature. Based on the analysis, since the absorber and condenser accounted for a large portion of the total exergy destruction, cooling tower modification with lower cooling water mass flow rate is recommended

  10. A dilution refrigerator combining low base temperature, high cooling power and low heat leak for use with nuclear cooling

    International Nuclear Information System (INIS)

    Bradley, D.I.; Guenault, A.M.; Keith, V.; Miller, I.E.; Pickett, G.R.; Bradshaw, T.W.; Locke-Scobie, B.G.

    1982-01-01

    The design philosophy, design, construction and performance of a dilution refrigerator specifically intended for nuclear cooling experiments in the submillikelvin regime is described. Attention has been paid from the outset to minimizing sources of heat leaks, and to achieving a low base temperature and relatively high cooling power below 10 mK. The refrigerator uses sintered silver heat exchangers similar to those developed at Grenoble. The machine has a base temperature of 3 mK or lower and can precool a copper nuclear specimen in 6.8 T to 8 mK in 70 h. The heat leak to the innermost nuclear stage is < 30 pW after only a few days' running. (author)

  11. Experimental study of R134a/R410A cascade cycle for variable refrigerant flow heat pump systems

    International Nuclear Information System (INIS)

    Kim, Jeong Hun; Lee, Jae Wan; Park, Warn Gyu; Choi, Hwan Jong; Lee, Sang Hun; Oh, Sai Kee

    2015-01-01

    Cascade cycle is widely applied to heat pumps operating at low ambient temperature to overcome problems such as low heating capacity and Coefficient of performance (COP) deterioration A number of researches have been conducted on cascade cycle heat pumps, but most of those studies were focused on system optimization to determine optimal intermediate temperature in air-to-water heat pumps. However, experimental optimization in regard to air and water heating simultaneously using a cascade cycle has been an understudied area. Therefore, we focused on experimental analysis for a cascade system with Variable refrigerant flow (VRF) heat pumps. Experiments were conducted under a variety of operating conditions, such as ambient and water inlet temperature. COP increased up to 16% when water inlet temperature decreased. COP of VRF heat pumps with cascade cycle is three-times higher compared with conventional boilers as well as 17% higher compared to single heat pumps

  12. Evaporation heat transfer characteristics inside the U-bend of the smooth and the microfin tube using alternative refrigerant

    Energy Technology Data Exchange (ETDEWEB)

    Cho, K N [Sung Kyun Kwan University, Seoul (Korea, Republic of); Kim, B G [Sung Kyun Kwan University Graduate School, Seoul (Korea, Republic of)

    1997-09-01

    The present work experimentally investigated the effects of mass flux, heat flux, inlet quality on the heat transfer performance inside the U-bend of smooth and microfin tube using R-22 and R-407C refrigerants. The parameters were 200 and 400 kg/m{sup 2} s for mass flux, 6 and 12 kw/m{sup 2} for heat flux, 0.1 and 0.2 for inlet quality under the pressure of 0.65 MPa. The apparatus consisted of the test section of four straight sections and three U-bends, preheater, condenser, refrigerant pump, mass flow meter etc. The average heat transfer coefficient at the downstream straight section after U-bend was affected by U-bend due to the centrifugal force and mixing of two-phase flow in the U-bend. The average heat transfer coefficient at the U-bend was 4{approx}33 % higher than that at the straight section. The average heat transfer coefficients were affected in the order of mass flux, heat flux and inlet quality. The average heat transfer coefficients in the microfin tube were lager by 19{approx}49 % and 33{approx}69 % than that in the smooth tube at the straight section and at the U-bend separately. The average heat transfer coefficients for R-407C were larger by 33{approx}41 % and 17{approx}29% than that for R-22 in the smooth tube and the microfin tube separately. (author). 24 refs., 9 figs.

  13. Experimental analysis on frosting characteristic of SK-type finned refrigerating heat exchanger with large-diameter circular holes

    International Nuclear Information System (INIS)

    Fang, Zhao-song; Wang, Hou-hua; Zhang, Jie; Wu, Wei-wei

    2014-01-01

    This paper presents the construction of both a plane fin-and-tube heat exchanger and a SK-type fin-and-tube heat exchanger. Based on plane fin-and-tube heat exchanger, comparative industrial prototype experiments of SK-type fin-and-tube heat exchanger energy efficiency performance were carried out in the artificial climate chamber. Test results confirmed several findings: when the amount of the refrigerant charged is the same and face velocity u = 3.75 m s −1 , SK-type fin-and-tube heat exchanger refrigeration capacity increases by an average of 9.13%; energy consumption reduces by an average of 11.25%, coefficient of performance (COP) of heat exchanger increases by an average of 22.65% with continuous operation during the first 2 h. Also, when the operation time exceeds 2 h, the COP of both types of heat exchangers are both less than 0.6, illustrating that under frost conditions, the defrost interval should not be too long, otherwise energy consumption may sharply spike. - Highlights: •The large holes of SK-type induced the generation of turbulence flow. •The refrigeration capacity and COP of SK-type exceeds that of plane one. •The SK-type fin-and-tube heat exchanger is a new kind of heat transfer equipment. •The defrost interval should not exceed 2 h under frost conditions

  14. Turbulence Heating ObserveR – satellite mission proposal

    Czech Academy of Sciences Publication Activity Database

    Vaivads, A.; Retinò, A.; Souček, Jan; Khotyaintsev, Y. V.; Valentini, F.; Escoubet, C. P.; Alexandrova, O.; André, M.; Bale, S. D.; Balikhin, M.; Burgess, D.; Camporeale, E.; Caprioli, D.; Chen, C. H. K.; Clacey, E.; Cully, C. M.; Keyser de, J.; Eastwood, J. P.; Fazakerley, A. N.; Eriksson, S.; Goldstein, M. L.; Graham, D. B.; Haaland, S.; Hoshino, M.; Ji, H.; Karimabadi, H.; Kucharek, H.; Lavraud, B.; Marcucci, F.; Matthaeus, W. H.; Moore, T. E.; Nakamura, R.; Narita, Y.; Němeček, Z.; Norgren, C.; Opgenoorth, H.; Palmroth, M.; Perrone, D.; Pinçon, J.-L.; Rathsman, P.; Rothkaehl, H.; Sahraoui, F.; Servidio, S.; Sorriso-Valvo, L.; Vainio, L.; Vörös, Z.; Wimmer-Schweingruber, R. F.

    2016-01-01

    Roč. 82, č. 5 (2016), 905820501/1-905820501/16 ISSN 0022-3778 Institutional support: RVO:68378289 Keywords : plasma heating * plasma properties * space plasma physics Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.160, year: 2016 https://www.cambridge.org/core/journals/journal-of-plasma-physics/article/div-classtitleturbulence-heating-observer-satellite-mission-proposaldiv/01BB69B09206CE04C48BEDA8F24ED33C/core-reader

  15. Energy efficient skating rink by heat recovery and CO2 refrigerant; Energiezuinige schaatsbaan door warmteterugwinning en CO2-koudedrager

    Energy Technology Data Exchange (ETDEWEB)

    Mooi, R. [IBK Compac, Houten (Netherlands)

    2009-03-15

    In October 2008 a new indoor skating rink was opened in Enschede, Netherlands. The refrigeration plant for this skating rink was designed, delivered and installed by IBK Compac. CO2 was chosen as the secondary refrigerant; CO2 is easily detectable, sustainable and - above all - very energy efficient, since less pumping energy is required and pipes with a smaller diameter can be used. The waste heat of the refrigeration plant is used for the Zamboni (ice resurfacer), for the central heating system and for the unique floor heating system, which is located under the skating rink. [Dutch] In oktober 2008 werd in Enschede de IJsbaan Twente geopend. Het werd een geheel overdekte schaatsbaan, waarvoor IBK Compac de koude-installatie heeft ontworpen, geleverd en geinstalleerd. Gekozen werd voor CO2 als secundaire koudedrager. CO2 is goed detecteerbaar, duurzaam en vooral zeer energie-efficient doordat er minder pompenergie nodig is en er leidingen met een kleinere diameter kunnen worden gebruikt. De restwarmte van de koelinstallatie wordt o.a. benut voor de dweilmachine (Zamboni), voor het cv-blok en voor het unieke vloerverwarmingssysteem dat onder de ijsbaan ligt.

  16. Satellite combined heat and power plants and their legal autonomy

    International Nuclear Information System (INIS)

    Loibl, Helmut

    2014-01-01

    Since the landmark decision by the German Court of Justice concerning the term ''plant'' in the context of biogas plants it should be clear beyond doubt that satellite combined heat and power plants (CHPs) are legally autonomous plants pursuant to Para. 3 No. 1 of the Renewable Energy Law (EEG). What has yet to be finally resolved are the conditions under which satellite CHPs are to be regarded as autonomous. This will be a question of distance on the one hand and of operation autonomy on the other. In the individual case both these factors will have to be assessed from the perspective of an average objective, informed citizen. To the extent that its heat and electricity are being utilised in a meaningful manner, the plant's autonomy will be beyond doubt, at least in operational terms. Regarding the remuneration to be paid for satellite CHPs the only case requiring special consideration is when a CHP falls under the EEG of 2012. In this case Para. 1 Section 1 Sentence 2 EEG provides that the remuneration for the CHP in question is to be calculated as if there was a single overall plant. To the extent that none of the CHPs fall under the EEG of 2012, the ruling remains that there is a separate entitlement to remuneration for each satellite CHP. This also holds in cases where satellite CHPs that were commissioned after 1 January 2012 are relocated. When a satellite CHP is replaced by a new one, the rate and duration of remuneration remain unchanged. However, when a new satellite CHP is added to an existing satellite CHP via a gas collector line it is to be treated according to the decisions of the Federal Court of Justice concerning biogas plant extensions: It falls under the law that applies to the existing CHP and has an entitlement to a new minimum remuneration period, albeit subject to the degression rate provided by the EEG version in question.

  17. Thermoacoustic engines and refrigerators

    Energy Technology Data Exchange (ETDEWEB)

    Swift, G.

    1996-12-31

    This report is a transcript of a practice lecture given in preparation for a review lecture on the operation of thermoacoustic engines and refrigerators. The author begins by a brief review of the thermodynamic principles underlying the operation of thermoacoustic engines and refrigerators. Remember from thermodynamics class that there are two kinds of heat engines, the heat engine or the prime mover which produces work from heat, and the refrigerator or heat pump that uses work to pump heat. The device operates between two thermal reservoirs at temperatures T{sub hot} and T{sub cold}. In the heat engine, heat flows into the device from the reservoir at T{sub hot}, produces work, and delivers waste heat into the reservoir at T{sub cold}. In the refrigerator, work flows into the device, lifting heat Q{sub cold} from reservoir at T{sub cold} and rejecting waste heat into the reservoir at T{sub hot}.

  18. Thermodynamic analysis of a novel exhaust heat-driven non-adiabatic ejection-absorption refrigeration cycle using R290/oil mixture

    International Nuclear Information System (INIS)

    Li, Keqiao; Cai, Dehua; Liu, Yue; Jiang, Jingkai; Sun, Wei; He, Guogeng

    2017-01-01

    Graphical abstract: A novel air-cooled non-adiabatic ejection-absorption refrigeration cycle using R290/refrigeration oil has been thermodynamically analyzed. Influences of the ejector and the non-adiabatic absorber applications on the system performance and other system operation parameters have been investigated. The simulation results will be of great help to the miniaturization and practical application of the air-cooled absorption refrigeration system. - Highlights: • A novel air-cooled non-adiabatic ejection-absorption refrigeration cycle is proposed. • Influences of the ejector and the air-cooled non-adiabatic absorber applications on the system performance are investigated. • Variations of system performance and other system operation parameters are investigated. • R290/refrigeration oil mixture used as working pairs is analyzed. - Abstract: This paper thermodynamically analyzes a novel air-cooled non-adiabatic ejection-absorption refrigeration cycle with R290/oil mixture driven by exhaust heat. An ejector located at the upstream of the non-adiabatic absorber is employed to improve the cycle performance. Variations of COP, circulation ratio and component heat load of the system as a function of generating temperature, pressure ratio, absorption temperature, condensing temperature and evaporating temperature have been investigated in this work. The simulation results show that, compared with the conventional absorption refrigeration cycle, this non-adiabatic ejection-absorption refrigeration cycle has higher absorption efficiency, better performance, wider working condition range and lower total heat load and its COP can reach as high as 0.5297. The implementation of the ejector and the non-adiabatic absorber helps to realize the miniaturization and wider application of the absorption refrigeration system. In addition, R290/oil mixture is a kind of highly potential working pairs for absorption refrigeration.

  19. Internal heat exchange in an ejector-compression solar refrigeration system with R142b

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, Joge I; Estrada, Claudio A; Best, Roberto [Centro de Investigacion en Energia, UNAM, Temixco, Morelos (Mexico); Dorantes Ruben, J [Departamento de Energia, UNAM Azcapotzalco, Mexico, D.F. (Mexico)

    2000-07-01

    One way to use more efficiently the actual energy transfer in the ejector-compression system, is the use of heat exchangers between some of the components. The inclusion of two heat exchangers, preheater and precooler, is considered in a basic ejector-compression refrigeration system with refrigerant 142b. This study accounts for the energy and exergy efficiencies. COP and {epsilon}, according to parameter variations such as ejector efficiency, generation temperature with different superheating, condensation temperature and heat exchangers effectiveness. As known, the most important parameters in ejector-compression system analysis are the entrain-ment ratio U and system efficiencies COP and {epsilon}. The highest system COP and {epsilon}, as the entrainment ratio U, correspond to the highest exchangers effectiveness, highest superheating generator temperatures, highest ejector efficiency and lowest condenser temperature. For the COP and {epsilon} ratios, their maxima correspond to the same independent variables aforementioned for one of the higher superheating generator temperatures. In this case, this result indicates that the exergy efficiency {epsilon} does not contradict the information given by energy efficiency COP. So, to select correctly and optimum design condition, is enough to employ the COP ratio, which maximum value for the data shown corresponds to a superheating generator temperature of about 110 Celsius degrees, that can only be reached by evacuated tubular collectors or CPC solar concentrators. [Spanish] Una forma de usar mas eficientemente la transferencia real de energia en el sistema eyector-compresion es el uso de intercambiadores de calor entre algunos de los componentes. La inclusion de dos intercambiadores de calor precalentador y pre-enfriador se considera en un sistema de refrigeracion eyector-compresion con refrigerante 142b. Este estudio toma en cuenta las eficiencias de energia y exergia, COP y {epsilon}, de acuerdo con las variaciones

  20. Numerical simulation of tubes-in-tube heat exchanger in a mixed refrigerant Joule-Thomson cryocooler

    Science.gov (United States)

    Damle, R. M.; Ardhapurkar, P. M.; Atrey, M. D.

    2017-02-01

    Mixed refrigerant Joule-Thomson (MRJT) cryocoolers can produce cryogenic temperatures with high efficiency and low operating pressures. As compared to the high system pressures of around 150-200 bar with nitrogen, the operational pressures with non-azeotropic mixtures (e.g., nitrogen-hydrocarbons) come down to 10-25 bar. With mixtures, the heat transfer in the recuperative heat exchanger takes place in the two-phase region. The simultaneous boiling and condensation of the cold and hot gas streams lead to higher heat transfer coefficients as compared to single phase heat exchange. The two-phase heat transfer in the recuperative heat exchanger drastically affects the performance of a MRJT cryocooler. In this work, a previously reported numerical model for a simple tube-in-tube heat exchanger is extended to a multi tubes-in-tube heat exchanger with a transient formulation. Additionally, the J-T expansion process is also considered to simulate the cooling process of the heat exchanger from ambient temperature conditions. A tubes-in-tube heat exchanger offers more heat transfer area per unit volume resulting in a compact design. Also, the division of flow in multiple tubes reduces the pressure drop in the heat exchanger. Simulations with different mixtures of nitrogen-hydrocarbons are carried out and the numerical results are compared with the experimental data.

  1. High temperature refrigerator

    International Nuclear Information System (INIS)

    Steyert, W.A. Jr.

    1978-01-01

    A high temperature magnetic refrigerator is described which uses a Stirling-like cycle in which rotating magnetic working material is heated in zero field and adiabatically magnetized, cooled in high field, then adiabatically demagnetized. During this cycle the working material is in heat exchange with a pumped fluid which absorbs heat from a low temperature heat source and deposits heat in a high temperature reservoir. The magnetic refrigeration cycle operates at an efficiency 70% of Carnot

  2. Design and component testing of a low-temperature waste heat driven refrigeration system. Phases I and II. Progress report

    Energy Technology Data Exchange (ETDEWEB)

    Hynek, S.; Borhanian, H.; Krepchin, I.; Walker, D.; Mariano, C.; Fuller, H.; Lee, K.

    1982-03-01

    The design and the component testing of a 20-ton refrigeration system powered by 140/sup 0/F waste heat have been completed. A major advantage of such a system is that essentially all operating power comes from the waste heat with only minor injections of auxiliary power. This Rankine-Rankine system uses R-22 for both power and refrigeration cycles. A single semi-hermetic housing contains the expander, compressor, feed pump, and motor/generator. The integral induction motor/generator acts as a starter, makes up shaft power deficits, absorbs shaft power surpluses, and provides overspeed protection. Experiments determined that 0.0015 in. is the optimum axial clearance for the gerotor R-22 evaporator feed pump to minimize both friction and backleakage, that oil injection to the pump had no effect on either friction or backleage, and that a centrifugal inducer was needed to prevent cavitation under certain operating conditions. Two cylinders of a standard four-cylinder York refrigeration compressor were transformed into expanders to power the remaining two compressor cylinders. Rotary expander valves were used in lieu of conventional poppet valves to lower breathing losses. Testing demonstrated a 75% mechanical efficiency, an 83% isentropic efficiency, and the necessity to support both the rotary valve and the expander wristpins with rolling contact bearings. Fabrication of the 20-ton experimental system is nearing completion and experimental tests are being planned.

  3. A theoretical study on the performances of thermoelectric heat engine and refrigerator with two-dimensional electron reservoirs

    International Nuclear Information System (INIS)

    Luo, Xiaoguang; Long, Kailin; Wang, Jun; Qiu, Teng; He, Jizhou; Liu, Nian

    2014-01-01

    Theoretical thermoelectric nanophysics models of low-dimensional electronic heat engine and refrigerator devices, comprising two-dimensional hot and cold reservoirs and an interconnecting filtered electron transport mechanism have been established. The models were used to numerically simulate and evaluate the thermoelectric performance and energy conversion efficiencies of these low-dimensional devices, based on three different types of electron transport momentum-dependent filters, referred to herein as k x , k y , and k r filters. Assuming the Fermi-Dirac distribution of electrons, expressions for key thermoelectric performance parameters were derived for the resonant transport processes, in which the transmission of electrons has been approximated as a Lorentzian resonance function. Optimizations were carried out and the corresponding optimized design parameters have been determined, including but not limited to the universal theoretical upper bound of the efficiency at maximum power for heat engines, and the maximum coefficient of performance for refrigerators. From the results, it was determined that k r filter delivers the best thermoelectric performance, followed by the k x filter, and then the k y filter. For refrigerators with any one of three filters, an optimum range for the full width at half maximum of the transport resonance was found to be B T.

  4. Effect of heat recovery water heater system on the performance of residential split air conditioner using hydrocarbon refrigerant (HCR22)

    Science.gov (United States)

    Aziz, A.; Thalal; Amri, I.; Herisiswanto; Mainil, A. K.

    2017-09-01

    This This paper presents the performance of residential split air conditioner (RSAC) using hydrocarbon refrigerant (HCR22) as the effect on the use of heat recovery water heater system (HRWHS). In this study, RSAC was modified with addition of dummy condenser (trombone coil type) as heat recovery water heater system (HRWHS). This HRWHS is installed between a compressor and a condenser by absorbing a part of condenser waste heat. The results show that RSAC with HRWHS is adequate to generate hot water with the temperature range about 46.58˚C - 48.81˚C when compared to without HRWHS and the use of dummy condenser does not give significant effect to the split air conditioner performance. When the use of HRWHS, the refrigerant charge has increase about 19.05%, the compressor power consumption has slightly increase about 1.42% where cooling capacity almost the same with slightly different about 0.39%. The condenser heat rejection is lower about 2.68% and the COP has slightly increased about 1.05% when compared to without HRWHS. The use of HRWHS provide free hot water, it means there is energy saving for heating water without negative impact to the system performance of RSAC.

  5. Fermilab tevatron five refrigerator system tests

    International Nuclear Information System (INIS)

    Rode, C.; Ferry, R.; Leiniger, M.; Makara, J.; Misek, J.; Mizicko, D.; Richied, D.; Theilacker, J.

    1982-01-01

    The Fermilab Tevatron refrigeration system is described with the layout illustrated. The compressor control loops, the refrigerator control loops, and magnet control loops (two per refrigerator) are described and each illustrated. The mobile purifier is described. A five refrigerator test is presented, using two compressor buildings, satellite refrigerator concept test and the test current to the writing. The configuration of the five refrigerator test is diagramed

  6. Evaluation report on the development of an advanced refrigerant for compression heat pumps; Asshukushiki heat pump yo shinki reibai kenkyu kaihatsu hyoka hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-03-01

    The research and development were reported on new refrigerants for compression type heat pumps. From 64 kinds of newly composed ether, CF3CF2OCH3 was developed as candidate compound substituting for CFC-11, and CF3CF2CF2OCH3 and (CF3)2CFOCH3 as those substituting for CFC-11. However, COP of the refrigeration has not been optimized. Global warming potentials were obtained by high-accuracy estimate guidelines. The new refrigerants have no chlorine and therefore no effects on the ozonosphere. Global warming effects also satisfied the present allowable values. There was no problem on human body toxicity in the short-term experiment. Costs of commercially production of the candidate compounds were trially calculated from reaction paths and chemical constitution formulae. Assuming that the raw materials are circulating on the market, plant/equipment investment, production volume, and production cost became 5 billion yen, 1000 tons/year, and 3500-6500 yen/kg in 3 persons/shift and 4 shifts, respectively. This is close to the allowable level which is ten times the CFC-12 price, 5000 yen/KG. The new refrigerants are expected to be fully commercialized in consideration of progress of the composition method and improvement of physical properties in the future. 115 refs., 37 figs., 102 tabs.

  7. Evaluation of refrigerating and air-conditioning technologies in heat cascading systems under the carbon dioxide emissions constraint: the proposal of the energy cascade balance table

    International Nuclear Information System (INIS)

    Shimazaki, Yoichi

    2003-01-01

    The aim of this study was to evaluate the refrigerating and air-conditioning technologies in cases of introducing both heat cascading systems and thermal recycling systems in industries located around urban areas. It is necessary to introduce heat cascading systems in the industrial sector in Japan to reduce carbon dioxide emissions. The concept of heat cascading is the multi-stage use of thermal energy by temperature level. This paper introduces three energy policies for introducing the heat cascading systems. The author develops an energy cascade model based on linear programming so as to minimize the total system costs with carbon taxes. Five cases are investigated. Carbon dioxide emission constraints result in the enhancement of heat cascading, where high temperature heat is supplied for process heating while low temperature heat is shifted to refrigeration. It was found that increasing the amount of garbage combustion waste heat could reduce electric power for the turbo compression refrigerator by promoting waste heat driven ammonia absorption refrigerator. In addition, this study proposes an energy cascade balance table with respect to the temperature level

  8. Ideal gas contribution to the isobaric heat capacity of refrigerants: Poling et al.’s polynomial correlation vs DIPPR data

    International Nuclear Information System (INIS)

    Mulero, Angel; Cachadiña, Isidro; Tian, Jianxiang

    2013-01-01

    Highlights: ► The ideal gas contribution to the isobaric heat capacity of 58 refrigerants is calculated. ► Poling et al.’s polynomial correlation on temperature is used. ► Results are compared with DIPPR data and the correlation extended to higher temperatures. ► New coefficients for the correlation are given. ► Mean average percentage deviations with these new coefficients are lower than 1% for 49 refrigerants. -- Abstract: The ideal gas contribution to the isobaric heat capacity of fluids is a temperature dependent property which is commonly modelled as a polynomial expression. In this work, the performance and accuracy of the polynomial correlation proposed by Poling et al. in their well-known book is checked. To this end, the data accepted in the DIPPR database for 58 refrigerants were used. The mean average percentage deviations (MAPDs) obtained in the temperature range considered by Poling et al., usually up to 1000 K, are greater than 1.5% only for six refrigerants. We extended our study to the temperature range in which accepted DIPPR data are available (usually up to 1500 K), finding that only for four refrigerants can the Poling et al. correlation be used in this extended range. New coefficients for the correlation are given for the 58 refrigerants studied which reproduce the accepted DIPPR data. The new MAPD values are then below 1% for 49 refrigerants

  9. Estimation of performance of a J-T refrigerators operating with nitrogen-hydrocarbon mixtures and a coiled tubes-in-tube heat exchanger

    Science.gov (United States)

    Satya Meher, R.; Venkatarathnam, G.

    2018-06-01

    The exergy efficiency of Joule-Thomson (J-T) refrigerators operating with mixtures (MRC systems) strongly depends on the choice of refrigerant mixture and the performance of the heat exchanger used. Helically coiled, multiple tubes-in-tube heat exchangers with an effectiveness of over 96% are widely used in these types of systems. All the current studies focus only on the different heat transfer correlations and the uncertainty in predicting performance of the heat exchanger alone. The main focus of this work is to estimate the uncertainty in cooling capacity when the homogenous model is used by comparing the theoretical and experimental studies. The comparisons have been extended to some two-phase models present in the literature as well. Experiments have been carried out on a J-T refrigerator at a fixed heat load of 10 W with different nitrogen-hydrocarbon mixtures in the evaporator temperature range of 100-120 K. Different heat transfer models have been used to predict the temperature profiles as well as the cooling capacity of the refrigerator. The results show that the homogenous two-phase flow model is probably the most suitable model for rating the cooling capacity of a J-T refrigerator operating with nitrogen-hydrocarbon mixtures.

  10. Cycle performance of alternative refrigerants for domestic air-conditioning system based on a small finned tube heat exchanger

    International Nuclear Information System (INIS)

    Cheng, Song; Wang, Shuangfeng; Liu, Zhongmin

    2014-01-01

    In order to find alternative refrigerants which exhibit both favorable cycle performance and environmental friendliness, R32 and R290 were utilized to contrast to R22 and R410A as substitutes in the present study. The experiments were conducted with a 5 mm finned tube heat exchanger based on the enthalpy method in a small split household air conditioner. The results showed that in nominal cooling conditions, the COP R of R32 and R290 were 26.8% and 20.4% higher than R22, 7.3% and 2.1% higher than R410A. And in nominal heating conditions, the COP HR of R32 and R290 were both 11.0% higher than R22, 5.3% higher than R410A. The systems with R290 and R32 have similar capacities to that with R22 and R410A in heating mode, but a relatively huge difference of capacities in cooling mode. In consideration of charge amount, R290 could be considered as the most superior alternative refrigerant in air conditioners with the small finned tube heat exchanger. - Highlights: •Comparisons are made in the air conditioner system based on 5 mm tube fin heat exchanger. •The R22 system has a similar performance to others in heating mode while a huge difference in cooling mode. •The optimal charge of R290 is reduced with nearly no decline in the capacity and COP. •SLHX is attached to the system of R290 and successfully promote safety and capacity. •Heat loads are taken into account to evaluate the advantages and disadvantages of R290 and R32

  11. Design and Thermodynamic Analysis of a Steam Ejector Refrigeration/Heat Pump System for Naval Surface Ship Applications

    Directory of Open Access Journals (Sweden)

    Cüneyt Ezgi

    2015-12-01

    Full Text Available Naval surface ships should use thermally driven heating and cooling technologies to continue the Navy’s leadership role in protecting the marine environment. Steam ejector refrigeration (SER or steam ejector heat pump (SEHP systems are thermally driven heating and cooling technologies and seem to be a promising technology to reduce emissions for heating and cooling on board naval surface ships. In this study, design and thermodynamic analysis of a seawater cooled SER and SEHP as an HVAC system for a naval surface ship application are presented and compared with those of a current typical naval ship system case, an H2O-LiBr absorption heat pump and a vapour-compression heat pump. The off-design study estimated the coefficient of performances (COPs were 0.29–0.11 for the cooling mode and 1.29–1.11 for the heating mode, depending on the pressure of the exhaust gas boiler at off-design conditions. In the system operating at the exhaust gas boiler pressure of 0.2 MPa, the optimum area ratio obtained was 23.30.

  12. Technical Subtopic 2.1: Modeling Variable Refrigerant Flow Heat Pump and Heat Recovery Equipment in EnergyPlus

    Energy Technology Data Exchange (ETDEWEB)

    Raustad, Richard; Nigusse, Bereket; Domitrovic, Ron

    2013-09-30

    The University of Central Florida/Florida Solar Energy Center, in cooperation with the Electric Power Research Institute and several variable-refrigerant-flow heat pump (VRF HP) manufacturers, provided a detailed computer model for a VRF HP system in the United States Department of Energy's (U.S. DOE) EnergyPlus? building energy simulation tool. Detailed laboratory testing and field demonstrations were performed to measure equipment performance and compare this performance to both the manufacturer's data and that predicted by the use of this new model through computer simulation. The project goal was to investigate the complex interactions of VRF HP systems from an HVAC system perspective, and explore the operational characteristics of this HVAC system type within a laboratory and real world building environment. Detailed laboratory testing of this advanced HVAC system provided invaluable performance information which does not currently exist in the form required for proper analysis and modeling. This information will also be useful for developing and/or supporting test standards for VRF HP systems. Field testing VRF HP systems also provided performance and operational information pertaining to installation, system configuration, and operational controls. Information collected from both laboratory and field tests were then used to create and validate the VRF HP system computer model which, in turn, provides architects, engineers, and building owners the confidence necessary to accurately and reliably perform building energy simulations. This new VRF HP model is available in the current public release version of DOE?s EnergyPlus software and can be used to investigate building energy use in both new and existing building stock. The general laboratory testing did not use the AHRI Standard 1230 test procedure and instead used an approach designed to measure the field installed full-load operating performance. This projects test methodology used the air

  13. Swiss energy research program on heat-pumps, combined heat and power and refrigeration for 2008-2011; Energieforschungsprogramm. Waermepumpen, Waerme-Kraft-Kopplung, Kaelte fuer die Jahre 2008-2011

    Energy Technology Data Exchange (ETDEWEB)

    Kopp, T. [Hochschule fuer Technik HSR, Rapperswil (Switzerland); Eckmanns, A. [Swiss Federal Office of Energy (OFEN), Berne (Switzerland)

    2009-07-15

    This report published by the Swiss Federal Office of Energy (SFOE) takes a look at the research programme on heat-pumps, combined heat and power and refrigeration for the years 2008 - 2011. Work proposed for the years 2008 - 2011 involves the following topics: Improvement of components and the thermodynamic cycles of heat pumps and refrigeration plants as well as the improvements in the efficiency of cogeneration plants and the reduction of emission of pollutants. Also, the overall optimisation of total systems is to be examined. Highly-efficient systems for sanitary hot water production are to be looked at, as are miniaturisation and new solutions for the installation of heating and cooling systems with heat pumps. Also the development of environmental-friendly working fluids for heat pumps and refrigeration plants is planned. Pilot and demonstration projects are also to be supported in all areas.

  14. An inverse method for calculation of thermal inertia and heat gain in air conditioning and refrigeration systems

    International Nuclear Information System (INIS)

    Fayazbakhsh, M.A.; Bagheri, F.; Bahrami, M.

    2015-01-01

    Highlights: • An inverse method is proposed to calculate thermal inertia in HVAC-R systems. • Real-time thermal loads are estimated using the proposed intelligent algorithm. • Calculation algorithm is validated with on-site measurements. • Freezer duty cycle data are extracted only based on temperature measurements. - Abstract: A new inverse method is proposed for estimation of thermal inertia and heat gain in air conditioning and refrigeration systems using on-site temperature measurements. The method is applied on a walk-in freezer room of a restaurant in Surrey, British Columbia, Canada during one week of its regular operation. The thermal inertia and instantaneous heat gain are calculated and the results are validated using actual information of the materials inside the freezer room. The proposed method can be implemented in intelligent control systems designed for new and existing HVAC-R systems to improve their overall energy efficiency and reduce their environmental impacts

  15. Economic analysis of wind-powered refrigeration cooling/water-heating systems in food processing. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Garling, W.S.; Harper, M.R.; Merchant-Geuder, L.; Welch, M.

    1980-03-01

    Potential applications of wind energy include not only large central turbines that can be utilized by utilities, but also dispersed systems for farms and other applications. The US Departments of Energy (DOE) and Agriculture (USDA) currently are establishing the feasibility of wind energy use in applications where the energy can be used as available, or stored in a simple form. These applications include production of hot water for rural sanitation, heating and cooling of rural structures and products, drying agricultural products, and irrigation. This study, funded by USDA, analyzed the economic feasibility of wind power in refrigeration cooling and water heating systems in food processing plants. Types of plants included were meat and poultry, dairy, fruit and vegetable, and aquaculture.

  16. Cooling high heat flux micro-electronic systems using refrigerants in high aspect ratio multi-microchannel evaporators

    International Nuclear Information System (INIS)

    Costa-Patry, E.

    2011-11-01

    Improving the energy efficiency of cooling systems can contribute to reduce the emission of greenhouse gases. Currently, most microelectronic applications are air-cooled. Switching to two-phase cooling systems would decrease power consumption and allow for the reuse of the extracted heat. For this type of application, multi-microchannel evaporators are thought to be well adapted. However, such devices have not been tested for a wide range of operating conditions, such that their thermal response to the high non-uniform power map typically generated by microelectronics has not been studied. This research project aims at clarifying these gray areas by investigating the behavior of the two-phase flow of different refrigerants in silicon and copper multi-microchannel evaporators under uniform, non-uniform and transient heat fluxes operating conditions. The test elements use as a heat source a pseudo-chip able to mimic the behavior of a CPU. It is formed by 35 independent sub-heaters, each having its own temperature sensor, such that 35 temperature and 35 heat flux measurements can be made simultaneously. Careful measurements of each pressure drop component (inlet, microchannels and outlet) found in the micro-evaporators showed the importance of the inlet and outlet restriction pressure losses. The overall pressure drop levels found in the copper test section were low enough to possibly be driven by a thermosyphon system. The heat transfer coefficients measured for uniform heat flux conditions were very high and typically followed a V-shape curve. The first branch was associated to the slug flow regime and the second to the annular flow regime. By tracking the minimum level of heat transfer, a transition criteria between the regimes was established, which included the effect of heat flux on the transition. Then for each branch, a different prediction method was used to form the first flow pattern-based prediction method for two-phase heat transfer in microchannels. A

  17. Experimental study on two-stage compression refrigeration/heat pump system with dual-cylinder rolling piston compressor

    International Nuclear Information System (INIS)

    Shuxue, Xu; Guoyuan, Ma

    2014-01-01

    A thermodynamically analytical model on the two-stage compression refrigeration/heat pump system with vapor injection was derived. The optimal volume ratio of the high-pressure cylinder to the low-pressure one has been discussed under both cooling and heating conditions. Based on the above research, the prototype was developed and its experimental setup established. A comprehensive experiments for the prototype have been conducted, and the results show that, compared with the single-stage compression heat pump system, the cooling capacity and cooling COP can increase 5%–15% and 10–12%, respectively. Also, the heating capacity with the evaporating temperature ranging from 0.3 to 3 °C is 92–95% of that under the rate condition with the evaporating temperature of 7 °C, and 58% when the evaporation temperature is between −28 °C and −24 °C. -- Highlights: • The volume ratio of the compressor is between 0.65 and 0.78 and the relative vapor injection mass ranges from 15% to 20%. • The cooling capacity and COP of the two-stage compression system can improve 5%–15% and 10%–12%. • The heating capacity can also be improved under low temperature condition

  18. Use of process steam in vapor absorption refrigeration system for cooling and heating applications: An exergy analysis

    Directory of Open Access Journals (Sweden)

    S. Anand

    2016-12-01

    Full Text Available The exponential increase in cost of conventional fuels shifts the interest toward the use of alternative as well waste energy sources for the operation of refrigeration and air-conditioning units. The present study therefore analyzes the performance of a process steam-operated vapor absorption system for cooling and heating applications using ammonia and water as working fluids based on first and second laws of thermodynamics. A mathematical model has been developed based on exergy analysis to investigate the performance of the system. The different performance parameters such as coefficient of performance (COP and exergetic efficiency of absorption system for cooling and heating applications are also calculated under different operating conditions. The results obtained show that cooling and heating COP along with second law efficiency (exergy efficiency increases with the heat source temperature at constant evaporator, condenser, and absorber temperature. Also, COP as well as exergy efficiency increases with an increase in the evaporator temperature at constant generator, condenser, and absorber temperature. The effect of ambient temperature on the exergetic efficiency for cooling and heating applications is also studied. The results obtained from the simulation studies can be used to optimize different components of the system so that the performance can be improved significantly.

  19. Physical, chemical, microbiological and sensorial behaviour evolution of non cooked pressed cheese paste while in refrigerated storage, made with red chilli powder, treated by heat or ionization

    International Nuclear Information System (INIS)

    Iben El Hadj Mohamed, A.

    1998-01-01

    The evolution of different physical, chemical, microbiological and sensorial characteristics of a Tunisian manufactured cheese made of non cooked pressed cheese paste with red chilli powder treated by heat, was measured while in refrigerated storage and compared to the one treated by ionization (author)

  20. Articulated, Performance-Based Instruction Objectives Guide for Air Conditioning, Refrigeration, and Heating (Environmental Control System Installer/Servicer). Edition I.

    Science.gov (United States)

    Henderson, William Edward, Jr., Ed.

    This articulation guide contains 17 units of instruction for the first 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 to introduce the student to fundamental theories…

  1. A thermodynamic analysis of a transcritical cycle with refrigerant mixture R32/R290 for a small heat pump water heater

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Jianlin; Xu, Zong; Tian, Gaolei [Department of Refrigeration and Cryogenic Engineering, School of Energy and Power Engineering, Xi' an Jiaotong University, West Xianning Road, No. 28, Xianning West Road, Xi' an Shaanxi 710049 (China)

    2010-12-15

    In this study, a thermodynamic analysis on the performance of a transcritical cycle using azeotropic refrigerant mixtures of R32/R290 with mass fraction of 70/30 has been performed. The main purpose of this study is to theoretically verify the possibility of applying the chosen refrigerant mixture in small heat pumps for high temperature water heating applications. Performance evaluation has been carried out for a simple azeotropic mixture R32/R290 transcritical cycle by varying evaporator temperature, outlet temperature of gas cooler and compressor discharge pressure. Furthermore, the effects of an internal heat exchanger on the transcritical R32/R290 cycle have been presented at different operating conditions. The results show that high heating coefficient of performance (COP{sub h}) and volumetric heating capacity can be achieved by using this transcritical cycle. It is desirable to apply the chosen refrigerant mixture R32/R290 in small heat pump water heater for high temperature water heating applications, which may produce hot water with temperature up to 90 C. (author)

  2. Combined heat and power generation with exhaust-heated two-stage absorption refrigerator. Performance of a pilot installation with a refrigeration capacity of 350 kW; Kraft-Waerme-Kaelte-Kopplung mit Abgas-Beheizter zweistufiger Absorptionskaeltemaschine. Betriebserfahrungen einer Pilotinstallation mit 350 kW Kaelteleistung

    Energy Technology Data Exchange (ETDEWEB)

    Plura, S.; Baumeister, D.; Koeberle, T.; Radspieler, M.; Schweigler, C. [Bayerisches Zentrum fuer Angewandte Energieforschung e.V. (ZAE Bayern), Garching (Germany)

    2007-07-01

    A new system concept for higher efficiency of cogeneration systems is developed in which a cogeneration unit is combined with a two-stage absorption refrigerator, and the waste heat of the cogeneration unit is directly passed on into the regenerator of the absorption refrigerator. The higher temperature level of the waste heat makes it possible to use a two-stage absorption cycle for higher energy efficiency. For simultaneous utilisation of low-temperature heat, the two-stage cycle is combined with a one-stage cycle for additional heat supply at a lower temperature level so that the exhaust of a typical cogeneration unit will be cooled to about 120 degC. At the same time, further waste heat of the cogeneration unit will be transferred to the heat pump via a hot water circuit. This concept with a combined single-stage and two-stage absorption circuit is referred to as a double-effect/single-effect circuit. The new system is used for energy supply in a spa, where the two-stage absorption refrigerator cools the water used for swimming pool cleaning with a refrigerating capacity of 350 kW and provides low-temperature heat for swimming pool heating with a capacity of 700 kW. (orig.)

  3. Combined refrigeration / heat pump installation at the St. Jakob Arena in Basle; Kombinierte Kaelte- / Waermepumpen- Verdichter-Anlage in der Eissporthalle St. Jakob ARENA, 4142 Muenchenstein, Basel

    Energy Technology Data Exchange (ETDEWEB)

    Frey, P. [P. Frey and Partner, Beratende Ingenieure und Planer, Wilen bei Wil (Switzerland); Bertozzi, L. [Ingenieurbuero Bertozzi, Ingenieurbuero fuer Haustechnik, Chur (Switzerland)

    2003-07-01

    This intermediate report for the Swiss Federal Office of Energy describes the combined refrigeration and heat-pump unit in use at the new 'St. Jakob Arena' ice-sport-centre near Basle, Switzerland, which includes an indoor ice-rink. The centre has been equipped with an ammonia-based refrigeration system with two reciprocating compressors, which can be run in parallel or as part of a 2-stage-process. The two modes of operation are described. In the 'parallel' operating mode, both compressors are used for cold production only. In the '2-stage' operating mode, one compressor acts as the lower stage for cold production an the second as the upper stage for heat production using the rejected heat from condenser of the first stage as a heat source. Data is presented on the system's performance during the first operational season of the installation.

  4. R13B1 and R114 exergy-enthalpy charts and their usefulness in a refrigerating-heating process analysis

    International Nuclear Information System (INIS)

    de Rossi, F.; Mastrullo, R.; Sasso, M.; Sibilio, S.

    1989-01-01

    R13B1 and R114 exergy-enthalpy diagrams in SI units based on data and equations published by the International Institute of Refrigeration are presented. The charts cover the ranges of 0.5 kPa to 15000 kPa and 120 degrees C to 180 degrees C for R13B1 and 0.8 kPa to 5000 kPa and -70 degrees C to 250 degrees C for R114. In this paper an analysis of a cascade refrigerating-heating compound system is included to illustrate the use of the charts

  5. Post-Dryout Heat Transfer to a Refrigerant Flowing in Horizontal Evaporator Tubes

    Science.gov (United States)

    Mori, Hideo; Yoshida, Suguru; Kakimoto, Yasushi; Ohishi, Katsumi; Fukuda, Kenichi

    Studies of the post-dryout heat transfer were made based on the experimental data for HFC-134a flowing in horizontal smooth and spiral1y grooved (micro-fin) tubes and the characteristics of the post-dryout heat transfer were c1arified. The heat transfer coefficient at medium and high mass flow rates in the smooth tube was lower than the single-phase heat transfer coefficient of the superheated vapor flow, of which mass flow rate was given on the assumption that the flow was in a thermodynamic equilibrium. A prediction method of post-dryout heat transfer coefficient was developed to reproduce the measurement satisfactorily for the smooth tube. The post dryout heat transfer in the micro-fin tube can be regarded approximately as a superheated vapor single-phase heat transfer.

  6. Stirling Refrigerator

    Science.gov (United States)

    Kagawa, Noboru

    A Stirling cooler (refrigerator) was proposed in 1862 and the first Stirling cooler was put on market in 1955. Since then, many Stirling coolers have been developed and marketed as cryocoolers. Recently, Stirling cycle machines for heating and cooling at near-ambient temperatures between 173 and 400K, are recognized as promising candidates for alternative system which are more compatible with people and the Earth. The ideal cycles of Stirling cycle machine offer the highest thermal efficiencies and the working fluids do not cause serious environmental problems of ozone depletion and global warming. In this review, the basic thermodynamics of Stirling cycle are briefly described to quantify the attractive cycle performance. The fundamentals to realize actual Stirling coolers and heat pumps are introduced in detail. The current status of the Stirling cycle machine technologies is reviewed. Some machines have almost achieved the target performance. Also, duplex-Stirling-cycle and Vuilleumier-cycle machines and their performance are introduced.

  7. Research and development of utilization technology of solar thermal system for industrial and other use. Development of system of advanced heat process type (chemical refrigeration and cold storage system using solar heat); Sangyoyo nado solar system jitsuyoka gijutsu kaihatsu. Advanced heat process gata system no kaihatsu (taiyonetsu reito reizo no kaihatsu)

    Energy Technology Data Exchange (ETDEWEB)

    Takita, M [New Energy and Industrial Technology Development Organization, Tokyo (Japan)

    1994-12-01

    Described herein are the results of the FY1994 research program for chemical refrigeration and cold storage system using solar heat. The study on refrigeration materials are aimed at development of new hydrogen-occluding alloys which show good hydrogenation equilibrium characteristics and reactivity at temperature required for stand-alone refrigeration systems aided by solar heat, and still new hydrogen-occluding alloys operable at refrigeration temperature for lower-temperature systems. For the refrigeration materials capable of producing low-temperature heat of -10{degree}C at a regeneration temperature of 140{degree}C produced by solar heat, a La-Ni-Mn-Al alloy is selected for high-temperature use and a La-Y-Ni-Mn alloy for low-temperature use. The study on technology for refrigeration modules develops high-efficiency heat exchangers for refrigeration and regeneration, compatible with the hydrogen-occluding alloys. It also develops air-and water-cooling techniques for hydrogen-occluding alloys, where air is used as the heat source. The test apparatus is designed, installed and operated, to attain a low temperature of -10{degree}C or lower with a heat source of 140{degree}C and air heat source of 28{degree}C. 7 figs.

  8. Experimental results for hydrocarbon refrigerant vaporization in brazed plate heat exchangers at high pressure

    OpenAIRE

    Desideri, Adriano; Rhyl Kaern, Martin; Ommen Schmidt, Torben; Wronski, Jorrit; Quoilin, Sylvain; Lemort, Vincent; Haglind, Fredrik

    2016-01-01

    In recent years the interest in small capacity organic Rankine cycle (ORC) power systems for harvesting low quality waste thermal energy from industrial processes has been steadily growing. Micro ORC systems are normally equipped with brazed plate heat exchangers which allows for efficient heat transfer with a compact design. An accurate prediction of the heat transfer process characterizing these devices is required from the design phase to the development of model- based control strategies....

  9. 2014 German refrigeration and air conditioning meeting. Proceedings

    International Nuclear Information System (INIS)

    2014-01-01

    The proceedings of the 2014 German refrigeration and air conditioning meeting contain contributions on the following topics: cryotechnology, fundamentals and materials for the refrigeration and heat pump technology, devices and components for the refrigeration and heat pump technology, applications of refrigeration technologies, air conditioning technology and heat pump applications, cryotechnology in biology and medicine, heat transfer and ventilation, guidelines and legal topics, refrigerant fluid - oil mixtures, control and surveillance, simulation and control, ambient air.

  10. The performance of a residential heat pump operating with a nonazeotropic binary refrigerant mixture

    Science.gov (United States)

    Didion, D.; Mulroy, W.

    Results of laboratory measurement of the performance change of a substantially unmodified residential heat pump designed for 222 when charged with a non azeotropic, binary mixture of R1381 and R152a is presented. Results are presented for various sizes of fixed expansion devices. The effect of gliding temperature in the saturation zone was found to be small. The effect of compositions shift by flash distillation in the accumulator was found to measurably improve low temperature heating performance. It was further observed that some system modification (such as the addition of a receiver) could have further enhanced this low temperature heating performance improvement.

  11. Low Global Warming Potential Refrigerants for Commercial Refrigeration Systems

    Energy Technology Data Exchange (ETDEWEB)

    Fricke, Brian A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Sharma, Vishaldeep [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Abdelaziz, Omar [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-06-01

    Supermarket refrigeration systems account for approximately 50% of supermarket energy use, placing this class of equipment among the highest energy consumers in the commercial building domain. In addition, the commonly used refrigeration system in supermarket applications is the multiplex direct expansion (DX) system, which is prone to refrigerant leaks due to its long lengths of refrigerant piping. This leakage reduces the efficiency of the system and increases the impact of the system on the environment. The high Global Warming Potential (GWP) of the hydrofluorocarbon (HFC) refrigerants commonly used in these systems, coupled with the large refrigerant charge and the high refrigerant leakage rates leads to significant direct emissions of greenhouse gases into the atmosphere. Environmental concerns are driving regulations for the heating, ventilating, air-conditioning and refrigeration (HVAC&R) industry towards lower GWP alternatives to HFC refrigerants. Existing lower GWP refrigerant alternatives include hydrocarbons, such as propane (R-290) and isobutane (R-600a), as well as carbon dioxide (R-744), ammonia (R-717), and R-32. In addition, new lower GWP refrigerant alternatives are currently being developed by refrigerant manufacturers, including hydrofluoro-olefin (HFO) and unsaturated hydrochlorofluorocarbon (HCFO) refrigerants. The selection of an appropriate refrigerant for a given refrigeration application should be based on several factors, including the GWP of the refrigerant, the energy consumption of the refrigeration system over its operating lifetime, and leakage of refrigerant over the system lifetime. For example, focusing on energy efficiency alone may overlook the significant environmental impact of refrigerant leakage; while focusing on GWP alone might result in lower efficiency systems that result in higher indirect impact over the equipment lifetime. Thus, the objective of this Collaborative Research and Development Agreement (CRADA) between

  12. Combined heat pump for sanitary hot water and space heating with CO{sub 2} as refrigerant; Kombineret brugsvands- og rumvarmepumpe med CO{sub 2} som koelemiddel

    Energy Technology Data Exchange (ETDEWEB)

    Schoen Poulsen, C. [Teknologisk Institut (Denmark)

    2006-05-19

    This project report describes the implementation of the Danish project called 'Combined heat pump for sanitary hot water and space heating with CO{sub 2} as refrigerant'. In the course of the project, a combined heat pump has been developed for heating sanitary hot water and producing domestic space heating. The project shows that CO2 has excellent properties in systems where a high temperature is desired on the gas cooler side and that it is possible to combine the production of sanitary hot water with the production of domestic space heating. During the project, a number of system solutions have been analysed and at the end of the project a prototype was built. It was tested in the laboratory according to a current Dutch standard for heat pumps for sanitary hot water. The prototype was constructed without the space heat part which solely has been analysed according to calculations. The reason is that there currently are no applicable European standards for the testing of combined systems and as the total efficiency of the system mainly depends on the temperature out of the gas cooler it was decided not to spend resources on the construction of the combined system in the prototype version of the unit. Instead, a number of proposals have been submitted to how the system with a space heat section could be constructed. The main components used in the prototype (compressor, exchangers, valve, control and tank) are all partly commercially available and therefore focus has been on the system construction. During the project, a number of CFD calculations have been carried out on the gas cooler in the hot water tank and the results show how important it is that the gas cooler is designed and placed correctly. The laboratory tests carried out on the unit show that the COP of the heat pump plant in connection with sanitary hot water tapping (according to Dutch standard) is 1.4 1.5 which is not immediately satisfactory. But when it is considered that the unit is a

  13. Use of Disinfectants and Sanitizers in Heating, Ventilation, Air Conditioning, and Refrigeration Systems

    Science.gov (United States)

    This letter is to brings attention several concerns that the Agency has regarding the use of sanitizer and/or disinfectant products, and other types of antimicrobial products, to treat the surfaces of heating, ventilation

  14. Refrigerated display cabinets; Butikskyla

    Energy Technology Data Exchange (ETDEWEB)

    Fahlen, Per

    2000-07-01

    This report summarizes experience from SP research and assignments regarding refrigerated transport and storage of food, mainly in the retail sector. It presents the fundamentals of heat and mass transfer in display cabinets with special focus on indirect systems and secondary refrigerants. Moreover, the report includes a brief account of basic food hygiene and the related regulations. The material has been compiled for educational purposes in the Masters program at Chalmers Technical University.

