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.

The absorption refrigerator as a thermal transformer

International Nuclear Information System (INIS)

Herrmann, F

2009-01-01

The absorption refrigerator can be considered a thermal transformer, that is, a device that is analogous to the electric transformer. The analogy is based on the correspondence between the extensive quantities, entropy and electric charge and the intensive variables, temperature and electric potential

The Absorption Refrigerator as a Thermal Transformer

Science.gov (United States)

Herrmann, F.

2009-01-01

The absorption refrigerator can be considered a thermal transformer, that is, a device that is analogous to the electric transformer. The analogy is based on the correspondence between the extensive quantities, entropy and electric charge and the intensive variables, temperature and electric potential. (Contains 1 footnote and 6 figures.)

Optimization of a solar driven absorption refrigerator in the transient regime

International Nuclear Information System (INIS)

Hamed, Mouna; Fellah, Ali; Ben Brahim, Ammar

2012-01-01

Highlights: ► Dynamic behavior of a solar absorption refrigerator endoreversible model. ► Using the principles of classical thermodynamics, mass and heat transfers. ► Minimizing heat exchange time to reach maximum performances. ► Major influence of the collector temperature on the model’s characteristics. ► Analogous effects of both the thermal load and the thermal conductance. -- Abstract: This contribution deals with the theoretical study in dynamic mode of an absorption refrigerator endoreversible model. The system is a cold generating station driven by solar energy. The main elements of the cycle are a refrigerated space, an absorption refrigerator and a solar collector form. A mathematical model is developed. It combines the classical thermodynamics and mass and heat transfers principles. The numerical simulation is made for different operating and conceptual conditions. A global minimizing time optimization is performed in view to reach maximum performances. Appropriate dimensionless groups are defined. The results are presented in normalized charts for general applications. The collector temperature presents major influence on the conceptual and functional characteristics compared to the stagnation temperature influence. On the other hand the thermal load in the refrigerated space and the thermal conductance of the walls has analogous effects, therefore important to be considered in actual design. As a result, the model is expected to be a useful tool for simulation, design, and optimization of solar collector based energy systems.

Absorption Refrigeration Cycles with Ammonia-Ionic Liquid Working Pairs Studied by Molecular Simulation.

Science.gov (United States)

Becker, Tim M; Wang, Meng; Kabra, Abhishek; Jamali, Seyed Hossein; Ramdin, Mahinder; Dubbeldam, David; Infante Ferreira, Carlos A; Vlugt, Thijs J H

2018-04-18

For absorption refrigeration, it has been shown that ionic liquids have the potential to replace conventional working pairs. Due to the huge number of possibilities, conducting lab experiments to find the optimal ionic liquid is infeasible. Here, we provide a proof-of-principle study of an alternative computational approach. The required thermodynamic properties, i.e., solubility, heat capacity, and heat of absorption, are determined via molecular simulations. These properties are used in a model of the absorption refrigeration cycle to estimate the circulation ratio and the coefficient of performance. We selected two ionic liquids as absorbents: [emim][Tf 2 N], and [emim][SCN]. As refrigerant NH 3 was chosen due to its favorable operating range. The results are compared to the traditional approach in which parameters of a thermodynamic model are fitted to reproduce experimental data. The work shows that simulations can be used to predict the required thermodynamic properties to estimate the performance of absorption refrigeration cycles. However, high-quality force fields are required to accurately predict the cycle performance.

Absorption Refrigeration Cycles with Ammonia–Ionic Liquid Working Pairs Studied by Molecular Simulation

Science.gov (United States)

2018-01-01

For absorption refrigeration, it has been shown that ionic liquids have the potential to replace conventional working pairs. Due to the huge number of possibilities, conducting lab experiments to find the optimal ionic liquid is infeasible. Here, we provide a proof-of-principle study of an alternative computational approach. The required thermodynamic properties, i.e., solubility, heat capacity, and heat of absorption, are determined via molecular simulations. These properties are used in a model of the absorption refrigeration cycle to estimate the circulation ratio and the coefficient of performance. We selected two ionic liquids as absorbents: [emim][Tf2N], and [emim][SCN]. As refrigerant NH3 was chosen due to its favorable operating range. The results are compared to the traditional approach in which parameters of a thermodynamic model are fitted to reproduce experimental data. The work shows that simulations can be used to predict the required thermodynamic properties to estimate the performance of absorption refrigeration cycles. However, high-quality force fields are required to accurately predict the cycle performance. PMID:29749996

Prediction of refrigerant absorption and onset of natural convection in lubricant oil

Energy Technology Data Exchange (ETDEWEB)

Barbosa, Jader R.; Marcelino Neto, Moises A. [Department of Mechanical Engineering, Federal University of Santa Catarina, Florianopolis, SC 88040900 (Brazil); Thoma, Stefan M. [Department of Mechanical and Process Engineering, Swiss Federal Institute of Technology, Sonneggstrasse 3, 8092 Zurich (Switzerland)

2008-11-15

Refrigerant absorption and mixing in lubricant oil are important in the design of refrigeration compressors and refrigeration systems. Experimental work is reported on absorption of R-134a vapour through the top interface of an initially stagnant layer of pure lubricant oil. Since the liquid refrigerant is heavier than the oil, mixing is enhanced due to natural mass convection. In the present paper, the behaviour of the liquid temperature during absorption is described based on measurements carried out in a test rig consisting of a transparent 70 mm ID, 150 mm long, vertical glass tube through which absorption can be directly observed. Transient liquid temperatures were measured at three different heights in the test section (two in the vapour, one in the liquid). The experimental work is complemented by a theoretical analysis of the critical time for the onset of mass transfer induced Rayleigh instability. The model is based on a critical mass transfer Rayleigh number criterion widely reported in the literature and takes into account the variation of physical properties in the liquid layer. The critical time for the onset of natural mass convection increases with decreasing system pressure as a result of a lower equilibrium concentration at the vapour-liquid interface. (author)

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

Parametric analysis for a new combined power and ejector-absorption refrigeration cycle

International Nuclear Information System (INIS)

Wang Jiangfeng; Dai Yiping; Zhang Taiyong; Ma Shaolin

2009-01-01

A new combined power and ejector-absorption refrigeration cycle is proposed, which combines the Rankine cycle and the ejector-absorption refrigeration cycle, and could produce both power output and refrigeration output simultaneously. This combined cycle, which originates from the cycle proposed by authors previously, introduces an ejector between the rectifier and the condenser, and provides a performance improvement without greatly increasing the complexity of the system. A parametric analysis is conducted to evaluate the effects of the key thermodynamic parameters on the cycle performance. It is shown that heat source temperature, condenser temperature, evaporator temperature, turbine inlet pressure, turbine inlet temperature, and basic solution ammonia concentration have significant effects on the net power output, refrigeration output and exergy efficiency of the combined cycle. It is evident that the ejector can improve the performance of the combined cycle proposed by authors previously.

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

International Nuclear Information System (INIS)

Qin Xiaoyong; Chen Lingen; Sun Fengrui; Wu Chih

2005-01-01

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

Industrial refrigeration by absorption/compression; Refrigeracion industrial por absorcion/compresion

Energy Technology Data Exchange (ETDEWEB)

Ayala Delgado, Ramon; Heard, Christopher Lionel [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

1996-12-31

The use of the absorption/compression refrigeration in the industrial area is analyzed. It is estimated than in Mexico 50% of the food is wasted for lack of refrigeration in the producing centers and by the inefficient distribution system, as well as for the hot climate. The functioning of the absorption refrigeration and the hybrid system absorption/compression which can operate with the two thermodynamic cycles in variable proportions, depending on the specific application, looking for operational advantages and energy efficiency is described. This type of technology could be applied in Mexico due to the lack of industrial refrigeration and to the need of substituting compressors in some companies which have up to 20 years of use [Espanol] Se analiza el uso de la refrigeracion por absorcion/compresion en el area industrial. En Mexico se estima que se desperdicia el 50% de los alimentos por falta de refrigeracion en los centros productores y por el deficiente sistema de distribucion, asi como por el clima calido. Se describe el funcionamiento de la refrigeracion por absorcion y la refrigeracion por absorcion/compresion o sistema hibrido, el cual puede funcionar con los dos tipos de ciclos termodinamicos, en proporciones variables, dependiendo de la aplicacion especifica, buscando ventajas de operacion y eficiencia energetica. Este tipo de tecnologia podria aplicarse en Mexico debido a la falta de refrigeracion industrial y a la necesidad de sustituir compresores en algunas empresas los cuales tienen hasta 20 anos de uso

Industrial refrigeration by absorption/compression; Refrigeracion industrial por absorcion/compresion

Energy Technology Data Exchange (ETDEWEB)

Ayala Delgado, Ramon; Heard, Christopher Lionel [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

1997-12-31

The use of the absorption/compression refrigeration in the industrial area is analyzed. It is estimated than in Mexico 50% of the food is wasted for lack of refrigeration in the producing centers and by the inefficient distribution system, as well as for the hot climate. The functioning of the absorption refrigeration and the hybrid system absorption/compression which can operate with the two thermodynamic cycles in variable proportions, depending on the specific application, looking for operational advantages and energy efficiency is described. This type of technology could be applied in Mexico due to the lack of industrial refrigeration and to the need of substituting compressors in some companies which have up to 20 years of use [Espanol] Se analiza el uso de la refrigeracion por absorcion/compresion en el area industrial. En Mexico se estima que se desperdicia el 50% de los alimentos por falta de refrigeracion en los centros productores y por el deficiente sistema de distribucion, asi como por el clima calido. Se describe el funcionamiento de la refrigeracion por absorcion y la refrigeracion por absorcion/compresion o sistema hibrido, el cual puede funcionar con los dos tipos de ciclos termodinamicos, en proporciones variables, dependiendo de la aplicacion especifica, buscando ventajas de operacion y eficiencia energetica. Este tipo de tecnologia podria aplicarse en Mexico debido a la falta de refrigeracion industrial y a la necesidad de sustituir compresores en algunas empresas los cuales tienen hasta 20 anos de uso

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.

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

Directory of Open Access Journals (Sweden)

O. Titlova

2016-12-01

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

Thermodynamic analysis of absorption refrigeration cycles using the second law of thermodynamics method

Energy Technology Data Exchange (ETDEWEB)

Aphornratana, S; Eames, I W [Sheffield Univ. (United Kingdom). Dept. of Mechanical and Process Engineering

1995-05-01

The paper provides an easy to follow description of the second law (of thermodynamics) method as applied to a single-effect absorption refrigerator cycle. Results are presented in a novel graphical format, which aids insight and understanding of those factors that most affect the performance of absorption refrigerators, and which in turn provides strong indicators for the direction of future research. A novel method of calculating the entropy of lithium bromide solutions is offered. (author)

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.

Compression-absorption (resorption) refrigerating machinery. Modeling of reactors; Machine frigorifique a compression-absorption (resorption). Modelisation des reacteurs

Energy Technology Data Exchange (ETDEWEB)

Lottin, O; Feidt, M; Benelmir, R [LEMTA-UHP Nancy-1, 54 - Vandoeuvre-les-Nancy (France)

1998-12-31

This paper is a series of transparencies presenting a comparative study of the thermal performances of different types of refrigerating machineries: di-thermal with vapor compression, tri-thermal with moto-compressor, with ejector, with free piston, adsorption-type, resorption-type, absorption-type, compression-absorption-type. A prototype of ammonia-water compression-absorption heat pump is presented and modeled. (J.S.)

Compression-absorption (resorption) refrigerating machinery. Modeling of reactors; Machine frigorifique a compression-absorption (resorption). Modelisation des reacteurs

Energy Technology Data Exchange (ETDEWEB)

Lottin, O.; Feidt, M.; Benelmir, R. [LEMTA-UHP Nancy-1, 54 - Vandoeuvre-les-Nancy (France)

1997-12-31

This paper is a series of transparencies presenting a comparative study of the thermal performances of different types of refrigerating machineries: di-thermal with vapor compression, tri-thermal with moto-compressor, with ejector, with free piston, adsorption-type, resorption-type, absorption-type, compression-absorption-type. A prototype of ammonia-water compression-absorption heat pump is presented and modeled. (J.S.)

Analysis of ammonia/water and ammonia/salt mixture absorption cycles for refrigeration purposes in fishing ships

International Nuclear Information System (INIS)

Táboas, Francisco; Bourouis, Mahmoud; Vallès, Manel

2014-01-01

In this work, the use of waste heat energy of jacket water in diesel engines of fishing ships was analysed for use as a heat source for absorption refrigeration systems. The thermodynamic simulation of an absorption refrigeration cycle with three different working fluid mixtures that use ammonia as a refrigerant was carried out. This analysis was assessed in terms of the cooling demand and cycle performance as a function of the evaporator, condenser and generator temperatures. Moreover, the need for rectifying the vapour stream leaving the generator was analysed together with the drag of the fraction of non-evaporated liquid to the absorber. The results show that the NH 3 /(LiNO 3  + H 2 O) and NH 3 /LiNO 3 fluid mixtures have higher values of COP as compared to NH 3 /H 2 O fluid mixture, the differences being more pronounced at low generation temperatures. If the activation temperature is set to 85 °C, the minimum evaporation temperatures that can be achieved are −18.8 °C for the cycle with NH 3 /LiNO 3 , −17.5 °C for the cycle with NH 3 /(LiNO 3  + H 2 O) cycle and −13.7 °C for the NH 3 /H 2 O cycle at a condensing temperature of 25 °C. Also, for the NH 3 /(LiNO 3  + H 2 O) fluid mixture, it has been demonstrated that the absorption refrigeration cycle can be operated without a distillation column and in this case the water content in the refrigerant stream entering the evaporator is less than 1.5% in weight at the operating conditions selected. - Highlights: •Ammonia absorption systems can provide refrigeration necessities for fishing ships. •Absorption refrigeration systems reduce the energy consumption of fishing ships. •The NH 3 /(LiNO 3  + H 2 O) mixture is recommended for absorption refrigeration cycles

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

Thermodynamic performance analysis of gas-fired air-cooled adiabatic absorption refrigeration systems

International Nuclear Information System (INIS)

Wang, L.; Chen, G.M.; Wang, Q.; Zhong, M.

2007-01-01

In China, the application of small size gas-fired air-cooled absorption refrigeration systems as an alternative for electric compression air conditioning systems has shown broad prospects due to occurrence of electricity peak demand in Chinese big cities and lack of water resources. However, for conventional air-cooled absorption refrigeration systems, it is difficult to enhance the heat and mass transfer process in the falling film absorber, and may cause problems, for example, remarkable increase of pressure, temperature and concentration in the generators, risk of crystallization, acceleration of corrosion, degradation of performance, and so on. This paper presents a gas-fired air-cooled adiabatic absorption refrigeration system using lithium bromide-water solutions as its working fluid, which is designed with a cooling capacity of 16 kW under standard conditions. The system has two new features of waste heat recovery of condensed water from generator and an adiabatic absorber with an air cooler. Performance simulation and characteristic analysis are crucial for the optimal control and reliability of operation in extremely hot climates. A methodology is presented to simulate thermodynamic performance of the system. The influences of outdoor air temperature on operation performances of the system are investigated

Materials and systems developments on solid absorption refrigeration with CaCl2·xNH3

International Nuclear Information System (INIS)

Iloeji, O.C.

