ESO2 Optimization of Supermarket Refrigeration Systems

DEFF Research Database (Denmark)

Petersen, Lars Norbert; Madsen, Henrik; Heerup, Christian

Supermarket refrigeration systems consists of a number of display cases, cooling cabinets and cold rooms connected to a central compressor pack. This configuration saves energy compared to placing a compressor at each cooling site. The classical control setup of a supermarket refrigeration system...... in the supermarket. The first approach to solve this problem is to design an overall control system which coordinates the compressor capacity and the current refrigeration load. The drawback of this approach is the complexity of the single controller. The solution is investigated in the first part of the report...

Experimental results of a direct air-cooled ammonia–lithium nitrate absorption refrigeration system

International Nuclear Information System (INIS)

Llamas-Guillén, S.U.; Cuevas, R.; Best, R.; Gómez, V.H.

2014-01-01

Absorption thermal cooling systems driven by renewable energy are a viable option in order to reduce fossil fuel consumption and the associated emissions. This work shows the results of an air cooled absorption cooling prototype working with an ammonia–lithium nitrate mixture at high ambient temperatures. An absorption refrigeration system was designed and built. The prototype is a one stage ammonia–lithium nitrate air cooled chiller. The experimental system was instrumented to evaluate each component. This paper shows the operation conditions in the experimental unit as well as some of the heat loads encountered at different operating conditions. The system was operated successfully at ambient temperatures in the range of 25–35 °C. A series of test showed that even at ambient temperatures it can be operated at evaporator temperatures below 10 °C producing chilled water for air conditioning applications such as radiative cooling panels. The system proved to stabilize very quickly and no risk of crystallization was encountered so the first results are promising in order to continue with the development of a more advanced prototype. - Highlights: •Experimental results of a direct air-cooled ammonia–lithium nitrate system. •The prototype is a one stage ammonia–lithium nitrate air cooled chiller. •The absorption system was operated successfully at ambient temperatures. •Cooling loads of 4.5 kW were reached in the chilled water side

Cooling transfer fluids: advantages, drawbacks, refrigerant circuit architecture; Les fluides frigoporteurs: avantages, inconvenients, apercu sur l`architecture des circuits frigoporteurs

Energy Technology Data Exchange (ETDEWEB)

Duminil, M. [Association Francaise du Froid (AFF), 75 - Paris (France)

1997-12-31

The advantages and inconvenients of indirect cooling systems are summarized: simplification of the cooling distribution from a single refrigerating unit, a potential for a larger range of refrigerants, cooling circuit size diminution, but energy consumption increase, lower evaporation temperature, etc. The various types and characteristics of single- and two-phase refrigerant and heat transfer fluids are described, and more especially two-phase liquid-vapour and liquid-solid fluids. Based on the example of a two-temperature-level refrigerating system in a supermarket, the general architecture of the cold distribution circuit and the architecture of the refrigerant circuit itself, are presented with their different types, involving direct or indirect, and centralized or semi-centralized systems

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

Performance analysis for minimally nonlinear irreversible refrigerators at finite cooling power

Science.gov (United States)

Long, Rui; Liu, Zhichun; Liu, Wei

2018-04-01

The coefficient of performance (COP) for general refrigerators at finite cooling power have been systematically researched through the minimally nonlinear irreversible model, and its lower and upper bounds in different operating regions have been proposed. Under the tight coupling conditions, we have calculated the universal COP bounds under the χ figure of merit in different operating regions. When the refrigerator operates in the region with lower external flux, we obtained the general bounds (0 present large values, compared to a relative small loss from the maximum cooling power. If the cooling power is the main objective, it is desirable to operate the refrigerator at a slightly lower cooling power than at the maximum one, where a small loss in the cooling power induces a much larger COP enhancement.

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

Application of Cascade Refrigeration System with Mixing Refrigerant in Cold Air Cutting

Science.gov (United States)

Yang, Y.; Tong, M. W.; Yang, G.; Wang, X. P.

In the mechanical cutting process, the replacement of traditional cutting solution with cold air can avoid the pollution of environment. In order to high efficient the refrigerating device and flexible adjust the temperature of cold air, it is necessary to use cascade refrigeration system to supply cool quantity for the compressed air. The introduction of a two-component non-azeotropic mixing refrigerant into the cryogenic part of the cascade system, can effectively solve the problems of the system working at too high pressure and the volume expanding of refrigerant in case of the cascade refrigeration sets closed down. However, the filling ratio of mixing refrigerants impact on the relationships among the closing down pressure, refrigerating output and refrigerating efficiency. On the basis of computing and experiment, the optimal mixing ratio of refrigerant R22/R13 and a low temperature of -60° were obtained in this study. A cold air injecting device possessing high efficiency in energy saving has also been designed and manufactured. The cold air, generated from this cascade system and employed in a cutting process, takes good comprehensive effects on machining and cutting.

Energy consumption of cooling systems. Optimization of the energy consumption of the cooling system in electric refrigerators; Energiforbrug i koelesystemer. Optimering af energiforbruget i koelesystemer i eldrevne koeleskabe

Energy Technology Data Exchange (ETDEWEB)

Danig, P.O. [Danmarks Tekniske Universitet (Denmark); Pedersen, J.K.; Ritchie, E. [Aalborg Universitet (Denmark); Kierkegaard, P. [CETEC E/F (Denmark)

1997-12-31

The aim of the project was to determine an energy optimum solution for household refrigerators comprising the whole system from electric power supply to the cooled food. The basic idea was to replace the normal ON/OFF control with continuous operation, but so that the engine`s speed of rotation and thereby the performance of the compressor should be controlled according to the cooling demand. A 325 l Gram refrigerator model KS350 was used in the experiments and as a reference. In conventional operation - with a 3,13 cm{sup 3} compressor using ON/OFF control - this refrigerator on average used 33 W at the ISO point (ISO 7371 standard). The most important technical results are that continuous operation of refrigerators uses substantial less energy than ON/OFF control, and that this mode of operation improves the quality of the stored food. A compressor which is small enough to even a refrigerator of the size of 325 l does not exist on the market. A new compressor type must therefore be developed which must by combined and optimized with a pinion. A new compressor type with pinion will, when developed, demand substantial production changes at costs of probably a three-figure million amount. There is no doubt that the continuous operation of refrigerators will become dominating in the future, and globally it will result in a decrease of the energy consumption of 2-3%. (LN)

Cooling system for superconducting magnet

Science.gov (United States)

Gamble, Bruce B.; Sidi-Yekhlef, Ahmed

1998-01-01

A cooling system is configured to control the flow of a refrigerant by controlling the rate at which the refrigerant is heated, thereby providing an efficient and reliable approach to cooling a load (e.g., magnets, rotors). The cooling system includes a conduit circuit connected to the load and within which a refrigerant circulates; a heat exchanger, connected within the conduit circuit and disposed remotely from the load; a first and a second reservoir, each connected within the conduit, each holding at least a portion of the refrigerant; a heater configured to independently heat the first and second reservoirs. In a first mode, the heater heats the first reservoir, thereby causing the refrigerant to flow from the first reservoir through the load and heat exchanger, via the conduit circuit and into the second reservoir. In a second mode, the heater heats the second reservoir to cause the refrigerant to flow from the second reservoir through the load and heat exchanger via the conduit circuit and into the first reservoir.

Thermodynamic analysis of a novel ejector expansion transcritical CO_2/N_2O cascade refrigeration (NEETCR) system for cooling applications at low temperatures

International Nuclear Information System (INIS)

Megdouli, K.; Ejemni, N.; Nahdi, E.; Mhimid, A.; Kairouani, L.

2017-01-01

Natural substances are becoming very promising for long term alternative for refrigeration purposes. In this paper, two natural refrigerants have been proposed and analyzed for a novel ejector expansion transcritical cascade refrigeration (NEETCR) system. Nitrous oxide (N_2O) is used in the low temperature circuit (LTC) whereas carbon dioxide (CO_2) is used in the high temperature circuit (HTC) of the NEETCR system. The reject of refrigerant vapor heat in the HTC is carried out through the use of transcritical carbon dioxide Rankine cycle. This produces work, which will be used to reduce the consumption work of compressors and feed pump thereby resulting in the improvement of the energy efficiency of the whole system. The simulation results were obtained by a computer FORTRAN program, where REFPROP 9 database was used to get the refrigerant thermodynamic properties. The simulation results showed that the (NEETCR) system had higher coefficient of performance and higher system second law efficiency compared to the EETCR system. An enhancement more than 9% in the COP and exergy efficiency of NEETCR system was found in comparison with EETCR system, when the cooling capacity and operating conditions of the two systems were the same. The increase of COP of NEETCR system and its efficiency along with the reduction of power consumption make it more practical for the use in cooling applications. - Highlights: • Exergy-energy analysis of two cascade refrigeration systems is conducted. • The input power of the NEETCR system is lower than that of the EETCR system. • The COP of the NEETCR system is higher than that of the EETCR system. • The NEETCR system is promise in cascade refrigeration system.

Adopted Methodology for Cool-Down of SST-1 Superconducting Magnet System: Operational Experience with the Helium Refrigerator

Science.gov (United States)

Sahu, A. K.; Sarkar, B.; Panchal, P.; Tank, J.; Bhattacharya, R.; Panchal, R.; Tanna, V. L.; Patel, R.; Shukla, P.; Patel, J. C.; Singh, M.; Sonara, D.; Sharma, R.; Duggar, R.; Saxena, Y. C.

2008-03-01

The 1.3 kW at 4.5 K helium refrigerator / liquefier (HRL) was commissioned during the year 2003. The HRL was operated with its different modes as per the functional requirements of the experiments. The superconducting magnets system (SCMS) of SST-1 was successfully cooled down to 4.5 K. The actual loads were different from the originally predicted boundary conditions and an adjustment in the thermodynamic balance of the refrigerator was necessary. This led to enhanced capacity, which was achieved without any additional hardware. The required control system for the HRL was tuned to achieve the stable thermodynamic balance, while keeping the turbines' operating parameters at optimized conditions. An extra mass flow rate requirement was met by exploiting the margin available with the compressor station. The methodology adopted to modify the capacity of the HRL, the safety precautions and experience of SCMS cool down to 4.5 K, are discussed.

Comparative performance analysis of ice plant test rig with TiO2-R-134a nano refrigerant and evaporative cooled condenser

Directory of Open Access Journals (Sweden)

Amrat Kumar Dhamneya

2018-03-01

Full Text Available The nanoparticle is used in chillers for increasing system performance. The increasing concentration of nanoparticles (TiO2 in refrigerant increases the performances of the system due decreasing compressor work done and enhance heat transfer rate. For hot and dry climate condition, performances of air-cooled condenser minimize, and C. O. P. decreases extensively in chillers due to heat transfer rate decreases in the condenser. In the condenser, nano-refrigerants are not cool at the desired level, and the system was faulty. These drawbacks of the nano-particles mixed refrigerator have promoted the research and improving heat rejection rate in the condenser. In this article, vapour compression refrigeration system coupled with evaporative cooling pad, and nano-refrigerant, for improving the performance of the system in hot & dry weather is proposed and compared experimentally. Combined evaporative cooling system and ice plant test rig have been proposed for the appropriate heat rejection offered in the condenser due to a faulty system run at high pressure. The experimental investigations revealed that the performance characteristics of the evaporatively-cooled condenser are significantly enhanced. Maximum C.O.P. increases by about 51% in the hot and dry climate condition than the normal system.

Thermodynamic and economic studies of two new high efficient power-cooling cogeneration systems based on Kalina and absorption refrigeration cycles

International Nuclear Information System (INIS)

Rashidi, Jouan; Ifaei, Pouya; Esfahani, Iman Janghorban; Ataei, Abtin; Yoo, Chang Kyoo

2016-01-01

Highlights: • Proposing two new power and cooling cogeneration systems based on absorption chillers and Kalina cycles. • Model-based comparison through thermodynamic and economic standpoints. • Investigating sensitivity of system performance and costs to the key parameters. • Reducing total annual costs of the base system up to 8% by cogeneration. • Increasing thermal efficiency up to 4.9% despite of cooling generation. - Abstract: Two new power and cooling cogeneration systems based on Kalina cycle (KC) and absorption refrigeration cycle (AC) are proposed and studied from thermodynamic and economic viewpoints. The first proposed system, Kalina power-cooling cycle (KPCC), combines the refrigerant loop of the water-ammonia absorption chiller, consisting of an evaporator and two throttling valves with the KC. A portion of the KC mass flow enters the evaporator to generate cooling after being condensed in the KPCC system. KPCC is a flexible system adapting power and cooling cogeneration to the demand. The second proposed system, Kalina lithium bromide absorption chiller cycle (KLACC), consists of the KC and a single effect lithium bromide-water absorption chiller (AC_L_i_B_r_-_w_a_t_e_r). The KC subsystem discharges heat to the AC_L_i_B_r_-_w_a_t_e_r desorber before condensing in the condenser. The performance and economic aspects of both proposed systems are analyzed and compared with the stand alone KC. A parametric analysis is conducted to evaluate the sensitivity of efficiencies and the generated power and cooling quantities to the key operating variables. The results showed that, thermal efficiency and total annual costs decreased by 5.6% and 8% for KPCC system but increased 4.9% and 58% for KLACC system, respectively. Since the power-cooling efficiency of KLACC is 42% higher than KPCC it can be applied where the aim is cooling generation without considering economic aspects.

Thermoeconomic model of a commercial transcritical booster refrigeration system

DEFF Research Database (Denmark)

Ommen, Torben Schmidt; Elmegaard, Brian

2011-01-01

For cooling applications in supermarkets, booster refrigeration systems operating in both transcritical and subcritical conditions are increasingly used. A thermodynamic model of a transcritical booster refrigeration plant is tailored to match the new generation of commercial refrigeration plants...... of exergy for cooling. Second law analysis is needed to illustrate the characteristics of the plant at different load rates, according to the alternating load profile and corresponding to outdoor conditions. With the detailed model, different uses of the analysis are possible, including thermoeconomic...

Airborne exposure to trihalomethanes from tap water in homes with refrigeration-type and evaporative cooling systems.

Science.gov (United States)

Kerger, Brent D; Suder, David R; Schmidt, Chuck E; Paustenbach, Dennis J

2005-03-26

This study evaluates airborne concentrations of common trihalomethane compounds (THM) in selected living spaces of homes supplied with chlorinated tap water containing >85 ppb total THM. Three small homes in an arid urban area were selected, each having three bedrooms, a full bath, and approximately 1000 square feet; two homes had standard (refrigeration-type) central air conditioning and the third had a central evaporative cooling system ("swamp cooler"). A high-end water-use pattern was used at each home in this exposure simulation. THM were concurrently measured on 4 separate test days in tap water and air in the bathroom, living room, the bedroom closest to the bathroom, and outside using Summa canisters. Chloroform (trichloromethane, TCM), bromodichloromethane (BDCM), and dibromochloromethane (DBCM) concentrations were quantified using U.S. EPA Method TO-14. The apparent volatilization fraction consistently followed the order: TCM > BDCM > DBCM. Relatively low airborne THM concentrations (similar to outdoors) were found in the living room and bedroom samples for the home with evaporative cooling, while the refrigeration-cooled homes showed significantly higher THM levels (three- to fourfold). This differential remained after normalizing the air concentrations based on estimated THM throughput or water concentrations. These findings indicate that, despite higher throughput of THM-containing water in homes using evaporative coolers, the higher air exchange rates associated with these systems rapidly clears THM to levels similar to ambient outdoor concentrations.

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.

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.

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

Load management for refrigeration systems: Potentials and barriers

Energy Technology Data Exchange (ETDEWEB)

Grein, Arne, E-mail: a.grein@tu-berlin.de [University of Technology Berlin, Institute for Energy Technology, Department of Energy Systems, Einsteinufer 25 (TA8), 10587 Berlin (Germany); Pehnt, Martin [Institute for Energy and Environmental Research Heidelberg (ifeu), Wilckensstr. 3, 69120 Heidelberg (Germany)

2011-09-15

As a strategy to deal with the increasing intermittent input of renewable energy sources in Germany, the adaptation of power consumption is complementary to power-plant regulation, grid expansion and physical energy storage. One demand sector that promises strong returns for load management efforts is cooling and refrigeration. In these processes, thermal inertia provides a temporal buffer for shifting and adjusting the power consumption of cooling systems. We have conducted an empirical investigation to obtain a detailed and time-resolved bottom-up analysis of load management for refrigeration systems in the city of Mannheim, Germany. We have extrapolated our results to general conditions in Germany. Several barriers inhibit the rapid adoption of load management strategies for cooling systems, including informational barriers, strict compliance with legal cooling requirements, liability issues, lack of technical experience, an inadequate rate of return and organizational barriers. Small commercial applications of refrigeration in the food-retailing and cold storage in hotels and restaurants are particularly promising starting points for intelligent load management. When our results are applied to Germany, suitable sectors for load management have theoretical and achievable potential values of 4.2 and 2.8 GW, respectively, amounting to about 4-6% of the maximum power demand in Germany. - Highlights: > Potential and barriers for implementation of load shifting for refrigeration. > Empirical investigation for time-resolved bottom-up analysis in Mannheim, Germany. > Suitable sectors and further recommendations for introducing load management.> Extrapolation of results from local to national level.

Load management for refrigeration systems: Potentials and barriers

International Nuclear Information System (INIS)

Grein, Arne; Pehnt, Martin

2011-01-01

As a strategy to deal with the increasing intermittent input of renewable energy sources in Germany, the adaptation of power consumption is complementary to power-plant regulation, grid expansion and physical energy storage. One demand sector that promises strong returns for load management efforts is cooling and refrigeration. In these processes, thermal inertia provides a temporal buffer for shifting and adjusting the power consumption of cooling systems. We have conducted an empirical investigation to obtain a detailed and time-resolved bottom-up analysis of load management for refrigeration systems in the city of Mannheim, Germany. We have extrapolated our results to general conditions in Germany. Several barriers inhibit the rapid adoption of load management strategies for cooling systems, including informational barriers, strict compliance with legal cooling requirements, liability issues, lack of technical experience, an inadequate rate of return and organizational barriers. Small commercial applications of refrigeration in the food-retailing and cold storage in hotels and restaurants are particularly promising starting points for intelligent load management. When our results are applied to Germany, suitable sectors for load management have theoretical and achievable potential values of 4.2 and 2.8 GW, respectively, amounting to about 4-6% of the maximum power demand in Germany. - Highlights: → Potential and barriers for implementation of load shifting for refrigeration. → Empirical investigation for time-resolved bottom-up analysis in Mannheim, Germany. → Suitable sectors and further recommendations for introducing load management.→ Extrapolation of results from local to national level.

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...

Exergoeconomic Assessment of Solar Absorption and Absorption–Compression Hybrid Refrigeration in Building Cooling

Directory of Open Access Journals (Sweden)

Yue Jing

2018-02-01

Full Text Available The paper mainly deals with the match of solar refrigeration, i.e., solar/natural gas-driven absorption chiller (SNGDAC, solar vapor compression–absorption integrated refrigeration system with parallel configuration (SVCAIRSPC, and solar absorption-subcooled compression hybrid cooling system (SASCHCS, and building cooling based on the exergoeconomics. Three types of building cooling are considered: Type 1 is the single-story building, type 2 includes the two-story and three-story buildings, and type 3 is the multi-story buildings. Besides this, two Chinese cities, Guangzhou and Turpan, are taken into account as well. The product cost flow rate is employed as the primary decision variable. The result exhibits that SNGDAC is considered as a suitable solution for type 1 buildings in Turpan, owing to its negligible natural gas consumption and lowest product cost flow rate. SVCAIRSPC is more applicable for type 2 buildings in Turpan because of its higher actual cooling capacity of absorption subsystem and lower fuel and product cost flow rate. Additionally, SASCHCS shows the most extensive cost-effectiveness, namely, its exergy destruction and product cost flow rate are both the lowest when used in all types of buildings in Guangzhou or type 3 buildings in Turpan. This paper is helpful to promote the application of solar cooling.

Conduction cooling systems for linear accelerator cavities

Science.gov (United States)

Kephart, Robert

2017-05-02

A conduction cooling system for linear accelerator cavities. The system conducts heat from the cavities to a refrigeration unit using at least one cavity cooler interconnected with a cooling connector. The cavity cooler and cooling connector are both made from solid material having a very high thermal conductivity of approximately 1.times.10.sup.4 W m.sup.-1 K.sup.-1 at temperatures of approximately 4 degrees K. This allows for very simple and effective conduction of waste heat from the linear accelerator cavities to the cavity cooler, along the cooling connector, and thence to the refrigeration unit.

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.

POWER EFFICIENCY OPPORTUNITIES FOR INDUSTRIAL REFRIGERATION SYSTEM OF FOOD PROCESSING ENTERPRISE

Directory of Open Access Journals (Sweden)

O. Ostapenko

2016-12-01

Full Text Available Rising prices on power supply are forcing business owners to search the ways of operating costs reducing. Refrigeration system in the food industry is a major source of power consumption. The utilization of cold accumulation systems allows reducing of refrigeration unit power consumption. In this paper the refrigeration system with a system of cold accumulation and dry cooling tower is considered. The possibility of power consumption reducing due to the organization of the enterprise refrigeration system operation process in the night period according to electricity multiple tariffs has been analyzed.

Performance characteristics of low global warming potential R134a alternative refrigerants in ejector-expansion refrigeration system

Directory of Open Access Journals (Sweden)

Mishra Shubham

2016-12-01

Full Text Available Performance assessment of ejector-expansion vapor compression refrigeration system with eco-friendly R134a alternative refrigerants (R152a, R1234yf, R600a, R600, R290, R161, R32, and propylene is presented for air-conditioning application. Ejector has been modeled by considering experimental data based correlations of component efficiencies to take care of all irreversibilities. Ejector area ratio has been optimized based on maximum coefficient of performance (COP for typical air-conditioner operating temperatures. Selected refrigerants have been compared based on area ratio, pressure lift ratio, entrainment ratio, COP, COP improvement and volumetric cooling capacity. Effects of normal boiling point and critical point on the performances have been studied as well. Using ejector as an expansion device, maximum improvement in COP is noted in R1234yf (10.1%, which reduces the COP deviation with R134a (4.5% less in basic cycle and 2.5% less in ejector cycle. Hence, R1234yf seems to be best alternative for ejector expansion system due to its mild flammability and comparable volumetric capacity and cooling COP. refrigerant R161 is superior to R134a in terms of both COP and volumetric cooling capacity, although may be restricted for low capacity application due to its flammability.

Performance characteristics of low global warming potential R134a alternative refrigerants in ejector-expansion refrigeration system

Science.gov (United States)

Mishra, Shubham; Sarkar, Jahar

2016-12-01

Performance assessment of ejector-expansion vapor compression refrigeration system with eco-friendly R134a alternative refrigerants (R152a, R1234yf, R600a, R600, R290, R161, R32, and propylene) is presented for air-conditioning application. Ejector has been modeled by considering experimental data based correlations of component efficiencies to take care of all irreversibilities. Ejector area ratio has been optimized based on maximum coefficient of performance (COP) for typical air-conditioner operating temperatures. Selected refrigerants have been compared based on area ratio, pressure lift ratio, entrainment ratio, COP, COP improvement and volumetric cooling capacity. Effects of normal boiling point and critical point on the performances have been studied as well. Using ejector as an expansion device, maximum improvement in COP is noted in R1234yf (10.1%), which reduces the COP deviation with R134a (4.5% less in basic cycle and 2.5% less in ejector cycle). Hence, R1234yf seems to be best alternative for ejector expansion system due to its mild flammability and comparable volumetric capacity and cooling COP. refrigerant R161 is superior to R134a in terms of both COP and volumetric cooling capacity, although may be restricted for low capacity application due to its flammability.

Cogen-absorption plants for refrigeration purposes and turbine air inlet cooling

Energy Technology Data Exchange (ETDEWEB)

Langreck, Juergen [Colibri bv (Netherlands)

2000-04-01

Most cogeneration systems produce power and heat but with absorption refrigeration plants (ARP) the products are power and 'cold'. An ARP driven by heat from a turbine exhaust can provide the cooling for the inlet air with very low consumption of electricity, consequently there is a significant increase in power output from the cogeneration unit. Two different ARP systems are currently available but the author describes only the ammonia-water system, which can achieve temperatures down to -60 degrees C. The article discusses the principle behind ARP, the capital cost and returns on investment, how the cogeneration plant is linked to the ARP, ARP for turbine inlet air cooling, and the potential applications of cogeneration-ARP.

Solar-powered cooling system

Science.gov (United States)

Farmer, Joseph C.

2015-07-28

A solar-powered adsorption-desorption refrigeration and air conditioning system that uses nanostructural materials such as aerogels, zeolites, and sol gels as the adsorptive media. Refrigerant molecules are adsorbed on the high surface area of the nanostructural material while the material is at a relatively low temperature, perhaps at night. During daylight hours, when the nanostructural materials is heated by the sun, the refrigerant are thermally desorbed from the surface of the aerogel, thereby creating a pressurized gas phase in the vessel that contains the aerogel. This solar-driven pressurization forces the heated gaseous refrigerant through a condenser, followed by an expansion valve. In the condenser, heat is removed from the refrigerant, first by circulating air or water. Eventually, the cooled gaseous refrigerant expands isenthalpically through a throttle valve into an evaporator, in a fashion similar to that in more conventional vapor recompression systems.

Computer simulation with TRNSYS for a mobile refrigeration system incorporating a phase change thermal storage unit

International Nuclear Information System (INIS)

Liu, Ming; Saman, Wasim; Bruno, Frank

2014-01-01

Highlights: • A mobile refrigeration system incorporating phase change thermal storage was simulated using TRNSYS. • A TRNSYS component of a phase change thermal storage unit was created and linked to other components from TRNSYS library. • The temperature in the refrigerated space can be predicted using this TRNSYS model under various conditions. • A mobile refrigeration system incorporating PCM and an off-peak electric driven refrigeration unit is feasible. • The phase change material with the lowest melting temperature should be selected. - Abstract: This paper presents a new TRNSYS model of a refrigeration system incorporating phase change material (PCM) for mobile transport. The PCTSU is charged by an off-vehicle refrigeration unit and the PCM provides cooling when discharging and the cooling released is utilized to cool down the refrigerated space. The advantage of this refrigeration system compared to a conventional system is that it consumes less energy and produces significantly lower greenhouse gas emissions. A refrigeration system for a typical refrigerated van is modelled and simulations are performed with climatic data from four different locations. The main components of the TRNSYS model are Type 88 (cooling load estimation) and Type 300 (new PCTSU component), accompanied by other additional components. The results show that in order to maintain the temperature of the products at −18 °C for 10 h, a total of 250 kg and 390 kg of PCM are required for no door opening and 20 door openings during the transportation, respectively. In addition, a parametric study is carried out to evaluate the effects of location, size of the refrigerated space, number of door openings and melting temperature of the PCM on the thermal performance

46 CFR 151.40-11 - Refrigeration systems.

Science.gov (United States)

2010-10-01

... compressors shall be such that the required cooling capacity of the system is maintained with one compressor inoperative. Portions of the system other than the compressors need not have standby capacity. ... 46 Shipping 5 2010-10-01 2010-10-01 false Refrigeration systems. 151.40-11 Section 151.40-11...

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)

Comparative performance analysis of ice plant test rig with TiO2-R-134a nano refrigerant and evaporative cooled condenser

OpenAIRE

Amrat Kumar Dhamneya; S.P.S. Rajput; Alok Singh

2018-01-01

The nanoparticle is used in chillers for increasing system performance. The increasing concentration of nanoparticles (TiO2) in refrigerant increases the performances of the system due decreasing compressor work done and enhance heat transfer rate. For hot and dry climate condition, performances of air-cooled condenser minimize, and C. O. P. decreases extensively in chillers due to heat transfer rate decreases in the condenser. In the condenser, nano-refrigerants are not cool at the desired l...

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

Optimal Energy Consumption in Refrigeration Systems - Modelling and Non-Convex Optimisation

DEFF Research Database (Denmark)

Hovgaard, Tobias Gybel; Larsen, Lars F. S.; Skovrup, Morten J.

2012-01-01

Supermarket refrigeration consumes substantial amounts of energy. However, due to the thermal capacity of the refrigerated goods, parts of the cooling capacity delivered can be shifted in time without deteriorating the food quality. In this study, we develop a realistic model for the energy...... consumption in super market refrigeration systems. This model is used in a Nonlinear Model Predictive Controller (NMPC) to minimise the energy used by operation of a supermarket refrigeration system. The model is non-convex and we develop a computational efficient algorithm tailored to this problem...

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.

The control system of the ecological hybrid two stages refrigerating cycle

Directory of Open Access Journals (Sweden)

Cyklis Piotr

2016-01-01

Full Text Available The compression anticlockwise cycle is mostly used for refrigeration. However due to the environmental regulations, the use of classic refrigerants: F-gases is limited by international agreements. Therefore the combined compression-adsorption hybrid cycle with natural liquids: water/carbon dioxide working as the energy carriers is a promising solution. This allows to utilize the solar or waste energy for the refrigeration purpose. In this paper application of the solar collectors as the energy source for the adsorption cycle, coupled with the low temperature (LT refrigerating carbon dioxide compression cycle is shown. The control of the system is an essential issue to reduce the electric power consumption. The control of the solar heat supply and water sprayed cooling tower, for the adsorption cycle re-cooling, is presented in this paper. The designed control system and algorithm is related to the LT compression cycle, which operates according to the need of cold for the refrigeration chamber. The results of the laboratory investigations of the full system, showing the reduction of the energy consumption and maximum utilization of the solar heat for different control methods are presented.

Thermoeconomic Optimization of Cascade Refrigeration System Using Mixed Carbon Dioxide and Hydrocarbons at Low Temperature Circuit

Directory of Open Access Journals (Sweden)

Nasruddin Nasruddin

2016-12-01

Full Text Available Many applications and industrial processes require very low cooling temperature, such as cold storage in the biomedical field, requiring temperature below -80 °C. However,single-cycle refrigeration systems can only achieve the effective cooling temperature of -40 °C and, also, the performance of the cycle will decrease drastically for cooling temperatures lower than -35°C. Currently, most of cascade refrigeration systems use refrigerants that have ozone depletion potential (ODP and global warming potential (GWP, therefore, in this study, a cascade system is simulated using a mixture of environmentally friendly refrigerants, namely, carbon dioxide and a hydrocarbon (propane, ethane or ethylene as the refrigerant of the low temperature circuit. A thermodynamic analysis is performed to determine the optimal composition of the mixture of carbon dioxide and hydrocarbons in the scope of certain operating parameters. In addition, an economic analysis was also performed to determine the annual cost to be incurred from the cascade refrigeration system. The multi-objective/thermoeconomic optimization points out optimal operating parameter values of the system, to addressing both exergy efficiency and its relation to the costs to be incurred.