  15. Indirect refrigeration systems with natural refrigerants

    DEFF Research Database (Denmark)

    Knudsen, Hans Jørgen Høgaard; Christensen, Kim Gardø; Jensen, Per Henrik

    1998-01-01

    Heat transfer for boiling and condensing carbon dioxide has been investigated.Heat transfer for carbon dioxide evaporating inside pipe has been measured and compared with Shah's correlation. The measured heat transfer coefficient is much higher than the value determined with the correlation.A shell......-and-tube heat exchanger with carbon dioxide on the shell side and flow ice inside the tubes has been used to investigate the heat transfer for condensing carbon dioxide.At leats is mentioned results obtained with a frozen food display case using carbone dioxide as refrigerant....

  16. Satellite air temperature estimation for monitoring the canopy layer heat island of Milan

    DEFF Research Database (Denmark)

    Pichierri, Manuele; Bonafoni, Stefania; Biondi, Riccardo

    2012-01-01

    across the city center from June to September confirming that, in Milan, urban heating is not an occasional phenomenon. Furthermore, this study shows the utility of space missions to monitor the metropolis heat islands if they are able to provide nighttime observations when CLHI peaks are generally......In this work, satellite maps of the urban heat island of Milan are produced using satellite-based infrared sensor data. For this aim, we developed suitable algorithms employing satellite brightness temperatures for the direct air temperature estimation 2 m above the surface (canopy layer), showing...... 2007 and 2010 were processed. Analysis of the canopy layer heat island (CLHI) maps during summer months reveals an average heat island effect of 3–4K during nighttime (with some peaks around 5K) and a weak CLHI intensity during daytime. In addition, the satellite maps reveal a well defined island shape...

  17. Helium dilution refrigerator

    International Nuclear Information System (INIS)

    1973-01-01

    A new system of continuous heat exchange for a helium dilution refrigerator is proposed. The 3 He effluent tube is concurrent with the affluent mixed helium tube in a vertical downward direction. Heat exchange efficiency is enhanced by placing in series a number of elements with an enlarged surface area

  18. Performance study on a low-temperature absorption–compression cascade refrigeration system driven by low-grade heat

    International Nuclear Information System (INIS)

    Xu, Yingjie; Chen, Guangming; Wang, Qin; Han, Xiaohong; Jiang, Ning; Deng, Shiming

    2016-01-01

    Highlights: • An absorption–compression system for low-temperature is developed and analyzed. • Cooling capacity, compression power, and discharge temperature are all improved. • At −170 °C, giving 200 W low-grade cooling capacity, COP increases by 28.6%. • Simulation results are verified experimentally, showing good agreement. - Abstract: This paper presents a performance study on a low-temperature absorption–compression cascade refrigeration system (LACRS), which consists of an absorption subsystem (AS) and a vapor compression auto-cascade subsystem (CS). In the system, low-grade heat of AS is used to subcool the CS, which can obtain cold energy at −170 °C. A simulation study is carried out to investigate the effects of evaporating temperature and low-grade cooling capacity on system performance. The study results show that as low-grade cooling capacity from the AS is provided to the CS, high-grade cooling capacity increases, compressor power consumption decreases, and the COP of the CS therefore increases. Comparing with compression auto-cascade cycle, the largest COP improvement of LACRS is about 38%. The model is verified by experimental data. An additional high-grade cooling capacity is obtained experimentally at −170 °C. The study results presented in this paper not only demonstrate the excellent performance of the LACRS, but also provide important guidance to further system design, and practical application.

  19. Experimental results for hydrocarbon refrigerant vaporization inside brazed plate heat exchangers at high pressure

    DEFF Research Database (Denmark)

    Desideri, Adriano; Ommen, Torben Schmidt; Wronski, Jorrit

    2016-01-01

    fluids at typical working conditions of ORC systems for low temperature waste heat recovery (WHR) applications. Based on these premises, a novel testrig has been recently designed and built at the Technical University of Denmark to simulate the evaporating condition occurring in a small capacity ORC...... power unit. In this contribution the preliminary experimental results obtained from the first experimental campaign carried out on the rig are reported. HFC-134a was selected as working fluid. The experiments were carried out at saturation temperature of 60, 70 and 80 °C and inlet and outlet qualities...

  20. Efficiency improvement of commercial refrigeration systems

    Energy Technology Data Exchange (ETDEWEB)

    Denecke, Julius [NTNU, Trondheim (Norway); Hafner, Armin [SINTEF Energy Research, Trondheim (Norway)

    2011-07-01

    This work presents a historical review of carbon dioxide refrigeration systems. Further a literature survey is carried out to get a status of existing refrigeration technology related to supermarkets. In the next step various energy saving options are stated. A heat recovery model, basing on a R744 booster refrigeration system is established and described. Simplified demand curves for refrigeration, air conditioning and heating will base this model to calculate different heat recovery layouts. Supermarket future trends will be considered and integrated in the calculation. Finally the calculated energy consumptions will be compared with real energy consumptions of selected supermarket refrigeration systems.

  1. Experience with small turbomachinery in a 400 watt refrigerator

    International Nuclear Information System (INIS)

    Fuerst, J.D.

    1996-09-01

    A refrigerator similar to one of the Fermilab Tevatron satellites was reconfigured to use turbomachinery instead of the reciprocating equipment typical of the installations. A Sulzer dry turboexpander, Creare wet turboexpander, and IHI centrifugal cold compressor have been installed and operated for about 8000 hours. Experience was gained both with the rotating machinery and with the refrigerator itself as it interfaced with the load. Equipment was set up to regulate in the same manner as the reciprocating devices had. Heat load and operating mode were adjusted and evaluations made regarding the behavior of the devices. Individual equipment performance is described as well as system behavior and overall integration of the machinery. In particular, attention is paid to the Creare wet turboexpander. This device is operated for the first time as part of a full scale refrigeration system, testing not only its performance at the design point but also its off design characteristics and behavior in transient situations

  2. Experience with small turbomachinery in a 400 watt refrigerator

    International Nuclear Information System (INIS)

    Fuerst, J.D.

    1996-01-01

    A refrigerator similar to one of the Fermilab Tevatron satellites was re-configured to use turbomachinery instead of the reciprocating equipment typical of the installations. A Sulzer dry turboexpander, Creare wet turboexpander, and IHI centrifugal cold compressor have been installed and operated for about 8000 hours. Experience was gained both with the rotating machinery and with the refrigerator itself as it interfaced with the load. Equipment was set up to regulate in the same manner as the reciprocating devices had. Heat loads and operating mode were adjusted and evaluations made regarding the behavior of the devices. Individual equipment performance is described, as well as system behavior and overall integration of the machinery. In particular, attention is paid to the Creare wet turboexpander. This device is operated for the first time as part of a full scale refrigeration system, testing not only its performance at the design point but also its off design characteristics and behavior in transient situations

  3. Energy saving in heat exchangers of industrial refrigeration systems; Ahorro de energia en intercambiadores de calor en los sistemas de refrigeracion industrial

    Energy Technology Data Exchange (ETDEWEB)

    Padilla, A; Romero Paredes, Hernando; Ambriz, Juan Jose [Universidad Autonoma Metropolitana-Iztapalapa, Mexico, D. F. (Mexico)

    1994-12-31

    This paper presents the energy losses of the heat exchangers utilized in industrial refrigeration systems . The effects of the different scaling products on the heat transfer rates are presented and the energy not transferred because of them is evaluated. A simplified method for the evaluation is developed and applied to the evaporators and condensers more frequently employed in the industrial refrigeration systems. The internal and external heat transfer coefficients are evaluated in different types of heat exchangers. The energy losses as a function of the scale thickness on the heat exchanger is shown. [Espanol] El trabajo presenta las perdidas energeticas que se tienen en los intercambiadores de calor usados en los sistemas de refrigeracion industrial. Se presentan los efectos que tienen los diferentes incrustantes en las tasas de transferencia de calor y se evalua la energia que no se transfiere causada por aquellos. Se desarrolla un metodo simplificado de evaluacion y se aplica a los evaporadores y condensadores mas comunes empleados en los sistemas de refrigeracion industrial. Se evaluan los coeficientes internos y externos en diferentes tipos de intercambiadores. Se muestran las perdidas energeticas en funcion del espesor del incrustante en la pared del intercambiador.

  4. Development of two-stage compression heat pump for hot water supply in commercial use. Research of compatibility with alternative refrigerant, HFC-134a; Gyomuyo nidan asshukushiki kyuto heat pump no kaihatsu. Daitai reibai HFC-134a no tekiyosei kensho

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, K.; Hasegawa, H.; Saikawa, M.; Iwatsubo, T.; Mimaki, T. [Central Research Institute of Electric Power Industry, Tokyo (Japan)

    1996-03-01

    Performance of two-stage compression and cascade heating heat pump cycle was evaluated in the case using alternative refrigerant, HFC-134a, instead of CFC-12 through calculations and experiments. Heat source and heat load temperature conditions of CFC-12, HFC-134a, and HCFC-22 were calculated. As a result, this cycle provided equivalent coefficient of performance to use of CFC-12 and HCFC-22. Especially for HFC-134a, discharge gas temperature from compressor was much lower than that of the others, which prevented the heat decomposition of refrigerant. It was found that HFC-134a was suitable refrigerant for high temperature output equipment like this cycle. To grasp the possibility of hot water supply at 65 {degree}C and behavior of lubricating oil which can not be obtained only from calculations, applicability of HFC-134a was investigated. Experiments were conducted using a small test apparatus with electric input of 2 kW. As a result, satisfactory performance was obtained for each evaluation item. Applicability of HFC-134a to the two-stage compression cycle was confirmed. 9 refs., 21 figs., 16 tabs.

  5. Geothermal Heat Flux Underneath Ice Sheets Estimated From Magnetic Satellite Data

    DEFF Research Database (Denmark)

    Fox Maule, Cathrine; Purucker, M.E.; Olsen, Nils

    The geothermal heat flux is an important factor in the dynamics of ice sheets, and it is one of the important parameters in the thermal budgets of subglacial lakes. We have used satellite magnetic data to estimate the geothermal heat flux underneath the ice sheets in Antarctica and Greenland...

  6. Mixed layer heat budget of Kuroshio-Tango Triangle using satellite and ship observations

    Digital Repository Service at National Institute of Oceanography (India)

    Pankajakshan, T.; Akiyama, M.; Sugimori, Y.; Wuwa, J.; Okada, Y.; Siripong, A.

    heat flux across the air-sea boundary both satellite (NIMBUS-7 SMMR) and ship observations are used. The advective fluxes across the lateral boundaries of the system are derived from sequential images of AVHRR. The net heat divergence of the triangular...

  7. Accelerated life tests of specimen heat pipe from Communication Technology Satellite (CTS) project

    Science.gov (United States)

    Tower, L. K.; Kaufman, W. B.

    1977-01-01

    A gas-loaded variable conductance heat pipe of stainless steel with methanol working fluid identical to one now on the CTS satellite was life tested in the laboratory at accelerated conditions for 14 200 hours, equivalent to about 70 000 hours at flight conditions. The noncondensible gas inventory increased about 20 percent over the original charge. The observed gas increase is estimated to increase operating temperature by about 2.2 C, insufficient to harm the electronic gear cooled by the heat pipes in the satellite. Tests of maximum heat input against evaporator elevation agree well with the manufacturer's predictions.

  8. Experimental validation of a new sorption refrigerator heated by natural gas; Validacao experimental de um refigerador de sorcao aquecido por gas natural

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Maria E. Vieira da; Medeiros, Marcelo R.Q. [Universidade Federal do Ceara (UFC), Fortaleza, CE (Brazil); Schwarzer, Klemens [Universidade de Ciencias Aplicadas de Aachen (Germany); Campos, Michel F. [PETROBRAS, Rio de Janeiro, RJ (Brazil)

    2004-07-01

    This article presents the experimental results that validate the operation of a new refrigerator in sorption cycle that uses natural gas as its heat source. The project was financed by the RedeGasEnergia of the Petroleo Brasileiro Company - PETROBRAS and by Brazilian agency Agencia Brasileira Financiadora de Estudos e Projetos - FINEP. The refrigeration cycle has two phases: heating/desorption and cooling/adsorption. The materials used were the zeolite 13X and water. The system components, designed for this project, were: two adsorbers, two burners, one condenser and one evaporator. In the heating phase, the burners were turned on to heat up the adsorbers. The adsorbate was released in the vapor phase e flew to the condenser. After its condensation, the liquid moved by the action of gravity to the evaporator. When the burners were turned off, the adsorbers started to cool down due to natural convection and radiation to the ambient. With the decrease of temperature in the adsorbers, the adsorption process began and temperatures below 0 deg C (ice making) were measured in the evaporator. The equipment showed good thermal performance and temperatures near -4 deg C were measured in the evaporator. To produce 5 kg of ice, 0,123 kg of natural gas was used. (author)

  9. Ecological optimization for generalized irreversible Carnot refrigerators

    International Nuclear Information System (INIS)

    Chen Lingen; Zhu Xiaoqin; Sun Fengrui; Wu Chih

    2005-01-01

    The optimal ecological performance of a Newton's law generalized irreversible Carnot refrigerator with the losses of heat resistance, heat leakage and internal irreversibility is derived by taking an ecological optimization criterion as the objective, which consists of maximizing a function representing the best compromise between the exergy output rate and exergy loss rate (entropy production rate) of the refrigerator. Numerical examples are given to show the effects of heat leakage and internal irreversibility on the optimal performance of generalized irreversible refrigerators

  10. Flammable refrigerants

    NARCIS (Netherlands)

    Gerwen, R.J.M. van; Verwoerd, M.; Oostendorp, P.A.

    1999-01-01

    Hydrocarbons are promising alternatives for CFC, HCFC and HFC refrigerants. Due to their flammable nature, safety aspects have to be considered carefully. The world-wide situation concerning acceptability and practical application of flammable refrigerants is becoming more and more complex and

  11. Overall performance of the duplex Stirling refrigerator

    International Nuclear Information System (INIS)

    Erbay, L. Berrin; Ozturk, M. Mete; Doğan, Bahadır

    2017-01-01

    Highlights: • Overall performance coefficient of duplex Stirling refrigerator was investigated. • A definite region for the coefficient of performance of the refrigerator in duplex Stirling is identified. • A definite region for the thermal efficiency of the heat engine in duplex Stirling is identified. • Benchmark values and design bounds of the duplex Stirling refrigerator were obtained. - Abstract: The duplex Stirling refrigerator is an integrated refrigerator consists of Stirling cycle engine and Stirling cycle refrigerator used for cooling. The equality of the work generation of the heat engine to the work consumption of the refrigerator is the primary constraint of the duplex Stirling. The duplex Stirling refrigerator is investigated thermodynamically by considering the effects of constructional and operational parameters which are namely the temperature ratios for heat engine and refrigerator, and the compression ratios for both sides. The primary concern is given to the parametric effects on the overall coefficient of performance of the duplex Stirling refrigerator. The given diagrams provide a design bounds and benchmark results that allows seeing the big picture about the cooling load and heat input relation. Moreover they ease to determine the corresponding work rate to the target cooling load. As regard to the obtained results, a definite region for coefficient of performance of the refrigerator and a definite region for the thermal efficiency of the heat engine of the duplex Stirling are identified.

  12. Satellites

    International Nuclear Information System (INIS)

    Burns, J.A.; Matthews, M.S.

    1986-01-01

    The present work is based on a conference: Natural Satellites, Colloquium 77 of the IAU, held at Cornell University from July 5 to 9, 1983. Attention is given to the background and origins of satellites, protosatellite swarms, the tectonics of icy satellites, the physical characteristics of satellite surfaces, and the interactions of planetary magnetospheres with icy satellite surfaces. Other topics include the surface composition of natural satellites, the cratering of planetary satellites, the moon, Io, and Europa. Consideration is also given to Ganymede and Callisto, the satellites of Saturn, small satellites, satellites of Uranus and Neptune, and the Pluto-Charon system

  13. Dual source heat pump

    Science.gov (United States)

    Ecker, Amir L.; Pietsch, Joseph A.

    1982-01-01

    What is disclosed is a heat pump apparatus for conditioning a fluid characterized by a fluid handler and path for circulating the fluid in heat exchange relationship with a refrigerant fluid; at least two refrigerant heat exchangers, one for effecting heat exchange with the fluid and a second for effecting heat exchange between refrigerant and a heat exchange fluid and the ambient air; a compressor for efficiently compressing the refrigerant; at least one throttling valve for throttling liquid refrigerant; a refrigerant circuit; refrigerant; a source of heat exchange fluid; heat exchange fluid circulating device and heat exchange fluid circuit for circulating the heat exchange fluid in heat exchange relationship with the refrigerant; and valves or switches for selecting the heat exchangers and direction of flow of the refrigerant therethrough for selecting a particular mode of operation. The heat exchange fluid provides energy for defrosting the second heat exchanger when operating in the air source mode and also provides a alternate source of heat.

  14. Magnetic refrigeration apparatus and method

    Science.gov (United States)

    Barclay, John A.; Overton, Jr., William C.; Stewart, Walter F.

    1984-01-01

    The disclosure relates to refrigeration through magnetizing and demagnitizing a body by rotating it within a magnetic field. Internal and external heat exchange fluids and in one embodiment, a regenerator, are used.

  15. Review of investigations in eco-friendly thermoacoustic refrigeration system

    Directory of Open Access Journals (Sweden)

    Raut Ashish S.

    2017-01-01

    Full Text Available To reduce greenhouse gas emissions, internationally research and development is intended to improve the performance of conventional refrigeration system also growth of new-fangled refrigeration technology of potentially much lesser ecological impact. This paper gives brief review of research and development in thermoacoustic refrigeration also the existing situation of thermoacoustic refrigeration system. Thermoacoustic refrigerator is a novel sort of energy conversion equipment which converts acoustic power into heat energy by thermoacoustic effect. Thermoacoustic refrigeration is an emergent refrigeration technology in which there are no moving elements or any environmentally injurious refrigerants during its working. The concept of thermoacoustic refrigeration system is explained, the growth of thermoacoustic refrigeration, various investigations into thermoacoustic refrigeration system, various optimization techniques to improve coefficient of performance, different stacks and resonator tube designs to improve heat transfer rate, various gases, and other parameters like sound generation have been reviewed.

  16. Thermodynamic and heat transfer analyses for R1234yf and R1234ze(E) as drop-in replacements for R134a in a small power refrigerating system

    International Nuclear Information System (INIS)

    Janković, Zvonimir; Sieres Atienza, Jaime; Martínez Suárez, José Antonio

    2015-01-01

    In this paper we present two different analyses of R1234yf and R1234ze(E) as drop-in replacements for R134a in a small power refrigeration system. The first analysis is based on equal evaporation and condensation temperatures before and after the refrigerant replacement. The second analysis is carried out for equal cooling medium conditions in the condenser, so that the transport properties and the heat transfer features in the condenser are considered for the three refrigerants. In order to perform the analyses, a simulation model was developed, that takes into account specific data, characteristics and dimensions of the main components of a small power refrigeration system. The model was validated with experimental data for R134a and later used to predict the behavior with R1234yf and R1234ze(E). Results show that different conclusions may be drawn if the drop-in analysis is carried out for equal condensation temperatures or for equal temperatures of the cooling medium in the condenser, as well as that these results are affected by the condenser design. In general, R1234yf seems as an adequate drop-in refrigerant for R134a, but R1234ze(E) may perform better when an overridden compressor can be used to match the refrigerating system cooling power. - Highlights: • Low GWP refrigerants R1234yf and R1234ze(E) are potential replacements for R134a. • Refrigerating system mathematical model to predict drop-in performance. • Drop-in analysis for the same evaporation and condensation temperatures. • Drop-in analysis for the same cooling medium temperatures. • Refrigerant heat transfer features have a great impact on the drop-in performance

  17. The free-piston Vuilleumier machine: a new refrigerating sink from heat loss recovery?; La machine de Vuilleumier a pistons libres: une nouvelle source de froid par recuperation?

    Energy Technology Data Exchange (ETDEWEB)

    Rochelle, P. [Laboratoire de Mecanique Physique, UP6, 78 - Saint Cyr l' Ecole (France); Rochelle, P.; Grosu, L. [Laboratoire d' Energetique et d' Economie de l' Energie, UP10, 92 - Ville d' Avray (France)

    2002-07-01

    The Vuilleumier machine combines two Stirling cycles: a prime mover and a refrigerating cycle. lt could produce cold and heat at low temperature levels from heat loss recovered at the exhaust of heat generating processes (industrial transforming processes, thermal engines,...). Here, these regenerating dual cycle machines and their potential applications, particularly those concerning transportation vehicles, are examined. Towards this purpose, the Vuilleumier machine principles are briefly described along with a more in-depth look at the free-piston configuration type. In principle, these machines are simple to build, but specific starting and continuous running conditions must be met, and here they are established. Then, we discuss the applicability of these systems to vehicles, and the usable geometrical configurations are shortly examined with, as an application, the pre-design calculus of a 'pancake' machine. (authors)

  18. Refrigeration a history

    CERN Document Server

    Gantz, Carroll

    2015-01-01

    For thousands of years, humans coped with heat by harvesting and storing natural ice and devising natural cooling systems that utilized ventilation and evaporation. By the mid 1800s, people began developing huge refrigeration machines to manufacture ice. By the early 1900s, engineers developed electric domestic refrigerators, which by 1927 were affordable convenient household appliances. By then, an increasingly sophisticated public demanded more modern-looking appliances than engineers could produce, and a new breed of designers entered the manufacturing world to provide them. During the Depr

  19. Experimental study of no-frost refrigerator. Part 1: heat transfer through the walls; Estudo experimental de um refrigerador no-frost. Parte 1: transferencia de calor atraves das paredes

    Energy Technology Data Exchange (ETDEWEB)

    Goncalves, Joaquim Manoel [Escola Tecnica Federal de Santa Catarina, Sao Jose, SC (Brazil)]. E-mail: joaquim@nrva.ufsc.br; Melo, Claudio; Vieira, Luis Antonio Torquato [Santa Catarina Univ., Florianopolis, SC (Brazil). Dept. de Engenharia Mecanica

    2000-07-01

    This paper approaches the heat transfer in permanent regimen trough the walls of a no-frost refrigerator with two compartments with forced internal ventilation. The presented methodology allows the determination of thermal resistances of the walls externally. Also, the heating effect due to the compressor, the condenser and the air distribution between the compartments are investigated.

  20. Solar Powered Refrigeration System

    Science.gov (United States)

    Ewert, Michael K. (Inventor); Bergeron, David J., III (Inventor)

    2002-01-01

    A solar powered vapor compression refrigeration system is made practicable with thermal storage and novel control techniques. In one embodiment, the refrigeration system includes a photovoltaic panel, a variable speed compressor, an insulated enclosure, and a thermal reservoir. The photovoltaic (PV) panel converts sunlight into DC (direct current) electrical power. The DC electrical power drives a compressor that circulates refrigerant through a vapor compression refrigeration loop to extract heat from the insulated enclosure. The thermal reservoir is situated inside the insulated enclosure and includes a phase change material. As heat is extracted from the insulated enclosure, the phase change material is frozen, and thereafter is able to act as a heat sink to maintain the temperature of the insulated enclosure in the absence of sunlight. The conversion of solar power into stored thermal energy is optimized by a compressor control method that effectively maximizes the compressor's usage of available energy. A capacitor is provided to smooth the power voltage and to provide additional current during compressor start-up. A controller monitors the rate of change of the smoothed power voltage to determine if the compressor is operating below or above the available power maximum, and adjusts the compressor speed accordingly. In this manner, the compressor operation is adjusted to convert substantially all available solar power into stored thermal energy.

  1. Superfluid thermodynamic cycle refrigerator

    Science.gov (United States)

    Swift, Gregory W.; Kotsubo, Vincent Y.

    1992-01-01

    A cryogenic refrigerator cools a heat source by cyclically concentrating and diluting the amount of .sup.3 He in a single phase .sup.3 He-.sup.4 He solution. The .sup.3 He in superfluid .sup.4 He acts in a manner of an ideal gas in a vacuum. Thus, refrigeration is obtained using any conventional thermal cycle, but preferably a Stirling or Carnot cycle. A single phase solution of liquid .sup.3 He at an initial concentration in superfluid .sup.4 He is contained in a first variable volume connected to a second variable volume through a superleak device that enables free passage of .sup.4 He while restricting passage of .sup.3 He. The .sup.3 He is compressed (concentrated) and expanded (diluted) in a phased manner to carry out the selected thermal cycle to remove heat from the heat load for cooling below 1 K.

  2. 2015 German refrigeration and air conditioning meeting. Abstracts; Deutsche Kaelte- und Klimatagung 2015. Kurzfassungen

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2015-07-01

    The volume contains the abstracts of the 2015 German refrigeration and air conditioning meeting in 5 chapters: cryo-technology, fundamentals of materials for refrigeration engineering and heat pump technology, facilities and components for the refrigeration and heat pump technology; application of refrigeration engineering; air conditioning technology and heat pump application.

  3. Evaporation heat transfer for R-22 and R-407C refrigerant-oil mixture in a microfin tube with a U-bend

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Keumnam; Tae, Sang-Jin [Sungkyunkwan University, Suwon (D.P.R. of Korea). School of Mechanical Engineering

    2000-05-01

    Evaporation heat transfer experiments for two refrigerants, R-407C and R-22, mixed with polyol ester and mineral oils were performed in straight and U-bend sections of a microfin tube. Experimental parameters include an oil concentration varied from 0 to 5%, an inlet quality varied from 0.1 to 0.5, two mass fluxes of 219 and 400 kg m{sup -2} s{sup -1} and two heat fluxes of 10 and 20 kW m{sup -2}. Pressure drop in the test section increased by approximately 20% as the oil concentration increased from 0 to 5%. Enhancement factors decreased as oil concentration increased under inlet quality of 0.5, mass flux of 219 kg m{sup -2} s{sup -1} and heat flux of 10 kW m{sup -2}, whereas they increased under inlet quality of 0.1, mass flux of 400 kg m{sup -2} s{sup -1}, and heat flux of 20 kW m{sup -2}. The local heat transfer coefficient at the outside curvature of a U-bend was larger than that at the inside curvature of a U-bend, and the maximum value occurred at the 90{sup o} position of the U-bend. The heat transfer coefficient was larger in a region of 30 tube diameter length at the second straight section than that at the first straight section. (author)

  4. Non-linear model predictive supervisory controller for building, air handling unit with recuperator and refrigeration system with heat waste recovery

    DEFF Research Database (Denmark)

    Minko, Tomasz; Wisniewski, Rafal; Bendtsen, Jan Dimon

    2016-01-01

    . The retrieved heat excess can be stored in the water tank. For this purpose the charging and the discharging water loops has been designed. We present the non-linear model of the above described system and a non-linear model predictive supervisory controller that according to the received price signal......, occupancy information and ambient temperature minimizes the operation cost of the whole system and distributes set points to local controllers of supermarkets subsystems. We find that when reliable information about the high price period is available, it is profitable to use the refrigeration system...... to generate heat during the low price period, store it and use it to substitute the conventional heater during the high price period....

  5. Heating and melting of small icy satellites by the decay of Al-26

    International Nuclear Information System (INIS)

    Prialnik, D.; Bar-Nun, A.

    1990-01-01

    The effect of radiogenic heating due to Al-26 on the thermal evolution of small icy satellites is studied. The object is to find the extent of internal melting as a function of the satellite radius and of the initial Al-26 abundance. The implicit assumption, based on observations of young stars, is that planet and satellite accretion occurred on a time scale of about 10 to the 6th yr (comparable with the lifetime of Al-26). The icy satellites are modeled as spheres of initially amorphous ice, with chondritic abundances of K-40, Th-232, U-235, and U-238, corresponding to an ice/dust mass ratio of 1. Evolutionary calculations are carried out, spanning 4.5 x 10 to the 9th yr, for different combinations of the two free parameters. Heat transfer by subsolidus convection is neglected for these small satellites. The main conclusion is that the initial Al-26 abundance capable of melting icy bodies of satellite size to a significant extent is more than 10 times lower than that prevailing in the interstellar medium (or that inferred from the Ca-Al rich inclusions of the Allende meteorite, about 7 x 10 to the -7th by mass). 34 refs

  6. Heating and melting of small icy satellites by the decay of Al-26

    Science.gov (United States)

    Prialnik, Dina; Bar-Nun, Akiva

    1990-05-01

    The effect of radiogenic heating due to Al-26 on the thermal evolution of small icy satellites is studied. The object is to find the extent of internal melting as a function of the satellite radius and of the initial Al-26 abundance. The implicit assumption, based on observations of young stars, is that planet and satellite accretion occurred on a time scale of about 10 to the 6th yr (comparable with the lifetime of Al-26. The icy satellites are modeled as spheres of initially amorphous ice, with chondritic abundances of K-40, Th-232, U-235, and U-238, corresponding to an ice/dust mass ratio of 1. Evolutionary calculations are carried out, spanning 4.5 x 10 to the 9th yr, for different combinations of the two free parameters. Heat transfer by subsolidus convection is neglected for these small satellites. The main conclusion is that the initial Al-26 abundance capable of melting icy bodies of satellite size to a significant extent is more than 10 times lower than that prevailing in the interstellar medium (or that inferred from the Ca-Al rich inclusions of the Allende meteorite, about 7 x 10 to the -7th by mass).

  7. Two-Phase Flow in High-Heat-Flux Micro-Channel Heat Sink for Refrigeration Cooling Applications. Part 1: Micro-Channel Heat Sink for Direct Refrigeration Cooling

    Science.gov (United States)

    2008-09-01

    the two-phase mixture exiting the condenser. Throttling from high to low pressure was achieved by a manual metering valve situated upstream of the micro...channel et al. htp N4hsP) correlation (2002) kh sp = Nu kf dh’ Nuta, = const (Refer to Eqs. (1.4.6) and (1.4.7)), = 0.023Re" Prf4 f f E=1.0+6Bol6 +f(Bo)x...12.26% (318 data points) 0Id" +30%OND A ~’AAK - -30%",A- / A’ A* 10 " , , , htp ,&xp [W/M 2 K] Figure 1.4.8 Comparison of heat transfer coefficient

  8. 2014 German refrigeration and air conditioning meeting. Proceedings; Deutsche Kaelte- und Klimatagung 2014. Tagungsbericht

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2014-07-01

    The proceedings of the 2014 German refrigeration and air conditioning meeting contain contributions on the following topics: cryotechnology, fundamentals and materials for the refrigeration and heat pump technology, devices and components for the refrigeration and heat pump technology, applications of refrigeration technologies, air conditioning technology and heat pump applications, cryotechnology in biology and medicine, heat transfer and ventilation, guidelines and legal topics, refrigerant fluid - oil mixtures, control and surveillance, simulation and control, ambient air.

  9. Evaluation of Latent Heat Flux Fields from Satellites and Models during SEMAPHORE.

    Science.gov (United States)

    Bourras, Denis; Liu, W. Timothy; Eymard, Laurence; Tang, Wenqing

    2003-02-01

    Latent heat fluxes were derived from satellite observations in the region of Structure des Echanges Mer-Atmosphère, Propriétés des Hétérogénéités Océaniques: Recherche Expérimentale (SEMAPHORE), which was conducted near the Azores islands in the North Atlantic Ocean in autumn of 1993. The satellite fluxes were compared with output fields of two atmospheric circulation models and in situ measurements. The rms error of the instantaneous satellite fluxes is between 35 and 40 W m-2 and the bias is 60-85 W m-2. The large bias is mainly attributed to a bias in satellite-derived atmospheric humidity and is related to the particular shape of the vertical humidity profiles during SEMAPHORE. The bias in humidity implies that the range of estimated fluxes is smaller than the range of ship fluxes, by 34%-38%. The rms errors for fluxes from models are 30-35 W m-2, and the biases are smaller than the biases in satellite fluxes (14-18 W m-2). Two case studies suggest that the satellites detect horizontal gradients of wind speed and specific humidity if the magnitude of the gradients exceeds a detection threshold, which is 1.27 g kg-1 (100 km)-1 for specific humidity and between 0.35 and 0.82 m s-1 (30 km)-1 for wind speed. In contrast, the accuracy of the spatial gradients of bulk variables from models always varies as a function of the location and number of assimilated observations. A comparison between monthly fluxes from satellites and models reveals that satellite-derived flux anomaly fields are consistent with reanalyzed fields, whereas operational model products lack part of the mesoscale structures present in the satellite fields.

  10. Satellite-based Calibration of Heat Flux at the Ocean Surface

    Science.gov (United States)

    Barron, C. N.; Dastugue, J. M.; May, J. C.; Rowley, C. D.; Smith, S. R.; Spence, P. L.; Gremes-Cordero, S.

    2016-02-01

    Model forecasts of upper ocean heat content and variability on diurnal to daily scales are highly dependent on estimates of heat flux through the air-sea interface. Satellite remote sensing is applied to not only inform the initial ocean state but also to mitigate errors in surface heat flux and model representations affecting the distribution of heat in the upper ocean. Traditional assimilation of sea surface temperature (SST) observations re-centers ocean models at the start of each forecast cycle. Subsequent evolution depends on estimates of surface heat fluxes and upper-ocean processes over the forecast period. The COFFEE project (Calibration of Ocean Forcing with satellite Flux Estimates) endeavors to correct ocean forecast bias through a responsive error partition among surface heat flux and ocean dynamics sources. A suite of experiments in the southern California Current demonstrates a range of COFFEE capabilities, showing the impact on forecast error relative to a baseline three-dimensional variational (3DVAR) assimilation using Navy operational global or regional atmospheric forcing. COFFEE addresses satellite-calibration of surface fluxes to estimate surface error covariances and links these to the ocean interior. Experiment cases combine different levels of flux calibration with different assimilation alternatives. The cases may use the original fluxes, apply full satellite corrections during the forecast period, or extend hindcast corrections into the forecast period. Assimilation is either baseline 3DVAR or standard strong-constraint 4DVAR, with work proceeding to add a 4DVAR expanded to include a weak constraint treatment of the surface flux errors. Covariance of flux errors is estimated from the recent time series of forecast and calibrated flux terms. While the California Current examples are shown, the approach is equally applicable to other regions. These approaches within a 3DVAR application are anticipated to be useful for global and larger

  11. Recent investigations on refrigerants for magnetic refrigerators

    International Nuclear Information System (INIS)

    Hashimoto, T.

    1986-01-01

    In development of the magnetic refrigerator, an important problem is selection of magnetic materials as refrigerants. The main purpose of the present paper is to discuss the magnetic and thermal properties necessary for these refrigerants and to report recent investigations. Magnetic refrigerants can be expediently divided into two groups, one for the Carnottype magnetic refrigerator below 20 K and the other for the Ericsson-type refrigerator. The required physical properties of refrigerants in each type of the magnetic refrigerator are first discussed. And then, the results of recent investigations on the magnetic, thermal and magnetocaloric characters of several promising magnetic refrigerants are shown. Finally, a brief prospect of the magnetic refrigerants and refrigerators is given

  12. Energy saving and waste heat recovery within the refrigeration and cold storage sector in Lithuania. Final report for fact finding mission

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-02-01

    This is the final report for the Fact Finding Mission, which is the first part of the demonstration project in Energy Saving and Waste Heat recovery within the Refrigeration and Cold Storage Sector in Lithuania. The purpose of this first part of the project, The Fact Finding Mission, is the identification and recommendation of one (possibly two) companies for implementation of a demonstration project. The recommendation is based partly on the strictly technical possibilities of implementation of a demonstration project within Energy Saving and Waste Heat Recovery, but also on the interest of the companies in the implementation of this type of measures as well as their possibilities of financing. The result of The Fact Finding Mission is a recommendation for the implementation of a demonstration project at the slaughtering and meat processing company `Taurage Maistas`, for which it is estimated that there are good possibilities of implementing measures for reduction of the energy consumption and utilisation of the generated waste heat. Also, the company is considered by the authorities to be a financially well functioning company. For examples a privatisation process has already been carried out and within a few years the company has turned a deficit to a profit and increased the turnover by approx. 33%. (EG)

  13. Performance analysis of absorption heat transformer cycles using ionic liquids based on imidazolium cation as absorbents with 2,2,2-trifluoroethanol as refrigerant

    International Nuclear Information System (INIS)

    Ayou, Dereje S.; Currás, Moisés R.; Salavera, Daniel; García, Josefa; Bruno, Joan C.; Coronas, Alberto

    2014-01-01

    Highlights: • TFE + [emim][BF 4 ] (or [bmim][BF 4 ]) absorption heat transformer cycles are studied. • Influence of various operating conditions on cycle’s performance is investigated. • Performance comparisons with H 2 O + LiBr and TFE + TEGDME cycles are done. • Enthalpy data for TFE + [emim][BF 4 ] (or [bmim][BF 4 ]) liquid mixtures are calculated. • TFE + [emim][BF 4 ] (or [bmim][BF 4 ]) cycles have higher gross temperature lift (GTL). - Abstract: A detailed thermodynamic performance analysis of a single-stage absorption heat transformer and double absorption heat transformer cycles using new working pairs composed of ionic liquids (1-ethyl-3-methylimidazolium tetrafluoroborate ([emim][BF 4 ]) and 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF 4 ])) as absorbent and 2,2,2-trifluoroethanol (TFE) as refrigerant has been studied. Several performance indicators were used to evaluate and compare the performance of the cycles using the TFE + [emim][BF 4 ] and TFE + [bmim][BF 4 ] working pairs with the conventional H 2 O + LiBr and organic TFE + TEGDME working pairs. The obtained results show that the ionic liquid based working pairs are suitable candidates to replace the conventional H 2 O + LiBr working pairs in order to avoid the disadvantages associated with it mainly crystallization and corrosion and also they perform better (higher gross temperature lift) than TFE + TEGDME working pair at several operating conditions considered in this work

  14. Thermoacoustic refrigerator for space applications

    Science.gov (United States)

    Garrett, Steven L.; Adeff, Jay A.; Hofler, Thomas J.

    1993-10-01

    A new spacecraft cryocooler which uses resonant high-amplitude sound waves in inert gases to pump heat is described. The phasing of the thermoacoustic cycle is provided by thermal conduction. This 'natural' phasing allows the entire refrigerator to operate with only one moving part (the loudspeaker diaphragm). A space-qualified thermoacoustic refrigerator was flown on the Space Shuttle Discovery (STS-42) in January, 1992. It was entirely autonomous, had no sliding seals, required no lubrication, used mostly low-tolerance machined parts, and contained no expensive components. Thermoacoustics is shown to be a competitive candidate for food refrigerator/freezers and commercial/residential air conditioners. The design and performance of the Space Thermo/Acoustic Refrigerator (STAR) is described.

  15. Heat treatment and gamma radiation effects on the physical-chemical, microbiological and sensory stability of pure sugarcane juice or added with fruit juices, stored under refrigeration

    International Nuclear Information System (INIS)

    Oliveira, Aline Cristine Garcia de

    2007-01-01

    Sugarcane juice is a taste drink, energetic, no alcoholic that conserves all the nutrients in cane sugar. It was very appreciated by the Brazilian population and its production has been shown to be a highly lucrative business. This research had the following objectives: evaluate the acceptance of the consuming market and the stability of pure sugarcane juice or added with natural fruit juices, submitted of heat treatment (70 deg C/ 25 min) and/ or gamma radiation (2,5 kGy) and stored in high density polyethylene bottles, under refrigeration (5 +- 1 deg C). Sugarcane juice market test was evaluated through the application of 350 questionnaires on six Sao Paulo cities. Sugarcane juice stability was evaluated through microbiological (psychotropic count, lactic bacteria and yeasts and molds count), physical-chemical (pH, color, titratable acidity, soluble solids, ratio and polyphenoloxidase activity) and sensory (hedonic test) parameters. Centesimal composition was determined analyzing: humidity, caloric value, total carbohydrates, total and reducing sugars, lipids, proteins, ascorbic acid, ash and minerals. Sugarcane juice shelf life period was determinate ever 7 days over a period of 42 days stored under refrigeration. The data were submitted to the variance analysis and compared by Tukey's test (p<0,05). Among the 350 interviewed people, more of the half one is interested about its habitual food safe and care about street foods. Sandwiches had been cited foods as routinely consumed, followed for the sugarcane juice and 'pastel'. Among the interviewed ones, 80% had mentioned to appreciate sugarcane juice. It had not correlation between age and school age and the preference for the consumption form was with lemon juice addition. About 55% of the interviewed ones had mentioned that would more frequently consume sugarcane juice processed and packed. Sugarcane juice processing did not modify the flavor and taste of the drink. It was concluded from the sensory analyses

  16. A global analysis of the urban heat island effect based on multisensor satellite data

    Science.gov (United States)

    Xiao, J.; Frolking, S. E.; Milliman, T. E.; Schneider, A.; Friedl, M. A.

    2017-12-01

    Human population is rapidly urbanizing. In much of the world, cities are prone to hotter weather than surrounding rural areas - so-called `urban heat islands' - and this effect can have mortal consequences during heat waves. During the daytime, when the surface energy balance is driven by incoming solar radiation, the magnitude of urban warming is strongly influenced by surface albedo and the capacity to evaporate water (i.e., there is a strong relationship between vegetated land fraction and the ratio of sensible to latent heat loss or Bowen ratio). At nighttime, urban cooling is often inhibited by the thermal inertia of the built environment and anthropogenic heat exhaust from building and transportation energy use. We evaluated a suite of global remote sensing data sets representing a range of urban characteristics against MODIS-derived land-surface temperature differences between urban and surrounding rural areas. We included two new urban datasets in this analysis - MODIS-derived change in global urban extent and global urban microwave backscatter - along with several MODIS standard products and DMSP/OLS nighttime lights time series data. The global analysis spanned a range of urban characteristics that likely influence the magnitude of daytime and/or nighttime urban heat islands - urban size, population density, building density, state of development, impervious fraction, eco-climatic setting. Specifically, we developed new satellite datasets and synthesizing these with existing satellite data into a global database of urban land surface parameters, used two MODIS land surface temperature products to generate time series of daytime and nighttime urban heat island effects for 30 large cities across the globe, and empirically analyzed these data to determine specifically which remote sensing-based characterizations of global urban areas have explanatory power with regard to both daytime and nighttime urban heat islands.

  17. Performance Evaluation of a Lithium-Chloride Absorption Refrigeration and an Assessment of Its Suitability for Biomass Waste Heat

    Directory of Open Access Journals (Sweden)

    Sacha Oberweis

    2012-10-01

    Full Text Available This paper presents a computer model that will evaluate the performance of a thermo-chemical accumulator. The model is based on operational data such as temperatures and flow rates. The ultimate goal for this model is to estimate the coefficient of performance (COP of this unit when run on hot water from biomass combustion as the heat source. The outputs of the model are verified by comparing the simulation of the actual machine with published experimental data. The computed results for cooling COP are within 10% of the measured data. The simulations are all run for heat load temperatures varying between 80 °C and 110 °C. As expected, simulation results showed an increase in COP with increased heat source temperatures. The results demonstrate that the potential of combined solar and biomass combustion as a heat source for absorption cooling/heating in climates with low solar radiation can be coupled with biomass waste.

  18. Not all counterclockwise thermodynamic cycles are refrigerators

    Science.gov (United States)

    Dickerson, R. H.; Mottmann, J.

    2016-06-01

    Clockwise cycles on PV diagrams always represent heat engines. It is therefore tempting to assume that counterclockwise cycles always represent refrigerators. This common assumption is incorrect: most counterclockwise cycles cannot be refrigerators. This surprising result is explored here for quasi-static ideal gas cycles, and the necessary conditions for refrigeration cycles are clarified. Three logically self-consistent criteria can be used to determine if a counterclockwise cycle is a refrigerator. The most fundamental test compares the counterclockwise cycle with a correctly determined corresponding Carnot cycle. Other criteria we employ include a widely accepted description of the functional behavior of refrigerators, and a corollary to the second law that limits a refrigerator's coefficient of performance.

  19. Magnetocaloric refrigeration near room temperature (invited)

    International Nuclear Information System (INIS)

    Brueck, E.; Tegus, O.; Thanh, D.T.C.; Buschow, K.H.J.

    2007-01-01

    Modern society relies on readily available refrigeration. The ideal cooling machine would be a compact, solid state, silent and energy-efficient heat pump that does not require maintenance. Magnetic refrigeration has three prominent advantages compared to compressor-based refrigeration. First, there are no harmful gases involved, second it may be built more compact as the working material is a solid and third magnetic refrigerators generate much less noise. Recently, a new class of magnetic refrigerant materials for room-temperature applications was discovered. These new materials have important advantages over existing magnetic coolants: They exhibit a large magnetocaloric effect (MCE) in conjunction with a magnetic phase transition of first order. This MCE is, larger than that of Gd metal, which is used in the demonstration refrigerators built to explore the potential of this evolving technology. In the present review, we compare the different materials considering both scientific aspects and industrial applicability

  20. Satellite-based detection of global urban heat-island temperature influence

    Science.gov (United States)

    Gallo, K.P.; Adegoke, Jimmy O.; Owen, T.W.; Elvidge, C.D.

    2002-01-01

    This study utilizes a satellite-based methodology to assess the urban heat-island influence during warm season months for over 4400 stations included in the Global Historical Climatology Network of climate stations. The methodology includes local and regional satellite retrievals of an indicator of the presence green photosynthetically active vegetation at and around the stations. The difference in local and regional samples of the normalized difference vegetation index (NDVI) is used to estimate differences in mean air temperature. Stations classified as urban averaged 0.90??C (N. Hemisphere) and 0.92??C (S. Hemisphere) warmer than the surrounding environment on the basis of the NDVI-derived temperature estimates. Additionally, stations classified as rural averaged 0.19??C (N. Hemisphere) and 0.16??C (S. Hemisphere) warmer than the surrounding environment. The NDVI-derived temperature estimates were found to be in reasonable agreement with temperature differences observed between climate stations. The results suggest that satellite-derived data sets can be used to estimate the urban heat-island temperature influence on a global basis and that a more detailed analysis of rural stations and their surrounding environment may be necessary to assure that temperature trends derived from assumed rural environments are not influenced by changes in land use/land cover. Copyright 2002 by the American Geophysical Union.

  1. Refrigerating liquid prototype for LED's thermal management

    International Nuclear Information System (INIS)

    Faranda, Roberto; Guzzetti, Stefania; Lazaroiu, George Cristian; Leva, Sonia

    2012-01-01

    The heat management is the critical factor for high performance operation of LED. A new heat management application of refrigerating liquid integrated within a fabricated prototype is proposed and investigated. A series of experiments considering different heights of liquid level were performed to evaluate the heat dissipation performance and optical characteristics of the refrigerating liquid based prototype. The results reveal that the junction temperature decreases as the level of refrigerating liquid increases. The experimental results report that the refrigerating liquid reduces the junction temperature, and can positively influence the luminous radiation performances. An optimization investigation of the proposed solution was carried out to find an optimum thermal performance. The experiments indicated that refrigerating liquid cooling is a powerful way for heat dissipation of high power LEDs, and the fabrication of prototype was feasible and useful. - Highlights: ► New heat management application of refrigerating liquid on a fabricated LED prototype. ► Thermal models setup and comparison between the classical and the new solutions. ► The impact of refrigerating liquid level on LED thermal and luminous performances. ► The relationship between different levels of liquid with LED prototype performances.

  2. Research for Actively Reducing Infrared Radiation by Thermoelectric Refrigerator

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hoon; Kim, Kyomin; Kim, Woochul [Yonsei Univ., Seoul (Korea, Republic of)

    2017-03-15

    We introduced a technology for reducing infrared radiation through the active cooling of hot surfaces by using a thermoelectric refrigerator. Certain surfaces were heated by aerodynamic heating, and the heat generation processes are proposed here. We calculated the temperatures and radiations from surfaces, while using thermoelectric refrigerators to cool the surfaces. The results showed that the contrast between the radiations of certain surfaces and the ambient environments can be removed using thermoelectric refrigerators.

  3. NLP modeling for the optimization of LiBr-H_2O absorption refrigeration systems with exergy loss rate, heat transfer area, and cost as single objective functions

    International Nuclear Information System (INIS)

    Mussati, Sergio F.; Gernaey, Krist V.; Morosuk, Tatiana; Mussati, Miguel C.

    2016-01-01

    Highlights: • A NLP model is used for simultaneous optimization of sizes and operating conditions. • Total exergy loss rate and transfer area are optimized as single objective functions. • Theoretical and practical bounds for cost optimization problems are computed. • A systematic solution strategy is proposed for total annual cost optimization. • Relevance of components is ranked by heat transfer area, exergy loss rate, and cost. - Abstract: Based on a nonlinear mathematical programming model, the sizes and operating conditions of the process units of single-effect absorption refrigeration systems operating with a LiBr–H_2O solution are optimized for a specified cooling capacity by minimizing three single objective functions: the total exergy loss rate, the total heat transfer area, and the total annual cost of the system. It was found that the optimal solution obtained by minimization of the total exergy loss rate provides “theoretical” upper bounds not only for the total heat transfer area of the system but also for each process unit and all stream temperatures, while the optimal solution obtained by minimization of the total heat transfer area provides the lower bounds for these model variables, to solve a cost optimization problem. The minimization of the total exergy loss rate by varying parametrically the available total heat transfer area between these bounds was also performed, allowing to see how the optimal distribution of the available total heat transfer area among the system components, as well as the operating conditions (stream temperature, pressure, composition, and mass flow rate) and heat loads, vary qualitatively and quantitatively with increasing available total heat transfer area. These optimization results allowed to find a “practical” value of the total heat transfer area, i.e. no benefits can be obtained by increasing the available total heat transfer area above this value since the minimal total exergy loss value cannot

  4. Simulation of the Energy Saver refrigeration system

    International Nuclear Information System (INIS)

    Barton, H.R. Jr.; Nicholls, J.E.; Mulholland, G.T.