1995-10-01

The paper presents some developments on the stabilization of CaCl 2 for use as a solid absorption material in refrigerators, the development of a refrigerator using the stabilized salt, and computer modelling of the refrigerator system. (author). 8 refs, 19 figs

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.

Experimental investigation and exergy analysis of a triple fluid vapor absorption refrigerator

International Nuclear Information System (INIS)

Jemaa, Radhouane Ben; Mansouri, Rami; Boukholda, Ismail; Bellagi, Ahmed

2016-01-01

Highlights: • Experimental study on a commercial triple fluid vapor absorption refrigerator performed. • An Aspen-hysys model developed and validated with experimental measurements. • Exergy analysis of the unit performed and discussed. • Absorber identified as largest source of irreversibility, followed by solution heat exchanger. - Abstract: This paper presents an energy and exergy analyses of a triple fluid vapor absorption refrigerator working with ammonia as refrigerant, water as absorbent and hydrogen as auxiliary gas. The experimental setup is constituted of a commercial unit equipped with the appropriate metrology. The temperature at the inlet and outlet of every component of the machine, as well as the cabinet and ambient temperature are continuously measured and monitored. A simulation model of the machine is developed using the process simulator Aspen-Hysys. The thermodynamic analysis includes energy and exergy efficiency calculations, destroyed exergy evaluation and degradation of the coefficient of performance (COP) in each component of the refrigerator. The results indicate that the absorber exhibits the largest source of irreversibility followed by the solution heat exchanger. These two components alone are at the origin of 63% of the total degradation of COP.

Simulation and experimental validation of the performance of a absorption refrigerator

International Nuclear Information System (INIS)

Olbricht, Michael; Luke, Andrea

2015-01-01

The two biggest obstacles to a stronger market penetration of absorption refrigerators are their high cost and the size of the apparatus, which are due to the inaccurate methods for plant design. In order to contribute to an improved design a thermodynamic model is presented to describe the performance of a absorption refrigerator with the working fluid water/lithium. In this model, the processes are displayed in the single apparatus and coupled to each other in the systemic context. Thereby the interactions between the apparatus can specifically investigated and thus the process limiting component can be identified under the respective conditions. A validation of the simulation model and the boundary conditions used is done based on experimental data operating a self-developed absorption refrigerator. In the simulation, the heat transfer surfaces in accordance with the real system can be specified. The heat transport is taken into account based on typical values for the heat transfer in the individual apparatuses. Simulation results show good agreement with the experimental data. The physical relationships and influences externally defined operating parameters are correctly reproduced. Due to the chosen low heat transfer coefficient, the calculated cooling capacities by the model are below the experimentally measured. Finally, the possibilities and limitations are discussed by using the model and further improvement possibilities are suggested. [de

Bio-mass stimulated absorption refrigerator for food storage in Papua New Guinea

Energy Technology Data Exchange (ETDEWEB)

Uppal, A.H.; Komuna, K.K. (University of Technology, Papua (New Guinea). Dept. of Mechanical Engineering)

1992-01-01

A medium capacity (140 litre) water-ammonia absorption refrigerator, thermally stimulated by a charcoal-stove is being developed to store food in remote locations and island communities of Papua New Guinea. The paper describes a prototype charcoal or biomass-stove thermal refrigerator in which the absorption cycle and thermo-syphonic cycle of a heating liquid has been coupled in a novel and straight forward approach. The system consisted of a heat-exchanger, in the form of a jacket surrounding the generator tube of a water-ammonia absorption cycle refrigerator, and was connected in a close-pipe work loop to a heat exchanger placed in a charcoal-stove. A heat-transfer oil flowed due to thermo-syphonic forces between the heat exchanger and the jacket. According to initial tests it took 4 hours for the system to warm up, and took another 7 hours for water in the freezer cabinet to approach 0{sup o}C from an initial 25{sup o}C. The cooling capacity of the evaporator was roughly 70% of the cooling capacity of the original system with electric heating. For a twelve hour test the stove consumed 2.5 kg of charcoal with an air port opening between 3 to 5 millimeters. Preliminary estimates indicate that the described prototype absorption unit stimulated by the wood/coconut husk stove (rather than electricity/kerosene), when manufactured commercially will cost less than US 1500 dollars at 1991 prices. (Author).

Cooling performance and energy saving of a compression-absorption refrigeration system driven by a gas engine

Energy Technology Data Exchange (ETDEWEB)

Sun, Z.G.; Guo, K.H. [Sun Yat-Sen University, Guangzhou (China). Engineering School

2006-07-01

The prototype of combined vapour compression-absorption refrigeration system was set up, where a gas engine drove directly an open screw compressor in a vapour compression refrigeration chiller and waste heat from the gas engine was used to operate absorption refrigeration cycle. The experimental procedure and results showed that the combined refrigeration system was feasible. The cooling capacity of the prototype reached about 589 kW at the Chinese rated conditions of air conditioning (the inlet and outlet temperatures of chilled water are 12 and 7{sup o}C, the inlet and outlet temperatures of cooling water are 30 and 35{sup o}C, respectively). Primary energy rate (PER) and comparative primary energy saving were used to evaluate energy utilization efficiency of the combined refrigeration system. The calculated results showed that the PER of the prototype was about 1.81 and the prototype saved more than 25% of primary energy compared to a conventional electrically driven vapour compression refrigeration unit. Error analysis showed that the total error of the combined cooling system measurement was about 4.2% in this work. (author)

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

Second law comparison of single effect and double effect vapour absorption refrigeration systems

International Nuclear Information System (INIS)

Gomri, Rabah

2009-01-01

In this paper a comparative study between single effect and double effect absorption refrigeration systems with identical cold output is carried out. Simulation results were used to study the influence of the various operating parameters on the performance coefficient, the thermal loads of the components, exergetic efficiency (rational efficiency) and the total change in exergy of the two systems. It is concluded that the COP of double effect system is approximately twice the COP of single effect system but the exergetic efficiency of double effect system increase slightly compared to the exergetic efficiency of single effect system. It is found that for each condenser and evaporator temperature, there is an optimum generator temperature where the total change in exergy of the single effect and double effect absorption refrigeration systems is minimum. At this point the COP and exergetic efficiency of the systems become maximum. In this study and when the evaporation temperature is varied from 4 deg. C to 10 deg. C, condenser and absorber temperatures are varied from 33 deg. C to 39 deg. C and generator (HPG) temperature is varied from 60 deg. C to 190 deg. C the maximum COP values of the single effect refrigeration systems are in the range of 0.73-0.79 and for double effect refrigeration systems are in the range of 1.22-1.42. The maximum exergetic efficiency values of the single effect refrigeration systems are in the range of 12.5-23.2% and for double effect refrigeration systems are in the range of 14.3-25.1%.

Thermodynamic simulation of ammonia-water absorption refrigeration system

Directory of Open Access Journals (Sweden)

Sathyabhama A.

2008-01-01

Full Text Available The ammonia-water absorption refrigeration system is attracting increasing research interests, since the system can be powered by waste thermal energy, thus reducing demand on electricity supply. The development of this technology demands reliable and effective system simulations. In this work, a thermodynamic simulation of the cycle is carried out to investigate the effects of different operating variables on the performance of the cycle. A computer program in C language is written for the performance analysis of the cycle.

Geothermal absorption refrigeration for food processing industries. Final report, December 13, 1976--November 13, 1977

Energy Technology Data Exchange (ETDEWEB)

Harris, R.L.; Olson, G.K.; Mah, C.S.; Bujalski, J.H.

1977-11-01

The first step in the economic analysis of the integration of geothermally powered absorption refrigeration into a food processing plant was an evaluation of the potential geothermal sites in the Western United States. The evaluation covered availability of raw materials, transportation, adequate geothermal source, labor, and other requirements for food processing plants. Several attractive geothermal sites were identified--Raft River, Idaho; Sespe Hot Springs, California; Vale Hot Springs, Oregon; Weisler-Crane Creek, Idaho; Cosco Hot Springs, California; and the Imperial Valley, California. The most economically attractive food processing industry was then matched to the site based on its particular energy, raw material, and transportation requirements. The more promising food processors identified were for frozen potato or vegetable products, freeze-dried products, and meat processing. For the refrigeration temperature range of +32/sup 0/F to -40/sup 0/F and geothermal temperature range of 212/sup 0/F to 300/sup 0/F, an absorption refrigeration system had to be identified, designed, and evaluated. Both the conventional ammonia/water and an organic absorption refrigeration system using monochlorodifluoromethane (R-22) as the refrigerant and dimethyl formamide (DMF) as the absorbent were studied. In general, only a 60/sup 0/F to 100/sup 0/F temperature drop would be effectively used for refrigeration leaving the remainder of the allowable temperature drop available for other use. The economic evaluation of the geothermal system installed in a food processing plant required the comparison of several principal alternatives. These alternatives were evaluated for three different food processing plants located at their optimum geothermal site: a forzen potato product processing plant located at Raft River, Idaho; a freeze-dried product plant located at Sespe Hot Springs, California; a beef slaughter operation located in the Imperial Valley of California. (JGB)

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

International Nuclear Information System (INIS)

Kaynakli, Omer; Saka, Kenan; Kaynakli, Faruk

2015-01-01

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

The Research on Programmable Control System of Lithium-Bromide Absorption Refrigerating Air Conditioner Based on the Network

Directory of Open Access Journals (Sweden)

Sun Lunan

2016-01-01

Full Text Available This article regard the solar lithium-bromide absorption refrigerating air conditioning system as the research object, and it was conducting adequate research of the working principle of lithium bromide absorption refrigerating machine, also it was analyzing the requirements of control system about solar energy air conditioning. Then the solar energy air conditioning control system was designed based on PLC, this system was given priority to field bus control system, and the remote monitoring is complementary, which was combining the network remote monitoring technology. So that it realized the automatic control and intelligent control of new lithium bromide absorption refrigerating air conditioning system with solar energy, also, it ensured the control system can automatically detect and adjust when the external conditions was random changing, to make air conditioning work effectively and steadily, ultimately ,it has great research significance to research the air conditioning control system with solar energy.

Modelling and simulation of an absorption cycle with a blow pump; Modellierung und Simulation eines Absorptionskreislaufes mit einer Blasenpumpe

Energy Technology Data Exchange (ETDEWEB)

Buecherl, Markus

2011-07-01

Diffusion-absorption refrigerators are commonly operated with ammonia and water. If a ionic liquid with negligible vapour pressure is substituted for water, the rectifier will be unnecessary. In the context of a diploma thesis, a diffusion-absorption refrigerator with a blower pump and ammonia and a ionic liquid as working fluid was modelled and simulated. For this, three models were selected from the relevant literature and compared. Changes in COP as a result of varied operating parameters were investigated as well. It was shown that it is possible, in principle, to operate a diffusion-absorption refrigerator with a ionic liquid. [German] Diffusions-Absorptions-Kaeltemaschinen werden in der Regel mit dem Arbeitsstoffpaar Ammoniak-Wasser betrieben. Ersetzt man das Absorptionsmittel Wasser gegen eine ionische Fluessigkeit, die nur einen vernachlaessigbaren Dampfdruck besitzt, kann man den Rektifikator einsparen. Im Rahmen einer Diplomarbeit wurde eine Diffusions-Absorptions-Kaeltemaschine mit einer Blasenpumpe und dem Arbeitsstoffpaar Ammoniak-Ionische Fluessigkeit modelliert und simuliert. Hierfuer wurden drei Modelle aus der Literatur ausgewaehlt. Diese Modelle wurden untereinander verglichen. Ausserdem wurde die Veraenderung des COP bei der Variation der Betriebsparameter fuer diese Berechnungsmodelle untersucht. Es konnte gezeigt werden, dass es prinzipiell moeglich ist, eine Diffusions-Absorptions-Kaeltemaschine mit ionischer Fluessigkeit zu betreiben.

Intermittent Solar Ammonia Absorption Cycle (ISAAC) refrigeration for lesser developed countries

Science.gov (United States)

Erickson, Donald C.

1990-02-01

The Intermittent Solar Ammonia Absorption Cycle (ISAAC) refrigerator is a solar thermal technology which provides low cost, efficient, reliable ice-making to areas without ready access to electricity. An ISAAC refrigeration system consists of a compound parabolic solar collector, two pressure vessels, a condenser, a cold box or refrigerated space, and simple connective piping -- no moving parts or electrical components. Most parts are simple construction or plumbing grade materials, locally available in many remote areas. This technology has numerous potential benefits in lesser developed countries both by providing a cheap, reliable source of ice, and, since manufacture requires only semi-skilled labor, a source of employment to the local economy. Applications include vaccine storage for health care clinics; fish, meat, and dairy product storage; and personal consumption. Importantly, this technology increases the quality of life for people in lesser developed countries without depleting fossil fuel resources or increasing the release of greenhouse gases such as CO2 and chlorofluorocarbons.

Quantum and classical dynamics of a three-mode absorption refrigerator

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Stefan Nimmrichter

2017-12-01

Full Text Available We study the quantum and classical evolution of a system of three harmonic modes interacting via a trilinear Hamiltonian. With the modes prepared in thermal states of different temperatures, this model describes the working principle of an absorption refrigerator that transfers energy from a cold to a hot environment at the expense of free energy provided by a high-temperature work reservoir. Inspired by a recent experimental realization with trapped ions, we elucidate key features of the coupling Hamiltonian that are relevant for the refrigerator performance. The coherent system dynamics exhibits rapid effective equilibration of the mode energies and correlations, as well as a transient enhancement of the cooling performance at short times. We find that these features can be fully reproduced in a classical framework.

The renewed absorption refrigerating engineering; Le groupe frigorifique a absorption, technique d`avenir?

Energy Technology Data Exchange (ETDEWEB)

Roumajon, J. [BETM (Country unknown/Code not available)

1998-04-01

This article reviews the characteristics of a refrigerating unit based on absorption. The main advantages are: silence, no vibration, security (no pressure, no inflammable and toxic gas), and a broad range of energy sources can be used (solar, geothermal, natural gas). The main disadvantages compared to a current compression cooling machine are: low yield, important volume of equipment, high cost and great amount of heat released. An installation based on a lithium bromide-water mixture is described, the role played by the different parts of the installation is explained. (A.C.)

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.

Comparative study of irreversibilities in an aqua-ammonia absorption refrigeration system

Energy Technology Data Exchange (ETDEWEB)

Ataer, O E [Gazi Univ., Ankara (TR). Mechanical Engineering Dept.; Gogus, Y [Middle East Technical Univ., Ankara (Turkey)

1991-03-01

Irreversibilities in components of an aqua-ammonia absorption refrigeration system (ARS) have been determined by second law analysis. The components of the ARS are as follows: condenser, evaporator, absorber, generator, pump, expansion valves, mixture heat exchanger and refrigerant heat exchanger. It is assumed that the ammonia concentration at the generator exit is, independent of the other parameters, equal to 0.999 and at the evaporator exit the gas is saturated vapour. Pressure losses between the generator and condenser, and the evaporator and absorber are taken into consideration. In the results the dimensionless exergy loss of each component, the exergetic coefficient of performance, the coefficient of performance and the circulation ratio are given graphically for each different generator, evaporator, condenser and absorber temperature. (author).