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

Detailed Design of Cooling Water System for Cold Neutron Source in HANARO

Energy Technology Data Exchange (ETDEWEB)

Kim, Bong Soo; Choi, Jung Woon; Kim, Y. K.; Wu, S. I.; Lee, Y. S

2007-04-15

To make cold neutron, a cryogenic refrigerator is necessary to transform moderator into cryogenic state so, thermal neutron is changed into cold neutron through heat transfer with moderator. A cryogenic refrigerator mainly consists of two apparatus, a helium compressor and a cold box which needs supply of cooling water. Therefore, cooling water system is essential to operate of cryogenic refrigerator normally. This report is mainly focused on the detailed design of the cooling water system for the HANARO cold neutron source, and describes design requirement, calculation, specification of equipment and water treatment method.

Detailed Design of Cooling Water System for Cold Neutron Source in HANARO

International Nuclear Information System (INIS)

Kim, Bong Soo; Choi, Jung Woon; Kim, Y. K.; Wu, S. I.; Lee, Y. S.

2007-04-01

To make cold neutron, a cryogenic refrigerator is necessary to transform moderator into cryogenic state so, thermal neutron is changed into cold neutron through heat transfer with moderator. A cryogenic refrigerator mainly consists of two apparatus, a helium compressor and a cold box which needs supply of cooling water. Therefore, cooling water system is essential to operate of cryogenic refrigerator normally. This report is mainly focused on the detailed design of the cooling water system for the HANARO cold neutron source, and describes design requirement, calculation, specification of equipment and water treatment method

Cryogenic cooling system for HTS cable

Energy Technology Data Exchange (ETDEWEB)

Yoshida, Shigeru [Taiyo Nippon Sanso, Tsukuba (Japan)

2017-06-15

Recently, Research and development activity of HTS (High Temperature Superconducting) power application is very progressive worldwide. Especially, HTS cable system and HTSFCL (HTS Fault current limiter) system are proceeding to practical stages. In such system and equipment, cryogenic cooling system, which makes HTS equipment cooled lower than critical temperature, is one of crucial components. In this article, cryogenic cooling system for HTS application, mainly cable, is reviewed. Cryogenic cooling system can be categorized into conduction cooling system and immersion cooling system. In practical HTS power application area, immersion cooling system with sub-cooled liquid nitrogen is preferred. The immersion cooling system is besides grouped into open cycle system and closed cycle system. Turbo-Brayton refrigerator is a key component for closed cycle system. Those two cooling systems are focused in this article. And, each design and component of the cooling system is explained.

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%

Solutions for Liquid Nitrogen Pre-Cooling in Helium Refrigeration Cycles

CERN Document Server

Wagner, U

2000-01-01

Pre-cooling of helium by means of liquid nitrogen is the oldest and one of the most common process features used in helium liquefiers and refrigerators. Its two principle tasks are to allow or increase the rate of pure liquefaction, and to permit the initial cool-down of large masses to about 80 K. Several arrangements for the pre-cooling process are possible depending on the desired application. Each arrangement has its proper advantages and drawbacks. The aim of this paper is to review the possible process solutions for liquid nitrogen pre-cooling and their particularities.

Gas hydrate cool storage system

Science.gov (United States)

Ternes, M.P.; Kedl, R.J.

1984-09-12

The invention presented relates to the development of a process utilizing a gas hydrate as a cool storage medium for alleviating electric load demands during peak usage periods. Several objectives of the invention are mentioned concerning the formation of the gas hydrate as storage material in a thermal energy storage system within a heat pump cycle system. The gas hydrate was formed using a refrigerant in water and an example with R-12 refrigerant is included. (BCS)

GreenChill Store Certification Protocol for Sub-Cooling Contained on Racks Separate from Refrigeration Equipment

Science.gov (United States)

Document describes the protocol used to determine the total load and refrigerant charge of stores that have placed all sub-cooling on a rack separate from all other commercial refrigeration equipment.

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.

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.

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

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)

Thermodynamic analysis of an absorption refrigeration system used to cool down the intake air in an Internal Combustion Engine

International Nuclear Information System (INIS)

Novella, R.; Dolz, V.; Martín, J.; Royo-Pascual, L.

2017-01-01

Highlights: • Enough power in the exhaust gases is available to operate the absorption cycle. • Three engine operating points are presented in the article. • Improvement potential up to 4% is possible in the engine indicated efficiency. • Engine indicated efficiency benefit was experimentally confirmed by direct testing. - Abstract: This paper deals with the thermodynamic analysis of an absorption refrigeration cycle used to cool down the temperature of the intake air in an Internal Combustion Engine using as a heat source the exhaust gas of the engine. The solution of ammonia-water has been selected due to the stability for a wide range of operating temperatures and pressures and the low freezing point. The effects of operating temperatures, pressures, concentrations of strong and weak solutions in the absorption refrigeration cycle were examined to achieve proper heat rejection to the ambient. Potential of increasing Internal Combustion Engine efficiency and reduce pollutant emissions was estimated by means of theoretical models and experimental tests. In order to provide boundary conditions for the absorption refrigeration cycle and to simulate its effect on engine performance, a 0D thermodynamic model was used to reproduce the engine performance when the intake air is cooled. Furthermore, a detailed experimental work was carried out to validate the results in real engine operation. Theoretical results show how the absorption refrigeration system decreases the intake air flow temperature down to a temperature around 5 °C and even lower by using the bottoming waste heat energy available in the exhaust gases in a wide range of engine operating conditions. In addition, the theoretical analysis estimates the potential of the strategy for increasing the engine indicated efficiency in levels up to 4% also at the operating conditions under evaluation. Finally, this predicted benefit in engine indicated efficiency has been experimentally confirmed by direct

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, ...

Optimization of a Two Stage Pulse Tube Refrigerator for the Integrated Current Lead System

Science.gov (United States)

Maekawa, R.; Matsubara, Y.; Okada, A.; Takami, S.; Konno, M.; Tomioka, A.; Imayoshi, T.; Hayashi, H.; Mito, T.

2008-03-01

Implementation of a conventional current lead with a pulse tube refrigerator has been validated to be working as an Integrated Current Lead (ICL) system for the Superconducting Magnetic Energy Storage (SMES). Realization of the system is primarily accounted for the flexibility of a pulse tube refrigerator, which does not posses any mechanical piston and/or displacer. As for an ultimate version of the ICL system, a High Temperature Superconducting (HTS) lead links a superconducting coil with a conventional copper lead. To ensure the minimization of heat loads to the superconducting coil, a pulse tube refrigerator has been upgraded to have a second cooling stage. This arrangement reduces not only the heat loads to the superconducting coil but also the operating cost for a SMES system. A prototype two-stage pulse tube refrigerator, series connected arrangement, was designed and fabricated to satisfy the requirements for the ICL system. Operation of the first stage refrigerator is a four-valve mode, while the second stage utilizes a double inlet configuration to ensure its confined geometry. The paper discusses the optimization of second stage cooling to validate the conceptual design

Performance evaluation of integrated trigeneration and CO2 refrigeration systems

International Nuclear Information System (INIS)

Suamir, IN.; Tassou, S.A.

2013-01-01

Food retailing is one of the most energy intensive sectors of the food cold chain. Its environmental impacts are significant not only because of the indirect effect from CO 2 emissions at the power stations but also due to the direct effect arising from refrigerant leakage to the atmosphere. The overall energy efficiency of supermarkets can be increased by integrating the operation of CO 2 refrigeration and trigeneration systems. This paper compares three alternative schemes in a medium size supermarket. Experimental results and simulation studies have shown that the best scheme for energy and GHG emissions savings is the one where the cooling produced by the trigeneration system is used to condense the CO 2 fluid in the refrigeration system to ensure subcritical operation throughout the year. It is shown that this system can produce 30% energy savings and over 40% greenhouse gas emissions savings over conventional refrigeration and indoor environment control systems in supermarkets.

The behaviour of a hybrid compressor and ejector refrigeration system with refrigerants 134a and 142b

Energy Technology Data Exchange (ETDEWEB)

Hernandez, J.I.; Best, R.; Estrada, C.A. [UNAM, Morelos (Mexico). Centro de Investigacion en Energia; Dorantes, R.J. [UAM Azcapotzalco, Reynosa Tamaulipas (Mexico). Dpto. de Energia

2004-09-01

A complete theoretical analysis on the thermodynamic behaviour of a HYbrid Compressor and Ejector Refrigeration System - HYCERS - is carried out. An ejector under optimum performance is employed. Two working fluids were selected: refrigerant 142b (HCFC 142b) which has shown very good characteristics in air conditioning applications of ejector systems and refrigerant 134a (HFC134a) which is widely used in refrigeration applications and readily available in most countries. The variation of the generator and condenser temperatures as well as the intercooler pressure were considered for an evaporator temperature of 10{sup o}C and a unitary cooling capacity of 1 kW. The ideal efficiency, the enthalpy-based coefficient of performance, the exergy efficiency and the supplied energy ratio are obtained. With this information, at a moderate condenser and generator temperature of 30 and 85{sup o}C, respectively, the HYCERS working with R134a had the best operation with a highest coefficient of performance of 0.48 and an exergy efficiency of 0.25. On the other hand, if a higher condenser temperature is imposed, the HYCERS with 142b had its best performance at a higher generator temperature. In selecting a working fluid the ejector subsystem behaviour is determinant in system performance. If a working fluid is badly selected, despite having high entrainment ratios, the system will not function properly. Therefore, the methodology here defined becomes an effective tool for selecting adequate working fluids and optimum system design conditions. Also, the employment of a unitary cooling load allows system scaling at any capacity as it increases linearly. (author)

Cooling systems for waste heat. Cooling systems, review and selection criteria. Kuehlsysteme fuer Abwaerme. Kuehlsysteme, Ueberblick und Auswahlkriterien

Energy Technology Data Exchange (ETDEWEB)

Mueller, W. (Jaeggi, Wallisellen (Switzerland))

1990-05-01

In many areas of ventilation, air-conditioning and refrigeration engineering, chemical and process engineering and energy production waste heat occurs. If a reduction in energy losses or heat recovery is not possible waste heat has to be drawn off through cooling systems. For this the following systems can be used: dry cooling systems, dry cooler with spray system, open-cycle wet cooler, hybrid dry cooler, and closed-cycle wet cooler. Particularly hybrid cooling systems can give acceptable solutions when the results with other systems are only unsatisfactory. (BWI).

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

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)

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.

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

SBIR Grant:No-Vibration Agile Cryogenic Optical Refrigerator

Energy Technology Data Exchange (ETDEWEB)

Epstein, Richard

2013-04-09

Optical refrigeration is currently the only all-solid-state cryocooling technology that has been demonstrated. Optical cryocoolers are devices that use laser light to cool small crystal or glass cooling elements. The cooling element absorbs the laser light and reradiates it at higher energy, an example of anti-Stokes fluorescence. The dif-ference between the energy of the outgoing and incoming light comes from the thermal energy of the cooling element, which in turn becomes colder. Entitled No-Vibration Agile Cryocoolers using Optical Refrigeration, this Phase I proposal directly addressed the continued development of the optical refrigerator components necessary to transition this scientific breakthrough into National Nu-clear Security Administration (NNSA) sensor applications in line with the objectives of topic 50b. ThermoDynamic Films LLC (TDF), in collaboration with the University of New Mexico (UNM), cooled an optical-refrigerator cooling element comprised of an ytterbium-doped yttrium lithium fluoride (Yb:YLF) crystal from room tempera-ture to 123 K with about 2% efficiency. This is the world record in optical refrigera-tion and an important step toward revolutionizing cryogenic systems for sensor ap-plications. During this period, they also designed and analyzed the crucial elements of a prototype optical refrigerator including the thermal link that connects the cool-ing element with the load.

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.

Optimization Strategies for a Portable Thermoelectric Vaccine Refrigeration System in Developing Communities

Science.gov (United States)

Ohara, B.; Sitar, R.; Soares, J.; Novisoff, P.; Nunez-Perez, A.; Lee, H.

2015-06-01

The traditional approach to determine an optimum current for thermoelectric cooling assumes that a refrigeration chamber is insulated and has no thermal resistance to a thermoelectric module. As a result, minimum temperature occurs when Peltier cooling matches with parasitic heat transfer and Joule heating. In practical application, minimum temperature happens when heat addition from the environment is matched with heat extracted by a thermoelectric module, and the optimum current differs from that anticipated by the traditional approach. Hence, consideration for insulation and thermal resistances via thermoelectric module should be made to achieve desirable cooling performance/refrigeration temperature. This paper presents a modeling approach to determine the optimum current as well as the optimum geometry to power a small thermoelectric vaccine delivery system for developing communities under the World Health Organization requirements. The model is derived from three energy conservation equations for temperatures at both ends of the thermoelectric materials within a module, as well as the refrigeration chamber temperature. A prototype was built and demonstrated a minimum temperature of 3.4°C. With optimized module geometry, the system is estimated to reduce power consumption by over 50% while achieving twice the temperature difference.

Analysis on energy saving potential of integrated supermarket HVAC and refrigeration systems using multiple subcoolers

Energy Technology Data Exchange (ETDEWEB)

Yang, Liang [Institute of Refrigeration and Cryogenics, Shanghai Jiaotong University, Shanghai 200240 (China); China R and D Center, Carrier Corporation, No. 3239 Shen Jiang Road, Shanghai 201206 (China); Zhang, Chun-Lu [China R and D Center, Carrier Corporation, No. 3239 Shen Jiang Road, Shanghai 201206 (China)

2010-02-15

The paper presents a model-based analysis on the energy saving potential of supermarket HVAC (heating, ventilating, and air-conditioning) and refrigeration systems using multiple subcoolers among the high-temperature HVAC system, the medium-temperature refrigeration system, and the low-temperature refrigeration system. The principle of energy reduction is to have the higher COP (coefficient of performance) system generate more cooling capacity to increase the cooling capacity or reduce the power consumption of the lower COP system. The subcooler could be placed between the medium-temperature and low-temperature systems, between the high-temperature and medium-temperature systems, and between the high-temperature and low-temperature systems. All integration scenarios of adding one, two and three subcoolers have been investigated. The energy saving potential varies with the load ratio between high-, medium- and low-temperature systems, COP of three systems, and the ''on-off'' duty time of HVAC system. The optimal sequence of adding subcoolers is also proposed. (author)

Smart Cooling Controlled System Exploiting Photovoltaic Renewable Energy Systems

Directory of Open Access Journals (Sweden)

Ahmad Atieh

2018-03-01

Full Text Available A smart cooling system to control the ambient temperature of a premise in Amman, Jordan, is investigated and implemented. The premise holds 650 people and has 14 air conditioners with the cooling capacity ranging from 3 to 5 ton refrigerant (TR each. The control of the cooling system includes implementing different electronics circuits that are used to sense the ambient temperature and humidity, count the number of people in the premise and then turn ON/OFF certain air conditioner(s. The data collected by different electronic circuits are fed wirelessly to a microcontroller, which decides which air conditioner will be turned ON/OFF, its location and its desired set cooling temperature. The cooling system is integrated with an on-grid solar photovoltaic energy system to minimize the operational cost of the overall cooling system.

Water cooling system for sintering furnaces of nuclear fuel pellets

International Nuclear Information System (INIS)

1996-01-01

This work has as a main objective to develop a continuous cooling water system, which is necessary for the cooling of the sintering furnaces. This system is used to protect them as well as for reducing the water consumption, ejecting the heat generated into this furnaces and scattering it into the atmosphere in a fast and continuous way. The problem was defined and the reference parameters established, making the adequate research. The materials were selected as well as the length of the pipeline which will carry the secondary refrigerant fluid (water). Three possible solutions were tried,and evaluated, and from these, the thermal and economically most efficient option was selected. The layout of the solution was established and the theoretical construction of a cooling system for liquids using dichlorofluoromethane (R-22), as a refrigerant and a air cooled condenser, was accomplished. (Author)

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

Comparative analysis of thermally activated, environmentally friendly cooling systems

International Nuclear Information System (INIS)

Gupta, Y.; Metchop, L.; Frantzis, A.; Phelan, P.E.

2008-01-01

This paper compares the relative performances of three different thermally activated, environmentally friendly cooling systems, e.g. a silica-gel-water adsorption system, a LiBr-H 2 O absorption system and a desiccant air system. The adsorption and absorption systems in the current study employ water as the refrigerant, while the desiccant system cools atmospheric air directly. Each of these systems can be utilized at relatively low heat source temperatures such as achieved by flat plate solar collectors, but it is unclear which of these systems is best suited to what range of heat source temperature. Our study explores answers to this question by generating quantitative results comparing their relative thermal performance, i.e. COP and refrigeration capacity, and a qualitative comparison based on the size, maturity of technology, safe operation etc. In order to provide a fair comparison between the fundamentally different systems, a UA (overall heat transfer coefficient multiplied by the heat transfer area) value of 1.0 kW deg. C -1 is considered for the heat exchanger that transfers heat from the supplied hot water. Furthermore, to compare systems of similar size, the mass of silica-gel in the adsorption and desiccant systems and the mass of LiBr-H 2 O solution in the absorption system were specified such that each system provides the same amount of refrigeration (8.0 kW) at a source temperature of 90 deg. C. It is found that the absorption and adsorption cooling systems have a higher refrigeration capacity at heat source temperatures below 90 deg. C, while the desiccant air system outperforms the others at temperatures above 90 deg. C

Dynamic simulation of variable capacity refrigeration systems under abnormal conditions

International Nuclear Information System (INIS)

Liang Nan; Shao Shuangquan; Tian Changqing; Yan Yuying

2010-01-01

There are often abnormal working conditions at evaporator outlet of a refrigeration system, such as two-phase state in transient process, and it is essential to investigate such transient behaviours for system design and control strategy. In this paper, a dynamic lumped parameter model is developed to simulate the transient behaviours of refrigeration system with variable capacity in both normal and abnormal working conditions. The appropriate discriminant method is adopted to switch the normal and abnormal conditions smoothly and to eliminate the simulated data oscillation. In order to verify the dynamic model, we built a test system with variable frequency compressor, water-cooling condenser, evaporator and electronic expansion valve. Calculated values from the mathematical model show reasonable agreement with the experimental data. The simulation results show that the transient behaviours of the variable capacity refrigeration system in the abnormal working conditions can be calculated reliably with the dynamic model when the compressor rotary speed or the opening of electronic expansion valve changes abruptly.

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]....

Helium refrigerator-liquefier system for MHD generator

International Nuclear Information System (INIS)

Akiyama, Y.; Ishii, H.; Mori, Y.; Yamamoto, M.; Wada, R.; Ando, M.

1974-01-01

MHD power generators have been investigated in the Electro-Technical Laboratory as one of the National Research and Development Programmes. A helium refrigerator-liquefier system has been developed to cool the superconducting magnet for a 1000 kW class MHD power generator. The turboexpander with low temperature gas bearings and an alternator had been developed for the MHD project at the Electro-Technical Laboratory previously. The liquefaction capacity is 250 iota/h and the refrigeration power is 2.9 kW at 20 K. The superconducting magnet is 50 tons and the cryostat has a liquid helium volume of 2700 iota. The evaporation rate is 60 to 80 iota/h. It takes, in all 2 to 3 weeks to fill the cryostat with liquid helium. (author)

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.

Heat pump system with selective space cooling

Science.gov (United States)

Pendergrass, J.C.

1997-05-13

A reversible heat pump provides multiple heating and cooling modes and includes a compressor, an evaporator and heat exchanger all interconnected and charged with refrigerant fluid. The heat exchanger includes tanks connected in series to the water supply and a condenser feed line with heat transfer sections connected in counterflow relationship. The heat pump has an accumulator and suction line for the refrigerant fluid upstream of the compressor. Sub-cool transfer tubes associated with the accumulator/suction line reclaim a portion of the heat from the heat exchanger. A reversing valve switches between heating/cooling modes. A first bypass is operative to direct the refrigerant fluid around the sub-cool transfer tubes in the space cooling only mode and during which an expansion valve is utilized upstream of the evaporator/indoor coil. A second bypass is provided around the expansion valve. A programmable microprocessor activates the first bypass in the cooling only mode and deactivates the second bypass, and vice-versa in the multiple heating modes for said heat exchanger. In the heating modes, the evaporator may include an auxiliary outdoor coil for direct supplemental heat dissipation into ambient air. In the multiple heating modes, the condensed refrigerant fluid is regulated by a flow control valve. 4 figs.

The effect of cool water pack preparation on vaccine vial temperatures in refrigerators.

Science.gov (United States)

Goldwood, Geneva; Diesburg, Steven

2018-01-02

Cool water packs are a useful alternative to ice packs for preventing unintentional freezing of vaccines during outreach in some situations. Current guidelines recommend the use of a separate refrigerator for cooling water packs from ambient temperatures to prevent possible heat degradation of adjacent vaccine vials. To investigate whether this additional equipment is necessary, we measured the temperatures that vaccine vials were exposed to when warm water packs were placed next to vials in a refrigerator. We then calculated the effect of repeated vial exposure to those temperatures on vaccine vial monitor status to estimate the impact to the vaccine. Vials were tested in a variety of configurations, varying the number and locations of vials and water packs in the refrigerator. The calculated average percentage life lost during a month of repeated warming ranged from 20.0% to 30.3% for a category 2 (least stable) vaccine vial monitor and from 3.8% to 6.0% for a category 7 (moderate stability) vaccine vial monitor, compared to 17.0% for category 2 vaccine vial monitors and 3.1% for category 7 vaccine vial monitors at a constant 5 °C. The number of vials, number of water packs, and locations of each impacted vial warming and therefore percentage life lost, but the vaccine vial monitor category had a higher impact on the average percentage life lost than any of the other parameters. The results suggest that damage to vaccines from repeated warming over the course of a month is not certain and that cooling water packs in a refrigerator where vaccines are being stored may be a useful practice if safe procedures are established. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Thermodynamic design of hydrogen liquefaction systems with helium or neon Brayton refrigerator

Science.gov (United States)

Chang, Ho-Myung; Ryu, Ki Nam; Baik, Jong Hoon

2018-04-01

A thermodynamic study is carried out for the design of hydrogen liquefaction systems with helium (He) or neon (Ne) Brayton refrigerator. This effort is motivated by our immediate goal to develop a small-capacity (100 L/h) liquefier for domestic use in Korea. Eight different cycles are proposed and their thermodynamic performance is investigated in comparison with the existing liquefaction systems. The proposed cycles include the standard and modified versions of He Brayton refrigerators whose lowest temperature is below 20 K. The Brayton refrigerator is in direct thermal contact with the hydrogen flow at atmospheric pressure from ambient-temperature gas to cryogenic liquid. The Linde-Hampson system pre-cooled by a Ne Brayton refrigerator is also considered. Full cycle analysis is performed with the real properties of fluids to estimate the figure of merit (FOM) under an optimized operation condition. It is concluded that He Brayton refrigerators are feasible for this small-scale liquefaction, because a reasonably high efficiency can be achieved with simple and safe (low-pressure) operation. The complete cycles with He Brayton refrigerator are presented for the development of a prototype, including the ortho-to-para conversion.

Prediction and analysis of the seasonal performance of tri-generation and CO2 refrigeration systems in supermarkets

International Nuclear Information System (INIS)

Ge, Y.T.; Tassou, S.A.; Suamir, I.N.

2013-01-01

Highlights: ► Integration model of a trigeneration with CO 2 refrigeration systems in supermarket. ► Validation of the developed integration model with site and laboratory measurement. ► Application of the trigeneration system in power generation and space conditioning. ► Performance analysis and comparison of the integrated system in supermarket. - Abstract: A modern supermarket energy control system has a concurrent need for electricity, space heating or cooling, and food refrigeration. The power supply to the supermarket is primarily from the national grid, where losses in efficiency are due to the processes of energy conversion and transmission. Combined heat and power (CHP) offers the potential to locally produce electrical power and heating which could save energy and reduce CO 2 emissions in the long run. During the summer months, as the space heating requirement in a supermarket is relatively small, the energy efficiency of a CHP installation can be improved by using excess thermal energy to drive a sorption refrigeration system to provide space cooling or refrigeration. This process is also known as tri-generation. In recent years, the use of CO 2 as a refrigerant in supermarkets has received considerable attention due to its negligible contribution to direct greenhouse gas emissions and excellent thermophysical and heat transfer properties. Consequently, the application of a tri-generation system in a supermarket with CO 2 refrigeration merits further investigation. In this paper, to evaluate the performance of a tri-generation system in the supermarket, a previously tested 80 kWe microturbine device was applied into an operational supermarket to generate power and provide space heating and cooling through exhaust heat. The performance evaluation and comparison for this tri-generation application is based on the prediction from an integrated model of supermarket energy control, cascade CO 2 refrigeration and tri-generation systems. The results

4 K to 20 K rotational-cooling magnetic refrigerator capable of 1-mW to >1-W operation

International Nuclear Information System (INIS)

Barclay, J.A.

1980-02-01

The low-temperature, magnetic entropy of certain single-crystal paramagnetic materials, such as DyPO 4 , changes dramatically as the crystal rotates in a magnetic field. A new magnetic refrigerator design based on the anisotropic nature of such materials is presented. The key advantages of the rotational-cooling concept are (1) a single, rotary motion is required, (2) magnetic field shaping is not a problem because the entire working material is in a constant field, and (3) the refrigerator can be smaller than comparable magnetic refrigerators because the working material is entirely inside the magnet at all times. The main disadvantage of the rotational-cooling concept is that small-dimension single crystals are required

A Case Study of a Low Powervapour Compression Refrigeration System

Science.gov (United States)

Abinav, R.; Nambiar, G. K.; Sahu, Debjyoti

2016-09-01

Reported in this paper is a case study on a normal vapor compression refrigeration system which is expected to be run by photovoltaic panels to utilize minimum grid power. A small 120 W refrigerator is fabricated out of commercially available components and run by an inverter and battery connected to solar photovoltaic panel as well as grid. Temperature at several points was measured and the performance was evaluated. The Coefficient of performance (COP) to run such refrigerator is estimated after numerical simulation of major components namely, evaporator, condenser and a capillary tube. The simulation was done to obtain an effective cooling temperature and the results were compared with measured temperatures. Calculation proves to be in conformity with the actual model.

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.

46 CFR 154.1720 - Indirect refrigeration.

Science.gov (United States)

2010-10-01

... Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Special Design and Operating Requirements § 154.1720 Indirect refrigeration. A refrigeration system that is used to cool acetaldehyde, ethylene...

Evaluation of Variable Refrigerant Flow Systems Performance on Oak Ridge National Laboratory s Flexible Research Platform: Part 1 Cooling Season Analysis

Energy Technology Data Exchange (ETDEWEB)

Im, Piljae [ORNL; Malhotra, Mini [ORNL; Munk, Jeffrey D [ORNL

2016-08-01

This report provides second-year cooling season test results for the multi-year project titled “Evaluation of Variable Refrigeration Flow (VRF) System on Oak Ridge National Laboratory (ORNL)’s Flexible Research Platform (FRP).” The purpose of the second-year project was to (1) evaluate the full- and partload performance of VRF systems compared with an existing baseline heating, ventilation, and airconditioning (HVAC) system, which is a conventional rooftop unit (RTU) variable-air-volume (VAV) system with electric resistance heating and (2) use hourly building energy simulation to evaluate the energy savings potential of using VRF systems in major US cities. The second-year project performance period was from July 2015 through June 2016.

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.

Accelerator-based cold neutron sources and their cooling system

International Nuclear Information System (INIS)

Inoue, Kazuhiko; Yanai, Masayoshi; Ishikawa, Yoshikazu.

1985-01-01

We have developed and installed two accelerator-based cold neutron sources within a electron linac at Hokkaido University and a proton synchrotoron at National Laboratory for High Energy Physics. Solid methane at 20K was adopted as the cold moderator. The methane condensing heat exchangers attached directly to the moderator chambers were cooled by helium gas, which was kept cooled in refrigerators and circulated by ventilation fans. Two cold neutron sources have operated smoothly and safely for the past several years. In this paper we describe some of the results obtained in the preliminary experiments by using a modest capacity refrigerator, the design philosophy of the cooling system for the pulsed cold neutron sources, and outline of two facilities. (author)

Experimental Investigation of Air Conditioner using the Desiccant Cooling System in Equatorial Climates

Directory of Open Access Journals (Sweden)

Abdullah Kamaruddin

2018-01-01

Full Text Available Indonesia lies in the tropical climate which requires air conditioning to increase working productivity of the people. Up to now people are still using the compressive cooling system which uses Freon as the refrigerant, which have been known to have a negative environmental impact. Therefore, new cooling system which is environmentally friendly is now needed. Desiccant cooling system manipulates the humidity condition of outside air in such a way so that the final temperature should become at 25 °C and RH of 65 %. Since it does not require refrigerant, a desiccant cooling has the potential to be developed in a tropical country like Indonesia. In this study an experimental desiccant cooling system has been designed and constructed and tested under laboratory condition. Experimental results have shown that the resulting air temperature was 26.1 °C with RH of 55.6 %, and average cooling capacity was 0.425 kW. The COP was found to be 0.44.

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.

Cooling system for auxiliary systems of a nuclear power plant

International Nuclear Information System (INIS)

Maerker, W.; Mueller, K.; Roller, W.

1981-01-01

From the reactor auxiliary and ancillary systems of a nuclear facility heat has to be removed without the hazard arising that radioactive liquids or gases may escape from the safe area of the nuclear facility. A cooling system is described allowing at every moment to make available cooling fluid at a temperature sufficiently low for heat exchangers to be able to remove the heat from such auxiliary systems without needing fresh water supply or water reservoirs. For this purpose a dry cooling tower is connected in series with a heat exchanger that is cooled on the secondary side by means of a refrigerating machine. The cooling pipes are filled with a nonfreezable fluid. By means of a bypass a minimum temperature is guaranteed at cold weather. (orig.) [de

Experimental analysis of a diffusion absorption refrigeration system used alternative energy sources

International Nuclear Information System (INIS)

Soezen, A.; Oezbas, E.