    1981-10-01

    The helium refrigeration for the Energy Saver is supplied by a Central Helium Liquefier and 24 Satellite Refrigerators installed over a 1-1/4 square mile area. An interactive, software simulator has been developed to calculate the refrigeration available from the cryogenic system over a wide range of operating conditions. The refrigeration system simulator incorporates models of the components which have been developed to quantitatively describe changes in system performance. The simulator output is presented in a real-time display which has been used to search for the optimal operating conditions of the Satellite-Central system, to examine the effect of an extended range of operating parameters and to identify equipment modifications which would improve the system performance

  5. Energy performance of supermarket refrigeration and air conditioning integrated systems working with natural refrigerants

    International Nuclear Information System (INIS)

    Cecchinato, Luca; Corradi, Marco; Minetto, Silvia

    2012-01-01

    The current trends in commercial refrigeration aim at reducing the synthetic refrigerant charge, either by minimising the internal volume of the circuit or by utilising natural refrigerants, and at energy saving. The energy efficiency of supermarkets can be improved by optimising components design, recovering thermal and refrigerating energy, adopting innovative technology solutions, integrating the HVAC system with medium temperature and low temperature refrigeration plants and, finally, reducing thermal loads on refrigerated cases. This study aims at investigating the performance of different lay-out and technological solutions where only natural refrigerants are used and at finding the potential for improving energy efficiency over the traditional systems in different climates. In the analysis, chillers and heat pumps working with ammonia or propane, medium temperature systems working with ammonia or propane and carbon dioxide as heat transfer fluid or with carbon dioxide as the refrigerant and low temperature systems working with carbon dioxide are considered and benchmarked with a state-of-the-art HFCs based plant. The most efficient investigated solution enables an annual energy saving higher than 15% with respect to the baseline solution for all the considered climates. - Highlights: ► Different natural refrigerants supermarket HVAC and R integrated systems are analysed. ► Some of the proposed solutions offer a significant benefit over the baseline one. ► Up to 18.7% energy saving is achieved in the considered climates. ► The refrigeration unit condensation by the AC chiller offers the poorest results.

  6. ACTIVATED CARBON/REFRIGERANT COMBINATIONS FOR ...

    African Journals Online (AJOL)

    ES Obe

    2001-03-01

    Mar 1, 2001 ... to solar adsorption refrigeration machines are estimated. ... heat, activated carbon/ammonia requires the use of advanced flat-plate collectors such as those with multiple ... the thermodynamic performance of zeolite-water.

  7. Influence of Oil on Refrigerant Evaporator Performance

    Science.gov (United States)

    Kim, Jong-Soo; Nagata, Karsuya; Katsuta, Masafumi; Tomosugi, Hiroyuki; Kikuchi, Kouichiro; Horichi, Toshiaki

    In vapor compression refrigeration system using oil-lubricated compressors, some amount of oil is always circulated through the system. Oil circulation can have a significant influence on the evaporator performance of automotive air conditioner which is especially required to cool quickly the car interior after a period standing in the sun. An experimental investigation was carried out an electrically heated horizontal tube to measure local heat transfer coefficients for various flow rates and heat fluxes during forced convection boiling of pure refrigerant R12 and refrigerant-oil mixtures (0-11% oil concentration by weight) and the results were compared with oil free performance. Local heat transfer coefficients increased at the region of low vapor quality by the addition of oil. On the other hand, because the oil-rich liquid film was formed on the heat transfer surface, heat transfer coefficients gradually decreased as the vapor quality became higher. Average heat transfer coefficient reached a maximum at about 4% oil concentration and this trend agreed well with the results of Green and Furse. Previous correlations, using the properties of the refrigerant-oil mixture, could not predict satisfactorily the local heat transfer coefficients data. New correlation modified by oil concentration factor was developed for predicting the corresponding heat transfer coefficient for refrigerant-oil mixture convection boiling. The maximum percent deviation between predicted and measured heat transfer coefficient was within ±30%.

  8. Analysis of energy saving performance for household refrigerator with thermal storage of condenser and evaporator

    International Nuclear Information System (INIS)

    Cheng, Wen-long; Ding, Miao; Yuan, Xu-dong; Han, Bing-Chuan

    2017-01-01

    Highlights: • A novel refrigerator with both HSC and CSE is proposed. • The operational characteristics of novel refrigerator is analyzed. • The comparison of CSE, HSC and DES refrigerators is analyzed. • DES refrigerator has a largest off-time to on-time ratio of 4.3. • DES refrigerator has the best electrical energy saving performance (32%). - Abstract: The heat transfer performances of evaporators and condensers significantly affect the efficiency of household refrigerators. For enhancing heat transfer of the condensers and evaporators, a novel dual energy storage (DES) refrigerator with both heat storage condenser (HSC) and cold storage evaporator (CSE) is proposed. The performance comparison of three kinds of energy storage refrigerators: HSC refrigerator, CSE refrigerator and DES refrigerator is analyzed by establishing dynamic simulation models. According to the simulation results, the DES refrigerator combines the advantage of HSC refrigerator and CSE refrigerator, it has more balanced operational cycle and higher evaporation pressure and temperature. The DES refrigerator shows a best energy saving performance among the three energy storage refrigerators with largest off-time to on-time ratio of 4.3 and the electrical consumption saving can reach 32%, which is greater than the sum (28%) of the other two kinds of energy storage refrigerators.

  9. Air-to-water heat pumps, business for refrigeration systems experts. Marketing of energy-efficient technology; Luft/Wasser-Waermepumpen. Ein Geschaeft fuer Kaelteanlagenbauer. Vermarktung von energieeffizienter Technik

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2009-01-15

    Many providers of refrigerating systems are already active in the private customer market offering split systems. There are less of them in the field of air-to-water heat pumps although this is also a growing market, and some producers of the air conditioning sector are already offering complete solutions. The contribution presents some sales arguments, outlines marketing tools for fitters - illustrated by the example of one provider -, and closes with a short market review. (orig.)

  10. Optimizing the Thermoacoustic Pulse Tube Refrigerator Performances

    Directory of Open Access Journals (Sweden)

    E. V. Blagin

    2014-01-01

    Full Text Available The article deals with research and optimization of the thermoacoustic pulse tube refrigerator to reach a cryogenic temperature level. The refrigerator is considered as a thermoacoustic converter based on the modified Stirling cycle with helium working fluid. A sound pressure generator runs as a compressor. Plant model comprises an inner heat exchanger, a regenerative heat exchanger, a pulse tube, hot and cold heat exchangers at its ends, an inertial tube with the throttle, and a reservoir. A model to calculate the pulse tube thermoacoustic refrigerator using the DeltaEC software package has been developed to be a basis for calculation techniques of the pulse tube refrigerator. Momentum, continuity, and energy equations for helium refrigerant are solved according to calculation algorithm taking into account the porosity of regenerator and heat exchangers. Optimization of the main geometric parameters resulted in decreasing temperature of cold heat exchanger by 41,7 K. After optimization this value became equal to 115,01 K. The following parameters have been optimized: diameters of the feeding and pulse tube and heat exchangers, regenerator, lengths of the regenerator and pulse and inertial tubes, as well as initial pressure. Besides, global minimum of temperatures has been searched at a point of local minima corresponding to the optimal values of abovementioned parameters. A global-local minima difference is 0,1%. Optimized geometric and working parameters of the thermoacoustic pulse tube refrigerator are presented.

  11. Condensation of refrigerants in horizontal, spirally grooved microfin tubes: Numerical analysis of heat transfer in the annular flow regime

    Energy Technology Data Exchange (ETDEWEB)

    Nozu, S; Honda, H

    2000-02-01

    A method is presented for estimating the condensation heat transfer coefficient in a horizontal, spirally grooved microfin tube. Based on the flow observation study performed by the authors, a laminar film condensation model in the annular flow regime is proposed. The model assumes that all the condensate flow occurs through the grooves. The condensate film is segmented into thin and thick film regions. In the thin film region formed on the fin surface, the condensate is assumed to be drained by the combined surface tension and vapor shear forces. In the thick film region formed in the groove, on the other hand, the condensate is assumed to be driven by the vapor shear force. The present and previous local heat transfer data including four fluids (CFC11, HCFC22, HCFC123, and HFCl34a) and three microfin tubes are found to agree with the present predictions to a mean absolute deviation of 15.1%.

  12. ARTI refrigerant database

    Energy Technology Data Exchange (ETDEWEB)

    Calm, J.M.

    1998-03-15

    The Refrigerant Database is an information system on alternative refrigerants, associated lubricants, and their use in air conditioning and refrigeration. It consolidates and facilitates access to thermophysical properties, compatibility, environmental, safety, application and other information. It provides corresponding information on older refrigerants, to assist manufacturers and those using alternative refrigerants, to make comparisons and determine differences. The underlying purpose is to accelerate phase out of chemical compounds of environmental concern. The database provides bibliographic citations and abstracts for publications that may be useful in research and design of air conditioning and refrigeration equipment. It also references documents addressing compatibility of refrigerants and lubricants with other materials.

  13. The effect of heat treatments on Ni43Mn42Co4Sn11 meta-magnetic shape memory alloys for magnetic refrigeration

    International Nuclear Information System (INIS)

    Bruno, Nickolaus M.; Yegin, Cengiz; Karaman, Ibrahim; Chen, Jing-Han; Ross, Joseph H.; Liu, Jian; Li, Jianguo

    2014-01-01

    The inverse magnetocaloric effect (MCE) in bulk polycrystalline and melt-spun ribbons of the Ni 43 Mn 42 Co 4 Sn 11 meta-magnetic shape memory alloy (MSMA) is investigated. The influence of several material properties on the MCE and relative cooling power (RCP) are discussed and the property combinations for optimum MCE and RCP identified for a given thermodynamic framework. These include a small slope of magnetic field vs. martensitic transformation temperature phase diagram, a narrow transformation range, low transformation thermal hysteresis and a large change in magnetization on martensitic transformation, which results in low levels of applied magnetic fields desired for repeated MCE on field cycling. The thermo-magnetic responses of the samples were measured before and after heat treatments. The heat-treated ribbons produced the most favorable MCE by exhibiting the highest magnetization change and smallest elastic energy storage through the transformation. This was attributed to the specific microstructural features, including grain size to thickness ratio and degree of L2 1 ordering. In addition, issues in the literature in determining RCP for MSMAs are discussed, and a new method to find RCP is proposed and implemented. Completely reversible magnetic-field-induced martensitic transformation cycles were used to investigate hysteresis losses relative to actual refrigeration cycles, whereby the RCP was calculated using the defined thermodynamic framework and indirectly measured entropy changes. The annealed ribbons exhibited the high RCP level of 242 J kg −1 under the applied field of 7 T compared with a theoretical maximum of 343 J kg −1 . Similar values of RCP in other MSMAs can be achievable if microstructural elastic energy storage and hysteresis loss are minimized during the transformation with the help of annealing treatments

  14. Space chamber experiments of ohmic heating by high power microwave from the solar power satellite

    Energy Technology Data Exchange (ETDEWEB)

    Kaya, N.; Matsumoto, H.

    1981-12-01

    It is quantitatively predicted that a high power microwave from the Solar Power Satellite (SPS) nonlinearly interacts with the ionospheric plasma. The possible nonlinear interactions are ohmic heating, self-focusing and parametric instabilities. A rocket experiment called MINIX (Microwave-Ionosphere Nonlinear Interaction Experiment) has been attempted to examine these effects, but is note reported here. In parallel to the rocket experiment, a laboratory experiment in a space plasma simulation chamber has been carried out in order to examine ohmic heating in detail and to develop a system of the rocket experiment. Interesting results were observed and these results were utilized to revise the system of the rocket experiments. A significant microwave heating of plasma up to 150% temperature increase was observed with little electron density decrease. It was shown that the temperature increase is not due to the RF breakdown but to the ohmic heating in the simulated ionospheric plasma. These microwave effects have to be taken into account in the SPS Project in the future.

  15. Solar-Powered Refrigeration System

    Science.gov (United States)

    Ewert, Michael K. (Inventor); Bergeron, David J., III (Inventor)

    2002-01-01

    A solar powered vapor compression refrigeration system is made practicable with thermal storage and novel control techniques. In one embodiment, the refrigeration system includes a photovoltaic panel, a variable speed compressor, an insulated enclosure, and a thermal reservoir. The photovoltaic (PV) panel converts sunlight into DC (direct current) electrical power. The DC electrical power drives a compressor that circulates refrigerant through a vapor compression refrigeration loop to extract heat from the insulated enclosure. The thermal reservoir is situated inside the insulated enclosure and includes a phase change material. As heat is extracted from the insulated enclosure, the phase change material is frozen, and thereafter is able to act as a heat sink to maintain the temperature of the insulated enclosure in the absence of sunlight. The conversion of solar power into stored thermal energy is optimized by a compressor control method that effectively maximizes the compressor's usage of available energy. A capacitor is provided to smooth the power voltage and to provide additional current during compressor start-up. A controller monitors the rate of change of the smoothed power voltage to determine if the compressor is operating below or above the available power maximum, and adjusts the compressor speed accordingly. In this manner, the compressor operation is adjusted to convert substantially all available solar power into stored thermal energy.

  16. ARTI refrigerant database

    Energy Technology Data Exchange (ETDEWEB)

    Calm, J.M. [Calm (James M.), Great Falls, VA (United States)

    1999-01-01

    The Refrigerant Database is an information system on alternative refrigerants, associated lubricants, and their use in air conditioning and refrigeration. It consolidates and facilities access to property, compatibility, environmental, safety, application and other information. It provides corresponding information on older refrigerants, to assist manufacturers and those using alternative refrigerants, to make comparisons and determine differences. The underlying purpose is to accelerate phase out of chemical compounds of environmental concern.

  17. ARTI refrigerant database

    Energy Technology Data Exchange (ETDEWEB)

    Calm, J.M.

    1996-07-01

    The Refrigerant Database is an information system on alternative refrigerants, associated lubricants, and their use in air conditioning and refrigeration. It consolidates and facilitates access to property, compatibility, environmental, safety, application and other information. It provides corresponding information on older refrigerants, to assist manufacturers and those using alternative refrigerants, to make comparisons and determine differences. The underlying purpose is to accelerate phase out of chemical compounds of environmental concern.

  18. ARTI refrigerant database

    Energy Technology Data Exchange (ETDEWEB)

    Calm, J.M.

    1996-11-15

    The Refrigerant Database is an information system on alternative refrigerants, associated lubricants, and their use in air conditioning and refrigeration. It consolidates and facilitates access to property, compatibility, environmental, safety, application and other information. It provides corresponding information on older refrigerants, to assist manufacturers and those using alternative refrigerants, to make comparisons and determine differences. The underlying purpose is to accelerate phase out of chemical compounds of environmental concern.

  19. Simulation of absorption refrigeration system for automobile application

    Directory of Open Access Journals (Sweden)

    Ramanathan Anand

    2008-01-01

    Full Text Available An automotive air-conditioning system based on absorption refrigeration cycle has been simulated. This waste heat driven vapor absorption refrigeration system is one alternate to the currently used vapour compression refrigeration system for automotive air-conditioning. Performance analysis of vapor absorption refrigeration system has been done by developing a steady-state simulation model to find the limitation of the proposed system. The water-lithium bromide pair is used as a working mixture for its favorable thermodynamic and transport properties compared to the conventional refrigerants utilized in vapor compression refrigeration applications. The pump power required for the proposed vapor absorption refrigeration system was found lesser than the power required to operate the compressor used in the conventional vapor compression refrigeration system. A possible arrangement of the absorption system for automobile application is proposed.

  20. Experimental study of the use of refrigeration systems as cooling and heating systems in the production process of the VCO

    Science.gov (United States)

    Mulawarman, AANB; Arsana, M. E.; Temaja, I. W.; Sukadana, IBP

    2018-01-01

    Coconut oil extracted from the coconut milk obtained from fresh coconuts s often called virgin coconut oil (VCO). VCO is beneficial to health as an anti-oxidant and can lower HDL cholesterol in the blood while increasing blood LDL levels. In Indonesia most of VCO being produced on a small scale of home industries. Its production capacity still needs to be increased by improving production processes and implementing an appropriate technology accordingly. This research aims to conduct a study on making small-scale production machinery needed to produce VCO with reduced production time and improved quality of VCO in accordance with ISO 7381 quality criteria. The experimental results of the VCO machine has been develop and tested show good Coefficient of Performance of the system in amount of 3.93 and 2.8 for heating and cooling system respectively. Temperature of the VCO cooling chamber can be maintained in the range of 8°C to 10°C, as well as for heating, the reactor temperature can be maintained from 39°C to 42°C. The expected goal of this research developing a prototype of VCO production machine was done with ability to provide more efficient production process able to increase volume of VCO result by 23%.

  1. Relationship between composition of mixture charged and that in circulation in an auto refrigerant cascade and a J-T refrigerator operating in liquid refrigerant supply mode

    Science.gov (United States)

    Sreenivas, Bura; Nayak, H. Gurudath; Venkatarathnam, G.

    2017-01-01

    The composition of the refrigerant mixture in circulation during steady state operation of J-T and allied refrigerators is not the same as that charged due to liquid hold up in the heat exchangers and phase separators, as well as the differential solubility of different refrigerant components in the compressor lubricating oil. The performance of refrigerators/liquefiers operating on mixed refrigerant cycles is dependent on the mixture composition. It is therefore important to charge the right mixture that results in an optimum composition in circulation during steady state operation. The relationship between the charged and circulating composition has been experimentally studied in a J-T refrigerator operating in the liquid refrigerant supply (LRS) mode and an auto refrigerant cascade refrigerator (with a phase separator) operating in the gas refrigerant supply (GRS) mode. The results of the study are presented in this work. The results show that the method presented earlier for J-T refrigerators operating in GRS mode is also applicable in the case of refrigerators studied in this work.

  2. A review on adsorption refrigeration technology and adsorption deterioration in physical adsorption systems

    Energy Technology Data Exchange (ETDEWEB)

    Wang, D.C.; Li, Y.H. [College of Electromechanical Engineering, Qingdao University, 308 Ningxia Road, Qingdao 266071 (China); Laboratory of Fiber Materials and Modern Textile, the Growing Base for State Key Laboratory, Qingdao University, 308 Ningxia Road, Qingdao 266071 (China); Li, D.; Zhang, J.P. [College of Electromechanical Engineering, Qingdao University, 308 Ningxia Road, Qingdao 266071 (China); Xia, Y.Z. [Laboratory of Fiber Materials and Modern Textile, the Growing Base for State Key Laboratory, Qingdao University, 308 Ningxia Road, Qingdao 266071 (China)

    2010-01-15

    As one kind of environmentally friendly refrigeration, the adsorption refrigeration has attracted many attentions in resent decades. This paper introduces the researches of adsorption refrigeration systems with the commonly used working pairs, advanced adsorption cycles, heat and mass transfer enhancement and attempts of adsorption refrigeration applications. Poor heat and mass transfer problem is a bottleneck to prevent the improvements of the adsorption refrigeration technique. Two ways to enhance the heat and mass transfer are discussed in this paper. The adsorption deterioration of adsorbent, another obstacle to physical adsorption refrigeration applications, is also pointed out. And the possible reasons and the possible methods are analyzed. (author)

  3. Satellite and ground-based sensors for the Urban Heat Island analysis in the city of Rome

    DEFF Research Database (Denmark)

    Fabrizi, Roberto; Bonafoni, Stefania; Biondi, Riccardo

    2010-01-01

    In this work, the trend of the Urban Heat Island (UHI) of Rome is analyzed by both ground-based weather stations and a satellite-based infrared sensor. First, we have developed a suitable algorithm employing satellite brightness temperatures for the estimation of the air temperature belonging...... and nighttime scenes taken between 2003 and 2006 have been processed. Analysis of the Canopy Layer Heat Island (CLHI) during summer months reveals a mean growth in magnitude of 3-4 K during nighttime and a negative or almost zero CLHI intensity during daytime, confirmed by the weather stations. © 2010...... by the authors; licensee MDPI, Basel, Switzerland. Keyword: Thermal pollution,Summer months,Advanced-along track scanning radiometers,Urban heat island,Remote sensing,Canopy layer,Atmospheric temperature,Ground based sensors,Weather information services,Satellite remote sensing,Infra-red sensor,Weather stations...

  4. THE RESULTS OF THE STUDY BOILING POINT OUT OZONE-SAFE REFRIGERANT R410A IN THE EVAPORATORS OF REFRIGERATING MACHINES

    Directory of Open Access Journals (Sweden)

    V. G. Bukin

    2012-01-01

    Full Text Available The results of experimental research boiling heat transfer of ozone-friendly R410A refrigerant in evaporators machines and the possibility of its use in place of the prohibited refrigerant R22.

  5. Operating Manual of Helium Refrigerator (Rev. 2)

    Energy Technology Data Exchange (ETDEWEB)

    Song, K.M.; Son, S.H.; Kim, K.S.; Lee, S.K.; Kim, M.S. [Korea Electric Power Research Institute, Taejon (Korea)

    2002-07-01

    A helium refrigerator was installed as a supplier of 20K cold helium to the cryogenic distillation system of WTRF pilot plant. The operating procedures of the helium refrigerator, helium compressor and auxiliary apparatus are described for the safety and efficient operation in this manual. The function of the helium refrigerator is to remove the impurities from the compressed helium of about 250psig, to cool down the helium from ambient temperature to 20K through the heat exchanger and expansion engine and to transfer the cold helium to the cryogenic distillation system. For the smoothly operation of helium refrigerator, the preparation, the start-up, the cool-down and the shut-down of the helium refrigerator are described in this operating manual. (author). 3 refs., 14 tabs.

  6. Review of magnetic refrigeration system as alternative to conventional refrigeration system

    Science.gov (United States)

    Mezaal, N. A.; Osintsev, K. V.; Zhirgalova, T. B.

    2017-10-01

    The refrigeration system is one of the most important systems in industry. Developers are constantly seeking for how to avoid the damage to the environment. Magnetic refrigeration is an emerging, environment-friendly technology based on a magnetic solid that acts as a refrigerant by magneto-caloric effect (MCE). In the case of ferromagnetic materials, MCE warms as the magnetic moments of the atom are aligned by the application of a magnetic field. There are two types of magnetic phase changes that may occur at the Curie point: first order magnetic transition (FOMT) and second order magnetic transition (SOMT). The reference cycle for magnetic refrigeration is AMR (Active Magnetic Regenerative cycle), where the magnetic material matrix works both as a refrigerating medium and as a heat regenerating medium, while the fluid flowing in the porous matrix works as a heat transfer medium. Regeneration can be accomplished by blowing a heat transfer fluid in a reciprocating fashion through the regenerator made of magnetocaloric material that is alternately magnetized and demagnetized. Many magnetic refrigeration prototypes with different designs and software models have been built in different parts of the world. In this paper, the authors try to shed light on the magnetic refrigeration and show its effectiveness compared with conventional refrigeration methods.

  7. Refrigeration generation using expander-generator units

    Science.gov (United States)

    Klimenko, A. V.; Agababov, V. S.; Koryagin, A. V.; Baidakova, Yu. O.

    2016-05-01

    The problems of using the expander-generator unit (EGU) to generate refrigeration, along with electricity were considered. It is shown that, on the level of the temperatures of refrigeration flows using the EGU, one can provide the refrigeration supply of the different consumers: ventilation and air conditioning plants and industrial refrigerators and freezers. The analysis of influence of process parameters on the cooling power of the EGU, which depends on the parameters of the gas expansion process in the expander and temperatures of cooled environment, was carried out. The schematic diagram of refrigeration generation plant based on EGU is presented. The features and advantages of EGU to generate refrigeration compared with thermotransformer of steam compressive and absorption types were shown, namely: there is no need to use the energy generated by burning fuel to operate the EGU; beneficial use of the heat delivered to gas from the flow being cooled in equipment operating on gas; energy production along with refrigeration generation, which makes it possible to create, using EGU, the trigeneration plants without using the energy power equipment. It is shown that the level of the temperatures of refrigeration flows, which can be obtained by using the EGU on existing technological decompression stations of the transported gas, allows providing the refrigeration supply of various consumers. The information that the refrigeration capacity of an expander-generator unit not only depends on the parameters of the process of expansion of gas flowing in the expander (flow rate, temperatures and pressures at the inlet and outlet) but it is also determined by the temperature needed for a consumer and the initial temperature of the flow of the refrigeration-carrier being cooled. The conclusion was made that the expander-generator units can be used to create trigeneration plants both at major power plants and at small energy.

  8. Method and refrigerants for replacing existing refrigerants in centrifugal compressors

    International Nuclear Information System (INIS)

    Kopko, W.L.

    1991-01-01

    This patent describes a method for replacing an existing refrigerant in a centrifugal compressor. It comprises selecting a desired impeller Mach number for the centrifugal compressor; selecting a base refrigerant constituent; combining at least one additive refrigerant constituent with the base refrigerant constituent to form a replacement refrigerant having at least one physical or chemical property different from the existing refrigerant and substantially providing the desired impeller Mach number in the centrifugal compressor; and replacing the existing refrigerant with the replacement refrigerant

  9. Environmentally benign working pairs for adsorption refrigeration

    International Nuclear Information System (INIS)

    Cui Qun; Tao Gang; Chen Haijun; Guo Xinyue; Yao Huqing

    2005-01-01

    This paper begins from adsorption working pairs: water and ethanol were selected as refrigerants; 13x molecular sieve, silica gel, activated carbon, adsorbent NA and NB, proposed by authors, were selected as adsorbents, and the performance of adsorption working pairs in adsorption refrigeration cycle was studied. The adsorption isotherms of adsorbents (NA and NB) were obtained by high-vacuum gravimetric method. Desorption properties of adsorbents were analyzed and compared by thermal analysis method. The performance of adsorption refrigeration was studied on simulation device of adsorption refrigeration cycle. After presentation of adsorption isotherms, the thermodynamic performance for their use in adsorption refrigeration system was calculated. The results show: (1) the maximum adsorption capacity of water on adsorbent NA reaches 0.7 kg/kg, and the maximum adsorption capacity of ethanol on adsorbent NB is 0.68 kg/kg, which is three times that of ethanol on activated carbon, (2) the refrigeration capacity of NA-water working pair is 922 kJ/kg, the refrigeration capacity of NB-ethanol is 2.4 times that of activated carbon-methanol, (3) as environmental friendly and no public hazard adsorption working pair, NA-H 2 O and NB-ethanol can substitute activated carbon-methanol in adsorption refrigeration system using low-grade heat source

  10. Precipitation and Latent Heating Distributions from Satellite Passive Microwave Radiometry. Part 1; Improved Method and Uncertainties

    Science.gov (United States)

    Olson, William S.; Kummerow, Christian D.; Yang, Song; Petty, Grant W.; Tao, Wei-Kuo; Bell, Thomas L.; Braun, Scott A.; Wang, Yansen; Lang, Stephen E.; Johnson, Daniel E.; hide

    2006-01-01

    A revised Bayesian algorithm for estimating surface rain rate, convective rain proportion, and latent heating profiles from satellite-borne passive microwave radiometer observations over ocean backgrounds is described. The algorithm searches a large database of cloud-radiative model simulations to find cloud profiles that are radiatively consistent with a given set of microwave radiance measurements. The properties of these radiatively consistent profiles are then composited to obtain best estimates of the observed properties. The revised algorithm is supported by an expanded and more physically consistent database of cloud-radiative model simulations. The algorithm also features a better quantification of the convective and nonconvective contributions to total rainfall, a new geographic database, and an improved representation of background radiances in rain-free regions. Bias and random error estimates are derived from applications of the algorithm to synthetic radiance data, based upon a subset of cloud-resolving model simulations, and from the Bayesian formulation itself. Synthetic rain-rate and latent heating estimates exhibit a trend of high (low) bias for low (high) retrieved values. The Bayesian estimates of random error are propagated to represent errors at coarser time and space resolutions, based upon applications of the algorithm to TRMM Microwave Imager (TMI) data. Errors in TMI instantaneous rain-rate estimates at 0.5 -resolution range from approximately 50% at 1 mm/h to 20% at 14 mm/h. Errors in collocated spaceborne radar rain-rate estimates are roughly 50%-80% of the TMI errors at this resolution. The estimated algorithm random error in TMI rain rates at monthly, 2.5deg resolution is relatively small (less than 6% at 5 mm day.1) in comparison with the random error resulting from infrequent satellite temporal sampling (8%-35% at the same rain rate). Percentage errors resulting from sampling decrease with increasing rain rate, and sampling errors in

  11. Refrigeration system having standing wave compressor

    Science.gov (United States)

    Lucas, Timothy S.

    1992-01-01

    A compression-evaporation refrigeration system, wherein gaseous compression of the refrigerant is provided by a standing wave compressor. The standing wave compressor is modified so as to provide a separate subcooling system for the refrigerant, so that efficiency losses due to flashing are reduced. Subcooling occurs when heat exchange is provided between the refrigerant and a heat pumping surface, which is exposed to the standing acoustic wave within the standing wave compressor. A variable capacity and variable discharge pressure for the standing wave compressor is provided. A control circuit simultaneously varies the capacity and discharge pressure in response to changing operating conditions, thereby maintaining the minimum discharge pressure needed for condensation to occur at any time. Thus, the power consumption of the standing wave compressor is reduced and system efficiency is improved.

  12. Auto-refrigerating cascade for superconducting applications

    International Nuclear Information System (INIS)

    Forrest, S.M.; Hall, P.H.; Missimer, D.J.

    1987-01-01

    Extremely low temperatures, in the range of 230 to 90 K, are achieved in a single circuit compression refrigeration system operated by a conventional compressor. The system relies upon a series of intermediate cooling stages. The refrigerant is a mixture and the system employs fractional condensation, distillation, phase separation and intermediate heat transfer. Each stage includes the steps of withdrawing a portion of the liquid condensate from the compressed vapor-liquid refrigerant mixture which enters the stage. The withdrawn condensate is then throttled to a lower pressure and is mixed with the refrigerant being recycled to the compressor from the final evaporator. Evaporating the throttled condensate absorbs heat from and at least partially condenses the compressed uncondensed vapor in the compressed mixture

  13. Two-phase flow in refrigeration systems

    CERN Document Server

    Gu, Junjie; Gan, Zhongxue

    2013-01-01

    Two-Phase Flow in Refrigeration Systems presents recent developments from the authors' extensive research programs on two-phase flow in refrigeration systems. This book covers advanced mass and heat transfer and vapor compression refrigeration systems and shows how the performance of an automotive air-conditioning system is affected through results obtained experimentally and theoretically, specifically with consideration of two-phase flow and oil concentration. The book is ideal for university postgraduate students as a textbook, researchers and professors as an academic reference book, and b

  14. Cogeneration in breweries analysis and simulation of systems for simultaneous generation of power, heat and refrigeration using natural gas; Sistemas de refrigeracao a partir da cogeracao: analise e simulacao de propostas para o caso de cervejarias utilizando gas natural

    Energy Technology Data Exchange (ETDEWEB)

    Gallego, Antonio Garrido

    1998-07-01

    The present work analyses some proposals of cogeneration systems for the simultaneous generation of power, heat and refrigeration in a brewery. The requirements of steam, refrigeration and electricity, as well as the production of beer in a plant of the Antarctica Company, located in Jaguariuna - SP were collected monthly for the year of 1997. Three conceptions of systems using two gas turbines with heat recovery steam generator were then proposed to meet the surveyed demand. The proposals differ in the refrigeration system: the first one uses a traditional ammonia compression system while the second uses an ammonia absorption system, the third proposal is a combination of the compression and absorption systems. These proposals are compared to the present configuration which purchases electricity from the Public Utility for power and refrigeration (using an ammonia compression)system, and fuel oil to generate steam for process heat. The technical, economical and environmental feasibility of the proposals, as well as of the present configuration are discussed on the basis of mass balances, energy balances (first law of Thermodynamics), exergy fluxes (second law analysis), operational and capital cost, based on simulation of the performance of each configuration proposed to meet the monthly electricity, steam and refrigeration requirements for the referred plant. The turbines were chosen so as to meet the peek energy demand of the plant and two cases were simulated for each proposal: turbine operational meets only the demand of the plant and turbine operates at full load, selling electricity for the Public utility. Results obtained show that the current operational costs are higher than any of the proposals presented. The high capital costs of the proposals, though,make them less interesting financially. The simulation of the case of excess electricity to the Public Utility is very attractive, considering the cost of natural gas 3,38 U$/M btu and the fare of 40 U

  15. improvement to the design of a solid absorption solar refrigerator

    African Journals Online (AJOL)

    user

    on the coupling of auxiliary heating systems to the solar powered refrigerator. ... the efficiency, developing a field prototype and providing auxiliary heating to the ... of a selective surface for the collector plate, air leakages and low absorber ...

  16. Transition to New Refrigerants

    Science.gov (United States)

    Overview page provides information on the refrigerants that motor vehicle air conditioners have used over time, with information on environmental impacts, refrigerant fitting sizes, label colors, and alternatives to ozone-depleting substances.

  17. ARTI Refrigerant Database

    Energy Technology Data Exchange (ETDEWEB)

    Calm, J.M. [Calm (James M.), Great Falls, VA (United States)

    1994-05-27

    The Refrigerant Database consolidates and facilitates access to information to assist industry in developing equipment using alternative refrigerants. The underlying purpose is to accelerate phase out of chemical compounds of environmental concern.

  18. Satellite and Ground-Based Sensors for the Urban Heat Island Analysis in the City of Rome

    Directory of Open Access Journals (Sweden)

    Roberto Fabrizi

    2010-05-01

    Full Text Available In this work, the trend of the Urban Heat Island (UHI of Rome is analyzed by both ground-based weather stations and a satellite-based infrared sensor. First, we have developed a suitable algorithm employing satellite brightness temperatures for the estimation of the air temperature belonging to the layer of air closest to the surface. UHI spatial characteristics have been assessed using air temperatures measured by both weather stations and brightness temperature maps from the Advanced Along Track Scanning Radiometer (AATSR on board ENVISAT polar-orbiting satellite. In total, 634 daytime and nighttime scenes taken between 2003 and 2006 have been processed. Analysis of the Canopy Layer Heat Island (CLHI during summer months reveals a mean growth in magnitude of 3–4 K during nighttime and a negative or almost zero CLHI intensity during daytime, confirmed by the weather stations.

  19. Flow patterns during refrigerant condensation in smooth and enhanced tubes

    OpenAIRE

    2009-01-01

    M.Ing. The Montreal Protocol led to the phasing-out of ozone layer depleting refrigerants and replacing them with more environmentally friendly refrigerants, which in many cases caused heat transfer degradation in heat exchanger equipment. To make up for the heat transfer degradation, there was a need for the application of heat transfer enhancement techniques. One such technique is the use of micro-fin tubes as opposed to traditional smooth tubes. The purpose of this study is to develop a...

  20. Ultimate refrigerating conditions, behavior turning and a thermodynamic analysis for absorption–compression hybrid refrigeration cycle

    International Nuclear Information System (INIS)

    Zheng Danxing; Meng Xuelin

    2012-01-01

    Highlights: ► Two novel fundamental concepts of the absorption refrigeration cycle were proposed. ► The interaction mechanism of compressor pressure increasing with other key-parameters was investigated. ► A set of optimal operating condition of hybrid refrigeration cycle was found. ► A simulation and investigation for R134a-DMF hybrid refrigeration cycle was performed. - Abstract: The absorption–compression hybrid refrigeration cycle has been considered as an effective approach to reduce the mechanical work consumption by using low-grade heat, such as solar energy. This work aims at studying the thermodynamic mechanism of the hybrid refrigeration cycle. Two fundamental concepts have been proposed, which are the ultimate refrigerating temperature (or the ultimate temperature lift) and the behavior turning. On the basis of that, the interaction mechanism of compressor pressure increasing with other key-parameters and the impact of compressor pressure increasing on the cycle performance have been investigated. The key-parameters include the concentration difference, the circulation ratio of working fluid, etc. The work points out that the hybrid refrigeration cycle performance varies with the change of compressor outlet pressure and depends on which one achieves dominance in the hybrid refrigeration cycle, the absorption sub-system or the compression sub-system. The behavior turning point during parameters changing corresponds to a maximum value of the heat powered coefficient of performance. In this case, the hybrid refrigeration cycle performance is optimal because the low-grade heat utilization is the most effective. In addition, to validate the theoretical analysis, a solar hybrid refrigeration cycle with R134a–DMF as working pair was simulated. The Peng–Robinson equation of state was adopted to calculate thermophysical properties when the reliability assessment of the prediction models on the available literature data of R134a–DMF system had been

  1. Theoretical study and design of a low-grade heat-driven pilot ejector refrigeration machine operating with butane and isobutane and intended for cooling of gas transported in a gas-main pipeline

    KAUST Repository

    Petrenko, V.O.

    2011-11-01

    This paper describes the construction and performance of a novel combined system intended for natural gas transportation and power production, and for cooling of gas transported in a gas-main pipeline. The proposed system includes a gas turbine compressor, a combined electrogenerating plant and an ejector refrigeration unit operating with a hydrocarbon refrigerant. The combined electrogenerating plant consists of a high-temperature steam-power cycle and a low-temperature hydrocarbon vapor power cycle, which together comprise a binary vapor system. The combined system is designed for the highest possible effectiveness of power generation and could find wide application in gas-transmission systems of gas-main pipelines. Application of the proposed system would enable year-round power generation and provide cooling of natural gas during periods of high ambient temperature operation. This paper presents the main results of a theoretical study and design performance specifications of a low-grade heat-driven pilot ejector refrigeration machine operating with butane and isobutane. © 2010 Elsevier Ltd and IIR. All rights reserved.

  2. Thermal flow regulator of refrigerant

    International Nuclear Information System (INIS)

    Dubinskij, S.I.; Savchenko, A.G.; Suplin, V.Z.

    1988-01-01

    A thermal flow regulator of refrigerant for helium flow-type temperature-controlled cryostats based on controlling the channel hydraulic resistance due to variation of the flow density and viscosity during liquid helium transformation into the gaseous state. Behind the regulator both two-phase flow and a heated gas can be produced. The regulator resolution is (7-15)x10 -4 l/mW of liquid helium

  3. Environment-friendly heat supply with natural refrigerants. Large heat pumps use industrial waste heat and waste water; Umweltschonende Waermeversorgung mit natuerlichen Kaeltemitteln. Grosswaermepumpen nutzen industrielle Abwaerme und Abwaesser

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2011-01-15

    Everywhere, where industrial processes occur or coldness is produced, simultaneously heat is produced. While many private houses use geothermal energy or ambient air for the production of heat, waste water and waste heat prove to be optimal energy sources for the industrial need due to higher output temperatures. By means of large heat pumps the residual heat is used for heating or the supply of hot water for example in local heat supply grids and makes an important contribution to climate protection.

  4. Magnetic refrigerator for hydrogen liquefaction

    Energy Technology Data Exchange (ETDEWEB)

    Numazawa, T [National Institute for Materials Science, Tsukuba (Japan); Kamlya, K. [Japan Atomic Energy Agency, Naka (Japan); Utaki, T. [Osaka University, Osaka (Japan); Matsumoto, K. [Kanazawa University, Kanazawa (Japan)

    2013-06-15

    This paper reviews the development status of magnetic refrigeration system for hydrogen liquefaction. There is no doubt that hydrogen is one of most important energy sources in the near future. In particular, liquid hydrogen can be utilized for infrastructure construction consisting of storage and transportation. Liquid hydrogen is in cryogenic temperatures and therefore high efficient liquefaction method must be studied. Magnetic refrigeration which uses the magneto-caloric effect has potential to realize not only the higher liquefaction efficiency > 50 %, but also to be environmentally friendly and cost effective. Our hydrogen magnetic refrigeration system consists of Carnot cycle for liquefaction stage and AMR (active magnetic regenerator) cycle for precooling stages. For the Carnot cycle, we develop the high efficient system > 80 % liquefaction efficiency by using the heat pipe. For the AMR cycle, we studied two kinds of displacer systems, which transferred the working fluid. We confirmed the AMR effect with the cooling temperature span of 12 K for 1.8 T of the magnetic field and 6 second of the cycle. By using the simulation, we estimate the total efficiency of the hydrogen liquefaction plant for 10 kg/day. A FOM of 0.47 is obtained in the magnetic refrigeration system operation temperature between 20 K and 77 K including LN2 work input.

  5. Assessment of ionospheric Joule heating by GUMICS-4 MHD simulation, AMIE, and satellite-based statistics: towards a synthesis

    Directory of Open Access Journals (Sweden)

    M. Palmroth

    2005-09-01

    Full Text Available We investigate the Northern Hemisphere Joule heating from several observational and computational sources with the purpose of calibrating a previously identified functional dependence between solar wind parameters and ionospheric total energy consumption computed from a global magnetohydrodynamic (MHD simulation (Grand Unified Magnetosphere Ionosphere Coupling Simulation, GUMICS-4. In this paper, the calibration focuses on determining the amount and temporal characteristics of Northern Hemisphere Joule heating. Joule heating during a substorm is estimated from global observations, including electric fields provided by Super Dual Auroral Network (SuperDARN and Pedersen conductances given by the ultraviolet (UV and X-ray imagers on board the Polar satellite. Furthermore, Joule heating is assessed from several activity index proxies, large statistical surveys, assimilative data methods (AMIE, and the global MHD simulation GUMICS-4. We show that the temporal and spatial variation of the Joule heating computed from the GUMICS-4 simulation is consistent with observational and statistical methods. However, the different observational methods do not give a consistent estimate for the magnitude of the global Joule heating. We suggest that multiplying the GUMICS-4 total Joule heating by a factor of 10 approximates the observed Joule heating reasonably well. The lesser amount of Joule heating in GUMICS-4 is essentially caused by weaker Region 2 currents and polar cap potentials. We also show by theoretical arguments that multiplying independent measurements of averaged electric fields and Pedersen conductances yields an overestimation of Joule heating.

    Keywords. Ionosphere (Auroral ionosphere; Modeling and forecasting; Electric fields and currents

  6. Modeling and calculation of open carbon dioxide refrigeration system

    International Nuclear Information System (INIS)

    Cai, Yufei; Zhu, Chunling; Jiang, Yanlong; Shi, Hong

    2015-01-01

    Highlights: • A model of open refrigeration system is developed. • The state of CO 2 has great effect on Refrigeration capacity loss by heat transfer. • Refrigeration capacity loss by remaining CO 2 has little relation to the state of CO 2 . • Calculation results are in agreement with the test results. - Abstract: Based on the analysis of the properties of carbon dioxide, an open carbon dioxide refrigeration system is proposed, which is responsible for the situation without external electricity unit. A model of open refrigeration system is developed, and the relationship between the storage environment of carbon dioxide and refrigeration capacity is conducted. Meanwhile, a test platform is developed to simulation the performance of the open carbon dioxide refrigeration system. By comparing the theoretical calculations and the experimental results, several conclusions are obtained as follows: refrigeration capacity loss by heat transfer in supercritical state is much more than that in two-phase region and the refrigeration capacity loss by remaining carbon dioxide has little relation to the state of carbon dioxide. The results will be helpful to the use of open carbon dioxide refrigeration

  7. A Satellite-Derived Climatological Analysis of Urban Heat Island over Shanghai during 2000–2013

    Directory of Open Access Journals (Sweden)

    Weijiao Huang

    2017-06-01

    Full Text Available The urban heat island is generally conducted based on ground observations of air temperature and remotely sensing of land surface temperature (LST. Satellite remotely sensed LST has the advantages of global coverage and consistent periodicity, which overcomes the weakness of ground observations related to sparse distributions and costs. For human related studies and urban climatology, canopy layer urban heat island (CUHI based on air temperatures is extremely important. This study has employed remote sensing methodology to produce monthly CUHI climatology maps during the period 2000–2013, revealing the spatiotemporal characteristics of daytime and nighttime CUHI during this period of rapid urbanization in Shanghai. Using stepwise linear regression, daytime and nighttime air temperatures at the four overpass times of Terra/Aqua were estimated based on time series of Terra/Aqua-MODIS LST and other auxiliary variables including enhanced vegetation index, normalized difference water index, solar zenith angle and distance to coast. The validation results indicate that the models produced an accuracy of 1.6–2.6 °C RMSE for the four overpass times of Terra/Aqua. The models based on Terra LST showed higher accuracy than those based on Aqua LST, and nighttime air temperature estimation had higher accuracy than daytime. The seasonal analysis shows daytime CUHI is strongest in summer and weakest in winter, while nighttime CUHI is weakest in summer and strongest in autumn. The annual mean daytime CUHI during 2000–2013 is 1.0 and 2.2 °C for Terra and Aqua overpass, respectively. The annual mean nighttime CUHI is about 1.0 °C for both Terra and Aqua overpass. The resultant CUHI climatology maps provide a spatiotemporal quantification of CUHI with emphasis on temperature gradients. This study has provided information of relevance to urban planners and environmental managers for assessing and monitoring urban thermal environments which are constantly

  8. A miniaturized plastic dilution refrigerator

    International Nuclear Information System (INIS)

    Bindilatti, V.; Oliveira, N.F.Jr.; Martin, R.V.; Frossati, G.

    1996-01-01

    We have built and tested a miniaturized dilution refrigerator, completely contained (still, heat exchanger and mixing chamber) inside a plastic (PVC) tube of 10 mm diameter and 170 mm length. With a 25 cm 2 CuNi heat exchanger, it reached temperatures below 50 mK, for circulation rates below 70 μmol/s. The cooling power at 100 mK and 63 μmol/s was 45 μW. The experimental space could accommodate samples up to 6 mm in diameter. (author)

  9. TREND ASSESSMENT OF SPATIO-TEMPORAL CHANGE OF TEHRAN HEAT ISLAND USING SATELLITE IMAGES

    Directory of Open Access Journals (Sweden)

    M. R. Saradjian

    2015-12-01

    Full Text Available Numerous investigations on Urban Heat Island (UHI show that land cover change is the main factor of increasing Land Surface Temperature (LST in urban areas, especially conversion of vegetation and bare soil to concrete, asphalt and other man-made structures. On the other hand, other human activities like those which cause to burning fossil fuels, that increase the amount of carbon dioxide, may raise temperature in global scale in comparison with small scales (urban areas. In this study, multiple satellite images with different spatial and temporal resolutions have been used to determine Land Surface Temperature (LST variability in Tehran metropolitan area. High temporal resolution of AVHRR images have been used as the main data source when investigating temperature variability in the urban area. The analysis shows that UHI appears more significant at afternoon and night hours. But the urban class temperature is almost equal to its surrounding vegetation and bare soil classes at around noon. It also reveals that there is no specific difference in UHI intense during the days throughout the year. However, it can be concluded that in the process of city expansion in years, UHI has been grown both spatially and in magnitude. In order to locate land-cover types and relate them to LST, Thematic Mapper (TM images have been exploited. The influence of elevation on the LST has also been studied, using digital elevation model derived from SRTM database.

  10. ARTI refrigerant database

    Energy Technology Data Exchange (ETDEWEB)

    Calm, J.M. [Calm (James M.), Great Falls, VA (United States)

    1996-04-15

    The Refrigerant Database is an information system on alternative refrigerants, associated lubricants, and their use in air conditioning and refrigeration. It consolidates and facilitates access to property, compatibility, environmental, safety, application and other information. It provides corresponding information on older refrigerants, to assist manufacturers and those using alternative refrigerants, to make comparisons and determine differences. The underlying purpose is to accelerate phase out of chemical compounds of environmental concern. The database provides bibliographic citations and abstracts for publications that may be useful in research and design of air-conditioning and refrigeration equipment. The complete documents are not included, though some may be added at a later date. The database identifies sources of specific information on refrigerants. It addresses lubricants including alkylbenzene, polyalkylene glycol, polyolester, and other synthetics as well as mineral oils. It also references documents addressing compatibility of refrigerants and lubricants with metals, plastics, elastomers, motor insulation, and other materials used in refrigerant circuits. Incomplete citations or abstracts are provided for some documents. They are included to accelerate availability of the information and will be completed or replaced in future updates. Citations in this report are divided into the following topics: thermophysical properties; materials compatibility; lubricants and tribology; application data; safety; test and analysis methods; impacts; regulatory actions; substitute refrigerants; identification; absorption and adsorption; research programs; and miscellaneous documents. Information is also presented on ordering instructions for the computerized version.

  11. CO2 as a refrigerant

    CERN Document Server

    2014-01-01

    A first edition, the IIR guide “CO2 as a Refrigerant” highlights the application of carbon dioxide in supermarkets, industrial freezers, refrigerated transport, and cold stores as well as ice rinks, chillers, air conditioning systems, data centers and heat pumps. This guide is for design and development engineers needing instruction and inspiration as well as non-technical experts seeking background information on a specific topic. Written by Dr A.B. Pearson, a well-known expert in the field who has considerable experience in the use of CO2 as a refrigerant. Main topics: Thermophysical properties of CO2 – Exposure to CO2, safety precautions – CO2 Plant Design – CO2 applications – Future prospects – Standards and regulations – Bibliography.

  12. Condensation of refrigerants in horizontal microfin tubes. Numerical analysis of heat transfer for annular flow regime; Reibai no microfin tsuki suihei kannai gyoshuku. Kanjoryu ryoiki ni okeru netsudentatsu no suchi kaiseki

    Energy Technology Data Exchange (ETDEWEB)

    Nozu, S [Okayama Prefectural University, Okayama (Japan); Honda, H [Kyushu University, Fukuoka (Japan). Institute of Advanced Material Study

    1998-07-25

    A method for predicting the local heat transfer coefficient is presented for film condensation of vapor in a spirally grooved horizontal microfin-tube. Based on the flow observation study performed by the present authors, film flow model between fins in the annular flow regime is proposed. For the fin surface, laminar condensate film controlled by the combined effects of vapor shear and surface tension forces is analyzed. While, in the groove, thick condensate film driven by the vapor shear force is taken into consideration. A parameter which accounts for the transition from annular- to stratified flow regimes is also derived. The present and previous local heat transfer data for fluorocarbon refrigerants in the annular flow regime are found by the present numerical analysis to have a mean absolute deviation of 15.1 percent. 12 refs., 10 figs., 2 tabs.