Application of vacuum membrane distillation to lithium bromide absorption refrigeration system

Energy Technology Data Exchange (ETDEWEB)

Wang, Zanshe; Feng, Shiyu; Li, Yun [School of Energy and Power Engineering, Xi' an Jiaotong University, Xi' an 710049 (China); Gu, Zhaolin [School of Human Settlement and Civil Engineering, Xi' an Jiaotong University, Xi' an 710049 (China)

2009-11-15

Conventional generator in lithium bromide absorption refrigeration system is too bulky and heavy to be fitted into small scale device, and the temperature of the driving heater in the generator seems much higher than low grade energy such as regenerative energy or waste heat energy. In this paper, desorption of aqueous lithium bromide solution by vacuum membrane distillation process was presented. Hollow fiber membrane module made by polyvinylidene fluoride was used as desorption device of aqueous lithium bromide solution. Influencing factors of feed flux, feed temperature in lumen side and vacuum pressure in shell side were tested and analyzed with orthogonal test. The results showed that permeation flux of water vapor increased with the feed temperature increasing and the feed flux increasing in lumen side, and the permeation flux also went up along with absolute pressure drop in shell side. Feasibility and potential application analysis shows that the temperature of the driving heat was low and the volume and weight of the desorption device was light. In this study, vacuum membrane distillation to the lithium bromide absorption refrigeration system has proved to be an efficient and cheap desorption mode. (author)

NLP model based thermoeconomic optimization of vapor compression–absorption cascaded refrigeration system

International Nuclear Information System (INIS)

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

2015-01-01

Highlights: • It addresses the size and cost estimation of cascaded refrigeration system. • Cascaded system is a promising decarburizing and energy efficient technology. • Second law analysis is carried out with modified Gouy-Stodola equation. • The total annual cost of plant operation is optimized in present work. - Abstract: This paper addresses the size and cost estimation of vapor compression–absorption cascaded refrigeration system (VCACRS) for water chilling application taking R410a and water–LiBr as refrigerants in compression and absorption section respectively which can help the design engineers in manufacturing and experimenting on such kind of systems. The main limitation in the practical implementation of VCACRS is its size and cost which are optimized in the present work by implementing Direct Search Method in non-linear programming (NLP) mathematical model of VCACRS. The main objective of optimization is to minimize the total annual cost of system which comprises of costs of exergy input and capital costs in monetary units. The appropriate set of decision variables (temperature of evaporator, condenser, generator, absorber, cascade condenser, degree of overlap and effectiveness of solution heat exchanger) minimizes the total annual cost of VCACRS by 11.9% with 22.4% reduction in investment cost at the base case whereas the same is reduced by 7.5% with 11.7% reduction in investment cost with reduced rate of interest and increased life span and period of operation. Optimization results show that the more investment cost in later case is well compensated through the performance and operational cost of the system. In the present analysis, optimum cascade condensing temperature is a strong function of period of operation and capital recovery factor. The cascading of compression and absorption systems becomes attractive for lower rate of interest and increase life span and operational period

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

Absorption Refrigeration Cycles with Ammonia-Ionic Liquid Working Pairs Studied by Molecular Simulation

NARCIS (Netherlands)

Becker, T.M.; Wang, M.; Kabra, Abhishek; Jamali, S.H.; Ramdin, M.; Dubbeldam, D.; Infante Ferreira, C.A.; Vlugt, T.J.H.

2018-01-01

For absorption refrigeration, it has been shown that ionic liquids have the potential to replace conventional working pairs. Due to the huge number of possibilities, conducting lab experiments to find the optimal ionic liquid is infeasible. Here, we provide a proof-of-principle study of an

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

International Nuclear Information System (INIS)

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

2013-01-01

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

Numerical Investigation of an Absorption-Diffusion Cooling Machine Using C3H8/C9H20 as Binary Working Fluid Étude numérique d’une machine frigorifique à absorption-diffusion utilisant le couple C3H8/C9H20

Directory of Open Access Journals (Sweden)

Dardour H.

2013-05-01

Full Text Available This paper is concerned with the analysis and the simulation of a heat-driven absorption-diffusion cooling machine which can operate with low-grade heat sources. The simplified configuration of the heat-powered absorption-diffusion refrigerating machine considered in this study is based on the Platen-Munters single pressure refrigerators principle [Platen B.C.V. and Munters C.G. (1928 Refrigerator, US Patent 1, 685-764J. Three working fluids are used, nonane as an absorbent, propane as a refrigerant and hydrogen as the inert auxiliary gas. The designed cooling capacity of the machine is 1 kW which is suitable for a domestic use for refrigeration purposes. We restricted the maximum temperature of the driving heat supplied to the generator to 130 °C, a temperature achievable with evacuated-tube solar collectors. The simulations are carried out using a commercially available flow sheeting software with the PengRobinson equation of state as property prediction method. In this paper, we analyze the heat and mass transfer characteristics in all relevant machine components (absorber, condenser, generator and solution heat exchangers. The simulations results allow determining the values of different parameters of the systems such as the refrigerant and the solvent temperatures in various points of the machine, the liquid and the vapor flow rates and compositions. The system performances were parametrically analyzed using the flow sheeting software. Performance characteristics were determined for a wide range of operating conditions allowing investigating and evaluating the effect of various design parameters. Ce papier est consacré à l’étude et l’analyse d’une machine frigorifique à absorption-diffusion. La machine est actionnée grâce à une source de chaleur de température modérée. La configuration et le principe de fonctionnement de l’appareil obéissent au modèle de Platen Munters [Platen B.C.V. and Munters C.G. (1928 Refrigerator

Evaluation of ionic liquids as absorbents for ammonia absorption refrigeration cycles using COSMO-based process simulations

Energy Technology Data Exchange (ETDEWEB)

Ruiz, E.; Ferro, V.R., E-mail: victor.ferro@uam.es; Riva, J. de; Moreno, D.; Palomar, J.

2014-06-01

Highlights: • NH{sub 3}–IL absorption cycles are modeled by COSMO-based Aspen simulations. • Proposed a priori computational approach is validated using experimental data. • Cycle performance was analyzed for conventional and task-specific ILs. • IL solvents with high NH{sub 3} absorption capacity improve the cycle performance. • Using IL mixtures is revealed as promising alternative in NH{sub 3} absorption applications. - Abstract: COSMO-based process simulations with Aspen Plus/Aspen HYSYS are used, for the first time, to a priori estimate the thermodynamic performance of ammonia absorption refrigeration cycles using ionic liquids as absorbents. This allows not only broadening the criteria set used to select/design ionic liquids with optimized properties to be used in that role, but also evaluating innovative strategies to improve the cycle’s performances. COSMO-RS method provides the information required for both creating the ionic liquid non-database components and specifying the COSMOSAC property model to perform Aspen Plus calculations. The computational procedure used here gives at the same time reasonable good property predictions of the vapor (refrigerant) and the condensed (ammonia + ionic liquid) phases as well as physically consistent estimations of the cycle’s performance under different conditions. Current results agree with those previously reported in the literature for several ionic liquid-based systems taken for comparison. In addition, task-specific ionic liquids, with improved properties for ammonia absorption, and also binary ionic liquid mixtures are considered in the analysis. It is obtained that ionic liquids showing higher ammonia absorption capacity among the considered absorbents simultaneously provide the best cycle’s performances. The cycle performances vary in relatively wide intervals depending on the ammonia concentration in the (refrigerant + absorbent) solutions. This behavior is strongly modulated by the ammonia

Evaluation of ionic liquids as absorbents for ammonia absorption refrigeration cycles using COSMO-based process simulations

International Nuclear Information System (INIS)

Ruiz, E.; Ferro, V.R.; Riva, J. de; Moreno, D.; Palomar, J.

2014-01-01

Highlights: • NH 3 –IL absorption cycles are modeled by COSMO-based Aspen simulations. • Proposed a priori computational approach is validated using experimental data. • Cycle performance was analyzed for conventional and task-specific ILs. • IL solvents with high NH 3 absorption capacity improve the cycle performance. • Using IL mixtures is revealed as promising alternative in NH 3 absorption applications. - Abstract: COSMO-based process simulations with Aspen Plus/Aspen HYSYS are used, for the first time, to a priori estimate the thermodynamic performance of ammonia absorption refrigeration cycles using ionic liquids as absorbents. This allows not only broadening the criteria set used to select/design ionic liquids with optimized properties to be used in that role, but also evaluating innovative strategies to improve the cycle’s performances. COSMO-RS method provides the information required for both creating the ionic liquid non-database components and specifying the COSMOSAC property model to perform Aspen Plus calculations. The computational procedure used here gives at the same time reasonable good property predictions of the vapor (refrigerant) and the condensed (ammonia + ionic liquid) phases as well as physically consistent estimations of the cycle’s performance under different conditions. Current results agree with those previously reported in the literature for several ionic liquid-based systems taken for comparison. In addition, task-specific ionic liquids, with improved properties for ammonia absorption, and also binary ionic liquid mixtures are considered in the analysis. It is obtained that ionic liquids showing higher ammonia absorption capacity among the considered absorbents simultaneously provide the best cycle’s performances. The cycle performances vary in relatively wide intervals depending on the ammonia concentration in the (refrigerant + absorbent) solutions. This behavior is strongly modulated by the ammonia absorption

Study of an ejector-absorption refrigeration cycle with an adaptable ejector nozzle for different working conditions

International Nuclear Information System (INIS)

Vereda, C.; Ventas, R.; Lecuona, A.; Venegas, M.

2012-01-01

Highlights: ► An absorption refrigeration cycle with an ejector device at the absorber inlet is presented. ► This cycle is able to reduce up to 9 °C the temperature of onset of refrigerant generation without extra energy consumption. ► At very low driving temperatures it allows increasing the cooling capacity. ► The ejector device proposed has a partially variable geometry and we study its influence on the cycle performances. -- Abstract: This paper presents a numerical model of an ejector-absorption (single-effect) refrigeration cycle with ammonia–lithium nitrate solution as working fluid, operating under steady-state conditions. In this cycle, the ejector is located at the absorber inlet replacing the solution expansion valve. The liquid–gas ejector entrains refrigerant vapor from the evaporator; this way the absorber pressure becomes higher than the evaporator pressure without any additional energy consumption. The objective of this numerical model is to evaluate the influence of the ejector geometry on the cycle performances and to determine the range of the heat source temperature in which it is convenient to use a practical ejector in the absorption cycle. The simulation is based on UA-ΔT lm models for separate heat transfer regions in a novel implementation using plate-type heat exchangers and this way the results are offered as a function of the external temperatures. This study focuses on evaluating the feasibility of an ejector whose nozzle area is adjustable while the rest of the ejector dimensions are fixed, thus being more feasible than complete variable geometry ejectors. The cycle performance is reported for different mixing tube constant diameters. Results of the simulation show that the use of an ejector allows, among others, to decrease the activation temperature approximately 9 °C in respect to the conventional single-effect absorption cycle and increasing the COP for moderate temperatures. The variable ejector nozzle geometry is

Theoretical study on the effect of operating conditions on performance of absorption refrigeration system

Energy Technology Data Exchange (ETDEWEB)

Kaynakli, Omer; Kilic, Muhsin [Uludag University, Faculty of Engineering and Architecture, Department of Mechanical Engineering, TR-16059, Bursa (Turkey)

2007-02-15

In this study, a detailed thermodynamic analysis of the water/lithium bromide absorption refrigeration cycle is performed. The influences of operating temperature and effectiveness of heat exchanger on the thermal loads of components, coefficients of performance (COP{sub c}, COP) and efficiency ratio ({eta}) are investigated. It is concluded that the COP{sub c} and COP values increase with increasing generator and evaporator temperatures but decrease with increasing condenser and absorber temperatures. The {eta} value varies with these temperatures. Also, the effects of solution and refrigerant heat exchangers on the performance, efficiency ratio of the system and fluid temperatures are compared. As a result, it is found that the solution heat exchanger (SHE) has more effect on the investigated parameters than the refrigerant heat exchanger (RHE). While the SHE increases the COP value up to a maximum 44%, the RHE has an effect of only 2.8%. (author)

Diffuse reflectance relations based on diffusion dipole theory for large absorption and reduced scattering.

Science.gov (United States)

Bremmer, Rolf H; van Gemert, Martin J C; Faber, Dirk J; van Leeuwen, Ton G; Aalders, Maurice C G

2013-08-01

Diffuse reflectance spectra are used to determine the optical properties of biological samples. In medicine and forensic science, the turbid objects under study often possess large absorption and/or scattering properties. However, data analysis is frequently based on the diffusion approximation to the radiative transfer equation, implying that it is limited to tissues where the reduced scattering coefficient dominates over the absorption coefficient. Nevertheless, up to absorption coefficients of 20  mm-1 at reduced scattering coefficients of 1 and 11.5  mm-1, we observed excellent agreement (r2=0.994) between reflectance measurements of phantoms and the diffuse reflectance equation proposed by Zonios et al. [Appl. Opt.38, 6628-6637 (1999)], derived as an approximation to one of the diffusion dipole equations of Farrell et al. [Med. Phys.19, 879-888 (1992)]. However, two parameters were fitted to all phantom experiments, including strongly absorbing samples, implying that the reflectance equation differs from diffusion theory. Yet, the exact diffusion dipole approximation at high reduced scattering and absorption also showed agreement with the phantom measurements. The mathematical structure of the diffuse reflectance relation used, derived by Zonios et al. [Appl. Opt.38, 6628-6637 (1999)], explains this observation. In conclusion, diffuse reflectance relations derived as an approximation to the diffusion dipole theory of Farrell et al. can analyze reflectance ratios accurately, even for much larger absorption than reduced scattering coefficients. This allows calibration of fiber-probe set-ups so that the object's diffuse reflectance can be related to its absorption even when large. These findings will greatly expand the application of diffuse reflection spectroscopy. In medicine, it may allow the use of blue/green wavelengths and measurements on whole blood, and in forensic science, it may allow inclusion of objects such as blood stains and cloth at crime

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

Absorption cycle commercial refrigerator using wood burning cook stove; Geladeira de absorcao acionada por fogao a lenha

Energy Technology Data Exchange (ETDEWEB)

Pereira, Jose Tomaz Vieira; Martins, Gilberto [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia Mecanica. Dept. de Energia

1991-12-31

The current utilization of wood burning cook stoves in Brazil and the socio-economical profile of their users were surveyed. A traditional heavy-mass wood-burning cook stove was studied as a thermal equipment. Simple changes in the geometry of the combustion chamber were suggested to improve the cooking efficiency. A closed two-phase thermosyphon using water as working fluid was designed, built and connected between the combustion chamber of the cook stove and a depressurized absorption refrigeration system to determine the heat flux and the temperature level. A commercial refrigerator unit, using the absorption cycle, was coupled with the wood stove through the thermosyphon. The overall results of the coupling point to successful country-side applications. (author) 12 refs., 9 figs., 4 tabs.