2009-01-01

The continuous-cycle absorption refrigeration device is widely used in domestic refrigerators, and recreational vehicles. It is also used in year-around air conditioning of both homes and larger buildings. The unit consists of four main parts the boiler, condenser, evaporator and the absorber. When the unit operates on kerosene or gas, the heat is supplied by a burner. This element is fitted underneath the central tube. When operating on electricity, the heat is supplied by an element inserted in the pocket. No moving parts are employed. The operation of the refrigerating mechanism is based on Dalton's law. In this study, experimental analysis was performed of a diffusion absorption refrigeration system (DARS) used alternative energy sources such as solar, liquid petroleum gas (LPG) sources. Two basic DAR cycles were set up and investigated: i) In the first cycle (DARS-1), the condensate is sub-cooled prior to the evaporator entrance by the coupled evaporator/gas heat exchanger similar with manufactured by Electrolux Sweden. ii) In the second cycle (DARS-2), the condensate is not sub-cooled prior to the evaporator entrance and gas heat exchanger is separated from the evaporator. (author)

Cooling performance and energy saving of a compression-absorption refrigeration system assisted by geothermal energy

International Nuclear Information System (INIS)

Kairouani, L.; Nehdi, E.

2006-01-01

The objectives of this paper are to develop a novel combined refrigeration system, and to discuss the thermodynamic analysis of the cycle and the feasibility of its practical development. The aim of this work was to study the possibility of using geothermal energy to supply vapour absorption system cascaded with conventional compression system. Three working fluids (R717, R22, and R134a) are selected for the conventional compression system and the ammonia-water pair for the absorption system. The geothermal temperature source in the range 343-349 K supplies a generator operating at 335 K. Results show that the COP of a combined system is significantly higher than that of a single stage refrigeration system. It is found that the COP can be improved by 37-54%, compared with the conventional cycle, under the same operating conditions, that is an evaporation temperature at 263 K and a condensation temperature of 308 K. For industrial refrigeration, the proposed system constitutes an alternative solution for reducing energy consumption and greenhouse gas emissions

Synchronous temperature rate control for refrigeration with reduced energy consumption

Science.gov (United States)

Gomes, Alberto Regio; Keres, Stephen L.; Kuehl, Steven J.; Litch, Andrew D.; Richmond, Peter J.; Wu, Guolian

2015-09-22

Methods of operation for refrigerator appliance configurations with a controller, a condenser, at least one evaporator, a compressor, and two refrigeration compartments. The configuration may be equipped with a variable-speed or variable-capacity compressor, variable speed evaporator or compartment fans, a damper, and/or a dual-temperature evaporator with a valve system to control flow of refrigerant through one or more pressure reduction devices. The methods may include synchronizing alternating cycles of cooling each compartment to a temperature approximately equal to the compartment set point temperature by operation of the compressor, fans, damper and/or valve system. The methods may also include controlling the cooling rate in one or both compartments. Refrigeration compartment cooling may begin at an interval before or after when the freezer compartment reaches its lower threshold temperature. Freezer compartment cooling may begin at an interval before or after when the freezer compartment reaches its upper threshold temperature.

Synchronous temperature rate control for refrigeration with reduced energy consumption

Energy Technology Data Exchange (ETDEWEB)

Gomes, Alberto Regio; Keres, Stephen L.; Kuehl, Steven J.; Litch, Andrew D.; Richmond, Peter J.; Wu, Guolian

2017-11-07

Methods of operation for refrigerator appliance configurations with a controller, a condenser, at least one evaporator, a compressor, and two refrigeration compartments. The configuration may be equipped with a variable-speed or variable-capacity compressor, variable speed evaporator or compartment fans, a damper, and/or a dual-temperature evaporator with a valve system to control flow of refrigerant through one or more pressure reduction devices. The methods may include synchronizing alternating cycles of cooling each compartment to a temperature approximately equal to the compartment set point temperature by operation of the compressor, fans, damper and/or valve system. The methods may also include controlling the cooling rate in one or both compartments. Refrigeration compartment cooling may begin at an interval before or after when the freezer compartment reaches its lower threshold temperature. Freezer compartment cooling may begin at an interval before or after when the freezer compartment reaches its upper threshold temperature.

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.

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.

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

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.

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.

Numerical model for thermoeconomic diagnosis in commercial transcritical/subcritical booster refrigeration systems

International Nuclear Information System (INIS)

Ommen, Torben; Elmegaard, Brian

2012-01-01

Highlights: ► A transcritical booster refrigeration plant is modelled. ► We examine changes in cost flow at different operation parameters. ► The use of characteristic curves for diagnosis is studied. - Abstract: Transcritical/subcritical booster refrigeration systems are increasingly installed and used in Danish supermarkets. The systems operate in both transcritical and subcritical conditions dependent on the heat rejection performance and the ambient conditions. The plant consists of one refrigerant cycle supplying refrigerant for evaporators in both chilled and frozen display cases. In the paper, thermoeconomic theory is used to establish the cost of cooling at each individual temperature level based on operating costs. With a high amount of operating systems, faulty operation becomes an economic, and environmental, interest. A general solution for evaluation of these systems is considered, with the objective to reduce cost and power consumption of malfunctioning equipment in operation. An analysis of the use of thermoeconomic diagnosis methods is required, as these methods may prove applicable. To accommodate the analysis, a numerical model of a transcritical booster refrigeration plant is considered in this paper. Additionally the characteristic curves method is applied to the high pressure compressor unit of the refrigeration plant. The approach successfully determine whether an anomaly is intrinsic or induced in the component when no uncertainties are introduced in the steady state model.

PARAMETRIC STUDY OF ENERGY, EXERGY AND THERMOECONOMIC ANALYSES ON VAPOR-COMPRESSION SYSTEM CASCADED WITH LIBR/WATER AND NH3/WATER ABSORBTION CASCADE REFRIGERATION CYCLE

Directory of Open Access Journals (Sweden)

ahmet selim dalkilic

2017-03-01

Full Text Available Energy savings on cooling systems can be performed by using novel refrigeration cycles. For this aim, vapour compression-vapour absorption cascade refrigeration systems can be considered as substitute to single-stage vapour compression refrigeration systems. Renewable energy sources of geothermal and solar heat, waste heat of processes have been used by these cycles to provide cooling and they also require less electrical energy than vapour compression cycles having alternative refrigerants. In this study, a vapour compression (VC and vapour absorption (VA cascade systems are analysed with the second law analysis for varied cooling capacities. While lithium bromide-water and NH3/H2O are the working fluids in VA part, various refrigerants are used in VC section. The refrigerants of R134a and R600a, R410A and R407C are tested as drop in alternatives for R12 and R22, respectively. The effects of alteration in cooling capacity, superheating and sub cooling in VC part, temperature in the generator and absorber, and degree of overlap in cascade condenser in VA part on the coefficient of system performance are studied. Validation of the results have been performed by the values given in the literature. Improvement in COP of VC, VA and cascade system are obtained separately. According to the analyses, cascade systems’ COP values increase with increasing the temperatures of generator and evaporator and they also increase with decreasing the condenser and absorber temperatures. Moreover, the generator has the highest exergy destruction rates, second and third one were the condenser and absorber, respectively. Electricity consumption and payback period are also determined considering the various parameters of the study.

Development and Analysis of Hybrid Thermoelectric Refrigerator Systems

Science.gov (United States)

Saifizi, M.; Zakaria, M. S.; Yaacob, Sazali; Wan, Khairunizam

2018-03-01

Thermoelectric module (TEM) is a type of solid-state devices which has the capability to maintain the accuracy of small temperature variation application. In this study, a hybrid thermoelectric refrigerator system is introduced by utilizing TEMs; direct and air to air thermoelectric heat pump to cool down and maintain low temperature for vaccines storage. Two different materials which are aluminum and stainless steel are used as container in hybrid thermoelectric refrigerator (HTER) configuration to investigate the response of every system in transient and steady state mode. A proper temperature sensor calibration technique is implemented to make certain real time data acquisition of the systems are not affected very much from the noise generated. From step response analysis, it is indicated that HTER I (aluminum) has rapid settling time from transient to steady state than HTER II (stainless steel) since aluminum has better thermal conductivity as compared to stainless steel. It is found that HTER I is better in cooling capability with the same input current instead of HTER II which required a longer time to achieve steady state mode. Besides, in Pseudo Random Binary Sequence (PRBS) response analysis injected to both systems shows HTER I is very sensitive to current input as the sequence length of HTER I is shorter than HTER II. However both systems depict the varying temperature in the range of 4 oC due to differences in thermal conductivity of container.

Refrigeration system with a compressor-pump unit and a liquid-injection desuperheating line

Science.gov (United States)

Gaul, Christopher J.

2001-01-01

The refrigeration system includes a compressor-pump unit and/or a liquid-injection assembly. The refrigeration system is a vapor-compression refrigeration system that includes an expansion device, an evaporator, a compressor, a condenser, and a liquid pump between the condenser and the expansion device. The liquid pump improves efficiency of the refrigeration system by increasing the pressure of, thus subcooling, the liquid refrigerant delivered from the condenser to the expansion device. The liquid pump and the compressor are driven by a single driving device and, in this regard, are coupled to a single shaft of a driving device, such as a belt-drive, an engine, or an electric motor. While the driving device may be separately contained, in a preferred embodiment, the liquid pump, the compressor, and the driving device (i.e., an electric motor) are contained within a single sealable housing having pump and driving device cooling paths to subcool liquid refrigerant discharged from the liquid pump and to control the operating temperature of the driving device. In another aspect of the present invention, a liquid injection assembly is included in a refrigeration system to divert liquid refrigerant from the discharge of a liquid pressure amplification pump to a compressor discharge pathway within a compressor housing to desuperheat refrigerant vapor to the saturation point within the compressor housing. The liquid injection assembly includes a liquid injection pipe with a control valve to meter the volume of diverted liquid refrigerant. The liquid injection assembly may also include a feedback controller with a microprocessor responsive to a pressure sensor and a temperature sensor both positioned between the compressor to operate the control valve to maintain the refrigerant at or near saturation.

Design and performance prediction of solar adsorption cooling for mobile vaccine refrigerator

Science.gov (United States)

Djubaedah, Euis; Taufan, Andi; Ratnasari, Nadhira; Fahrizal, Adjie; Hamidi, Qayyum; Nasruddin

2017-03-01

Adsorption cooling is a process that uses a drop-in pressure caused by the adsorption of adsorbate by adsorbent. Adsorption process creates a pressure drop which can bring down the temperature to the intended condition. This approach can be used in vaccine transportation as the vaccines need to be stored at low temperatures (2°C to 8°C for preserving vaccines). The pressure decrease can be obtained by adsorption water in zeolites and can also produce the temperature drop in the main chamber. The adsorption process of water will decrease until reaching saturation condition. Heat is needed to keep the system continuous as it starts a desorption process. From the simulation using MATLAB, it is found that the mobile vaccine refrigerator can reach the temperature of 2°C in 180 seconds with the amount of cooling power generated is up to 1530 W. The insulation can hold the allowable temperature range inside the vaccine cabin for 15.6795 hours.

Experimental System of Solar Adsorption Refrigeration with Concentrated Collector.

Science.gov (United States)

Yuan, Z X; Li, Y X; Du, C X

2017-10-18

To improve the performance of solar adsorption refrigeration, an experimental system with a solar concentration collector was set up and investigated. The main components of the system were the adsorbent bed, the condenser, the evaporator, the cooling sub-system, and the solar collector. In the first step of the experiment, the vapor-saturated bed was heated by the solar radiation under closed conditions, which caused the bed temperature and pressure to increase. When the bed pressure became high enough, the bed was switched to connect to the condenser, thus water vapor flowed continually from the bed to the condenser to be liquefied. Next, the bed needed to cool down after the desorption. In the solar-shielded condition, achieved by aluminum foil, the circulating water loop was opened to the bed. With the water continually circulating in the bed, the stored heat in the bed was took out and the bed pressure decreased accordingly. When the bed pressure dropped below the saturation pressure at the evaporation temperature, the valve to the evaporator was opened. A mass of water vapor rushed into the bed and was adsorbed by the zeolite material. With the massive vaporization of the water in the evaporator, the refrigeration effect was generated finally. The experimental result has revealed that both the COP (coefficient of the performance of the system) and the SCP (specific cooling power of the system) of the SAPO-34 zeolite was greater than that of the ZSM-5 zeolite, no matter whether the adsorption time was longer or shorter. The system of the SAPO-34 zeolite generated a maximum COP of 0.169.

Computational Fluid Dynamics Analysis of an Evaporative Cooling System

Directory of Open Access Journals (Sweden)

Kapilan N.

2016-11-01

Full Text Available The use of chlorofluorocarbon based refrigerants in the air-conditioning system increases the global warming and causes the climate change. The climate change is expected to present a number of challenges for the built environment and an evaporative cooling system is one of the simplest and environmentally friendly cooling system. The evaporative cooling system is most widely used in summer and in rural and urban areas of India for human comfort. In evaporative cooling system, the addition of water into air reduces the temperature of the air as the energy needed to evaporate the water is taken from the air. Computational fluid dynamics is a numerical analysis and was used to analyse the evaporative cooling system. The CFD results are matches with the experimental results.

Field measurements of supermarket refrigeration systems. Part I: Analysis of CO2 trans-critical refrigeration systems

International Nuclear Information System (INIS)

Sawalha, Samer; Karampour, Mazyar; Rogstam, Jörgen

2015-01-01

This study investigates the refrigeration performance of three CO 2 trans-critical solutions based on field measurements. The measurements are carried out in five supermarkets in Sweden. Using the field measurements, low and medium temperature level cooling capacities and COP's are calculated for ten-minute intervals, filtered and averaged to monthly values. The results indicate that the systems using trans-critical booster system with gas removal from the intermediate vessel have relatively the highest total COP. The reasons are higher evaporation temperatures, lower internal and external superheat and higher total efficiency of booster compressors. Another important factor is gas removal from the intermediate vessel which leads to higher COP of low temperature level. Comparing the older and newer installed systems, a trend in energy efficiency improvement has been seen. The study shows this improvement originates from both changes in the system design (e.g. two stage expansion) and components efficiency improvement (e.g. higher total efficiency of compressors - lower internal superheat and higher evaporation temperatures of cabinets). - Highlights: • Five Swedish supermarkets using three CO 2 refrigeration solutions are analyzed. • A trend of improvement in energy efficiency has been observed. • Parallel CO 2 system with indirect heat rejection offers the lowest energy efficiency. • CO 2 trans-critical booster with gas removal achieves up to 35% COP improvement

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

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.

Experimental study on a resorption system for power and refrigeration cogeneration

International Nuclear Information System (INIS)

Jiang, L.; Wang, L.W.; Liu, C.Z.; Wang, R.Z.

2016-01-01

Energy conversion technologies, especially for power generation and refrigeration technologies driven by the low temperature heat, are gathering the momentum recently. This paper presents a novel resorption system for electricity and refrigeration cogeneraion. Compared with adsorption refrigeration system, resorption refrigeration is characterized as safety and simple structure since there is no ammonia liquid in the system. The cogeneration system is mainly composed of three HTS (high temperature salt) unit beds; three LTS (low temperature salts) unit beds, one expander, three ammonia valves, two oil valves, four water valves and connection pipes. Chemical working pair of MnCl 2 –CaCl 2 –NH 3 is selected. Since scroll expander is suitable for small type power generation system, it is chosen for expansion process. 4.8 kg MnCl 2 and 3.9 kg CaCl 2 impregnated in expanded natural graphite treated with sulfuric acid (ENG-TSA) are filled in the cogeneration system. Experimental results show that maximum cooling power 2.98 kW is able to be obtained while maximum shaft power is about 253 W with 82.3 W average value. The cogeneration system can be utilized for the heat source temperature lower than 170 °C. Total energy efficiency increases from 0.293 to 0.417 then decreases to 0.407 while exergy efficiency increases from 0.12 to 0.16. - Highlights: • A resorption system for power and refrigeration cogeneration is established and investigated. • ENG-TSA as the additive improves the heat and mass performance of composite adsorbent. • The highest shaft power and refrigeration power are 253 W and 2.98 kW, respectively. • Total energy efficiency of the system increases from 0.293 to 0.417 then decreases to 0.407.

Simulation on a proposed large-scale liquid hydrogen plant using a multi-component refrigerant refrigeration system

Energy Technology Data Exchange (ETDEWEB)

Krasae-in, Songwut [Norwegian University of Science and Technology, Kolbjorn Hejes vei 1d, NO-7491 Trondheim (Norway); Stang, Jacob H.; Neksa, Petter [SINTEF Energy Research AS, Kolbjorn Hejes vei 1d, NO-7465 Trondheim (Norway)

2010-11-15

A proposed liquid hydrogen plant using a multi-component refrigerant (MR) refrigeration system is explained in this paper. A cycle that is capable of producing 100 tons of liquid hydrogen per day is simulated. The MR system can be used to cool feed normal hydrogen gas from 25 C to the equilibrium temperature of -193 C with a high efficiency. In addition, for the transition from the equilibrium temperature of the hydrogen gas from -193 C to -253 C, the new proposed four H{sub 2} Joule-Brayton cascade refrigeration system is recommended. The overall power consumption of the proposed plant is 5.35 kWh/kg{sub LH2}, with an ideal minimum of 2.89 kWh/kg{sub LH2}. The current plant in Ingolstadt is used as a reference, which has an energy consumption of 13.58 kWh/kg{sub LH2} and an efficiency of 21.28%: the efficiency of the proposed system is 54.02% or more, where this depends on the assumed efficiency values for the compressors and expanders. Moreover, the proposed system has some smaller-size heat exchangers, much smaller compressor motors, and smaller crankcase compressors. Thus, it could represent a plant with the lowest construction cost with respect to the amount of liquid hydrogen produced in comparison to today's plants, e.g., in Ingolstadt and Leuna. Therefore, the proposed system has many improvements that serve as an example for future hydrogen liquefaction plants. (author)

Cooling and heating facility for nuclear power plant

International Nuclear Information System (INIS)

Kakuta, Atsuro

1994-01-01

The present invention concerns a cooling and heating facility for a nuclear power plant. Namely, a cooling water supply system supplies cooling water prepared by a refrigerator for cooling the inside of the plant. A warm water supply system supplies warm water having its temperature elevated by using an exhausted heat from a reactor water cleanup system. The facility comprises a heat pump-type refrigerator disposed in a cold water supply system for producing cold water and warm water, and warm water pipelines for connecting the refrigerator and the warm water supply system. With such a constitution, when the exhaust heat from the reactor water cleanup system can not be used, warm water prepared by the heat pump type refrigerator is supplied to the warm water supply system by way of the warm water pipelines. Accordingly, when the exhaust heat from the reactor water cleanup system can not be used such as upon inspection of the plant, a portion of the refrigerators in a not-operated state can be used for heating. Supply of boiler steams in the plant is no more necessary or extremely reduced. (I.S.)

Commissioning of a 20 K Helium Refrigeration System for NASA-JSC Chamber A

Science.gov (United States)

Homan, J.; Redman, R.; Ganni, V.; Sidi-Yekhlef, A.; Knudsen, P.; Norton, R.; Lauterbach, J.; Linza, R.; Vargas, G.

2013-01-01

A new 20 K helium refrigerator installed at NASA Johnson Space Center s Space Environment Simulation Laboratory (SESL) was successfully commissioned and tested in 2012. The refrigerator is used to create a deep space environment within SESL s Chamber A to perform ground testing of the James Webb Space Telescope (JWST). The chamber previously and currently still has helium cryo-pumping panels (CPP) and liquid nitrogen shrouds used to create low earth orbit environments. Now with the new refrigerator and new helium shrouds the chamber can create a deep space environment. The process design, system analysis, specification development, and commissioning oversight were performed by the cryogenics department at Jefferson Lab, while the contracts and system installation was performed by the ESC group at JSC. Commissioning data indicate an inverse coefficient of performance better than 70 W/W for a 18 kW load at 20 K (accounting for liquid nitrogen pre-cooling power) that remains essentially constant down to one third of this load. Even at 10 percent of the maximum capacity, the performance is better than 150 W/W at 20 K. The refrigerator exceeded all design goals and demonstrated the ability to support a wide load range from 10 kW at 15 K to 100 kW at 100 K. The refrigerator is capable of operating at any load temperature from 15 K to ambient with tight temperature stability. The new shroud (36 tons of aluminum) can be cooled from room temperature to 20 K in 24 hours. This paper will outline the process design and commissioning results.

Design and Performance Analysis of a Biodiesel Engine Driven Refrigeration System for Vaccine Storage

Directory of Open Access Journals (Sweden)

K Kamsuk

2013-06-01

Full Text Available A compact, stand-alone, refrigeration module powered by a small biodiesel engine for vaccine storage in rural use was proposed. The engine was of single cylinder, four-stroke, directinjection with displacement of 0.296 cm3 and compression ratio of 20:1. The refrigeration system was modified from an automotive vapor compression system. The system performance was analytically investigated. From the simulation, it was found to have acceptable operation over a range of speeds and loads. Performance of the system in terms of fuel consumption and torque tended to decrease with an increase in engine speed. The modular system was able to operate at cooling loads above 4.6 kW, with proper speed ratio between the engine and the compressor. Overall, primary energy ratio of the refrigeration was found to be maximum at 0.54.

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.

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

Performance of a compact solar absorption cooling system

International Nuclear Information System (INIS)

Mulyanef; Kamaruzzaman Sopian

2006-01-01

This paper describes the performance of a compact solar absorption system. Purpose of compact solar is collector, generator and condenser in one unit. At present, two types of absorption cooling systems are marketed: the lithium bromide-water system and the ammonia-water system. In the lithium bromide-water system, water vapor is the refrigerant and ammonia water system where ammonia is the refrigerant. In addition, the ammonia-water system requires higher generator temperature 120 o C to 150 o C than a flat-plate solar collector can provide without special techniques. The lithium bromide-water system operates satisfactorily at a generator temperature of 75 o C to 100 o C, achievable by a flat-plate collector. The lithium bromide-water system also has a higher COP than the ammonia-water system. The disadvantage of the lithium bromide-water systems is that the evaporators cannot operate at temperature below 0 o C since the refrigerant is water. The Coefficient of Performance (COP) system is 0.62 and the concentration of LiBr-H 2 O is 50%

Thermodynamic analysis of a novel energy-efficient refrigeration system subcooled by liquid desiccant dehumidification and evaporation

International Nuclear Information System (INIS)

She, Xiaohui; Yin, Yonggao; Zhang, Xiaosong

2014-01-01

Highlights: • An energy-efficient refrigeration system with a novel subcooling method is proposed. • Thermodynamic analysis is conducted to discuss the effects of operation parameters. • Two different utilization ways of condensation heat are compared. • The system achieves much higher COP, even higher than reverse Carnot cycle. • Suggested mass concentration for LiCl–H 2 O is around 32% at a typical case. - Abstract: A new energy-efficient refrigeration system subcooled by liquid desiccant dehumidification and evaporation was proposed in this paper. In the system, liquid desiccant system could produce very dry air for an indirect evaporative cooler, which would subcool the vapor compression refrigeration system to get higher COP than conventional refrigeration system. The desiccant cooling system can use the condensation heat for the desiccant regeneration. Thermodynamic analysis is made to discuss the effects of operation parameters (condensing temperature, liquid desiccant concentration, ambient air temperature and relative humidity) on the system performance. Results show that the proposed hybrid vapor compression refrigeration system achieves significantly higher COP than conventional vapor compression refrigeration system, and even higher than the reverse Carnot cycle at the same operation conditions. The maximum COPs of the hybrid systems using hot air and ambient air are 18.8% and 16.3% higher than that of the conventional vapor compression refrigeration system under varied conditions, respectively

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

Thermodynamic, Environmental and Economic Analyses of Solar Ejector Refrigeration System Application for Cold Storage

Directory of Open Access Journals (Sweden)

İbrahim ÜÇGÜL

2009-02-01

Full Text Available The refrigeration processes have been widely applied for especially in cold storages. In these plants, the systems working with compressed vapour cooling cycles have been used as a classical method. In general, electrical energy is used for compressing in these processes. Although, mainly the electricity itself has no pollution effect on the environment, the fossil fuels that are widely used to produce electricity in the most of the world, affect the nature terribly. In short, these refrigeration plants, because of the source of the electricity pollute the nature indirectly. However, for compression an ejector refrigeration system requires one of the important renewable energy sources with negligible pollution impact on the environment, namely solar energy from a thermal source. Thermodynamical, environmental and economical aspects of the ejector refrigeration system working with solar energy was investigated in this study. As a pilot case, apple cold storage plants widely used in ISPARTA city, which 1/5 th of apple production of TURKEY has been provided from, was chosen. Enviromental and economical advantages of solar ejector refrigeration system application for cold storage dictated by thermodynamic, economic and enviromental analyses in this research.

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.

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.

Magnet/cryocooler integration for thermal stability in conduction-cooled systems

Science.gov (United States)

Chang, H.-M.; Kwon, K. B.

2002-05-01

The stability conditions that take into accounts the size of superconducting magnets and the refrigeration capacity of cryocoolers are investigated for the conduction-cooled systems without liquid cryogens. The worst scenario in the superconducting systems is that the heat generation in the resistive state exceeds the refrigeration, causing a rise in the temperature of the magnet winding and leading to burnout. It is shown by an analytical solution that in the continuously resistive state, the temperature may increase indefinitely or a stable steady state may be reached, depending upon the relative size of the magnet with respect to the refrigeration capacity of the cryocooler. The stability criteria include the temperature-dependent properties of the magnet materials and the refrigeration characteristics of the cryocooler. A useful graphical scheme is presented and the design of the stable magnet/cryocooler interface is demonstrated.

Central magnetic cooling and refrigeration machines (chiller) and their assessment. A feasibility study - Final report

Energy Technology Data Exchange (ETDEWEB)

Egolf, P. W.; Gonin, C. [University of Applied Sciences of Western Switzerland, HEIG-VD, Yverdon-les Bains (Switzerland); Kitanovski, A. [University of Ljubljana, Ljubljana (Slovenia)

2010-03-15

This final report for the Swiss Federal Office of Energy (SFOE) presents the results of a feasibility study made concerning magnetic cooling and refrigeration machines. This report presents a comprehensive thermodynamic and economic analysis of applications of rotary magnetic chillers. The study deals with magnetic chillers based on permanent magnets and superconducting magnets, respectively. The numerical design of permanent magnet assemblies with different magnetic flux densities is discussed. The authors note that superconducting magnetic chillers are feasible only in large-scale applications with over 1 MW of cooling power. This report describes new ideas for magnetic refrigeration technologies, which go beyond the state of the art. They show potential for a substantial reduction of costs and further improvements in efficiency. Rotary magnetic liquid chillers with 'wavy' structures and using micro tubes are discussed, as are superconducting magnetic chillers and future magneto-caloric technologies.

Development of a CO{sub 2} cooling system for the CBM silicon tracking system

Energy Technology Data Exchange (ETDEWEB)

Sanchez Rosado, Jorge; Degirmenciler, Burak; Heuser, Johann; Sturm, Christian [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH (Germany); Lymanets, Anton; Schmidt, Hans Rudolf [Eberhard Karls Universitaet Tuebingen (Germany)

2015-07-01

The demanding requirements of current high-energy physics experiments curiously bring back the idea of using a well-known and present refrigerant in nature: CO{sub 2}. As an outcome of previous studies and effort made within the current upgrade programs of detectors like ATLAS or CMS, this refrigerant is the optimum solution. Due to its highest volumetric heat transfer coefficient, it fulfills the requirements in this kind of detectors such as reduction of mass budget and the use of smaller diameter for cooling pipes. A two-phase (evaporative) CO{sub 2} cooling system is taken as the first choice to extract the 42 kW dissipated by the electronics of the Silicon Tracking System, the central detector of the CBM experiment at FAIR that will be installed in the gap of the 1 T super-conducting dipole magnet in a confined volume of 2 m{sup 3}. As a step towards the final design of this a cooling system, a 1 kW cooling unit called TRACI-XL was conceived at GSI in cooperation with CERN. This scaled prototype allows gaining insight into the behavior of the full system with valuable conclusions in terms of thermodynamics, process engineering and automation.

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.

Development of a hybrid refrigerator combining thermoelectric and vapor compression technologies

International Nuclear Information System (INIS)

Vian, J.G.; Astrain, D.

2009-01-01

A domestic refrigerator with three compartments has been developed: refrigerator compartment, at 4 deg. C (vapor compression cooling system); freezer compartment, at -22 deg. C (vapor compression cooling system); and a new super-conservation compartment, at 0 deg. C (thermoelectric cooling system). The thermoelectric system designed for the super-conservation compartment eliminates the oscillation of its temperature due to the start and stop compressor cycles, obtaining a constant temperature and thus, a better preservation of the food. For the design and optimization of this application, a computational model, based in the numerical method of finite differences, has been developed. This model allows to simulate the complete hybrid refrigerator (vapor compression-thermoelectricity). The accuracy of the model has been experimentally checked, with a maximum error of 1.2 deg. C for temperature values, and 8% for electric power consumption. By simulations with the computational model, the design of the refrigerator has been optimized, obtaining a final prototype highly competitive, by the features on food preservation and power consumption: 1.15 kW h per day (48.1 W) for an ambient temperature of 25 deg. C. According to European rules, this power consumption value means that this new refrigerator could be included on energy efficiency class B.

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.

A novel nuclear combined power and cooling system integrating high temperature gas-cooled reactor with ammonia–water cycle

International Nuclear Information System (INIS)

Luo, Chending; Zhao, Fuqiang; Zhang, Na

2014-01-01

Highlights: • We propose a novel nuclear ammonia–water power and cooling cogeneration system. • The high temperature reactor is inherently safe, with exhaust heat fully recovered. • The thermal performances are improved compared with nuclear combined cycle. • The base case attains an energy efficiency of 69.9% and exergy efficiency of 72.5%. • Energy conservation and emission reduction are achieved in this cogeneration way. - Abstract: A nuclear ammonia–water power and refrigeration cogeneration system (NAPR) has been proposed and analyzed in this paper. It consists of a closed high temperature gas-cooled reactor (HTGR) topping Brayton cycle and a modified ammonia water power/refrigeration combined bottoming cycle (APR). The HTGR is an inherently safe reactor, and thus could be stable, flexible and suitable for various energy supply situation, and its exhaust heat is fully recovered by the mixture of ammonia and water in the bottoming cycle. To reduce exergy losses and enhance outputs, the ammonia concentrations of the bottoming cycle working fluid are optimized in both power and refrigeration processes. With the HTGR of 200 MW thermal capacity and 900 °C/70 bar reactor-core-outlet helium, the system achieves 88.8 MW net electrical output and 9.27 MW refrigeration capacity, and also attains an energy efficiency of 69.9% and exergy efficiency of 72.5%, which are higher by 5.3%-points and 2.6%-points as compared with the nuclear combined cycle (NCC, like a conventional gas/steam power-only combined cycle while the topping cycle is a closed HTGR Brayton cycle) with the same nuclear energy input. Compared with conventional separate power and refrigeration generation systems, the fossil fuel saving (based on CH 4 ) and CO 2 emission reduction of base-case NAPR could reach ∼9.66 × 10 4 t/y and ∼26.6 × 10 4 t/y, respectively. The system integration accomplishes the safe and high-efficiency utilization of nuclear energy by power and refrigeration

The 4.5K refrigerators for the LHC are all present and correct!