  13. Developments in magnetocaloric refrigeration

    International Nuclear Information System (INIS)

    Brueck, Ekkes

    2005-01-01

    Modern society relies on readily available refrigeration. Magnetic refrigeration has three prominent advantages compared with compressor-based refrigeration. First, there are no harmful gases involved; second, it may be built more compactly as the working material is a solid; and third, magnetic refrigerators generate much less noise. Recently a new class of magnetic refrigerant-materials for room-temperature applications was discovered. These new materials have important advantages over existing magnetic coolants: they exhibit a large magnetocaloric effect (MCE) in conjunction with a magnetic phase-transition of first order. This MCE is larger than that of Gd metal, which is used in the demonstration refrigerators built to explore the potential of this evolving technology. In the present review we compare the different materials considering both scientific aspects and industrial applicability. Because fundamental aspects of MCE are not so widely discussed, we also give some theoretical considerations. (topical review)

  14. High-efficiency absorption-type heat pumps and refrigerators. From topology to the pilot plant; Hocheffiziente Absorptionsmaschinen zur Versorgung mit Kaelte und Waerme. Von der Topologie zur Pilotanlage

    Energy Technology Data Exchange (ETDEWEB)

    Ziegler, F.; Demmel, S.; Lamp, P. [Bayerisches Zentrum fuer Angewandte Energieforschung e.V. (ZAE Bayern), Wuerzburg (Germany); Kahn, R. [Technische Univ. Muenchen (Germany). Physik Dept. E19; Alefeld, G.

    1998-12-31

    Absorption-type heat pumps or refrigerators are systems operated with heat. They have been known for a long time and are frequently used especially in airconditioning in the USA and south-east Asia. However, the conventional technique used is subject to many physical limitations, restricting their broader use. The paper demonstrates ways of overcoming these restrictions, for instance by multi-stage design. The exploitation of topological principles much facilitates the synthesis of novel circuits. The technical relevance of such developments is demonstrated by means of selected examples of executed laboratory and pilot plants. Modern absorption technology saves resources and prevents environmental pollution by consuming less fossil energy compared with the conventional technique, for instance by harnessing the thermal potential of solar energy or utilizing waste heat and residual heat, and, not least, thanks to the use of natural refrigerants. (orig.) [Deutsch] Absorptionswaermepumpen oder -kaeltemaschinen sind durch Waerme angetriebene Anlagen, die seit langem bekannt sind und besonders in der Klimatechnik in den USA und im suedostasiatischen Raum haeufig eingesetzt werden. Die dabei verwendete konventionelle Technik unterliegt allerdings vielfaeltigen physikalischen Einschraenkungen, die ihre noch breitere Anwendung verhindern. Es wird gezeigt, wie diese Einschraenkungen beispielsweise durch Mehrstufigkeit ueberwunden werden koennen. Durch die Verwendung topologischer Grundsaetze wird die Synthese neuartiger Kreislaeufe stark vereinfacht. Die technische Bedeutung solcher Entwicklungen wird an ausgewaehlten Beispielen ausgefuehrter Labor- und Pilotanlagen gezeigt. Durch den im Vergleich zu konventioneller Technik geringeren Verbrauch an fossiler Energie, beispielsweise durch die thermische Nutzung von Sonnenenergie oder durch die Nutzung von Ab- oder Restwaerme und nicht zuletzt durch die Verwendung natuerlicher Kaeltemittel werden bei Einsatz moderner

  15. Contribution to magnetic refrigeration study at liquid helium study

    International Nuclear Information System (INIS)

    Lacaze, A.

    1985-10-01

    An experimental prototype of magnetic refrigerator operates, following a Carnot cycle, with gallium gadolinium garnet, from liquid helium at 4.2 0 K. Analysis of the cyle and heat exchanges allowed to improve performance up to get more than 50% of Carnot yield at 1.8 0 K and nearly 80% at 2.1 0 K. Operation conditions of a regenerator refrigerator between 4 and 20 0 K are studied. The association of a magnetic refrigerator and a gas refrigerator is analyzed. Among different ways to realize the magnetic stage, an active regenerator cycle is chosen. An experimental device is described [fr

  16. Analysis of a combined Rankine-vapour-compression refrigeration cycle

    International Nuclear Information System (INIS)

    Aphornratana, Satha; Sriveerakul, Thanarath

    2010-01-01

    This paper describes a theoretical analysis of a heat-powered refrigeration cycle, a combined Rankine-vapour-compression refrigeration cycle. This refrigeration cycle combines an Organic Rankine Cycle and a vapour-compression cycle. The cycle can be powered by low grade thermal energy as low as 60 deg. C and can produce cooling temperature as low as -10 deg. C. In the analysis, two combined Rankine-vapour-compression refrigeration cycles were investigated: the system with R22 and the system with R134a. Calculated COP values between 0.1 and 0.6 of both the systems were found.

  17. Refrigeration and global warming

    International Nuclear Information System (INIS)

    Anon.

    1997-01-01

    Some aspects of global warming in general, and the implications for refrigerants and refrigerator efficiency in particular, are briefly considered in a question and answer format. The concepts of Global Warming Potential (GWP) and Total Equivalent Warming Impact (TEWI) are explained. GWP is an index which allows a simple comparison to be make between the warming effects of different gases on a kg to kg basis relative to carbon. The GWP depends both on the lifetime of a substance in the atmosphere and its infra-red absorption capacity. The overall warming effect of operating a refrigeration system for its entire life is measured by its TEWI. Chloroflourocarbons (CFCs) which have been widely used as refrigerants are powerful greenhouse gases with high GWPs. Because of the bank of CFCs in refrigerating systems, their levels in the atmosphere are still increasing and it will be some time before refrigerant changes will be effective in reducing the warming effects of refrigerant releases. Hydrocarbons, hydroflourocarbons and ammonia all have a part to play as substitute refrigerants. Refrigerator efficiency is very important in terms of reducing CO 2 emissions. (UK)

  18. ARTI refrigerant database

    Energy Technology Data Exchange (ETDEWEB)

    Calm, J.M. [Calm (James M.), Great Falls, VA (United States)

    1998-08-01

    The Refrigerant Database is an information system on alternative refrigerants, associated lubricants, and their use in air conditioning and refrigeration. It consolidates and facilitates access to property, compatibility, environmental, safety, application and other information. It provides corresponding information on older refrigerants, to assist manufactures and those using alternative refrigerants, to make comparisons and determine differences. The underlying purpose is to accelerate phase out of chemical compounds of environmental concern. The database provides bibliographic citations and abstracts for publications that may be useful in research and design of air-conditioning and refrigeration equipment. The complete documents are not included, though some may be added at a later date. The database identifies sources of specific information on many refrigerants including propane, ammonia, water, carbon dioxide, propylene, ethers, and others as well as azeotropic and zeotropic blends of these fluids. It addresses lubricants including alkylbenzene, polyalkylene glycol, polyolester, and other synthetics as well as mineral oils. It also references documents addressing compatibility of refrigerants and lubricants with metals, plastics, elastomers, motor insulation, and other materials used in refrigerant circuits. Incomplete citations or abstracts are provided for some documents. They are included to accelerate availability of the information and will be completed or replaced in future updates.

  19. ARTI refrigerant database

    Energy Technology Data Exchange (ETDEWEB)

    Calm, J.M.

    1997-02-01

    The Refrigerant Database is an information system on alternative refrigerants, associated lubricants, and their use in air conditioning and refrigeration. It consolidates and facilitates access to property, compatibility, environmental, safety, application and other information. It provides corresponding information on older refrigerants, to assist manufacturers and those using alterative refrigerants, to make comparisons and determine differences. The underlying purpose is to accelerate phase out of chemical compounds of environmental concern. The database provides bibliographic citations and abstracts for publications that may be useful in research and design of air-conditioning and refrigeration equipment. The complete documents are not included, though some may be added at a later date. The database identifies sources of specific information on various refrigerants. It addresses lubricants including alkylbenzene, polyalkylene glycol, polyolester, and other synthetics as well as mineral oils. It also references documents addressing compatibility of refrigerants and lubricants with metals, plastics, elastomers, motor insulation, and other materials used in refrigerant circuits. Incomplete citations or abstracts are provided for some documents. They are included to accelerate availability of the information and will be completed or replaced in future updates.

  20. Improvement of a thermoelectric and vapour compression hybrid refrigerator

    International Nuclear Information System (INIS)

    Astrain, D.; Martínez, A.; Rodríguez, A.

    2012-01-01

    This paper presents the improvement in the performance of a domestic hybrid refrigerator that combines vapour compression technology for the cooler and freezer compartments, and thermoelectric technology for a new compartment. The heat emitted by the Peltier modules is discharged into the freezer compartment, forming a cascade refrigeration system. This configuration leads to a significant improvement in the coefficient of operation. Thus, the electric power consumption of the modules and the refrigerator decreases by 95% and 20% respectively, with respect to those attained with a cascade refrigeration system connected with the cooler compartment. The optimization process is based on a computational model that simulates the behaviour of the whole refrigerator. Two prototypes have been built and tested. Experimental results indicate that the temperature of the new compartment is easily set up at any value between 0 and −4 °C, the oscillation of this temperature is always lower than 0.4 °C, and the electric power consumption is low enough to include this hybrid refrigerator into energy efficiency class A, according European rules and regulations. - Highlights: ► Optimization of a vapour compression and thermoelectric hybrid refrigerator. ► Two prototypes built and tested. Computational model for the whole refrigerator. ► Electric power consumption of the modules and the refrigerator 95% and 20% lower. ► New compartment refrigerated with thermoelectric technology. ► Inner temperature adjustable from 0 to −4 °C. Oscillations lower than ±0.2 °C.

  1. Analysis of cooldown performance for Isabelle helium refrigerator

    International Nuclear Information System (INIS)

    Wu, K.C.; Brown, D.P.; Moore, R.W.

    1982-01-01

    The cooldown performance for the ISABELLE Helium refrigerator is analyzed in terms of the relationship between refrigerator and its load. The flow diagram for ISABELLE with its redundant turbines and heat exchangers is given. Cycle description and procedure for cooldown is described with the relationship between a refrigerator and its load illustrated. Pressure vs. temperature for ISABELLE load and the efficiency for a turbine are illustrated. The procedure for modeling the refrigerator and the concepts of maximizing the cooldown capacity are described. The results and discussion are accompanied with T-S diagrams for initial stage of cooldown and refrigerator characteristic at various return temperatures. The ISABELLE refrigerator with its reduncant expanders properly used achieves cooldown capacity well beyond its steady-state capacity. The cooldown rate at this stage relies on the design safety margin, which for the ISABELLE is 50%

  2. Next Generation Refrigeration Lubricants for Low Global Warming Potential/Low Ozone Depleting Refrigeration and Air Conditioning Systems

    Energy Technology Data Exchange (ETDEWEB)

    Hessell, Edward

    2013-12-31

    The goal of this project is to develop and test new synthetic lubricants that possess high compatibility with new low ozone depleting (LOD) and low global warming potential (LGWP) refrigerants and offer improved lubricity and wear protection over current lubricant technologies. The improved compatibility of the lubricants with the refrigerants, along with improved lubricating properties, will resulted in lower energy consumption and longer service life of the refrigeration systems used in residential, commercial and industrial heating, ventilating and air-conditioning (HVAC) and refrigeration equipment.

  3. Satellite combined heat and power plants and their legal autonomy; Satelliten-BHKW und deren rechtliche Eigenstaendigkeit

    Energy Technology Data Exchange (ETDEWEB)

    Loibl, Helmut [Kanzlei Paluka Sobola Loibl und Partner, Regensburg (Germany). Abt. Erneuerbare Energien

    2014-04-15

    Since the landmark decision by the German Court of Justice concerning the term ''plant'' in the context of biogas plants it should be clear beyond doubt that satellite combined heat and power plants (CHPs) are legally autonomous plants pursuant to Para. 3 No. 1 of the Renewable Energy Law (EEG). What has yet to be finally resolved are the conditions under which satellite CHPs are to be regarded as autonomous. This will be a question of distance on the one hand and of operation autonomy on the other. In the individual case both these factors will have to be assessed from the perspective of an average objective, informed citizen. To the extent that its heat and electricity are being utilised in a meaningful manner, the plant's autonomy will be beyond doubt, at least in operational terms. Regarding the remuneration to be paid for satellite CHPs the only case requiring special consideration is when a CHP falls under the EEG of 2012. In this case Para. 1 Section 1 Sentence 2 EEG provides that the remuneration for the CHP in question is to be calculated as if there was a single overall plant. To the extent that none of the CHPs fall under the EEG of 2012, the ruling remains that there is a separate entitlement to remuneration for each satellite CHP. This also holds in cases where satellite CHPs that were commissioned after 1 January 2012 are relocated. When a satellite CHP is replaced by a new one, the rate and duration of remuneration remain unchanged. However, when a new satellite CHP is added to an existing satellite CHP via a gas collector line it is to be treated according to the decisions of the Federal Court of Justice concerning biogas plant extensions: It falls under the law that applies to the existing CHP and has an entitlement to a new minimum remuneration period, albeit subject to the degression rate provided by the EEG version in question.

  4. Current fluctuations in quantum absorption refrigerators

    Science.gov (United States)

    Segal, Dvira

    2018-05-01

    Absorption refrigerators transfer thermal energy from a cold bath to a hot bath without input power by utilizing heat from an additional "work" reservoir. Particularly interesting is a three-level design for a quantum absorption refrigerator, which can be optimized to reach the maximal (Carnot) cooling efficiency. Previous studies of three-level chillers focused on the behavior of the averaged cooling current. Here, we go beyond that and study the full counting statistics of heat exchange in a three-level chiller model. We explain how to obtain the complete cumulant generating function of the refrigerator in a steady state, then derive a partial cumulant generating function, which yields closed-form expressions for both the averaged cooling current and its noise. Our analytical results and simulations are beneficial for the design of nanoscale engines and cooling systems far from equilibrium, with their performance optimized according to different criteria, efficiency, power, fluctuations, and dissipation.

  5. Load leveling on industrial refrigeration systems

    Science.gov (United States)

    Bierenbaum, H. S.; Kraus, A. D.

    1982-01-01

    A computer model was constructed of a brewery with a 2000 horsepower compressor/refrigeration system. The various conservation and load management options were simulated using the validated model. The savings available for implementing the most promising options were verified by trials in the brewery. Result show that an optimized methodology for implementing load leveling and energy conservation consisted of: (1) adjusting (or tuning) refrigeration systems controller variables to minimize unnecessary compressor starts, (2) The primary refrigeration system operating parameters, compressor suction pressure, and discharge pressure are carefully controlled (modulated) to satisfy product quality constraints (as well as in-process material cooling rates and temperature levels) and energy evaluating the energy cost savings associated with reject heat recovery, and (4) a decision is made to implement the reject heat recovery system based on a cost/benefits analysis.

  6. Computer model of the refrigeration system of an ice rink

    Energy Technology Data Exchange (ETDEWEB)

    Teyssedou, G.; Zmeureanu, R. [Concordia Univ., Centre for Building Studies, Montreal, PQ (Canada). Dept. of Building, Civil and Environmental Engineering; Giguere, D. [Natural Resources Canada, Varennes, PQ (Canada). CANMET Energy Technology Centre

    2008-07-01

    This paper presented a refrigeration system model of an existing ice rink using a component approach. The chillers, the ice-concrete slab and the controller were the 3 main components used in the simulations which were performed using both open and closed loop systems. The simulated ice rink refrigeration system was based on measurements taken in an existing indoor ice rink located in Montreal, Quebec. Measurements of the refrigeration system included electricity demand; heat flux on the ice sheet; exterior air temperature; ice temperature; return brine temperature; brine temperature at the pump; brine temperature at both evaporator exits; and refrigerant temperature and pressure at the expansion and condenser valve exits. Simulation results and measurements were found to be in good agreement. A computer model of the refrigeration system was developed using the TRNSYS 16 program. The refrigeration system was composed of 2 chillers using refrigerant R-22. The impact of heat recovery from the condensers on the energy demand for sanitary water heating was also estimated. The potential reduction of equivalent carbon dioxide emissions was calculated using the total equivalent warming impact (TEWI) criterion in an effort to estimate the refrigeration impact on global warming. 12 refs., 4 tabs., 12 figs.

  7. Qualitative comparison of duplex Stirling and absorption refrigerators in domestic applications

    Energy Technology Data Exchange (ETDEWEB)

    Shao, H. [Global Cooling BV, Zutphen (Netherlands)

    2000-07-01

    A qualitative comparison has been carried out between the duplex Stirling and the absorption refrigerator for domestic applications. The duplex Stirling has many advantages over the absorption refrigerator on efficiency, modulation, suitability, operating costs, pollution reduction. Based on the state of the art of free-piston gas-bearing and linear-motor Stirling engines and coolers, it appears technically and economically feasible to develop the duplex Stirling to compete with the absorption refrigerator for heat-driven domestic refrigeration. (orig.)

  8. Cryogenic mixed refrigerant processes

    CERN Document Server

    Venkatarathnam, Gadhiraju

    2010-01-01

    Teaches the need for refrigerant mixtures, the type of mixtures that can be used for different refrigeration and liquefaction applications, the different processes that can be used and the methods to be adopted for choosing the components of a mixture and their concentration for different applications.

  9. Refrigerated Warehouse Demand Response Strategy Guide

    Energy Technology Data Exchange (ETDEWEB)

    Scott, Doug [VaCom Technologies, San Luis Obispo, CA (United States); Castillo, Rafael [VaCom Technologies, San Luis Obispo, CA (United States); Larson, Kyle [VaCom Technologies, San Luis Obispo, CA (United States); Dobbs, Brian [VaCom Technologies, San Luis Obispo, CA (United States); Olsen, Daniel [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2015-11-01

    This guide summarizes demand response measures that can be implemented in refrigerated warehouses. In an appendix, it also addresses related energy efficiency opportunities. Reducing overall grid demand during peak periods and energy consumption has benefits for facility operators, grid operators, utility companies, and society. State wide demand response potential for the refrigerated warehouse sector in California is estimated to be over 22.1 Megawatts. Two categories of demand response strategies are described in this guide: load shifting and load shedding. Load shifting can be accomplished via pre-cooling, capacity limiting, and battery charger load management. Load shedding can be achieved by lighting reduction, demand defrost and defrost termination, infiltration reduction, and shutting down miscellaneous equipment. Estimation of the costs and benefits of demand response participation yields simple payback periods of 2-4 years. To improve demand response performance, it’s suggested to install air curtains and another form of infiltration barrier, such as a rollup door, for the passageways. Further modifications to increase efficiency of the refrigeration unit are also analyzed. A larger condenser can maintain the minimum saturated condensing temperature (SCT) for more hours of the day. Lowering the SCT reduces the compressor lift, which results in an overall increase in refrigeration system capacity and energy efficiency. Another way of saving energy in refrigerated warehouses is eliminating the use of under-floor resistance heaters. A more energy efficient alternative to resistance heaters is to utilize the heat that is being rejected from the condenser through a heat exchanger. These energy efficiency measures improve efficiency either by reducing the required electric energy input for the refrigeration system, by helping to curtail the refrigeration load on the system, or by reducing both the load and required energy input.

  10. Refrigerants and environment

    Science.gov (United States)

    Tsvetkov, O. B.; Laptev, Yu A.

    2017-11-01

    The refrigeration and air-conditioning industries are important sectors of the economy and represents about 15 % of global electricity consumptions. The chlorofluorocarbons also called CFCs are a class of refrigerants containing the halogens chlorine and/or fluorine on a carbon skeleton. Because of their environmental impact the Montreal Protocol was negotiated in 1987 to limit the production of certain CFCs and hydrochlirofluorocarbons (HCFCs) in developed and developing countries. The halogenated refrigerants are depleting the ozone layer also major contribution to the greenhouse effect. To be acceptable as a refrigerant a fluid must satisfy a variety of thermodynamic criteria and should be environment friendly with zero Ozone Depletion Potential and low Global Warming Potential. The perspective of a future phase down of HFCs is considered in this report taking into account a strategy for the phase out of HCFCs and perspective of choosing of various refrigerant followed by safety issues.

  11. OPTIMAL SYSNTHESIS PROCESSES OF LOW-TEMPERATURE CONDENSATION ASSOCIATED OIL GAS PLANT REFRIGERATION SYSTEM

    Directory of Open Access Journals (Sweden)

    O. Ostapenko

    2015-10-01

    Full Text Available Design of modern high-efficient systems is a key priority for the Energy Sector of Ukraine. The cooling technological streams of gas and oil refineries, including air coolers, water cooling and refrigeration systems for specific refrigerants are the objectives of the present study. Improvement of the refrigeration unit with refrigerant separation into fractions is mandatory in order to increase cooling capacity, lowering the boiling point of coolant and increasing the coefficient of target hydrocarbons extraction from the associated gas flow. In this paper it is shown that cooling temperature plays significant role in low-temperature condensation process. Two operation modes for refrigeration unit were proposed: permanent, in which the concentration of the refrigerant mixture does not change and dynamic, in which the concentration of refrigerant mixtures depends on the ambient temperature. Based on the analysis of exergy losses the optimal concentration of refrigerant mixtures propane/ethane for both modes of operation of the refrigeration unit has been determined. On the basis of the conducted pinch-analysis the modification of refrigeration unit with refrigerant separation into fractions was developed. Additional recuperative heat exchangers for utilization heat were added to the scheme. Several important measures to increase the mass flow rate of refrigerant through the second section of the refrigeration centrifugal compressor from 22.5 to 25 kg/s without violating the agreed operational mode of the compressor sections were implemented.

  12. Downscaling Satellite Land Surface Temperatures in Urban Regions for Surface Energy Balance Study and Heat Index Development

    Science.gov (United States)

    Norouzi, H.; Bah, A.; Prakash, S.; Nouri, N.; Blake, R.

    2017-12-01

    A great percentage of the world's population reside in urban areas that are exposed to the threats of global and regional climate changes and associated extreme weather events. Among them, urban heat islands have significant health and economic impacts due to higher thermal gradients of impermeable surfaces in urban regions compared to their surrounding rural areas. Therefore, accurate characterization of the surface energy balance in urban regions are required to predict these extreme events. High spatial resolution Land surface temperature (LST) in the scale of street level in the cities can provide wealth of information to study surface energy balance and eventually providing a reliable heat index. In this study, we estimate high-resolution LST maps using combination of LandSat 8 and infrared based satellite products such as Moderate Resolution Imaging Spectroradiometer (MODIS) and newly launched Geostationary Operational Environmental Satellite-R Series (GOES-R). Landsat 8 provides higher spatial resolution (30 m) estimates of skin temperature every 16 days. However, MODIS and GOES-R have lower spatial resolution (1km and 4km respectively) with much higher temporal resolution. Several statistical downscaling methods were investigated to provide high spatiotemporal LST maps in urban regions. The results reveal that statistical methods such as Principal Component Analysis (PCA) can provide reliable estimations of LST downscaling with 2K accuracy. Other methods also were tried including aggregating (up-scaling) the high-resolution data to a coarse one to examine the limitations and to build the model. Additionally, we deployed flux towers over distinct materials such as concrete, asphalt, and rooftops in New York City to monitor the sensible and latent heat fluxes through eddy covariance method. To account for the incoming and outgoing radiation, a 4-component radiometer is used that can observe both incoming and outgoing longwave and shortwave radiation. This

  13. 77 FR 72763 - Energy Conservation Program: Certification of Commercial and Industrial HVAC, Refrigeration and...

    Science.gov (United States)

    2012-12-06

    ... Commercial and Industrial HVAC, Refrigeration and Water Heating Equipment AGENCY: Office of Energy Efficiency...; commercial heating, ventilating, air-conditioning (HVAC) equipment; and commercial water heating equipment... refrigeration equipment; commercial HVAC equipment; commercial WH equipment; and walk-in coolers and freezers...

  14. Numerical simulation of pulse-tube refrigerators

    NARCIS (Netherlands)

    Lyulina, I.A.; Mattheij, R.M.M.; Tijsseling, A.S.; Waele, de A.T.A.M.

    2004-01-01

    A new numerical model has been introduced to study steady oscillatory heat and mass transfer in the tube section of a pulse-tube refrigerator. Conservation equations describing compressible gas flow in the tube are solved numerically, using high resolution schemes. The equation of conservation of

  15. A Histological Analysis of Visceral Organs to Evaluate the Effect of Duration of Heating From Refrigeration to Core Body Temperature for Ballistics Investigations.

    Science.gov (United States)

    Humphrey, Caitlin; Kumaratilake, Jaliya

    2017-12-01

    Animal organs have been used in ballistics research to investigate the effects on human organs. Such organs are refrigerated until the investigation to minimize autolytic degradation and at times have been reheated to the human core body temperature to simulate the in situ environment. The aim of this investigation was to study the microstructural changes that may occur in fresh chilled visceral organs of the thorax and abdomen (ie, heart, lung, liver, and kidney) during the period of reheating to 37°C. Fifty-millimeter cubes of porcine heart, lung, liver, and kidney were taken rapidly after slaughter, chilled overnight, and the next morning were reheated to core body temperature (37°C). Histological changes occurring in the tissues during the reheating phase were investigated. The findings indicated that no cytoplasmic or nuclear changes occurred in any of the tissues during the period of reheating. Therefore, reheating of animal organs to the human core body temperature is not necessary, if the organs are refrigerated.

  16. Thermoeconomic optimization of subcooled and superheated vapor compression refrigeration cycle

    International Nuclear Information System (INIS)

    Selbas, Resat; Kizilkan, Onder; Sencan, Arzu

    2006-01-01

    An exergy-based thermoeconomic optimization application is applied to a subcooled and superheated vapor compression refrigeration system. The advantage of using the exergy method of thermoeconomic optimization is that various elements of the system-i.e., condenser, evaporator, subcooling and superheating heat exchangers-can be optimized on their own. The application consists of determining the optimum heat exchanger areas with the corresponding optimum subcooling and superheating temperatures. A cost function is specified for the optimum conditions. All calculations are made for three refrigerants: R22, R134a, and R407c. Thermodynamic properties of refrigerants are formulated using the Artificial Neural Network methodology

  17. A horizontal dilution refrigerator for polarized target

    International Nuclear Information System (INIS)

    Isagawa, S.; Ishimoto, S.; Masaike, A.; Morimoto, K.

    1978-01-01

    A horizontal dilution refrigerator was constructed with a view to the spin frozen target and the deuteron polarized target. High cooling power at high temperature such as 3.7 mW at 400 mK serves for overcoming a heat load of microwave to polarize the nuclear spins in the target material. The cooling power at 50 mK was 50 μW, which is sufficient to hold the high nuclear polarization for long time. The lowest temperature reached was 26 mK. The refrigerator has rather simple heat exchangers, a long stainless steel double tube heat exchanger and two coaxial type heat exchangers with sintered copper. The mixing chamber is made of polytetrafluoroethylene (TFE) and demountable so that the target material can be easily put into it. (Auth.)

  18. Condensation of pure and near-azeotropic refrigerants in microfin tubes: A new computational procedure

    Energy Technology Data Exchange (ETDEWEB)

    Cavallini, A; Del Col, D; Mancin, S; Rossetto, L [Dipartimento di Fisica Tecnica, University of Padova, Via Venezia 1, Padova 35131 (Italy)

    2009-01-15

    Microfin tubes are widely used in air cooled and water cooled heat exchangers for heat pump and refrigeration applications during condensation or evaporation of refrigerants. In order to design heat exchangers and to optimize heat transfer surfaces, accurate procedures for computing pressure drops and heat transfer coefficients are necessary. This paper presents a new simple model for the prediction of the heat transfer coefficient to be applied to condensation in horizontal microfin tubes of halogenated and natural refrigerants, pure fluids or nearly azeotropic mixtures. The updated model accounts for refrigerant physical properties, two-phase flow patterns in microfin tubes and geometrical characteristics of the tubes. It is validated against a data bank of 3115 experimental heat transfer coefficients measured in different independent laboratories all over the world including diverse inside tube geometries and different condensing refrigerants among which R22, R134a, R123, R410A and CO{sub 2}. (author)

  19. Modeling tectonic heat flow and source rock maturity in the Rub' Al-Khali Basin (Saudi Arabia), with the help of GOCE satellite gravity data

    NARCIS (Netherlands)

    Abdul Fattah, R.; Meekes, S.; Bouman, J.; Ebbing, J.; Haagmans, R.

    2014-01-01

    A 3D basin modeling study was carried out to reconstruct the regional heat flow and source rock maturity in the Rub'al-Khali basin. Gravity gradient data from the GOCE satellite were used to model deep structures, such as the Moho interface. Tectonic heat flow was modeled using the GOCE-based Moho

  20. Design of refrigeration system using refrigerant R134a for macro compartment

    Science.gov (United States)

    Rani, M. F. H.; Razlan, Z. M.; Shahriman, A. B.; Yong, C. K.; Harun, A.; Hashim, M. S. M.; Faizi, M. K.; Ibrahim, I.; Kamarrudin, N. S.; Saad, M. A. M.; Zunaidi, I.; Wan, W. K.; Desa, H.

    2017-10-01

    The main objective of this study is to analyse and design an optimum cooling system for macro compartment. Current product of the refrigerator is not specified for single function and not compact in size. Hence, a refrigeration system using refrigerant R134a is aimed to provide instant cooling in a macro compartment with sizing about 150 × 150 × 250 mm. The macro compartment is purposely designed to fit a bottle or drink can, which is then cooled to a desired drinking temperature of about 8°C within a period of 1 minute. The study is not only concerned with analysing of heat load of the macro compartment containing drink can, but also focused on determining suitable heat exchanger volume for both evaporator and condenser, calculating compressor displacement value and computing suitable resistance value of the expansion valve. Method of optimization is used to obtain the best solution of the problem. Mollier diagram is necessary in the process of developing the refrigeration system. Selection of blower is made properly to allow air circulation and to increase the flow rate for higher heat transfer rate. Property data are taken precisely from thermodynamic property tables. As the main four components, namely condenser, compressor, evaporator and expansion valve are fully developed, the refrigeration system is complete.

  1. Modelling refrigerant distribution in microchannel evaporators

    DEFF Research Database (Denmark)

    Brix, Wiebke; Kærn, Martin Ryhl; Elmegaard, Brian

    2009-01-01

    of the refrigerant distribution is carried out for two channels in parallel and for two different cases. In the first case maldistribution of the inlet quality into the channels is considered, and in the second case a non-uniform airflow on the secondary side is considered. In both cases the total mixed superheat...... out of the evaporator is kept constant. It is shown that the cooling capacity of the evaporator is reduced significantly, both in the case of unevenly distributed inlet quality and for the case of non-uniform airflow on the outside of the channels.......The effects of refrigerant maldistribution in parallel evaporator channels on the heat exchanger performance are investigated numerically. For this purpose a 1D steady state model of refrigerant R134a evaporating in a microchannel tube is built and validated against other evaporator models. A study...

  2. Designing a magnet for magnetic refrigeration

    DEFF Research Database (Denmark)

    Bjørk, Rasmus

    This thesis investigates the design and optimization of a permanent magnet assembly for use in a magnetic refrigeration device. The heart of magnetic refrigeration is the adiabatic temperature change in the magnetocaloric material which is caused by the magnetic field. In order to design an ideal...... magnet assembly the magnetocaloric materials and the refrigeration process itself and their properties and performance as a function of magnetic field are investigated. For the magnetocaloric materials it is the magnetization, specific heat capacity and adiabatic temperature that are investigated...... as a function of the magnetic field in order to learn the properties of the optimal magnet assembly. The performance of the AMR as a function of the synchronization and width of the magnetic field with respect to the AMR cycle, the ramp rate and maximum value of the magnetic field are investigated. Other...

  3. Basics of Low-temperature Refrigeration

    CERN Document Server

    Alekseev, A.

    2014-07-17

    This chapter gives an overview of the principles of low temperature refrigeration and the thermodynamics behind it. Basic cryogenic processes - Joule-Thomoson process, Brayton process as well as Claude process - are described and compared. A typical helium laboratory refrigerator based on Claude process is used as a typical example of a low-temperature refrigeration system. A description of the hardware components for helium liquefaction is an important part of this paper, because the design of the main hardware components (compressors, turbines, heat exchangers, pumps, adsorbers, etc.) provides the input for cost calculation, as well as enables to estimate the reliability of the plant and the maintenance expenses. All these numbers are necessary to calculate the economics of a low temperature application.

  4. Basics of Low-temperature Refrigeration

    Energy Technology Data Exchange (ETDEWEB)

    Alekseev, A [Linde AG, Munich (Germany)

    2014-07-01

    This chapter gives an overview of the principles of low temperature refrigeration and the thermodynamics behind it. Basic cryogenic processes - Joule-Thomoson process, Brayton process as well as Claude process - are described and compared. A typical helium laboratory refrigerator based on Claude process is used as a typical example of a low-temperature refrigeration system. A description of the hardware components for helium liquefaction is an important part of this paper, because the design of the main hardware components (compressors, turbines, heat exchangers, pumps, adsorbers, etc.) provides the input for cost calculation, as well as enables to estimate the reliability of the plant and the maintenance expenses. All these numbers are necessary to calculate the economics of a low temperature application.

  5. Data mining techniques for thermophysical properties of refrigerants

    International Nuclear Information System (INIS)

    Kuecueksille, Ecir Ugur; Selbas, Resat; Sencan, Arzu

    2009-01-01

    This study presents ten modeling techniques within data mining process for the prediction of thermophysical properties of refrigerants (R134a, R404a, R407c and R410a). These are linear regression (LR), multi layer perception (MLP), pace regression (PR), simple linear regression (SLR), sequential minimal optimization (SMO), KStar, additive regression (AR), M5 model tree, decision table (DT), M5'Rules models. Relations depending on temperature and pressure were carried out for the determination of thermophysical properties as the specific heat capacity, viscosity, heat conduction coefficient, density of the refrigerants. Obtained model results for every refrigerant were compared and the best model was investigated. Results indicate that use of derived formulations from these techniques will facilitate design and optimize of heat exchangers which is component of especially vapor compression refrigeration system

  6. Ecological optimization for an irreversible magnetic Ericsson refrigeration cycle

    International Nuclear Information System (INIS)

    Wang Hao; Wu Guo-Xing

    2013-01-01

    An irreversible Ericsson refrigeration cycle model is established, in which multi-irreversibilities such as finite-rate heat transfer, regenerative loss, heat leakage, and the efficiency of the regenerator are taken into account. Expressions for several important performance parameters, such as the cooling rate, coefficient of performance (COP), power input, exergy output rate, entropy generation rate, and ecological function are derived. The influences of the heat leakage and the time of the regenerative processes on the ecological performance of the refrigerator are analyzed. The optimal regions of the ecological function, cooling rate, and COP are determined and evaluated. Furthermore, some important parameter relations of the refrigerator are revealed and discussed in detail. The results obtained here have general significance and will be helpful in gaining a deep understanding of the magnetic Ericsson refrigeration cycle. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  7. Flow-synchronous field motion refrigeration

    Science.gov (United States)

    Hassen, Charles N.

    2017-08-22

    An improved method to manage the flow of heat in an active regenerator in a magnetocaloric or an electrocaloric heat-pump refrigeration system, in which heat exchange fluid moves synchronously with the motion of a magnetic or electric field. Only a portion of the length of the active regenerator bed is introduced to or removed from the field at one time, and the heat exchange fluid flows from the cold side toward the hot side while the magnetic or electric field moves along the active regenerator bed.

  8. Public Refrigerated Warehouses

    Data.gov (United States)

    Department of Homeland Security — The International Association of Refrigerated Warehouses (IARW) came into existence in 1891 when a number of conventional warehousemen took on the demands of storing...

  9. Energy conservation in refrigerating machines by combining of thermo-static expansion valve and interior heat transfer material; Energieeinsparung in Kaelteanlagen durch Kombination von thermostatischem Expansionsventil und innerem Waermeuebertrager

    Energy Technology Data Exchange (ETDEWEB)

    Tambovtsev, Alexander

    2007-12-15

    The invention of the refrigerating machine enables to generate cold energy in any needed amount and at any desired temperature. However, cold energy generation requires driving energy. The target of this dissertation is to reduce the energy consumption of refrigerating plants considerably by means of an intelligent combination of the thermo-static expansion valve and the interior heat transfer medium. This combination should not deteriorate the reliability nor incur additional costs. Until today the two known components thermo-static expansion valve and interior heat transfer medium are considered as incompatible, because the simple connection of both components leads to an unstable control behaviour. After a detailed analysis of the causes for this instability the hypothesis is made, a stable working area can be found by means of a deliberate ''deterioration'' of the internal heat transfer medium. This ''deterioration'' can be e.g. a bypass of a part of the high-pressure flow or a parallel flow arrangement of the flows in the heat transfer medium. This hypothesis was primarily proved by experiments, but also by simulation calculations. A test stand was set-up for this purpose, which was used to test various configurations and control strategies. A considerable reduction of the energy consumption compared to conventional arrangements was achieved. (orig.) [German] Die Erfindung der Kaeltemaschine macht es moeglich, dass heute zu beliebiger Zeit Kaelte in benoetigter Menge und gewuenschter Temperatur erzeugt werden kann. Aber fuer die Kaelteerzeugung braucht man Antriebsenergie. Das Ziel dieser Doktorarbeit besteht darin, mit einer intelligenten Kombination von thermostatischem Expansionsventil (TEV) und innerem Waermeuebertrager (IWUe) den Energieverbrauch von Kaelteanlagen deutlich zu verringern, ohne dass dies zu einer Verschlechterung der Zuverlaessigkeit oder wesentlichen Mehrkosten fuehrt. Bis heute gelten die beiden

  10. Refrigeration systems and applications

    CERN Document Server

    Dincer, Ibrahim

    2010-01-01

    Refrigeration Systems and Applications, 2nd edition offers a comprehensive treatise that addresses real-life technical and operational problems, enabling the reader to gain an understanding of the fundamental principles and the practical applications of refrigeration technology. New and unique analysis techniques (including exergy as a potential tool), models, correlations, procedures and applications are covered, and recent developments in the field are included - many of which are taken from the author's own research activities in this area. The book also includes so

  11. PIPER Continuous Adiabatic Demagnetization Refrigerator

    Science.gov (United States)

    Kimball, Mark O.; Shirron, Peter J.; Canavan, Edgar R.; James, Bryan L.; Sampson, Michael A.; Letmate, Richard V.

    2017-01-01

    We report upon the development and testing of a 4-stage adiabatic demagnetization refrigerator (ADR) capable of continuous cooling at 0.100 Kelvin. This cooler is being built to cool the detector array aboard NASA's Primordial Inflation Polarization Explorer (PIPER) observatory. The goal of this balloon mission is to measure the primordial gravitational waves that should exist if the theory of cosmological inflation is correct. At altitude, the ADR will hold the array of transition-edge sensors at 100 mK continuously while periodically rejecting heat to a 1.2 K pumped helium bath. During testing on ground, the array is held at the same temperature but heat is rejected to a 4.2 K helium bath indicating the flexibility in this coolers design.

  12. Prediction of thermophysical properties of mixed refrigerants using artificial neural network

    International Nuclear Information System (INIS)

    Sencan, Arzu; Koese, Ismail Ilke; Selbas, Resat

    2011-01-01

    The determination of thermophysical properties of the refrigerants is very important for thermodynamic analysis of vapor compression refrigeration systems. In this paper, an artificial neural network (ANN) is proposed to determine properties as heat conduction coefficient, dynamic viscosity, kinematic viscosity, thermal diffusivity, density, specific heat capacity of refrigerants. Five alternative refrigerants are considered: R413A, R417A, R422A, R422D and R423A. The training and validation were performed with good accuracy. The thermophysical properties of the refrigerants are formulated using artificial neural network (ANN) methodology. Liquid and vapor thermophysical properties of refrigerants with new formulation obtained from ANN can be easily estimated. The method proposed offers more flexibility and therefore thermodynamic analysis of vapor compression refrigeration systems is fairly simplified.

  13. NLP modeling for the optimization of LiBr-H2O absorption refrigeration systems with exergy loss rate, heat transfer area, and cost as single objective functions

    DEFF Research Database (Denmark)

    Mussati, Sergio F.; Gernaey, Krist; Morosuk, Tatiana

    2016-01-01

    exergy loss rate, the total heat transfer area, and the total annual cost of the system. It was found that the optimal solution obtained by minimization of the total exergy loss rate provides “theoretical” upper bounds not only for the total heat transfer area of the system but also for each process unit...... and all stream temperatures, while the optimal solution obtained by minimization of the total heat transfer area provides the lower bounds for these model variables, to solve a cost optimization problem. The minimization of the total exergy loss rate by varying parametrically the available total heat...... transfer area between these bounds was also performed, allowing to see how the optimal distribution of the available total heat transfer area among the system components, as well as the operating conditions (stream temperature, pressure, composition, and mass flow rate) and heat loads, vary qualitatively...

  14. Statistics of Joule heating in the auroral zone and polar cap using Astrid-2 satellite Poynting flux

    Directory of Open Access Journals (Sweden)

    A. Olsson

    2004-12-01

    Full Text Available We make a statistical study of ionospheric Joule heating with the Poynting flux method using six months of Astrid-2/EMMA electric and magnetic field data during 1999 (solar maximum year. For the background magnetic field we use the IGRF model. Our results are in agreement with earlier statistical satellite studies using both the ΣPE2 method and the Poynting flux method. We present a rather comprehensive set of fitted Joule heating formulas expressing the Joule heating in given magnetic local time (MLT and invariant latitude (ILAT range under given solar illumination conditions as a function of the Kp index, the AE index, the Akasofu epsilon parameter and the solar wind kinetic energy flux. The study thus provides improved and more detailed estimates of the statistical Joule heating. Such estimates are necessary building blocks for future quantitative studies of the power budget in the magnetosphere and in the nightside auroral region. Key words. Ionosphere (electric fields and currents; ionosphere-magnetosphere interactions – Magnetospheric physics (magnetospheric configuration and dynamics

  15. Thermodynamic analysis of an absorption refrigeration system with ionic-liquid/refrigerant mixture as a working fluid

    International Nuclear Information System (INIS)

    Kim, Yoon Jo; Kim, Sarah; Joshi, Yogendra K.; Fedorov, Andrei G.; Kohl, Paul A.

    2012-01-01

    Thermodynamics of an ionic-liquid (IL) based absorption refrigeration system has been numerically analyzed. It provides an alternative to the normally toxic working fluids, such as the ammonia in conventional absorption systems. The use of ILs also eliminates crystallization and metal-compatibility problems of the water/LiBr system. Mixtures of refrigerants and imidazolium-based ILs are theoretically explored as the working fluid pairs in a miniature absorption refrigeration system, so as to utilize waste-heat to power a refrigeration/heat pump system for electronics cooling. A non-random two-liquid (NRTL) model was built and used to predict the solubility of the mixtures. Saturation temperatures at the evaporator and condenser were set at 25 °C and 50 °C, respectively, with the power dissipation of 100 W. Water in combination with [emim][BF 4 ] (1-ethyl-3-methylimidazolium tetrafluoroborate) gave the highest coefficient of performance (COP) around 0.9. The refrigerant/IL compatibility indicated by the circulation ratio, alkyl chain length of the IL, and thermodynamic properties of the refrigerants, such as latent heat of evaporation were proven to be important factors in determining the performance of the absorption system. The negative effect of high viscosity was mitigated by dilution of the IL with the refrigerant and the use of slightly larger microfluidic channel heat exchangers. -- Highlights: ► Mixtures of refrigerant/ionic-liquid are studied for absorption system. ► We carry out comprehensive theoretical thermodynamic analysis. ► The essential factors of refrigerant/IL affecting the performance are identified. ► Water/[emim][BF 4 ] showed the best performance of COP. ► The effects of high viscosity ILs on the system performance are not significant.

  16. Satellite data based approach for the estimation of anthropogenic heat flux over urban areas

    Science.gov (United States)

    Nitis, Theodoros; Tsegas, George; Moussiopoulos, Nicolas; Gounaridis, Dimitrios; Bliziotis, Dimitrios

    2017-09-01

    Anthropogenic effects in urban areas influence the thermal conditions in the environment and cause an increase of the atmospheric temperature. The cities are sources of heat and pollution, affecting the thermal structure of the atmosphere above them which results to the urban heat island effect. In order to analyze the urban heat island mechanism, it is important to estimate the anthropogenic heat flux which has a considerable impact on the urban energy budget. The anthropogenic heat flux is the result of man-made activities (i.e. traffic, industrial processes, heating/cooling) and thermal releases from the human body. Many studies have underlined the importance of the Anthropogenic Heat Flux to the calculation of the urban energy budget and subsequently, the estimation of mesoscale meteorological fields over urban areas. Therefore, spatially disaggregated anthropogenic heat flux data, at local and city scales, are of major importance for mesoscale meteorological models. The main objectives of the present work are to improve the quality of such data used as input for mesoscale meteorological models simulations and to enhance the application potential of GIS and remote sensing in the fields of climatology and meteorology. For this reason, the Urban Energy Budget concept is proposed as the foundation for an accurate determination of the anthropogenic heat discharge as a residual term in the surface energy balance. The methodology is applied to the cities of Athens and Paris using the Landsat ETM+ remote sensing data. The results will help to improve our knowledge on Anthropogenic Heat Flux, while the potential for further improvement of the methodology is also discussed.

  17. Dynamic design of gas sorption J-T refrigerator

    International Nuclear Information System (INIS)

    Chan, C.K.

    1986-01-01

    A long-life Joule-Thomson refrigerator which is heat powered, involves no sealing, and has few mechanical parts and is desirable for longterm sensor cooling in space. In the gas-sorption J-T refrigerator, cooling is achieved by gas sorption (either adsorption or absorption) processes. Currently, a modular, single-stage refrigerator is being designed and built to be operated at 20 K. The design was analyzed using a dynamic model, which is described here. The model includes the kinetics of the compressors and the heat switches, the heat transfer of the pre-coolers and the heat exchangers, the on/off ratio of the check valves, and the impedance of the J-T valve. The cooling power, the cycle time, and the operating conditions were obtained in terms of the power input, the heat sink temperature, and the J-T impedance

  18. Dynamic design of gas sorption J-T refrigerator

    Science.gov (United States)

    Chan, C. K.

    1986-01-01

    A long-life Joule-Thomson refrigerator which is heat powered, involves no sealing, and has few mechanical parts is desirable for long-term sensor cooling in space. In the gas-sorption J-T refrigerator, cooling is achieved by gas sorption (either adsorption or absorption) processes. Currently, a modular, single-stage refrigerator is being designed and built to be operated at 20 K. The design was analyzed using a dynamic model, which is described here. The model includes the kinetics of the compressors and the heat switches, the heat transfer of the pre-coolers and the heat exchangers, the on/off ratio of the check valves, and the impedance of the J-T valve. The cooling power, the cycle time, and the operating conditions were obtained in terms of the power input, the heat sink temperature, and the J-T impedance.

  19. Evaporation of new refrigerants on tubes with improved surfaces; Evaporation de nouveaux refrigerants sur des tubes a surface amelioree

    Energy Technology Data Exchange (ETDEWEB)

    Kattan, N.; Favrat, D.; Thome, J. R.; Nidegger, E.; Zuercher, O. [Ecole Polytechnique Federale, Lab. d` Energetique Industrielle (LENI), Lausanne (Switzerland)

    1995-07-15

    The substitution of old refrigerants in refrigeration systems, heat pumps and organic Rankine cycles for heat recovery, request a good knowledge of heat transfer properties of substitute fluids. The test measurements in LENI test facility (concentric tubes with water flowing in a counter-current flow) with new refrigerants like HFC134a, HCFC123, R-404A, R-402A, have established a new data bank with new refrigerants, a comparison with old refrigerants like CFC11, CFC12 CFC/HCFC502 and with existent correlations. Correlations were programmed to calculate and compare heat transfer coefficient during the tests. To develop a new correlation based on flow regimes, a high speed Sony video tape camera is used to observe and identify flow patterns. Important images are captured, digitalized, stored for later analysis and sent to a color plotter. Several flow pattern maps were programmed and compared to flow regimes observed on the test rig. Local flow boiling heat transfer coefficients were measured for HFC134a and HCFC123 evaporating inside a microfin tube. In addition, microfin heat transfer augmentation relative to plain tube test data was investigated. The presence of oil in the evaporator has an effect on heat transfer coefficient. Local flow boiling heat transfer coefficients were measured for refrigerant HFC134a-oil ester (Mobil EAL Arctic 68). A new thermodynamic approach for modeling mixtures of refrigerants and lubricating oils is developed. A very high accuracy, straight vibrating tube type of density flowmeter is used to measure oil concentrations of flowing HFC134a-oil mixtures. (author) 28 figs., 25 refs.

  20. Electron-beam-welded segmental heat pipes of AlMgSi 1 for the thermal model of the satellite Aeros-A

    Energy Technology Data Exchange (ETDEWEB)

    Hoell, H.; Lasar, H.

    1974-07-01

    For the purposes of tests with the thermal model of the German aeronomy satellite Aeros-A, a heat pipe system of optimized weight was developed in order to transport thermal energy from the solar cells of the cylindrical satellite to the conical bottom. Because of stringent requirements on the fabrication process, electron beam welding is used for bonding. The welding process is described and preliminary test results are given. (LEW)

  1. Estimating Summer Ocean Heating in the Arctic Ice Pack Using High-Resolution Satellite Imagery

    Science.gov (United States)

    2014-09-01

    8 D. THE BEAUFORT SEA ICE MARGINAL ICE ZONE ...............................9 1. Sea Ice - Albedo Feedback...seasonal evolution of sea ice albedo for MYI (blue) and FYI (red). Plot (c) is the daily solar heat input. Plot (d) is the time averaged solar heat... ice cover has decreased extensively, particularly in the summer months (from Lee et al. 2012). 13 1. Sea Ice - Albedo Feedback Albedo is a

  2. Carnot type magnetic refrigeration below 4.2 K - computer simulation

    International Nuclear Information System (INIS)

    Hashimoto, T.; Numazawa, T.; Maro, T.