Optimization of operation of energy supply systems with co-generation and absorption refrigeration

Directory of Open Access Journals (Sweden)

Stojiljković Mirko M.

2012-01-01

Full Text Available Co-generation systems, together with absorption refrigeration and thermal storage, can result in substantial benefits from the economic, energy and environmental point of view. Optimization of operation of such systems is important as a component of the entire optimization process in pre-construction phases, but also for short-term energy production planning and system control. This paper proposes an approach for operational optimization of energy supply systems with small or medium scale co-generation, additional boilers and heat pumps, absorption and compression refrigeration, thermal energy storage and interconnection to the electric utility grid. In this case, the objective is to minimize annual costs related to the plant operation. The optimization problem is defined as mixed integer nonlinear and solved combining modern stochastic techniques: genetic algorithms and simulated annealing with linear programming using the object oriented “ESO-MS” software solution for simulation and optimization of energy supply systems, developed as a part of this research. This approach is applied to optimize a hypothetical plant that might be used to supply a real residential settlement in Niš, Serbia. Results are compared to the ones obtained after transforming the problem to mixed 0-1 linear and applying the branch and bound method.

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.

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

Energy Technology Data Exchange (ETDEWEB)

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

2007-07-01

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

Experimental study of refrigeration performance based on linear Fresnel solar thermal photovoltaic system

Science.gov (United States)

Song, Jinghui; Yuan, Hui; Xia, Yunfeng; Kan, Weimin; Deng, Xiaowen; Liu, Shi; Liang, Wanlong; Deng, Jianhua

2018-03-01

This paper introduces the working principle and system constitution of the linear Fresnel solar lithium bromide absorption refrigeration cycle, and elaborates several typical structures of absorption refrigeration cycle, including single-effect, two-stage cycle and double-effect lithium bromide absorption refrigeration cycle A 1.n effect absorption chiller system based on the best parameters was introduced and applied to a linear Fresnel solar absorption chiller system. Through the field refrigerator performance test, the results show: Based on this heat cycle design and processing 1.n lithium bromide absorption refrigeration power up to 35.2KW, It can meet the theoretical expectations and has good flexibility and reliability, provides guidance for the use of solar thermal energy.

Solar hybrid cooling system for high-tech offices in subtropical climate - Radiant cooling by absorption refrigeration and desiccant dehumidification

International Nuclear Information System (INIS)

Fong, K.F.; Chow, T.T.; Lee, C.K.; Lin, Z.; Chan, L.S.

2011-01-01

Highlights: → A solar hybrid cooling system is proposed for high-tech offices in subtropical climate. → An integration of radiant cooling, absorption refrigeration and desiccant dehumidification. → Year-round cooling and energy performances were evaluated through dynamic simulation. → Its annual primary energy consumption was lower than conventional system up to 36.5%. → The passive chilled beams were more energy-efficient than the active chilled beams. - Abstract: A solar hybrid cooling design is proposed for high cooling load demand in hot and humid climate. For the typical building cooling load, the system can handle the zone cooling load (mainly sensible) by radiant cooling with the chilled water from absorption refrigeration, while the ventilation load (largely latent) by desiccant dehumidification. This hybrid system utilizes solar energy for driving the absorption chiller and regenerating the desiccant wheel. Since a high chilled water temperature generated from the absorption chiller is not effective to handle the required latent load, desiccant dehumidification is therefore involved. It is an integration of radiant cooling, absorption refrigeration and desiccant dehumidification, which are powered up by solar energy. In this study, the application potential of the solar hybrid cooling system was evaluated for the high-tech offices in the subtropical climate through dynamic simulation. The high-tech offices are featured with relatively high internal sensible heat gains due to the intensive office electric equipment. The key performance indicators included the solar fraction and the primary energy consumption. Comparative study was also carried out for the solar hybrid cooling system using two common types of chilled ceilings, the passive chilled beams and active chilled beams. It was found that the solar hybrid cooling system was technically feasible for the applications of relatively higher cooling load demand. The annual primary energy

Energy analysis of a diffusion absorption cooling system using lithium nitrate, sodium thiocyanate and water as absorbent substances and ammonia as the refrigerant

International Nuclear Information System (INIS)

Acuña, A.; Velázquez, N.; Cerezo, J.

2013-01-01

A diffusion absorption cooling system is analyzed to determine the appropriate fluid for the unit, based on the coefficient of performance (COP) and operating conditions, by comparing lithium nitrate (LiNO 3 ), sodium thiocyanate (NaSCN) and water (H 2 O) as absorbent substances and by using ammonia (NH 3 ) as the refrigerant. The presence of crystallization in the system is analyzed as a function of the generator and absorber temperatures. Additionally, the effects on the efficiency of the system from adding the inert gas helium (He) or hydrogen (H 2 ) are studied. A mathematical model is developed and compared to experimental studies reported in the literature. At an evaporator temperature of −15 °C, a generator temperature of 120 °C and absorber and condenser temperatures of 40 °C, the results show that the best performance is achieved by the NH 3 –LiNO 3 –He mixture, with a COP of 0.48. This mixture performs 27–46% more efficient than the NH 3 –NaSCN mixture. The NH 3 –H 2 O mixture is 52–69% less efficient than the NH 3 –LiNO 3 mixture. However, when the evaporator runs at 7.5 °C, the NH 3 –H 2 O–He mixture achieves a more efficient COP than does the NH 3 –LiNO 3 –He mixture, and the NH 3 –NaSCN–He and NH 3 –LiNO 3 –He mixtures achieve the same COP when the evaporator is at 10 °C. At temperatures below 7.5 °C, the NH 3 –NaSCN–He mixture achieves a higher COP than does the NH 3 –H 2 O–He mixture. The NH 3 –LiNO 3 mixture shows crystallization at higher temperatures in the generator than does the NH 3 –NaSCN mixture. Moreover, at the same evaporator temperature, the NH 3 –LiNO 3 mixture works at activation temperatures lower than does the NH 3 –NaSCN mixture. -- Highlights: ► We studied a diffusion absorption cooling system with different working mixtures. ► The NH 3 –LiNO 3 mixture showed more efficiency than NH 3 –H 2 O mixture and NH 3 –NaSCN mixture. ► The generator and absorber temperature

Thermodynamic analysis of diesel engine coupled with ORC and absorption refrigeration cycle

International Nuclear Information System (INIS)

Salek, Farhad; Moghaddam, Alireza Naghavi; Naserian, Mohammad Mahdi

2017-01-01

Highlights: • Coupling ORC and Ammonia absorption cycles with diesel engine to recover energy. • By using designed bottoming system, recovered diesel engine energy is about 10%. • By using designed bottoming system, engine efficiency will grow about 4.65%. - Abstract: In this paper, Rankine cycle and Ammonia absorption cycle are coupled with Diesel engine to recover the energy of exhaust gases. The novelty of this paper is the use of ammonia absorption refrigeration cycle bottoming Rankine cycle which coupled with diesel engine to produce more power. Bottoming system converts engine exhaust thermal energy to cooling and mechanical energy. Energy transfer process has been done by two shell and tube heat exchangers. Simulation processes have been done by programming mathematic models of cycles in EES Program. Based on results, recovered energy varies with diesel engine load. For the particular load case of current research, the use of two heat exchangers causes 0.5% decrement of engine mechanical power. However, the recovered energy is about 10% of engine mechanical power.

Simulator for design absorption refrigeration system; Simulador para projeto de ciclos de refrigeracao por absorcao

Energy Technology Data Exchange (ETDEWEB)

Morejon, C.F.M.; Brum, N. de C. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia. Programa de Engenharia Mecanica]. E-mails: Camilo_freddy@hotmail.com; Nisio@serv.com.ufrj.br

2000-07-01

This work presents a development of a thermal fluid dynamics model and a solution of a steady state absorption refrigeration cycle, with ammonia water as the working fluid. Analytical thermodynamics models expressing the enthalpy in function of pressure, temperature and composition (h=f(P,T,x)), are used with the aim to design all of the cycle devices, moved by any type of energy such as solar, natural gas, steam or electrical energy (Morejon and Hackenberg, 1978). The development of the analysis is carried out by the application of thermal fluid dynamics concepts together with a detailed study of the heat and mass transfer in the different cycle stages. The thermodynamic cycle model, obtained from equation of state for ammonia - water mixtures (Ziegker and Trepp, 1984), is represented by the relation h - x (enthalpy-composition) for different pressures and temperatures. The obtained models are used to implement computational codes in MAPLE-V facilitating the design and simulation of refrigeration system. This study can be applied in the systems of air conditioning and refrigeration chambers design. (author)

Industrial refrigeration with high efficiency absorption; Refrigeracion industrial por absorcion de alta eficiencia

Energy Technology Data Exchange (ETDEWEB)

Ayala Delgado, R.; Heard, C. L. [Instituto de Investigaciones Electricas, Cuernavaca, (Mexico); Pardubicki, J. [LAJ International, Mexico D. F. (Mexico)

1995-12-31

The absorption refrigeration ammonia-lithium nitrate offers great advantages compared with the mechanical compression refrigeration with ammonia as well as with the absorption ammonia-water refrigeration. With heat temperatures of 1000 to 1400 Celsius degrees, for instance low pressure steam the generation of cold at low temperatures (-100 to -200 Celsius degrees) is possible. The system has less components and is much less expensive than the ammonia-water equipment with a price very similar to the ammonia mechanical compression equipment. The equipment consists of five main heat exchangers and a solution pump, resulting in a high reliability of its operation, requiring a minimum maintenance. The operation cost depends directly of the cost of the energy source. In case of using residual heat the operation cost is only the maintenance cost. Nowadays the cost of the electric energy is below the production cost, which can be a short term situation. In time terms of the comparable useful life time of an absorption refrigeration system (in excess of 20 years), it is reasonable to think that the operation costs will be less than the operation costs of an equipment with mechanical compression. To this day it is available a demonstration unit to exhibit the system in industrial plants with different energy sources. [Espanol] La refrigeracion por absorcion amoniaco/nitrato de litio ofrece grandes ventajas comparada tanto con la refrigeracion por compresion mecanica con amoniaco como con la refrigeracion por absorcion amoniaco/agua. Este sistema es mas eficiente y sencillo que el sistema de amoniaco/agua. Con calor de temperatura (100 a 140 grados centigrados por ejemplo vapor de baja presion, se permite la generacion de frio a temperaturas bajas (-10 a -20 grados centigrados). El sistema tiene menos componentes y es mucho mas barato que equipo de amoniaco/agua con un precio muy similar a sistemas por compresion mecanica de amoniaco. El sistema consiste en cinco

Industrial refrigeration with high efficiency absorption; Refrigeracion industrial por absorcion de alta eficiencia

Energy Technology Data Exchange (ETDEWEB)

Ayala Delgado, R; Heard, C L [Instituto de Investigaciones Electricas, Cuernavaca, (Mexico); Pardubicki, J [LAJ International, Mexico D. F. (Mexico)

1996-12-31

The absorption refrigeration ammonia-lithium nitrate offers great advantages compared with the mechanical compression refrigeration with ammonia as well as with the absorption ammonia-water refrigeration. With heat temperatures of 1000 to 1400 Celsius degrees, for instance low pressure steam the generation of cold at low temperatures (-100 to -200 Celsius degrees) is possible. The system has less components and is much less expensive than the ammonia-water equipment with a price very similar to the ammonia mechanical compression equipment. The equipment consists of five main heat exchangers and a solution pump, resulting in a high reliability of its operation, requiring a minimum maintenance. The operation cost depends directly of the cost of the energy source. In case of using residual heat the operation cost is only the maintenance cost. Nowadays the cost of the electric energy is below the production cost, which can be a short term situation. In time terms of the comparable useful life time of an absorption refrigeration system (in excess of 20 years), it is reasonable to think that the operation costs will be less than the operation costs of an equipment with mechanical compression. To this day it is available a demonstration unit to exhibit the system in industrial plants with different energy sources. [Espanol] La refrigeracion por absorcion amoniaco/nitrato de litio ofrece grandes ventajas comparada tanto con la refrigeracion por compresion mecanica con amoniaco como con la refrigeracion por absorcion amoniaco/agua. Este sistema es mas eficiente y sencillo que el sistema de amoniaco/agua. Con calor de temperatura (100 a 140 grados centigrados por ejemplo vapor de baja presion, se permite la generacion de frio a temperaturas bajas (-10 a -20 grados centigrados). El sistema tiene menos componentes y es mucho mas barato que equipo de amoniaco/agua con un precio muy similar a sistemas por compresion mecanica de amoniaco. El sistema consiste en cinco

Solution procedure and performance evaluation for a water–LiBr absorption refrigeration machine

International Nuclear Information System (INIS)

Wonchala, Jason; Hazledine, Maxwell; Goni Boulama, Kiari

2014-01-01

The water–lithium bromide absorption cooling machine was investigated theoretically in this paper. A detailed solution procedure was proposed and validated. A parametric study was conducted over the entire admissible ranges of the desorber, condenser, absorber and evaporator temperatures. The performance of the machine was evaluated based on the circulation ratio which is a measure of the system size and cost, the first law coefficient of performance and the second law exergy efficiency. The circulation ratio and the coefficient of performance were seen to improve as the temperature of the heat source increased, while the second law performance deteriorated. The same qualitative responses were obtained when the temperature of the refrigerated environment was increased. On the other hand, simultaneously raising the condenser and absorber temperatures was seen to result in a severe deterioration of both the circulation ratio and first law coefficient of performance, while the second law performance indicator improved significantly. The influence of the difference between the condenser and absorber exit temperatures, as well as that of the internal recovery heat exchanger on the different performance indicators was also calculated and discussed. - Highlights: • Analysis of a water–LiBr absorption machine, including detailed solution procedure. • Performance assessed using first and second law considerations, as well as flow ratio. • Effects of heat source and refrigerated environment temperatures on the performance. • Effects of the difference between condenser and absorber temperatures. • Effects of internal heat exchanger efficiency on overall cooling machine performance

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.