CERN Document Server

2004-01-01

Acceptance procedures for the last of the LHC 4.5 K refrigerators have been completed at Point 6. All that now remains to be done, to have the LHC refrigeration system ready by the end of 2005, is to upgrade the refrigerators recovered from LEP and install the 1.8 K cooling system. By now you will be well aware that the LHC's superconducting magnets cannot operate unless they are cooled to 1.8 K (-271°C) (see Bulletin 13-14/2002). Eight 4.5 K refrigerators, one for each sector of the LHC, are required to achieve this. In December last year the last of these refrigerators, specially designed for the LHC, was accepted at Point 6. "It is a big step forwards for the LHC's refrigeration system, as it takes its cooling capacity at 4.5 K to 140 kW, that is to say almost 40,000 litres of liquid helium per hour, a capacity never previously attained. The progress achieved since the days of LEP is impressive, particularly if one bears in mind the extent of the infrastructure required, " (see...

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

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.

Data-Driven Control of Refrigeration System

DEFF Research Database (Denmark)

Vinther, Kasper

Refrigeration is used in a wide range of applications, e.g., for storage of food at low temperatures to prolong shelf life and in air conditioning for occupancy comfort. The main focus of this thesis is control of supermarket refrigeration systems. This market is very competitive and it is import......Refrigeration is used in a wide range of applications, e.g., for storage of food at low temperatures to prolong shelf life and in air conditioning for occupancy comfort. The main focus of this thesis is control of supermarket refrigeration systems. This market is very competitive...... traditionally are a pressure and a temperature sensor. In this thesis, a novel maximum slope-seeking (MSS) control method is developed. This has resulted in a control implementation, which successfully has been able to control the evaporator superheat in four widely different refrigeration system test...... problems. The method utilizes the qualitative nonlinearity in the system and harmonic analysis of a perturbation signal to reach an unknown, but suitable, operating point. Another important control task in refrigeration systems is to maintain the temperature of the refrigerated space or foodstuff within...

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.

Thermodynamic analysis and theoretical study of a continuous operation solar-powered adsorption refrigeration system

International Nuclear Information System (INIS)

Hassan, H.Z.; Mohamad, A.A.

2013-01-01

Due to the intermittent nature of the solar radiation, the day-long continuous production of cold is a challenge for solar-driven adsorption cooling systems. In the present study, a developed solar-powered adsorption cooling system is introduced. The proposed system is able to produce cold continuously along the 24-h of the day. The theoretical thermodynamic operating cycle of the system is based on adsorption at constant temperature. Both the cooling system operating procedure as well as the theoretical thermodynamic cycle are described and explained. Moreover, a steady state differential thermodynamic analysis is performed for all components and processes of the introduced system. The analysis is based on the energy conservation principle and the equilibrium dynamics of the adsorption and desorption processes. The Dubinin–Astakhov adsorption equilibrium equation is used in this analysis. Furthermore, the thermodynamic properties of the refrigerant are calculated from its equation of state. The case studied represents a water chiller which uses activated carbon–methanol as the working pair. The chiller is found to produce a daily mass of 2.63 kg cold water at 0 °C from water at 25 °C per kg of adsorbent. Moreover, the proposed system attains a cooling coefficient of performance of 0.66. - Highlights: • A new continuous operation solar-driven adsorption refrigeration system is introduced. • The theoretical thermodynamic cycle is presented and explained. • A complete thermodynamic analysis is performed for all components and processes of the system. • Activated carbon–methanol is used as the working pair in the case study

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.

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

A new compressed air energy storage refrigeration system

International Nuclear Information System (INIS)

Wang Shenglong; Chen Guangming; Fang Ming; Wang Qin

2006-01-01

In this study, a new compressed air energy storage (CAES) refrigeration system is proposed for electrical power load shifting application. It is a combination of a gas refrigeration cycle and a vapor compression refrigeration cycle. Thermodynamic calculations are conducted to investigate the performance of this system. Economic analysis is performed to study the operating cost of the system, and comparison is made with a vapor compression refrigeration system and an ice storage refrigeration system. The results indicate that the CAES refrigeration system has the advantages of simple structure, high efficiency and low operating cost

20 K Helium Refrigeration System for NASA-JSC Chamber-A

Science.gov (United States)

Homan, J.; Redman, R.; Ganni, V.; Sidi-Yekhelef, A.; Knudsen, P.; Norton, R.; Lauterbach, J.; Linza, R.; Vargas, G.

2013-01-01

A new 20 K helium refrigerator installed at NASA Johnson Space Center's Space Environment Simulation Laboratory (SESL) was successfully commissioned and tested in 2012. The refrigerator is used to create a deep space environment within SESL s Chamber A to perform ground testing of the James Webb Space Telescope. The chamber previously and currently still has helium cryopumping panels (CPP) and LN2 shrouds used to create Low Earth Orbit environments. Now with the new refrigerator and new helium shrouds (45 x 65 ) the chamber can create a deep space environment. The process design, system analysis, specification development, and commissioning oversight were performed by the cryogenics department at Jefferson Labs, while the contracts and system installation was performed by the ESC group at JSC. Commissioning data indicate a inverse coefficient of performance better than 70 W/W for a 18 KW load at 20 K (accounting for liquid nitrogen precooling power) that remains essentially constant down to 1/3 of this load. Even at 10 percent of the maximum capacity, the performance is better than 140 W/W at 20K. The refrigerator exceeded all design goals and demonstrated the ability to support a wide load range from 10kW at 15 K to 100 kW at 100K. The refrigerator is capable of operating at any load temperature from 15K to ambient with tight temperature stability. The new shroud (36 tons of aluminum) can be cooled from room temperature to 20 K in 24 hours. This paper will outline the process design and commissioning results.

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

Applicability of ASST-A helium refrigeration system for JLab End Station Refrigerator

Science.gov (United States)

Hasan, N.; Knudsen, P.; Ganni, V.

2017-12-01

The MØLLER experiment at Jefferson Lab (JLab) is a high power (5 kW) liquid hydrogen target scheduled to be operational in the 12 GeV-era. At present, cryogenic loads and targets at three of JLab’s four experimental halls are supported by the End Station Refrigerator (ESR) - a CTI/Helix 1.5 kW 4.5 K refrigerator. It is not capable of supporting the high power target load and a capacity upgrade of the ESR cryogenic system is essential. The ASST-A helium refrigeration system is a 4 kW 4.5 K refrigerator. It was designed and used for the Superconducting Super Collider Lab (SSCL) magnet string test and later obtained by JLab after the cancellation of that project. The modified ASST-A refrigeration system, which will be called ESR-II along with a support flow from JLab’s Central Helium Liquefier (CHL) is considered as an option for the End Station Refrigerator capacity upgrade. The applicability of this system for ESR-II under varying load conditions is investigated. The present paper outlines the findings of this process study.

ENERGY EFFICIENCY, ENERGY SAVING POTENTIAL AND ENVIRONMENTAL IMPACT RESEARCH OF LPG CARRIER REFRIGERATION SYSTEM

Directory of Open Access Journals (Sweden)

V. О. Bedrosov

2016-12-01

Full Text Available Nowadays energy efficiency improvement and global warming are issues of current interest because of the natural resources depletion and extreme climate change. Thus, the problem of formation of strict regulations regarding emissions into the air arises. This paper presents the study of cascade refrigeration system for re-condensing of associated petroleum gas during sea transportation for LPG carrier. The structural optimization has been performed. LPG gas carriers with 266 000 m3 ethane capacity require 15 MW cascade refrigeration system for re-condensing if the temperature in the coastal LPG storage is -70°C, and the temperature for transported Ethan is maintained at  -75°C. For current storage conditions the required system cooling capacity is only 1,078 MW intended for the heat gain rejection from the environment during Ethane transportation. The replacement of ozone-depleting refrigerant R22 to alternative agents: R407C, R404A, R402A, R717, R290, R1270 was estimated. The results of analysis have shown that the proposed improvements can be used to optimize the LPG carrier cascade refrigeration system

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.

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.

Experimental evaluation of SWCNT-water nanofluid as a secondary fluid in a refrigeration system

International Nuclear Information System (INIS)

Vasconcelos, Adriano Akel; Cárdenas Gómez, Abdul Orlando; Bandarra Filho, Enio Pedone; Parise, José Alberto Reis

2017-01-01

Highlights: • SWCNT-water nanofluid was used as secondary fluid for a refrigeration system. • For a given HTFS mass flow rate and inlet temperature, nanofluid performed better than base fluid. • Total power consumption was not significantly affected by volume concentration. • Nanoparticle volume fraction ranged from 0 to 0.21%. - Abstract: SWCNT-water (single walled carbon nanotube) nanofluid was tested as a secondary fluid for a 4–9 kW indirect vapor compression refrigeration system. The evaporator, with boiling refrigerant HCFC-22 extracting heat from the nanofluid, was of the brazed plate counter-flow type. A semi-hermetic compressor, an electronic expansion valve (EEV) and an air-cooled condenser were the other main components of the refrigeration cycle. Tests were carried out with the experimental apparatus operating over a range of different volumetric fractions of nanoparticles (0–0.21%) as well as nanofluid inlet temperatures (30–40 °C) and mass flow rates (40–80 g/s). Overall, the performance of the system working with nanofluid as a secondary fluid was superior to that where just the base fluid (i.e., pure water) circulated in the secondary fluid loop, at the same mass flow rate and inlet temperature. The enhanced thermal conductivity of the nanofluid is believed to be the main reason why the refrigeration system with the nanofluid loop, if compared to that with pure water, presented a higher refrigerating capacity.

Novel materials for laser refrigeration

Energy Technology Data Exchange (ETDEWEB)

Hehlen, Markus P [Los Alamos National Laboratory

2009-01-01

The status of optical refrigeration of rare-earth-doped solids is reviewed, and the various factors that limit the performance of current laser-cooling materials are discussed. Efficient optical refrigeration is possible in materials for which {Dirac_h}{omega}{sub max} < E{sub p}/8, where {Dirac_h}{omega}{sub max} is the maximum phonon energy of the host material and E{sub p} is the pump energy of the rare-earth dopant. Transition-metal and OH{sup -}impurities at levels >100 ppb are believed to be the main factors for the limited laser-cooling performance in current materials. The many components of doped ZBLAN glass pose particular processing challenges. Binary fluoride glasses such as YF{sub 3}-LiF are considered as alternatives to ZBLAN. The crystalline system KPb{sub 2}CI{sub 5} :Dy{sup 3+} is identified as a prime candidate for high-efficiency laser cooling.

Optimisation of expansion liquefaction processes using mixed refrigerant N_2–CH_4

International Nuclear Information System (INIS)

Ding, He; Sun, Heng; He, Ming

2016-01-01

Highlights: • A refrigerant composition matching method for N_2–CH_4 expansion processes. • Efficiency improvements for propane pre-cooled N_2–CH_4 expansion processes. • The process shows good adaptability to varying natural gas compositions. - Abstract: An expansion process with a pre-cooling system is simulated and optimised by Aspen HYSYS and MATLAB"™. Taking advantage of higher specific refrigeration effect of methane and easily reduced refrigeration temperature of nitrogen, the designed process adopts N_2–CH_4 as a mixed refrigerant. Based on the different thermodynamic properties and sensitivity difference of N_2 and CH_4 over the same heat transfer temperature range, this work proposes a novel method of matching refrigerant composition which aims at single-stage or multi-stage series expansion liquefaction processes with pre-cooling systems. This novel method is applied successfully in propane pre-cooled N_2–CH_4 expansion process, and the unit power consumption is reduced to 7.09 kWh/kmol, which is only 5.35% higher than the global optimised solutions obtained by genetic algorithm. This novel method can fulfil the accomplishments of low energy consumption and high liquefaction rate, and thus decreases the gap between the mixed refrigerant and expansion processes in energy consumption. Furthermore, the high exergy efficiency of the process indicates good adaptability to varying natural gas compositions.

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.

Advanced refrigeration system for the Brookhaven superconducting cable project

International Nuclear Information System (INIS)

Jensen, J.E.

1975-01-01

A description is given of a basic supercritical refrigerator. The present status of the cable enclosure and the types of cooling schemes being considered are presented with some examples of laboratory results and computer analysis. (MOW)

Synchronous compartment temperature control and apparatus for refrigeration with reduced energy consumption

Science.gov (United States)

Gomes, Alberto Regio; Keres, Stephen L.; Kuehl, Stephen J.; Litch, Andrew D.; Richmond, Peter J.; Wu, Guolian

2015-09-22

A refrigerator appliance configuration, and associated methods of operation, for an appliance with a controller, a condenser, at least one evaporator, a compressor, and two refrigeration compartments. The configuration may be equipped with a variable-speed or variable-capacity compressor, variable speed evaporator or compartment fans, a damper and/or a dual-temperature evaporator with a valve system to control flow of refrigerant through one or more pressure reduction devices. The controller, by operation of the compressor, fans, damper and/or valve system, depending on the appliance configuration, controls the cooling rate in one or both compartments to synchronize, alternating cycles of cooling the compartments to their set point temperatures.

On the conceptual design of pre-cooling stage of LNG plants using propane or an ethane/propane mixture

International Nuclear Information System (INIS)

Castillo, L.; Dorao, C.A.

2013-01-01

Highlights: ► LNG technologies are differentiated by heat exchanger type, compressor/driver, refrigerant type and others. ► The design of the pre-cooling system on the LNG technologies should start by compressor definition. ► Thermodynamically, pre-cooling based on a C3 has higher advantages than C 2 /C 3 mixed refrigerant cycle. ► The pre-cooling system needs to consider aspects: equipment number, costs, plot area, safety. ► A proper model is required for selection of the pre-cooling, including all aspects that could affect the costs. - Abstract: Today, LNG technologies are based on pure and mixed refrigerants cycles on the pre-cooling system, but the advantages and disadvantages of considering a mixed refrigerant or pure refrigerant cycle in the pre-cooling stage is not well understood. In this work an analysis of the compressors and the refrigerants in the pre-cooling system is carried out. The most relevant aspect of the evaluation is to establish some thermodynamical criteria for the selecting of the suitable refrigerant for the pre-cooling stage. For final decision-making process of the selection of the pre-cooling stage, a proper model is required which should take into account all aspects that could affect the capital and operation costs.

Fault diagnosis and refrigerant leak detection in vapour compression refrigeration systems

Energy Technology Data Exchange (ETDEWEB)

Tassou, S.A.; Grace, I.N. [Brunel University, Uxbridge (United Kingdom). Department of Mechanical Engineering

2005-08-01

The environmental impact of refrigeration systems can be reduced by operation at higher efficiency and reduction of refrigerant leakage. Refrigerant loss contributes both directly and indirectly to global warming through inefficient system operation, increased power consumption and greenhouse gas emissions and higher maintenance costs. Existing sensor-based leak detection methods are limited by the inability to detect gradual leakage and the need for careful sensor location. There is a requirement for a real-time performance monitoring approach to leak detection and fault diagnosis which overcomes these disadvantages. This paper reports on the development of a fault diagnosis and refrigerant leak detection system based on artificial intelligence and real-time performance monitoring. The system has been used successfully to distinguish between faulty and fault free operation, steady-state and transient operation, leakage and over charge conditions. Work currently underway is aimed at testing additional fault conditions and establishing further rules to distinguish between these patterns. (author)

Alkali Metal Backup Cooling for Stirling Systems - Experimental Results

Science.gov (United States)

Schwendeman, Carl; Tarau, Calin; Anderson, William G.; Cornell, Peggy A.

2013-01-01

In a Stirling Radioisotope Power System (RPS), heat must be continuously removed from the General Purpose Heat Source (GPHS) modules to maintain the modules and surrounding insulation at acceptable temperatures. The Stirling convertor normally provides this cooling. If the Stirling convertor stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS at the cost of an early termination of the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) can be used to passively allow multiple stops and restarts of the Stirling convertor. In a previous NASA SBIR Program, Advanced Cooling Technologies, Inc. (ACT) developed a series of sodium VCHPs as backup cooling systems for Stirling RPS. The operation of these VCHPs was demonstrated using Stirling heater head simulators and GPHS simulators. In the most recent effort, a sodium VCHP with a stainless steel envelope was designed, fabricated and tested at NASA Glenn Research Center (GRC) with a Stirling convertor for two concepts; one for the Advanced Stirling Radioisotope Generator (ASRG) back up cooling system and one for the Long-lived Venus Lander thermal management system. The VCHP is designed to activate and remove heat from the stopped convertor at a 19 degC temperature increase from the nominal vapor temperature. The 19 degC temperature increase from nominal is low enough to avoid risking standard ASRG operation and spoiling of the Multi-Layer Insulation (MLI). In addition, the same backup cooling system can be applied to the Stirling convertor used for the refrigeration system of the Long-lived Venus Lander. The VCHP will allow the refrigeration system to: 1) rest during transit at a lower temperature than nominal; 2) pre-cool the modules to an even lower temperature before the entry in Venus atmosphere; 3) work at nominal temperature on Venus surface; 4) briefly stop multiple times on the Venus surface to allow scientific measurements. This paper presents the experimental

CFC environmental problems and cooling technology

International Nuclear Information System (INIS)

Hornung, M.O.

1991-08-01

The aim of the report is to provide a broad survey of the technological problems imposed on the production of cooling systems by the demands for reduction in the use of chlorofluorocarbons as refrigerants. With regard to industrial research in this area the present situation is clarified and possible future developments are discussed. The influence of CFC gasses on the global environment and international and national legislation within this field are explained. Alternative refrigerants and cooling processes, and ways of reducing refrigerant leakage, are described. It is concluded that currently the use of alternative refrigerants is the policy which is generally accepted, and intensive research is being carried out in this field. R134a should substitute R12 in the cases of household refrigerators and air conditioning, and will soon be commercially available. The use of R22 and ammonia will be extended. This is a practical policy to follow up commercially, whereas the policy of alternative processes presents more problems because they are not so developed and there is less available know-how in this area. The possibilities for hermetic sealing of cooling systems are unrealistic and should anyway be regarded only as a supplement to alternative refrigerants. Within the European Community it is intended to provide standards and regulations in relation to air pollution from refrigerants. (AB) (58 refs.)

Performance measurement of a mini thermoacoustic refrigerator and associated drivers

OpenAIRE

Petrina, Denys E.

2002-01-01

Approved for public release; distribution is unlimited A miniature Thermoacoustic refrigerator is being developed to cool integrated circuits - which must sometimes operate at high temperatures nearing the upper threshold of their tolerance - to temperature spans more within the circuits' tolerable limits, without the need of the chemicals of a traditional refrigerating system. The development of an electrically powered acoustic driver that powers the thermoacoustic refrigerator is describ...

Structure optimization and performance experiments of a solar-powered finned-tube adsorption refrigeration system

International Nuclear Information System (INIS)

Ji, Xu; Li, Ming; Fan, Jieqing; Zhang, Peng; Luo, Bin; Wang, Liuling

2014-01-01

Highlights: • New-structure finned-tube adsorption bed for enhancing heat and mass transfer. • Temperatures on different parts of the adsorption tubes differ little. • Maximum COP of 0.122 and maximum daily ice-making of 6.5 kg are achieved by experiments. • Cooling efficiency of system with valve control higher than that without valve control. - Abstract: A large-diameter aluminum-alloy finned-tube absorbent bed collector was designed and optimized by enhancing the heat and mass transfer in the collector. The collection efficiency of the adsorbent bed collector was between 31.64% and 42.7%, and the temperature distribution in the absorbent bed was relatively uniform, beneficial to adsorption/desorption of the adsorbate in the absorbent bed. A solar-powered solid adsorption refrigeration system with the finned-tube absorbent bed collector was built. Some experiments corresponding to the adsorption/desorption process with and without a valve control were conducted in four typical weather conditions: sunny with clear sky, sunny with partly cloudy sky, cloudy sky and overcast sky. Activated carbon–methanol was utilized as the working pair for adsorption refrigeration in the experiments. The experiments achieved the maximum COP of 0.122 and the maximum daily ice-making of 6.5 kg. Under the weather conditions of sunny with clear sky, sunny with partly cloudy sky, and cloudy sky, ice-making phenomenon were observed. Even in the overcast-sky weather condition, the cooling efficiency of the system still reached 0.039 when the total solar radiation was 11.51 MJ. The cooling efficiency of the solar-powered adsorption refrigeration system with a valve control in the adsorption/desorption process was significantly higher than that without a valve control

Parametric analysis of an irreversible proton exchange membrane fuel cell/absorption refrigerator hybrid system

International Nuclear Information System (INIS)

Yang, Puqing; Zhang, Houcheng

2015-01-01

A hybrid system mainly consisting of a PEMFC (proton exchange membrane fuel cell) and an absorption refrigerator is proposed, where the PEMFC directly converts the chemical energy contained in the hydrogen into electrical and thermal energies, and the thermal energy is transferred to drive the bottoming absorption refrigerator for cooling purpose. By considering the existing irreversible losses in the hybrid system, the operating current density region of the PEMFC permits the absorption refrigerator to exert its function is determined and the analytical expressions for the equivalent power output and efficiency of the hybrid system under different operating conditions are specified. Numerical calculations show that the equivalent maximum power density and the corresponding efficiency of the hybrid system can be respectively increased by 5.3% and 6.8% compared to that of the stand-alone PEMFC. Comprehensive parametric analyses are conducted to reveal the effects of the internal irreversibility of the absorption refrigerator, operating current density, operating temperature and operating pressure of the PEMFC, and some integrated parameters related to the thermodynamic losses on the performance of the hybrid system. The model presented in the paper is more general than previous study, and the results for some special cases can be directly derived from this paper. - Highlights: • A CHP system composed of a PEMFC and an absorption refrigerator is proposed. • Current density region enables the absorption refrigerator to work is determined. • Multiple irreversible losses in the system are analytically characterized. • Maximum power density and corresponding efficiency can be increased by 5.3% and 6.8%. • Effects of some designing and operating parameters on the performance are discussed

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.)

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

Air-cooled recirculation cooling systems. Technical and economic comparison; Luftgekuehlte Rueckkuehlsysteme. Technisch wirtschaftlicher Vergleich

Energy Technology Data Exchange (ETDEWEB)

Dierks, G. [Fa. Jaeggi/Guentner (Schweiz) AG, Trimbach (Switzerland)

2000-03-01

There are several air-cooled forced-circulation cooling systems for heat removal from refrigeration systems. Optimum solutions should not be selected on the basis of the cost factor alone; an integrative approach should be used instead. An exemplary investigation is presented. [German] Fuer die Waermeabfuhr aus kaeltetechnischen Anlagen stehen verschiedene luftgekuehlte, zwangsbelueftete Rueckkuehlsysteme zur Verfuegung. Die Auswahl des Systems ist oft von kurzfristigem Kostendenken gepraegt, was in technischer und wirtschaftlicher Hinsicht aber nicht immer der optimalen Loesung entspricht. Erst die genauere Kenntnis der verschiedenen Systeme und eine ganzheitliche Betrachtungsweise ermoeglichen die optimale Wahl fuer den einzelnen Fall. Die hier praesentierte Untersuchung wird anhand eines konkreten Falls dargestellt, wobei Preise und technische Produktdaten auf realen Anfragen beruhen. Der Autor ist um objetive Bewertung bemueht, der Leser moege aber selbst urteilen. (orig./AKF)

Temperature stability limits for an isothermal demagnetization refrigerator

Science.gov (United States)

Kittel, P.

1984-01-01

It is pointed out that magnetic refrigeration can provide additional cooling for infrared detectors on space missions, taking into account the Shuttle Infrared Telescope Facility (SIRTF) and the Large Deployable Reflector (LDR). From a temperature of 2 K provided by the primary cryogens, magnetic refrigerators could cool bolometers or pumped photoconductors to 0.1 K or below. Such a reduction in operating temperature would increase the sensitivity for bolometers, while the response at longer wavelengths for pumped photoconductors would be improved. Two types of magnetic refrigeration cycles have been proposed. One type uses a complete demagnetization. The present investigation is concerned with the second type, which uses a feedback-controlled isothermal demagnetization, taking into account the temperature stability limits. Attention is given to control system resolution, thermometer noise, reaction time, and thermal time constants.

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.

Redesign 3 R Machine as a Refrigerant Waste Treatment Alternative in Environmental Rescue

Science.gov (United States)

Negara, I. P. S.; Arsawan, I. M.

2018-01-01

Cooling machine technologies really affect nowadays’ modern life, not only limited in enhancement of life quality and comfort, but it has also reached the essential things of humans’ life supporter (Arora, 2001). Cooling machine technologies have direct contribution toward environmental damage such as depletion of ozone layer and global warming through synthetic refrigerant waste and leakage (CFC and HFC) to environment. The refrigerant release to the environment is 60% of the service sector. Destructive characteristics of ozone possessed by CFC were first proposed by Rowland and Molina which were then supported by yard measurement. It is estimated that ozone layer damage occurs for about 3% every decade. The ozone layer located in the stratosphere is functioned to prevent ultraviolet-B ray from entering into earth surface. This Ultraviolet-B is suspected to be the cause of health problem for humans and disorder for plants on earth. As for the purpose of this research is to obtain a product design of refrigerant waste processing system (recovery and recycle refrigerant) as well as to acknowledge the work method (COP) of cooling machines that use CFC refrigerant (R-12) as the result of recovery and recycle compared to CFC refrigerant (R-12)/pure R134a. One method that can be used is by redesigning existing equipment namely 3R machine that cannot be used anymore thus it can be reused. This research will be conducted through modifying the existing 3R machine therefore it can be reused and be easily operated as well as doing the maintenance, after that the refrigerant as the result of recovery will be tried on a refrigeration system and a test of refrigeration system work method will be conducted by using the refrigerant recycle product which is obtained and compared with the work method of the one with pure refrigeration.The result has been achieved that the redesign product of refrigerant waste processing equipment can be reused and able to perform the recovery

Experimental Assessment of residential split type air-conditioning systems using alternative refrigerants to R-22 at high ambient temperatures

International Nuclear Information System (INIS)

Joudi, Khalid A.; Al-Amir, Qusay R.

2014-01-01

Highlights: • R290, R407C and R410A in residential split A/C units at high ambient. • 1 and 2 TR residential air conditioners with R22 alternatives at high ambient. • Residential split unit performance at ambients up to 55 °C with R22 alternatives. - Abstract: Steady state performance of residential air conditioning systems using R22 and alternatives R290, R407C, R410A, at high ambient temperatures, have been investigated experimentally. System performance parameters such as optimum refrigerant charge, coefficient of performance, cooling capacity, power consumption, pressure ratio, power per ton of refrigeration and TEWI environmental factor have been determined. All refrigerants were tested in the cooling mode operation under high ambient air temperatures, up to 55 °C, to determine their suitability. Two split type air conditioner of 1 and 2 TR capacities were used. A psychrometric test facility was constructed consisting of a conditioned cool compartment and an environmental duct serving the condenser. Air inside the conditioned compartment was maintained at 25 °C dry bulb and 19 °C wet bulb for all tests. In the environmental duct, the ambient air temperature was varied from 35 °C to 55 °C in 5 °C increments. The study showed that R290 is the better candidate to replace R22 under high ambient air temperatures. It has lower TEWI values and a better coefficient of performance than the other refrigerants tested. It is suitable as a drop-in refrigerant. R407C has the closest performance to R22, followed by R410A

Experimental study of hybrid interface cooling system using air ventilation and nanofluid

Science.gov (United States)

Rani, M. F. H.; Razlan, Z. M.; Bakar, S. A.; Desa, H.; Wan, W. K.; Ibrahim, I.; Kamarrudin, N. S.; Bin-Abdun, Nazih A.

2017-09-01

The hybrid interface cooling system needs to be established to chill the battery compartment of electric car and maintained its ambient temperature inside the compartment between 25°C to 35°C. The air cooling experiment has been conducted to verify the cooling capacity, compressor displacement volume, dehumidifying value and mass flow rate of refrigerant (R-410A). At the same time, liquid cooling system is analysed theoretically by comparing the performance of two types of nanofluid, i.e., CuO + Water and Al2O3 + Water, based on the heat load generated inside the compartment. In order for the result obtained to be valid and reliable, several assumptions are considered during the experimental and theoretical analysis. Results show that the efficiency of the hybrid interface cooling system is improved as compared to the individual cooling system.

A multi-stage traveling-wave thermoacoustically-driven refrigeration system operating at liquefied natural gas temperature

Science.gov (United States)

Luo, K.; Sun, D. M.; Zhang, J.; Shen, Q.; Zhang, N.

2017-12-01

This study proposes a multi-stage travelling-wave thermoacoustically refrigeration system (TAD-RS) operating at liquefied natural gas temperature, which consists of two thermoacoustic engines (TAE) and one thermoacoustic refrigerator (TAR) in a closed-loop configuration. Three thermoacoustic units connect each other through a resonance tube of small cross-sectional area, achieving “self-matching” for efficient thermoacoustic conversion. Based on the linear thermoacoustic theory, a model of the proposed system has been built by using DeltaEC program to show the acoustic field characteristics and performance. It is shown that with pressurized 5 MPa helium as working gas, the TAEs are able to build a stable and strong acoustic field with a frequency of about 85 Hz. When hot end temperature reaches 923 K, this system can provide about 1410 W cooling power at 110 K with an overall exergy efficiency of 15.5%. This study indicates a great application prospect of TAD-RS in the field of natural gas liquefaction with a large cooling capacity and simple structure.

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, ...

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.

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.

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

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.

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.

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.

Materials for Room Temperature Magnetic Refrigeration

DEFF Research Database (Denmark)

Hansen, Britt Rosendahl

Magnetic refrigeration is a cooling method, which holds the promise of being cleaner and more efficient than conventional vapor-compression cooling. Much research has been done during the last two decades on various magnetic materials for this purpose and today a number of materials are considered...... candidates as they fulfill many of the requirements for a magnetic refrigerant. However, no one material stands out and the field is still active with improving the known materials and in the search for a better one. Magnetic cooling is based on the magnetocaloric effect, which causes a magnetic material...... to change its temperature when a magnetic field is applied or removed. For room temperature cooling, one utilizes that the magnetocaloric effect peaks near magnetic phase transitions and so the materials of interest all have a critical temperature within the range of 250 – 310 K. A magnetic refrigerant...