    1984-01-01

    Cooling devices based on a utilization of the Carnot type magnetic refrigeration cycle are usually selected for the temperature range from 20 K to 1.8 K. However, the refrigeration power in the case of such devices is frequently limited by the heat transfer coefficient between the heat source and the magnetic working substance. Thus, in a magnetic refrigerator studied by Delpuech et al. (1981), the refrigeration power is mainly restricted by the heat transfer coefficient in the isothermal magnetization process at 4.2 K. The present investigation is concerned with the development of a method for achieving high refrigeration power on the basis of a study utilizing computer simulation. One of two methods considered for enhancing refrigeration power is related to the change in the magnetic field, while the other method involves an enlargement of the effective area of gadolinium-gallium-garnet (GGG) with the aid of deep grooves in the surface. 6 references

  3. ARTI Refrigerant Database

    Energy Technology Data Exchange (ETDEWEB)

    Cain, J.M. (Calm (James M.), Great Falls, VA (United States))

    1993-04-30

    The Refrigerant Database consolidates and facilitates access to information to assist industry in developing equipment using alternative refrigerants. The underlying purpose is to accelerate phase out of chemical compounds of environmental concern. The database provides bibliographic citations and abstracts for publications that may be useful in research and design of air-conditioning and refrigeration equipment. The complete documents are not included. The database identifies sources of specific information on R-32, R-123, R-124, R-125, R-134, R-134a, R-141b, R-142b, R-143a, R-152a, R-245ca, R-290 (propane), R-717 (ammonia), ethers, and others as well as azeotropic and zeotropic blends of these fluids. It addresses lubricants including alkylbenzene, polyalkylene glycol, ester, and other synthetics as well as mineral oils. It also references documents addressing compatibility of refrigerants and lubricants with metals, plastics, elastomers, motor insulation, and other materials used in refrigerant circuits. Incomplete citations or abstracts are provided for some documents to accelerate availability of the information and will be completed or replaced in future updates.

  4. Cryogenic forced convection refrigerating system

    International Nuclear Information System (INIS)

    Klee, D.J.

    1988-01-01

    This patent describes the method of refrigerating products by contact with a refrigerating gas which comprises introducing product into a refrigeration zone, contacting the product with the refrigerating gas for a sufficient time to refrigerate it to the appropriate extent and removing the refrigerated product. The improvement for producing the refrigeration gas from a liquid cryogen such that essentially all of the liquid cryogen is fully vaporized before contacting the product comprises: (a) introducing the liquid cryogen, selected from the group consisting of liquid air and liquid nitrogen, at elevated pressure into an ejector as the motive fluid to accelerate a portion of a warm refrigerating gas through the ejector while mixing the cryogen and gas to effect complete vaporization of the liquid cryogen and substantial cooling of the portion of the refrigerating gas resulting in a cold discharge gas which is above the liquefaction temperature of the cryogen; (b) introducing the cold discharge gas into a forced circulation pathway of refrigerating gas and producing a cold refrigerating gas which contacts and refrigerates product and is then at least partially recirculated; (c) sensing the temperature of the refrigerating gas in the forced circulation pathway and controlling the introduction of liquid cryogen with regard to the sensed temperature to maintain the temperature of the discharge gas above the liquefacton temperature of the cryogen utilized

  5. Helium refrigeration system for hydrogen liquefaction applications

    Science.gov (United States)

    Nair, J. Kumar, Sr.; Menon, RS; Goyal, M.; Ansari, NA; Chakravarty, A.; Joemon, V.

    2017-02-01

    Liquid hydrogen around 20 K is used as cold moderator for generating “cold neutron beam” in nuclear research reactors. A cryogenic helium refrigeration system is the core upon which such hydrogen liquefaction applications are built. A thermodynamic process based on reversed Brayton cycle with two stage expansion using high speed cryogenic turboexpanders (TEX) along with a pair of compact high effectiveness process heat exchangers (HX), is well suited for such applications. An existing helium refrigeration system, which had earlier demonstrated a refrigeration capacity of 470 W at around 20 K, is modified based on past operational experiences and newer application requirements. Modifications include addition of a new heat exchanger to simulate cryogenic process load and two other heat exchangers for controlling the temperatures of helium streams leading out to the application system. To incorporate these changes, cryogenic piping inside the cold box is suitably modified. This paper presents process simulation, sizing of new heat exchangers as well as fabrication aspects of the modified cryogenic process piping.

  6. Automatic control study of the icing research tunnel refrigeration system

    Science.gov (United States)

    Kieffer, Arthur W.; Soeder, Ronald H.

    1991-01-01

    The Icing Research Tunnel (IRT) at the NASA Lewis Research Center is a subsonic, closed-return atmospheric tunnel. The tunnel includes a heat exchanger and a refrigeration plant to achieve the desired air temperature and a spray system to generate the type of icing conditions that would be encountered by aircraft. At the present time, the tunnel air temperature is controlled by manual adjustment of freon refrigerant flow control valves. An upgrade of this facility calls for these control valves to be adjusted by an automatic controller. The digital computer simulation of the IRT refrigeration plant and the automatic controller that was used in the simulation are discussed.

  7. ARTI Refrigerant Database

    Energy Technology Data Exchange (ETDEWEB)

    Calm, J.M.

    1992-11-09

    The database provides bibliographic citations and abstracts for publications that may be useful in research and design of air- conditioning and refrigeration equipment. The database identifies sources of specific information on R-32, R-123, R-124, R-125, R-134, R-134a, R-141b, R-142b, R-143a, R-152a, R-245ca, R-290 (propane), R- 717 (ammonia), ethers, and others as well as azeotropic and zeotropic and zeotropic blends of these fluids. It addresses lubricants including alkylbenzene, polyalkylene glycol, ester, and other synthetics as well as mineral oils. It also references documents on compatibility of refrigerants and lubricants with metals, plastics, elastomers, motor insulation, and other materials used in refrigerant circuits. A computerized version is available that includes retrieval software.

  8. Carbon Dioxide-Lubricant Two-Phase Flow Patterns in Small Horizontal Wetted Wall Channels: The Effects of Refrigerant/Lubricant Thermophysical Properties

    Science.gov (United States)

    Seeton, Christopher John

    2009-01-01

    Microchannel heat exchangers are gaining popularity due to their ability to handle high pressures, reduce refrigerant charge, and reduce heat exchanger package size. These heat exchanger designs provide better heat exchange performance due to increased refrigerant side heat transfer coefficients and geometries that allow for a denser packing…

  9. High-voltage leak detection of a parenteral proteinaceous solution product packaged in form-fill-seal plastic laminate bags. Part 2. Method performance as a function of heat seal defects, product-package refrigeration, and package plastic laminate lot.

    Science.gov (United States)

    Rasmussen, Mats; Damgaard, Rasmus; Buus, Peter; Mulhall, Brian; Guazzo, Dana Morton

    2013-01-01

    Part 1 of this three-part research series detailed the development and validation of a high-voltage leak detection test (HVLD, also known as an electrical conductivity and capacitance test) for verifying the container-closure integrity of a small-volume laminate plastic bag containing an aqueous solution formulation of the rapid-acting insulin analogue, insulin aspart (NovoRapid®/NovoLog®) by Novo Nordisk A/S, Bagsværd, Denmark. Leak detection capability was verified using positive controls each with a single laser-drilled hole in the bag film face. In this Part 2, HVLD leak detection capability was further explored in four separate studies. Study 1 investigated the ability of HVLD to detect weaknesses and/or gaps in the bag heat seal. Study 2 checked the HVLD detection of bag holes in packages stored 4 days at ambient conditions followed by 17 days at refrigeration. Study 3 examined HVLD test results for packages tested when cold. Study 4 compared HVLD test results as a function of bag plastic film lots. The final Part 3 of this series will report the impact of HVLD exposure on product visual appearance and chemical stability. In Part 1 of this three-part series, a leak test method based on electrical conductivity and capacitance, also called high-voltage leak detection (HVLD), was used to find leaks in small plastic bags filled with a solution for injection of the rapid-acting insulin analogue, insulin aspart (NovoRapid®/NovoLog®) by Novo Nordisk A/S, Bagsværd, Denmark. In this Part 2, HVLD leak detection capability was further explored in four separate studies. Study 1 investigated the ability of HVLD to detect bag heat seal leaks. Study 2 checked HVLD's ability to detect bag holes after a total of 21 days at ambient plus refrigerated temperatures. Study 3 looked to see if HVLD results changed for packages tested when still cold. Study 4 compared HVLD results for multiple bag plastic film lots. The final Part 3 of this series will report any evidence of

  10. PERFORMANCE ANALYSIS OF VCR SYSTEM WITH VARYING THE DIAMETERS OF HELICAL CONDENSER COIL BY USING R-134A REFRIGERANT

    OpenAIRE

    R.Hussain Vali; P.Yagnasri; S.Naresh Kumar Reddy

    2016-01-01

    Vapor compression machine is a refrigerator in which the heat removed from the cold by evaporation of the refrigerant is given a thermal potential so that it can gravitate to a natural sink by compressing the vapor produced. Majority of the refrigerators works on the Vapor compression refrigeration system. The system consists of components like compressor, condenser, expansion valve and evaporator. The performance of the system depends on the performance of all the components of the system. ...

  11. Refrigeration Playbook: Natural Refrigerants; Selecting and Designing Energy-Efficient Commercial Refrigeration Systems That Use Low Global Warming Potential Refrigerants

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, Caleb [CTA Architects Engineers, Boise, ID (United States); Reis, Chuck [CTA Architects Engineers, Boise, ID (United States); Nelson, Eric [CTA Architects Engineers, Boise, ID (United States); Armer, James [CTA Architects Engineers, Boise, ID (United States); Arthur, Rob [CTA Architects Engineers, Boise, ID (United States); Heath, Richard [CTA Architects Engineers, Boise, ID (United States); Rono, James [CTA Architects Engineers, Boise, ID (United States); Hirsch, Adam [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Doebber, Ian [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2015-03-01

    This report provides guidance for selecting and designing energy efficient commercial refrigeration systems using low global warming potential refrigerants. Refrigeration systems are generally the largest energy end use in a supermarket type building, often accounting for more than half of a building's energy consumption.

  12. Upper ocean heat budget of western-north Pacific using satellite and ship observations

    Digital Repository Service at National Institute of Oceanography (India)

    Pankajakshan, T.; Sugimori, Y.; Akiyama, M.

    Surface layer (0-17~'C isotherm depth) heat balance of a closed rectangular system (the Kuroshio system) in the North-West Pacific has been examined for a period of 10 days (from 16th to 25th, October, 1991), by considering the residual of net...

  13. Efficiency analysis of alternative refrigerants for ejector cooling cycles

    International Nuclear Information System (INIS)

    Gil, Bartosz; Kasperski, Jacek

    2015-01-01

    Highlights: • Advantages of using alternative refrigerants as ejector refrigerants were presumed. • Computer software basing on theoretical model of Huang et al. (1999) was prepared. • Optimal temperature range of primary vapor for each working fluid was calculated. - Abstract: Computer software, basing on the theoretical model of Huang et al. with thermodynamic properties of selected refrigerants, was prepared. Investigation was focused on alternative refrigerants that belong to two groups of substances: common solvents (acetone, benzene, cyclopentane, cyclohexane and toluene) and non-flammable synthetic refrigerants applied in Organic Rankine Cycle (ORC) (R236ea, R236fa, R245ca, R245fa, R365mfc and RC318). Refrigerants were selected to detect a possibility to use them in ejector cooling system powered by a high-temperature heat source. A series of calculations were carried out for the generator temperature between 70 and 200 °C, with assumed temperatures of evaporation 10 °C and condensation 40 °C. Investigation revealed that there is no single refrigerant that ensures efficient operation of the system in the investigated temperature range of primary vapor. Each substance has its own maximum entrainment ratio and COP at its individual temperature of the optimum. The use of non-flammable synthetic refrigerants allows obtaining higher COP in the low primary vapor temperature range. R236fa was the most beneficial among the non-flammable synthetic refrigerants tested. The use of organic solvents can be justified only for high values of motive steam temperature. Among the solvents, the highest values of entrainment ratio and COP throughout the range of motive temperature were noted for cyclopentane. Toluene was found to be an unattractive refrigerant from the ejector cooling point of view

  14. Designing a magnet for magnetic refrigeration

    Energy Technology Data Exchange (ETDEWEB)

    Bjoerk, R

    2010-03-15

    This thesis investigates the design and optimization of a permanent magnet assembly for use in a magnetic refrigeration device. The heart of magnetic refrigeration is the adiabatic temperature change in the magnetocaloric material which is caused by the magnetic field. In order to design an ideal magnet assembly the magnetocaloric materials and the refrigeration process itself and their properties and performance as a function of magnetic field are investigated. For the magnetocaloric materials it is the magnetization, specific heat capacity and adiabatic temperature that are investigated as functions of the magnetic field. Following this the process utilized by a magnetic refrigerator to provide cooling is investigated using a publicly available one dimensional numerical model. This process is called active magnetic regeneration (AMR). The aim is to determine the performance of the AMR as a function of the magnetic field in order to learn the properties of the optimal magnet assembly. The performance of the AMR as a function of the synchronization and width of the magnetic field with respect to the AMR cycle, the ramp rate and maximum value of the magnetic field are investigated. Other published magnet designs used in magnetic refrigeration devices are also evaluated, using a figure of merit based on the properties of the investigated magnetocaloric materials, to learn the properties of the best magnet designs to date. Following this investigation the Halbach cylinder, which is a hollow permanent magnet cylinder with a rotating remanent flux density, is investigated in detail as it forms the basis of many magnet designs used in magnetic refrigeration. Here the optimal dimensions of a Halbach cylinder, as well as analytical calculations of the magnetic field for a Halbach cylinder of infinite length, are presented. Once it has been determined which properties are desirable for a magnet used in magnetic refrigeration the design of a new magnet is described. This is

  15. Portable refrigerant charge meter and method for determining the actual refrigerant charge in HVAC systems

    Science.gov (United States)

    Gao, Zhiming; Abdelaziz, Omar; LaClair, Tim L.

    2017-08-08

    A refrigerant charge meter and a method for determining the actual refrigerant charge in HVAC systems are described. The meter includes means for determining an optimum refrigerant charge from system subcooling and system component parameters. The meter also includes means for determining the ratio of the actual refrigerant charge to the optimum refrigerant charge. Finally, the meter includes means for determining the actual refrigerant charge from the optimum refrigerant charge and the ratio of the actual refrigerant charge to the optimum refrigerant charge.

  16. Automotive exhaust gas flow control for an ammonia–water absorption refrigeration system

    International Nuclear Information System (INIS)

    Rêgo, A.T.; Hanriot, S.M.; Oliveira, A.F.; Brito, P.; Rêgo, T.F.U.

    2014-01-01

    A considerable part of the energy generated by an automotive internal combustion engine is wasted as heat in the exhaust system. This wasted heat could be recovered and applied to power auxiliary systems in a vehicle, contributing to its overall energy efficiency. In the present work, the experimental analysis of an absorption refrigeration system was performed. The exhaust system of an automotive internal combustion engine was connected to the generator element of an absorption refrigeration system. The performance of the absorption refrigerator was evaluated as a function of the supplied heat. The use of a control strategy for the engine exhaust gas mass flow rate was implemented to optimize the system. Exhaust gas flow was controlled by step-motor actuated valves commanded by a microcontroller in which a proportional-integral control scheme was implemented. Information such as engine torque, speed, key temperatures in the absorption cycle, as well as internal temperatures of the refrigerator was measured in a transient regime. The results indicated that the refrigeration system exhibited better performance when the amount of input heat is controlled based on the temperature of the absorption cycle generator. It was possible to conclude that, by dynamically controlling the amount of input heat, the utilisation range of the absorption refrigeration system powered by exhaust gas heat could be expanded in order to incorporate high engine speed operating conditions. - Highlights: •An absorption refrigerator was driven by automotive exhaust gas heat. •A system for controlling the refrigeration system heat input was developed. •Excessive exhaust gas heat leads to ineffective operation of the refrigerator. •Control of refrigerator's generator temperature led to better performance. •The use of exhaust gas was possible for high engine speeds

  17. 2016 German refrigeration and air conditioning meeting. Proceedings

    International Nuclear Information System (INIS)

    2016-01-01

    The following topics were dealt with: Large cryogenic facilities, relief valves, liquid helium, liquid-nitrogen and liquid hydrogen cooling, new concepts, foundations and materials of the heat-pump techniques, evaporation, phase-change materials, absorption, afterheat usage, ionic liquids, sorption, condensers, heat exchangers, back-cooling systems, refrigerants, caron dioxide, mobile applications, efficiency and optimization, air conditioning.

  18. Helium refrigerator for 'SULTAN'

    International Nuclear Information System (INIS)

    Arpagaus, M.; Erlach, H.; Quack, H.

    1984-01-01

    The authors describe the helium refrigerator designed for the SULTAN test facility. SULTAN (Supraleiter-Testanlage) is intended to serve for the developments and testing of high field superconducting magnets. These magnets are needed mainly for future applications in nuclear fusion. (Auth.)

  19. Dimensioning of flanged heat exchangers using the CYRANO software: pure refrigerants and mixtures; Dimensionnement des batteries a ailettes a l`aide du logiciel CYRANO: frigorigenes purs et melanges

    Energy Technology Data Exchange (ETDEWEB)

    Bensafi, A; Borg, S [CETIAT, Centre Technique des Industries Aerauliques et Thermiques, 69 - Villeurbanne (France)

    1998-12-31

    A software for the dimensioning and simulation of flanged heat exchangers is presented. This software divides the exchanger into pipe sections in which local values of physical properties of fluids and thermal exchange coefficients are used, and for which individual thermal-hydraulic performances are determined. CYRANO can be used for condensers, evaporators and monophase exchanges, with refrigerants like water, R22, R134a and R32/R125/R134a mixtures. The software can be used also in the case of specified complex circuits, equipped with smooth or grooved pipes and with smooth continuous, corrugated or slatted flanges with non-homogeneous air temperature and velocity distributions. The validation of CYRANO was performed on 7 exchangers with and without humidity condensation on the flanges. Comparisons with test results show that the average of errors in exchanged powers is of about 5%, and of about 30% in the case of internal pressure drops. Some simulations of exchangers with HFC mixtures are also presented. (J.S.) 34 refs.

  20. Dimensioning of flanged heat exchangers using the CYRANO software: pure refrigerants and mixtures; Dimensionnement des batteries a ailettes a l`aide du logiciel CYRANO: frigorigenes purs et melanges

    Energy Technology Data Exchange (ETDEWEB)

    Bensafi, A.; Borg, S. [CETIAT, Centre Technique des Industries Aerauliques et Thermiques, 69 - Villeurbanne (France)

    1997-12-31

    A software for the dimensioning and simulation of flanged heat exchangers is presented. This software divides the exchanger into pipe sections in which local values of physical properties of fluids and thermal exchange coefficients are used, and for which individual thermal-hydraulic performances are determined. CYRANO can be used for condensers, evaporators and monophase exchanges, with refrigerants like water, R22, R134a and R32/R125/R134a mixtures. The software can be used also in the case of specified complex circuits, equipped with smooth or grooved pipes and with smooth continuous, corrugated or slatted flanges with non-homogeneous air temperature and velocity distributions. The validation of CYRANO was performed on 7 exchangers with and without humidity condensation on the flanges. Comparisons with test results show that the average of errors in exchanged powers is of about 5%, and of about 30% in the case of internal pressure drops. Some simulations of exchangers with HFC mixtures are also presented. (J.S.) 34 refs.

  1. Terminology for refrigerating machinery in 5 languages with definitions. CECOMAF terminology English, French, German, Italian and Spanish. Terminologie fuer kaeltetechnische Erzeugnisse in 5 Sprachen mit Definitionen. CECOMAF Terminologie English, Francais, Deutsch, Italiano, Espanol

    Energy Technology Data Exchange (ETDEWEB)

    1986-01-01

    The dictionary covers the following topics: Directions for user, alphabetical list, subject index, main groups: Refrigerating systems and plants, compressors, heat exchangers and apparatus, control and safety devices, equipment for refrigerated storage and transport, refrigerators and refrigerated cabinets, special cooling and freezing equipment, miscellaneous; definitions for the above mentioned main groups, and corrections.

  2. Change of the high-latitude ionosphere during heating by a powerful short radio wave of the EISCAT/Heating complex according to signals of the GLONASS satellite and the incoherent scattering radar

    Directory of Open Access Journals (Sweden)

    Tereshchenko E. D.

    2018-03-01

    Full Text Available Results of observations of variations of temperature, electron concentration and total electron content of the high-latitude region of the ionosphere during its modification by powerful short radio waves of the heating complex EISCAT/Heating (Tromsø, Norway according to signals of the GLONASS satellites and the incoherent scattering UHF EISCAT radar (Tromsø, Norway have been provided. The geometry of passes of the GLONASS and GPS satellites for operating conditions of the heating complex in Tromsø has been considered. It has been shown that during the experiments on the EISCAT/Heating complex for the study of the modified structure of the high-latitude ionosphere it is more convenient to use the GLONASS satellites. Parameters of orbits of these satellites allow researching changes of total electron content in the direction along the geomagnetic field line at the place of observation. It has been shown that during heating of the ionosphere by powerful short radio waves its structure is becoming an irregular one. Operation of the heating complex in the mode "switched on – switched off" has caused appearance of wavy variations of total electron content with the periods close to the heating period. The main features of behavior of the total electron content in the case of the continuous heating of the ionosphere in the direction of the magnetic zenith according to the GLONASS satellite are: reduction of total electron content in the central zone of the antenna diagram, i. e. in the direction of the magnetic zenith, and presence of the increased values of total electron content at the edges of the heating zone. According to the incoherent scattering radar the heating of the ionosphere by the powerful short radio wave has created the region of the increased electron temperature and electron concentration along the direction of the magnetic zenith. The behavior of total electron content according to the GLONASS satellite and the radar of

  3. 300 W - 1.75 K TORE SUPRA refrigerator cold centrifugal compressors report

    International Nuclear Information System (INIS)

    Gistau, G.M.; Pecoud, Y.; Ravex, A.E.

    1988-01-01

    The centrifugal helium compressors for the TORE SUPRA tokamak refrigerator were designed and manufactured by L'Air Liquide and tested at nominal conditions on a custom test rig. The refrigerator is now installed and all acceptance tests have been completed. Other tests were carried out off design conditions with the machines installed in the TORE SUPRA refrigerator. The results of these tests, including compression ratio, efficiency, and heat losses, are discussed

  4. Precipitation and Latent Heating Distributions from Satellite Passive Microwave Radiometry. Part II: Evaluation of Estimates Using Independent Data

    Science.gov (United States)

    Yang, Song; Olson, William S.; Wang, Jian-Jian; Bell, Thomas L.; Smith, Eric A.; Kummerow, Christian D.

    2006-01-01

    Rainfall rate estimates from spaceborne microwave radiometers are generally accepted as reliable by a majority of the atmospheric science community. One of the Tropical Rainfall Measuring Mission (TRMM) facility rain-rate algorithms is based upon passive microwave observations from the TRMM Microwave Imager (TMI). In Part I of this series, improvements of the TMI algorithm that are required to introduce latent heating as an additional algorithm product are described. Here, estimates of surface rain rate, convective proportion, and latent heating are evaluated using independent ground-based estimates and satellite products. Instantaneous, 0.5 deg. -resolution estimates of surface rain rate over ocean from the improved TMI algorithm are well correlated with independent radar estimates (r approx. 0.88 over the Tropics), but bias reduction is the most significant improvement over earlier algorithms. The bias reduction is attributed to the greater breadth of cloud-resolving model simulations that support the improved algorithm and the more consistent and specific convective/stratiform rain separation method utilized. The bias of monthly 2.5 -resolution estimates is similarly reduced, with comparable correlations to radar estimates. Although the amount of independent latent heating data is limited, TMI-estimated latent heating profiles compare favorably with instantaneous estimates based upon dual-Doppler radar observations, and time series of surface rain-rate and heating profiles are generally consistent with those derived from rawinsonde analyses. Still, some biases in profile shape are evident, and these may be resolved with (a) additional contextual information brought to the estimation problem and/or (b) physically consistent and representative databases supporting the algorithm. A model of the random error in instantaneous 0.5 deg. -resolution rain-rate estimates appears to be consistent with the levels of error determined from TMI comparisons with collocated

  5. Precipitation and Latent Heating Distributions from Satellite Passive Microwave Radiometry. Part 2; Evaluation of Estimates Using Independent Data

    Science.gov (United States)

    Yang, Song; Olson, William S.; Wang, Jian-Jian; Bell, Thomas L.; Smith, Eric A.; Kummerow, Christian D.

    2004-01-01

    Rainfall rate estimates from space-borne k&ents are generally accepted as reliable by a majority of the atmospheric science commu&y. One-of the Tropical Rainfall Measuring Mission (TRh4M) facility rain rate algorithms is based upon passive microwave observations fiom the TRMM Microwave Imager (TMI). Part I of this study describes improvements in the TMI algorithm that are required to introduce cloud latent heating and drying as additional algorithm products. Here, estimates of surface rain rate, convective proportion, and latent heating are evaluated using independent ground-based estimates and satellite products. Instantaneous, OP5resolution estimates of surface rain rate over ocean fiom the improved TMI algorithm are well correlated with independent radar estimates (r approx. 0.88 over the Tropics), but bias reduction is the most significant improvement over forerunning algorithms. The bias reduction is attributed to the greater breadth of cloud-resolving model simulations that support the improved algorithm, and the more consistent and specific convective/stratiform rain separation method utilized. The bias of monthly, 2.5 deg. -resolution estimates is similarly reduced, with comparable correlations to radar estimates. Although the amount of independent latent heating data are limited, TMI estimated latent heating profiles compare favorably with instantaneous estimates based upon dual-Doppler radar observations, and time series of surface rain rate and heating profiles are generally consistent with those derived from rawinsonde analyses. Still, some biases in profile shape are evident, and these may be resolved with: (a) additional contextual information brought to the estimation problem, and/or; (b) physically-consistent and representative databases supporting the algorithm. A model of the random error in instantaneous, 0.5 deg-resolution rain rate estimates appears to be consistent with the levels of error determined from TMI comparisons to collocated radar

  6. Assessment of urban heat Island for Craiova from satellite-based LST

    Science.gov (United States)

    Udristioiu, Mihaela Tinca; Velea, Liliana; Bojariu, Roxana; Sararu, Silviu Constantin

    2017-12-01

    The urban heat island is defined as an excess of heating in urban areas compared with surrounding rural zones which is illustrated by higher surface and air temperatures in the inner part of the cities. The aim of this study is to identify the UHI effect for Craiova - the largest city in the South-Western part of Romania - and to assess its intensity during summer. To this end, MODIS Land surface temperature (LST) for day and night for summer months (June, July, August), in the interval 2002-2017, as well as yearly Land Cover Type (LCT) data also from MODIS were employed. Furthermore, measurements of air and soil temperature from meteorological station Craiova, available from the National Meteorological Administration database, were used to investigate their relation with LST. The analysis shows that in the urban area of Craiova the long-term summer mean LST is about 4 °C (2 °C), higher than in the rural area during daytime (nighttime). During high temperatures episodes, the mean daytime LST reaches 45-47 °C in the city, while the difference from the rural surrounding area is of 2-3 °C. A high correlation (0.77-0.83) is found between LST and air temperature for all land-use types in the area considered. Both LST and 2m-air temperature time-series manifest an increasing linear tendency over the period considered, being more pronounced during the day.

  7. Theoretical research on the performance of the transcritical ejector refrigeration cycle with various refrigerants

    International Nuclear Information System (INIS)

    Wang, F.; Li, D.Y.; Zhou, Y.

    2015-01-01

    The transcritical ejector refrigeration cycle (TERC), which has shown an attractive alternative to the ejector refrigeration systems, can better match large variable-temperature heat sources and yields higher COP. In this paper, in order to find a proper working fluid for the TERC, the performance of the TERC with CO_2 and various working fluids with low critical temperatures including R1270, R32, R143a, R125 and R115 are studied and compared. A thermodynamic model for ejector is set up to simulate the ejector by introducing the real properties of refrigerants. The results indicate that R1270 has the highest COP at the same heat source condition and medium working pressures, and is one of environment-friendly working fluids, hence R1270 is the most proper one. The COP of the transcritical cycle is higher than that of the subcritical cycle, and The effective performance coefficient COP_m of the transcritical cycle is also better. When the heater outlet temperature is increased, its system COP_m improves, but its system COP almost does not change. - Highlights: • A thermodynamic model is used to simulate the ejector with real properties. • The performance of the TERC with various refrigerants is compared. • The environment-friendly working fluid of R1270 shows the most proper one. • The COP of the transcritical cycle is higher than that of the subcritical cycle.

  8. Advanced exergoeconomic analysis of the multistage mixed refrigerant systems

    International Nuclear Information System (INIS)

    Mehrpooya, Mehdi; Ansarinasab, Hojat

    2015-01-01

    Highlights: • Advanced exergoeconomic analysis is performed for mixed refrigerant systems. • Cost of investment is divided into avoidable/unavoidable and endogenous/exogenous. • Results show that interactions between the components is not considerable. - Abstract: Advanced exergoeconomic analysis is applied on three multi stage mixed refrigerant liquefaction processes. They are propane precooled mixed refrigerant, dual mixed refrigerant and mixed fluid cascade. Cost of investment and exergy destruction for the components with high inefficiencies are divided into avoidable/unavoidable and endogenous/exogenous parts. According to the avoidable exergy destruction cost in propane precooled mixed refrigerant process, C-2 compressor with 455.5 ($/h), in dual mixed refrigerant process, C-1 compressor with 510.8 ($/h) and in mixed fluid cascade process, C-2/1 compressor with 338.8 ($/h) should be considered first. A comparison between the conventional and advanced exergoeconomic analysis is done by three important parameters: Exergy efficiency, exergoeconomic factor and total costs. Results show that interactions between the process components are not considerable because cost of investment and exergy destruction in most of them are endogenous. Exergy destruction cost of the compressors is avoidable while heat exchangers and air coolers destruction cost are unavoidable. Investment cost of heat exchangers and air coolers are avoidable while compressor’s are unavoidable

  9. A comparison between two methods of generating power, heat and refrigeration via biomass based Solid Oxide Fuel Cell: A thermodynamic and environmental analysis

    International Nuclear Information System (INIS)

    Mortazaei, M.; Rahimi, M.

    2016-01-01

    Highlights: • Two novel trigeneration systems based biomass and Solid Oxide Fuel Cell are compared. • A complete environmental analysis for three different cases is conducted. • Digester based system has 14.56% more exergetic efficiency than gasifier based one. • Gasifier based system has 14.31% more energetic efficiency than Digester based one. • Gasifier, Digester and air heat exchanger have the highest exergy destruction. - Abstract: Utilization of biomass energy is of prevalence focus these days. Using these fuels to run the fuel cells is of primary interest. In this regard, two new trigeneration systems (producing power and heating alongside with cooling) based on solid oxide fuel cell fed by either the syngas or biogas are proposed. The performance of systems is analyzed and compared with each other from the thermodynamic viewpoint. Applying the conservation of mass and energy as well as the exergy for each system component and using the engineering equation solver, the system’s performance are modeled. Through a parametric study, the effects of some key variables such as the current density and the fuel utilization factor in the systems’ performance are investigated. In addition, considering the system as a combination of three subsystems, that is, the power generation system, heat and power generation system and trigeneration system, an environmental impact assessment in terms of Carbon dioxide emission is carried out for both digester based Solid Oxide Fuel Cell and gasifier based one. It is observed that using biogas from digester leads to more exergetic (which is 14.56%) and less energetic efficiency (Which is 14.31%), with a Carbon dioxide emission of 17.87 ton/MW h for the tri-generation system. The value of this parameter is 21.32 ton/MW h when gasifier is used as the supplier of fuel for solid oxide fuel cell.

  10. Non-linear and adaptive control of a refrigeration system

    DEFF Research Database (Denmark)

    Rasmussen, Henrik; Larsen, Lars F. S.

    2011-01-01

    are capable of adapting to variety of systems. This paper proposes a novel method for superheat and capacity control of refrigeration systems; namely by controlling the superheat by the compressor speed and capacity by the refrigerant flow. A new low order nonlinear model of the evaporator is developed......In a refrigeration process heat is absorbed in an evaporator by evaporating a flow of liquid refrigerant at low pressure and temperature. Controlling the evaporator inlet valve and the compressor in such a way that a high degree of liquid filling in the evaporator is obtained at all compressor...... capacities ensures a high energy efficiency. The level of liquid filling is indirectly measured by the superheat. Introduction of variable speed compressors and electronic expansion valves enables the use of more sophisticated control algorithms, giving a higher degree of performance and just as important...

  11. An overview of adsorptive processes in refrigeration systems

    Directory of Open Access Journals (Sweden)

    Wolak Eliza

    2016-01-01

    Full Text Available Economic reasons and quest for new solutions based on recovering the energy have provoked an increase of interest in the adsorption technology in the refrigeration industry. The confirmation can be the fact that number of published research is on rise. Adsorption appliances may turn out to be an alternative to compression-type coolers. They use ecological chemical agents instead of substances which are aggressive and harmful to the environment. For regeneration of adsorptive refrigeration systems one can use cheap energy in a form of: industrial waste heat, energy of solar radiation and cheap electric power. The paper presents principles of operation as well as advantages and disadvantages of adsorptive refrigeration systems. Basing on literature the most frequently used adsorbent – adsorbate systems – which are employed in refrigeration industry – have been characterized. A review of construction solutions of systems on both laboratory and industrial scale has been made.

  12. Helium refrigeration system for BNL colliding beam accelerator

    International Nuclear Information System (INIS)

    Brown, D.P.; Farah, Y.; Gibbs, R.J.; Schlafke, A.P.; Schneider, W.J.; Sondericker, J.H.; Wu, K.C.

    1983-01-01

    A Helium Refrigeration System which will supply the cooling required for the Colliding Beam Accelerator at Brookhaven National Laboratory is under construction. Testing of the compressor system is scheduled for late 1983 and will be followed by refrigerator acceptance tests in 1984. The refrigerator has a design capacity of 24.8 kW at a temperature level near 4K while simultaneously producing 55 kW for heat shield loads at 55K. When completed, the helium refrigerator will be the world's largest. Twenty-five oil-injected screw compressors with an installed total of 23,250 horsepower will supply the gas required. One of the unique features of the cycle is the application of three centrifugal compressors used at liquid helium temperature to produce the low temperatures (2.5K) and high flow rates (4154 g/s) required for this service

  13. World's first ejector cycle for mobile refrigerators to stop global warming

    Energy Technology Data Exchange (ETDEWEB)

    Takeuchi, Hirotsugu [Denso Corporation, Kariya (Japan); Gyoeroeg, Tibor [DENSO AUTOMOTIVE Deutschland GmbH, Eching (Germany)

    2010-07-01

    The development of energy-saving technologies is in great demand recently to stop global warming. We are committed to developing the Ejector Cycle as an energy-saving technology for refrigerators and air conditioners. The ejector, which is an energy-saving technological innovation, improves the efficiency of the refrigeration cycle by effectively using the expansion energy that is lost in the conventional vapor-compression cycle, and is applicable to almost all vapor-compression refrigerating air conditioners, thus improving the efficiency of the refrigeration cycle. Concerning the application of the Ejector Cycle in truck-transport refrigerators, we released Ejector Cycle products for large and medium-size freezer trucks, which have been favorably accepted by customers in 2003. Simultaneously we also developed the domestic water supply system using heat pump with natural refrigerant (CO{sub 2}). We developed a new Ejector Cycle, completed in 2007 a cool box which uses the refrigeration cycle of the mobile air-conditioning system to cool drinks and the commercial compact refrigerator. In 2008 a domestic water supply heat pump system using a heat pump with the natural refrigerant CO{sub 2} and the next-generation Ejector Cycle II that substantially improves performance was brought to the market. A new generation of Ejector Cycle is under development which will significantly improve the efficiency of mobile air conditioning systems (orig.)

  14. Acoustic field characteristics and performance analysis of a looped travelling-wave thermoacoustic refrigerator

    International Nuclear Information System (INIS)

    Jin, T.; Yang, R.; Wang, Y.; Feng, Y.; Tang, K.

    2016-01-01

    Highlights: • Key issues for a highly efficient thermoacoustic conversion are analyzed. • A looped thermoacoustic refrigerator with one engine stage and one refrigerator stage is proposed. • Effective refrigeration powered by heat sources below 250 °C is demonstrated in the simulation. • Impact of cooling/heating temperatures on system performance is analyzed in view of acoustic field. - Abstract: This paper focuses on a looped travelling-wave thermoacoustic refrigerator powered by thermal energy. Based on a simplified model for the regenerator, key issues for a highly efficient thermoacoustic conversion, including both thermal-to-acoustic and heat-pumping processes, are summarized. A looped travelling-wave thermoacoustic refrigerator with one engine stage and one refrigerator stage is proposed, with emphasis on high normalized acoustic impedance, sufficient volumetric velocity and appropriate phase relation close to travelling wave in the regenerators of both engine and refrigerator. Simulation results indicate that for the ambient temperature of 30 °C, the looped travelling-wave thermoacoustic refrigerator can be powered by the heat at 210–250 °C to achieve the refrigeration at −3 °C with the overall coefficient of performance above 0.4 and the relative Carnot coefficient of performance over 13%. The characteristics of the acoustic field inside the loop configuration are analyzed in detail to reveal the operation mechanism of the looped travelling-wave thermoacoustic refrigerator. Additional analyses are conducted on the impact of the cooling and the heating temperatures, which are of great concern to the refrigeration applications and the utilization of low-grade thermal energy.

  15. The performance of solar heat pump with non-freon refrigerant CF{sub 3}CH{sub 2}F(R-134a) for school classroom heating [II

    Energy Technology Data Exchange (ETDEWEB)

    Sun, K.H.; Jung, H.C. [Kyung Hee University, Seoul (Korea, Republic of); Kim, K.S. [Daebul University (Korea, Republic of)

    1997-03-01

    The goal of this paper is to measure and compare the performance of solar heat pump for school classroom heating. To accomplish the goal, solar heat pump with aluminum roll bond type evaporator and indoor heat exchanger(condenser) was built and fully instrumented with thermocouples and pressure transducers etc. The test results showed that the COP and capacity of R-134a(CF{sub 3}CH{sub 2}F) were higher than those of R-12(CF{sub 2}Cl{sub 2}). The solar heat pump system for room heating was designed to show the best efficiency that the room temperature make 18{approx}20{sup o} C and 23{approx}25{sup o} C in Seoul during November, December, and January. (author) 12 refs., 4 figs., 2 tabs.

  16. Evaporation of refrigerant HFC 407C on plain tubes or at an improved surface; Evaporation du refrigerant HFC 407C sur des tubes lisses ou a surface amelioree

    Energy Technology Data Exchange (ETDEWEB)

    Zuercher, O.; Favrat, D.; Thome, J. R.; Kattan, N.; Nidegger, E. [Ecole polytechnique federale, Lab. d` energetique industrielle, Lausanne (Switzerland)

    1996-11-15

    The substitution of CFC refrigerants in refrigeration systems, heat pumps and organic Rankine cycles for heat recovery, requires good methods for predicting heat transfer of substitute fluids. The measurements in the LENI test facility (concentric tubes with water flowing in a counter-current flow) with HFC 407C, HFC 134a, HCFC 123, HFC 404a and HFC/HCFC 402A provide a new data bank for new refrigerants, and allow a coherent comparison with old refrigerants CFC 11, CFC 12, CFC/HCFC 502 and with existing correlations. The existing correlations were found to be inadequate. Because of this work, an improved flow pattern map and flow boiling model were developed, which resulted in a substantial progress in the accurate predict of heat transfer in plain, horizontal tubes for refrigerants without oil. The Kattan et al. correlation was programmed to calculate and compare predicted heat transfer coefficients to the new HFC 407C test data. The flow pattern map proposed by Kattan et al. was also programmed and compared to flow regimes observed for HFC 407C. It predicted the HFC 407C flow pattern data quite accurately. The original objective of the HFC 407C measurements was the validation of the Kattan et al. correlation applied to a zeotropic refrigerant blend. Local flow boiling heat transfer coefficients were measured for HFC 407C evaporating inside a microfin and a plain tube. In addition, microfin heat transfer augmentation relative to a plain tube was investigated. The presence of oil in the evaporator had a complex effect on heat transfer coefficients. Local flow boiling heat transfer coefficients were measured for refrigerant HFC 407C ester oil mixtures (Mobil EAL Arctic 68). A new thermodynamic approach for modeling mixtures of zeotropic refrigerant blends and lubricating oils was also developed. (author) figs., tabs., 14 refs.

  17. Flammability Indices for Refrigerants

    Science.gov (United States)

    Kataoka, Osami

    This paper introduces a new index to classify flammable refrigerants. A question on flammability indices that ASHRAE employs arose from combustion test results of R152a and ammonia. Conventional methods of not only ASHRAE but also ISO and Japanese High-pressure gas safety law to classify the flammability of refrigerants are evaluated to show why these methods conflict with the test results. The key finding of this paper is that the ratio of stoichiometric concentration to LFL concentration (R factor) represents the test results most precisely. In addition, it has excellent correlation with other flammability parameters such as flame speed and pressure rise coefficient. Classification according to this index gives reasonable flammability order of substances including ammonia, R152a and carbon monoxide. Theoretical background why this index gives good correlation is also discussed as well as the insufficient part of this method.

  18. Quantum-Circuit Refrigerator

    Science.gov (United States)

    MöTtöNen, Mikko; Tan, Kuan Y.; Masuda, Shumpei; Partanen, Matti; Lake, Russell E.; Govenius, Joonas; Silveri, Matti; Grabert, Hermann

    Quantum technology holds great potential in providing revolutionizing practical applications. However, fast and precise cooling of the functional quantum degrees of freedom on demand remains a major challenge in many solid-state implementations, such as superconducting circuits. We demonstrate direct cooling of a superconducting resonator mode using voltage-controllable quantum tunneling of electrons in a nanoscale refrigerator. In our first experiments on this type of a quantum-circuit refrigerator, we measure the drop in the mode temperature by electron thermometry at a resistor which is coupled to the resonator mode through ohmic losses. To eliminate unwanted dissipation, we remove the probe resistor and directly observe the power spectrum of the resonator output in agreement with the so-called P(E) theory. We also demonstrate in microwave reflection experiments that the internal quality factor of the resonator can be tuned by orders of magnitude. In the future, our refrigerator can be integrated with different quantum electric devices, potentially enhancing their performance. For example, it may prove useful in the initialization of superconducting quantum bits and in dissipation-assisted quantum annealing. We acknowledge European Research Council Grant SINGLEOUT (278117) and QUESS (681311) for funding.

  19. Acceleration/heating of plasma on auroral field lines: preliminary results from the Viking satellite

    International Nuclear Information System (INIS)

    Lundin, R.

    1988-01-01

    In this report, a review of the first results obtained from the particle experiment on board the Viking spacecraft will be given. During the first part of the Viking mission, the orbit was suitable for high-altitude measurements (up to ∼ 13500 km) in the dayside oval and the cusp/cleft region. Thus, some emphasis will be put on processes occurring in the dayside auroral region. On the basis of more than 100 Viking traversals of the cusp and cleft it is suggested that these regions can be identified by some regular characteristics in the particle data. The cusp has a continuous presence of solar wind plasma, affected mainly by convection and containing modest plasma energization. Conversely, the cleft is characterized by extensive plasma energization, and strong field aligned current sheets. Temporal injections of solar wind plasma are frequently observed in the cleft. A distinguishing characteristic of the Viking charged particle experiment is the energy and angular resolution. Thus, the fine-structure of narrow particle beams and conical distributions of both electrons and ions can be determined. This enables very detailed studies of the plasma acceleration processes along auroral field lines. Some examples of accelerated plasma populations and their related energy and angular distribution will be presented. The observations are compared with existing theories of auroral plasma heating and acceleration processes

  20. Cryo-refrigerators for CNS applications

    International Nuclear Information System (INIS)

    Clausen, J.; Lesser, J.; Sebastianutto, R.

    2001-01-01

    Cryo-refrigeration plants for cold neutron sources belong to the field of auxiliary plants or utility facilities of the reactor. In general, they are classified as non-nuclear and serve to dissipate the heat generated in the liquid hydrogen or deuterium from moderating the neutrons of the cold neutron source. Cryo-refrigeration plants for the temperature range of 20 K supply either refrigeration at constant temperature by means of evaporating the cryogenic coolant (usually hydrogen) or, as usual with cold sources, in a specific temperature range by means of warming-up the cryogenic coolant (usually helium) in the moderator or heat exchanger (condensation or subcooling of the deuterium). The operator's requirements to a refrigeration plant are, first of all, that the plant adjusts itself - at low-maintenance or maintenance-free - to the various operation modes at best thermodynamic efficiencies and that it offers as much operating convenience and operating safety as possible. Additional requirements are short times for cool-down, capacity adjustment, stand-by operation in order to avoid poisoning of the cold source and further operational requirements. However, these requirements are limited by mechanics, thermodynamics and financial means. For this reason, for each application a technical solution must be found which is optimally adapted to the competing requirements and which is based on a standard product of the manufacturer, if possible. The operator's different requirements have to be taken in account with regard to the design of the plant and choice of the components; economic aspects in addition also have to be considered. Wherever possible, proven standard components should be used. (orig.)

  1. Transport Refrigeration Technician: Apprenticeship Course Outline. Apprenticeship and Industry Training. 4112

    Science.gov (United States)

    Alberta Advanced Education and Technology, 2012

    2012-01-01

    The graduate of the Transport Refrigeration Technician apprenticeship program is a certified journeyperson who will be able: (1) to diagnose repair, maintain and operate transport refrigeration equipment used to heat or cool the load as well as of diesel engines, APUs and other prime movers; (2) to use tools and equipment in order to carry out…

  2. 77 FR 76825 - Energy Conservation Program: Certification of Commercial and Industrial HVAC, Refrigeration and...

    Science.gov (United States)

    2012-12-31

    ... Energy Conservation Program: Certification of Commercial and Industrial HVAC, Refrigeration and Water... provisions for commercial refrigeration equipment; commercial heating, ventilating, air-conditioning (HVAC...; commercial HVAC equipment; commercial WH equipment; and walk-in coolers and freezers (June 30 Final Rule). 76...

  3. CONCEPT OF AUTOMATIC CONTROL SYSTEM FOR IMPROVING THE EFFICIENCY OF THE ABSORPTION REFRIGERATING UNITS

    Directory of Open Access Journals (Sweden)

    O. Titlova

    2016-12-01

    Full Text Available The general concept of the automatic control systems constructing for increasing the efficiency of the artificial cold production process in the absorption refrigerating units is substantiated. The described automatic control systems provides necessary degree of the ammonia vapor purification from the water in all absorption refrigerating units modes and minimizes heat loss from the dephlegmator surface.

  4. Satellite Images and Gaussian Parameterization for an Extensive Analysis of Urban Heat Islands in Thailand

    Directory of Open Access Journals (Sweden)

    Chaiyapon Keeratikasikorn

    2018-04-01

    Full Text Available For the first time, an extensive study of the surface urban heat island (SUHI in Thailand’s six major cities is reported, using 728 MODIS (MODerate Resolution Imaging Spectroradiometer images for each city. The SUHI analysis was performed at three timescales—diurnal, seasonal, and multiyear. The diurnal variation is represented by the four MODIS passages (10:00, 14:00, 22:00, and 02:00 local time and the seasonal variation by summer and winter maps, with images covering a 14-year interval (2003–2016. Also, 126 Landsat scenes were processed to classify and map land cover changes for each city. To analyze and compare the SUHI patterns, a least-square Gaussian fitting method has been applied and the corresponding empirical metrics quantified. Such an approach represents, when applicable, an efficient quantitative tool to perform comparisons that a visual inspection of a great number of maps would not allow. Results point out that SUHI does not show significant seasonality differences, while SUHI in the daytime is a more evident phenomenon with respect to nighttime, mainly due to solar forcing and intense human activities and traffic. Across the 14 years, the biggest city, Bangkok, shows the highest SUHI maximum intensities during daytime, with values ranging between 4 °C and 6 °C; during nighttime, the intensities are rather similar for all the six cities, between 1 °C and 2 °C. However, these maximum intensities are not correlated with the urban growth over the years. For each city, the SUHI spatial extension represented by the Gaussian footprint is generally not affected by the urban area sprawl across the years, except for Bangkok and Chiang Mai, whose daytime SUHI footprints show a slight increase over the years. Orientation angle and central location of the fitted surface also provide information on the SUHI layout in relation to the land use of the urban texture.

  5. Quantum refrigerators and the third law of thermodynamics.

    Science.gov (United States)

    Levy, Amikam; Alicki, Robert; Kosloff, Ronnie

    2012-06-01

    The rate of temperature decrease of a cooled quantum bath is studied as its temperature is reduced to absolute zero. The third law of thermodynamics is then quantified dynamically by evaluating the characteristic exponent ζ of the cooling process dT(t)/dt∼-T^{ζ} when approaching absolute zero, T→0. A continuous model of a quantum refrigerator is employed consisting of a working medium composed either by two coupled harmonic oscillators or two coupled two-level systems. The refrigerator is a nonlinear device merging three currents from three heat baths: a cold bath to be cooled, a hot bath as an entropy sink, and a driving bath which is the source of cooling power. A heat-driven refrigerator (absorption refrigerator) is compared to a power-driven refrigerator. When optimized, both cases lead to the same exponent ζ, showing a lack of dependence on the form of the working medium and the characteristics of the drivers. The characteristic exponent is therefore determined by the properties of the cold reservoir and its interaction with the system. Two generic heat bath models are considered: a bath composed of harmonic oscillators and a bath composed of ideal Bose/Fermi gas. The restrictions on the interaction Hamiltonian imposed by the third law are discussed. In the Appendices, the theory of periodically driven open systems and its implication for thermodynamics are outlined.

  6. Dilution Refrigeration of Multi-Ton Cold Masses

    CERN Document Server

    Wikus, P; CERN. Geneva

    2007-01-01

    Dilution refrigeration is the only means to provide continuous cooling at temperatures below 250 mK. Future experiments featuring multi-ton cold masses require a new generation of dilution refrigeration systems, capable of providing a heat sink below 10 mK at cooling powers which exceed the performance of present systems considerably. This thesis presents some advances towards dilution refrigeration of multi-ton masses in this temperature range. A new method using numerical simulation to predict the cooling power of a dilution refrigerator of a given design has been developed in the framework of this thesis project. This method does not only allow to take into account the differences between an actual and an ideal continuous heat exchanger, but also to quantify the impact of an additional heat load on an intermediate section of the dilute stream. In addition, transient behavior can be simulated. The numerical model has been experimentally verified with a dilution refrigeration system which has been designed, ...

  7. A review of magnetic heat pump technology

    International Nuclear Information System (INIS)

    Barclay, J.A.

    1990-01-01

    The area of technology classified as heat pumps generally refers to refrigerators, heat pumps and heat engines. This review is restricted to the literature on magnetic refrigerators and magnetic heat pumps which are referred to interchangeably. Significant progress has been made on the development of engineering prototypes of cryogenic, nonregenerative magnetic refrigerators utilizing conductive heat transfer in the 0.1 K to 20 K temperature range. Advances have also been made in analysis of regenerative magnetic refrigerators and heat pumps utilizing the active magnetic regeneration (AMR) concept. Units based on AMR are being modeled, designed and/or built to operate in various temperature ranges including 1.8-4.5 K, 4-15 K, 15-85 K, and 270-320 K. The near room temperature units have been scaled to 50 kW as both refrigerators and heat pumps. The progress of magnetic refrigeration over the last three years is summarized and discussed

  8. Spatio-temporal Assessment of Land Use/ Land Cover Dynamics and Urban Heat Island of Jaipur City using Satellite Data

    Science.gov (United States)

    Jalan, S.; Sharma, K.