ARTI refrigerant database

Energy Technology Data Exchange (ETDEWEB)

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

1996-04-15

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

Simulation of an air conditioning absorption refrigeration system in a co-generation process combining a proton exchange membrane fuel cell

Energy Technology Data Exchange (ETDEWEB)

Pilatowsky, I.; Gamboa, S.A.; Rivera, W. [Centro de Investigacion en Energia - UNAM, Temixco, Morelos (Mexico); Romero, R.J. [Centro de Investigacion en Ingenieria y Ciencias Aplicadas - UAEM, Cuernavaca, Morelos (Mexico); Isaza, C.A. [Universidad Pontificia Bolivariana, Medellin (Colombia). Instituto de Energia y Termodinamica; Sebastian, P.J. [Centro de Investigacion en Energia - UNAM, Temixco, Morelos (Mexico); Cuerpo Academico de Energia y Sustentabilidad-UP Chiapas, Tuxtla Gutierrez, Chiapas (Mexico); Moreira, J. [Cuerpo Academico de Energia y Sustentabilidad-UP Chiapas, Tuxtla Gutierrez, Chiapas (Mexico)

2007-10-15

In this work, a computer simulation program was developed to determine the optimum operating conditions of an air conditioning system during the co-generation process. A 1 kW PEMFC was considered in this study with a chemical/electrical theoretical efficiency of 40% and a thermal efficiency of 30% applying an electrical load of 100%. A refrigeration-absorption cycle (RAC) operating with monomethylamine-water solutions (MMA-WS), with low vapor generation temperatures (up to 80 C) is proposed in this work. The computer simulation was based on the refrigeration production capacity at the maximum power capacity of the PEMFC. Heat losses between the fuel cell and the absorption air conditioning system at standard operating conditions were considered to be negligible. The results showed the feasibility of using PEMFC for cooling, increasing the total efficiency of the fuel cell system. (author)

Refrigeration and global warming

International Nuclear Information System (INIS)

Anon.

1997-01-01

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

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

International Nuclear Information System (INIS)

Zheng Danxing; Meng Xuelin

2012-01-01

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

Second law-based thermodynamic analysis of water-lithium bromide absorption refrigeration system

Energy Technology Data Exchange (ETDEWEB)

Kilic, Muhsin [Department of Mechanical Engineering, Faculty of Engineering and Architecture, Uludag University, TR 16059, Bursa (Turkey)]. E-mail: mkilic@uludag.edu.tr; Kaynakli, Omer [Department of Mechanical Engineering, Faculty of Engineering and Architecture, Uludag University, TR 16059, Bursa (Turkey)

2007-08-15

In this study, the first and the second law of thermodynamics are used to analyze the performance of a single-stage water-lithium bromide absorption refrigeration system (ARS) when some working parameters are varied. A mathematical model based on the exergy method is introduced to evaluate the system performance, exergy loss of each component and total exergy loss of all the system components. Parameters connected with performance of the cycle-circulation ratio (CR), coefficient of performance (COP), Carnot coefficient of performance (COP{sub c} ), exergetic efficiency ({xi}) and efficiency ratio ({tau})-are calculated from the thermodynamic properties of the working fluids at various operating conditions. Using the developed model, the effect of main system temperatures on the performance parameters of the system, irreversibilities in the thermal process and non-dimensional exergy loss of each component are analyzed in detail. The results show that the performance of the ARS increases with increasing generator and evaporator temperatures, but decreases with increasing condenser and absorber temperatures. Exergy losses in the expansion valves, pump and heat exchangers, especially refrigerant heat exchanger, are small compared to other components. The highest exergy loss occurs in the generator regardless of operating conditions, which therefore makes the generator the most important component of the cycle.

Second law-based thermodynamic analysis of water-lithium bromide absorption refrigeration system

International Nuclear Information System (INIS)

Kilic, Muhsin; Kaynakli, Omer

2007-01-01

In this study, the first and the second law of thermodynamics are used to analyze the performance of a single-stage water-lithium bromide absorption refrigeration system (ARS) when some working parameters are varied. A mathematical model based on the exergy method is introduced to evaluate the system performance, exergy loss of each component and total exergy loss of all the system components. Parameters connected with performance of the cycle-circulation ratio (CR), coefficient of performance (COP), Carnot coefficient of performance (COP c ), exergetic efficiency (ξ) and efficiency ratio (τ)-are calculated from the thermodynamic properties of the working fluids at various operating conditions. Using the developed model, the effect of main system temperatures on the performance parameters of the system, irreversibilities in the thermal process and non-dimensional exergy loss of each component are analyzed in detail. The results show that the performance of the ARS increases with increasing generator and evaporator temperatures, but decreases with increasing condenser and absorber temperatures. Exergy losses in the expansion valves, pump and heat exchangers, especially refrigerant heat exchanger, are small compared to other components. The highest exergy loss occurs in the generator regardless of operating conditions, which therefore makes the generator the most important component of the cycle

Parametric study of an absorption refrigeration machine using advanced exergy analysis

International Nuclear Information System (INIS)

Gong, Sunyoung; Goni Boulama, Kiari

2014-01-01

An advanced exergy analysis of a water–lithium bromide absorption refrigeration machine was conducted. For each component of the machine, the proposed analysis quantified the irreversibility that can be avoided and the irreversibility that is unavoidable. It also identified the irreversibility originating from inefficiencies within the component and the irreversibility that does not originate from the operation of the considered component. It was observed that the desorber and absorber concentrated most of the exergy destruction. Furthermore, the exergy destruction at these components was found to be dominantly endogenous and unavoidable. A parametrical study has been presented discussing the sensitivity of the different performance indicators to the temperature at which the heat source is available, the temperature of the refrigerated environment, and the temperature of the cooling medium used at the condenser and absorber. It was observed that the endogenous avoidable exergy destruction at the desorber, i.e. the portion of the desorber irreversibility that could be avoided by improving the design and operation of the desorber, decreased when the heat source or the temperature at which the cooling effect was generated increased, and it decreased when the heat sink temperature increased. The endogenous avoidable exergy destruction at the absorber displayed the same variations, though it was observed to be less affected by the heat source temperature. Contrary to the aforementioned two components, the exergy destruction at the evaporator and condenser were dominantly endogenous and avoidable, with little sensitivity to the cycle operating parameters. - Highlights: • Endogenous, exogenous, avoidable and unavoidable irreversibilities were calculated for a water–LiBr absorption machine. • Overall, desorber and absorber concentrated most of the exergy destruction of the cycle. • The exergy destruction was mainly endogenous and unavoidable for the desorber and

Diffuse reflectance relations based on diffusion dipole theory for large absorption and reduced scattering

NARCIS (Netherlands)

Bremmer, Rolf H.; van Gemert, Martin J. C.; Faber, Dirk J.; van Leeuwen, Ton G.; Aalders, Maurice C. G.

2013-01-01

Diffuse reflectance spectra are used to determine the optical properties of biological samples. In medicine and forensic science, the turbid objects under study often possess large absorption and/or scattering properties. However, data analysis is frequently based on the diffusion approximation to

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2001-10-01

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

A solar absorption refrigeration system operating with the mixture ammonia-lithium nitrate

Energy Technology Data Exchange (ETDEWEB)

Rivera, W.; Martinez, F.; Garcia-Valladares, O. [Centro de Investigacion en Energia de la Univ. Nacional Autonoma de Mexico, Mor (Mexico); Rivera, C.O. [Univ. Veracruzana, Campus Coatzacoalcos (Mexico)

2007-07-01

An intermittent solar absorption refrigeration system for ice production operating with the ammonia-lithium nitrate mixture has been developed in the Centro de Investigacion en Energia of the Universidad Nacional Autonoma de Mexico. The system consists basically of a compound parabolic concentrator (CPC), a generator-absorber, a condenser, a condensate tank, an expansion valve and an evaporator. The system was evaluated in sunny days with insolations above 20 MJ/m{sup 2}-day at different condenser temperatures. The generator temperatures varied from 108 to 121 C and the evaporator temperatures inside the camera from -8 to 0 C. The coefficients of performance (COP) varied from 0.13 to 0.26 depending of the operating temperatures of the system and the solar irradiation. (orig.)

Edge-promoting reconstruction of absorption and diffusivity in optical tomography

International Nuclear Information System (INIS)

Hannukainen, A; Hyvönen, N; Majander, H; Harhanen, L

2016-01-01

In optical tomography a physical body is illuminated with near-infrared light and the resulting outward photon flux is measured at the object boundary. The goal is to reconstruct internal optical properties of the body, such as absorption and diffusivity. In this work, it is assumed that the imaged object is composed of an approximately homogeneous background with clearly distinguishable embedded inhomogeneities. An algorithm for finding the maximum a posteriori estimate for the absorption and diffusion coefficients is introduced assuming an edge-preferring prior and an additive Gaussian measurement noise model. The method is based on iteratively combining a lagged diffusivity step and a linearization of the measurement model of diffuse optical tomography with priorconditioned LSQR. The performance of the reconstruction technique is tested via three-dimensional numerical experiments with simulated data. (paper)

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.

Optical measurements of absorption changes in two-layered diffusive media

International Nuclear Information System (INIS)

Fabbri, Francesco; Sassaroli, Angelo; Henry, Michael E; Fantini, Sergio

2004-01-01

We have used Monte Carlo simulations for a two-layered diffusive medium to investigate the effect of a superficial layer on the measurement of absorption variations from optical diffuse reflectance data processed by using: (a) a multidistance, frequency-domain method based on diffusion theory for a semi-infinite homogeneous medium; (b) a differential-pathlength-factor method based on a modified Lambert-Beer law for a homogeneous medium and (c) a two-distance, partial-pathlength method based on a modified Lambert-Beer law for a two-layered medium. Methods (a) and (b) lead to a single value for the absorption variation, whereas method (c) yields absorption variations for each layer. In the simulations, the optical coefficients of the medium were representative of those of biological tissue in the near-infrared. The thickness of the first layer was in the range 0.3-1.4 cm, and the source-detector distances were in the range 1-5 cm, which is typical of near-infrared diffuse reflectance measurements in tissue. The simulations have shown that (1) method (a) is mostly sensitive to absorption changes in the underlying layer, provided that the thickness of the superficial layer is ∼0.6 cm or less; (2) method (b) is significantly affected by absorption changes in the superficial layer and (3) method (c) yields the absorption changes for both layers with a relatively good accuracy of ∼4% for the superficial layer and ∼10% for the underlying layer (provided that the absorption changes are less than 20-30% of the baseline value). We have applied all three methods of data analysis to near-infrared data collected on the forehead of a human subject during electroconvulsive therapy. Our results suggest that the multidistance method (a) and the two-distance partial-pathlength method (c) may better decouple the contributions to the optical signals that originate in deeper tissue (brain) from those that originate in more superficial tissue layers

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2011-12-15

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

Design and simulation of a heat transformer of a directly solar-driven diffusion absorption chiller; Auslegung und Simulation von Waermeuebertragern einer direkt solarthermisch angetriebenen Diffusions-Absorptionskaeltemaschine

Energy Technology Data Exchange (ETDEWEB)

Hong, Josua; Schmid, Fabian; Spindler, Klaus [Stuttgart Univ. (DE). Inst. fuer Thermodynamik und Waermetechnik (ITW)

2011-07-01

The ITW is working on a directly solar-driven diffusion absorption chiller. Solar cooling offers vast potential for saving fossil resources, e.g. owing to the good temporal agreement between insolation and cold demand for cooling of office buildings and domestic buildings. So far, the focus has been on central systems with indirect solar thermal operation. Direct solar thermal plants can be decentral. A diffusion-absorption refrigeration system without mechanical components was constructed. Solvent circulation is achieved by the thermosyphon principle, which makes the plant noiseless, wear-free, and low-maintenance. In the course of a study, a mathematical model of the heat exchangers was established on the basis of the heat transfer equations, and optimisation suggestions for the heat exchanger were identified on this basis. The influence of the pressure gradient - which is decisive -, and the influence of geometry and materials were investigated. The simulations were validated by measurements. Concrete optimisation potentials were identified, and first suggestions were implemented. [German] Am ITW wird intensiv an einer direkt solarthermisch angetriebenen Diffusions-Absorptionskaeltemaschine (DAKM) geforscht. Die solare Kuehlung bietet grosse Potentiale zur Einsparung fossiler Energietraeger. Ein Grund dafuer ist die gute zeitliche Uebereinstimmung zwischen Solarstrahlung und dem Kaeltebedarf fuer die Kuehlung von Wohngebaeuden und Bueros. Bislang standen zentrale und indirekt solarthermisch angetriebene Systeme zur Kaelteerzeugung im Fokus. Die direkt solarthermisch angetriebene Anlage kann auf Grund ihres neuen Konzepts dezentral aufgebaut und betrieben werden. Auf Grundlage des Diffusions-Absorptionskaelteprozesses wurde eine Anlage gebaut, die ohne mechanische Bauteile funktioniert. Der Loesungsmittelumlauf erfolgt durch das Thermosiphonprinzip. Dadurch ist die Anlage im Betrieb geraeuschlos, verschleissfrei und wartungsarm. Im Rahmen einer Studienarbeit

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.

Analysis of Refrigeration Cycle Performance with an Ejector

Directory of Open Access Journals (Sweden)

Wani J. R.

2016-01-01

Full Text Available A conventional refrigeration cycle uses expansion device between the condenser and the evaporator which has losses during the expansion process. A refrigeration cycle with ejector is a promising modification to improve the performance of conventional refrigeration cycle. The ejector is used to recover some of the available work so that the compressor suction pressure increases. To investigate the enhancement a model with R134a refrigerant was developed. To solve the set of equations and simulate the cycle performance a subroutine was written on engineering equation solver (EES environment. At specific conditions, the refrigerant properties are obtained from EES. At the design conditions the ejector refrigeration cycle achieved 5.141 COP compared to 4.609 COP of the conventional refrigeration cycle. This means that ejector refrigeration cycle offers better COP with 10.35% improvement compared to conventional refrigeration cycle. Parametric analysis of ejector refrigeration cycle indicated that COP was influenced significantly by evaporator and condenser temperatures, entrainment ratio and diffuser efficiency.

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.

Conception and simulation of an improved solar refrigeration unit

International Nuclear Information System (INIS)

Chaouachi, B.; Gabsi, S.

2006-01-01

If the solar energy possesses the advantage to be c lean , free and new able, this last is probably, considered like an adapted potential solution, that answers in even time at a economic preoccupation and ecological problems. Among the main done currently research is the use of free source to make operate system of refrigeration. following a bibliographic study on the absorption cycles, the utilized couples absorbents-refrigerating fluids and the capture of the solar energy, an unit refrigeration using an improved solar absorption cycle of ammonia has been conceived and studied. The simulation results in permanent regime concerned the determination of the variation of the performance criteria mainly according to the operatives kept for this study. The obtained results showed, that the improved mono pressure absorption cycle of ammonia is suitable well for the cold production by means of the solar energy and that with a simple plate collector we can reach a power, of the order of 900 watts sufficient for domestic use.(Author)

A thermodynamic evaluation on high pressure condenser of double effect absorption refrigeration system

International Nuclear Information System (INIS)

Yılmaz, İbrahim Halil; Saka, Kenan; Kaynakli, Omer

2016-01-01

One of the parameters affecting the COP of the absorption system can be considered as the thermal balance between the high pressure condenser (HPC) and the low pressure generator (LPG) since heat rejected from the HPC is utilized as an energy source by the LPG. Condensation of the water vapor in the HPC depends on the heat removal via the LPG. This circumstance is significant for making an appropriate design and a controllable system with high performance in practical applications. For this reason, a thermodynamic analysis for the HPC of a double effect series flow water/lithium bromide absorption refrigeration system was emphasized in this study. A simulation was developed to investigate the energy transfer between the HPC and LPG. The results show that the proper designation of the HPC temperature improves the COP and ECOP due its significant impact, and its value necessarily has to be higher than the outlet temperature of the LPG based on the operating scheme. Furthermore, the COP and ECOP of the absorption system can be raised in the range of 9.72–35.09% in case of 2 °C-temperature increment in the HPC under the described conditions to be applied. - Highlights: • Thermal balance in HPC/LPG unit of a double effect absorption system was studied. • A simulation program was developed and its outputs were validated. • A parametric study was conducted for a wide range of component temperatures. • Proper designation of the HPC temperature improves the COP and ECOP. • The system performance raised 9.72–35.09% by controlling the HPC temperature.