Optimization of a cascade refrigeration system using refrigerant C_3H_8 in high temperature circuits (HTC) and a mixture of C_2H_6/CO_2 in low temperature circuits (LTC)

International Nuclear Information System (INIS)

Nasruddin; Sholahudin, S.; Giannetti, N.; Arnas

2016-01-01

Highlights: • Multi-objective optimization is conducted in the cascade refrigeration system. • Combination of operating temperature and refrigerant performance has been studied. • Characteristic of C_3H_8 and a mixture of C_2H_6/CO_2 have been investigated. • Determining of CO_2 fraction to optimize refrigeration system has been done. - Abstract: This paper discusses the multi-objectives optimization of a cascade refrigeration system using refrigerant C_3H_8 in high temperature circuits (HTC) and a mixture of C_2H_6/CO_2 in low temperature circuits (LTC). The evaporator temperature, condenser temperature, C_2H_6/CO_2 mixture condensation temperature, cascade temperature differences, and the CO_2 mass fraction are chosen as the decision variables. Whereas cooling capacity, cold space temperature, and ambient temperature are taken as the constraints. The purpose of this research is to design a cascade refrigeration system whose optimum performance are defined in terms of economics and thermodynamics. Accordingly, there are two objective functions that should be simultaneously optimized including the total annual cost which consists of the capital and operational cost and the total exergy destruction of the system. To this aim, the optimum operating temperature of the system and CO_2 fraction should be determined so that the system has minimum exergy destruction and annual cost. Results show that, the optimum value of the decision variables for this system can be determined by trade-off between annual cost and exergy destruction.

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.

Performance Assessment and Active System Monitoring for Refrigeration Systems

DEFF Research Database (Denmark)

Green, Torben

to the refrigeration system, is to optimise the total cost of ownership, (TCO). However, directly measuring TCO provides some challenges. It can therefore be beneficial to divide TCO into performance criteria, which can be quantied and measured. For supermarket refrigeration systems the performance criteria can...... is measure by the switch frequency of the compressors in the refrigeration system. The reason is that excessive compressor switching will wear down the compressors too fast and thereby decrease the reliability of the system due to a higher demand for maintenance. The proposed performance function provides...

Control Methods for Energy Management of Refrigeration Systems

DEFF Research Database (Denmark)

Shafiei, Seyed Ehsan

is decreased as the method does not need an explicit model of the system and, at the same time, the desired load following performance is attained. Recent research findings indicate that the refrigeration system commonly employed in food transportation can account for 40% of the total greenhouse gas emissions...... from the corresponding vehicle engines. Finally, the problem of optimization of a hybrid transport refrigeration system is addressed here. The hybrid refrigeration system is made by the integration of conventional refrigeration technology with thermal energy storage devices....

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.

Performance improvement of air-cooled refrigeration system by using evaporatively cooled air condenser

Energy Technology Data Exchange (ETDEWEB)

Hajidavalloo, E.; Eghtedari, H. [Mechanical Engineering Department, Shahid Chamran University, Golestan St., Ahvaz (Iran)

2010-08-15

Increasing the coefficient of performance of air conditioner with air-cooled condenser is a challenging problem especially in area with very hot weather conditions. Application of evaporatively cooled air condenser instead of air-cooled condenser is proposed in this paper as an efficient way to solve the problem. An evaporative cooler was built and coupled to the existing air-cooled condenser of a split-air-conditioner in order to measure its effect on the cycle performance under various ambient air temperatures up to 49 C. Experimental results show that application of evaporatively cooled air condenser has significant effect on the performance improvement of the cycle and the rate of improvement is increased as ambient air temperature increases. It is also found that by using evaporatively cooled air condenser in hot weather conditions, the power consumption can be reduced up to 20% and the coefficient of performance can be improved around 50%. More improvements can be expected if a more efficient evaporative cooler is used. (author)

Cooling concepts for HTS components

International Nuclear Information System (INIS)

Binneberg, A.; Buschmann, H.; Neubert, J.

1993-01-01

HTS components require that low-cost, reliable cooling systems be used. There are no general solutions to such systems. Any cooling concept has to be tailored to the specific requirements of a system. The following has to he taken into consideration when designing cooling concepts: - cooling temperature - constancy and controllability of the cooling temperature - cooling load and refrigerating capacity - continuous or discontinuous mode - degree of automation - full serviceability or availability before evacuation -malfunctions caused by microphonic, thermal or electromagnetic effects -stationary or mobile application - investment and operating costs (orig.)

Thermodynamic performance analysis of a vapor compression–absorption cascaded refrigeration system

International Nuclear Information System (INIS)

Jain, Vaibhav; Kachhwaha, S.S.; Sachdeva, Gulshan

2013-01-01

Highlights: • Study includes first and second law analysis with alternatives refrigerants. • Power consumption in cascaded system is 61% less than vapor compression system. • COP of compression system is improved by 155% with cascaded absorption system. • Condenser is more sensitive to external fluid temperature as compare to evaporator. - Abstract: In the present study, a thermodynamic model for cascaded vapor compression–absorption system (CVCAS) has been developed which consists of a vapor compression refrigeration system (VCRS) coupled with single effect vapor absorption refrigeration system (VARS). Based on first and second laws, a comparative performance analysis of CVCAS and an independent VCRS has been carried out for a design capacity of 66.67 kW. The results show that the electric power consumption in CVCAS is reduced by 61% and COP of compression section is improved by 155% with respect to the corresponding values pertaining to a conventional VCRS. However there is a trade-off between these parameters and the rational efficiency which is found to decrease to half of that for a VCRS. The effect of various operating parameters, i.e., superheating, subcooling, cooling capacity, inlet temperature and the product of effectiveness and heat capacitance of external fluids are extensively studied on the COP, total irreversibility and rational efficiency of the CVCAS. Besides, the performance of environment friendly refrigerants such as R410A, R407C and R134A is found to be almost at par with that of R22. Hence, all the alternative refrigerants selected herein can serve as potential substitutes for R22. Furthermore, it has been found that reducing the irreversibility rate of the condenser by one unit due to decrease in condenser temperature depicted approximately 3.8 times greater reduction in the total irreversibility rate of the CVCAS, whereas unit reduction in the evaporator’s irreversibility rate due to increase in evaporator temperature reduced

Energy analysis of alternative CO2 refrigeration system configurations for retail food applications in moderate and warm climates

International Nuclear Information System (INIS)

Tsamos, K.M.; Ge, Y.T.; Santosa, IDewa; Tassou, S.A.; Bianchi, G.; Mylona, Z.

2017-01-01

Highlights: • Alternative CO 2 refrigeration technologies are compared for temperate and warm climates. • The CO 2 booster system with parallel compression was found to be the most energy efficient system. • Parallel compression can offer efficiency advantages of 3.6% in moderate and 5.0% in warm climates. • Parallel compression in booster CO 2 systems is economically attractive in warm climates. - Abstract: Refrigeration systems are crucial in retail food stores to ensure appropriate merchandising of food products. This paper compares four different CO 2 refrigeration system configurations in terms of cooling performance, environmental impact, power consumption and annual running costs. The systems studied were the conventional booster refrigeration system with gas bypass (reference system), the all CO 2 cascade system with gas bypass, a booster system with a gas bypass compressor, and integrated cascade all CO 2 system with gas bypass compressor. The weather conditions of London, UK, and Athens, Greece, were used for the modelling of energy consumption and environmental impacts to represent moderate and warm climatic conditions respectively. The control strategies for the refrigeration systems were derived from experimental tests in the laboratory on a conventional booster refrigeration system. The results from the analysis showed that the CO 2 booster system with gas bypass compressor can provide best performance with 5.0% energy savings for the warm climate and 3.65% for the moderate climate, followed by the integrated cascade all CO 2 system with gas bypass compressor, with 3.6% and 2.1% savings over the reference system for the warm and moderate climates respectively.

Profitability considerations for photovoltaics-based solar cooling systems; Wirtschaftlichkeitsbetrachtungen fuer photovoltaik-basierte solare Kuehlsysteme

Energy Technology Data Exchange (ETDEWEB)

Kohlenbach, Paul [Beuth Hochschule fuer Technik, Berlin (Germany). Fachbereich VIII

2016-07-01

In the present article it is studied, under which boundary conditions the application of photovoltaics-based cooling systems is presently economically meaningful. A comparison with a net-drived cold-water set (100 kW{sub r} 5000 full hours/year) as reference system is made. As influence quantity the levelized cost of cooling energy (LCCE) is defined. Following options were studied: - PV system is directly conducted to the cooling facility by means of physical cable connection - PV system is separately fed into the current network and payed back via feeding compensation. Additionally sensitivity analyses of selected parameters on the refrigeration costs were studied.

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...

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

Electron refrigeration in hybrid structures with spin-split superconductors

Science.gov (United States)

Rouco, M.; Heikkilä, T. T.; Bergeret, F. S.

2018-01-01

Electron tunneling between superconductors and normal metals has been used for an efficient refrigeration of electrons in the latter. Such cooling is a nonlinear effect and usually requires a large voltage. Here we study the electron cooling in heterostructures based on superconductors with a spin-splitting field coupled to normal metals via spin-filtering barriers. The cooling power shows a linear term in the applied voltage. This improves the coefficient of performance of electron refrigeration in the normal metal by shifting its optimum cooling to lower voltage, and also allows for cooling the spin-split superconductor by reverting the sign of the voltage. We also show how tunnel coupling spin-split superconductors with regular ones allows for a highly efficient refrigeration of the latter.

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

Measured Performance of Four New 18 kW@4.5 K Helium Refrigerators for the LHC Cryogenic System

CERN Document Server

Gruehagen, Henning

2005-01-01

The cryogenic system for the Large Hadron Collider (LHC) under construction at CERN will include four new 4.5 K-helium refrigerators, to cover part of the cooling needs of the LHC at the 4.5-20 K and 50-75 K levels. Two refrigerators are delivered by Air Liquide, France, and two by Linde Kryotechnik, Switzerland. During the last three years, all four refrigerators have been installed and commissioned at four different points along the LHC. The specified requirements of the refrigerators are presented, with special focus on the capacities at the various temperature levels. The capacities of the refrigerators were measured using a dedicated test cryostat, and the measured performance for all four installations is presented, and compared to the guaranteed performance in the original proposal of the suppliers. Finally, the process design of the two supplies is compared, and their differences and similarities briefly analysed.

Dilution refrigeration with multiple mixing chambers

International Nuclear Information System (INIS)

Coops, G.M.

1981-01-01

A dilution refrigerator is an instrument to reach temperatures in the mK region in a continuous way. The temperature range can be extended and the cooling power can be enlarged by adding an extra mixing chamber. In this way we obtain a double mixing chamber system. In this thesis the theory of the multiple mixing chamber is presented and tested on its validity by comparison with the measurements. Measurements on a dilution refrigerator with a circulation rate up to 2.5 mmol/s are also reported. (Auth.)

Development of a Battery-Free Solar Refrigerator

Science.gov (United States)

Ewert, Michael K.; Bergeron, David J., III

2000-01-01

Recent technology developments and a systems engineering design approach have led to the development of a practical battery-free solar refrigerator as a spin-off of NASA's aerospace refrigeration research. Off-grid refrigeration is a good application of solar photovoltaic (PV) power if thermal storage is incorporated and a direct connection is made between the cooling system and the PV panel. This was accomplished by integrating water as a phase-change material into a well insulated refrigerator cabinet and by developing a microprocessor based control system that allows direct connection of a PV panel to a variable speed compressor. This second innovation also allowed peak power-point tracking from the PV panel and elimination of batteries from the system. First a laboratory unit was developed to prove the concept and then a commercial unit was produced and deployed in a field test. The laboratory unit was used to test many different configurations including thermoelectric, Stirling and vapor compression cooling systems. The final configuration used a vapor compression cooling cycle, vacuum insulation, a passive condenser, an integral evaporator/ thermal storage tank, two 77 watt PV panels and the novel controller mentioned above. The system's only moving part was the variable speed BD35 compressor made by Danfoss. The 365 liter cabinet stayed cold with as little as 274 watt-hours per day average PV power. Battery-free testing was conducted for several months with very good results. The amount of thermal storage, size of compressor and power of PV panels connected can all be adjusted to optimize the design for a given application and climate. In the commercial unit, the high cost of the vacuum insulated refrigerator cabinet and the stainless steel thermal storage tank were addressed in an effort to make the technology commercially viable. This unit started with a 142 liter, mass-produced chest freezer cabinet that had the evaporator integrated into its inner walls

Development of Low Global Warming Potential Refrigerant Solutions for Commercial Refrigeration Systems using a Life Cycle Climate Performance Design Tool

Energy Technology Data Exchange (ETDEWEB)

Abdelaziz, Omar [ORNL; Fricke, Brian A [ORNL; Vineyard, Edward Allan [ORNL

2012-01-01

Commercial refrigeration systems are known to be prone to high leak rates and to consume large amounts of electricity. As such, direct emissions related to refrigerant leakage and indirect emissions resulting from primary energy consumption contribute greatly to their Life Cycle Climate Performance (LCCP). In this paper, an LCCP design tool is used to evaluate the performance of a typical commercial refrigeration system with alternative refrigerants and minor system modifications to provide lower Global Warming Potential (GWP) refrigerant solutions with improved LCCP compared to baseline systems. The LCCP design tool accounts for system performance, ambient temperature, and system load; system performance is evaluated using a validated vapor compression system simulation tool while ambient temperature and system load are devised from a widely used building energy modeling tool (EnergyPlus). The LCCP design tool also accounts for the change in hourly electricity emission rate to yield an accurate prediction of indirect emissions. The analysis shows that conventional commercial refrigeration system life cycle emissions are largely due to direct emissions associated with refrigerant leaks and that system efficiency plays a smaller role in the LCCP. However, as a transition occurs to low GWP refrigerants, the indirect emissions become more relevant. Low GWP refrigerants may not be suitable for drop-in replacements in conventional commercial refrigeration systems; however some mixtures may be introduced as transitional drop-in replacements. These transitional refrigerants have a significantly lower GWP than baseline refrigerants and as such, improved LCCP. The paper concludes with a brief discussion on the tradeoffs between refrigerant GWP, efficiency and capacity.

Operation of a forced two phase cooling system on a large superconducting magnet

International Nuclear Information System (INIS)

Green, M.A.; Burns, W.A.; Eberhard, P.H.; Gibson, G.H.; Pripstein, M.; Ross, R.R.; Smits, R.G.; Taylor, J.D.; Van Slyke, H.

1980-05-01

This paper describes the operation of a forced two phase cooling system on a two meter diameter superconducting solenoid. The magnet is a thin high current density superconducting solenoid which is cooled by forced two phase helium in tubes around the coil. The magnet, which is 2.18 meters in diameter and 3.4 meters long, has a cold mass of 1700 kg. The two phase cooling system contains less than 300 liters of liquid helium, most of which is contained in a control dewar. This paper describes the operating characteristics of the LBL two phase forced cooling system during cooldown and warm up. The paper presents experimental data on operations of the magnet using either a helium pump or the refrigerator compressor to circulate two phase helium through the superconducting coil cooling tubes

Thermodynamic analysis of refrigerant mixtures for possible replacements for CFCs by an algorithm compiling property data

International Nuclear Information System (INIS)

Arcaklioglu, Erol; Cavusoglu, Abdullah; Erisen, Ali

2006-01-01

In this study, we formed an algorithm to find refrigerant mixtures of equal volumetric cooling capacity (VCC) when compared to CFC based refrigerants in vapor compression refrigeration systems. To achieve this aim the point properties of the refrigerants are obtained from REFPROP where appropriate. We used replacement mixture ratios-of varying mass percentages-suggested by various authors along with our newly formed mixture ratios. In other words, we tried to see the effect of changing mass percentages of the suggested (i.e. in the literature) replacement refrigerants on the VCC of the cooling system. Secondly, we used this algorithm to calculate the coefficient of performance (COP) of the same refrigeration system. This mechanism has provided us the ability to compare the COP of the suggested refrigerant mixtures and our newly formed mixture ratios with the conventional CFC based ones. According to our results, for R12 R290/R600a (56/44) mixture, for R22 R32/R125/R134a (32.5/5/62.5) mixture, and for R502 R32/R125/R134a (43/5/52) mixture are appropriate and can be used as replacements

Numerical model for thermoeconomic diagnosis in commercial transcritical/subcritical booster refrigeration systems

DEFF Research Database (Denmark)

Ommen, Torben; Elmegaard, Brian

2012-01-01

cycle supplying refrigerant for evaporators in both chilled and frozen display cases. In the paper, thermoeconomic theory is used to establish the cost of cooling at each individual temperature level based on operating costs.With a high amount of operating systems, faulty operation becomes an economic......, and environmental, interest. A general solution for evaluation of these systems is considered, with the objective to reduce cost and power consumption of malfunctioning equipment in operation. An analysis of the use of thermoeconomic diagnosis methods is required, as these methods may prove applicable...

Energy-efficiency-oriented cascade control for vapor compression refrigeration cycle systems

International Nuclear Information System (INIS)

Yin, Xiaohong; Wang, Xinli; Li, Shaoyuan; Cai, Wenjian

2016-01-01

The vapor compression refrigeration cycle (VCC) system plays an important role and accounts for a large proportion of energy consumption from the heating, ventilating, and air-conditioning (HVAC) system. The traditional control approaches, for example PID control method, however, cannot meet the cooling demands with the satisfactory energy efficiency as well. This paper presents a novel energy-efficiency-oriented cascade control strategy for the VCC systems to improve the energy efficiency and fulfill the cooling requirements of indoor occupants simultaneously. In outer loop, a mathematic model is developed to determine the set point of superheat by a PI controller based on the nonlinear correlation between cooling demands and superheat degree. In inner loop, the pressure difference and superheat degree of evaporator are controlled by a model predictive control (MPC) strategy to track the values which are determined in the outer loop, simultaneously to enhance system efficiency of the VCC systems. Simulation and experiments studies are carried out to show the effectiveness of this proposed cascade control strategy and the results indicate significant tracking performance and energy efficiency improvements on VCC system. Compared to other schemes, the proposed cascade control strategy can improve energy efficiency by up to 5.8%. - Highlights: • Energy-efficiency-oriented cascade control strategy for VCC system is presented. • The correlation between cooling requirements and superheat is analyzed. • A MPC-based controller is developed to maximize system energy efficiency. • Experimental results confirm the effectiveness of the proposed control strategy.

Active cooling for downhole instrumentation: Preliminary analysis and system selection

Energy Technology Data Exchange (ETDEWEB)

Bennett, G.A.

1988-03-01

A feasibility study and a series of preliminary designs and analyses were done to identify candidate processes or cycles for use in active cooling systems for downhole electronic instruments. A matrix of energy types and their possible combinations was developed and the energy conversion process for each pari was identified. The feasibility study revealed conventional as well as unconventional processes and possible refrigerants and identified parameters needing further clarifications. A conceptual design or series od oesigns for each system was formulated and a preliminary analysis of each design was completed. The resulting coefficient of performance for each system was compared with the Carnot COP and all systems were ranked by decreasing COP. The system showing the best combination of COP, exchangeability to other operating conditions, failure mode, and system serviceability is chosen for use as a downhole refrigerator. 85 refs., 48 figs., 33 tabs.

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.

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.

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

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

An Evaluation of the Environmental Impact of Different Commercial Supermarket Refrigeration Systems Using Low Global Warming Potential Refrigerants

Energy Technology Data Exchange (ETDEWEB)

Beshr, Mohamed [University of Maryland, College Park; Aute, Vikrant [University of Maryland, College Park; Abdelaziz, Omar [ORNL; Fricke, Brian A [ORNL; Radermacher, Reinhard [University of Maryland, College Park

2014-01-01

Commercial refrigeration systems consumed 1.21 Quads of primary energy in 2010 and are known to be a major source for refrigerant charge leakage into the environment. Thus, it is important to study the environmental impact of commercial supermarket refrigeration systems and improve their design to minimize any adverse impacts. The system s Life Cycle Climate Performance (LCCP) was presented as a comprehensive metric with the aim of calculating the equivalent mass of carbon dioxide released into the atmosphere throughout its lifetime, from construction to operation and destruction. In this paper, an open source tool for the evaluation of the LCCP of different air-conditioning and refrigeration systems is presented and used to compare the environmental impact of a typical multiplex direct expansion (DX) supermarket refrigeration systems based on three different refrigerants as follows: two hydrofluorocarbon (HFC) refrigerants (R-404A, and R-407F), and a low global warming potential (GWP) refrigerant (N-40). The comparison is performed in 8 US cities representing different climates. The hourly energy consumption of the refrigeration system, required for the calculation of the indirect emissions, is calculated using a widely used building energy modeling tool (EnergyPlus). A sensitivity analysis is performed to determine the impact of system charge and power plant emission factor on the LCCP results. Finally, we performed an uncertainty analysis to determine the uncertainty in total emissions for both R-404A and N-40 operated systems. We found that using low GWP refrigerants causes a considerable drop in the impact of uncertainty in the inputs related to direct emissions on the uncertainty of the total emissions of the system.

Model Based Control of Refrigeration Systems

DEFF Research Database (Denmark)

Larsen, Lars Finn Sloth

for automation of these procedures, that is to incorporate some "intelligence" in the control system, this project was started up. The main emphasis of this work has been on model based methods for system optimizing control in supermarket refrigeration systems. The idea of implementing a system optimizing...... control is to let an optimization procedure take over the task of operating the refrigeration system and thereby replace the role of the operator in the traditional control structure. In the context of refrigeration systems, the idea is to divide the optimizing control structure into two parts: A part...... optimizing the steady state operation "set-point optimizing control" and a part optimizing dynamic behaviour of the system "dynamical optimizing control". A novel approach for set-point optimization will be presented. The general idea is to use a prediction of the steady state, for computation of the cost...

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.

Combination closed-cycle refrigerator/liquid-He4 cryostat for e- damage of bulk samples

International Nuclear Information System (INIS)

Johnson, E.C.

1987-01-01

A closed-cycle refrigerator/cryostat system for use in ultrasonic studies of electron irradiation damaged bulk specimens is described. The closed-cycle refrigerator provides a convenient means for long-term (several days) sample irradiation at low temperatures. A neon filled ''thermal diode'' is employed to permit efficient cooling, via liquid helium, of the sample below the base temperature of the refrigerator

Materials for room temperature magnetic refrigeration

Energy Technology Data Exchange (ETDEWEB)

Rosendahl Hansen, B.

2010-07-15

Magnetic refrigeration is a cooling method, which holds the promise of being cleaner and more efficient than conventional vapor-compression cooling. Much research has been done during the last two decades on various magnetic materials for this purpose and today a number of materials are considered candidates as they fulfill many of the requirements for a magnetic refrigerant. However, no one material stands out and the field is still active with improving the known materials and in the search for a better one. Magnetic cooling is based on the magnetocaloric effect, which causes a magnetic material to change its temperature when a magnetic field is applied or removed. For room temperature cooling, one utilizes that the magnetocaloric effect peaks near magnetic phase transitions and so the materials of interest all have a critical temperature within the range of 250 - 310 K. A magnetic refrigerant should fulfill a number of criteria, among these a large magnetic entropy change, a large adiabatic temperature change, preferably little to no thermal or magnetic hysteresis and the material should have the stability required for long term use. As the temperature range required for room temperature cooling is some 40 - 50 K, the magnetic refrigerant should also be able to cover this temperature span either by exhibiting a very broad peak in magnetocaloric effect or by providing the opportunity for creating a materials series with varying transition temperatures. (Author)

Temperature and pressure control in the discharge of refrigeration systems cooled by shell and tube condensers; Control de presion y temperatura de descarga en sistemas de refrigeracion enfriados por condensadores de casco y tubo

Energy Technology Data Exchange (ETDEWEB)

Fernandez Martinez, R. [Asociacion de Ingenieros Egresados de la Universidad Autonoma Metropolitana, Mexico D. F. (Mexico)

1995-12-31

In the selection of a refrigeration equipment, the evaporator and condenser load conditions must be perfectly known, that is, the amount of heat energy that we have to reject from our space to cool in base to the temperature and mass to refrigerate. This situation carries on to the selection of the adequate compressor. But nevertheless the temperature conditions of the environment play an important roll in the behavior of the entire refrigeration system, altering in many cases the working conditions of each one of the components and therefore the functioning of the refrigeration system. This paper presents a method for controlling the behavior of each one of the components of the refrigeration system that perform in accordance with their design characteristics. [Espanol] En la seleccion de un equipo de refrigeracion, se deben conocer perfectamente las condiciones de carga del evaporador y del condensador, es decir la cantidad de calor que debemos de eliminar de nuestro medio a refrigerar, en base a la temperatura y masa a refrigerar. Esta situacion conlleva a la eleccion del compresor adecuado. Mas sin embargo, las condiciones de temperatura ambiente, juegan un papel importante en el comportamiento de todo el sistema de refrigeracion, alterando en muchos casos las condiciones de trabajo de cada uno de los componentes y por ende el funcionamiento del sistema de refrigeracion. El presente trabajo presenta un metodo para controlar el comportamiento de cada uno de los componentes dentro del sistema de refrigeracion para que trabajen de acuerdo a su diseno.

Temperature and pressure control in the discharge of refrigeration systems cooled by shell and tube condensers; Control de presion y temperatura de descarga en sistemas de refrigeracion enfriados por condensadores de casco y tubo

Energy Technology Data Exchange (ETDEWEB)

Fernandez Martinez, R [Asociacion de Ingenieros Egresados de la Universidad Autonoma Metropolitana, Mexico D. F. (Mexico)

1996-12-31

In the selection of a refrigeration equipment, the evaporator and condenser load conditions must be perfectly known, that is, the amount of heat energy that we have to reject from our space to cool in base to the temperature and mass to refrigerate. This situation carries on to the selection of the adequate compressor. But nevertheless the temperature conditions of the environment play an important roll in the behavior of the entire refrigeration system, altering in many cases the working conditions of each one of the components and therefore the functioning of the refrigeration system. This paper presents a method for controlling the behavior of each one of the components of the refrigeration system that perform in accordance with their design characteristics. [Espanol] En la seleccion de un equipo de refrigeracion, se deben conocer perfectamente las condiciones de carga del evaporador y del condensador, es decir la cantidad de calor que debemos de eliminar de nuestro medio a refrigerar, en base a la temperatura y masa a refrigerar. Esta situacion conlleva a la eleccion del compresor adecuado. Mas sin embargo, las condiciones de temperatura ambiente, juegan un papel importante en el comportamiento de todo el sistema de refrigeracion, alterando en muchos casos las condiciones de trabajo de cada uno de los componentes y por ende el funcionamiento del sistema de refrigeracion. El presente trabajo presenta un metodo para controlar el comportamiento de cada uno de los componentes dentro del sistema de refrigeracion para que trabajen de acuerdo a su diseno.

SolarChill - a solar PV refrigerator without battery

Energy Technology Data Exchange (ETDEWEB)

Pedersen, P.H.; Poulsen, S.; Katic, I. [Danish Technological Inst., Taastrup (Denmark)

2004-07-01

A solar powered refrigerator (SolarChill) has been developed in an international project involving Greenpeace International, GTZ, UNICEF, UNEP, WHO, industrial partners and Danish Technological Institute. The refrigerator is able to operate directly on solar PV panels, without battery or additional electronics, and is therefore suitable for locations where little maintenance and reliable operation is mandatory. The main objective of the SolarChill Project is to help deliver vaccines and refrigeration to the rural poor. To achieve this objective, the SolarChill Project developed - and plans to make freely available a versatile refrigeration technology that is environmentally sound, technologically reliable, and affordable. SolarChill does not use any fluorocarbons in its cooling system or in the insulation. For domestic and small business applications, another type of solar refrigerator is under development. This is an upright type, suitable for cool storage of food and beverages in areas where grid power is non-existent or unstable. The market potential for this type is thus present in industrialised countries as well as in countries under development. The unique feature of SolarChill is that energy is stored in ice instead of in batteries. An ice compartment keeps the cabinet at desired temperatures during the night. The paper describes the product development, possible SolarChill applications and experience with the two types of solar refrigerators, as well as results from the laboratory and field test. (orig.)

Energy-optimised mini-refrigerators; Energieoptimierter Minikuehlschrank. Massnahmen zur Optimierung der Energieeffizienz von Minikuehlschraenken

Energy Technology Data Exchange (ETDEWEB)

Burri, A.

2007-10-15

This illustrated final report for the Swiss Federal Office of Energy (SFOE) takes a look at measures to be taken to optimise the energy-efficiency of small refrigerators. Such devices are typically to be found in hotel rooms and on boats as well as in caravans and motor homes. The majority of these mini-refrigerators use the absorption principle for cooling. Although less efficient than their compressor-driven counterparts, absorption refrigerators satisfy market requirements and customer wishes with regard to noiseless and maintenance-free operation. The report discusses how optimisation of the absorption principle could lead to energy savings in the long term. The operating principles and energy balances of such refrigerators are discussed and a market overview is presented. Energy consumption of the refrigerators, possible savings and energy costs are discussed. The advantages and disadvantages of various cooling systems are examined as are further possibilities for making savings such as the optimisation of sizing, installation methods, airflow factors and operating temperatures.

A small scale remote cooling system for a superconducting cyclotron magnet

Science.gov (United States)

Haug, F.; Berkowitz Zamorra, D.; Michels, M.; Gomez Bosch, R.; Schmid, J.; Striebel, A.; Krueger, A.; Diez, M.; Jakob, M.; Keh, M.; Herberger, W.; Oesterle, D.

2017-02-01

Through a technology transfer program CERN is involved in the R&D of a compact superconducting cyclotron for future clinical radioisotope production, a project led by the Spanish research institute CIEMAT. For the remote cooling of the LTc superconducting magnet operating at 4.5 K, CERN has designed a small scale refrigeration system, the Cryogenic Supply System (CSS). This refrigeration system consists of a commercial two-stage 1.5 W @ 4.2 K GM cryocooler and a separate forced flow circuit. The forced flow circuit extracts the cooling power of the first and the second stage cold tips, respectively. Both units are installed in a common vacuum vessel and, at the final configuration, a low loss transfer line will provide the link to the magnet cryostat for the cooling of the thermal shield with helium at 40 K and the two superconducting coils with two-phase helium at 4.5 K. Currently the CSS is in the testing phase at CERN in stand-alone mode without the magnet and the transfer line. We have added a “validation unit” housed in the vacuum vessel of the CSS representing the thermo-hydraulic part of the cyclotron magnet. It is equipped with electrical heaters which allow the simulation of the thermal loads of the magnet cryostat. A cooling power of 1.4 W at 4.5 K and 25 W at the thermal shield temperature level has been measured. The data produced confirm the design principle of the CSS which could be validated.