    2014-11-01

    Urban Heat Island (UHI) refers to the phenomena of higher surface temperature occurring in urban areas as compared to the surrounding countryside attributable to urbanization. Spatio-temporal changes in UHI can be quantified through Land Surface Temperature (LST) derived from satellite imageries. Spatial variations in LST occur due to complexity of land surface - combination of impervious surface materials, vegetation, exposed soils as well as water surfaces. Jaipur city has observed rapid urbanization over the last decade. Due to rising population pressure the city has expanded considerably in areal extent and has also observed substantial land use/land cover (LULC) changes. The paper aims to determine changes in the LST and UHI phenomena for Jaipur city over the period from 2000 to 2011 and analyzes the spatial distribution and temporal variation of LST in context of changes in LULC. Landsat 7 ETM+ (2000) and Landsat 5 TM (2011) images of summer season have been used. Results reveal that Jaipur city has witnessed considerable growth in built up area at the cost of greener patches over the last decade, which has had clear impact on variation in LST. There has been an average rise of 2.99 °C in overall summer temperature. New suburbs of the city record 2° to 4 °C increase in LST. LST change is inversely related to change in vegetation cover and positively related to extent of built up area. The study concludes that UHI of Jaipur city has intensified and extended over new areas.

  9. IDENTIFYING LOCAL SCALE CLIMATE ZONES OF URBAN HEAT ISLAND FROM HJ-1B SATELLITE DATA USING SELF-ORGANIZING MAPS

    Directory of Open Access Journals (Sweden)

    C. Z. Wei

    2016-10-01

    Full Text Available With the increasing acceleration of urbanization, the degeneration of the environment and the Urban Heat Island (UHI has attracted more and more attention. Quantitative delineation of UHI has become crucial for a better understanding of the interregional interaction between urbanization processes and the urban environment system. First of all, our study used medium resolution Chinese satellite data-HJ-1B as the Earth Observation data source to derive parameters, including the percentage of Impervious Surface Areas, Land Surface Temperature, Land Surface Albedo, Normalized Differential Vegetation Index, and object edge detector indicators (Mean of Inner Border, Mean of Outer border in the city of Guangzhou, China. Secondly, in order to establish a model to delineate the local climate zones of UHI, we used the Principal Component Analysis to explore the correlations between all these parameters, and estimate their contributions to the principal components of UHI zones. Finally, depending on the results of the PCA, we chose the most suitable parameters to classify the urban climate zones based on a Self-Organization Map (SOM. The results show that all six parameters are closely correlated with each other and have a high percentage of cumulative (95% in the first two principal components. Therefore, the SOM algorithm automatically categorized the city of Guangzhou into five classes of UHI zones using these six spectral, structural and climate parameters as inputs. UHI zones have distinguishable physical characteristics, and could potentially help to provide the basis and decision support for further sustainable urban planning.

  10. An Empirical Orthogonal Function-Based Algorithm for Estimating Terrestrial Latent Heat Flux from Eddy Covariance, Meteorological and Satellite Observations.

    Science.gov (United States)

    Feng, Fei; Li, Xianglan; Yao, Yunjun; Liang, Shunlin; Chen, Jiquan; Zhao, Xiang; Jia, Kun; Pintér, Krisztina; McCaughey, J Harry

    2016-01-01

    Accurate estimation of latent heat flux (LE) based on remote sensing data is critical in characterizing terrestrial ecosystems and modeling land surface processes. Many LE products were released during the past few decades, but their quality might not meet the requirements in terms of data consistency and estimation accuracy. Merging multiple algorithms could be an effective way to improve the quality of existing LE products. In this paper, we present a data integration method based on modified empirical orthogonal function (EOF) analysis to integrate the Moderate Resolution Imaging Spectroradiometer (MODIS) LE product (MOD16) and the Priestley-Taylor LE algorithm of Jet Propulsion Laboratory (PT-JPL) estimate. Twenty-two eddy covariance (EC) sites with LE observation were chosen to evaluate our algorithm, showing that the proposed EOF fusion method was capable of integrating the two satellite data sets with improved consistency and reduced uncertainties. Further efforts were needed to evaluate and improve the proposed algorithm at larger spatial scales and time periods, and over different land cover types.

  11. Research and Development Roadmap For Next-Generation Low-Global Warming Potential Refrigerants

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2011-07-01

    The Department of Energy commissioned this roadmap to establish a set of high-priority research and development (R&D) activities that will accelerate the transition to low-GWP refrigerants across the entire heating, ventilation, air-conditioning and refrigeration (HVAC&R) industry. The schedule of R&D activities occurs within an accelerated five-year timeframe, and covers several prominent equipment types. The roadmap is organized around four primary objectives to: assess and mitigate safety risks, characterize refrigerant properties, understand efficiency and environmental tradeoffs, and support new refrigerant and equipment development.

  12. Coefficient of performance of Stirling refrigerators

    Science.gov (United States)

    E Mungan, Carl

    2017-09-01

    Stirling coolers transfer heat in or out of the working fluid during all four stages of their operation, and their coefficient of performance depends on whether the non-isothermal heat exchanges are performed reversibly or irreversibly. Both of these possibilities can in principle be arranged. Notably, if the working fluid is an ideal gas, the input of energy in the form of heat during one isochoric step is equal in magnitude to the output during the other isochoric step in the cycle. The theoretical performance of the fridge can then attain the reversible Carnot limit if a regenerator is used, which is a high heat capacity material through which the gas flows. Various Stirling refrigerator configurations are analysed in this article at a level of presentation suitable for an introductory undergraduate thermodynamics course.

  13. 78 FR 15653 - Notice of Intent To Form the Commercial HVAC, WH, and Refrigeration Certification Working Group...

    Science.gov (United States)

    2013-03-12

    ... DEPARTMENT OF ENERGY 10 CFR Part 429 Notice of Intent To Form the Commercial HVAC, WH, and... Requirements for Commercial HVAC, WH, and Refrigeration Equipment AGENCY: Office of Energy Efficiency and... commercial heating, ventilation, and air-conditioning (HVAC), water heating (WH), and refrigeration equipment...

  14. Food transport refrigeration - Approaches to reduce energy consumption and environmental impacts of road transport

    International Nuclear Information System (INIS)

    Tassou, S.A.; De-Lille, G.; Ge, Y.T.

    2009-01-01

    Food transport refrigeration is a critical link in the food chain not only in terms of maintaining the temperature integrity of the transported products but also its impact on energy consumption and CO 2 emissions. This paper provides a review of (a) current approaches in road food transport refrigeration, (b) estimates of their environmental impacts, and (c) research on the development and application of alternative technologies to vapour compression refrigeration systems that have the potential to reduce the overall energy consumption and environmental impacts. The review and analysis indicate that greenhouse gas emissions from conventional diesel engine driven vapour compression refrigeration systems commonly employed in food transport refrigeration can be as high as 40% of the greenhouse gas emissions from the vehicle's engine. For articulated vehicles over 33 ton, which are responsible for over 80% of refrigerated food transportation in the UK, the reject heat available form the engine is sufficient to drive sorption refrigeration systems and satisfy most of the refrigeration requirements of the vehicle. Other promising technologies that can lead to a reduction in CO 2 emissions are air cycle refrigeration and hybrid systems in which conventional refrigeration technologies are integrated with thermal energy storage. For these systems, however, to effectively compete with diesel driven vapour compression systems, further research and development work is needed to improve their efficiency and reduce their weight

  15. THERMODYNAMIC PROPERTIES OF SELECTED HFC REFRIGERANTS

    Science.gov (United States)

    Hydrofluorocarbon (HFC) refrigerants are possible alternatives to replace ozone-depleting chlorofluorocarbon and hydrochlorofluorocarbon (HCFC) refrigerants. The flammability of a proposed new refrigerant is a major consideration in assessing its utility for a particular applicat...

  16. Industrial applications of refrigeration. General considerations; Applications industrielles du froid. Generalites

    Energy Technology Data Exchange (ETDEWEB)

    Marvillet, Ch. [Ecole Centrale de Lyon, 69 - Ecully (France); Groupement pour la Recherche sur les Echangeurs Thermiques, GRETh (France)

    2001-10-01

    The refrigeration process consists in the lowering of the temperature of a product or of a process below the ambient temperature. Thus, the refrigeration process implies a heat absorption process for the production of coldness. Two ways of coldness production are considered: the mechanical refrigeration using compression or absorption cycle machineries, and the cryogenic refrigeration which requires the use of industrial fluids like liquid nitrogen, helium or CO{sub 2}. This article presents the different functions of refrigeration in industrial processes and the effects of temperature on inert or living matter (influence of temperature on the physical properties, thermodynamic state, and physico-chemical transformations of solids, bodies and substances, influence of temperature on the transformation processes of food products, mechanical refrigeration and mastery of fermentation). (J.S.)

  17. The LSST Camera 500 watt -130 degC Mixed Refrigerant Cooling System

    Energy Technology Data Exchange (ETDEWEB)

    Bowden, Gordon B.; Langton, Brian J.; /SLAC; Little, William A.; /MMR-Technologies, Mountain View, CA; Powers, Jacob R; Schindler, Rafe H.; /SLAC; Spektor, Sam; /MMR-Technologies, Mountain View, CA

    2014-05-28

    The LSST Camera has a higher cryogenic heat load than previous CCD telescope cameras due to its large size (634 mm diameter focal plane, 3.2 Giga pixels) and its close coupled front-end electronics operating at low temperature inside the cryostat. Various refrigeration technologies are considered for this telescope/camera environment. MMR-Technology’s Mixed Refrigerant technology was chosen. A collaboration with that company was started in 2009. The system, based on a cluster of Joule-Thomson refrigerators running a special blend of mixed refrigerants is described. Both the advantages and problems of applying this technology to telescope camera refrigeration are discussed. Test results from a prototype refrigerator running in a realistic telescope configuration are reported. Current and future stages of the development program are described. (auth)

  18. Improvement of two-stage GM refrigerator performance using a hybrid regenerator

    International Nuclear Information System (INIS)

    Ke, G.; Makuuchi, H.; Hashimoto, T.; Onishi, A.; Li, R.; Satoh, T.; Kanazawa, Y.

    1994-01-01

    To improve the performance of two-stage GM refrigerators, a hybrid regenerator with magnetic materials of Er 3 Ni and ErNi 0.9 Co 0.1 was used in the 2nd stage regenerator because of its large heat exchange capacity. The largest refrigeration capacity achieved with the hybrid regenerator was 0.95W at helium liquefied temperature of 4.2K. This capacity is 15.9% greater than the 0.82W refrigerator with only Er 3 Ni as the 2nd regenerator material. Use of the hybrid regenerator not only increases the refrigeration capacity at 4.2K, but also allows the 4K GM refrigerator to be used with large 1st stage refrigeration capacity, thus making it more practical

  19. Artificial neural network analysis of triple effect absorption refrigeration systems

    Energy Technology Data Exchange (ETDEWEB)

    Hajizadeh Aghdam, A. [Department of Mechanical Engineering, Islamic Azad University (Iran, Islamic Republic of)], email: a.hajizadeh@iaukashan.ac.ir; Nazmara, H.; Farzaneh, B. [Department of Mechanical Engineering, University of Tabriz (Iran, Islamic Republic of)], email: h.nazmara@nioec.org, email: b_farzaneh_ms@yahoo.com

    2011-07-01

    In this study, artificial neural networks are utilized to predict the performance of triple effect series and parallel flow absorption refrigeration systems, with lithium bromide/water as the working fluid. Important parameters such as high generator and evaporator temperatures were varied and their effects on the performance characteristics of the refrigeration unit were observed. Absorption refrigeration systems make energy savings possible because they can use heat energy to produce cooling, in place of the electricity used for conventional vapour compression chillers. In addition, non-conventional sources of energy (such as solar, waste heat, and geothermal) can be utilized as their primary energy input. Moreover, absorption units use environmentally friendly working fluid pairs instead of CFCs and HCFCs, which affect the ozone layer. Triple effect absorption cycles were analysed. Results apply for both series and parallel flow systems. A relative preference for parallel-flow over series-flow is also shown.

  20. Effect of evaporator temperature on vapor compression refrigeration system

    Directory of Open Access Journals (Sweden)

    Abdullah A.A.A. Al-Rashed

    2011-12-01

    Full Text Available This paper presents a comparable evaluation of R600a (isobutane, R290 (propane, R134a, R22, for R410A, and R32 an optimized finned-tube evaporator, and analyzes the evaporator effect on the system coefficient of performance (COP. Results concerning the response of a refrigeration system simulation software to an increase in the amount of oil flowing with the refrigerant are presented. It is shown that there is optima of the apparent overheat value, for which either the exchanged heat or the refrigeration coefficient of performance (COP is maximized: consequently, it is not possible to optimize both the refrigeration COP and the evaporator effect. The obtained evaporator optimization results were incorporated in a conventional analysis of the vapor compression system. For a theoretical cycle analysis without accounting for evaporator effects, the COP spread for the studied refrigerants was as high as 11.7%. For cycle simulations including evaporator effects, the COP of R290 was better than that of R22 by up to 3.5%, while the remaining refrigerants performed approximately within a 2% COP band of the R22 baseline for the two condensing temperatures considered.

  1. A flexible numerical model to study an active magnetic refrigerator for near room temperature applications

    Energy Technology Data Exchange (ETDEWEB)

    Aprea, Ciro; Maiorino, Angelo [Department of Mechanical Engineering, University of Salerno, Via Ponte Don Melillo 1, 84084 Fisciano (Salerno) (Italy)

    2010-08-15

    Magnetic refrigeration is an emerging technology based on the magnetocaloric effect in solid-state refrigerants. This technology offers a smaller global environmental impact than the refrigeration obtained by means of the classical vapor compression machines operating with fluids such as HFCs. The Active Magnetic Regenerative Refrigeration (AMRR) is currently the most studied ant tested magnetic cycle. It combines the regenerative properties of a high specific heat solid porous matrix with the ability of performing thermo-magnetic cycles thanks to the magnetocaloric property of the refrigerant; while a fluid pulsing through the regenerator works as a heat transfer medium. An active magnetic regenerator can provide larger temperature spans making up for the local small temperature variation of the refrigerant. In the present paper, a practical model for predicting the performance and efficiency of an AMRR cycle has been developed. The model evaluates both the refrigerant properties and the entire cycle of an AMR operating in conformity with a Brayton regenerative cycle. The magnetocaloric material of choice is gadolinium, while the heat transfer medium is liquid water. With this model can be predicted the refrigeration capacity, the power consumption and consequently the Coefficient of Performance. The results show a greater COP when compared to a classical vapor compression plant working between the same temperature levels. (author)

  2. A flexible numerical model to study an active magnetic refrigerator for near room temperature applications

    International Nuclear Information System (INIS)

    Aprea, Ciro; Maiorino, Angelo

    2010-01-01

    Magnetic refrigeration is an emerging technology based on the magnetocaloric effect in solid-state refrigerants. This technology offers a smaller global environmental impact than the refrigeration obtained by means of the classical vapor compression machines operating with fluids such as HFCs. The Active Magnetic Regenerative Refrigeration (AMRR) is currently the most studied ant tested magnetic cycle. It combines the regenerative properties of a high specific heat solid porous matrix with the ability of performing thermo-magnetic cycles thanks to the magnetocaloric property of the refrigerant; while a fluid pulsing through the regenerator works as a heat transfer medium. An active magnetic regenerator can provide larger temperature spans making up for the local small temperature variation of the refrigerant. In the present paper, a practical model for predicting the performance and efficiency of an AMRR cycle has been developed. The model evaluates both the refrigerant properties and the entire cycle of an AMR operating in conformity with a Brayton regenerative cycle. The magnetocaloric material of choice is gadolinium, while the heat transfer medium is liquid water. With this model can be predicted the refrigeration capacity, the power consumption and consequently the Coefficient of Performance. The results show a greater COP when compared to a classical vapor compression plant working between the same temperature levels.

  3. Energy optimisation of domestic refrigerators

    DEFF Research Database (Denmark)

    Jakobsen, Arne; Rasmussen, Bjarne D.

    1998-01-01

    This paper describes the main results of a research project with the objective of reducing the energy consumption of domestic refrigerators by increasing the efficiency of the refrigeration system. The improvement of the system efficiency was to be obtained by:1) Introducing continuous operation ...

  4. Parametric analysis and optimization for a combined power and refrigeration cycle

    International Nuclear Information System (INIS)

    Wang Jiangfeng; Dai Yiping; Gao Lin

    2008-01-01

    A combined power and refrigeration cycle is proposed, which combines the Rankine cycle and the absorption refrigeration cycle. This combined cycle uses a binary ammonia-water mixture as the working fluid and produces both power output and refrigeration output simultaneously with only one heat source. A parametric analysis is conducted to evaluate the effects of thermodynamic parameters on the performance of the combined cycle. It is shown that heat source temperature, environment temperature, refrigeration temperature, turbine inlet pressure, turbine inlet temperature, and basic solution ammonia concentration have significant effects on the net power output, refrigeration output and exergy efficiency of the combined cycle. A parameter optimization is achieved by means of genetic algorithm to reach the maximum exergy efficiency. The optimized exergy efficiency is 43.06% under the given condition

  5. THERMODYNAMIC ANALYSIS AND SIMULATION OF A NEW COMBINED POWER AND REFRIGERATION CYCLE USING ARTIFICIAL NEURAL NETWORK

    Directory of Open Access Journals (Sweden)

    Hossein Rezvantalab

    2011-01-01

    Full Text Available In this study, a new combined power and refrigeration cycle is proposed, which combines the Rankine and absorption refrigeration cycles. Using a binary ammonia-water mixture as the working fluid, this combined cycle produces both power and refrigeration output simultaneously by employing only one external heat source. In order to achieve the highest possible exergy efficiency, a secondary turbine is inserted to expand the hot weak solution leaving the boiler. Moreover, an artificial neural network (ANN is used to simulate the thermodynamic properties and the relationship between the input thermodynamic variables on the cycle performance. It is shown that turbine inlet pressure, as well as heat source and refrigeration temperatures have significant effects on the net power output, refrigeration output and exergy efficiency of the combined cycle. In addition, the results of ANN are in excellent agreement with the mathematical simulation and cover a wider range for evaluation of cycle performance.

  6. Optimization of Multi-layer Active Magnetic Regenerator towards Compact and Efficient Refrigeration

    DEFF Research Database (Denmark)

    Lei, Tian; Engelbrecht, Kurt; Nielsen, Kaspar Kirstein

    2016-01-01

    Magnetic refrigerators can theoretically be more efficient than current vapor compression systems and use no vapor refrigerants with global warming potential. The core component, the active magnetic regenerator (AMR) operates based on the magnetocaloric effect of magnetic materials and the heat r....... In addition, simulations are carried out to investigate the potential of applying nanofluid in future magnetic refrigerators.......Magnetic refrigerators can theoretically be more efficient than current vapor compression systems and use no vapor refrigerants with global warming potential. The core component, the active magnetic regenerator (AMR) operates based on the magnetocaloric effect of magnetic materials and the heat...... their Curie temperature. Simulations are implemented to investigate how to layer the FOPT materials for obtaining higher cooling capacity. Moreover, based on entropy generation minimization, optimization of the regenerator geometry and related operating parameters is presented for improving the AMR efficiency...

  7. Regulating Power from Supermarket Refrigeration

    DEFF Research Database (Denmark)

    O'Connell, Niamh; Madsen, Henrik; Pinson, Pierre

    2014-01-01

    the Danfoss refrigeration test centre. The complexities of modelling demand response are demonstrated through simulation. Simulations are conducted by placing the identified model in a direct-control demand response architecture, with power reference tracking using model predictive control. The energylimited......This paper presents an analysis of the demand response capabilities of a supermarket refrigeration system, with a particular focus on the suitability for participation in the regulating power market. An ARMAX model of a supermarket refrigeration system is identified using experimental data from...... nature of demand response from refrigeration is identified as the key consideration when considering participation in the regulating power market. It is demonstrated that by restricting the operating regions of the supermarket refrigeration system, a simple relationship can be found between the available...

  8. Does quality control matter? Surface urban heat island intensity variations estimated by satellite-derived land surface temperature products

    Science.gov (United States)

    Lai, Jiameng; Zhan, Wenfeng; Huang, Fan; Quan, Jinling; Hu, Leiqiu; Gao, Lun; Ju, Weimin

    2018-05-01

    The temporally regular and spatially comprehensive monitoring of surface urban heat islands (SUHIs) have been extremely difficult, until the advent of satellite-based land surface temperature (LST) products. However, these LST products have relatively higher errors compared to in situ measurements. This has resulted in comparatively inaccurate estimations of SUHI indicators and, consequently, may have distorted interpretations of SUHIs. Although reports have shown that LST qualities are important for SUHI interpretations, systematic investigations of the response of SUHI indicators to LST qualities across cities with dissimilar bioclimates are rare. To address this issue, we chose eighty-six major cities across mainland China and analyzed SUHI intensity (SUHII) derived from Moderate Resolution Imaging Spectroradiometer (MODIS) LST data. The LST-based SUHII differences due to inclusion or exclusion of MODIS quality control (QC) flags (i.e., ΔSUHII) were evaluated. Our major findings included, but are not limited to, the following four aspects: (1) SUHIIs can be significantly impacted by MODIS QC flags, and the associated QC-induced ΔSUHIIs generally accounted for 24.3% (29.9%) of the total SUHII value during the day (night); (2) the ΔSUHIIs differed between seasons, with considerable differences between transitional (spring and autumn) and extreme (summer and winter) seasons; (3) significant discrepancies also appeared among cities located in northern and southern regions, with northern cities often possessing higher annual mean ΔSUHIIs. The internal variations of ΔSUHIIs within individual cities also showed high heterogeneity, with ΔSUHII variations that generally exceeded 5.0 K (3.0 K) in northern (southern) cities; (4) ΔSUHIIs were negatively related to SUHIIs and cloud cover percentages (mostly in transitional seasons). No significant relationship was found in the extreme seasons. Our findings highlight the need to be extremely cautious when using LST

  9. TORE SUPRA 300 W - 1.75 K refrigerator report

    International Nuclear Information System (INIS)

    Gistau, G.M.; Bonneton, M.; Mart, J.W.

    1988-01-01

    The TORE SUPRA refrigerator is now installed and the acceptance tests have been completed. All equipment has performed above design levels. The liquid ring pumps and cold centrifugal compressors have run for more than 1000 hours. Commissioning and acceptance tests, including cooldown, variable heat load, unscheduled shutdown, power outage and automatic restart, and a 400-hour shakedown run, are described and evaluated

  10. Indoor unit for electric heat pump

    Science.gov (United States)

    Draper, R.; Lackey, R.S.; Fagan, T.J. Jr.; Veyo, S.E.; Humphrey, J.R.

    1984-05-22

    An indoor unit for an electric heat pump is provided in modular form including a refrigeration module, an air mover module, and a resistance heat package module, the refrigeration module including all of the indoor refrigerant circuit components including the compressor in a space adjacent the heat exchanger, the modules being adapted to be connected to air flow communication in several different ways as shown to accommodate placement of the unit in various orientations. 9 figs.

  11. A passive solar heater-refrigerator

    International Nuclear Information System (INIS)

    D'Isep, F.; Sertorio, L.

    1983-01-01

    In this paper it is studied the nonequilibrium thermodynamic steady-state behaviour of a model system representing a core surrounded by an envelope in which the envelope interacts with the solar radiation and with an external bath having a given temperature profile. The heat flow between core and envelope can be controlled by varying the thermal conductivity of their interface. It is shown that this system acts as a passive heat pump raising the core average temperature with respect to the average equilibrium value corresponding to a fixed value of the interface conductivity, at the same time flattening its oscillation in time. By changing the time dependence of the conductivity the system vice versa acts as a refrigerator. It is shown how the limits of this performance depend on the passive parameters such as surfaces, conductivities, heat capacities. The periodicity considered in this study is the daily cycle

  12. Dynamic Simulation of AN Helium Refrigerator

    Science.gov (United States)

    Deschildre, C.; Barraud, A.; Bonnay, P.; Briend, P.; Girard, A.; Poncet, J. M.; Roussel, P.; Sequeira, S. E.

    2008-03-01

    A dynamic simulation of a large scale existing refrigerator has been performed using the software Aspen Hysys®. The model comprises the typical equipments of a cryogenic system: heat exchangers, expanders, helium phase separators and cold compressors. It represents the 400 W @ 1.8 K Test Facility located at CEA—Grenoble. This paper describes the model development and shows the possibilities and limitations of the dynamic module of Aspen Hysys®. Then, comparison between simulation results and experimental data are presented; the simulation of cooldown process was also performed.

  13. Technology Application of Environmental Friendly Refrigeration (Green Refrigeration) on Cold Storage for Fishery Industry

    Science.gov (United States)

    Rasta, IM; Susila, IDM; Subagia, IWA

    2018-01-01

    The application of refrigeration technology to postharvest fishery products is an very important. Moreover, Indonesia is a tropical region with relatively high temperatures. Fish storage age can be prolonged with a decrease in temperature. Frozen fish can even be stored for several months. Fish freezing means preparing fish for storage in low-temperature cold storage. The working fluid used in cold storage to cool low-temperature chambers and throw heat into high-temperature environments is refrigerant. So far refrigerant used in cold storage is Hydrochloroflourocarbons (HCFC) that is R-22. Chlor is a gas that causes ODP (Ozone Depleting Potential), while Flour is a gas that causes GWP (Global Warming Potential). Government policy began in 2015 to implement Hydrochloroflourocarbons Phase-Out Management Plan. Hydrocarbon (HC) is an alternative substitute for R-22. HC-22 (propane ≥ 99.5%) has several advantages, among others: environmentally friendly, indicated by a zero ODP value, and GWP = 3 (negligible), thermophysical property and good heat transfer characteristics, vapor phase density Which is low, and good solubility with mineral lubricants. The use of HC-22 in cold storage is less than R-22. From the analysis results obtained, cold storage system using HC-22 has better performance and energy consumption is more efficient than the R-22.

  14. CFD-simulations of a 4π-contiuous-mode dilution refrigerator for the CB-ELSA experiment

    Energy Technology Data Exchange (ETDEWEB)

    Altfelde, Timo; Bornstein, Marcel; Dutz, Hartmut; Goertz, Stefan; Miebach, Roland; Reeve, Scott; Runkel, Stefan; Sommer, Marco; Streit, Benjamin [Physikalisches Institut, Bonn (Germany)

    2015-07-01

    The polarized target group at Bonn operates a dilution refrigerator for double polarization experiments at the Crystal Barrel in Bonn. To get high target polarizations and long relaxation times low temperatures are indispensable. To reach temperatures below 30 mK and to allow for the use of an internal polarization magnet, the polarized target group is building a new continuous mode dilution refrigerator. As a optimizing tool for the construction of dilution refrigerators and for a better understanding of the different incoming and outgoing fluid streams several CFD-simulations are done. First the different streams are simulated independently for different parts of the refrigerator to get a better estimation of the flow parameters. Then the simulation is extended to include the heat exchange between the different streams at the heat exchangers for different operational parameters of the refrigerator. Afterwards the precooling stages of the refrigerator will be tested to compare the predicted and the measured operational parameters.

  15. Dynamic Heat Transfer Model of Refrigerated Foodstuff

    DEFF Research Database (Denmark)

    Cai, Junping; Risum, Jørgen; Thybo, Claus

    2006-01-01

    happens to the food inside during this period, when we look at the quality factor? This paper discusses quality model of foodstuff, different scenarios of defrost scheme are simulated, questions such as how the defrost temperature and duration influence the food temperature, thus the food quality, as well...

  16. Performance of an auto refrigerant cascade refrigerator operating in gas refrigerant supply (GRS) mode with nitrogen-hydrocarbon and argon-hydrocarbon refrigerants

    Science.gov (United States)

    Gurudath Nayak, H.; Venkatarathnam, G.

    2009-07-01

    There is a worldwide interest in the development of auto refrigerant cascade (ARC) refrigerators operating with refrigerant mixtures. Both flammable and non-flammable refrigerant mixtures can be used in these systems. The performance of an ARC system with optimum nitrogen-hydrocarbon and argon-hydrocarbon mixtures between 90 and 160 K is presented in this paper.

  17. A feasibility analysis of replacing the standard ammonia refrigeration device with the cascade NH3/CO2 refrigeration device in the food industry

    Directory of Open Access Journals (Sweden)

    Jankovich Dennis

    2015-01-01

    Full Text Available The thermodynamic analysis demonstrates the feasibility of replacing the standard ammonia refrigeration device with the cascade NH3/CO2 refrigeration device in the food industry. The main reason for replacement is to reduce the total amount of ammonia in spaces like deep-freezing chambers, daily chambers, working rooms and technical passageways. An ammonia-contaminated area is hazardous to human health and the safety of food products. Therefore the preferred reduced amount of ammonia is accumulated in the Central Refrigeration Engine Room, where the cascade NH3/CO2 device is installed as well. Furthermore, the analysis discusses and compares two left Carnot¢s refrigeration cycles, one for the standard ammonia device and the other for the cascade NH3/CO2 device. Both cycles are processes with two-stage compression and two-stage throttling. The thermodynamic analysis demonstrates that the selected refrigeration cycle is the most cost-effective process because it provides the best numerical values for the total refrigeration factor with respect to the observed refrigeration cycle. The chief analyzed influential parameters of the cascade device are: total refrigeration load, total reactive power, mean temperature of the heat exchanger, evaporating and condensing temperature of the low-temperature part.

  18. Cryogen-free dilution refrigerator for bolometric search of ...

    Indian Academy of Sciences (India)

    of a still, a 50 mK cold plate, a MC and a series of heat exchangers, integrated with a ... flow rate of ∼1900 μmol/s beyond which the system becomes unstable). .... refrigerator with an intrinsic heat leak, ˙Q0 present in the system, ... of 1.4 mW at 120 mK, has been successfully installed and tested at TIFR, Mumbai, India.

  19. Numerical analysis of an air condenser working with the refrigerant fluid R407C

    International Nuclear Information System (INIS)

    Aprea, Ciro; Maiorino, Angelo

    2007-01-01

    As CFC (clorofluorocarbon) and HCFC (hydrochlorofluorocarbon) refrigerants which have been used as refrigerants in a vapour compression refrigeration system were know to provide a principal cause to ozone depletion and global warming, production and use of these refrigerants have been restricted. Therefore, new alternative refrigerants should be searched for, which fit to the requirements in an air conditioner or a heat pump, and refrigerant mixtures which are composed of HFC (hydrofluorocarbon) refrigerants having zero ODP (ozone depletion potential) are now being suggested as drop-in or mid-term replacement. However also these refrigerants, as the CFC and HCFC refrigerants, present a greenhouse effect. The zeotropic mixture designated as R407C (R32/R125/R134a 23/25/52% in mass) represents a substitute of the HCFC22 for high evaporation temperature applications as the air-conditioning. Aim of the paper is a numerical-experimental analysis for an air condenser working with the non azeotropic mixture R407C in steady-state conditions. A homogeneous model for the condensing refrigerant is considered to forecast the performances of the condenser; this model is capable of predicting the distributions of the refrigerant temperature, the velocity, the void fraction, the tube wall temperature and the air temperature along the test condenser. Obviously in the refrigerant de-superheating phase the numerical analysis becomes very simple. A comparison with the measurements on an air condenser mounted in an air channel linked to a vapour compression plant is discussed. The results show that the simplified model provides a reasonable estimation of the steady-state response and that this model is useful to design purposes

  20. Substitution of R502 in existing refrigerating, air-conditioning and heat pump systems with refrigerants of low ozone depletion potential in the Federal Republic of Germany; Ersatz von R 502 in bestehenden Kaelte-, Klima- und Waermepumpenanlagen in der Bundesrepublik Deutschland durch Kaeltemittel mit geringerem Ozonabbaupotential

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-06-01

    The technical basics and the state of engineering for the substitution of R502 in existing refrigeration systems are described and explained. The report contains an overview of the current applications of R502 in the FRG, the presentation and discussion of existing substitutes, the presentation and valuations of research and experiences with the adaptation to alternative refrigerants, the presentation of the required infrastructure and a discussion of the technical feasibility. The conversion of existing systems to refrigerants of lower ozone depletion potential is in conclusion valuated with regard to its technical feasibility, environmental relevance and economic efficiency. (orig.) [Deutsch] Es werden die technischen Grundlagen und der Stand der Technik zum Ersatz von R502 in bestehenden Kaelteanlagen dargestellt und erlaeutert. Der Bericht beinhaltet einen Ueberblick ueber die derzeitige Anwendung von R502 in der BRD, die Vorstellung und Diskussion existierender Ersatzstoffe, die Darstellung und Bewertung der Forschung und Erfahrungen zu Umruestungen auf Ersatzstoffe, die Vorstellung der erforderlichen Infrastruktur und die Diskussion der technischen Durchfuehrbarkeit. Die Umstellung bestehender Anlagen auf Kaeltemittel mit geringerem Ozonabbaupotential wird abschliessend hinsichtlich der technischen Durchfuehrbarkeit, der Umweltrelevanz und der Wirtschaftlichkeit bewertet. (orig.)

  1. Dynamic analysis of the CTAR (constant temperature adsorption refrigeration) cycle

    International Nuclear Information System (INIS)

    Hassan, H.Z.; Mohamad, A.A.; Al-Ansary, H.A.; Alyousef, Y.M.

    2014-01-01

    The basic SAR (solar-driven adsorption refrigeration) machine is an intermittent cold production system. Recently, the CO-SAR (continuous operation solar-powered adsorption refrigeration) system is developed. The CO-SAR machine is based on the theoretical CTAR (constant temperature adsorption refrigeration) cycle in which the adsorption process takes place at a constant temperature that equals the ambient temperature. Practically, there should be a temperature gradient between the adsorption bed and the surrounding atmosphere to provide a driving potential for heat transfer. In the present study, the dynamic analysis of the CTAR cycle is developed. This analysis provides a comparison between the theoretical and the dynamic operation of the CTAR cycle. The developed dynamic model is based on the D-A adsorption equilibrium equation and the energy and mass balances in the adsorption reactor. Results obtained from the present work demonstrate that, the idealization of the constant temperature adsorption process in the theoretical CTAR cycle is not far from the real situation and can be approached. Furthermore, enhancing the heat transfer between the adsorption bed and the ambient during the bed pre-cooling process helps accelerating the heat rejection process from the adsorption reactor and therefore approaching the isothermal process. - Highlights: • The dynamic analysis of the CTAR (constant temperature adsorption refrigeration) cycle is developed. • The CTAR theoretical and dynamic cycles are compared. • The dynamic cycle approaches the ideal one by enhancing the bed precooling

  2. Validation of satellite-derived tropical cyclone heat potential with in situ observations in the North Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Nagamani, P.V.; Ali, M.M.; Goni, G.J.; Dinezio, P.N.; Pezzullo, J.C.; UdayaBhaskar, T.V.S.; Gopalakrishna, V.V.; Nisha, K.

    validation with in situ estimations for quantification of their reliability and consistency. Once the validation has been carried out, the satellite-derived TCHP values with their improved tempo- ral and spatial properties can be conveniently used...

  3. Optimal design of gas adsorption refrigerators for cryogenic cooling

    Science.gov (United States)

    Chan, C. K.

    1983-01-01

    The design of gas adsorption refrigerators used for cryogenic cooling in the temperature range of 4K to 120K was examined. The functional relationships among the power requirement for the refrigerator, the system mass, the cycle time and the operating conditions were derived. It was found that the precool temperature, the temperature dependent heat capacities and thermal conductivities, and pressure and temperature variations in the compressors have important impacts on the cooling performance. Optimal designs based on a minimum power criterion were performed for four different gas adsorption refrigerators and a multistage system. It is concluded that the estimates of the power required and the system mass are within manageable limits in various spacecraft environments.

  4. Limited options for low-global-warming-potential refrigerants

    Science.gov (United States)

    McLinden, Mark O.; Brown, J. Steven; Brignoli, Riccardo; Kazakov, Andrei F.; Domanski, Piotr A.

    2017-02-01

    Hydrofluorocarbons, currently used as refrigerants in air-conditioning systems, are potent greenhouse gases, and their contribution to climate change is projected to increase. Future use of the hydrofluorocarbons will be phased down and, thus replacement fluids must be found. Here we show that only a few pure fluids possess the combination of chemical, environmental, thermodynamic, and safety properties necessary for a refrigerant and that these fluids are at least slightly flammable. We search for replacements by applying screening criteria to a comprehensive chemical database. For the fluids passing the thermodynamic and environmental screens (critical temperature and global warming potential), we simulate performance in small air-conditioning systems, including optimization of the heat exchangers. We show that the efficiency-versus-capacity trade-off that exists in an ideal analysis disappears when a more realistic system is considered. The maximum efficiency occurs at a relatively high volumetric refrigeration capacity, but there are few fluids in this range.

  5. ENERGY STAR Certified Residential Refrigerators

    Data.gov (United States)

    U.S. Environmental Protection Agency — Certified models meet all ENERGY STAR requirements as listed in the Version 5.0 ENERGY STAR Program Requirements for Residential Refrigerators and Freezers that are...

  6. Performance of refrigerating machineries with new refrigerants; Performance des machines frigorifiques avec les nouveaux refrigerants

    Energy Technology Data Exchange (ETDEWEB)

    Bailly, A; Jurkowski, R [CIAT, 01 - Culoz (France)

    1998-12-31

    This paper reports on a comparative study of the thermal performances of different refrigerants like R-22, R-134a, R-404A and R-407C when used as possible substitutes for the HCFC22 refrigerant in a given refrigerating machinery equipped with compact high performance plate exchangers. Thermal performances are compared in identical operating conditions. The behaviour of the two-phase exchange coefficient is analyzed with respect to the different parameters. The composition of the mixture after one year of operation has been analyzed too and the influence of oil on the performances is studied. (J.S.)

  7. Performance of refrigerating machineries with new refrigerants; Performance des machines frigorifiques avec les nouveaux refrigerants

    Energy Technology Data Exchange (ETDEWEB)

    Bailly, A.; Jurkowski, R. [CIAT, 01 - Culoz (France)

    1997-12-31

    This paper reports on a comparative study of the thermal performances of different refrigerants like R-22, R-134a, R-404A and R-407C when used as possible substitutes for the HCFC22 refrigerant in a given refrigerating machinery equipped with compact high performance plate exchangers. Thermal performances are compared in identical operating conditions. The behaviour of the two-phase exchange coefficient is analyzed with respect to the different parameters. The composition of the mixture after one year of operation has been analyzed too and the influence of oil on the performances is studied. (J.S.)

  8. Effects of hysteresis and Brayton cycle constraints on magnetocaloric refrigerant performance

    Science.gov (United States)

    Brown, T. D.; Buffington, T.; Shamberger, P. J.

    2018-05-01

    Despite promising proofs of concept, system-level implementation of magnetic refrigeration has been critically limited by history-dependent refrigerant losses that interact with governing thermodynamic cycles to adversely impact refrigeration performance. Future development demands a more detailed understanding of how hysteresis limits performance, and of how different types of cycles can mitigate these limitations, but without the extreme cost of experimental realization. Here, the utility of Brayton cycles for magnetic refrigeration is investigated via direct simulation, using a combined thermodynamic-hysteresis modeling framework to compute the path-dependent magnetization and entropy of a model alloy for a variety of feasible Brayton cycles between 0-1.5 T and 0-5 T. By simultaneously varying the model alloy's hysteresis properties and applying extensions of the thermodynamic laws to non-equilibrium systems, heat transfers and efficiencies are quantified throughout the space of hystereses and Brayton cycles and then compared with a previous investigation using Ericsson cycles. It is found that (1) hysteresis losses remain a critical obstacle to magnetic refrigeration implementation, with efficiencies >80% in the model system requiring hysteresis refrigerant transformation temperatures at the relevant fields; (3) for a given hysteresis and field constraint, Brayton and Ericsson-type cycles generate similar efficiencies; for a given temperature span, Ericsson cycles lift more heat per cycle, with the difference decreasing with the refrigerant heat capacity outside the phase transformation region.

  9. Refrigeration plants for the SSCL

    International Nuclear Information System (INIS)

    McAshan, M.; Ganni, V.; Than, R.; Niehaus, T.

    1991-03-01

    The basic requirements and operating features of the collider cryogenic system have already been described in other publications. The general arrangement of the refrigeration plant and its subsystems is presented, and the issue of how to provide redundancy in the cryogenic system is addressed, and some of the basic features of the refrigeration plants are described. The collider cryogenic system design is not final yet, and this report only reflects the direction and current status of the cryogenic system design

  10. General review of solar-powered closed sorption refrigeration systems

    International Nuclear Information System (INIS)

    Sarbu, Ioan; Sebarchievici, Calin

    2015-01-01

    Highlights: • Provide review of development in solar sorption refrigeration technologies. • Theoretical basis and applications of absorption and adsorption cycles are discussed. • Thermodynamic properties of most common working pairs have been reviewed. • Development of hybrid or thermal energy storage adsorption systems was explored. • A comparison between solar-powered absorption and adsorption systems was performed. - Abstract: The negative environmental impacts of burning fossil fuels have forced the energy research community seriously to consider renewable sources, such as naturally available solar energy. Thermally powered refrigeration technologies are classified into two categories: thermo-mechanical technology and sorption technology (open systems or closed systems). This paper provides a detailed review of the solar closed sorption (absorption and adsorption) refrigeration systems, which utilise working pairs (fluids). After an introduction of the basic principles of these systems, the history of development and recent advances in solar sorption refrigeration technologies are reported. The adsorption cooling typically has a lower heat source temperature requirement than the absorption cooling. Based on the coefficient of performance (COP), the absorption systems are preferred over the adsorption systems, and the higher temperature issues can be easily handled with solar adsorption systems. The thermodynamic properties of most common working fluids, as well as the use of ternary mixtures in solar-powered absorption systems, have been reviewed in this study. The paper also refers to new approaches to increase the efficiency and sustainability of the basic adsorption cycles, such as the development of hybrid or thermal energy storage adsorption systems. This research shows that solar-powered closed sorption refrigeration technologies can be attractive alternatives not only to serve the needs for air-conditioning, refrigeration, ice making, thermal

  11. Heat Pump Efficiencies simulated in Aspen HYSYS and Aspen Plus

    OpenAIRE

    Øi, Lars Erik; Tirados, Irene Yuste

    2015-01-01

    Heat pump technology provides an efficient and sustainable solution for both heating and cooling. A traditional heat pump can be defined as a mechanical-compression cycle refrigeration system powered by electricity. Traditional refrigerants used in heat pumps are ammonia or chlorinated and fluorinated hydrocarbons. Because many of these chlorofluorohydrocarbons (CFC??) are ozone-depleting components, evaluation of more environmentally friendly refrigerants like pure hydrocarbons is important....

  12. Experimental study of refrigeration performance based on linear Fresnel solar thermal photovoltaic system

    Science.gov (United States)

    Song, Jinghui; Yuan, Hui; Xia, Yunfeng; Kan, Weimin; Deng, Xiaowen; Liu, Shi; Liang, Wanlong; Deng, Jianhua

    2018-03-01

    This paper introduces the working principle and system constitution of the linear Fresnel solar lithium bromide absorption refrigeration cycle, and elaborates several typical structures of absorption refrigeration cycle, including single-effect, two-stage cycle and double-effect lithium bromide absorption refrigeration cycle A 1.n effect absorption chiller system based on the best parameters was introduced and applied to a linear Fresnel solar absorption chiller system. Through the field refrigerator performance test, the results show: Based on this heat cycle design and processing 1.n lithium bromide absorption refrigeration power up to 35.2KW, It can meet the theoretical expectations and has good flexibility and reliability, provides guidance for the use of solar thermal energy.

  13. 2017 German refrigeration and air conditioning meeting. Proceedings

    International Nuclear Information System (INIS)

    2017-01-01

    This year's lecture programme includes 117 presentations in the five working departments of DKV and 10 lectures at the special event ''Energy-efficient air conditioning in data centres''. The main topics in the respective departments were: (1) Cryogenics: Space applications; Cryogenic plants; Cryomedicine and cryobiology; Components, developments; Processes and plants; Valves, design. (2) Basics: Evaporation, material values; evaporation, condensation; absorption; adsorption, latent storage; cycle simulation. (3) Components: CO 2 plant engineering and components; refrigerants; process control, adsorption, sublimation and storage technology; refrigerating machine oils, heat exchangers and corrosion; components 4.0, sensors and control technology; simulation of plant processes. (4) Cold application: Application; Application / Natural Refrigerants; Mobile Applications Car; Mobile Applications; Supermarket / Efficiency; Optimization / Efficiency. (5) Air conditioning and heat pump applications: load shifting, smart home, flexibility; heat sources and industrial heat pumps; modelling, simulations; energy concepts heat pumps and photovoltaics; monitoring, evaluation; technology trends / working materials. Six papers are separately analyzed for this database. [de

  14. Salt pill design and fabrication for adiabatic demagnetization refrigerators

    Science.gov (United States)

    Shirron, Peter J.; McCammon, Dan

    2014-07-01

    The performance of an adiabatic demagnetization refrigerator (ADR) is critically dependent on the design and construction of the salt pills that produce cooling. In most cases, the primary goal is to obtain the largest cooling capacity at the low temperature end of the operating range. The realizable cooling capacity depends on a number of factors, including refrigerant mass, and how efficiently it absorbs heat from the various instrument loads. The design and optimization of “salt pills” for ADR systems depend not only on the mechanical, chemical and thermal properties of the refrigerant, but also on the range of heat fluxes that the salt pill must accommodate. Despite the fairly wide variety of refrigerants available, those used at very low temperature tend to be hydrated salts that require a dedicated thermal bus and must be hermetically sealed, while those used at higher temperature - greater than about 0.5 K - tend to be single- or poly-crystals that have much simpler requirements for thermal and mechanical packaging. This paper presents a summary of strategies and techniques for designing, optimizing and fabricating salt pills for both low- and mid-temperature applications.

  15. Salt Pill Design and Fabrication for Adiabatic Demagnetization Refrigerators

    Science.gov (United States)

    Shirron, Peter J.; Mccammon, Dan

    2014-01-01

    The performance of an adiabatic demagnetization refrigerator (ADR) is critically dependent on the design and construction of the salt pills that produce cooling. In most cases, the primary goal is to obtain the largest cooling capacity at the low temperature end of the operating range. The realizable cooling capacity depends on a number of factors, including refrigerant mass, and how efficiently it absorbs heat from the various instrument loads. The design and optimization of "salt pills" for ADR systems depend not only on the mechanical, chemical and thermal properties of the refrigerant, but also on the range of heat fluxes that the salt pill must accommodate. Despite the fairly wide variety of refrigerants available, those used at very low temperature tend to be hydrated salts that require a dedicated thermal bus and must be hermetically sealed, while those used at higher temperature - greater than about 0.5 K - tend to be single-­- or poly-­-crystals that have much simpler requirements for thermal and mechanical packaging. This paper presents a summary of strategies and techniques for designing, optimizing and fabricating salt pills for both low-­- and mid-­-temperature applications.

  16. Cooling load and coefficient of performance optimizations for real air-refrigerators

    International Nuclear Information System (INIS)

    Tu Youming; Chen Lingen; Sun Fengrui; Wu Chih

    2006-01-01

    Based on a simple irreversible variable-temperature heat reservoir air (Brayton) refrigeration cycle model, a performance analysis and optimization of a real air refrigerator is carried out using finite-time thermodynamics. To maximize the cooling load and the coefficient of performance (COP) of the cycle, the allocation of a fixed total heat-exchanger inventory and thermal-capacity rate matching between the working fluid and heat reservoirs are optimized, respectively. The influences of pressure ratio, the total heat-exchanger inventory, the efficiencies of the compressor and expander, the thermal capacity rate of the working fluid and the ratio of the thermal-capacity rates of the heat reservoirs on the performance of the cycle are shown by numerical examples. The results obtained provide guidances for the design of practical air-refrigeration plants

  17. Evaluation of Refrigerating and Air Conditioning Devices in Energy Cascade Systems under the Restriction of Carbon Dioxide Emissions

    Science.gov (United States)

    Shimazaki, Yoichi; Akisawa, Atsushi; Kashiwagi, Takao

    It is necessary to introduce energy cascade systems into the industrial sector in Japan to reduce carbon dioxide emissions. The aim of this study is to evaluate the refrigerating and air conditioning devices in cases of introducing both energy cascade systems and thermal recycling systems in industries located around urban areas. The authors have developed an energy cascade model based on linear programming so as to minimize the total system costs with carbon taxes. Five cases are investigated. Limitation of carbon dioxide emissions results in the enhancement of heat cascading, where high temperature heat is supplied for process heating while low temperature one is shifted to refrigeration. It was found that increasing the amount of garbage combustor waste heat can reduce electric power for the turbo refrigerator by promoting waste heat driven ammonia absorption refrigerator.

  18. Simulation of shell-and-tube condensers of the refrigerating machines with superheated and subcooled refrigerant

    International Nuclear Information System (INIS)

    Ciconkov, Risto

    1994-01-01

    Opposite to many authors who found the simulation of the shell-and-tube condensers on the condensing process only, in this work all thermodynamic processes which appear such as: the process of cooling the superheated refrigerant to the saturated vapor, the process of condensation and option with subcooling are considered. A selection of heat transfer equations is made corresponding to the processes, a mathematical model and adequate computer programme are composed. The functioning of this programme is presented on a concrete example. A computer programing knowledge for the using programme is not necessary. Neither is a programme support. (author)

  19. Design and dynamic behaviour of a cold storage system combined with a solar powered thermoacoustic refrigerator

    International Nuclear Information System (INIS)

    Perier-Muzet, Maxime; Bedecarrats, Jean-Pierre; Stouffs, Pascal; Castaing-Lasvignottes, Jean

    2014-01-01

    A heat powered thermoacoustic refrigerator consists in a thermoacoustic engine that produces acoustic work utilizing heat, coupled to a thermoacoustic cooler that converts this acoustic energy into cooling effect. These machines have already proved their capability in laboratory or in space refrigeration. Previous studies have also demonstrated the possibility of using concentrated solar energy as thermal energy sources for low power heat driven thermoacoustic refrigerators. As other solar refrigeration systems, even if the cooling demand generally increases with the intensity of the solar radiation, one of the major difficulties is to insure a frigorific power supply when there is no, or low, solar radiation. The aim of this work is to study a kW scale solar thermoacoustic refrigerator capable to reach temperatures of the industrial refrigeration domain. This refrigerator is combined with a latent cold storage in order to guarantee a sufficient cooling capacity to face to refrigeration loads in spite of the production fluctuations. A description of the studied prototype is done and the model developed to describe the transient behaviour of the main components of this machine is introduced. The results obtained with a simulation of one week with real solar radiations are presented and the behaviour and the energetic performances of the entire system are analysed. Finally the impact of the sizing of the cold storage system is discussed. With the best storage design, the system is capable to supply a cooling power of 400 W at a temperature equal or lower than −20 °C with an average Coefficient Of Performance of the solar thermoacoustic refrigerator equal to 21%

  20. Development of satellite green vegetation fraction time series for use in mesoscale modeling: application to the European heat wave 2006

    DEFF Research Database (Denmark)

    Nielsen, Joakim Refslund; Dellwik, Ebba; Hahmann, Andrea N.