Proposal and analysis of a high-efficiency combined desalination and refrigeration system based on the LiBr-H2O absorption cycle-Part 1: System configuration and mathematical model

International Nuclear Information System (INIS)

Wang Yongqing; Lior, Noam

2011-01-01

Simultaneous production of fresh water and refrigeration are often required, e.g. in warm-climate water-deficient regions, and this study is a proposal and analysis of an efficient way of producing both of them by consuming mainly low-grade heat. After introducing the configuration choice methodology, a combined refrigeration and water system, ARHP-MEE (absorption refrigeration heat pump and multi-effect evaporation desalter), which is the integration of a LiBr-H 2 O refrigeration unit, a LiBr-H 2 O heat pump, and a low-temperature multi-effect evaporation desalination unit, is proposed, and the mathematical model is presented and validated. The model serves for conducting a performance analysis of the combined system, reported in Part 2 of this two-part paper.

Synthesis of integrated absorption refrigeration systems involving economic and environmental objectives and quantifying social benefits

International Nuclear Information System (INIS)

Lira-Barragán, Luis Fernando; Ponce-Ortega, José María; Serna-González, Medardo; El-Halwagi, Mahmoud M.

2013-01-01

This paper presents a new methodology for energy integration of systems that require absorption refrigeration. It allows heat exchange among process hot and cold streams and the integration of excess process heat as well as external utilities provided by solar energy, fossil fuels and biofuels. An optimization formulation is developed to address the multiple objectives of simultaneously minimizing the total annualized cost and the greenhouse gas emissions while the social impact is measured by the number of jobs generated by the project in the entire life cycle. The economic function accounts for the tax credit obtained by the reduction of greenhouse gas emissions when cleaner technologies are used. The proposed model also considers the optimal selection of different types of solar collectors and the optimal time-based usage of solar energy, fossil fuel, and biofuel. Two example problems are presented to show the applicability of the proposed methodology. -- Highlights: ► An approach for the thermal integration of refrigeration processes is proposed. ► Different forms of sustainable energies are considered in the optimization process. ► Economic and environmental objectives are considered quantifying the number of jobs. ► The availability for the different forms of energy is taken into account. ► Results show significant advantages obtained with the proposed approach

Closed Cycle Solar Refrigeration with the Calcium Chloride System ...

African Journals Online (AJOL)

A closed cycle solid absorption intermittent refrigerator, using CaC12 absorbent and NH3 refrigerant, was constructed and tested to obtain the instantaneous and cumulative available overall COP. The combined collector/absorber/generator unit had double glazing of 1.14 m2 exposed areas. The system was fitted with a ...

Refrigeration plants using carbon dioxide as refrigerant: measuring and modelling the solubility and diffusion of carbon dioxide in polymers used as sealing materials

DEFF Research Database (Denmark)

von Solms, Nicolas; Kristensen, Jakob

2010-01-01

Because of increased environmental pressure, there is currently a movement away from more traditional refrigerants such as HCFC's toward refrigerants with lower global warming potential such as carbon dioxide (CO2). However, the use of CO2 as a refrigerant requires a refrigeration cycle...

Experimental investigation on an ammonia-water-lithium bromide absorption refrigeration system without solution pump

International Nuclear Information System (INIS)

Wu Tiehui; Wu Yuyuan; Yu Zhiqiang; Zhao Haichen; Wu Honglin

2011-01-01

Highlights: → An absorption refrigeration system with ternary solution of NH 3 -H 2 O-LiBr was set up. → Performance of the NH 3 -H 2 O-LiBr system without solution pump was firstly tested. → Generator pressure in NH 3 -H 2 O-LiBr system was lower than the one in NH 3 -H 2 O system. → The COP of the NH 3 -H 2 O-LiBr system was 51.89% larger than the NH 3 -H 2 O binary system. → The optimum mass fraction of LiBr of about 23% led to the largest COP of 0.401. -- Abstract: Experimental researches were carried out on a novel ammonia-water-lithium bromide ternary solution absorption refrigeration and air-conditioning system without solution pump and distillation equipments. The experiments were conducted by using three kinds of NH 3 -H 2 O binary solution and 17 kinds of ternary solution with difference in mass fraction of NH 3 and LiBr. The experimental results showed that the vapor pressure of the generator in the system would be lower than that of the generator in an ammonia-water absorption system. In above two situations the same ammonia mass fraction and the same solution temperature were kept. The amplitude of vapor pressure decrease of the system generator would be larger with the increase of the mass fraction of LiBr. The maximum amplitude of decrease would be of 50%. With the increase of the mass fraction of LiBr, the coefficient of performance (COP) of the system would be increased initially, and then decreased later when the mass fraction of LiBr exceeded a certain value. This value was about 23% for the solution with ammonia mass fraction of 50% and 55%, and about 30% for the solution with ammonia mass fraction of 60%. Compared with the ammonia-water system, the COP of the ternary solution system with the same mass fraction of ammonia would increase up to 30%. With the ammonia mass fraction of 60% and LiBr mass fraction of 30% applied, the COP of the ternary solution system was increased up to 0.401. It was 51.89% higher than that when binary

Exergy analysis of a combined vapor power cycle and boiler flue gas driven double effect water–LiBr absorption refrigeration system

International Nuclear Information System (INIS)

Talukdar, K.; Gogoi, T.K.

2016-01-01

Highlights: • A combined vapor power and double effect water–LiBr absorption refrigeration system is proposed. • The flue gas of the power cycle boiler is the heat source for the double effect refrigeration system. • Energy and exergy analyses are performed to evaluate performance of the combined system. • Effect of high pressure generator temperature on combined system performance is highlighted. • Comparison is provided with a single effect absorption system integrated combined system. - Abstract: A combined vapor power cycle (PC) and double effect water–LiBr absorption refrigeration system (ARS) is proposed in this study. The boiler leaving flue gas of the PC is the heat source for the high pressure generator (HPG) of the double effect ARS. Exergy analysis of the proposed system is performed to show the performance variation of both the topping PC and the bottoming ARS with changing HPG temperature from 120 °C to 150 °C. Further the performance of double effect ARS integrated combined power and cooling system is compared with a similar system integrated with a single effect ARS. HPG temperature of the double effect ARS and generator temperature of the single effect ARS are considered as 120 °C and 80 °C respectively. Results show that the power and efficiency of the topping PC decreases with HPG temperature due to reduction in steam generation rate in the boiler. COP and exergy efficiency of the double effect ARS also reduces with increasing HPG temperature. The irreversible losses in the PC components decrease while the total irreversibility of the combined power and cooling system increases with HPG temperature due to increase in exergy loss with the HPG leaving flue gas and irreversibility of the ARS components. PC performance does not vary much due to replacement of the double effect ARS with the single effect ARS, however higher COP and exergy efficiency of the double effect system are achieved with much lower irreversible losses in the

Edge-promoting reconstruction of absorption and diffusivity in optical tomography

DEFF Research Database (Denmark)

Hannukainen, A.; Harhanen, Lauri Oskari; Hyvönen, N.

2015-01-01

In optical tomography a physical body is illuminated with near-infrared light and the resulting outward photon flux is measured at the object boundary. The goal is to reconstruct internal optical properties of the body, such as absorption and diffusivity. In this work, it is assumed that the imaged...... measurement noise model. The method is based on iteratively combining a lagged diffusivity step and a linearization of the measurement model of diffuse optical tomography with priorconditioned LSQR. The performance of the reconstruction technique is tested via three-dimensional numerical experiments...

Proceedings of the 1993 non-fluorocarbon insulation, refrigeration and air conditioning technology workshop

Energy Technology Data Exchange (ETDEWEB)

1994-09-01

Sessions included: HFC blown polyurethanes, carbon dioxide blown foam and extruded polystyrenes, plastic foam insulations, evacuated panel insulation, refrigeration and air conditioning, absorption and adsorption and stirling cycle refrigeration, innovative cooling technologies, and natural refrigerants. Selected papers have been indexed separately for inclusion in the Energy Science and Technology Database.

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.

Comparison and Analysis of Lithium Bromide-water Absorption Chillers Using Plastic Heat Transfer Tubes and Traditional Lithium Bromide-water Absorption Chillers

OpenAIRE

Xue-dong Zhang

2010-01-01

There are extensive applications of lithium bromide-water absorption chillers in industry, but the heat exchangers corrosion and refrigerating capacity loss are very difficult to be solved. In this paper, an experiment was conducted by using plastic heat transfer tubes instead of copper tubes. As an example, for a lithium bromide-water absorption chiller of refrigerating capacity of 35kW, the correlative performance of the lithium bromide-water absorption chiller using pl...

Simulation and experimental validation of the performance of a absorption refrigerator; Simulation und experimentelle Validierung des Betriebsverhaltens einer Absorptionskaeltemaschine

Energy Technology Data Exchange (ETDEWEB)

Olbricht, Michael; Luke, Andrea [Kassel Univ. (Germany). Fachgebiet Technische Thermodynamik

2015-07-01

The two biggest obstacles to a stronger market penetration of absorption refrigerators are their high cost and the size of the apparatus, which are due to the inaccurate methods for plant design. In order to contribute to an improved design a thermodynamic model is presented to describe the performance of a absorption refrigerator with the working fluid water/lithium. In this model, the processes are displayed in the single apparatus and coupled to each other in the systemic context. Thereby the interactions between the apparatus can specifically investigated and thus the process limiting component can be identified under the respective conditions. A validation of the simulation model and the boundary conditions used is done based on experimental data operating a self-developed absorption refrigerator. In the simulation, the heat transfer surfaces in accordance with the real system can be specified. The heat transport is taken into account based on typical values for the heat transfer in the individual apparatuses. Simulation results show good agreement with the experimental data. The physical relationships and influences externally defined operating parameters are correctly reproduced. Due to the chosen low heat transfer coefficient, the calculated cooling capacities by the model are below the experimentally measured. Finally, the possibilities and limitations are discussed by using the model and further improvement possibilities are suggested. [German] Die beiden groessten Hemmnisse fuer eine staerkere Marktdurchdringung von Absorptionskaeltemaschinen (AKM) sind deren hohe Anschaffungskosten sowie die Baugroesse der Apparate, die durch die ungenauen Methoden zur Anlagenauslegung begruendet sind. Als Beitrag fuer eine verbesserte Auslegung wird ein thermodynamisches Modell zur Beschreibung des Betriebsverhaltens einer AKM mit dem Arbeitsstoffpaar Wasser/Lithiumbromid vorgestellt. In diesem werden die Prozesse in den Einzelapparaten abgebildet und im systemischen

Energetic analysis of a commercial absorption refrigeration unit using an ammonia-water mixture

Directory of Open Access Journals (Sweden)

Josegil Jorge de Araújo

2017-09-01

Full Text Available The ROBUR® absorption refrigeration system (ARS, model ACF60, with a capacity of 17.5 kW, is tested, modeled and simulated in the steady state. To simulate the thermal load a heating system with secondary coolant was used, in which a programmable logic controller (PLC kept the inlet temperature EVA at around 285.15 K. The mathematical model used was based on balancing the mass, energy and ammonia concentrations and completed by closing equations such as, Newton's cooling equation. The mathematical model was implemented using the Engineering Equation Solver – EES®. The results obtained after modeling and a numerical permanent simulation are studied using the Duhring diagram. Potential points of internal heat recovery are visualized, and by using graphs of the binary mixture, it is possible to identify the thermodynamic states of all monitored points. The data obtained in the numerical simulation of the ARS was compared with data acquired in the actual tests of the ARS with the ROBUR® apparatus.

Prediction of thermophysical properties of mixed refrigerants using artificial neural network

International Nuclear Information System (INIS)

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

2011-01-01

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

Steady state simulation of a double-effect steam absorption chiller

Energy Technology Data Exchange (ETDEWEB)

Ahmed, M.S.A.M.S.; Gilani, S.I.U.H. [Universiti Teknologi Petronas, Tronoh, Perak (Malaysia). Dept. of Mechanical Engineering

2011-07-01

Absorption cooling systems have become increasingly popular in recent years from the viewpoint of energy and environment. Despite a lower coefficient of performance (COP) as compared to the vapor compression, absorption refrigeration systems are attractive for using inexpensive waste heat, solar, geothermal or biomass energy sources for which the cost of supply is negligible in many cases. In addition absorption refrigeration uses natural substances which do not contribute towards ozone depletion and global warming. Owing to the serious environmental problems and the price of the traditional energy resources, the use of industrial waste heat or renewable energy as the driving force for vapor absorption cooling systems is continuously increasing. A steady-state model is developed to predict the performance of an absorption refrigeration system using LiBr-water as working pair. Each component of the cycle is modelled based on mass and energy balances. The design point parameters are determined. The refrigeration effect, coefficient of performance and load factor are analyzed for different heat input. Simulation is carried out and the results are compared with actual data and showed good agreement.

Effect of operating conditions on the performance of the bubble pump of absorption-diffusion refrigeration cycles

Directory of Open Access Journals (Sweden)

Benhmidene Ali

2011-01-01

Full Text Available The mathematical model will be able to predict the operated condition (required tube diameters, heat input and submergence ratio….. That will result in a successful bubble pump design and hence a refrigeration unit. In the present work a one-dimensional two-fluid model of boiling mixing ammonia-water under constant heat flux is developed. The present model is used to predict the outlet liquid and vapor velocities and pumping ratio for different heat flux input to pump. The influence of operated conditions such as: ammonia fraction in inlet solution and tube diameter on the functioning of the bubble pump is presented and discussed. It was found that, the liquid velocity and pumping ratio increase with increasing heat flux, and then it decreases. Optimal heat flux depends namely on tube diameter variations. Vapour velocity increases linearly with increasing heat flux under designed conditions.

Simultaneous Absorptance and Thermal-Diffusivity Determination of Optical Components with Laser Calorimetry Technique

Science.gov (United States)

Wang, Yanru; Li, Bincheng

2012-11-01

The laser calorimetry (LCA) technique is used to determine simultaneously the absorptances and thermal diffusivities of optical components. An accurate temperature model, in which both the finite thermal conductivity and the finite sample size are taken into account, is employed to fit the experimental temperature data measured with an LCA apparatus for a precise determination of the absorptance and thermal diffusivity via a multiparameter fitting procedure. The uniqueness issue of the multiparameter fitting is discussed in detail. Experimentally, highly reflective (HR) samples prepared with electron-beam evaporation on different substrates (BK7, fused silica, and Ge) are measured with LCA. For the HR-coated sample on a fused silica substrate, the absorptance is determined to be 15.4 ppm, which is close to the value of 17.6 ppm, determined with a simplified temperature model recommended in the international standard ISO11551. The thermal diffusivity is simultaneously determined via multiparameter fitting to be approximately 6.63 × 10-7 m2 · s-1 with a corresponding square variance of 4.8 × 10-4. The fitted thermal diffusivity is in reasonably good agreement with the literature value (7.5 × 10-7 m2 · s -1). Good agreement is also obtained for samples with BK7 and Ge substrates.