Thermodynamic investigation of a booster-assisted ejector refrigeration system

International Nuclear Information System (INIS)

Zhao, Hongxia; Zhang, Ke; Wang, Lei; Han, Jitian

2016-01-01

Highlights: • COP based on thermal input increases with booster outlet pressure. • Both entrainment ratio and area ratio increase with booster outlet pressure. • COP based on work is larger than compressor-based refrigeration system. • An optimum booster outlet pressure obtains maximum COP based on work. • Exergy destruction occurs mainly in ejector, condenser, evaporator and generator. - Abstract: In order to improve performance of ejector refrigeration system, a booster is added before an ejector to enhance secondary flow pressure, which is called a booster assisted refrigeration system. Based on mass, momentum and energy conservation, a 1D model of ejector for optimal performance prediction was presented and validated with experimental data. A detailed study of working characteristics of the booster assisted ejector refrigeration system was carried out and compared against conventional ejector refrigeration system and compressor based refrigeration system, on the basis of first and second laws of thermodynamics. Effects of booster outlet pressure on COP_t_h based on thermal energy and COP_w based on work input, and also on entrainment ratio and area ratio of ejector were studied. The exergy destruction rates were also computed and analyzed for components of the booster-assisted ejector refrigeration system. Ways to reduce exergy destruction were discussed.

Alternative test method to assess the energy performance of frost-free refrigerating appliances

International Nuclear Information System (INIS)

Hermes, Christian J.L.; Melo, Cláudio; Knabben, Fernando T.

2013-01-01

This paper outlines an alternative test method to evaluate the energy consumption of frost-free refrigerators and freezers for residential applications. While the standardized methods require the refrigerating appliance to be kept running according to its onboard control system, which usually drives the refrigerator through an on–off cycling pattern, the proposed approach assesses the refrigerator energy performance in the steady-state regime, being therefore much faster and more reliable. In this procedure, the cooling capacity is matched to the cooling loads by PID-controlled electrical heaters installed within the refrigerated compartments, so that the compartment temperatures are kept at the desired standardized levels. Comparisons between the experimental results obtained using the steady-state energy test and the standardized procedures showed that the former follows closely the trends observed for the latter. - Highlights: ► An alternative test method to assess the energy consumption of refrigerators is proposed. ► PID-controlled electrical heaters were installed within the compartments. ► Steady-state and ISO energy tests were performed and compared. ► Both proposed and standardized test procedures showed similar trends.

Analysis of an electricity–cooling cogeneration system based on RC–ARS combined cycle aboard ship

International Nuclear Information System (INIS)

Liang, Youcai; Shu, Gequn; Tian, Hua; Liang, Xingyu; Wei, Haiqiao; Liu, Lina

2013-01-01

Highlights: • A novel electricity–cooling cogeneration system was used to recover waste heat aboard ships. • Performance of such RC–ARS system was investigated theoretically. • Optimal exergy output can be obtained when the vaporization pressure of RC is 300 kPa. • The exergy efficiency of cogeneration system is 5–12% higher than that of basic Rankine cycle only. - Abstract: In this paper, an electricity–cooling cogeneration system based on Rankine–absorption refrigeration combined cycle is proposed to recover the waste heat of the engine coolant and exhaust gas to generate electricity and cooling onboard ships. Water is selected as the working fluid of the Rankine cycle (RC), and a binary solution of ammonia–water is used as the working fluid of the absorption refrigeration cycle. The working fluid of RC is preheated by the engine coolant and then evaporated and superheated by the exhaust gas. The absorption cycle is powered by the heat of steam at the turbine outlet. Electricity output, cooling capacity, total exergy output, primary energy ratio (PER) and exergy efficiency are chosen as the objective functions. Results show that the amount of additional cooling output is up to 18 MW. Exergy output reaches the maximum 4.65 MW at the vaporization pressure of 300 kPa. The study reveals that the electricity–cooling cogeneration system has improved the exergy efficiency significantly: 5–12% increase compared with the basic Rankine cycle only. Primary energy ratio (PER) decreases as the vaporization pressure increases, varying from 0.47 to 0.40

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.

A rotary permanent magnet magnetic refrigerator based on AMR cycle

International Nuclear Information System (INIS)

Aprea, C.; Cardillo, G.; Greco, A.; Maiorino, A.; Masselli, C.

2016-01-01

Magnetic refrigeration is an emerging, environment-friendly technology based on a magnetic solid that acts as a refrigerant by magneto-caloric effect (MCE). The reference cycle for magnetic refrigeration is AMR (Active Magnetic Regenerative refrigeration). In order to demonstrate the potential of magnetic refrigeration to provide useful cooling in the near room temperature range, a novel Rotary Permanent Magnet Magnetic Refrigerator (RPMMR) is described in this paper. Gadolinium has been selected as magnetic refrigerant and demineralized water has been employed as regenerating fluid. The total mass of gadolinium (1.20 kg), shaped as packed bed spheres, is housed in 8 regenerators. A magnetic system, based on a double U configuration of permanent magnets, provides a magnetic flux density of 1.25 T with an air gap of 43 mm. A rotary vane pump forces the regenerating fluid through the regenerators. The operational principle of the magnetic refrigerator and initial experimental results are reported and analyzed.

RESEARCH OF REFRIGERATION SYSTEMS FAILURES IN POLISH FISHING VESSELS

Directory of Open Access Journals (Sweden)

Waldemar KOSTRZEWA

2013-07-01

Full Text Available Temperature is a basic climatic parameter deciding about the quality change of fishing products. Time, after which qualitative changes of caught fish don’t exceed established, acceptable range, is above all the temperature function. Temperature reduction by refrigeration system of the cargo hold is a basic technical method, which allows extend transport time. Failures of refrigeration systems in fishing vessels have a negative impact on the environment in relation to harmful refrigerants emission. The paper presents the statistical analysis of failures occurred in the refrigeration systems of Polish fishing vessels in 2007‐2011 years. Analysis results described in the paper can be a base to draw up guidelines, both for designers as well as operators of the marine refrigeration systems.

Fluid Induced Vibration Analysis of a Cooling Water Pipeline for the HANARO CNS

International Nuclear Information System (INIS)

Kim, Bong Soo; Lee, Young Sub; Kim, Ik Soo; Kim, Young Ki

2007-01-01

CNS is the initial of Cold Neutron Source and the CNS facility system consists of hydrogen, a vacuum, a gas blanketing, a helium refrigeration and a cooling water supply system. Out of these subsystems, the helium refrigeration system has the function of removal of heat from a thermal neutron under reactor operation. Therefore, HRS (helium refrigeration system) must be under normal operation for the production of cold neutron. HRS is mainly made up of a helium compressor and a coldbox. This equipment is in need of cooling water to get rid of heat generation under stable operation and a cooling water system is essential to maintain the normal operation of a helium compressor and a coldbox. The main problem for the cooling water system is the vibration issue in the middle of operation due to a water flow in a pipeline. In order to suppress the vibration problem for a pipeline, the characteristics of a pipeline and fluid flow must be analyzed in detail. In this paper, fluid induced vibration of a cooling water pipe is analyzed numerically and the stability of the cooling water pipeline is investigated by using pipe dynamic theory

Mobile refrigeration system for precool and warm up of superconducting magnets

Science.gov (United States)

Gandla, S. K.; Longsworth, R. C.

2017-12-01

Conservation of helium has become more important in recent years due to global shortages in supply. Magnetic resonance imaging (MRI) superconducting magnets use approximately 20% of the world’s helium reserves in liquid form to cool down and maintain operating temperatures at 4 K. This paper describes a mobile cryogenic refrigeration system, which has been developed by Sumitomo (SHI) Cryogenics of America, Inc. to conserve helium by shipping MRI magnets warm and cooling them down or servicing them on site at a medical facility. The system can cool a typical magnet from room temperature to below 40K in less than a week. The system consists of four single stage Displex®-type Gifford-McMahon (GM) expanders in a cryostat with heat exchangers integrated on the cold ends that cool the helium gas, which is circulated in a closed-loop system through the magnet by a cryogenic fan. The system is configured with heaters on the heat exchangers to effectively warm up a magnet. The system includes a scroll vacuum pump, which is used to evacuate the helium circuit with or without the magnet and turbo pump to evacuate the cryostat. Vacuum-jacketed transfer lines connect the cryostat to the magnet. The system is designed with its own controller for continuous operation of precool, warm up and evacuation processes with automatic and manual controls. The cryostat, pumps and gas controls are mounted on a dewar cart. One compressor and the system controller are mounted on a compressor and control cart, and the other three compressors are mounted on separate carts.

Thermodynamic analysis of a new combined cooling and power system using ammonia–water mixture

International Nuclear Information System (INIS)

Wang, Jiangfeng; Wang, Jianyong; Zhao, Pan; Dai, Yiping

2016-01-01

Highlights: • A new combined cooling and power system is proposed. • Exergy destruction analysis is used to identify irreversibility of components in system. • Thermodynamic parameter analysis is performed for system. - Abstract: In order to achieve both power and cooling supply for users, a new combined cooling and power system using ammonia–water mixture is proposed to utilizing low grade heat sources, such as industrial waste heat, solar energy and geothermal energy. The proposed system combines a Kalina cycle and an ammonia–water absorption refrigeration cycle, in which the ammonia–water turbine exhaust is delivered to a separator to extract purer ammonia vapor. The purer ammonia vapor enters an evaporator to generate refrigeration output after being condensed and throttled. Mathematical models are established to simulate the combined system under steady-state conditions. Exergy destruction analysis is conducted to display the exergy destruction distribution in the system qualitatively and the results show that the major exergy destruction occurs in the heat exchangers. Finally a thermodynamic sensitivity analysis is performed and reveals that with an increase in the pressure of separator I or the ammonia mass fraction of basic solution, thermal efficiency and exergy efficiency of the system increase, whereas with an increase in the temperature of separator I, the ammonia–water turbine back pressure or the condenser II pressure, thermal efficiency and exergy efficiency of the system drop.

Exergeoconomic analysis and optimization of a novel cogeneration system producing power and refrigeration

International Nuclear Information System (INIS)

Akbari Kordlar, M.; Mahmoudi, S.M.S.

2017-01-01

Highlights: • A novel combined cooling and power cogeneration system is proposed. • Thermodynamic and exergoeconomic analyses are performed. • Optimizations are performed considering thermodynamics and economics. • An increase in turbine inlet pressure is in favor of the system performance. • Five parameters influence the total product unit cost. - Abstract: A novel combined cooling and power cogeneration system driven by geothermal hot water is proposed. The system, which is a combination of an organic Rankine cycle and an absorption refrigeration cycle, is analyzed and optimized from the viewpoints of thermodynamics and economics. The working fluid in organic Rankine cycle is ammonia and in the refrigeration cycle is an ammonia-water solution. Parametric studies are performed to identify decision parameters prior to optimization. In optimizing the system performance three design cases i.e. designs for maximum first law efficiency (case1), maximum second law efficiency (case2) and minimum total product unit cost (case3) are considered. The results show that the total products unit cost in case3 is around 20.4% and 24.3% lower than the corresponding value in case1 and 2, respectively. The lower product unit cost in case3 is accompanied with an expense of 10.21% and 4.5% reduction in the first and second law efficiencies, compared to case1 and 2, respectively. The results also indicate that concerning the costs associated with capital and exergy destruction costs of components, the priority of components for modifications are the turbine, condenser and absorber. The last component in this order are the two pumps in the system.

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

Zero boil-off methods for large-scale liquid hydrogen tanks using integrated refrigeration and storage

Science.gov (United States)

Notardonato, W. U.; Swanger, A. M.; E Fesmire, J.; Jumper, K. M.; Johnson, W. L.; Tomsik, T. M.

2017-12-01

NASA has completed a series of tests at the Kennedy Space Center to demonstrate the capability of using integrated refrigeration and storage (IRAS) to remove energy from a liquid hydrogen (LH2) tank and control the state of the propellant. A primary test objective was the keeping and storing of the liquid in a zero boil-off state, so that the total heat leak entering the tank is removed by a cryogenic refrigerator with an internal heat exchanger. The LH2 is therefore stored and kept with zero losses for an indefinite period of time. The LH2 tank is a horizontal cylindrical geometry with a vacuum-jacketed, multilayer insulation system and a capacity of 125,000 liters. The closed-loop helium refrigeration system was a Linde LR1620 capable of 390W cooling at 20K (without any liquid nitrogen pre-cooling). Three different control methods were used to obtain zero boil-off: temperature control of the helium refrigerant, refrigerator control using the tank pressure sensor, and duty cycling (on/off) of the refrigerator as needed. Summarized are the IRAS design approach, zero boil-off control methods, and results of the series of zero boil-off tests.

ATLAS' major cooling project

CERN Multimedia

2005-01-01

In 2005, a considerable effort has been put into commissioning the various units of ATLAS' complex cryogenic system. This is in preparation for the imminent cooling of some of the largest components of the detector in their final underground configuration. The liquid helium and nitrogen ATLAS refrigerators in USA 15. Cryogenics plays a vital role in operating massive detectors such as ATLAS. In many ways the liquefied argon, nitrogen and helium are the life-blood of the detector. ATLAS could not function without cryogens that will be constantly pumped via proximity systems to the superconducting magnets and subdetectors. In recent weeks compressors at the surface and underground refrigerators, dewars, pumps, linkages and all manner of other components related to the cryogenic system have been tested and commissioned. Fifty metres underground The helium and nitrogen refrigerators, installed inside the service cavern, are an important part of the ATLAS cryogenic system. Two independent helium refrigerators ...

Macroscopic Refrigeration Using Superconducting Tunnel Junctions

Science.gov (United States)

Lowell, Peter; O'Neil, Galen; Underwood, Jason; Zhang, Xiaohang; Ullom, Joel

2014-03-01

Sub-kelvin temperatures are often a prerequisite for modern scientific experiments, such as quantum information processing, astrophysical missions looking for dark energy signatures and tabletop time resolved x-ray spectroscopy. Existing methods of reaching these temperatures, such as dilution refrigerators, are bulky and costly. In order to increase the accessibility of sub-Kelvin temperatures, we have developed a new method of refrigeration using normal-metal/insulator/superconductor (NIS) tunnel junctions. NIS junctions cool the electrons in the normal metal since the hottest electrons selectively tunnel from the normal metal into the superconductor. By extending the normal metal onto a thermally isolated membrane, the cold electrons can cool the phonons through the electron-phonon coupling. When these junctions are combined with a pumped 3He system, they provide a potentially inexpensive method of reaching these temperatures. Using only three devices, each with a junction area of approximately 3,500 μm2, we have cooled a 2 cm3 Cu plate from 290 mK to 256 mK. We will present these experimental results along with recent modeling predictions that strongly suggest that further refinements will allow cooling from 300 mK to 120 mK. This work is supported by the NASA APRA program.

Improving the energy efficiency of industrial refrigeration systems

International Nuclear Information System (INIS)

Oh, Jin-Sik; Binns, Michael; Park, Sangmin; Kim, Jin-Kuk

2016-01-01

Various retrofit design options are available for improving the energy efficiency and economics of industrial refrigeration systems. This study considers a novel retrofit option using a mixed refrigerant (MR) in refrigeration cycles designed for use with a pure refrigerant (PR). In this way energy savings can be realized by switching refrigerants without requiring extensive and expensive reconfiguration of equipment. Hence, the aim here is to test the common thinking that equipment should always be extensively reconfigured when switching from pure to mixed refrigerants. To determine the most energy-efficient operating conditions for each refrigeration design an optimization framework is utilized linking a process simulator with an external optimization method. A case study is presented to demonstrate how the proposed process modeling and optimization framework can be applied and to illustrate the economic benefits of using the retrofit design options considered here. For the case considered in this paper, savings of shaft power required for the refrigeration cycle can be achieved from 16.3% to 27.2% when the pure refrigerant is replaced with mixed refrigerants and operating conditions are re-optimized. - Highlights: • Design methods for the design of refrigeration cycles in retrofit cases. • Consideration of mixed refrigerants to the existing multi-level pure-refrigerant cycles. • Optimization of refrigeration cycles with integrated use of a process simulator with an optimizer.

Testing and further development of a solar absorption cooling plant

Science.gov (United States)

Amannsberger, K.; Heckel, H.; Kreutmair, J.; Weber, K. H.

1984-12-01

Ammonia water absorption cooling units using the process heat of line-focusing solar collectors were developed and tested. Reduction of the evaporation temperature to minus 10 C; development of an air-cooled rectifying device for the refrigerant vapor; dry cooling of absorber and condenser by natural draft; refrigerating capacities of 14 to 10 kW which correspond to air temperatures of 25 to 40 C and 24 kW power consumption to heat the machine; auxiliary power requirement 450 W; full compatibility with changing heat input and air temperature, adaptation by automatic stabilization effects; and power optimization under changing boundary conditions by a simple regulating procedure independent of auxiliary power are achieved. The dynamic behavior of the directly linked collector-refrigeration machine system was determined. Operating conditions, market, and economic viability of solar cooling in third-world countries are described. Ice production procedures using absorption cooling units are demonstrated.

Adiabatic cooling processes in frustrated magnetic systems with pyrochlore structure

Science.gov (United States)

Jurčišinová, E.; Jurčišin, M.

2017-11-01

We investigate in detail the process of adiabatic cooling in the framework of the exactly solvable antiferromagnetic spin-1/2 Ising model in the presence of the external magnetic field on an approximate lattice with pyrochlore structure. The behavior of the entropy of the model is studied and exact values of the residual entropies of all ground states are found. The temperature variation of the system under adiabatic (de)magnetization is investigated and the central role of the macroscopically degenerated ground states in cooling processes is explicitly demonstrated. It is shown that the model parameter space of the studied geometrically frustrated system is divided into five disjunct regions with qualitatively different processes of the adiabatic cooling. The effectiveness of the adiabatic (de)magnetization cooling in the studied model is compared to the corresponding processes in paramagnetic salts. It is shown that the processes of the adiabatic cooling in the antiferromagnetic frustrated systems are much more effective especially in nonzero external magnetic fields. It means that the frustrated magnetic materials with pyrochlore structure can be considered as very promising refrigerants mainly in the situations with nonzero final values of the magnetic field.

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.

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.

Power Consumption in Refrigeration Systems - Modeling for Optimization

DEFF Research Database (Denmark)

Hovgaard, Tobias Gybel; Larsen, Lars F. S.; Skovrup, Morten Juel

2011-01-01

Refrigeration systems consume a substantial amount of energy. Taking for instance supermarket refrigeration systems as an example they can account for up to 50−80% of the total energy consumption in the supermarket. Due to the thermal capacity made up by the refrigerated goods in the system...... there is a possibility for optimizing the power consumption by utilizing load shifting strategies. This paper describes the dynamics and the modeling of a vapor compression refrigeration system needed for sufficiently realistic estimation of the power consumption and its minimization. This leads to a non-convex function...... with possibly multiple extrema. Such a function can not directly be optimized by standard methods and a qualitative analysis of the system’s constraints is presented. The description of power consumption contains nonlinear terms which are approximated by linear functions in the control variables and the error...

5-year operation experience with the 1.8 K refrigeration units of the LHC cryogenic system

CERN Document Server

Ferlin, G; Claudet, S; Pezzetti, M

2015-01-01

Since 2009, the Large Hadron Collider (LHC) is in operation at CERN. The LHC superconducting magnets distributed over eight sectors of 3.3-km long are cooled at 1.9 K in pressurized superfluid helium. The nominal operating temperature of 1.9 K is produced by eight 1.8-K refrigeration units based on centrifugal cold compressors (3 or 4 stages depending to the vendor) combined with warm volumetric screw compressors with sub-atmospheric suction. After about 5 years of continuous operation, we will present the results concerning the availability for the final user of these refrigeration units and the impact of the design choice on the recovery time after a system trip. We will also present the individual results for each rotating machinery in terms of failure origin and of Mean Time between Failure (MTBF), as well as the consolidations and upgrades applied to these refrigeration units.

5-year operation experience with the 1.8 K refrigeration units of the LHC cryogenic system

Science.gov (United States)

Ferlin, G.; Tavian, L.; Claudet, S.; Pezzetti, M.

2015-12-01

Since 2009, the Large Hadron Collider (LHC) is in operation at CERN. The LHC superconducting magnets distributed over eight sectors of 3.3-km long are cooled at 1.9 K in pressurized superfluid helium. The nominal operating temperature of 1.9 K is produced by eight 1.8-K refrigeration units based on centrifugal cold compressors (3 or 4 stages depending to the vendor) combined with warm volumetric screw compressors with sub-atmospheric suction. After about 5 years of continuous operation, we will present the results concerning the availability for the final user of these refrigeration units and the impact of the design choice on the recovery time after a system trip. We will also present the individual results for each rotating machinery in terms of failure origin and of Mean Time between Failure (MTBF), as well as the consolidations and upgrades applied to these refrigeration units.

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

Experimental Investigation on an Absorption Refrigerator Driven by Solar Cells

Directory of Open Access Journals (Sweden)

Zi-Jie Chien

2013-01-01

Full Text Available This experiment is to study an absorption refrigerator driven by solar cells. Hand-held or carried in vehicle can be powered by solar energy in places without power. In the evenings or rainy days, it is powered by storage battery, and it can be directly powered by alternating current (AC power supply if available, and the storage battery can be charged full as a backup supply. The proposed system was tested by the alternation of solar irradiance 550 to 700 W/m2 as solar energy and 500ml ambient temperature water as cooling load. After 160 minutes, the proposal refrigerator can maintain the temperature at 5–8°C, and the coefficient of performance (COP of NH3-H2O absorption refrigeration system is about 0.25. Therefore, this system can be expected to be used in remote areas for refrigeration of food and beverages in outdoor activities in remote and desert areas or long-distance road transportation of food or low temperature refrigeration of vaccine to avoid the deterioration of the food or the vaccines.

Energy and exergy analyses of a bi-evaporator compression/ejection refrigeration cycle

International Nuclear Information System (INIS)

Geng, Lihong; Liu, Huadong; Wei, Xinli; Hou, Zhonglan; Wang, Zhenzhen

2016-01-01

Highlights: • A bi-evaporator compression/ejection refrigeration cycle was studied experimentally. • Experiments were operated at the same external conditions and cooling capacities. • COP improvement was 16.94–30.59% higher than that of the conventional system. • The exergy efficiency of the R134a cycle was improved by 7.57–28.29%. - Abstract: Aiming to reduce the throttling loss in the vapor compression refrigeration cycle, a bi-evaporator compression/ejection refrigeration cycle (BCERC) using an ejector as the expansion device was experimentally investigated with R134a refrigerant. The effects of the compressor frequency and the operating conditions on the coefficient of performance (COP) and the amount of exergy destruction of each component were studied. The results were compared with that of the conventional vapor compression refrigeration cycle under the same external operating conditions and cooling capacities. Results showed that the refrigeration cycle with an ejector as the expansion device exhibited lower irreversibility for each component and total system in comparison with the conventional vapor compression refrigeration cycle. The COP and the exergy efficiency of the BCERC were higher than that of the conventional system. The COP and exergy efficiency improvements became more significant as the condenser water temperature increased, the evaporator water temperature decreased and the compressor frequency increased. In the BCERC with a constant frequency compressor, the COP and the exergy efficiency could be improved by 16.94–30.59%, 7.57–28.29%, respectively. The COP and the exergy efficiency of the BCERC with a variable frequency compressor could increase by around 32.64% and 23.32%, respectively.

Water cooling system for sintering furnaces of nuclear fuel pellets; Sistema de enfriamiento con agua para hornos de sinterizado de pastillas de combustible nuclear

Energy Technology Data Exchange (ETDEWEB)

NONE

1996-11-01

This work has as a main objective to develop a continuous cooling water system, which is necessary for the cooling of the sintering furnaces. This system is used to protect them as well as for reducing the water consumption, ejecting the heat generated into this furnaces and scattering it into the atmosphere in a fast and continuous way. The problem was defined and the reference parameters established, making the adequate research. The materials were selected as well as the length of the pipeline which will carry the secondary refrigerant fluid (water). Three possible solutions were tried,and evaluated, and from these, the thermal and economically most efficient option was selected. The layout of the solution was established and the theoretical construction of a cooling system for liquids using dichlorofluoromethane (R-22), as a refrigerant and a air cooled condenser, was accomplished. (Author).

Cryogenic refrigeration. (Latest citations from the Aerospace database). Published Search

International Nuclear Information System (INIS)

1993-09-01

The bibliography contains citations concerning cryogenic refrigeration or cryocooling. Design, development, testing, and evaluation of cryogenic cooling systems are discussed. Design applications in spacecraft, magnet cooling, superconductors, liquid fuel storage, radioastronomy, and medicine are presented. Material properties at cryogenic temperatures and cryogenic rocket propellants are considered in separate bibliographies. (Contains 250 citations and includes a subject term index and title list.)

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...

PERFORMANCE EVALUATION OF CEILING RADIANT COOLING SYSTEM IN COMPOSITE CLIMATE

Energy Technology Data Exchange (ETDEWEB)

Sharma, Anuj [Malaviya National Institute of Technology (MNIT), Jaipur, India; Mathur, Jyotirmay [Malaviya National Institute of Technology (MNIT), Jaipur, India; Bhandari, Mahabir S [ORNL

2015-01-01

Radiant cooling systems are proving to be an energy efficient solution due to higher thermal capacity of cooling fluid especially for the buildings that require individual zone controls and where the latent loads are moderate. The Conventional air conditioners work at very low temperature i.e.5-8 c (refrigerant evaporator inlet) while the radiant cooling systems, also referred as high temperature cooling system, work at high temperatures i.e. 14-18 c. The radiant cooling systems can maintain lower MRT (Mean Radiant Temperature) as ceiling panels maintain uniform temperature gradient inside room and provide higher human comfort. The radiant cooling systems are relatively new systems and their operation and energy savings potential are not quantified for a large number of buildings and operational parameters. Moreover, there are only limited numbers of whole building simulation studies have been carried out for these systems to have a full confidence in the capability of modelling tools to simulate these systems and predict the impact of various operating parameters. Theoretically, savings achieve due to higher temperature set point of chilled water, which reduces chiller-running time. However, conventional air conditioner runs continuously to maintain requisite temperature. In this paper, experimental study for performance evaluation of radiant cooling system carried out on system installed at Malaviya National Institute of Technology Jaipur. This paper quantifies the energy savings opportunities and effective temperature by radiant cooling system at different chilled water flow rates and temperature range. The data collected/ analysed through experimental study will used for calibration and validation of system model of building prepared in building performance simulation software. This validated model used for exploring optimized combinations of key parameters for composite climate. These optimized combinations will used in formulation of radiant cooling system

Design and performance characteristics of solar adsorption refrigeration system using parabolic trough collector: Experimental and statistical optimization technique

International Nuclear Information System (INIS)

Abu-Hamdeh, Nidal H.; Alnefaie, Khaled A.; Almitani, Khalid H.

2013-01-01

Highlights: • The successes of using olive waste/methanol as an adsorbent/adsorbate pair. • The experimental gross cycle coefficient of performance obtained was COP a = 0.75. • Optimization showed expanding adsorbent mass to a certain range increases the COP. • The statistical optimization led to optimum tank volume between 0.2 and 0.3 m 3 . • Increasing the collector area to a certain range increased the COP. - Abstract: The current work demonstrates a developed model of a solar adsorption refrigeration system with specific requirements and specifications. The recent scheme can be employed as a refrigerator and cooler unit suitable for remote areas. The unit runs through a parabolic trough solar collector (PTC) and uses olive waste as adsorbent with methanol as adsorbate. Cooling production, COP (coefficient of performance, and COP a (cycle gross coefficient of performance) were used to assess the system performance. The system’s design optimum parameters in this study were arrived to through statistical and experimental methods. The lowest temperature attained in the refrigerated space was 4 °C and the equivalent ambient temperature was 27 °C. The temperature started to decrease steadily at 20:30 – when the actual cooling started – until it reached 4 °C at 01:30 in the next day when it rose again. The highest COP a obtained was 0.75

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.

Cooling process in separation devices of krypton gas

Energy Technology Data Exchange (ETDEWEB)

Kimura, S; Sugimoto, K

1975-06-11

To prevent entry of impurities into purified gases and to detect leaks of heat exchanger in a separation and recovering device of krypton gas by means of liquefaction and distillation, an intermediate refrigerant having the same or slightly higher boiling point than that of gas to be cooled is used between the gas to be cooled (process gas) and refrigerant (nitrogen), and the pressure of the gas to be cooled is controlled to have a pressure higher than the intermediate refrigerant to cool the gas to be cooled.

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.

Slurry Ice as a Cooling System on 30 GT Fishing Vessel

Directory of Open Access Journals (Sweden)

Alam Baheramsyah

2017-06-01

Full Text Available Indonesia is the largest archipelago country in the world that has a sea area that is very spacious. Indonesian sea area is 5.8 million square kilometers and a coastline of 95 181 km has huge potential in the fisheries sector. In line with the need to further improve on the quality of the fish catch. One way to preserve fish is to use a slurry of ice. Slurry ice proved more effective preserving fishery products instead of using ice cubes. Ice slurry cooling system was designed and applied to the fishing vessel 30 GT. The cooling system uses a simple vapor compression system consists of five major components consisting of evaporator, condenser, compressor, and two pumps.In designing this system determined the type of refrigerant used in advance which type of refrigerant R-507a. Then do the design or selection of its main components. The design is only done on the evaporator. As for the other major components such as condensers, compressors, and pumps election in accordance with the specification of the power needed. After that dialakukan depiction of each system component. Then subsequently designing the laying of ice slurry cooling system components on a fishing vessel 30 GT.            Through calculations using simple thermodynamic equations obtained cooling load on this system amounted to 32.06 kW. Condenser with a power of 40 kW. Compressor with power 12 kW. Pump with capacity 10 m3 / h. With memepertimbangkan space left on the ship in the ice slurry system design on the main deck of the ship to the efficient use of space on board. The power requirements of the generator vessel increases due to the addition of ice slurry system components therefore do replacement generator into the generator with a power of 100 kW and penambahn fuel tank to 6,000 L.