    2014-01-01

    A method is presented for development of satellite green vegetation fraction (GVF) time series for use in the Weather Research and Forecasting (WRF) model. The GVF data is in the WRF model used to describe the temporal evolution of many land surface parameters, in addition to the evolution of veg...

  1. Optimal heat rejection pressure in transcritical carbon dioxide air conditioning and heat pump systems

    DEFF Research Database (Denmark)

    Liao, Shengming; Jakobsen, Arne

    1998-01-01

    Due to the urgent need for environmentally benign refrigerants, the use of the natural substance carbon dioxide in refrigeration systems has gained more and more attention. In systems such as automobile air-conditioners and heat pumps, owing to the relatively high heat rejection temperatures, the...... dioxide air conditioning or heat pump systems and for intelligent controlling such systems.......Due to the urgent need for environmentally benign refrigerants, the use of the natural substance carbon dioxide in refrigeration systems has gained more and more attention. In systems such as automobile air-conditioners and heat pumps, owing to the relatively high heat rejection temperatures......, the cycles using carbon dioxide as refrigerant will have to operate in the transcritical area. In a transcritical carbon dioxide system, there is an optimal heat rejection pressure that gives a maximum COP. In this paper, it is shown that the value of this optimal heat rejection pressure mainly depends...

  2. CFD-simulations of a 4π-continuous-mode dilution refrigerator for the CB-ELSA experiment

    Energy Technology Data Exchange (ETDEWEB)

    Bornstein, Marcel; Dutz, Hartmut; Goertz, Stefan; Reeve, Scott; Runkel, Stefan [Physikalisches Institut, Bonn Univ. (Germany); Collaboration: CBELSA/TAPS-Collaboration

    2016-07-01

    The polarized target group at Bonn operates a dilution refrigerator for double polarization experiments at the Crystal Barrel in Bonn. To get high target polarizations and long relaxation times low temperatures are indispensable. To reach temperatures below 30 mK and to allow for the use of an internal polarization magnet, the polarized target group is building a new continuous mode dilution refrigerator. As a optimizing tool for the construction of dilution refrigerators and for a better understanding of the different incoming and outgoing fluid streams several Computational Fluid Dynamic simulations are done. The heat exchange between the different streams of the refrigerator were simulated for the precooling stages within one simulation including a submesh for each fluid and solid. This leads to a better estimation of the flow characteristics and the operational parameter of the refrigerator. The last steps of construction and the preparation of the refrigerator for first test measurements are ongoing.

  3. Mapping urban heat islands of arctic cities using combined data on field measurements and satellite images based on the example of the city of Apatity (Murmansk Oblast)

    Science.gov (United States)

    Konstantinov, P. I.; Grishchenko, M. Y.; Varentsov, M. I.

    2015-12-01

    This article presents the results of a study of the urban heat island (UHI) in the city of Apatity during winter that were obtained according to the data of field meteorological measurements and satellite images. Calculations of the surface layer temperature have been made based on the surface temperature data obtained from satellite images. The experimental data on air temperature were obtained as a result of expeditionary meteorological observations, and the experimental data on surface temperature were obtained based on the data of the space hyperspectral Moderate-Resolution Imaging Spectroradiometer (MODIS) system, channels 31 and 32 (10.78-11.28 and 11.77-12.27 micrometers, respectively). As a result of the analysis of temperature fields, an intensive heat island (up to 3.2°C) has been identified that was estimated based on the underlying surface temperature, and its mean intensity over the observation period significantly exceeds the representative data for European cities in winter. It has also been established that the air temperature calculated according to the MODIS data is systematically higher under winter conditions than the air temperature from direct measurement data.

  4. Experimental investigation of integrated refrigeration system (IRS) with gas engine, compression chiller and absorption chiller

    International Nuclear Information System (INIS)

    Sun, Z.G.

    2008-01-01

    An integrated refrigeration system (IRS) with a gas engine, a vapor-compression chiller and an absorption chiller is set up and tested. The vapor-compression refrigeration cycle is operated directly by the gas engine. The waste heat from the gas engine operates the absorption refrigeration cycle, which provides additional cooling. The performance of the IRS is described. The cooling capacity of the IRS is about 596 kW, and primary energy ratio (PER) reaches 1.84 at air-conditioning rated conditions. The refrigerating capacity of the prototype increased and PER of prototype decreased with the increase of the gas engine speed. The gas engine speed was preferably regulated at part load condition in order to operate the prototype at high-energy efficiency. The refrigerating capacity and PER of the prototype increased with the increase of the outlet temperature of chilled water or the decrease of the inlet temperature of cooling water. The integrated refrigeration chiller in this work saves running costs as compared to the conventional refrigeration system by using the waste heat

  5. Computational Model of a Biomass Driven Absorption Refrigeration System

    Directory of Open Access Journals (Sweden)

    Munyeowaji Mbikan

    2017-02-01

    Full Text Available The impact of vapour compression refrigeration is the main push for scientists to find an alternative sustainable technology. Vapour absorption is an ideal technology which makes use of waste heat or renewable heat, such as biomass, to drive absorption chillers from medium to large applications. In this paper, the aim was to investigate the feasibility of a biomass driven aqua-ammonia absorption system. An estimation of the solid biomass fuel quantity required to provide heat for the operation of a vapour absorption refrigeration cycle (VARC is presented; the quantity of biomass required depends on the fuel density and the efficiency of the combustion and heat transfer systems. A single-stage aqua-ammonia refrigeration system analysis routine was developed to evaluate the system performance and ascertain the rate of energy transfer required to operate the system, and hence, the biomass quantity needed. In conclusion, this study demonstrated the results of the performance of a computational model of an aqua-ammonia system under a range of parameters. The model showed good agreement with published experimental data.

  6. Study on the CFD simulation of refrigerated container

    Science.gov (United States)

    Arif Budiyanto, Muhammad; Shinoda, Takeshi; Nasruddin

    2017-10-01

    The objective this study is to performed Computational Fluid Dynamic (CFD) simulation of refrigerated container in the container port. Refrigerated container is a thermal cargo container constructed from an insulation wall to carry kind of perishable goods. CFD simulation was carried out use cross sectional of container walls to predict surface temperatures of refrigerated container and to estimate its cooling load. The simulation model is based on the solution of the partial differential equations governing the fluid flow and heat transfer processes. The physical model of heat-transfer processes considered in this simulation are consist of solar radiation from the sun, heat conduction on the container walls, heat convection on the container surfaces and thermal radiation among the solid surfaces. The validation of simulation model was assessed uses surface temperatures at center points on each container walls obtained from the measurement experimentation in the previous study. The results shows the surface temperatures of simulation model has good agreement with the measurement data on all container walls.

  7. Theoretical Models for the Cooling Power and Base Temperature of Dilution Refrigerators

    CERN Document Server

    Wikus, Patrick

    2010-01-01

    He-3/He-4 dilution refrigerators are widely used for applications requiring continuous cooling at temperatures below approximately 300 mK. Despite of the popularity of these devices in low temperature physics, the thermodynamic relations underlying the cooling mechanism of He-3/He-4 refrigerators are very often incorrectly used. Several thermodynamic models of dilution refrigeration have been published in the past, sometimes contradicting each other. These models are reviewed and compared with each other over a range of different He-3 flow rates. In addition, a new numerical method for the calculation of a dilution refrigerator's cooling power at arbitrary flow rates is presented. This method has been developed at CERN's Central Cryogenic Laboratory. It can be extended to include many effects that cannot easily be accounted for by any of the other models, including the degradation of heat exchanger performance due to the limited number of step heat exchanger elements, which can be considerable for some design...

  8. Development and Evaluation of a Sandia Cooler-based Refrigerator Condenser

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Terry A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Kariya, Harumichi Arthur [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Leick, Michael T. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Zimmerman, Mark D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Li, Manjie [Univ. of Maryland, College Park, MD (United States); Du, Yilin [Univ. of Maryland, College Park, MD (United States); Lee, Hoseong [Univ. of Maryland, College Park, MD (United States); Hwang, Yunho [Univ. of Maryland, College Park, MD (United States); Radermacher, Reinhard [Univ. of Maryland, College Park, MD (United States)

    2015-07-01

    This report describes the first design of a refrigerator condenser using the Sandia Cooler, i.e. air - bearing supported rotating heat - sink impeller. The project included ba seline performance testing of a residential refrigerator, analysis and design development of a Sandia Cooler condenser assembly including a spiral channel baseplate, and performance measurement and validation of this condenser system as incorporated into the residential refrigerator. Comparable performance was achieved in a 60% smaller volume package. The improved modeling parameters can now be used to guide more optimized designs and more accurately predict performance.

  9. Triple-effect absorption refrigeration system with double-condenser coupling

    Science.gov (United States)

    DeVault, Robert C.; Biermann, Wendell J.

    1993-01-01

    A triple effect absorption refrigeration system is provided with a double-condenser coupling and a parallel or series circuit for feeding the refrigerant-containing absorbent solution through the high, medium, and low temperature generators utilized in the triple-effect system. The high temperature condenser receiving vaporous refrigerant from the high temperature generator is double coupled to both the medium temperature generator and the low temperature generator to enhance the internal recovery of heat within the system and thereby increase the thermal efficiency thereof.

  10. Modelling and control of large cryogenic refrigerator

    International Nuclear Information System (INIS)

    Bonne, Francois

    2014-01-01

    This manuscript is concern with both the modeling and the derivation of control schemes for large cryogenic refrigerators. The particular case of those which are submitted to highly variable pulsed heat load is studied. A model of each object that normally compose a large cryo-refrigerator is proposed. The methodology to gather objects model into the model of a subsystem is presented. The manuscript also shows how to obtain a linear equivalent model of the subsystem. Based on the derived models, advances control scheme are proposed. Precisely, a linear quadratic controller for warm compression station working with both two and three pressures state is derived, and a predictive constrained one for the cold-box is obtained. The particularity of those control schemes is that they fit the computing and data storage capabilities of Programmable Logic Controllers (PLC) with are well used in industry. The open loop model prediction capability is assessed using experimental data. Developed control schemes are validated in simulation and experimentally on the 400W1.8K SBT's cryogenic test facility and on the CERN's LHC warm compression station. (author) [fr

  11. Qubit absorption refrigerator at strong coupling

    Science.gov (United States)

    Mu, Anqi; Agarwalla, Bijay Kumar; Schaller, Gernot; Segal, Dvira

    2017-12-01

    We demonstrate that a quantum absorption refrigerator (QAR) can be realized from the smallest quantum system, a qubit, by coupling it in a non-additive (strong) manner to three heat baths. This function is un-attainable for the qubit model under the weak system-bath coupling limit, when the dissipation is additive. In an optimal design, the reservoirs are engineered and characterized by a single frequency component. We then obtain closed expressions for the cooling window and refrigeration efficiency, as well as bounds for the maximal cooling efficiency and the efficiency at maximal power. Our results agree with macroscopic designs and with three-level models for QARs, which are based on the weak system-bath coupling assumption. Beyond the optimal limit, we show with analytical calculations and numerical simulations that the cooling efficiency varies in a non-universal manner with model parameters. Our work demonstrates that strongly-coupled quantum machines can exhibit function that is un-attainable under the weak system-bath coupling assumption.

  12. Design of an ejector cycle refrigeration system

    International Nuclear Information System (INIS)

    Grazzini, G.; Milazzo, A.; Paganini, D.

    2012-01-01

    Highlights: ► A design procedure is presented for an ejection refrigeration system. ► Properties of applicable operating fluids are presented and R245fa is selected. ► Real gas properties are used. ► The diffuser is designed with a profile that controls momentum change. ► Fluid friction is accounted for along all main components. - Abstract: A design procedure, based on a one-dimensional simulation, is presented for an ejection refrigeration system. Heat exchangers are included in the calculation, accounting for temperature differences between the fluids and for pressure losses. The ideal gas assumption, which is quite common in the literature concerning ejector systems, is avoided. Furthermore, the supersonic diffuser is designed with a continuous profile, without cylindrical piece, controlling the variation of momentum along the flow path and accounting for friction. At design conditions, this should reduce the irreversibility due to the normal shock. A comparison between different operating fluids is presented and R245fa is selected. The results of the design procedure and the expected performance, in terms of first and second law efficiency, are presented.

  13. Optimal thermoeconomic performance of an irreversible regenerative ferromagnetic Ericsson refrigeration cycle

    International Nuclear Information System (INIS)

    Xu, Zhichao; Guo, Juncheng; Lin, Guoxing; Chen, Jincan

    2016-01-01

    On the basis of the Langevin theory of classical statistical mechanics, the magnetization, entropy, and iso-field heat capacity of ferromagnetic materials are analyzed and their mathematical expressions are derived. An irreversible regenerative Ericsson refrigeration cycle by using a ferromagnetic material as the working substance is established, in which finite heat capacity rates of low and high temperature reservoirs, non-perfect regenerative heat of the refrigeration cycle, additional regenerative heat loss, etc. are taken into account. Based on the regenerative refrigeration cycle model, a thermoeconomic function is introduced as one objective function and optimized with respect to the temperatures of the working substance in the two iso-thermal processes. By means of numerical calculation, the effects of the effective factor of the heat exchangers in high/low temperature reservoir sides, efficiency of the regenerator, heat capacity rate of the low temperature reservoir, and applied magnetic field on the optimal thermoeconomic function as well as the corresponding cooling rate and coefficient of performance are revealed. The results obtained in this paper can provide some theoretical guidance for the optimal design of actual regenerative magnetic refrigerator cycle. - Highlights: • Thermodynamic performance of ferromagnetic material is analyzed. • An irreversible regenerative ferromagnetic Ericsson refrigeration cycle is set up. • The thermoeconomic objective function is introduced and optimized. • Impacts of the thermoeconomic and other parameters are discussed.

  14. Performance analysis of a large-scale helium Brayton cryo-refrigerator with static gas bearing turboexpander

    International Nuclear Information System (INIS)

    Zhang, Yu; Li, Qiang; Wu, Jihao; Li, Qing; Lu, Wenhai; Xiong, Lianyou; Liu, Liqiang; Xu, Xiangdong; Sun, Lijia; Sun, Yu; Xie, Xiujuan; Wang, Bingming; Qiu, Yinan; Zhang, Peng

    2015-01-01

    Highlights: • A 2 kW at 20.0 K helium Brayton cryo-refrigerator is built in China. • A series of tests have been systematically conducted to investigate the performance of the cryo-refrigerator. • Maximum heat conductance proportion (90.7%) appears in the heat exchangers of cold box rather than those of heat reservoirs. • A model of helium Brayton cryo-refrigerator/cycle is presented according to finite-time thermodynamics. - Abstract: Large-scale helium cryo-refrigerator is widely used in superconducting systems, nuclear fusion engineering, and scientific researches, etc., however, its energy efficiency is quite low. First, a 2 kW at 20.0 K helium Brayton cryo-refrigerator is built, and a series of tests have been systematically conducted to investigate the performance of the cryo-refrigerator. It is found that maximum heat conductance proportion (90.7%) appears in the heat exchangers of cold box rather than those of heat reservoirs, which is the main characteristic of the helium Brayton cryo-refrigerator/cycle different from the air Brayton refrigerator/cycle. Other three characteristics also lie in the configuration of refrigerant helium bypass, internal purifier and non-linearity of specific heat of helium. Second, a model of helium Brayton cryo-refrigerator/cycle is presented according to finite-time thermodynamics. The assumption named internal purification temperature depth (PTD) is introduced, and the heat capacity rate of whole cycle is divided into three different regions in accordance with the PTD: room temperature region, upper internal purification temperature region and lower one. Analytical expressions of cooling capacity and COP are obtained, and we found that the expressions are piecewise functions. Further, comparison between the model and the experimental results for cooling capacity of the helium cryo-refrigerator shows that error is less than 7.6%. The PTD not only helps to achieve the analytical formulae and indicates the working

  15. Optimization of refrigeration machinery

    Energy Technology Data Exchange (ETDEWEB)

    Wall, Goeran [University Coll. of Eskilstuna/Vaesteraas (SE)

    1991-11-01

    This paper reports the application of thermoeconomics to the optimization of a heat pump. The method is suited for application to thermodynamic processes and yields exergy losses. The marginal cost of an arbitary variable can also be calculated. The efficiencies of the compressor, condenser, evaporator and electric motor are chosen as variables to be optimized. Parameters such as the price of electricity and the temperature of the delivered heat may vary between optimizations, and results are presented for different parameter values. The results show that the efficiency of the electric motor is the most important variable. (author).

  16. Krypton based adsorption type cryogenic refrigerator

    Science.gov (United States)

    Jones, Jack A. (Inventor); Schember, Helene R. (Inventor)

    1989-01-01

    Krypton and a monolithic porous carbon such as Saran carbon are used respectively as the sorbate and sorbent of an adsorption type refrigerator to improve refrigeration efficiency and operational longevity.

  17. REDUCING REFRIGERANT EMISSIONS FROM SUPERMARKET SYSTEMS

    Science.gov (United States)

    Large refrigeration systems are found in several applications including supermarkets, cold storage warehouses, and industrial processes. The sizes of these systems are a contributing factor to their problems of high refrigerant leak rates because of the thousands of connections, ...

  18. Thermoelectric refrigerator having improved temperature stabilization means

    International Nuclear Information System (INIS)

    Falco, C.M.

    1982-01-01

    A control system for thermoelectric refrigerators is disclosed. The thermoelectric refrigerator includes at least one thermoelectric element that undergoes a first order change at a predetermined critical temperature. The element functions as a thermoelectric refrigerator element above the critical temperature, but discontinuously ceases to function as a thermoelectric refrigerator element below the critical temperature. One example of such an arrangement includes thermoelectric refrigerator elements which are superconductors. The transition temperature of one of the superconductor elements is selected as the temperature control point of the refrigerator. When the refrigerator attempts to cool below the point, the metals become superconductors losing their ability to perform as a thermoelectric refrigerator. An extremely accurate, first-order control is realized

  19. Investigation of an experimental ejector refrigeration machine operating with refrigerant R245fa at design and off-design working conditions. Part 1. Theoretical analysis

    KAUST Repository

    Shestopalov, K.O.

    2015-07-01

    © 2015 Elsevier Ltd and IIR.All rights reserved. The ejector refrigeration machine (ERM) offers several advantages over other heat-driven refrigeration machine, including simplicity in design and operation, high reliability and low installation cost, which enable its wide application in the production of cooling. In this paper the theoretical analysis of ejector design and ejector refrigeration cycle performance is presented. It is shown that ERM performance characteristics depend strongly on the operating conditions, the efficiency of the ejector used, and the thermodynamic properties of the refrigerant used. A 1-D model for the prediction of the entrainment ratio ω, and an optimal design for ejectors with cylindrical and conical-cylindrical mixing chambers are presented in this paper. In order to increase ERM performance values, it is necessary first of all to improve the performance of the ejector.

  20. Finite time thermodynamics of power and refrigeration cycles

    CERN Document Server

    Kaushik, Shubhash C; Kumar, Pramod

    2017-01-01

    This book addresses the concept and applications of Finite Time Thermodynamics to various thermal energy conversion systems including heat engines, heat pumps, and refrigeration and air-conditioning systems. The book is the first of its kind, presenting detailed analytical formulations for the design and optimisation of various power producing and cooling cycles including but not limited to: • Vapour power cycles • Gas power cycles • Vapour compression cycles • Vapour absorption cycles • Rankine cycle coupled refrigeration systems Further, the book addresses the thermoeconomic analysis for the optimisation of thermal cycles, an important field of study in the present age and which is characterised by multi-objective optimization regarding energy, ecology, the environment and economics. Lastly, the book provides the readers with key techniques associated with Finite Time Thermodynamics, allowing them to understand the relevance of irreversibilitie s associated with real processes and the scientific r...

  1. Load forecasting for supermarket refrigeration

    DEFF Research Database (Denmark)

    Bacher, Peder; Madsen, Henrik; Aalborg Nielsen, Henrik

    This report presents a study of models for forecasting the load for supermarket refrigeration. The data used for building the forecasting models consists of load measurements, local climate measurements and weather forecasts. The load measurements are from a supermarket located in a village...... in Denmark. The load for refrigeration is the sum of all cabinets in the supermarket, both low and medium temperature cabinets, and spans a period of one year. As input to the forecasting models the ambient temperature observed near the supermarket together with weather forecasts are used. Every hour...

  2. Optimizing a Small Ammonia Heat Pump with Accumulator Tank for Space and Hot Tap Water Heating

    OpenAIRE

    Lalovs, Arturs

    2015-01-01

    The heat pump market offers a wide variety of different residential heat pumps where most of them utilize refrigerant R-410A which has high global warming potential. Considering the fact that global policy starts to focus on issues related to energy efficiency and harmful impact to the environment, it is necessary to investigate over new refrigerants. As an alternative solution is to utilize natural refrigerants, such as ammonia, which has almost zero glob...

  3. Magnetic Heat Pump Containing Flow Diverters

    Science.gov (United States)

    Howard, Frank S.

    1995-01-01

    Proposed magnetic heat pump contains flow diverters for suppression of undesired flows. If left unchecked, undesired flows mix substantial amounts of partially heated and partially cooled portions of working fluid, effectively causing leakage of heat from heated side to cooled side. By reducing leakage of heat, flow diverters increase energy efficiency of magnetic heat pump, potentially offering efficiency greater than compressor-driven refrigerator.

  4. Heat pump having improved defrost system

    Science.gov (United States)

    Chen, F.C.; Mei, V.C.; Murphy, R.W.

    1998-12-08

    A heat pump system includes, in an operable relationship for transferring heat between an exterior atmosphere and an interior atmosphere via a fluid refrigerant: a compressor; an interior heat exchanger; an exterior heat exchanger; an accumulator; and means for heating the accumulator in order to defrost the exterior heat exchanger. 2 figs.

  5. Refrigeration Cycle Design for Refrigerant Mixtures by Molecular Simulation

    Czech Academy of Sciences Publication Activity Database

    Smith, W.R.; Francová, Magda; Kowalski, M.; Nezbeda, Ivo

    2010-01-01

    Roč. 75, č. 4 (2010), s. 383-391 ISSN 0010-0765 R&D Projects: GA AV ČR IAA400720710 Grant - others:NSERC(CA) OGP1041 Institutional research plan: CEZ:AV0Z40720504 Keywords : refrigerants * molecular simulation s * vapor–liquid equilibrium Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.853, year: 2010

  6. Theoretical study on the effect of operating conditions on performance of absorption refrigeration system

    Energy Technology Data Exchange (ETDEWEB)

    Kaynakli, Omer; Kilic, Muhsin [Uludag University, Faculty of Engineering and Architecture, Department of Mechanical Engineering, TR-16059, Bursa (Turkey)

    2007-02-15

    In this study, a detailed thermodynamic analysis of the water/lithium bromide absorption refrigeration cycle is performed. The influences of operating temperature and effectiveness of heat exchanger on the thermal loads of components, coefficients of performance (COP{sub c}, COP) and efficiency ratio ({eta}) are investigated. It is concluded that the COP{sub c} and COP values increase with increasing generator and evaporator temperatures but decrease with increasing condenser and absorber temperatures. The {eta} value varies with these temperatures. Also, the effects of solution and refrigerant heat exchangers on the performance, efficiency ratio of the system and fluid temperatures are compared. As a result, it is found that the solution heat exchanger (SHE) has more effect on the investigated parameters than the refrigerant heat exchanger (RHE). While the SHE increases the COP value up to a maximum 44%, the RHE has an effect of only 2.8%. (author)

  7. 46 CFR 154.702 - Refrigerated carriage.

    Science.gov (United States)

    2010-10-01

    ... Pressure and Temperature Control § 154.702 Refrigerated carriage. (a) Each refrigeration system must: (1) Have enough capacity to maintain the cargo vapor pressure in each cargo tank served by the system below... the purpose of this section, a “refrigeration unit” includes a compressor and its motors and controls...

  8. 49 CFR 173.174 - Refrigerating machines.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Refrigerating machines. 173.174 Section 173.174 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS MATERIALS SAFETY... Refrigerating machines. A refrigerating machine assembled for shipment and containing 7 kg (15 pounds) or less...

  9. Solar Refrigerators Store Life-Saving Vaccines

    Science.gov (United States)

    2014-01-01

    Former Johnson Space Center engineer David Bergeron used his experience on the Advanced Refrigeration Technology Team to found SunDanzer Refrigeration Inc., a company specializing in solar-powered refrigerators. The company has created a battery-free unit that provides safe storage for vaccines in rural and remote areas around the world.

  10. Cryogenic refrigeration. (Latest citations from the NTIS Bibliographic database). Published Search

    International Nuclear Information System (INIS)

    1993-09-01

    The bibliography contains citations concerning the development and applications of cryogenic refrigeration technology. Citations discuss performance evaluations of specific systems, equipment descriptions, the cooling of instrumentation, superconducting devices, reactor devices, and applications in satellites and spaceborne vehicles. (Contains 250 citations and includes a subject term index and title list.)

  11. Cryogenic refrigeration. (Latest citations from the NTIS bibliographic database). Published Search

    International Nuclear Information System (INIS)

    1994-12-01

    The bibliography contains citations concerning the development and applications of cryogenic refrigeration technology. Citations discuss performance evaluations of specific systems, equipment descriptions, the cooling of instrumentation, superconducting devices, reactor devices, and applications in satellites and spaceborne vehicles. (Contains 250 citations and includes a subject term index and title list.)

  12. Magnetic Refrigeration Technology for High Efficiency Air Conditioning

    Energy Technology Data Exchange (ETDEWEB)

    Boeder, A; Zimm, C

    2006-09-30

    Magnetic refrigeration was investigated as an efficient, environmentally friendly, flexible alternative to conventional residential vapor compression central air conditioning systems. Finite element analysis (FEA) models of advanced geometry active magnetic regenerator (AMR) beds were developed to minimize bed size and thus magnet mass by optimizing geometry for fluid flow and heat transfer and other losses. Conventional and magnetocaloric material (MCM) regenerator fabrication and assembly techniques were developed and advanced geometry passive regenerators were built and tested. A subscale engineering prototype (SEP) magnetic air conditioner was designed, constructed and tested. A model of the AMR cycle, combined with knowledge from passive regenerator experiments and FEA results, was used to design the regenerator beds. A 1.5 Tesla permanent magnet assembly was designed using FEA and the bed structure and plenum design was extensively optimized using FEA. The SEP is a flexible magnetic refrigeration platform, with individually instrumented beds and high flow rate and high frequency capability, although the current advanced regenerator geometry beds do not meet performance expectations, probably due to manufacturing and assembly tolerances. A model of the AMR cycle was used to optimize the design of a 3 ton capacity magnetic air conditioner, and the system design was iterated to minimize external parasitic losses such as heat exchanger pressure drop and fan power. The manufacturing cost for the entire air conditioning system was estimated, and while the estimated SEER efficiency is high, the magnetic air conditioning system is not cost competitive as currently configured. The 3 ton study results indicate that there are other applications where magnetic refrigeration is anticipated to have cost advantages over conventional systems, especially applications where magnetic refrigeration, through the use of its aqueous heat transfer fluid, could eliminate intermediate

  13. 2013 German refrigeration and air conditioning meeting. Proceedings

    International Nuclear Information System (INIS)

    2013-01-01

    These proceedings cover the following main topics: cryoengineering - superconduction / energy storage; cryoapplications in biology and medicine; metrology; adsorption processes; condensation/evaporation; working fluids / simulation; ice production; plants and compressors; expansion and ejectors or recooling; use of cooling (passenger car air conditioning, supermarket); refrigerants; plant efficiency; emissions and legislation; air conditioning and use of heat pumps; air quality and control; building technology and block-type thermal power stations. [de

  14. The impact of urban morphology and land cover on the sensible heat flux retrieved by satellite and in-situ observations

    Science.gov (United States)

    Gawuc, L.; Łobocki, L.; Kaminski, J. W.

    2017-12-01

    Land surface temperature (LST) is a key parameter in various applications for urban environments research. However, remotely-sensed radiative surface temperature is not equivalent to kinetic nor aerodynamic surface temperature (Becker and Li, 1995; Norman and Becker, 1995). Thermal satellite observations of urban areas are also prone to angular anisotropy which is directly connected with the urban structure and relative sun-satellite position (Hu et al., 2016). Sensible heat flux (Qh) is the main component of surface energy balance in urban areas. Retrieval of Qh, requires observations of, among others, a temperature gradient. The lower level of temperature measurement is commonly replaced by remotely-sensed radiative surface temperature (Chrysoulakis, 2003; Voogt and Grimmond, 2000; Xu et al., 2008). However, such replacement requires accounting for the differences between aerodynamic and radiative surface temperature (Chehbouni et al., 1996; Sun and Mahrt, 1995). Moreover, it is important to avoid micro-scale processes, which play a major role in the roughness sublayer. This is due to the fact that Monin-Obukhov similarity theory is valid only in dynamic sublayer. We will present results of the analyses of the impact of urban morphology and land cover on the seasonal changes of sensible heat flux (Qh). Qh will be retrieved by two approaches. First will be based on satellite observations of radiative surface temperature and second will be based on in-situ observations of kinetic road temperature. Both approaches will utilize wind velocity, and air temperature observed in-situ. We will utilize time series of MODIS LST observations for the period of 2005-2014 as well as simultaneous in-situ observations collected by road weather network (9 stations). Ground stations are located across the city of Warsaw, outside the city centre in low-rise urban structure. We will account for differences in urban morphology and land cover in the proximity of ground stations. We will

  15. KSTAR Helium Refrigeration System Design and Manufacturing

    International Nuclear Information System (INIS)

    Dauguet, P.; Briend, P.; Abe, I.; Fauve, E.; Bernhardt, J.-M.; Andrieu, F.; Beauvisage, J.

    2006-01-01

    The tokamak developed in the KSTAR (Korean Superconducting Tokamak Advanced Research) project makes intensive use of superconducting magnets operated at 4.5 K. The cold components of the KSTAR tokamak require forced flow of supercritical helium for magnets/structure, boiling liquid helium for current leads, and gaseous helium for thermal shields. The cryogenic system will provide stable operation and full automatic control. A three-pressure helium cycle composed of six turbines has been customised design for this project. The '' design '' operating mode results with a system composed of a 9 kW refrigerator (including safety margin) and using gas and liquid storages for mass balancing. During Shot/Standby mode, the heat loads are highly time-dependent. A thermal damper is used to smooth these variations and will allow stable operation. (author)

  16. Review of SC/RF refrigeration systems

    International Nuclear Information System (INIS)

    Byrns, R.A.

    1990-01-01

    A short review is given of historical events in accelerator and cryogenic developments at both Stanford and Berkeley. Methods of refrigeration between 1.85 K and 4.5 K together with modern techniques and improvements are discussed. Where the decade of the 70's was the era of the screw compressor, the 80's can be considered that of the cold vacuum pump for superfluid cooling. Distribution methods are of major importance, and arguments can be made for bath or tube cooling, two-phase, thermo-syphon, supercritical or superfluid. System design affects reliability, safety and operating stability. Distribution costs and heat loads can be a large part of system totals. Some specific system descriptions are included. (author)

  17. Thermodynamic performance optimization of the absorption-generation process in an absorption refrigeration cycle

    International Nuclear Information System (INIS)

    Chen, Yi; Han, Wei; Jin, Hongguang

    2016-01-01

    Highlights: • This paper proposes a new thermal compressor model with boost pressure ratio. • The proposed model is an effective way to optimize the absorption-generation process. • Boost pressure ratio is a key parameter in the proposed thermal compressor model. • The optimum boost pressure ratios for two typical refrigeration systems are obtained. - Abstract: The absorption refrigeration cycle is a basic cycle that establishes the systems for utilizing mid-low temperature heat sources. A new thermal compressor model with a key parameter of boost pressure ratio is proposed to optimize the absorption-generation process. The ultimate generation pressure and boost pressure ratio are used to represent the potential and operating conditions of the thermal compressor, respectively. Using the proposed thermal compressor model, the operation mechanism and requirements of the absorption refrigeration system and absorption-compression refrigeration system are elucidated. Furthermore, the two typical heat conversion systems are optimized based on the thermal compressor model. The optimum boost pressure ratios of the absorption refrigeration system and the absorption-compression refrigeration system are 0.5 and 0.75, respectively. For the absorption refrigeration system, the optimum generation temperature is 125.31 °C at the cooling water temperature of 30 °C, which is obtained by simple thermodynamic calculation. The optimized thermodynamic performance of the absorption-compression refrigeration system is 16.7% higher than that of the conventional absorption refrigeration system when the generation temperature is 100 °C. The thermal compressor model proposed in this paper is an effective method for simplifying the optimization of the thermodynamic systems involving an absorption-generation process.

  18. A solar absorption refrigerator

    Energy Technology Data Exchange (ETDEWEB)

    Kurbanov, N.; Daykhanov, S.; Khandurdyev, A.

    1982-01-01

    An assembly is described which is designed primarily for air conditioning. This device contains a transformer heated by solar energy, a heat exchanger generator with strong and weak solution lines connected to the irrigator and absorber vessel, respectively, and an evaporator. In order to reduce the metal consumption, the absorber and the evaporator are built in the form of a single indirectly air-cooled device with vertical dry and wet channels for primary and auxillary air respectively. The absorber irrigator is manufactured in a multisectional configuration with its sections located in the upper half of the front section of each dry channel, with the lower sections of these areas manufactured as a weak solution vessel separated from the remaining sections containing the dry channels by barriers.

  19. General performance characteristics of an irreversible ferromagnetic Stirling refrigeration cycle

    International Nuclear Information System (INIS)

    Lin, G.; Tegus, O.; Zhang, L.; Brueck, E.

    2004-01-01

    A new magnetic-refrigeration-cycle model using ferromagnetic materials as a cyclic working substance is set up, in which finite-rate heat transfer, heat leak and regeneration time are taken into account. On the basis of the thermodynamic properties of a ferromagnetic material, the general performance characteristics of the ferromagnetic Stirling refrigeration cycle are investigated and the effects of some key irreversibilities on the performance of the cycle are revealed. By using the optimal-control theory, the optimal relation between the coefficient of performance and the cooling rate is derived and some important performance bounds, e.g., the maximum cooling rate, the maximum coefficient of performance, are determined. Moreover, the optimal operating regions for cooling rate, coefficient of performance and the optimal operating temperatures of a cyclic working substance in the two heat-transfer processes are obtained. Furthermore, the influences of magnetization and magnetic field on the performance characteristics of the cycle are discussed. The results obtained here have general significance and can be deduced to the related ones of the Stirling refrigeration cycle using paramagnetic salt as a cyclic working substance

  20. High Efficiency, Low Emission Refrigeration System

    Energy Technology Data Exchange (ETDEWEB)

    Fricke, Brian A [ORNL; Sharma, Vishaldeep [ORNL

    2016-08-01

    Supermarket refrigeration systems account for approximately 50% of supermarket energy use, placing this class of equipment among the highest energy consumers in the commercial building domain. In addition, the commonly used refrigeration system in supermarket applications is the multiplex direct expansion (DX) system, which is prone to refrigerant leaks due to its long lengths of refrigerant piping. This leakage reduces the efficiency of the system and increases the impact of the system on the environment. The high Global Warming Potential (GWP) of the hydrofluorocarbon (HFC) refrigerants commonly used in these systems, coupled with the large refrigerant charge and the high refrigerant leakage rates leads to significant direct emissions of greenhouse gases into the atmosphere. Methods for reducing refrigerant leakage and energy consumption are available, but underutilized. Further work needs to be done to reduce costs of advanced system designs to improve market utilization. In addition, refrigeration system retrofits that result in reduced energy consumption are needed since the majority of applications address retrofits rather than new stores. The retrofit market is also of most concern since it involves large-volume refrigerant systems with high leak rates. Finally, alternative refrigerants for new and retrofit applications are needed to reduce emissions and reduce the impact on the environment. The objective of this Collaborative Research and Development Agreement (CRADA) between the Oak Ridge National Laboratory and Hill Phoenix is to develop a supermarket refrigeration system that reduces greenhouse gas emissions and has 25 to 30 percent lower energy consumption than existing systems. The outcomes of this project will include the design of a low emission, high efficiency commercial refrigeration system suitable for use in current U.S. supermarkets. In addition, a prototype low emission, high efficiency supermarket refrigeration system will be produced for

  1. Numerical simulation of a three-stage Stirling-type pulse-tube refrigerator

    NARCIS (Netherlands)

    Etaati, M.A.

    2011-01-01

    The pulse-tube refrigerator (PTR) is a rather new device for cooling down to extremely low temperatures, i.e. below 4 K. The PTR works by the cyclic compression and expansion of helium that flows through a regenerator made of porous material, a cold heat exchanger, a tube, a hot heat exchanger and

  2. Eco-Friendly Alternative Refrigeration Systems -R-ES-O-N-A-N--CE ...

    Indian Academy of Sciences (India)

    An electrical signal may be converted to acoustical (i.e. ... Thermoacoustic Refrigeration System. In a simple ... Tc and rejecting Wclste heat power Qh to a heat sink at T h. •. In .... use where eco-friendliness, simplicity, reliability or low cost is.

  3. 2016 German refrigeration and air conditioning meeting. Proceedings; Deutsche Kaelte- und Klimatagung 2016. Tagungsbericht

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2016-07-01

    The following topics were dealt with: Large cryogenic facilities, relief valves, liquid helium, liquid-nitrogen and liquid hydrogen cooling, new concepts, foundations and materials of the heat-pump techniques, evaporation, phase-change materials, absorption, afterheat usage, ionic liquids, sorption, condensers, heat exchangers, back-cooling systems, refrigerants, caron dioxide, mobile applications, efficiency and optimization, air conditioning.

  4. Principles of Refrigeration. Automotive Mechanics. Air Conditioning. Instructor's Guide [and] Student Guide.

    Science.gov (United States)

    Spignesi, B.

    This instructional package, one in a series of individualized instructional units on automobile air conditioning, consists of a student guide and an instructor guide dealing with the principles of refrigeration. Covered in the module are defining the term heat, defining the term British Thermal Unit (BTU), defining the term latent heat, listing…

  5. New Regenerative Cycle for Vapor Compression Refrigeration

    Energy Technology Data Exchange (ETDEWEB)

    Mark J. Bergander

    2005-08-29

    second step of compression. In the proposed system, the compressor compresses the vapor only to 50-60% of the final pressure, while the additional compression is provided by a jet device using internal potential energy of the working fluid flow. Therefore, the amount of mechanical energy required by a compressor is significantly reduced, resulting in the increase of efficiency (either COP or EER). The novelty of the cycle is in the equipment and in the way the multi-staging is accomplished. The anticipated result will be a new refrigeration system that requires less energy to accomplish a cooling task. The application of this technology will be for more efficient designs of: (1) Industrial chillers, (2) Refrigeration plants, (3) Heat pumps, (4) Gas Liquefaction plants, (5) Cryogenic systems.

  6. Industrial trigeneration using ammonia-water absorption refrigeration systems (AAR)

    International Nuclear Information System (INIS)

    Colonna, Piero; Gabrielli, Sandro

    2003-01-01

    In many industrial processes there is a simultaneous need for electric power and refrigeration at low temperatures. Examples are in the food and chemical industries. Nowadays the increase in fuel prices and the ecological implications are giving an impulse to energy technologies that better exploit the primary energy source and integrated production of utilities should be considered when designing a new production plant. The number of so-called trigeneration systems installations (electric generator and absorption refrigeration plant) is increasing. If low temperature refrigeration is needed (from 0 to -40 deg. C), ammonia-water absorption refrigeration plants can be coupled to internal combustion engines or turbogenerators. A thermodynamic system study of trigeneration configurations using a commercial software integrated with specifically designed modules is presented. The study analyzes and compares heat recovery from the primary mover at different temperature levels. In the last section a simplified economic assessment that takes into account disparate prices in European countries compares conventional electric energy supply from the grid and optimized trigeneration plants in one test case (10 MW electric power, 7000 h/year)

  7. Stability of split Stirling refrigerators

    NARCIS (Netherlands)

    Waele, de A.T.A.M.; Liang, W.

    2009-01-01

    In many thermal systems spontaneous mechanical oscillations are generated under the influence of large temperature gradients. Well-known examples are Taconis oscillations in liquid-helium cryostats and oscillations in thermoacoustic systems. In split Stirling refrigerators the compressor and the

  8. Utilization of satellite remote sensing data on land surface characteristics in water and heat balance component modeling for vegetation covered territories

    Science.gov (United States)

    Muzylev, Eugene; Uspensky, Alexander; Startseva, Zoya; Volkova, Elena; Kukharsky, Alexander; Uspensky, Sergey

    2010-05-01

    The model of vertical water and heat transfer in the "soil-vegetation-atmosphere" system (SVAT) for vegetation covered territory has been developed, allowing assimilating satellite remote sensing data on land surface condition as well as accounting for heterogeneities of vegetation and meteorological characteristics. The model provides the calculation of water and heat balance components (such as evapotranspiration Ev, soil water content W, sensible and latent heat fluxes and others ) as well as vertical soil moisture and temperature distributions, temperatures of soil surface and foliage, land surface brightness temperature for any time interval within vegetation season. To describe the landscape diversity soil constants and leaf area index LAI, vegetation cover fraction B, and other vegetation characteristics are used. All these values are considered to be the model parameters. Territory of Kursk region with square about 15 thousands km2 situated in the Black Earth zone of Central Russia was chosen for investigation. Satellite-derived estimates of land surface characteristics have been constructed under cloud-free condition basing AVHRR/NOAA, MODIS/EOS Terra and EOS Aqua, SEVIRI/Meteosat-8, -9 data. The developed technologies of AVHRR data thematic processing have been refined providing the retrieval of surface skin brightness temperature Tsg, air foliage temperature Ta, efficient surface temperature Ts.eff and emissivity E, as well as derivation of vegetation index NDVI, B, and LAI. The linear regression estimators for Tsg, Ta and LAI have been built using representative training samples for 2003-2009 vegetation seasons. The updated software package has been applied for AVHRR data thematic processing to generate named remote sensing products for various dates of the above vegetation seasons. The error statistics of Ta, Ts.eff and Тsg derivation has been investigated for various samples using comparison with in-situ measurements that has given RMS errors in the

  9. Environment-friendly refrigeration - Switzerland moves forward

    International Nuclear Information System (INIS)

    Stohler, F.

    2003-01-01

    This article presents an interview with Silvan Schaller, president of the Swiss Refrigeration Society SVK and head of a leading Swiss industrial refrigeration company, on the subject of the implementation of new Swiss materials legislation that regulates the use of various refrigerants. In particular, the co-operation between the Society and the regulatory authorities is stressed. The reasons behind the regulations - the protection of the environment and, in particular, the ozone layer - are discussed as are the efforts required by industry to meet them. Future refrigeration technologies and the choice of refrigerants are examined. Measures that will have to be taken by the companies in the refrigeration sector, such as the additional training of personnel and the monitoring of the disposal of wastes, are examined. For the future, the goal of reducing the energy consumption of refrigeration installations is noted

  10. Magnon-driven quantum dot refrigerators

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yuan; Huang, Chuankun; Liao, Tianjun; Chen, Jincan, E-mail: jcchen@xmu.edu.cn

    2015-12-18

    Highlights: • A three-terminal quantum dot refrigerator is proposed. • The effects of magnetic field, applied voltage, and polarization are considered. • The region that the system can work as a refrigerator is determined. • Two different magnon-driven quantum dot refrigerators are compared. - Abstract: A new model of refrigerator consisting of a spin-splitting quantum dot coupled with two ferromagnetic reservoirs and a ferromagnetic insulator is proposed. The rate equation is used to calculate the occupation probabilities of the quantum dot. The expressions of the electron and magnon currents are obtained. The region that the system can work in as a refrigerator is determined. The cooling power and coefficient of performance (COP) of the refrigerator are derived. The influences of the magnetic field, applied voltage, and polarization of two leads on the performance are discussed. The performances of two different magnon-driven quantum dot refrigerators are compared.

  11. Demonstration of the Use of Remote Temperature Monitoring Devices in Vaccine Refrigerators in Haiti.

    Science.gov (United States)

    Cavallaro, Kathleen F; Francois, Jeannot; Jacques, Roody; Mentor, Derline; Yalcouye, Idrissa; Wilkins, Karen; Mueller, Nathan; Turner, Rebecca; Wallace, Aaron; Tohme, Rania A

    After the 2010 earthquake, Haiti committed to introducing 4 new antigens into its routine immunization schedule, which required improving its cold chain (ie, temperature-controlled supply chain) and increasing vaccine storage capacity by installing new refrigerators. We tested the feasibility of using remote temperature monitoring devices (RTMDs) in Haiti in a sample of vaccine refrigerators fueled by solar panels, propane gas, or electricity. We analyzed data from 16 RTMDs monitoring 24 refrigerators in 15 sites from March through August 2014. Although 5 of the 16 RTMDs exhibited intermittent data gaps, we identified typical temperature patterns consistent with refrigerator door opening and closing, propane depletion, thermostat insufficiency, and overstocking. Actual start-up, annual maintenance, and annual electricity costs for using RTMDs were $686, $179, and $9 per refrigerator, respectively. In Haiti, RTMD use was feasible. RTMDs could be prioritized for use with existing refrigerators with high volumes of vaccines and new refrigerators to certify their functionality before use. Vaccine vial monitors could provide additional useful information about cumulative heat exposure and possible vaccine denaturation.

  12. Potential benefits of saturation cycle with two-phase refrigerant injection

    International Nuclear Information System (INIS)

    Lee, Hoseong; Hwang, Yunho; Radermacher, Reinhard; Chun, Ho-Hwan

    2013-01-01

    In this paper, a saturation cycle is proposed to enhance a vapor compression cycle performance by reducing thermodynamic losses associated with single phase gas compression and isenthalpic expansion. In order to approach the saturation cycle, a two-phase refrigerant injection technique is applied to the multi-stage cycle. This multi-stage cycle with different options is modeled, and its performance is evaluated under ASHRAE standard operating conditions for air conditioning systems. Moreover, the two-phase refrigerant injection cycle is compared with the typical vapor injection cycle which is utilizing the internal heat exchanger or the flash tank. Low GWP refrigerants are applied to this two-phase refrigerant injection cycle. In terms of the COP and its improvement, R123 has a higher potential than any other refrigerants in the multi-stage cycle. Lastly, practical ideas realizing the saturation cycle are discussed such as multi-stage phase separator, phase separator with helical structure inside, and injection location of the compressor. -- Highlights: • A saturation cycle is proposed to enhance the vapor compression cycle performance. • Two-phase refrigerant injection technique is applied to the multi-stage cycle. • Modeling results of the proposed cycle show the significant performance improvement. • Low GWP refrigerants are applied and R123 shows the highest performance. • New parameters, α and ε, are used to show the potential of the saturation cycle

  13. Knowledge based decision making method for the selection of mixed refrigerant systems for energy efficient LNG processes

    International Nuclear Information System (INIS)

    Khan, Mohd Shariq; Lee, Sanggyu; Rangaiah, G.P.; Lee, Moonyong

    2013-01-01

    Highlights: • Practical method for finding optimum refrigerant composition is proposed for LNG plant. • Knowledge of boiling point differences in refrigerant component is employed. • Implementation of process knowledge notably makes LNG process energy efficient. • Optimization of LNG plant is more transparent using process knowledge. - Abstract: Mixed refrigerant (MR) systems are used in many industrial applications because of their high energy efficiency, compact design and energy-efficient heat transfer compared to other processes operating with pure refrigerants. The performance of MR systems depends strongly on the optimum refrigerant composition, which is difficult to obtain. This paper proposes a simple and practical method for selecting the appropriate refrigerant composition, which was inspired by (i) knowledge of the boiling point difference in MR components, and (ii) their specific refrigeration effect in bringing a MR system close to reversible operation. A feasibility plot and composite curves were used for full enforcement of the approach temperature. The proposed knowledge-based optimization approach was described and applied to a single MR and a propane precooled MR system for natural gas liquefaction. Maximization of the heat exchanger exergy efficiency was considered as the optimization objective to achieve an energy efficient design goal. Several case studies on single MR and propane precooled MR processes were performed to show the effectiveness of the proposed method. The application of the proposed method is not restricted to liquefiers, and can be applied to any refrigerator and cryogenic cooler where a MR is involved

  14. Transient Analysis of a Magnetic Heat Pump

    Science.gov (United States)

    Schroeder, E. A.

    1985-01-01

    An experimental heat pump that uses a rare earth element as the refrigerant is modeled using NASTRAN. The refrigerant is a ferromagnetic metal whose temperature rises when a magnetic field is applied and falls when the magnetic field is removed. The heat pump is used as a refrigerator to remove heat from a reservoir and discharge it through a heat exchanger. In the NASTRAN model the components modeled are represented by one-dimensional ROD elements. Heat flow in the solids and fluid are analyzed. The problem is mildly nonlinear since the heat capacity of the refrigerant is temperature-dependent. One simulation run consists of a series of transient analyses, each representing one stroke of the heat pump. An auxiliary program was written that uses the results of one NASTRAN analysis to generate data for the next NASTRAN analysis.