Recent investigations on refrigerants for magnetic refrigerators

International Nuclear Information System (INIS)

Hashimoto, T.

1986-01-01

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

Standard GAX versus hybrid GAX absorption refrigeration cycle: From the view point of thermoeconomics

International Nuclear Information System (INIS)

Mehr, A.S.; Zare, V.; Mahmoudi, S.M.S.

2013-01-01

Highlights: • The SGAX cycle is found to be thermoeconomically efficient compared to HGAX cycle. • The HGAX cycle has higher COP and exergy efficiency compared to SGAX cycle. • Minimum product cost is found 180.5 $/GJ and 159.1 $/GJ for HGAX and SGAX, respectively. - Abstract: The main goal of this research is to compare thermoeconomic performance of a GAX absorption cycle and a hybrid GAX absorption cycle in which a compressor is employed to raise the absorber pressure. In order to do this, the ammonia–water standard GAX (SGAX) and hybrid GAX (HGAX) absorption refrigeration cycles are investigated and optimized from the viewpoints of thermodynamics and economics. Parametric studies are carried out and with the help of genetic algorithm (GA), the cycles’ performance is optimized based on the COP and exergy efficiency as well as the cost of unit product. Results indicate that although, compared to the GAX cycle, the HGAX cycle demonstrates a better performance from the view points of both the first and second laws of thermodynamics, the unit product cost for the HGAX cycle is higher. At the optimum operating conditions, the cost of unit product for the HGAX cycle is calculated as 180.5 $/GJ while the corresponding value for the SGAX cycle is obtained as 159.1 $/GJ. Also, the exergoeconomic analyses unfold that the condenser has the lowest exergoeconomic factor, f, in both the systems. In addition, inspired from nature, a new graphical plot is proposed to illustrate the fuel cost, product cost, capital investment and operating and maintenance cost and cost rates associated with the exergy destruction and losses within the system’s components

Second law analysis of double effect vapour absorption cooler system

International Nuclear Information System (INIS)

Gomri, Rabah; Hakimi, Riad

2008-01-01

In this paper, exergy analysis of double effect lithium bromide/water absorption refrigeration system is presented. The system consists of a second effect generator between the generator and condenser of the single effect absorption refrigeration system, including two solution heat exchangers between the absorber and the two generators. In order to simulate the refrigeration system by using a computer, a new set of computationally efficient formulations of thermodynamic properties of lithium bromide/water solution developed is used. The exergy analysis is carried out for each component of the system. All exergy losses that exist in double effect lithium bromide/water absorption system are calculated. In addition to the coefficient of performance and the exergetic efficiency of the system, the number of exergy of each component of the system is also estimated. This study suggests the component of the absorption refrigeration system that should be developed. The results show that the performance of the system increases with increasing low pressure generator (LPG) temperature, but decreases with increasing high pressure generator (HPG) temperature. The highest exergy loss occurs in the absorber and in the HPG, which therefore makes the absorber and HPG the most important components of the double effect refrigeration system

improvement to the design of a solid absorption solar refrigerator

African Journals Online (AJOL)

user

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

Free radicals in irradiated unstabilized polypropylene, as seen by diffuse reflection absorption-spectrophotometry

International Nuclear Information System (INIS)

Zagorski, Z.P.; Rafalski, A.

1998-01-01

The introduction of UV-Vis absorption spectrophotometry to the study of radiation chemistry of polymers has opened the possibility to investigate even very opaque samples. The virgin powder polypropylene, as obtained from the industrial production line, shows after irradiation unstable products of radiolysis. Until now they were investigated mainly by EPR method. Optical absorption spectra (by diffuse reflection spectrophotometry) contribute to better identification and study of changes in time, temperature and diffusion of reactive gases. Studying the formation of stable compounds, which do not produce EPR signal, we are able to examine these species on the basis of their electronic spectra. The most important results concern the peroxides in irradiated polypropylene

Parametric analysis and optimization for a combined power and refrigeration cycle

International Nuclear Information System (INIS)

Wang Jiangfeng; Dai Yiping; Gao Lin

2008-01-01

A combined power and refrigeration cycle is proposed, which combines the Rankine cycle and the absorption refrigeration cycle. This combined cycle uses a binary ammonia-water mixture as the working fluid and produces both power output and refrigeration output simultaneously with only one heat source. A parametric analysis is conducted to evaluate the effects of thermodynamic parameters on the performance of the combined cycle. It is shown that heat source temperature, environment temperature, refrigeration temperature, turbine inlet pressure, turbine inlet temperature, and basic solution ammonia concentration have significant effects on the net power output, refrigeration output and exergy efficiency of the combined cycle. A parameter optimization is achieved by means of genetic algorithm to reach the maximum exergy efficiency. The optimized exergy efficiency is 43.06% under the given condition

SIMS analysis of deuterium absorption and diffusion in austenitic Fe-Mn-C steels

International Nuclear Information System (INIS)

Dieudonne, T.; Chene, J.; Marchetti, L.; Jomard, F.; Wery, M.; Allely, C.; Cugy, P.; Scott, C.P.

2012-01-01

Austenitic Fe-Mn-C steels are Ultra High Strength Steels which may be used for the production of deep drawn automotive parts containing extremely high residual stress and strain levels. In consequence, hydrogen absorption occurring during the corrosion process in aqueous environments may enhance the sensitivity of these steels to different kinds of hydrogen-induced damage, in particular Stress Corrosion Cracking (SCC). In order to predict and prevent SCC, it is important to study the behaviour of hydrogen in these austenitic steels exposed to aqueous environments and in particular the dependence on the alloy chemistry and microstructure. SIMS profiles of deuterium introduced by cathodic charging in selected specimens were used to characterize the diffusion of hydrogen in these steels. This allowed to be studied the role of chemical composition and microstructure on the kinetics of H absorption at room temperature. The competition between bulk matrix diffusion and short-circuit diffusion phenomena along grain boundaries was investigated. The results show a strong dependence of H diffusion and distribution on the alloy chemistry and grain size. (authors)

The absoption refrigerator as a thermal transformer

OpenAIRE

Herrmann, Friedrich

2008-01-01

The absorption refrigerator can be considered a thermal transformer, i.e. a device that is analogous to the electric transformer. The analogy is based on a correspondence between the extensive quantities entropy and electric charge and that of the intensive variables temperature and electric potential.

Minority carrier diffusion lengths and absorption coefficients in silicon sheet material

Science.gov (United States)

Dumas, K. A.; Swimm, R. T.

1980-01-01

Most of the methods which have been developed for the measurement of the minority carrier diffusion length of silicon wafers require that the material have either a Schottky or an ohmic contact. The surface photovoltage (SPV) technique is an exception. The SPV technique could, therefore, become a valuable diagnostic tool in connection with current efforts to develop low-cost processes for the production of solar cells. The technique depends on a knowledge of the optical absorption coefficient. The considered investigation is concerned with a reevaluation of the absorption coefficient as a function of silicon processing. A comparison of absorption coefficient values showed these values to be relatively consistent from sample to sample, and independent of the sample growth method.

Configuration optimization of series flow double-effect water-lithium bromide absorption refrigeration systems by cost minimization

DEFF Research Database (Denmark)

Mussati, Sergio F.; Cignitti, Stefano; Mansouri, Seyed Soheil

2018-01-01

An optimal process configuration for double-effect water-lithium bromide absorption refrigeration systems with series flow – where the solution is first passed through the high-temperature generator – is obtained by minimization of the total annual cost for a required cooling capacity. To this end......) takes place entirely at the high-temperature zone, and the sizes and operating conditions of the other process units change accordingly in order to meet the problem specification with the minimal total annual cost. This new configuration was obtained for wide ranges of the cooling capacity (150–450 k.......9%, respectively. Most importantly, the obtained optimal solution eliminates the low-temperature solution heat exchanger from the conventional configuration, rendering a new process configuration. The energy integration between the weak and strong lithium bromide solutions (cold and hot streams, respectively...

Water cooling thermal power measurement in a vacuum diffusion pump

Directory of Open Access Journals (Sweden)

Luís Henrique Cardozo Amorin

2012-04-01

Full Text Available Diffusion vacuum pumps are used both in industry and in laboratory science for high vacuum production. For its operation they must be refrigerated, and it is done by circulating water in open circuit. Considering that, vacuum systems stays operating by hours, the water consumption may be avoided if the diffusion vacuum pumps refrigeration were done in closed circuit. However, it is necessary to know the diffusion vacuum pump thermal power (the heat transferred to circulate water by time units to implement one of these and get in the refrigeration system dimension. In this paper the diffusion vacuum pump thermal power was obtained by measuring water flow and temperature variation and was calculated through the heat quantity variation equation time function. The thermal power value was 935,6 W, that is 397 W smaller and 35 W bigger than, respectively, the maximum and minimum diffusion pump thermal power suggested by its operation manual. This procedure have been shown useful to precisely determine the diffusion pump thermal power or of any other system that needs to be refrigerated in water closed circuit.

Radial diffusion in the Uranian radiatian belts - Inferences from satellite absorption loss models

Science.gov (United States)

Hood, L. L.

1989-01-01

Low-energy charged particle (LECP) phase space density profiles available from the Voyager/1986 Uranus encounter are analyzed, using solutions of the time-averaged radial diffusion equation for charged particle transport in a dipolar planetary magnetic field. Profiles for lower-energy protons and electrons are first analyzed to infer radial diffusion rate as a function of L, assuming that satellite absorption is the dominant loss process and local sources for these particles are negligible. Satellite macrosignatures present in the experimentally derived profiles are approximately reproduced in several cases, lending credence to the loss model and indicating that magnetospheric distributed losses are not as rapid as satellite absorption near the minimum satellite L shells for the particles. Diffusion rates and L dependences are found to be similar to those previously inferred in the inner Jovian magnetosphere (Thomsen et al., 1977) and for the inner Saturnian magnetosphere (Hood, 1985). Profiles for higher energy electrons and protons are also analyzed using solutions that allow for the existence of significant particle sources as well as sinks. Possible implications for radial diffusion mechanisms in the Uranian radiation belts are discussed.

Architecture for Absorption Based Heaters

Science.gov (United States)

Moghaddam, Saeed; Chugh, Devesh

2018-04-24

An absorption based heater is constructed on a fluid barrier heat exchanging plate such that it requires little space in a structure. The absorption based heater has a desorber, heat exchanger, and absorber sequentially placed on the fluid barrier heat exchanging plate. The vapor exchange faces of the desorber and the absorber are covered by a vapor permeable membrane that is permeable to a refrigerant vapor but impermeable to an absorbent. A process fluid flows on the side of the fluid barrier heat exchanging plate opposite the vapor exchange face through the absorber and subsequently through the heat exchanger. The absorption based heater can include a second plate with a condenser situated parallel to the fluid barrier heat exchanging plate and opposing the desorber for condensation of the refrigerant for additional heating of the process fluid.

Excess Diffuse Light Absorption in Upper Mesophyll Limits CO2 Drawdown and Depresses Photosynthesis.

Science.gov (United States)

Earles, J Mason; Théroux-Rancourt, Guillaume; Gilbert, Matthew E; McElrone, Andrew J; Brodersen, Craig R

2017-06-01

In agricultural and natural systems, diffuse light can enhance plant primary productivity due to deeper penetration into and greater irradiance of the entire canopy. However, for individual sun-grown leaves from three species, photosynthesis is actually less efficient under diffuse compared with direct light. Despite its potential impact on canopy-level productivity, the mechanism for this leaf-level diffuse light photosynthetic depression effect is unknown. Here, we investigate if the spatial distribution of light absorption relative to electron transport capacity in sun- and shade-grown sunflower ( Helianthus annuus ) leaves underlies its previously observed diffuse light photosynthetic depression. Using a new one-dimensional porous medium finite element gas-exchange model parameterized with light absorption profiles, we found that weaker penetration of diffuse versus direct light into the mesophyll of sun-grown sunflower leaves led to a more heterogenous saturation of electron transport capacity and lowered its CO 2 concentration drawdown capacity in the intercellular airspace and chloroplast stroma. This decoupling of light availability from photosynthetic capacity under diffuse light is sufficient to generate an 11% decline in photosynthesis in sun-grown but not shade-grown leaves, primarily because thin shade-grown leaves similarly distribute diffuse and direct light throughout the mesophyll. Finally, we illustrate how diffuse light photosynthetic depression could overcome enhancement in canopies with low light extinction coefficients and/or leaf area, pointing toward a novel direction for future research. © 2017 American Society of Plant Biologists. All Rights Reserved.

Thermo-economic and environmental analyses based multi-objective optimization of vapor compression–absorption cascaded refrigeration system using NSGA-II technique

International Nuclear Information System (INIS)

Jain, Vaibhav; Sachdeva, Gulshan; Kachhwaha, Surendra Singh; Patel, Bhavesh

2016-01-01

Highlights: • It addresses multi-objective optimization study on cascaded refrigeration system. • Cascaded system is a promising decarburizing and energy efficient technology. • NSGA-II technique is used for multi-objective optimization. • Total annual product cost and irreversibility rate are simultaneously optimized. - Abstract: Present work optimizes the performance of 170 kW vapor compression–absorption cascaded refrigeration system (VCACRS) based on combined thermodynamic, economic and environmental parameters using Non-dominated Sort Genetic Algorithm-II (NSGA-II) technique. Two objective functions including the total irreversibility rate (as a thermodynamic criterion) and the total product cost (as an economic criterion) of the system are considered simultaneously for multi-objective optimization of VCACRS. The capital and maintenance costs of the system components, the operational cost, and the penalty cost due to CO_2 emission are included in the total product cost of the system. Three optimized systems including a single-objective thermodynamic optimized, a single-objective economic optimized and a multi-objective optimized are analyzed and compared. The results showed that the multi-objective design considers the combined thermodynamic and total product cost criteria better than the two individual single-objective thermodynamic and total product cost optimized designs.

Some comments about the comparison between a conventional and a solar powered absorption refrigeration system

International Nuclear Information System (INIS)

Corbella, O.D.; Garibotti, C.R.

1983-08-01

Two statements about the performance of solar refrigeration systems are discussed. First, concepts of efficiency and coefficient of performance are studied. Second, the influence of inflation and rise of fuel prices are considered, in relation to the comparison between solar and conventional refrigeration systems. (author)

Quantitative photoacoustic microscopy of optical absorption coefficients from acoustic spectra in the optical diffusive regime.