A new type of liquid-3He target system using small mechanical refrigerators

International Nuclear Information System (INIS)

Kato, S.; Kobayashi, K.; Maruyama, K.; Okuno, H.; Konno, O.; Suda, T.; Maki, T.; Asami, H.; Koizumi, T.

1991-04-01

A new type of liquid- 3 He target has been developed for photoabsorption experiments at intermediate energies. Using the cooling power of liquid 4 He at reduced vapour pressure, 3 He gas is liquefied into a cylindrical target cell of 180 ml and is maintained at 2.0 K during the experiment. Evaporated 4 He gas is evacuated by a rotary pump and returned into the 4 He bath in the cryostat, where two small mechanical refrigerators with cooling capacities of 3 W at 4.3 K and 10 W at 20 K are operated for the purpose of 4 He recondensation. A maintenance-free operation of more than 1,000 hours has become possible by adopting the 4 He circulation system. (author)

Improvement in performance of a direct solar-thermally driven diffusion-absorption refrigerator; Leistungssteigerung einer direkt solarthermisch angetriebenen Diffusions-Absorptionskaeltemaschine

Energy Technology Data Exchange (ETDEWEB)

Schmid, Fabian; Bierling, Bernd; Spindler, Klaus [Stuttgart Univ. (Germany). Inst. fuer Thermodynamik und Waermetechnik (ITW)

2012-07-01

The diffusion-absorption refrigeration process offers the possibility of a wear-free refrigeration system without electricity and noise. At the Institute for Thermodynamics and Thermal Engineering (Stuttgart, Federal Republic of Germany), a decentralized solar refrigeration system is developed based on this process. The expeller and the thermosiphon pump of this process are integrated in the collector, and thus are heated directly. The diffusion-absorption refrigeration process also can be used for domestic water heating by means of a second cycle in the collector. A cooling capacity of 400 W is to be achieved for each solar collector (2.5 m{sup 2}). Several refrigeration systems can be modular interconnected for higher cooling capacities. As part of the DKV Conference 2011, the construction of the plant, the first measurement data and results were presented. Since then, both the cooling capacity and the coefficient of performance of the diffusion-absorption refrigeration system could be increased significantly. For this, solvent heat exchanger, evaporator, absorber and gas heat exchanger have been optimized in terms of system efficiency. In addition, a stable system operation could be achieved by means of a bypass line. About this line, an exaggerated refrigerant already is removed in the solvent heat exchanger. In addition, a condensate pre-cooler was integrated in order to increase the efficiency. For a detailed investigation of the auxiliary gas cycle facilities, the volume flow and the concentration of the auxiliary gas circuit were examined under utilization of an ultrasonic sensor. In order to evaluate the influence factors by means of a parametric study, the mass transfer in the auxiliary gas circuit was simulated using the two-fluid model. The results of these studies, the current system configuration and the current results are presented in the contribution under consideration.

The maintenance record of the KSTAR helium refrigeration system

Energy Technology Data Exchange (ETDEWEB)

Moon, K. M.; Joo, J. J.; Kim, N. W. [National Fusion Research Institute, Daejeon (Korea, Republic of); and others

2013-12-15

Korea Superconducting Tokamak Advanced Research (KSTAR) has a helium refrigeration system (HRS) with the cooling capacity of 9 kW at 4.5 K. Main cold components are composed of 300 tons of superconducting (SC) magnets, main cryostat thermal shields, and SC current feeder system. The HRS comprises six gas storage tanks, a liquid nitrogen tank, the room temperature compression sector, the cold box (C/B), the 1st stage helium distribution box (DB no.1), the PLC base local control system interconnected to central control tower and so on. Between HRS and cold components, there is another distribution box (DB#2) nearby the KSTAR device. The entire KSTAR device was constructed in 2007 and has been operated since 2008. This paper will present the maintenance result of the KSTAR HRS during the campaign and discuss the operation record and maintenance history of the KSTAR HRS.

Thermodynamic, Environmental and Economic Analyses of Solar Ejector Refrigeration System Application for Cold Storage

OpenAIRE

İbrahim ÜÇGÜL

2009-01-01

The refrigeration processes have been widely applied for especially in cold storages. In these plants, the systems working with compressed vapour cooling cycles have been used as a classical method. In general, electrical energy is used for compressing in these processes. Although, mainly the electricity itself has no pollution effect on the environment, the fossil fuels that are widely used to produce electricity in the most of the world, affect the nature terribly. In short, these refrigera...

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

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.

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%

The integration of cryogenic cooling systems with superconducting electronic systems

International Nuclear Information System (INIS)

Green, Michael A.

2003-01-01

The need for cryogenic cooling has been critical issue that has kept superconducting electronic devices from reaching the market place. Even though the performance of the superconducting circuit is superior to silicon electronics, the requirement for cryogenic cooling has put the superconducting devices at a disadvantage. This report will talk about the various methods for refrigerating superconducting devices. Cryocooler types will be compared for vibration, efficiency, and cost. Some solutions to specific problems of integrating cryocoolers to superconducting devices are presented.

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.

Synchronous temperature rate control and apparatus for refrigeration with reduced energy consumption

Science.gov (United States)

Gomes, Alberto Regio; Keres, Stephen L.; Kuehl, Steven J.; Litch, Andrew D.; Richmond, Peter J.; Wu, Guolian

2015-09-22

A refrigerator appliance configuration, and associated methods of operation, for an appliance with a controller, a condenser, at least one evaporator, a compressor, and two refrigeration compartments. The configuration may be equipped with a variable-speed or variable-capacity compressor, variable speed evaporator or compartment fans, a damper, and/or a dual-temperature evaporator with a valve system to control flow of refrigerant through one or more pressure reduction devices. The controller, by operation of the compressor, fans, damper and/or valve system, depending on the appliance configuration, synchronizes alternating cycles of cooling each compartment to a temperature approximately equal to the compartment set point temperature.

Experimental evaluation of R448A as R404A lower-GWP alternative in refrigeration systems

International Nuclear Information System (INIS)

Mota-Babiloni, Adrián; Navarro-Esbrí, Joaquín; Peris, Bernardo; Molés, Francisco; Verdú, Gumersindo

2015-01-01

Highlights: • R448A (GWP = 1273) is an A1 refrigerant proposed in DX supermarket refrigeration systems. • Performance of R448A and R404A is evaluated under different conditions. • R448A presents lower cooling capacity but higher COP than R404A. • The R448A maximum discharge temperature is always below 380 K. • R448A is more interesting at high condensing (ambient) temperatures. - Abstract: Due to the adoption of EU Regulation No 517/2014, R404A is going to be banned in Europe in most of refrigeration applications, in which is typically used, due to its very high GWP value, 3943. In this paper an experimental comparison between R404A and R448A, a non-flammable alternative with GWP of 1390, is presented. The experimental tests are intended to simulate typical freezing and conservation temperatures and different condensing conditions. Despite cooling capacity of R448A is slightly below that of R404A, R448A energy consumption is even smaller; and R448A COP is higher than that obtained using R404A. Hence, it can be concluded that R448A could be an energy efficient alternative to R404A with a GWP reduction of 70%. Compressor discharge temperature remains at non-dangerous levels.

Construction and testing of a transportable solar adsorption refrigerator; Construction et test d'un refrigerateur solaire a adsorption transportable

Energy Technology Data Exchange (ETDEWEB)

Mayor, J.; Dind, P.

2002-07-01

The report describes the development of an autonomous solar adsorption refrigerator characterized by its compactness and transportability. The refrigerator utilizes water as the working fluid and silicagel as the adsorbent and operates discontinuously over the day/night cycle. For a cooling volume of about 100 liters a collector-adsorber surface of 1 m{sup 2} is required and the total mass of the system amounts to about 150 kg. In order to keep its mass as low as possible the apparatus has been built with light weight materials. The cold-storage room has been insulated with a high-performance insulation material, thus minimizing thermal losses without excessively reducing the cooled volume. A new automatic valve system has been developed making superfluous any manual manipulation during normal operation. The dimensioning of the cooling system allows to cool the equivalent of 2.5 to 3.7 kg of water by 30 K daily in a climate of the Sahelien type. The cooling energy is stored in the form of ice in the evaporator and allows to bridge a period of three overcast-sky days. The construction of the solar refrigerator was made in cooperation with small regional enterprises and workshops. The cooperation with a non governmental organization allowed to test the system from May to September 2002 in a Subsaharian region of Africa where an equivalent model had been built using locally available materials. Likewise, a market study has been made in Burkina Faso in order to analyze the potential of solar adsorption refrigerators in this region. The result of the study suggests that the opening of a production workshop for such refrigerators in Burkina Faso is promising.

Numerical approach to solar ejector-compression refrigeration system

Directory of Open Access Journals (Sweden)

Zheng Hui-Fan

2016-01-01

Full Text Available A model was established for solar ejector-compression refrigeration system. The influence of generator temperature, middle-temperature, and evaporator temperature on the performance of the refrigerant system was analyzed. An optimal generator temperature is found for maximal energy efficiency ratio and minimal power consumption.

Technical potential of evaporative cooling in Danish and European condition

DEFF Research Database (Denmark)

Pomianowski, Michal Zbigniew; Andersen, Christian Hede; Heiselberg, Per Kvols

2015-01-01

Evaporative cooling is a very interesting high temperature cooling solution that has potential to save energy comparing to refrigerant cooling systems and at the same time provide more cooling reliability than mechanical or natural ventilation system without cooling. Technical cooling potential...... of 5 different evaporative systems integrated in the ventilation system is investigated in this article. Annual analysis is conducted based on hourly weather data for 15 cities located in Denmark and 123 European cities. Investigated systems are direct, indirect, combinations of direct and indirect...

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.

Cooling of superconducting devices by liquid storage and refrigeration unit

Science.gov (United States)

Laskaris, Evangelos Trifon; Urbahn, John Arthur; Steinbach, Albert Eugene

2013-08-20

A system is disclosed for cooling superconducting devices. The system includes a cryogen cooling system configured to be coupled to the superconducting device and to supply cryogen to the device. The system also includes a cryogen storage system configured to supply cryogen to the device. The system further includes flow control valving configured to selectively isolate the cryogen cooling system from the device, thereby directing a flow of cryogen to the device from the cryogen storage system.

Solar cooling systems. Classification and energetic evaluation; Solare Kuehlsysteme. Klassifizierung und energetische Bewertung

Energy Technology Data Exchange (ETDEWEB)

Hennig, Jakob [Technische Univ. Bergakademie Freiberg (Germany); Hafner, Armin [SINTEF Energy Research, Trondheim (Norway); Eikevik, Trygve M. [NTNU, Trondheim (Norway)

2012-07-01

The investigation of alternative, sustainable concepts for cold production is worthwhile in times of increasing energy demand for cooling and air conditioning applications. Energy sources such as solar radiation can help to reduce the burden on the environment and energy networks. Solar electricity from photovoltaic cells or solar power from solar collectors can be used in refrigerating equipment (such as cold vapor compression chiller, absorption chiller, adsorption chillers, open systems, thermo-mechanical systems or ejector-based systems) are fed in order to produce the desired coldness. In many cases, the temporal coincidence of radiation supply and cooling requirements makes the solar cooling to a promising concept, especially at sites with a high solar radiation, large cooling demand, high energy prices, or insufficient access to public power grids. A model-based investigation of different solar cooling systems with an equivalent cooling capacity was carried out. The results show that the performance potential strongly depends on the selected technology and the site of the system. A balanced daily energy balance can be achieved with an appropriately dimensioned solar power plant with cooling concept. Depending on the system and interpretation, primary energy savings or a primary energy overhead can be achieved within a year in comparison to a conventional system.

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.

Transition edge sensor-energy-dispersive spectrometer (TES-EDS) using a cryogen-free dilution refrigerator for material analysis

International Nuclear Information System (INIS)

Tanaka, Keiichi; Odawara, Akikazu; Nagata, Atsushi; Ikeda, Masanori; Baba, Yukari; Nakayama, Satoshi; Chinone, Kazuo

2006-01-01

A cryogen-free energy-dispersive spectrometer (EDS) using a transition edge sensor (TES) was developed for material analysis. This system can maintain a temperature at 130 mK within 30 μK, and has good energy resolution (19 eV for Mn-Kα) for long-time measurement with a drift in the DC level of less than 0.02 eV/min. This system utilizes a dilution refrigerator (φ 272 mmxheight 572 mm) and has a snout (370 mm long and φ25 mm) similar to that in a conventional EDS system. The dilution refrigerator is pre-cooled by a GM refrigerator. A flexible tube between the dilution refrigerator and GM refrigerator damps the mechanical vibration of the GM refrigerator. Two shields (4 and 80 K) thermally protect the Cu rod (φ8 mm) cooled to be 100 mK. Windows composed of polyimide+Al film allow X-ray detection above the C-Kα line. A TES (6 mmx6 mm) and array SQUID amplifier (1.5 mmx3 mm) are mounted on top of the Cu rod. For Mn-Kα, the pulse height is 5.5 μA and decay time (τ eff ) is 90 μs. The maximum count rate (1/20 τ eff ) is estimated at about 500 cps

On subcooler design for integrated two-temperature supermarket refrigeration system

Energy Technology Data Exchange (ETDEWEB)

Yang, Liang [Institute of Refrigeration and Cryogenics, Shanghai Jiaotong University, Shanghai 200240 (China); Zhang, Chun-Lu [College of Mechanical Engineering, Tongji University, No. 4800, Cao An Highway, Shanghai 201804 (China)

2011-01-15

The energy saving opportunity of supermarket refrigeration systems using subcooler between the medium-temperature (MT) refrigeration system and the low-temperature (LT) refrigeration system has been identified in the previous work. This paper presents a model-based comprehensive analysis on the subcooler design. The optimal subcooling control is discussed as well. With optimal subcooler size and subcooling control, the maximum energy savings of integrated two-temperature supermarket refrigeration system using R404A or R134a as working fluid can achieve 27% or 20%, respectively. The load ratio of MT to LT system and the operating conditions have considerable impact on the energy savings. (author)

Thermal investigations of a room temperature magnetic refrigerator

Energy Technology Data Exchange (ETDEWEB)

Smaili, Arezki; Chiba, Younes [Ecole Nationale Polytechnique d' Alger (Algeria)], email: arezki.smaili@enp.edu.dz

2011-07-01

Magnetic refrigeration is a concept based on the magnetocaloric effect that some materials exhibit when the external magnetic field changes. The aim of this paper is to assess the performance of a numerical model in predicting parameters of an active magnetic regenerator refrigerator. Numerical simulations were conducted to perform a thermal analysis on an active magnetic regenerator refrigerator operating near room temperature with and without applied cooling load. Curves of temperature span, cooling capacity and thermal efficiency as functions of the operating conditions were drawn and are presented in this paper. Results showed that at fixed frequency Ql versus mf has an optimum and COP was increased with cycle frequency values. This study demonstrated that the proposed numerical model could be used to predict parameters of an active magnetic regenerator refrigerator as it provides consistent results.

Conceptual design of a 0.1 W magnetic refrigerator for operation between 10 K and 2 K

International Nuclear Information System (INIS)

Helvensteijn, B.P.M.; Kashani, A.

1990-01-01

The design of a magnetic refrigerator for space applications is discussed. The refrigerator is to operate in the temperature range of 10 K-2 K, at a 2 K cooling power of 0.10 W. As in other magnetic refrigerators operating in this temperature range GGG has been selected as the refrigerant. Crucial to the design of the magnetic refrigerator are the heat switches at both the hot and cold ends of the GGG pill. The 2 K heat switch utilizes a narrow He II filled gap. The 10 K heat switch is based on a narrow helium gas gap. For each switch, the helium in the gap is cycled by means of activated carbon pumps. The design concentrates on reducing the switching times of the pumps and the switches as a whole. A single stage system (one magnet; one refrigerant pill) is being developed. Continuous cooling requires the fully stationary system to have at least two stages running parallel/out of phase with each other. In order to conserve energy, it is intended to recycle the magnetic energy between the magnets. To this purpose, converter networks designed for superconducting magnetic energy storage are being studied. 17 refs

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.

Model based control of refrigeration systems

Energy Technology Data Exchange (ETDEWEB)

Sloth Larsen, L.F.

2005-11-15

The subject for this Ph.D. thesis is model based control of refrigeration systems. Model based control covers a variety of different types of controls, that incorporates mathematical models. In this thesis the main subject therefore has been restricted to deal with system optimizing control. The optimizing control is divided into two layers, where the system oriented top layers deals with set-point optimizing control and the lower layer deals with dynamical optimizing control in the subsystems. The thesis has two main contributions, i.e. a novel approach for set-point optimization and a novel approach for desynchronization based on dynamical optimization. The focus in the development of the proposed set-point optimizing control has been on deriving a simple and general method, that with ease can be applied on various compositions of the same class of systems, such as refrigeration systems. The method is based on a set of parameter depended static equations describing the considered process. By adapting the parameters to the given process, predict the steady state and computing a steady state gradient of the cost function, the process can be driven continuously towards zero gradient, i.e. the optimum (if the cost function is convex). The method furthermore deals with system constrains by introducing barrier functions, hereby the best possible performance taking the given constrains in to account can be obtained, e.g. under extreme operational conditions. The proposed method has been applied on a test refrigeration system, placed at Aalborg University, for minimization of the energy consumption. Here it was proved that by using general static parameter depended system equations it was possible drive the set-points close to the optimum and thus reduce the power consumption with up to 20%. In the dynamical optimizing layer the idea is to optimize the operation of the subsystem or the groupings of subsystems, that limits the obtainable system performance. In systems

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%

Mathematical Model of a Lithium-Bromide/Water Absorption Refrigeration System Equipped with an Adiabatic Absorber

Directory of Open Access Journals (Sweden)

Salem M. Osta-Omar

2016-11-01

Full Text Available The objective of this paper is to develop a mathematical model for thermodynamic analysis of an absorption refrigeration system equipped with an adiabatic absorber using a lithium-bromide/water (LiBr/water pair as the working fluid. The working temperature of the generator, adiabatic absorber, condenser, evaporator, the cooling capacity of the system, and the ratio of the solution mass flow rate at the circulation pump to that at the solution pump are used as input data. The model evaluates the thermodynamic properties of all state points, the heat transfer in each component, the various mass flow rates, and the coefficient of performance (COP of the cycle. The results are used to investigate the effect of key parameters on the overall performance of the system. For instance, increasing the generator temperatures and decreasing the adiabatic absorber temperatures can increase the COP of the cycle. The results of this mathematical model can be used for designing and sizing new LiBr/water absorption refrigeration systems equipped with an adiabatic absorber or for optimizing existing aforementioned systems.

The cost of solar refrigeration: The rococo project; Was solare Kuehlung kostet - das Rococo-Projekt

Energy Technology Data Exchange (ETDEWEB)

Meyer, J.P.

2008-01-21

The cost of modern solar refrigerators is between 1,300 and 8,000 Euros per kW of refrigeration capacity. The biggest potential for savings is in the peripheral components, as well as in the operating cost and especially in servicing. Cost reduction must have priority if solar refrigeration is to be successful in the market. In the context of the European research project ''Reduction of costs of Solar Cooling systems'' (Rococo), a team of scientists from France, Spain and Austria investigated existing systems. (orig.)

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...

Cryogenics for the MuCool Test Area (MTA)

International Nuclear Information System (INIS)

Darve, Christine; Norris, Barry; Pei, Liujin

2006-01-01

MuCool Test Area (MTA) is a complex of buildings at Fermi National Accelerator Laboratory, which are dedicated to operate components of a cooling cell to be used for Muon Collider and Neutrino Factory R and D. The long-term goal of this facility is to test ionization cooling principles by operating a 25-liter liquid hydrogen (LH2) absorber embedded in a 5 Tesla superconducting solenoid magnet. The MTA solenoid magnet will be used with RF cavities exposed to a high intensity beam. Cryogens used at the MTA include LHe, LN2 and LH2. The latter dictates stringent system design for hazardous locations. The cryogenic plant is a modified Tevatron refrigerator based on the Claude cycle. The implementation of an in-house refrigerator system and two 300 kilowatt screw compressors is under development. The helium refrigeration capacity is 500 W at 14 K. In addition the MTA solenoid magnet will be batch-filled with LHe every 2 days using the same cryo-plant. This paper reviews cryogenic systems used to support the Muon Collider and Neutrino Factory R and D programs and emphasizes the feasibility of handling cryogenic equipment at MTA in a safe manner

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.

Control Methods Utilizing Energy Optimizing Schemes in Refrigeration Systems

DEFF Research Database (Denmark)

Larsen, L.S; Thybo, C.; Stoustrup, Jakob

2003-01-01

The potential energy savings in refrigeration systems using energy optimal control has been proved to be substantial. This however requires an intelligent control that drives the refrigeration systems towards the energy optimal state. This paper proposes an approach for a control, which drives th...... the condenser pressure towards an optimal state. The objective of this is to present a feasible method that can be used for energy optimizing control. A simulation model of a simple refrigeration system will be used as basis for testing the control method....

The effect of coolants on the performance of magnetic micro-refrigerators.

Science.gov (United States)

Silva, D J; Bordalo, B D; Pereira, A M; Ventura, J; Oliveira, J C R E; Araújo, J P

2014-06-01

Magnetic refrigeration is an alternative cooling technique with envisaged technological applications on micro- and opto-electronic devices. Here, we present a magnetic micro-refrigerator cooling device with embedded micro-channels and based on the magnetocaloric effect. We studied the influence of the coolant fluid in the refrigeration process by numerically simulating the heat transfer processes using the finite element method. This allowed us to calculate the cooling power of the device. Our results show that gallium is the most efficient coolant fluid and, when used with Gd5Si2Ge2, a maximum power of 11.2 W/mm3 at a working frequency of -5 kHz can be reached. However, for operation frequencies around 50 Hz, water is the most efficient fluid with a cooling power of 0.137 W/mm3.

Simulation of the SSC refrigeration system using the ASPEN/SP process simulator

International Nuclear Information System (INIS)

Rasson, J.; Dweck, J.

1990-01-01

The SSC Magnet must be maintained at a superconducting temperature of 4 K. The proposed refrigeration cooling processes consist of fairly simple closed cycles which take advantage of the Joule-Thompson effect via a series of expansions and compressions of helium gas which has been precooled by liquid nitrogen. The processes currently under consideration consist of three cycles, the 20 K shield cooling, the 4.0 K helium refrigerator and the helium liquefier. The process units which are to be employed are compressors, turbines, expanders, mixers, flashes, two stream heat exchangers and multiple stream heat exchangers. The cycles are to be operated at or near steady state. Due to the large number of competing cooling sector designs to be considered and the high capital and operating costs of the proposed processes, the SSC Laboratory requires a software tool for the validation and optimization of the individual designs and for the performance of cost-benefit analyses among competing designs. Since these processes are steady state flow processes involving primarily standard unit operations, a decision was made to investigate the application of a commercial process simulator to the task. Several months of internal evaluations by the SSC Laboratory revealed that while the overall structure and calculation approach of a number of the commercial simulators were appropriate for this task, all were lacking essential capabilities in the areas of thermodynamic property calculations for cryogenic systems and modeling of complex, multiple stream heat exchangers. An acceptable thermodynamic model was provided and a series of simple, but three software vendors. Based on the results of the benchmark tests, the ASPEN/SP process simulator was selected for future modeling work. 2 refs., 4 figs

A review of thermoelectric cooling: Materials, modeling and applications

International Nuclear Information System (INIS)

Zhao, Dongliang; Tan, Gang

2014-01-01

This study reviews the recent advances of thermoelectric materials, modeling approaches, and applications. Thermoelectric cooling systems have advantages over conventional cooling devices, including compact in size, light in weight, high reliability, no mechanical moving parts, no working fluid, being powered by direct current, and easily switching between cooling and heating modes. In this study, historical development of thermoelectric cooling has been briefly introduced first. Next, the development of thermoelectric materials has been given and the achievements in past decade have been summarized. To improve thermoelectric cooling system's performance, the modeling techniques have been described for both the thermoelement modeling and thermoelectric cooler (TEC) modeling including standard simplified energy equilibrium model, one-dimensional and three-dimensional models, and numerical compact model. Finally, the thermoelectric cooling applications have been reviewed in aspects of domestic refrigeration, electronic cooling, scientific application, and automobile air conditioning and seat temperature control, with summaries for the commercially available thermoelectric modules and thermoelectric refrigerators. It is expected that this study will be beneficial to thermoelectric cooling system design, simulation, and analysis. - Highlights: •Thermoelectric cooling has great prospects with thermoelectric material's advances. •Modeling techniques for both thermoelement and TEC have been reviewed. •Principle thermoelectric cooling applications have been reviewed and summarized

Silicon spectrometer with a Peltier refrigerator

International Nuclear Information System (INIS)

Belcarz, E.; Chwaszczewska, J.; Hahn, G.; Nowicki, W.; Sawicka, B.; Skoczek, K.; Slapa, M.; Szymczak, M.

1974-01-01

This paper describes a spectrometer with a Si(Li) detector cooled by a Peltier refrigerator. The spectrometer is able to analyse samples of practically all most frequently encountered emitters of alpha, beta and low energy gamma radiation. The energy resolution were about 1.3-1.5 keV for 14 keV gamma radiation. The system can also operate in field conditions in the fluorescence analysis. (author)

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.

Thermal and economical optimization of air conditioning units with vapor compression refrigeration system

Energy Technology Data Exchange (ETDEWEB)

Sanaye, S.; Malekmohammadi, H.R. [Iran University of Science and Technology, Tehran (Iran). Dept. of Mechanical Engineering

2004-09-01

A new method of thermal and economical optimum design of air conditioning units with vapor compression refrigeration system, is presented. Such a system includes compressor, condenser, evaporator, centrifugal and axial fans. Evaporator and condenser temperatures, their heating surface areas (frontal surface area and number of tubes), centrifugal and axial fan powers, and compressor power are among the design variables. The data provided by manufacturers for fan (volume flow rate versus pressure drop) and compressor power (using evaporator and condenser temperatures) was used to choose these components directly from available data for consumers. To study the performance of the system under various situations, and implementing the optimization procedure, a simulation program including all thermal and geometrical parameters was developed. The objective function for optimization was the total cost per unit cooling load of the system including capital investment for components as well as the required electricity cost. To find the system design parameters, this objective function was minimized by Lagrange multipliers method. The effects of changing the cooling load on optimal design parameters were studied. (author)

A new boil-off gas re-liquefaction system for LNG carriers based on dual mixed refrigerant cycle

Science.gov (United States)

Tan, Hongbo; Shan, Siyu; Nie, Yang; Zhao, Qingxuan

2018-06-01

A new boil-off gas (BOG) re-liquefaction system for LNG carriers has been proposed to improve the system energy efficiency. Two cascade mixed refrigerant cycles (or dual mixed refrigerant cycle, DMR) are used to provide the cooling capacity for the re-liquefaction of BOG. The performance of the new system is analysed on the basis of the thermodynamic data obtained in the process simulation in Aspen HYSYS software. The results show that the power consumed in the BOG compressor and the high-temperature mixed refrigerant compressor could be saved greatly due to the reduced mass flow rates of the processed fluids. Assuming the re-liquefaction capacity of the investigated system is 4557.6 kg/h, it is found that the total power consumption can be reduced by 25%, from 3444 kW in the existing system to 2585.8 kW in the proposed system. The coefficient of performance (COP) of 0.25, exergy efficiency of 41.3% and the specific energy consumption (SEC) of 0.589 kWh/kg(LNG) could be achieved in the new system. It exhibits 33% of improvement in the COP and exergy efficiency in comparison with the corresponding values of the existing system. It indicates that employing the DMR based BOG re-liquefaction system could improve the system energy efficiency of LNG carriers substantially.

Development of 18 K helium refrigeration system for CERN

CERN Document Server

CERN. Geneva

2004-01-01

The Conseil Europeen pour Ia Recherche Nucleaire (CERN) placed an order for a 1.8 K helium refrigeration system with IHI for the Large Hadron Collider project in 1999. IHI formed a consortium with Linde Kryotechnik AG (Switzerland), which has long experience with helium refrigeration systems. IHI designed and manufactured cold compressors based on leading technologies and expertise for turbo machinery. The cold compressor has the highest efficiency in the world. This paper describes the 1.8 K helium refrigeration system and performance test results at CERN. (5 refs).

Solar thermally driven cooling systems: Some investigation results and perspectives

International Nuclear Information System (INIS)

Ajib, Salman; Günther, Wolfgang

2013-01-01

Highlights: ► Two types of solar thermally driven absorption refrigeration machines (ARMs) have been investigated. ► We investigated the influence of the operating conditions on the effectiveness of the ARMs. ► The influence of the flow rate of the work solution on the effectiveness of the ARMs has been tested. ► Two laboratory test plants have been built and tested under different operating conditions. - Abstract: A big increase in the number of solar thermal cooling installations and research efforts could be seen over the last years worldwide. Especially the producers of solar thermal collectors and systems have been looking for thermal chillers in the small capacity range to provide air conditioning for one or two family houses. Furthermore, many developments aim to increase the efficiency of the system and to decrease the specific costs of the produced refrigeration capacity. The growth in the use of solar thermal cooling systems amounted about 860% from 52 units in 2004 to 450 units in 2009 [1]. This tendency is expected to be continuously in the next years. The practical examinations on solar thermally driven absorption machines with refrigeration capacity of 15, 10 and 5 kW have shown that this technology has a good chance to be standardized and to replace partly the conventional one. These systems can save more primary energy at high fraction of solar thermally driving by suitable control and regulation of the system. The investing costs still higher as the conventional one, however, the operating costs are less than the conventional one. The Coefficient of Performance (COP) depends on the kind of the system, work temperatures and conditions as well as the refrigeration capacity of the systems. It lies between 0.4 and 1.2. In the framework of the research on this field, we built, tested and measured two prototypes. After measuring the first prototype, the chillers were redesigned to reduce internal heat losses and make the heat and mass transfer

Natural gas cooling: Part of the solution

International Nuclear Information System (INIS)

Jones, D.R.

1992-01-01

This paper reviews and compares the efficiencies and performance of a number of gas cooling systems with a comparable electric cooling system. The results show that gas cooling systems compare favorably with the electric equivalents, offering a new dimension to air conditioning and refrigeration systems. The paper goes on to compare the air quality benefits of natural gas to coal or oil-burning fuel systems which are used to generate the electricity for the electric cooling systems. Finally, the paper discusses the regulatory bias that the author feels exists towards the use of natural gas and the need for modification in the existing regulations to provide a 'level-playing field' for the gas cooling industry

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%.