  15. When are solar refrigerators less costly than on-grid refrigerators: A simulation modeling study.

    Science.gov (United States)

    Haidari, Leila A; Brown, Shawn T; Wedlock, Patrick; Connor, Diana L; Spiker, Marie; Lee, Bruce Y

    2017-04-19

    Gavi recommends solar refrigerators for vaccine storage in areas with less than eight hours of electricity per day, and WHO guidelines are more conservative. The question remains: Can solar refrigerators provide value where electrical outages are less frequent? Using a HERMES-generated computational model of the Mozambique routine immunization supply chain, we simulated the use of solar versus electric mains-powered refrigerators (hereafter referred to as "electric refrigerators") at different locations in the supply chain under various circumstances. At their current price premium, the annual cost of each solar refrigerator is 132% more than each electric refrigerator at the district level and 241% more at health facilities. Solar refrigerators provided savings over electric refrigerators when one-day electrical outages occurred more than five times per year at either the district level or the health facilities, even when the electric refrigerator holdover time exceeded the duration of the outage. Two-day outages occurring more than three times per year at the district level or more than twice per year at the health facilities also caused solar refrigerators to be cost saving. Lowering the annual cost of a solar refrigerator to 75% more than an electric refrigerator allowed solar refrigerators to be cost saving at either level when one-day outages occurred more than once per year, or when two-day outages occurred more than once per year at the district level or even once per year at the health facilities. Our study supports WHO and Gavi guidelines. In fact, solar refrigerators may provide savings in total cost per dose administered over electrical refrigerators when electrical outages are less frequent. Our study identified the frequency and duration at which electrical outages need to occur for solar refrigerators to provide savings in total cost per dose administered over electric refrigerators at different solar refrigerator prices. Copyright © 2017. Published

  16. Parametric analysis for a new combined power and ejector-absorption refrigeration cycle

    International Nuclear Information System (INIS)

    Wang Jiangfeng; Dai Yiping; Zhang Taiyong; Ma Shaolin

    2009-01-01

    A new combined power and ejector-absorption refrigeration cycle is proposed, which combines the Rankine cycle and the ejector-absorption refrigeration cycle, and could produce both power output and refrigeration output simultaneously. This combined cycle, which originates from the cycle proposed by authors previously, introduces an ejector between the rectifier and the condenser, and provides a performance improvement without greatly increasing the complexity of the system. A parametric analysis is conducted to evaluate the effects of the key thermodynamic parameters on the cycle performance. It is shown that heat source temperature, condenser temperature, evaporator temperature, turbine inlet pressure, turbine inlet temperature, and basic solution ammonia concentration have significant effects on the net power output, refrigeration output and exergy efficiency of the combined cycle. It is evident that the ejector can improve the performance of the combined cycle proposed by authors previously.

  17. Heat treatment and gamma radiation effects on the physical-chemical, microbiological and sensory stability of pure sugarcane juice or added with fruit juices, stored under refrigeration;Efeitos do processamento termico e da radiacao gama na estabilidade fisico-quimica, microbiologica e sensorial de caldo de cana puro e adicionado de suco de frutas, armazenado sob refrigeracao

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Aline Cristine Garcia de

    2007-07-01

    Sugarcane juice is a taste drink, energetic, no alcoholic that conserves all the nutrients in cane sugar. It was very appreciated by the Brazilian population and its production has been shown to be a highly lucrative business. This research had the following objectives: evaluate the acceptance of the consuming market and the stability of pure sugarcane juice or added with natural fruit juices, submitted of heat treatment (70 deg C/ 25 min) and/ or gamma radiation (2,5 kGy) and stored in high density polyethylene bottles, under refrigeration (5 +- 1 deg C). Sugarcane juice market test was evaluated through the application of 350 questionnaires on six Sao Paulo cities. Sugarcane juice stability was evaluated through microbiological (psychotropic count, lactic bacteria and yeasts and molds count), physical-chemical (pH, color, titratable acidity, soluble solids, ratio and polyphenoloxidase activity) and sensory (hedonic test) parameters. Centesimal composition was determined analyzing: humidity, caloric value, total carbohydrates, total and reducing sugars, lipids, proteins, ascorbic acid, ash and minerals. Sugarcane juice shelf life period was determinate ever 7 days over a period of 42 days stored under refrigeration. The data were submitted to the variance analysis and compared by Tukey's test (p<0,05). Among the 350 interviewed people, more of the half one is interested about its habitual food safe and care about street foods. Sandwiches had been cited foods as routinely consumed, followed for the sugarcane juice and 'pastel'. Among the interviewed ones, 80% had mentioned to appreciate sugarcane juice. It had not correlation between age and school age and the preference for the consumption form was with lemon juice addition. About 55% of the interviewed ones had mentioned that would more frequently consume sugarcane juice processed and packed. Sugarcane juice processing did not modify the flavor and taste of the drink. It was concluded from the

  18. Multi-ejector concept for R-744 supermarket refrigerators; Multi-Ejektoren Konzept fuer R-744 Supermarkt-Kaelteanlagen

    Energy Technology Data Exchange (ETDEWEB)

    Hafner, Armin [SINTEF Energy Research, Trondheim (Norway); Foersterling, Sven [TLK-Thermo GmbH, Braunschweig (Germany); Banasiak, Krzystof [Silesian Univ. of Technology, Gliwice (Poland)

    2012-07-01

    Supermarkets are commercial buildings with major energy consumption and contribute also to relatively large direct emissions of greenhouse (GHG) through emissions of refrigerants from the refrigeration plants and the air conditioning system installed. The huge majority of these systems, which are installed in European supermarkets, are applying HFC-404A as working fluid. Average annual leakage rates in Europe are in the range of 15-20 % of the total charge. Worldwide the figure is about 30 % and HCFC-22 being the main refrigerant in use. Restrictions on the use of synthetic refrigerants are coming into force in several countries. There is a need for a natural refrigerant which allows for a safe investment in efficient refrigeration systems which will not be forced to be retrofitted by legislation in the future. Systems applying R-744 as the only refrigerant have been developed and more than 500 supermarkets exist in Europe, mainly in northern and mid-European countries. However, the systems still have large potential in development with respect to energy efficiency, heat recovery and cost efficiency. The paper describes the calculation method to identify the possible annual energy savings for different supermarket systems layout. The adoption of non-controlled ejectors and additional function such as heat recovery are evaluated. Results show relevant improvements in system efficiency when heat recovery has been adopted. Ejector usage is not widely spread at the moment. Thus, a theoretical analysis applying the programming language Modelica has been carried out. (orig.)

  19. Modelling of domestic refrigerators' energy consumption under real life conditions in Europe

    Energy Technology Data Exchange (ETDEWEB)

    Geppert, Jasmin

    2011-05-23

    In recent decades, energy and resource savings have become increasingly important, not only in the industrial, but also the residential sector. As one of the largest energy users in private homes, domestic refrigerators and freezers were among the first appliances to be targeted for energy efficiency improvements. With the aim of encouraging manufacturers to develop and produce more efficient appliances, the European Energy Label was introduced in the mid-nineties. However, the energy use of refrigerators does not only depend on technical components and features. Especially the using conditions in private homes are of a decisive influence. Thus, the present study has been conducted to test the sensitivity of refrigerators' energy consumption to various usage conditions within realistic ranges, which have been determined by means of two empirical studies. Key information gathered from the experiments were used as a base for the development and validation of a simplified model that allows predicting the energy consumption of refrigerators in use. The practical experiments were performed under controlled laboratory conditions with four different refrigerators with an A{sup +} or A{sup ++} energy efficiency rating (two statically cooled built-in fridge-freezers, one dynamically cooled refrigerator and one statically cooled refrigerator). The investigations revealed that the ambient temperature has the greatest impact on a refrigerator's energy consumption, followed by thermostat setting and heat load by insertion of warm items. The refrigerators' load under static conditions as well as the number of door openings have almost no impact on energy consumption. The modelling methodology follows a first-principle approach adjusted by experimental data. When compared to experimental results, model predictions show a reasonable agreement for the whole range of investigated conditions. (orig.)

  20. Heating of the quiet solar corona from measurements of the FET/TESIS instrument on-board the KORONAS-FOTON satellite

    Science.gov (United States)

    Rybák, J.; Gömöry, P.; Benz, A.; Bogachev, P.; Brajša, R.

    2010-12-01

    The paper presents the first results of the observations of time evolution of the quiet solar corona brightenings obtained due to very rapid photography of the corona with full-disk EUV telescopes of the FET/TESIS instrument onboard the KORONA FOTON satellite. The measurements were performed simultaneously in the emission of the Fe IX / X 17.1 and Fe VIII 13.1 spectral lines with 10 second temporal cadence and spatial scale of 1.7 arc seconds within one hour. This test observation, carried out on 15 July 2009, was analyzed in order to determine whether this type of observation can be used to identify individual microevents in the solar corona heating that are above the tresholds of spatial and temporal resolutions of the observations of non-active regions in the solar atmosphere. For this purpose, a simple method was used involving cross-correlation of the plasma emission time evolution at different temperatures, each time from observations of identical elements. The results obtained are confronted with the expected observable manifestations of the corona heating via nanoflares. TESIS is a set of instruments for the Sun photography developed in the Lebedev Physics Institute of the Russian Academy of Sciences that was launched into orbit in January 2009.

  1. Integrated Refrigeration and Storage for Advanced Liquid Hydrogen Operations

    Science.gov (United States)

    Swanger, A. M.; Notardonato, W. U.; Johnson, W. L.; Tomsik, T. M.

    2016-01-01

    NASA has used liquefied hydrogen (LH2) on a large scale since the beginning of the space program as fuel for the Centaur and Apollo upper stages, and more recently to feed the three space shuttle main engines. The LH2 systems currently in place at the Kennedy Space Center (KSC) launch pads are aging and inefficient compared to the state-of-the-art. Therefore, the need exists to explore advanced technologies and operations that can drive commodity costs down, and provide increased capabilities. The Ground Operations Demonstration Unit for Liquid Hydrogen (GODU-LH2) was developed at KSC to pursue these goals by demonstrating active thermal control of the propellant state by direct removal of heat using a cryocooler. The project has multiple objectives including zero loss storage and transfer, liquefaction of gaseous hydrogen, and densification of liquid hydrogen. The key technology challenge was efficiently integrating the cryogenic refrigerator into the LH2 storage tank. A Linde LR1620 Brayton cycle refrigerator is used to produce up to 900W cooling at 20K, circulating approximately 22 g/s gaseous helium through the hydrogen via approximately 300 m of heat exchanger tubing. The GODU-LH2 system is fully operational, and is currently under test. This paper will discuss the design features of the refrigerator and storage system, as well as the current test results.

  2. The performance of the first Jordan Badia's solar powered refrigerator

    International Nuclear Information System (INIS)

    Mohammed Awwad Al-Dabbas

    2012-01-01

    We are facing a significant challenge in Jordan's Badia region. Such challenge present us given that it will be environmentally protected with easy access to the refrigeration process to food and medical vaccines keeping at a reasonably and economical low cost. Solar cooling method that is generated from the sun as a substitute for batteries or electrical power is characteristic of its kind to store a power system for continued use. A pilot project of solar refrigerator was tested to collect technological data on a standard basis so the method control tests are accurate and precise. Solar refrigerator does not require electricity, which utilizes a combination of heat conduction and convection. In addition, it can be made from readily available material such as cardboard, sand, and recycled metal. It is constructed from two cylinders: an inner metal cylinder, fitted inside, and an outer cylinder that can be made of wood or plastic, etc, and organic material such as (sand, wool, or soil) placed in the left space between the two cylinders which is then saturated with water. As heat from the sun evaporates the water, the inner chamber is cooled to reduce and maintains the temperature at (6 degree C). (authors)

  3. A compact rotating dilution refrigerator

    Science.gov (United States)

    Fear, M. J.; Walmsley, P. M.; Chorlton, D. A.; Zmeev, D. E.; Gillott, S. J.; Sellers, M. C.; Richardson, P. P.; Agrawal, H.; Batey, G.; Golov, A. I.

    2013-10-01

    We describe the design and performance of a new rotating dilution refrigerator that will primarily be used for investigating the dynamics of quantized vortices in superfluid 4He. All equipment required to operate the refrigerator and perform experimental measurements is mounted on two synchronously driven, but mechanically decoupled, rotating carousels. The design allows for relative simplicity of operation and maintenance and occupies a minimal amount of space in the laboratory. Only two connections between the laboratory and rotating frames are required for the transmission of electrical power and helium gas recovery. Measurements on the stability of rotation show that rotation is smooth to around 10-3 rad s-1 up to angular velocities in excess of 2.5 rad s-1. The behavior of a high-Q mechanical resonator during rapid changes in rotation has also been investigated.

  4. When are solar refrigerators less costly than on-grid refrigerators: A simulation modeling study☆

    Science.gov (United States)

    Haidari, Leila A.; Brown, Shawn T.; Wedlock, Patrick; Connor, Diana L.; Spiker, Marie; Lee, Bruce Y.

    2017-01-01

    Background Gavi recommends solar refrigerators for vaccine storage in areas with less than eight hours of electricity per day, and WHO guidelines are more conservative. The question remains: Can solar refrigerators provide value where electrical outages are less frequent? Methods Using a HERMES-generated computational model of the Mozambique routine immunization supply chain, we simulated the use of solar versus electric mains-powered refrigerators (hereafter referred to as “electric refrigerators”) at different locations in the supply chain under various circumstances. Results At their current price premium, the annual cost of each solar refrigerator is 132% more than each electric refrigerator at the district level and 241% more at health facilities. Solar refrigerators provided savings over electric refrigerators when one-day electrical outages occurred more than five times per year at either the district level or the health facilities, even when the electric refrigerator holdover time exceeded the duration of the outage. Two-day outages occurring more than three times per year at the district level or more than twice per year at the health facilities also caused solar refrigerators to be cost saving. Lowering the annual cost of a solar refrigerator to 75% more than an electric refrigerator allowed solar refrigerators to be cost saving at either level when one-day outages occurred more than once per year, or when two-day outages occurred more than once per year at the district level or even once per year at the health facilities. Conclusion Our study supports WHO and Gavi guidelines. In fact, solar refrigerators may provide savings in total cost per dose administered over electrical refrigerators when electrical outages are less frequent. Our study identified the frequency and duration at which electrical outages need to occur for solar refrigerators to provide savings in total cost per dose administered over electric refrigerators at different solar

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

    Science.gov (United States)

    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. Subsurface Thermal Energy Storage for Improved Heating and Air Conditioning Efficiency

    Science.gov (United States)

    2016-11-21

    through water evaporation , although some cooling also occurs due to sensible heat transfer . Cooling towers are very effective heat transfer devices... evaporator coil connected to the building heating , ventilation, and air conditioning (HVAC) system. The refrigerant evaporates in the coil, removing...vapor is directed to a condensing coil, where the refrigerant vapor condenses back into a liquid, releasing its heat of vaporization. During

  7. Industrial Heat Pump for a High Temperature District Heating Application

    DEFF Research Database (Denmark)

    Poulsen, Claus Nørgaard

    by excess thermal energy from thermal solar panels. An industrial heat pump system using the natural refrigerant ammonia, is extracting the thermal energy from the storage when needed, and produce hot water at 85°C, for the district heating grid. The heat pump also acts as contributor to electricity grid...

  8. The use of cold storage in household refrigerators

    International Nuclear Information System (INIS)

    Michael, Y.C.; Yang, K.T.

    1991-01-01

    A simulated household refrigerator was built that utilizes latent Thermal Energy Storage (TES) to reduce the on-off frequency of the compressor. It was found that the on-off frequency was reduced by a factor of six and that the energy consumption was less for a certain range of refrigerated space temperatures. A new evaporator design was used to accommodate the Phase Change Material (PCM). The evaporator consisted of four thin plates filled with PCM which were connected in parallel. The temperature distribution inside the PCM was also measured and the results are discussed. The PCM used was an aqueous solution of propylene glycol. In this paper freezing characteristics as well as some estimate of its latent heat are also discussed

  9. Pilot Testing of Commercial Refrigeration-Based Demand Response

    Energy Technology Data Exchange (ETDEWEB)

    Hirsch, Adam [National Renewable Energy Lab. (NREL), Golden, CO (United States); Clark, Jordan [National Renewable Energy Lab. (NREL), Golden, CO (United States); Deru, Michael [National Renewable Energy Lab. (NREL), Golden, CO (United States); Trenbath, Kim [National Renewable Energy Lab. (NREL), Golden, CO (United States); Doebber, Ian [National Renewable Energy Lab. (NREL), Golden, CO (United States); Studer, Daniel [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2015-10-08

    Supermarkets potentially offer a substantial demand response (DR) resource because of their high energy intensity and use patterns. This report describes a pilot project conducted to better estimate supermarket DR potential. Previous work has analyzed supermarket DR using heating, ventilating, and air conditioning (HVAC), lighting, and anti-condensate heaters. This project was concerned with evaluating DR using the refrigeration system and quantifying the DR potential inherent in supermarket refrigeration systems. Ancillary aims of the project were to identify practical barriers to the implementation of DR programs in supermarkets and to determine which high-level control strategies were most appropriate for achieving certain DR objectives. The scope of this project does not include detailed control strategy development for DR or development of a strategy for regional implementation of DR in supermarkets.

  10. Preservation by ionization of refrigerated vacuum-packed ground beef

    International Nuclear Information System (INIS)

    Soualhia, Z.

    1998-01-01

    The application of doses of 1, 2, 3, 4, 5 KGy is interesting to lower significantly the contamination microbial flora in ground beef without changing significantly for all that original qualities. Treatment combining ionization (5 KGy) and / or salting (2 %) increases of almost 2 months the duration of refrigerated conservation of Vacuum-packed ground beef with no major change in initial quality. In ionized beef (5 KGy) and / or salted (2 %), the rate of psychotropic germs stays inferior to the threshold superficial putrefaction at all conservation stages. Moreover, faecal contamination pilots, mouldiness, yeast and pathogenic micro-organisms are totally absent in treated samples. Reduction effect of salt is observed at all stages of refrigerated storage. Finally, after cooking, ionizing dose does not change significantly loss of weight and pH of ground beef heated at 100 degrees C in bain-marie or 150 degrees C in drying over during one hour (author)

  11. Magnetic refrigeration system with separated inlet and outlet flow

    Energy Technology Data Exchange (ETDEWEB)

    Auringer, Jon Jay; Boeder, Andre Michael; Chell, Jeremy Jonathan; Leonard, John Paul; Zimm, Carl Bruno

    2017-06-14

    An active magnetic regenerative (AMR) refrigerator apparatus can include at least one AMR bed with a first end and a second end and a first heat exchanger (HEX) with a first end and a second end. The AMR refrigerator can also include a first pipe that fluidly connects the first end of the first HEX to the first end of the AMR bed and a second pipe that fluidly connects the second end of the first HEX to the first end of the AMR bed. The first pipe can divide into two or more sub-passages at the AMR bed. The second pipe can divide into two or more sub-passages at the AMR bed. The sub-passages of the first pipe and the second pipe can interleave at the AMR bed.

  12. Combined cold compressor/ejector helium refrigerator cycle

    International Nuclear Information System (INIS)

    Schlafke, A.P.; Brown, D.P.; Wu, K.C.

    1984-01-01

    This chapter demonstrates how the use of a cold compressor in series with an ejector is an effective way to produce the desired low pressure in a helium refrigeration system. The cold compressor is tentatively located at the low pressure side below the J-T heat exchanger. The ejector is the first stage and the cold compressor is the second stage of the two-stage pumping system. A centrifugal, oil-bearing type compressor was installed on the R and D refrigerator at the Brookhaven National Laboratory. It is determined that the combined cold compressor and ejector system produces a lower temperature on the same load or more cooling at the same temperature compared with a system which uses an ejector alone. Results of the test showed a gain of 20%

  13. Cryogen-free dilution refrigerators

    International Nuclear Information System (INIS)

    Uhlig, K

    2012-01-01

    We review briefly our first cryogen-free dilution refrigerator (CF-DR) which was precooled by a GM cryocooler. We then show how today's dry DRs with pulse tube precooling have developed. A few examples of commercial DRs are explained and noteworthy features pointed out. Thereby we describe the general advantages of cryogen-free DRs, but also show where improvements are still desirable. At present, our dry DR has a base temperature of 10 mK and a cooling capacity of 700 μW at a mixing chamber temperature of 100 mK. In our cryostat, in most recent work, an additional refrigeration loop was added to the dilution circuit. This 4 He circuit has a lowest temperature of about 1 K and a refrigeration capacity of up to 100 mW at temperatures slightly above 1 K; the dilution circuit and the 4 He circuit can be run separately or together. The purpose of this additional loop is to increase the cooling capacity for experiments where the cooling power of the still of the DR is not sufficient to cool cold amplifiers and cables, e.g. in studies on superconducting quantum circuits or astrophysical applications.

  14. Cryogen-free dilution refrigerators

    Science.gov (United States)

    Uhlig, K.

    2012-12-01

    We review briefly our first cryogen-free dilution refrigerator (CF-DR) which was precooled by a GM cryocooler. We then show how today's dry DRs with pulse tube precooling have developed. A few examples of commercial DRs are explained and noteworthy features pointed out. Thereby we describe the general advantages of cryogen-free DRs, but also show where improvements are still desirable. At present, our dry DR has a base temperature of 10 mK and a cooling capacity of 700 μW at a mixing chamber temperature of 100 mK. In our cryostat, in most recent work, an additional refrigeration loop was added to the dilution circuit. This 4He circuit has a lowest temperature of about 1 K and a refrigeration capacity of up to 100 mW at temperatures slightly above 1 K; the dilution circuit and the 4He circuit can be run separately or together. The purpose of this additional loop is to increase the cooling capacity for experiments where the cooling power of the still of the DR is not sufficient to cool cold amplifiers and cables, e.g. in studies on superconducting quantum circuits or astrophysical applications.

  15. Superconducting tunnel-junction refrigerator

    International Nuclear Information System (INIS)

    Melton, R.G.; Paterson, J.L.; Kaplan, S.B.

    1980-01-01

    The dc current through an S 1 -S 2 tunnel junction, with Δ 2 greater than Δ 1 , when biased with eV 1 +Δ 2 , will lower the energy in S 1 . This energy reduction will be shared by the phonons and electrons. This device is shown to be analogous to a thermoelectric refrigerator with an effective Peltier coefficient π* approx. Δ 1 /e. Tunneling calculations yield the cooling power P/sub c/, the electrical power P/sub e/ supplied by the bias supply, and the cooling efficiency eta=P/sub c//P/sub e/. The maximum cooling power is obtained for eV= +- (Δ 2 -Δ 1 ) and t 1 =T 1 /T/sub c/1 approx. 0.9. Estimates are made of the temperature difference T 2 -T 1 achievable in Al-Pb and Sn-Pb junctions with an Al 2 O 3 tunneling barrier. The performance of this device is shown to yield a maximum cooling efficiency eta approx. = Δ 1 /(Δ 2 -Δ 1 ) which can be compared with that available in an ideal Carnot refrigerator of eta=T 1 /(T 2 -T 1 ). The development of a useful tunnel-junction refrigerator requires a tunneling barrier with an effective thermal conductance per unit area several orders of magnitude less than that provided by the A1 2 O 3 barrier in the Al-Pb and Sn-Pb systems

  16. Optimization analysis of the performance of an irreversible Ericsson refrigeration cycle in the micro/nanoscale

    International Nuclear Information System (INIS)

    Wang Hao; Wu Guoxing; Fu Yueming

    2011-01-01

    A general micro/nanoscaled model of the Ericsson refrigeration cycle is established in which finite-rate heat transfer, heat leak and regeneration time are taken into account. Based on the model, expressions for several important parameters such as the coefficient of performance (COP), cooling rate and power input are derived. By using numerical calculation and illustration, the influence of 'thermosize effects' on the performance of the Ericsson refrigeration cycle is discussed and evaluated. The optimal ranges of the COP, cooling rate and power input are determined. Furthermore, some special cases are discussed in detail. The results obtained here will provide theoretical guidance on designing a micro/nanoscaled Ericsson cycle device.

  17. Inter-cooler in solar-assisted refrigeration system: Theory and experimental verification

    Directory of Open Access Journals (Sweden)

    Zheng Hui-Fan

    2015-01-01

    Full Text Available An inter-cooler in the solar-assisted refrigeration system was investigated experimentally and theoretically, and the theoretical prediction was fairly in good agreement with the experimental data. The influence of pipe diameter, tooth depth, and spiral angle of inter-cooler on the performance of the refrigerant system was analyzed. It was concluded that heat transfer is influenced deeply by the structure parameters of inter-cooler, and the heat transfer capacity increases with tooth depth and spiral angle increasing, and decreases with tooth apex angle increasing.

  18. Functional Dependence of Thermodynamic and Thermokinetic Parameters of Refrigerants Used in Mine Air Refrigerators. Part 1 - Refrigerant R407C

    Science.gov (United States)

    Nowak, Bernard; Życzkowski, Piotr; Łuczak, Rafał

    2017-03-01

    The authors of this article dealt with the issue of modeling the thermodynamic and thermokinetic properties (parameters) of refrigerants. The knowledge of these parameters is essential to design refrigeration equipment, to perform their energy efficiency analysis, or to compare the efficiency of air refrigerators using different refrigerants. One of the refrigerants used in mine air compression refrigerators is R407C. For this refrigerant, 23 dependencies were developed, determining its thermodynamic and thermokinetic parameters in the states of saturated liquid, dry saturated vapour, superheated vapor, subcooled liquid, and in the two-phase region. The created formulas have been presented in Tables 2, 5, 8, 10 and 12, respectively. It should be noted that the scope of application of these formulas is wider than the range of changes of that refrigerant during the normal operation of mine refrigeration equipment. The article ends with the statistical verification of the developed dependencies. For this purpose, for each model correlation coefficients and coefficients of determination were calculated, as well as absolute and relative deviations between the given values from the program REFPROP 7 (Lemmon et al., 2002) and the calculated ones. The results of these calculations have been contained in Tables 14 and 15.

  19. 10 CFR 431.62 - Definitions concerning commercial refrigerators, freezers and refrigerator-freezers.

    Science.gov (United States)

    2010-01-01

    ... functional characteristics that affect energy consumption. Commercial refrigerator, freezer, and refrigerator... formed by the plane of the door, when the equipment is viewed in cross-section; and (2) For equipment...

  20. Optimum analysis of a Brownian refrigerator.

    Science.gov (United States)

    Luo, X G; Liu, N; He, J Z

    2013-02-01

    A Brownian refrigerator with the cold and hot reservoirs alternating along a space coordinate is established. The heat flux couples with the movement of the Brownian particles due to an external force in the spatially asymmetric but periodic potential. After using the Arrhenius factor to describe the behaviors of the forward and backward jumps of the particles, the expressions for coefficient of performance (COP) and cooling rate are derived analytically. Then, through maximizing the product of conversion efficiency and heat flux flowing out, a new upper bound only depending on the temperature ratio of the cold and hot reservoirs is found numerically in the reversible situation, and it is a little larger than the so-called Curzon and Ahlborn COP ε(CA)=(1/√[1-τ])-1. After considering the irreversible factor owing to the kinetic energy change of the moving particles, we find the optimized COP is smaller than ε(CA) and the external force even does negative work on the Brownian particles when they jump from a cold to hot reservoir.

  1. HeREF-2003: Helium Refrigeration Techniques

    CERN Multimedia

    2003-01-01

    CERN Technical Training 2003: Learning for the LHC ! Theory, Technology, Maintenance and Control of Helium Refrigerators HeREF-2003 is a course in the framework of the 2002 Technical Training Programme, that will provide a complete introduction to Helium refrigeration, with a practical approach to theory, technology, maintenance and control of Helium refrigeration installations. Theoretical aspects and equations will be limited to a minimum. HeREF-2003 targets an audience of technicians and operators of Helium refrigeration plants at CERN, as well as physicists and engineers needing an overview of current Helium refrigeration techniques. HeREF-2003 will address, among other, issues related to component technology, installation maintenance, process control and Helium purity. A commented visit to a couple of CERN Helium refrigeration or liquefaction plants will also take place. Duration: 7 half days (4 mornings and 3 afternoons), 6-10 October, 2003 Cost per participant: 500.- CHF Language: Bilingual English...

  2. HeREF-2003 : Helium Refrigeration Techniques

    CERN Multimedia

    2003-01-01

    CERN Technical Training 2003: Learning for the LHC ! Theory, Technology, Maintenance and Control of Helium Refrigerators HeREF-2003 is a course in the framework of the 2002 Technical Training Programme, that will provide a complete introduction to Helium refrigeration, with a practical approach to theory, technology, maintenance and control of Helium refrigeration installations. Theoretical aspects and equations will be limited to a minimum. HeREF-2003 targets an audience of technicians and operators of Helium refrigeration plants at CERN, as well as physicists and engineers needing an overview of current Helium refrigeration techniques. HeREF-2003 will address, among other, issues related to component technology, installation maintenance, process control and Helium purity. A commented visit to a couple of CERN Helium refrigeration or liquefaction plants will also take place. • Duration: 7 half days (4 mornings and 3 afternoons), 6-10 October, 2003 • Cost per participant: 500.- CHF ...

  3. Optimum operating regimes of common paramagnetic refrigerants

    CERN Document Server

    Wikus, P; Figueroa-Feliciano, E

    2011-01-01

    Adiabatic Demagnetization Refrigerators (ADRs) are commonly used in cryogenic laboratories to achieve subkelvin temperatures. ADRs are also the technology of choice for several space borne instruments which make use of cryogenic microcalorimeters or bolometers {[}1-4]. For these applications, refrigerants with high ratios of cooling capacity to volume, or cooling capacity to mass are usually required. In this manuscript, two charts for the simple selection of the most suitable of several common refrigerants (CAA, CMN, CPA, DGG, FAA, GGG, GLF and MAS) are presented. These graphs are valid for single stage cycles. The selection of the refrigerants is uniquely dependent on the starting conditions of the refrigeration cycle (temperature and magnetic field density) and the desired final temperature. Only thermodynamic properties of the refrigerants have been taken into account, and other important factors such as availability and manufacturability have not been considered. (C) 2011 Elsevier Ltd. All rights reserve...

  4. Optimization of a solar driven absorption refrigerator in the transient regime

    International Nuclear Information System (INIS)

    Hamed, Mouna; Fellah, Ali; Ben Brahim, Ammar

    2012-01-01

    Highlights: ► Dynamic behavior of a solar absorption refrigerator endoreversible model. ► Using the principles of classical thermodynamics, mass and heat transfers. ► Minimizing heat exchange time to reach maximum performances. ► Major influence of the collector temperature on the model’s characteristics. ► Analogous effects of both the thermal load and the thermal conductance. -- Abstract: This contribution deals with the theoretical study in dynamic mode of an absorption refrigerator endoreversible model. The system is a cold generating station driven by solar energy. The main elements of the cycle are a refrigerated space, an absorption refrigerator and a solar collector form. A mathematical model is developed. It combines the classical thermodynamics and mass and heat transfers principles. The numerical simulation is made for different operating and conceptual conditions. A global minimizing time optimization is performed in view to reach maximum performances. Appropriate dimensionless groups are defined. The results are presented in normalized charts for general applications. The collector temperature presents major influence on the conceptual and functional characteristics compared to the stagnation temperature influence. On the other hand the thermal load in the refrigerated space and the thermal conductance of the walls has analogous effects, therefore important to be considered in actual design. As a result, the model is expected to be a useful tool for simulation, design, and optimization of solar collector based energy systems.

  5. State-space modelling for the ejector-based refrigeration system driven by low grade energy

    International Nuclear Information System (INIS)

    Xue, Binqiang; Cai, Wenjian; Wang, Xinli

    2015-01-01

    This paper presents a novel global state-space model to describe the ejector-based refrigeration system, which includes the dynamics of the two heat exchangers and the static properties of ejector, compressor and expansion valve. Different from the existing methods, the proposed method introduces some intermediate variables into the dynamic modelling in developing reduced order models of the heat exchangers (evaporator and condenser) based on the Number of Transfer Units (NTU) method. This global model with fewer dimensions is much simpler and can be more convenient for the real-time control system design, compared with other dynamic models. Finally, the proposed state-space model has been validated by dynamic response experiments on the ejector-based refrigeration cycle with refrigerant R134a.The experimental results indicate that the proposed model can predict well the dynamics of the ejector-based refrigeration system. - Highlights: • A low-order state-space model of ejector-based refrigeration system is presented. • Reduced-order models of heat exchangers are developed based on NTU method. • The variations of mass flow rates are introduced in multiple fluid phase regions. • Experimental results show the proposed model has a good performance

  6. CFD simulations and reduced order modeling of a refrigerator compartment including radiation effects

    International Nuclear Information System (INIS)

    Bayer, Ozgur; Oskay, Ruknettin; Paksoy, Akin; Aradag, Selin

    2013-01-01

    Highlights: ► Free convection in a refrigerator is simulated including radiation effects. ► Heat rates are affected drastically when radiation effects are considered. ► 95% of the flow energy can be represented by using one spatial POD mode. - Abstract: Considering the engineering problem of natural convection in domestic refrigerator applications, this study aims to simulate the fluid flow and temperature distribution in a single commercial refrigerator compartment by using the experimentally determined temperature values as the specified constant wall temperature boundary conditions. The free convection in refrigerator applications is evaluated as a three-dimensional (3D), turbulent, transient and coupled non-linear flow problem. Radiation heat transfer mode is also included in the analysis. According to the results, taking radiation effects into consideration does not change the temperature distribution inside the refrigerator significantly; however the heat rates are affected drastically. The flow inside the compartment is further analyzed with a reduced order modeling method called Proper Orthogonal Decomposition (POD) and the energy contents of several spatial and temporal modes that exist in the flow are examined. The results show that approximately 95% of all the flow energy can be represented by only using one spatial mode

  7. Evaluation of Virtual Refrigerant Mass Flow Sensors

    OpenAIRE

    Kim, Woohyun; Braun, James E.

    2012-01-01

    Refrigerant mass flow rate is an important measurement for monitoring equipment performance and enabling fault detection and diagnostics. However, a traditional mass flow meter is expensive to purchase and install. A virtual refrigerant mass flow sensor (VRMF) uses a mathematical model to estimate flow rate using low-cost measurements and can potentially be implemented at low cost. This study evaluates three VRMFs for estimating refrigerant mass flow rate. The first model uses a compressor ma...

  8. Adsorption refrigeration technology theory and application

    CERN Document Server

    Wang, Ruzhu; Wu, Jingyi

    2014-01-01

    Gives readers a detailed understanding of adsorption refrigeration technology, with a focus on practical applications and environmental concerns Systematically covering the technology of adsorption refrigeration, this book provides readers with a technical understanding of the topic as well as detailed information on the state-of-the-art from leading researchers in the field. Introducing readers to background on the development of adsorption refrigeration, the authors also cover the development of adsorbents, various thermodynamic theories, the design of adsorption systems and adsorption refri

  9. Performance Optimization of Alternative Lower Global Warming Potential Refrigerants in Mini-Split Room Air Conditioners

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Bo [ORNL; Abdelaziz, Omar [ORNL; Shrestha, Som S [ORNL

    2017-01-01

    Oak Ridge National laboratory (ORNL) recently conducted extensive laboratory, drop-in investigations for lower Global Warming Potential (GWP) refrigerants to replace R-22 and R-410A. ORNL studied propane, DR-3, ARM-20B, N-20B and R-444B as lower GWP refrigerant replacement for R-22 in a mini-split room air conditioner (RAC) originally designed for R-22; and, R-32, DR-55, ARM-71A, and L41-2, in a mini-split RAC designed for R-410A. We obtained laboratory testing results with very good energy balance and nominal measurement uncertainty. Drop-in studies are not enough to judge the overall performance of the alternative refrigerants since their thermodynamic and transport properties might favor different heat exchanger configurations, e.g. cross-flow, counter flow, etc. This study compares optimized performances of individual refrigerants using a physics-based system model tools. The DOE/ORNL Heat Pump Design Model (HPDM) was used to model the mini-split RACs by inputting detailed heat exchangers geometries, compressor displacement and efficiencies as well as other relevant system components. The RAC models were calibrated against the lab data for each individual refrigerant. The calibrated models were then used to conduct a design optimization for the cooling performance by varying the compressor displacement to match the required capacity, and changing the number of circuits, refrigerant flow direction, tube diameters, air flow rates in the condenser and evaporator at 100% and 50% cooling capacities. This paper compares the optimized performance results for all alternative refrigerants and highlights best candidates for R-22 and R-410A replacement.

  10. Investigation on an innovative cascading cycle for power and refrigeration cogeneration

    International Nuclear Information System (INIS)

    Jiang, Long; Lu, Huitong; Wang, Ruzhu; Wang, Liwei; Gong, Lixia; Lu, Yiji; Roskilly, Anthony Paul

    2017-01-01

    Highlights: • A novel cascading cycle for power and refrigeration cogeneration is proposed and investigated. • Pumpless ORC and sorption refrigeration cycle act as the first and second stage. • The highest power and refrigeration output are able to reach 232 W and 4.94 kW, respectively. • The exergy efficiency of heat utilization ranges from 30.1% to 41.8%. - Abstract: In order to further realize efficient utilization of low grade heat, an innovative cascading cycle for power and refrigeration cogeneration is proposed. Pumpless Organic Rankine Cycle (ORC) acts as the first stage, and the refrigerant R245fa is selected as the working fluid. Sorption refrigeration cycle serves as the second stage in which silica-gel/LiCl composite sorbent is developed for the improved sorption characteristic. The concerning experimental system is established, and different hot water inlet temperatures from 75 °C to 95 °C are adopted to investigate the cogeneration performance. It is indicated that the highest power and refrigeration output are able to reach 232 W and 4.94 kW, respectively under the condition of 95 °C hot water inlet temperature, 25 °C cooling water temperature and 10 °C chilled water outlet temperature. For different working conditions, the total energy and exergy efficiency of the cascading system range from 0.236 to 0.277 and 0.101 to 0.132, respectively. For cascading system the exergy efficiency of heat utilization ranges from 30.1% to 41.8%, which is 144% and 60% higher than that of pumpless ORC and sorption chiller when the hot water inlet temperature is 95 °C.

  11. Know-how of refrigerating technology. 2. completely rev. ed. Fachwissen Kaeltetechnik fuer die industrielle und gewerbliche Praxis; Eine Einfuehrung mit Aufgaben und Loesungen

    Energy Technology Data Exchange (ETDEWEB)

    Reisner, K.

    1994-01-01

    This specialized book is based on causes on refrigerating technology held in preparation of apprentices and master candidates for their examinations and on training seminars for operators and users. It bebins with a generalised presentation intended to enable the constructor of a plant to develop an initial concept. The author then explains step by step from the basics of thermodynamics over to fluid mechanics the entire spectrum of subdisciplines that make up refrigerating technology: cooling circuit, compression refrigerants, heat exchange, regulators, piping, required cooling capacity. Practice-oriented calculation models for all fields of refrigerating technology also make the work a valuable reference book. (BWI)

  12. United States: refrigeration industry blows hot

    International Nuclear Information System (INIS)

    Crawford, J.

    1997-01-01

    In the framework of the Kyoto convention on global warming, the american refrigeration industries have undertaken several organizations and contacts with governments and agencies in order to explain the real issues concerning the effects of refrigerant utilization in refrigerating machines on the greenhouse effect, taking into consideration the commercial impact that a ban on certain refrigerants could have on the industry's business. They argue that HFC utilization in this industry is fundamentally non-emissive and that important improvements have been realized concerning tightness and energy consumption

  13. Rotary magnetic refrigerator for superfluid helium production

    International Nuclear Information System (INIS)

    Hakuraku, Y.; Ogata, H.

    1986-01-01

    A new rotary-magnetic refrigerator designed to obtain superfluid helium temperatures by executing a magnetic Carnot cycle is developed. A rotor containing 12 magnetic refrigerants (gadolinium-gallium-garnet) is immersed in liquid helium at 4.2 K and rotated at constant speed in a steady magnetic field distribution. Performance tests demonstrate that the new rotary refrigerator is capable of obtaining a temperature of 1.48 K. The maximum useful cooling power obtained at 1.8 K is 1.81 W which corresponds to a refrigeration efficiency of 34%

  14. Global patterns of land-atmosphere fluxes of carbon dioxide, latent heat, and sensible heat derived from eddy covariance, satellite, and meteorological observations

    Science.gov (United States)

    Martin, J.; Reichstein, M.

    2012-12-01

    We upscaled FLUXNET observations of carbon dioxide, water and energy fluxes to the global scale using the machine learning technique, Model Tree Ensembles (MTE). We trained MTE to predict site-level gross primary productivity (GPP), terrestrial ecosystem respiration (TER), net ecosystem exchange (NEE), latent energy (LE), and sensible heat (H) based on remote sensing indices, climate and meteorological data, and information on land use. We applied the trained MTEs to generate global flux fields at a 0.5° x 0.5o spatial resolution and a monthly temporal resolution from 1982-2008. Cross-validation analyses revealed good performance of MTE in predicting among-site flux variability with modeling efficiencies (MEf) between 0.64 and 0.84, except for NEE (MEf = 0.32). Performance was also good for predicting seasonal patterns (MEf between 0.84 and 0.89, except for NEE (0.64)). By comparison, predictions of monthly anomalies were weak. Our products are increasingly used to evaluate global land surface models. However, depending on the flux of interest (e.g. gross primary production, terrestrial ecosystem respiration, net ecosystem exchange, evapotranspiration) and the pattern of interest (mean annual map, seasonal cycles, interannual variability, trends) the robustness and uncertainty of these products varies considerably. To avoid pitfalls, this talk also aims at providing an overview of uncertainties associated with these products, and to provide recommendations on the usage for land surface model evaluations. Finally, we present FLUXCOM - an ongoing activity that aims at generating an ensemble of data-driven FLUXNET based products based on diverse approaches.

  15. Evaporation of new refrigerants on tube with improved surfaces. Final report. Appendices: A, B, C, D, E and F; Evaporation de nouveaux refrigerants sur des tubes a surface amelioree. Rapport final. Annexes: A, B, C, D, E et F

    Energy Technology Data Exchange (ETDEWEB)

    Kattan, N.; Favrat, D.; Thome, J. R.; Nidegger, E.; Zuercher, O. [Ecole Polytechnique Federale, Lab. d` Energetique Industrielle (LENI), Lausanne (Switzerland)

    1995-07-15

    The substitution of old refrigerants in refrigeration systems, heat pumps and organic Rankine cycles for heat recovery, request a good knowledge of heat transfer properties of substitute fluids. The test measurements in LENI test facility (concentric tubes with water flowing in a counter-current flow) with new refrigerants like HFC134a, HCFC123, R-402A, have established a new data bank with new refrigerants, a comparison with old refrigerants like CFC11, CFC12 CFC/HCFC502 and with existent correlations. Correlations were programmed to calculate and compare heat transfer coefficient during the tests. To develop a new correlation based on flow regimes, a high speed Sony video tape camera is used to observe and identify flow patterns. Important images are captured, digitalized, stored for later analysis and sent to a color plotter. Several flow pattern maps were programmed and compared to flow regimes observed on the test rig. Local flow boiling heat transfer coefficients were measured for HFC134a and HCFC123 evaporating inside a microfin tube. In addition, microheat transfer augmentation relative to plain tube test data was investigated. The presence of oil in the evaporator has an effect on heat transfer coefficient. Local flow boiling heat transfer coefficients were measured for refrigerant HFC134a-oil ester (Mobil EAL Arctic 68). A new thermodynamic approach for modeling mixtures of refrigerants and lubricating oils is developed. A very high accuracy, straight vibrating tube type of density flowmeter is used to measure oil concentrations of flowing HFC134a-oil mixtures. (author) figs., tabs., refs.

  16. Performance and energy saving analysis of a refrigerator using hydrocarbon mixture (HC-R134a) as working fluid

    Science.gov (United States)

    Mohtar, M. N.; Nasution, H.; Aziz, A. A.

    2015-12-01

    The use of hydrocarbon mixture as a working fluid in a refrigerator system is rarely explored. Almost all domestic refrigerators use hydroflourocarbon R134a (HFC-R134a) as refrigerants. In this study, hydrocarbon gas (HC-R134a) is used as the alternative refrigerant to replace HFC-R134a. It has a composition of R290 (56%), R600a (54.39%) and additive (0.1%wt) blended for the trials. The experiments were conducted with 105 g and 52.5 g refrigerant mass charge, subjected to internal heat load of 0, 1, 2, 3 and 4 kg respectively. The study investigates the coefficient of performance of the refrigerator (COPR) and energy consumption. The results show that the use of HC-R134a as the replaceable refrigerant can save energy ranging from 2.04% to 7.09%, as compared to the conventional HFC-R134a refrigerant. Naturally, the COPR improvement and temperature distribution using HC-R134a are much better than HFC-R134a

  17. Development of a two-phase, two-component jet pump refrigerator for utilization of low-temperature solar heat. Final report; Entwicklung einer Zweiphasen-/Zweikomponenten-Strahlpumpenkaelteanlage zur Nutzung solarer Niedertemperaturwaerme. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Mostofizadeh, C.; Bohne, D.

    2001-08-01

    A solar refrigerator for air conditioning and cooling was developed. The key component is a two-phase, two-component jet pump with ammonia and water as working fluid. Both the pump flow and the suction flow can be two-phase flows. This way, the advantages of both the absorption and the compression principle will be utilized, and a compact size will be achieved. Upon termination of the calculations, the function of the pump will be investigated in a 0 W pilot plant. For this, various geometries were calculated and tested for their potential efficiencies. A prototype will be constructed on the basis of the results. [German] Das Ziel des Vorhabens besteht in der Entwicklung einer solarbetriebenen Kaelteanlage fuer Klimatisierungs- und Kuehlungszwecke. Die Hauptkomponente der Kaelteanlage ist eine Zweiphasen-/Zweikomponenten-Strahlpumpe, die mit dem Arbeitsgemisch Ammoniak/Wasser betrieben wird. Sowohl der Treib- als auch der Saugstrom koennen zweiphasig sein. Dadurch sollen einerseits die Vorteile des Absorptions- und des Kompressionsprinzips miteinander verknuepft und andererseits ein kompakter Aufbau erreicht werden. Nach Abschluss der thermodynamischen und kinetischen Berechnungen soll die Funktion der Zweiphasen-/Zweikomponenten-Strahlpumpe mit Hilfe einer Pilotanlage mit ca. 20 kW Kaelteleistung untersucht werden. Dazu werden nach Vorausberechnungen verschiedene Geometrien in Bezug auf erzielbare Wirkungsgrade getestet. Die Ergebnisse bilden die Basis fuer den Bau eines Prototyps. (orig.)

  18. Electric heat pump for motor vehicles with R744 (CO{sub 2}) as refrigerant; Elektrisch betriebene Waermepumpe fuer Fahrzeuge mit dem Kaeltemittel R744 (CO{sub 2})

    Energy Technology Data Exchange (ETDEWEB)

    Huenemoerder, W.; Kakehashi, N. [DENSO Automotive Deutschland GmbH, Eching (Germany)

    2003-07-01

    R744 (carbon dioxide) is suited for low ambient temperatures. A motor car air conditioner on this basis was developed for engines with low heat emissions. The passenger compartment is heated and cooled by a single system comprising a semihermetic electric compressor and three air-filled heat transfer units, i.e. an evaporator and a gas cooler for heating inside the car and a heat exchanger on the outside which can serve as evaporator or gas cooler as desired. The system can be operated in four modes: Heating without dehumidification, heating and dehumidification, cooling, thawing of the external heat exchanger. In contrast to conventional systems, the heating and cooling mode are not independent of each other, so a special control concept was developed which enables automatic operation of the four above modes of operation. The system is used in the Toyota FCHV fuel cell car. (orig.) [German] Das Kaeltemittel CO{sub 2} (R744) kann auch bei niederen Umgebungstemperaturen fuer Waermepumpenanwendungen eingesetzt werden. Eine CO{sub 2}-Klimaanlage mit Waermepumpe wurde fuer die Klimatisierung (Heizen, Kuehlen und Entfeuchten) des Fahrzeuginnenraumes entwickelt. Diese Anlage ist fuer Elektro- und Breenstoffzellenfahrzeuge geeignet, bei denen keine Motorabwaerme zu Heizzwecken zur Verfuegung steht. Heizen und Kuehlen des Innenraumes erfolgt durch ein einziges System unter Verwendung derselben Komponenten. Die Anlage besteht aus einem halbhermetischen elektrischen Verdichter und drei luftbeaufschlagten Waermeuebertragern - ein Verdampfer und ein Gaskuehler (zum Heizen) im Innenraum und ein Waermeuebertrager aussen, der - je nach Betriebsart - als Verdampfer oder Gaskuehler betrieben wird. Die Anlage kann in vier Betriebsarten betrieben werden: Heizen ohne Entfeuchtung, Heizen mit Entfeuchtung, Kuehlen, Abtauen des aeusseren Waermeuebertragers. In konventionellen Systemen koennen Heiz- und Kuehlsystem unabhaengig voneinander geregelt werden. Bei dem hier vorgestellten

  19. RECENT PROGRESS IN DYNAMIC PROCESS SIMULATION OF CRYOGENIC REFRIGERATORS

    International Nuclear Information System (INIS)

    Kuendig, A.

    2008-01-01

    At the CEC 2005 a paper with the title ''Helium refrigerator design for pulsed heat load in Tokamaks'' was presented. That paper highlighted the control requirements for cryogenic refrigerators to cope with the expected load variations of future nuclear fusion reactors. First dynamic computer simulations have been presented.In the mean time, the computer program is enhanced and a new series of process simulations are available. The new program considers not only the heat flows and the temperature variations within the heat exchangers, but also the variation of mass flows and pressure drops. The heat transfer numbers now are calculated in dependence of the flow speed and the gas properties. PI-controllers calculate the necessary position of specific valves for maintaining pressures, temperatures and the rotation speed of turbines.Still unsatisfactory is the fact, that changes in the process arrangement usually are attended by adjustments in the program code. It is the main objective of the next step of development a more flexible code which enables that any user defined process arrangements can be assembled by input data

  20. Investigation of two-phase thermosyphon performance filled with modern HFC refrigerants

    Science.gov (United States)

    Gorecki, Grzegorz

    2018-02-01

    Two-phase closed thermosyphons (TPCTs) are widely utilized as heat exchanger elements in waste heat recovery systems and as passive heating/cooling devices. They are popular because of their high thermal conductivity, simple construction and reliability. Previous researches indicate that refrigerants are performing better than typical TPCT working fluids like deionized water or alcohols in the low temperature range. In the present study three HFC (Hydrofluorocarbons) refrigerants were tested: R134a, R404A and R407C. The total length of the investigated TPCT is 550 mm with equal length (245 mm) condenser and evaporator sections. Its outer diameter is 22 mm with 1 mm wall thickness. The evaporator section was heated by hot water with varying inlet temperature by 5 K step in the range of 288 K - 323 K. The condenser was cooled by cold water with inlet temperature kept at a constant value of 283 K. It was found that using R134a and R404A as working fluids heat transfer rates are the highest. For both refrigerants 10% is optimal filling ratio. They can be utilized interchangeably because the differences between their throughputs are within uncertainty bands. R407C performance was 50% lower. Other disadvantages of using this refrigerant are relatively high working pressures and higher optimal filling ratio (30%).