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.

Defrost Temperature Termination in Supermarket Refrigeration Systems

Energy Technology Data Exchange (ETDEWEB)

Fricke, Brian A [ORNL; Sharma, Vishaldeep [ORNL

2011-11-01

The objective of this project was to determine the potential energy savings associated with implementing demand defrost strategies to defrost supermarket refrigerated display case evaporators, as compared to the widely accepted current practice of controlling display case defrost cycles with a preset timer. The defrost heater energy use of several representative display case types was evaluated. In addition, demand defrost strategies for refrigerated display cases as well as those used in residential refrigerator/freezers were evaluated. Furthermore, it is anticipated that future work will include identifying a preferred defrost strategy, with input from Retail Energy Alliance members. Based on this strategy, a demand defrost system will be designed which is suitable for supermarket refrigerated display cases. Limited field testing of the preferred defrost strategy will be performed in a supermarket environment.

Optimal analysis of gas cooler and intercooler for two-stage CO2 trans-critical refrigeration system

International Nuclear Information System (INIS)

Li, Wenhua

2013-01-01

Highlights: • Simplified model for tube-fin gas cooler for CO 2 refrigeration system was presented and validated. • Several parameters were investigated using 1st law and 2nd law in component and system level. • Practical guidelines of optimum for tube-fin gas cooler and intercooler were proposed. - Abstract: Energy-based 1st law and exergy-based 2nd law are both employed in the paper to assess the optimal design of gas cooler and intercooler for two-stage CO 2 refrigeration system. A simplified mathematical model of the air-cooled coil is presented and validated against experimental data with good accuracy. The optimum circuit length under the influence of frontal air velocity and deep rows is investigated first. Thereafter, designed coil with optimum circuit length is further evaluated within the two-stage refrigeration system. It is found out the optimum point using 1st law does not coincide with the point using 2nd law in isolated component and the simulation results from isolated component by 2nd law are closer to system analysis. Results show optimum circuit length is much bigger for gas cooler than intercooler and the influence on the length from variation of frontal air velocity and deep rows may be neglected. There does exist optimum frontal air velocity which will decrease with more number of deep rows

Cryogenic refrigeration requirements for superconducting insertion devices in a light source

International Nuclear Information System (INIS)

Green, Michael A.; Green, Michael A.; Green, Michael A.

2003-01-01

This report discusses cryogenic cooling superconducting insertion devices for modern light sources. The introductory part of the report discusses the difference between wiggler and undulators and how the bore temperature may affect the performance of the magnets. The steps one would take to reduce the gap between the cold magnet pole are discussed. One section of the report is devoted to showing how one would calculate the heat that enters the device. Source of heat include, heat entering through the vacuum chamber, heating due to stray electrons and synchrotron radiation, heating due to image current on the bore, heat flow by conduction and radiation, and heat transfer into the cryostat through the magnet leads. A section of the report is devoted to cooling options such as small cryo-cooler and larger conventional helium refrigerators. This section contains a discussion as to when it is appropriate to use small coolers that do not have J-T circuits. Candidate small cryo-coolers are discussed in this section of the report. Cooling circuits for cooling with a conventional refrigerator are also discussed. A section of the report is devoted to vibration isolation and how this may affect how the cooling is attached to the device. Vibration isolation using straps is compared to vibration isolation using helium heat pipes. The vibration isolation of a conventional refrigeration system is also discussed. Finally, the cool down of an insertion device is discussed. The device can either be cooled down using liquid cryogenic nitrogen and liquid helium or by using the cooler used to keep the devices cold over the long haul

Cycle Design of Reverse Brayton Cryocooler for HTS Cable Cooling Using Exergy Analysis

Science.gov (United States)

Gupta, Sudeep Kumar; Ghosh, Parthasarathi

2017-02-01

The reliability and price of cryogenic refrigeration play an important role in the successful commercialization of High Temperature Superconducting (HTS) cables. For cooling HTS cable, sub-cooled liquid nitrogen (LN2) circulation system is used. One of the options to maintain LN2 in its sub-cooled state is by providing refrigeration with the help of Reverse Brayton Cryo-cooler (RBC). The refrigeration requirement is 10 kW for continuously sub-cooling LN2 from 72 K to 65 K for cooling 1 km length of HTS cable [1]. In this paper, a parametric evaluation of RBC for sub-cooling LN2 has been performed using helium as a process fluid. Exergy approach has been adopted for this analysis. A commercial process simulator, Aspen HYSYS® V8.6 has been used for this purpose. The critical components have been identified and their exergy destruction and exergy efficiency have been obtained for a given heat load condition.

The performance of a mobile air conditioning system with a water cooled condenser

International Nuclear Information System (INIS)

Di Battista, Davide; Cipollone, Roberto

2015-01-01

Vehicle technological evolution lived, in recent years, a strong acceleration due to the increased awareness of environmental issues related to pollutants and climate altering emissions. This resulted in a series of international regulations on automotive sector which put technical challenges that must consider the engine and the vehicle as a global system, in order to improve the overall efficiency of the system. The air conditioning system of the cabin, for instance, is the one of the most important auxiliaries in a vehicle and requires significant powers. Its performances can be significantly improved if it is integrated within the engine cooling circuit, eventually modified with more temperature levels.In this paper, the Authors present a mathematical model of the A/C system, starting from its single components: compressors, condenser, flush valve and evaporator and a comparison between different refrigerant fluid. In particular, it is introduced the opportunity to have an A/C condenser cooled by a water circuit instead of the external air linked to the vehicle speed, as in the actual traditional configuration. The A/C condenser, in fact, could be housed on a low temperature water circuit, reducing the condensing temperature of the refrigeration cycle with a considerable efficiency increase. (paper)

The performance of a mobile air conditioning system with a water cooled condenser

Science.gov (United States)

Di Battista, Davide; Cipollone, Roberto

2015-11-01

Vehicle technological evolution lived, in recent years, a strong acceleration due to the increased awareness of environmental issues related to pollutants and climate altering emissions. This resulted in a series of international regulations on automotive sector which put technical challenges that must consider the engine and the vehicle as a global system, in order to improve the overall efficiency of the system. The air conditioning system of the cabin, for instance, is the one of the most important auxiliaries in a vehicle and requires significant powers. Its performances can be significantly improved if it is integrated within the engine cooling circuit, eventually modified with more temperature levels. In this paper, the Authors present a mathematical model of the A/C system, starting from its single components: compressors, condenser, flush valve and evaporator and a comparison between different refrigerant fluid. In particular, it is introduced the opportunity to have an A/C condenser cooled by a water circuit instead of the external air linked to the vehicle speed, as in the actual traditional configuration. The A/C condenser, in fact, could be housed on a low temperature water circuit, reducing the condensing temperature of the refrigeration cycle with a considerable efficiency increase.

Magnetic refrigeration down to 1.6 K for the future circular collider e$^+$e$^-$

CERN Document Server

Tkaczuk, Jakub; Millet, Francois; Rousset, Bernard; Duval, Jean Marc

2017-01-01

High-field superconducting rf cavities of the future circular collider e+e− may require a kW-range superfluid helium refrigeration down to 1.6 K. Magnetic refrigeration operating below 4.2 K can be an alternative to the compression/expansion helium refrigeration. A significant difference between this application and previous magnetic refrigerator studies is its large cooling power, up to 103 times larger than the other designs. Principles of magnetic refrigeration are described and various technical solutions are compared. A numerical model for the static magnetic refrigerator is presented, validated, and adapted to the needs of the positron-electron version of the future circular collider. A preliminary design of magnetic refrigerator suitable for low temperature, kW-range cooling is studied.

Mechanical vapor compression refrigeration for low temperature industrial applications today

International Nuclear Information System (INIS)

Ferguson, J.E.

1987-01-01

If the super conductor industry settles out at a temperature of -100 0 F or above, mechanical refrigeration will be vying for the cooling business. Today there very definitely is a break point in the application of equipment at approximately -120 0 F or 189 0 K. Other technologies are generally utilized below this level. However, with market potential comes invention and breakthroughs in refrigeration can also occur. Today standard refrigeration systems are cost effective, reliable and produced in the millions for high temperature applications of +10 0 F to +40 0 F evaporator temperature. Lower temperatures require additional hardware, consume additional power and are produced today in limited quantities for special applications

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.

Modelling and simulation of regenerators with complex flow arrangements for active magnetocaloric refrigeration

DEFF Research Database (Denmark)

Lei, Tian; Nielsen, Kaspar Kirstein; Engelbrecht, Kurt

2014-01-01

Compared to a conventional vapor compression refrigera-tion system, a magnetocaloric refrigerator has many advantages, such as potentially high efficiency, low vibration and avoidance of refrigerants that deplete the ozone layer and cause the green-house effect. As a main component of the active...... magnetic re-generative refrigerator, the regenerator plays an important role in the cooling performance and efficiency of the whole system. However, the regenerator design is constrained by several exter-nal factors, such as the geometry of the magnetic field source and flow resistance. In this work, novel...... regenerators with complex flow arrange-ments, providing high performance at lower pressure drop, are investigated. Correspondingly a one dimensional model is pre-sented and comparative studies between novel and conventional regenerators are carried out by simulation. The effect of regen-erator geometries...

Energy analysis of a supermarket refrigeration system

DEFF Research Database (Denmark)

Jensen, Jakob Munch; Jakobsen, Arne; Rasmussen, Bjarne D.

1999-01-01

From 1995 to 1998, an energy test method for supermarket refrigeration systems was developed in a project financed by the Danish Energy Agency. The purpose of the energy test method is to provide the means for evaluating the energy efficiency of these systems. The test method requires measurements...... of air temperatures and energy consumption to be carried out on the selected supermarket refrigeration system. In addition to the measurements required by the method, more measurements of individual energy consumptions have been carried in the case described in this paper. The purpose of the additional...

Systematic modelling and simulation of refrigeration systems

DEFF Research Database (Denmark)

Rasmussen, Bjarne D.; Jakobsen, Arne

1998-01-01

The task of developing a simulation model of a refrigeration system can be very difficult and time consuming. In order for this process to be effective, a systematic method for developing the system model is required. This method should aim at guiding the developer to clarify the purpose...... of the simulation, to select appropriate component models and to set up the equations in a well-arranged way. In this paper the outline of such a method is proposed and examples showing the use of this method for simulation of refrigeration systems are given....

Modeling the dynamic response of pressures in a distributed helium refrigeration system

International Nuclear Information System (INIS)

Brubaker, J.C.

1997-12-01

A mathematical model is created of the dynamic response of pressures caused by flow inputs to an existing distributed helium refrigeration system. The dynamic system studied consists of the suction and discharge pressure headers and compressor portions of the refrigeration system used to cool the superconducting magnets of the Tevatron accelerator at the Fermi National Accelerator Laboratory. The modeling method involves identifying the system from data recorded during a series of controlled tests, with effort made to detect locational differences in pressure response around the four mile accelerator circumference. A review of the fluid mechanics associated with the system indicates linear time invariant models are suitable for the identification, particularly since the governing equations of one dimensional fluid flow are approximated by linear differential equations. An outline of the experimental design and the data acquisition system are given, followed by a detailed description of the modeling, which utilized the Matlab programming language and associated System Identification Toolbox. Two representations of the system are presented. One, a black box model, provides a multi-input, multi-output description assembled from the results of single input step function testing. This description indicates definite variation in pressure response with distance from the flow input location, and also suggests subtle differences in response with the input location itself. A second system representation is proposed which details the relation between continuous flow changes and pressure response, and provides explanation of a previously unappreciated pressure feedback internal to the system

Modeling the dynamic response of pressures in a distributed helium refrigeration system

Energy Technology Data Exchange (ETDEWEB)

Brubaker, John Carl [Illinois Inst. of Technology, Chicago, IL (United States)

1997-12-01

A mathematical model is created of the dynamic response of pressures caused by flow inputs to an existing distributed helium refrigeration system. The dynamic system studied consists of the suction and discharge pressure headers and compressor portions of the refrigeration system used to cool the superconducting magnets of the Tevatron accelerator at the Fermi National Accelerator Laboratory. The modeling method involves identifying the system from data recorded during a series of controlled tests, with effort made to detect locational differences in pressure response around the four mile accelerator circumference. A review of the fluid mechanics associated with the system indicates linear time invariant models are suitable for the identification, particularly since the governing equations of one dimensional fluid flow are approximated by linear differential equations. An outline of the experimental design and the data acquisition system are given, followed by a detailed description of the modeling, which utilized the Matlab programming language and associated System Identification Toolbox. Two representations of the system are presented. One, a black box model, provides a multi-input, multi-output description assembled from the results of single input step function testing. This description indicates definite variation in pressure response with distance from the flow input location, and also suggests subtle differences in response with the input location itself. A second system representation is proposed which details the relation between continuous flow changes and pressure response, and provides explanation of a previously unappreciated pressure feedback internal to the system.

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

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)

Experimental investigation on motive nozzle throat diameter for an ejector expansion refrigeration system

International Nuclear Information System (INIS)

Bilir Sag, Nagihan; Ersoy, H. Kursad

2016-01-01

Highlights: • Effects of nozzle throat diameter and its location on performance were investigated. • The nozzle has an optimum throat diameter under the experiment condition. • The maximum performance has been achieved by using optimum nozzle throat diameter. • The variation of nozzle throat diameter with condenser water inlet temperature was examined. • Motive nozzle has no optimum position in the ejector refrigeration system. - Abstract: In this study, ejector was used to reduce throttling losses in a vapour compression refrigeration system. Effects on system performance of throat diameter and position of motive nozzle of ejector were investigated experimentally. An ejector was designed based on the established mathematical model and manufactured. The experiments were carried out by using different primary nozzle throat diameters. The experiments were further conducted by changing condenser water inlet temperature, which is one of the external parameters. The experimental results of the ejector system and those of the classic system were compared under same external operating conditions and for the same cooling capacity. In order to obtain same external operating conditions in both systems, the inlet conditions of the brine supplied to the evaporator and inlet water conditions (flow rate and temperature) to the condenser were kept constant. Maximum performance was obtained when the primary nozzle throat diameter was 2.3 mm within the areas considered in this study. When compared, it was experimentally determined that the ejector system that uses the optimum motive nozzle throat diameter exhibits higher COP than the classic system by 5–13%. Furthermore, it was found that the variation of coefficient of performance based on position of motive nozzle in two-phase ejector expander refrigeration cycle is lower than 1%.

Performance Analysis of Multipurpose Refrigeration System (MRS on Fishing Vessel

Directory of Open Access Journals (Sweden)

Ust Y.

2016-04-01

Full Text Available The use of efficient refrigerator/freezers helps considerably to reduce the amount of the emitted greenhouse gas. A two-circuit refrigerator-freezer cycle (RF reveals a higher energy saving potential than a conventional cycle with a single loop of serial evaporators, owing to pressure drop in each evaporator during refrigeration operation and low compression ratio. Therefore, several industrial applications and fish storage systems have been utilized by using multipurpose refrigeration cycle. That is why a theoretical performance analysis based on the exergetic performance coefficient, coefficient of performance (COP, exergy efficiency and exergy destruction ratio criteria, has been carried out for a multipurpose refrigeration system by using different refrigerants in serial and parallel operation conditions. The exergetic performance coefficient criterion is defined as the ratio of exergy output to the total exergy destruction rate (or loss rate of availability. According to the results of the study, the refrigerant R32 shows the best performance in terms of exergetic performance coefficient, COP, exergy efficiency, and exergy destruction ratio from among the other refrigerants (R1234yf, R1234ze, R404A, R407C, R410A, R143A and R502. The effects of the condenser, freezer-evaporator and refrigerator-evaporator temperatures on the exergetic performance coefficient, COP, exergy efficiency and exergy destruction ratios have been fully analyzed for the refrigerant R32.

The refrigerant plant engineer. Vol. 2. Application of coldness. 4. new rev. and enl. ed.; Der Kaelteanlagenbauer. Bd. 2. Kaelteanwendungen

Energy Technology Data Exchange (ETDEWEB)

Breidenbach, Karl

2004-07-01

Specialists within the range of the refrigerant plant engineering need comprehensive knowledge in the everyday life of occupation. The standard work under consideration very vividly offers an introduction to the technology of refrigerant plants. The second volume of this standard work contains the following chapters: Evaporator; Air cooler and liquid cooler; Air humidification in the cooled room; Condensor; Evaporation cooler and hybrid cooler, cooling towers; Refrigeration compressor; Coolant filling material; Two-phase coolant (binary ice); Water cooling machine with water as refrigerants; Fluid mechanical fundamentals; Expansion valves; Control and adjustment of refrigerant plants; Dimensioning of components; Planning fundamentals; Dimensioning of refrigerant leading pipes for refrigerants.

Modular Modelling and Simulation Approach - Applied to Refrigeration Systems

DEFF Research Database (Denmark)

Sørensen, Kresten Kjær; Stoustrup, Jakob

2008-01-01

This paper presents an approach to modelling and simulation of the thermal dynamics of a refrigeration system, specifically a reefer container. A modular approach is used and the objective is to increase the speed and flexibility of the developed simulation environment. The refrigeration system...

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.

Component-wise exergy and energy analysis of vapor compression refrigeration system using mixture of R134a and LPG as refrigerant

Science.gov (United States)

Gill, Jatinder; Singh, Jagdev

2017-11-01

In this work, the experimental examination was carried out using a mixture of R134a and LPG refrigerant (consisting of R134a and LPG in a proportion of 28:72 by weight) as a replacement for R134a in a vapor compression refrigeration system. Exergy and energy tests were carried out at different evaporator and condenser temperatures with controlled environmental conditions. The results showed that the exergy destruction in the compressor, condenser, evaporator, and a capillary tube of the R134a / LPG refrigeration system was found lower by approximately 11.13-3.41%, 2.24-3.43%, 12.02-13.47% and 1.54-5.61% respectively. The compressor exhibits the highest level of destruction, accompanied by a condenser, an evaporator and a capillary tube in refrigeration systems. The refrigeration capacity, COP and power consumption of the compressor of the R134a /LPG refrigeration system were detected higher and lower compared to the R134a refrigeration system by about 7.04-11.41%, 15.1-17.82%, and 3.83-8.08% respectively. Also, the miscibility of R134a and LPG blend with mineral oil discovered good. The R134a and LPG refrigerant mixture proposed in this study perform superior to R134a from component-wise exergy and energy analyses under similar experimental conditions.

Component-wise exergy and energy analysis of vapor compression refrigeration system using mixture of R134a and LPG as refrigerant

Science.gov (United States)

Gill, Jatinder; Singh, Jagdev

2018-05-01

In this work, the experimental examination was carried out using a mixture of R134a and LPG refrigerant (consisting of R134a and LPG in a proportion of 28:72 by weight) as a replacement for R134a in a vapor compression refrigeration system. Exergy and energy tests were carried out at different evaporator and condenser temperatures with controlled environmental conditions. The results showed that the exergy destruction in the compressor, condenser, evaporator, and a capillary tube of the R134a / LPG refrigeration system was found lower by approximately 11.13-3.41%, 2.24-3.43%, 12.02-13.47% and 1.54-5.61% respectively. The compressor exhibits the highest level of destruction, accompanied by a condenser, an evaporator and a capillary tube in refrigeration systems. The refrigeration capacity, COP and power consumption of the compressor of the R134a /LPG refrigeration system were detected higher and lower compared to the R134a refrigeration system by about 7.04-11.41%, 15.1-17.82%, and 3.83-8.08% respectively. Also, the miscibility of R134a and LPG blend with mineral oil discovered good. The R134a and LPG refrigerant mixture proposed in this study perform superior to R134a from component-wise exergy and energy analyses under similar experimental conditions.

A Cold Cycle Dilution Refrigerator for Space Applications, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — The cold cycle dilution refrigerator is a continuous refrigerator capable of cooling to temperatures below 100 mK that makes use of a novel thermal magnetic pump....

Design-theoretical study of cascade CO2 sub-critical mechanical compression/butane ejector cooling cycle

KAUST Repository

Petrenko, V.O.

2011-11-01

In this paper an innovative micro-trigeneration system composed of a cogeneration system and a cascade refrigeration cycle is proposed. The cogeneration system is a combined heat and power system for electricity generation and heat production. The cascade refrigeration cycle is the combination of a CO2 mechanical compression refrigerating machine (MCRM), powered by generated electricity, and an ejector cooling machine (ECM), driven by waste heat and using refrigerant R600. Effect of the cycle operating conditions on ejector and ejector cycle performances is studied. Optimal geometry of the ejector and performance characteristics of ECM are determined at wide range of the operating conditions. The paper also describes a theoretical analysis of the CO2 sub-critical cycle and shows the effect of the MCRM evaporating temperature on the cascade system performance. The obtained data provide necessary information to design a small-scale cascade system with cooling capacity of 10 kW for application in micro-trigeneration systems. © 2010 Elsevier Ltd and IIR. All rights reserved.

Turbine airfoil cooling system with cooling systems using high and low pressure cooling fluids

Science.gov (United States)

Marsh, Jan H.; Messmann, Stephen John; Scribner, Carmen Andrew

2017-10-25

A turbine airfoil cooling system including a low pressure cooling system and a high pressure cooling system for a turbine airfoil of a gas turbine engine is disclosed. In at least one embodiment, the low pressure cooling system may be an ambient air cooling system, and the high pressure cooling system may be a compressor bleed air cooling system. In at least one embodiment, the compressor bleed air cooling system in communication with a high pressure subsystem that may be a snubber cooling system positioned within a snubber. A delivery system including a movable air supply tube may be used to separate the low and high pressure cooling subsystems. The delivery system may enable high pressure cooling air to be passed to the snubber cooling system separate from low pressure cooling fluid supplied by the low pressure cooling system to other portions of the turbine airfoil cooling system.

Laser cooling of solids

CERN Document Server

Petrushkin, S V

2009-01-01

Laser cooling is an important emerging technology in such areas as the cooling of semiconductors. The book examines and suggests solutions for a range of problems in the development of miniature solid-state laser refrigerators, self-cooling solid-state lasers and optical echo-processors. It begins by looking at the basic theory of laser cooling before considering such topics as self-cooling of active elements of solid-state lasers, laser cooling of solid-state information media of optical echo-processors, and problems of cooling solid-state quantum processors. Laser Cooling of Solids is an important contribution to the development of compact laser-powered cryogenic refrigerators, both for the academic community and those in the microelectronics and other industries. Provides a timely review of this promising field of research and discusses the fundamentals and theory of laser cooling Particular attention is given to the physics of cooling processes and the mathematical description of these processes Reviews p...

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.

Liquid over-feeding air conditioning system and method

Science.gov (United States)

Mei, Viung C.; Chen, Fang C.

1993-01-01

A refrigeration air conditioning system utilizing a liquid over-feeding operation is described. A liquid refrigerant accumulator-heat exchanger is placed in the system to provide a heat exchange relationship between hot liquid refrigerant discharged from condenser and a relatively cool mixture of liquid and vaporous refrigerant discharged from the evaporator. This heat exchange relationship substantially sub-cools the hot liquid refrigerant which undergoes little or no evaporation across the expansion device and provides a liquid over-feeding operation through the evaporator for effectively using 100 percent of evaporator for cooling purposes and for providing the aforementioned mixture of liquid and vaporous refrigerant.

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

Thermal and hydraulic analyses of TFTR cooling water system and magnetic field coils

International Nuclear Information System (INIS)

Lee, A.Y.

1975-10-01

The TFTR toroidal field coils, ohmic heating, hybrid and equilibrium field coils are cooled by water from the machine area cooling water system. The system has the following major equipment and capacities: flow rate of 3600 gpm; ballast tank volume of 5500 gal; pumps of 70.4 m head; chiller refrigeration rating of 3300 tons and connecting pipe of 45.7 cm I.D. The performance of the closed loop system was analyzed and found to be adequate for the thermal loads. The field coils were analyzed with detailed thermal and hydraulic models, including a simulation of the complete water cooling loop. Under the nominal operating mode of one second of toroidal field flat top time and 300 seconds of pulse cycle time, the maximum temperature for the TF coils is 53 0 C; for the OH coils 46 0 C and for the EF coils 39 0 C, which are well below the coil design limit of 120 0 C. The maximum TF coil coolant temperature is 33 0 C which is below the coolant design limit of 100 0 C. The overall pressure loss of the system is below 6.89 x 10 5 Pa (100 psi). With the given chiller refrigeration capacity, the TF coils can be operated to yield up to 4 seconds of flat top time. The TF coils can be operated on a steady state basis at up to 20% of the pulsed duty design current rating of 7.32 kA/coil

Experimental Validation of the Simulation Model of a DOAS Equipped with a Desiccant Wheel and a Vapor Compression Refrigeration System

Directory of Open Access Journals (Sweden)

Pedro J. Martínez

2017-09-01

Full Text Available A dedicated outdoor air system (DOAS can be designed to supply 100% of the outside air and meet the latent load of the room with dry air. The objectives of this study were to develop a model of a DOAS equipped with a desiccant wheel and a vapor-compression refrigeration system, build a prototype, validate the model with experimental data, and gain knowledge about the system operation. The test facility was designed with the desiccant wheel downstream of the cooling coil to take advantage of the operating principles of cooling coils and desiccants. A model of the DOAS was developed in the TRNSYS environment. The root mean standard error (RMSE was used for model validation by comparing the measured air and refrigerant properties with the corresponding calculated values. The results obtained with the developed model showed that the DOAS was able to maintain an indoor humidity ratio depending on outdoor conditions. Laboratory tests were also used to investigate the effect of changes in the regeneration air temperature and the process airflow rate on the process air humidity ratio at the outlet of the wheel. The results are consistent with the technical literature.

MEPR versus EEPR valves in open supermarket refrigerated display cabinets

International Nuclear Information System (INIS)

Tahir, A.; Bansal, P.K.

2005-01-01

This paper presents the comparative experimental field performance of mechanical evaporator pressure regulating valves (MEPR) and electronic evaporator pressure regulating valves (EEPR) under the identical operating conditions of supermarket open multi-deck refrigerated display cabinets. The main goal of the supermarket refrigeration system design is to keep the displayed product at the required constant temperature, while minimising the cooling load to increase the overall energy efficiency of the system. Field tests have shown that the electronic evaporator pressure valve has a significant effect on improving the cabinet temperature and reducing the rate of frost formation on the evaporator coils with subsequent improvements in the air curtain strength

Commissioning and operation of the CEBAF end station refrigeration system

International Nuclear Information System (INIS)

Arenius, D.; Bevins, B.; Chronis, W.C.; Ganni, V.

1996-01-01

The CEBAF End Station Helium Refrigerator (ESR) System provides refrigeration at 80 K, 20 K and 4.5 K to three End Station experimental halls. The facility consists of a two stage helium screw compressor system, 4.5 K refrigerator, cryogen distribution valve box, and transfer lines to the individual experimental halls. The 4.5 K cold box and compressors were originally part of the ESCAR 1500 W, 4 K refrigeration system at Lawrence Berkeley Laboratory which was first commissioned in 1977. The compressors, 4.5 K cold box, and control system design were modified to adapt the plant for the requirements of the CEBAF experimental halls. Additional subsystems of cryogen distribution, transfer lines, warm gas management, and computer control interface were added. This paper describes the major plant subsystems, modifications, operational experiences and performance

Supermarket Refrigeration System - Benchmark for Hybrid System Control

DEFF Research Database (Denmark)

Sloth, Lars Finn; Izadi-Zamanabadi, Roozbeh; Wisniewski, Rafal

2007-01-01

This paper presents a supermarket refrigeration system as a benchmark for development of new ideas and a comparison of methods for hybrid systems' modeling and control. The benchmark features switch dynamics and discrete valued input making it a hybrid system, furthermore the outputs are subjected...

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.

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.

Performance Characteristics of a Refrigerator-Freezer with Parallel Evaporators using a Linear Compressor

OpenAIRE

Min, Byungchae; Song, Sangjin; Noh, Kiyoul; Kim, Geonwoo; Yoon, Teaseung; Na, Sangkyung; Song, Sanghoon; Yang, Jangsik; Choi, Gyungmin; Kim, Duckjool

2016-01-01

A linear compressor for a domestic refrigerator-freezer has energy saving potential compared with a reciprocating compressor because of a low friction loss and free piston system. A linear compressor can control the piston stroke since it does not have mechanical restriction of piston movement. Therefore, the energy consumption of a domestic refrigerator-freezer using a linear compressor can be reduced by changing the cooling capacity of the compressor. In order to investigate the performance...

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.

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

Liquid over-feeding air conditioning system and method

Science.gov (United States)

Mei, V.C.; Chen, F.C.

1993-09-21

A refrigeration air conditioning system utilizing a liquid over-feeding operation is described. A liquid refrigerant accumulator-heat exchanger is placed in the system to provide a heat exchange relationship between hot liquid refrigerant discharged from condenser and a relatively cool mixture of liquid and vaporous refrigerant discharged from the evaporator. This heat exchange relationship substantially sub-cools the hot liquid refrigerant which undergoes little or no evaporation across the expansion device and provides a liquid over-feeding operation through the evaporator for effectively using 100 percent of evaporator for cooling purposes and for providing the aforementioned mixture of liquid and vaporous refrigerant. 1 figure.

Simulation of an adsorption solar cooling system

International Nuclear Information System (INIS)

Hassan, H.Z.; Mohamad, A.A.; Bennacer, R.

2011-01-01

A more realistic theoretical simulation model for a tubular solar adsorption refrigerating system using activated carbon-methanol (AC/M) pair has been introduced. The mathematical model represents the heat and mass transfer inside the adsorption bed, the condenser, and the evaporator. The simulation technique takes into account the variations of ambient temperature and solar radiation along the day. Furthermore, the local pressure, and local thermal conductivity variations in space and time inside the tubular reactor are investigated as well. A C++ computer program is written to solve the proposed numerical model using the finite difference method. The developed program covers the operations of all the system components along the cycle time. The performance of the tubular reactor, the condenser, and the evaporator has been discussed. Time allocation chart and switching operations for the solar refrigeration system processes are illustrated as well. The case studied has a 1 m 2 surface area solar flat plate collector integrated with a 20 stainless steel tubes containing the AC/M pair and each tube has a 5 cm outer diameter. In addition, the condenser pressure is set to 54.2 kpa. It has been found that, the solar coefficient of performance and the specific cooling power of the system are 0.211 and 2.326 respectively. In addition, the pressure distribution inside the adsorption bed has been found nearly uniform and varying only with time. Furthermore, the AC/M thermal conductivity is shown to be constant in both space and time.