Science.gov (United States)

Guo, Zijian; Favazza, Christopher; Garcia-Uribe, Alejandro; Wang, Lihong V

2012-06-01

Photoacoustic (PA) microscopy (PAM) can image optical absorption contrast with ultrasonic spatial resolution in the optical diffusive regime. Conventionally, accurate quantification in PAM requires knowledge of the optical fluence attenuation, acoustic pressure attenuation, and detection bandwidth. We circumvent this requirement by quantifying the optical absorption coefficients from the acoustic spectra of PA signals acquired at multiple optical wavelengths. With the acoustic spectral method, the absorption coefficients of an oxygenated bovine blood phantom at 560, 565, 570, and 575 nm were quantified with errors of <3%. We also quantified the total hemoglobin concentration and hemoglobin oxygen saturation in a live mouse. Compared with the conventional amplitude method, the acoustic spectral method provides greater quantification accuracy in the optical diffusive regime. The limitations of the acoustic spectral method was also discussed.

Vacuum outgassing from diffuse-absorptive baffle materials

International Nuclear Information System (INIS)

Egert, C.M.; Basford, J.A.

1990-01-01

Quantitative measurements of outgassing for Martin black and a variety of metallic, diffuse absorptive baffle materials under development for stray light management are reported in this paper. Outgassing measurements were made during pumpdown from atmosphere at room temperature. Mass scans indicate water was the major outgassing species for all materials tested. Calibrated measurements of water vapor outgassing as a function of time were also made for each baffle material. Most baffle materials exhibited total water vapor outgassed during pumpdown of between 1 x 10 -5 and 4 x 10 -5 moles/cm 2 . Plasma sprayed beryllium, currently under development exhibited approximately an order of magnitude lower total water vapor outgassed during pumpdown

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.

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.

Noninvasive photoacoustic measurement of absorption coefficient using internal light irradiation of cylindrical diffusing fiber

Science.gov (United States)

Peng, Dong-qing; Zhu, Li-li; Li, Zhi-fang; Li, Hui

2017-09-01

Absorption coefficient of biological tissue is an important parameter in biomedicine, but its determination remains a challenge. In this paper, we propose a method using focusing photoacoustic imaging technique and internal light irradiation of cylindrical diffusing fiber (CDF) to quantify the target optical absorption coefficient. Absorption coefficients for ink absorbers are firstly determined through photoacoustic and spectrophotometric measurements at the same excitation, which demonstrates the feasibility of this method. Also, the optical absorption coefficients of ink absorbers with several concentrations are measured. Finally, the two-dimensional scanning photoacoustic image is obtained. Optical absorption coefficient measurement and simultaneous photoacoustic imaging of absorber non-invasively are the typical characteristics of the method. This method can play a significant role for non-invasive determination of blood oxygen saturation, the absorption-based imaging and therapy.

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

Method and refrigerants for replacing existing refrigerants in centrifugal compressors

International Nuclear Information System (INIS)

Kopko, W.L.

1991-01-01

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

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

Potential of the tractor-trailer and container segments as entry markets for a proposed refrigeration technology

Energy Technology Data Exchange (ETDEWEB)

Smith, S.A.; Davis, L.J.; Garrett, B.A.

1987-05-01

The refrigerated trailer and container segments of the transportation industry are evaluated as potential entry markets for a proposed absorption refrigeration technology. To perform this analysis the existing transportation refrigeration industry is characterized; this includes a description of the current refrigeration technology, rating systems, equipment manufacturers, maintenance requirements, and sales trends. This information indicates that the current transportation refrigeration industry is composed of two major competitors, Thermo King and Carrier. In addition, it has low profit potential, some barriers to entry and low growth potential. Data are also presented that characterize the transportation refrigeration consumers, specifically, major groups, market segmentation, consumer decision process, and buying criteria. This consumer information indicates that the majority of refrigerated trailer consumers are private carriers, and that the majority of refrigerated container consumers are shipping companies. Also, these consumers are primarily interested in buying reliable equipment at a low price, and are quite satisfied with existing refrigeration equipment.

Absorption heat pumps

International Nuclear Information System (INIS)

Formigoni, C.

1998-01-01

A brief description of the difference between a compression and an absorption heat pump is made, and the reasons why absorption systems have spread lately are given. Studies and projects recently started in the field of absorption heat pumps, as well as criteria usually followed in project development are described. An outline (performance targets, basic components) of a project on a water/air absorption heat pump, running on natural gas or LPG, is given. The project was developed by the Robur Group as an evolution of a water absorption refrigerator operating with a water/ammonia solution, which has been on the market for a long time and recently innovated. Finally, a list of the main energy and cost advantages deriving from the use of absorption heat pumps is made [it

The market for absorption refrigeration in Spain; Der Markt fuer Absorptionskaeltetechnik in Spanien

Energy Technology Data Exchange (ETDEWEB)

Paramo, M. [Enagas, Madrid (Spain)

1996-12-31

Due to the Spanish climate (hot summers throughout large parts of the country) the household and small consumers sector in this country has a substantial requirement for cold production. Today most industrial and commercial buildings here such as office blocks, shopping centres, hospitals, hotel etc. are equipped with air conditioning plants. Usually these are based on compression refrigeration plants. Beyond this air conditioning plants are now also beginning to become popular in one-family houses and flats, especially in southern and western Spain and along the Mediterranean coast. In most cases these plants, too, work with compression refrigeration, though it is not uncommon to find steam-based refrigeration systems. Both these types of system are driven by electricity. In the industrial sector, too, the market for refrigeration shows a very wide spectrum across a large variety of branches. (orig./HW) [Deutsch] In Spaniens HuK-Sektor (Haushalte und Kleinverbraucher) besteht aufgrund der herrschenden klimatischen Bedingungen (sehr warme Sommer in weiten Teilen des Landes) ein erheblicher Bedarf an der Erzeugung von Kaelte. Die meisten Industrie- und gewerblichen Gebaeude, wie Buerokomplexe, Einkaufszentren, Krankenhaeuser, Hotels, usw. sind mittlerweile mit Klimaanlagen ausgeruestet. Im allgemeinen handelt es sich hierbei um Kompressionskaelteanlagen. Vornehmlich in Sued- und Zentralspanien sowie an der Mittelmeerkueste haben Klimaanlagen inzwischen aber auch verstaerkt in Einfamilienhaeusern und Wohnungen Einzug gehalten. Vorwiegend sind Kompressionskaelteanlagen im Einsatz; haeufig sind aber auch Systeme anzutreffen, die auf Wasserdampfbasis arbeiten. Energietraeger ist bei beiden Systemen Strom. Der Markt fuer Kaelteerzeugung ist auch im industriellen Bereich sehr breitgefaechert und umfasst eine Vielzahl von Branchen. Der Loewenanteil entfaellt jedoch auf die Nahrungsmittelindustrie. (orig./HW)

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.

Design of an ejector cycle refrigeration system

International Nuclear Information System (INIS)

Grazzini, G.; Milazzo, A.; Paganini, D.

2012-01-01

Highlights: ► A design procedure is presented for an ejection refrigeration system. ► Properties of applicable operating fluids are presented and R245fa is selected. ► Real gas properties are used. ► The diffuser is designed with a profile that controls momentum change. ► Fluid friction is accounted for along all main components. - Abstract: A design procedure, based on a one-dimensional simulation, is presented for an ejection refrigeration system. Heat exchangers are included in the calculation, accounting for temperature differences between the fluids and for pressure losses. The ideal gas assumption, which is quite common in the literature concerning ejector systems, is avoided. Furthermore, the supersonic diffuser is designed with a continuous profile, without cylindrical piece, controlling the variation of momentum along the flow path and accounting for friction. At design conditions, this should reduce the irreversibility due to the normal shock. A comparison between different operating fluids is presented and R245fa is selected. The results of the design procedure and the expected performance, in terms of first and second law efficiency, are presented.

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.

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.

2017 German refrigeration and air conditioning meeting. Proceedings

International Nuclear Information System (INIS)

2017-01-01

This year's lecture programme includes 117 presentations in the five working departments of DKV and 10 lectures at the special event ''Energy-efficient air conditioning in data centres''. The main topics in the respective departments were: (1) Cryogenics: Space applications; Cryogenic plants; Cryomedicine and cryobiology; Components, developments; Processes and plants; Valves, design. (2) Basics: Evaporation, material values; evaporation, condensation; absorption; adsorption, latent storage; cycle simulation. (3) Components: CO 2 plant engineering and components; refrigerants; process control, adsorption, sublimation and storage technology; refrigerating machine oils, heat exchangers and corrosion; components 4.0, sensors and control technology; simulation of plant processes. (4) Cold application: Application; Application / Natural Refrigerants; Mobile Applications Car; Mobile Applications; Supermarket / Efficiency; Optimization / Efficiency. (5) Air conditioning and heat pump applications: load shifting, smart home, flexibility; heat sources and industrial heat pumps; modelling, simulations; energy concepts heat pumps and photovoltaics; monitoring, evaluation; technology trends / working materials. Six papers are separately analyzed for this database. [de

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.

ARTI refrigerant database

Energy Technology Data Exchange (ETDEWEB)

Calm, J.M.

1998-03-15

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

The use of absorption refrigeration systems in combined cycle power plants; Empleo de sistemas de refrigeracion por absorcion en plantas de ciclo combinado

Energy Technology Data Exchange (ETDEWEB)

Romero Paredes, H.; Ambriz, J.J.; Vargas, M.; Godinez, M.; Gomez, F.; Valdez, L.; Pantoja, G. [Universidad Autonoma Metropolitana, Unidad Iztapalapa, Departamento de Ingenieria de Procesos e Hidraulica, Mexico D. F. (Mexico)

1995-12-31

Day after day the electric power generation tends to be done in the most efficient way in order to diminish the generation costs and the rate of environmental pollution per KWh generated. This paper discusses the application of absorption refrigeration systems for the cooling of the air entering the compressor of a gas turbine in a combined cycle, in order to increase the mass air flow and with it the turbine output. The flows with remanent energy content that are not used in a combined cycle can be used for the operation of the absorption refrigeration system. This way, the required thermal energy for the cooling system is free. With this system it is possible to raise the gas turbine generation output from 5% to 25%. [Espanol] La generacion electrica dia con dia pretende realizarse de la manera mas eficiente posible con el objeto de disminuir los costos de generacion y la tasa de contaminacion ambiental por Kwh generado. En el presente trabajo se introduce la aplicacion de sistemas de refrigeracion por absorcion para el enfriamiento del aire de entrada al compresor de la turbina de gas de un ciclo combinado, con el objeto de aumentar el flujo masico del aire y con ello la potencia de salida de la turbina. Las corrientes con contenido remanente de energia termica que no se usan en una planta de ciclo combinado pueden servir para operar el sistema de refrigeracion por absorcion. De esta manera, la energia termica requerida para el sistema de enfriamiento es gratuita. Con este sistema es posible incrementar la potencia de generacion de la turbina de gas de 5 a 25%.

The use of absorption refrigeration systems in combined cycle power plants; Empleo de sistemas de refrigeracion por absorcion en plantas de ciclo combinado

Energy Technology Data Exchange (ETDEWEB)

Romero Paredes, H; Ambriz, J J; Vargas, M; Godinez, M; Gomez, F; Valdez, L; Pantoja, G [Universidad Autonoma Metropolitana, Unidad Iztapalapa, Departamento de Ingenieria de Procesos e Hidraulica, Mexico D. F. (Mexico)

1996-12-31

Day after day the electric power generation tends to be done in the most efficient way in order to diminish the generation costs and the rate of environmental pollution per KWh generated. This paper discusses the application of absorption refrigeration systems for the cooling of the air entering the compressor of a gas turbine in a combined cycle, in order to increase the mass air flow and with it the turbine output. The flows with remanent energy content that are not used in a combined cycle can be used for the operation of the absorption refrigeration system. This way, the required thermal energy for the cooling system is free. With this system it is possible to raise the gas turbine generation output from 5% to 25%. [Espanol] La generacion electrica dia con dia pretende realizarse de la manera mas eficiente posible con el objeto de disminuir los costos de generacion y la tasa de contaminacion ambiental por Kwh generado. En el presente trabajo se introduce la aplicacion de sistemas de refrigeracion por absorcion para el enfriamiento del aire de entrada al compresor de la turbina de gas de un ciclo combinado, con el objeto de aumentar el flujo masico del aire y con ello la potencia de salida de la turbina. Las corrientes con contenido remanente de energia termica que no se usan en una planta de ciclo combinado pueden servir para operar el sistema de refrigeracion por absorcion. De esta manera, la energia termica requerida para el sistema de enfriamiento es gratuita. Con este sistema es posible incrementar la potencia de generacion de la turbina de gas de 5 a 25%.

Dynamics of gas bubble growth in oil-refrigerant mixtures under isothermal decompression

Energy Technology Data Exchange (ETDEWEB)

Dias, Joao Paulo; Barbosa Junior, Jader R.; Prata, Alvaro T. [Federal University of Santa Catarina (UFSC), Florianopolis, SC (Brazil). Dept. of Mechanical Engineering], Emails: jpdias@polo.ufsc.br, jrb@polo.ufsc.br, prata@polo.ufsc.br

2010-07-01

This paper proposes a numerical model to predict the growth of gaseous refrigerant bubbles in oil-refrigerant mixtures with high contents of oil subjected to isothermal decompression. The model considers an Elementary Cell (EC) in which a spherical bubble is surrounded by a concentric and spherical liquid layer containing a limited amount of dissolved liquid refrigerant. The pressure reduction in the EC generates a concentration gradient at the bubble interface and the refrigerant is transported to the bubble by molecular diffusion. After a sufficiently long period of time, the concentration gradient in the liquid layer and the bubble internal pressure reach equilibrium and the bubble stops growing, having attained its stable radius. The equations of momentum and chemical species conservation for the liquid layer, and the mass balance at the bubble interface are solved via a coupled finite difference procedure to determine the bubble internal pressure, the refrigerant radial concentration distribution and the bubble growth rate. Numerical results obtained for a mixture of ISO VG10 ester oil and refrigerant HFC-134a showed that bubble growth dynamics depends on model parameters like the initial bubble radius, initial refrigerant concentration in the liquid layer, decompression rate and EC temperature. Despite its simplicity, the model showed to be a potential tool to predict bubble growth and foaming which may result from important phenomena occurring inside refrigeration compressors such as lubrication of sliding parts and refrigerant degassing from the oil stored in oil sump during compressor start-up. (author)

Thermoacoustic refrigeration

Science.gov (United States)

Garrett, Steven L.; Hofler, Thomas J.

1991-12-01

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

Two-phase flow modelling of a solar concentrator applied as ammonia vapor generator in an absorption refrigerator

Energy Technology Data Exchange (ETDEWEB)

Ortega, N. [Posgrado en Ingenieria (Energia), Universidad Nacional Autonoma de Mexico, Privada Xochicalco s/n, Temixco, Morelos 62580 (Mexico); Garcia-Valladares, O.; Best, R.; Gomez, V.H. [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, Privada Xochicalco s/n, Temixco, Morelos 62580 (Mexico)

2008-09-15

A detailed one-dimensional numerical model describing the heat and fluid-dynamic behavior inside a compound parabolic concentrator (CPC) used as an ammonia vapor generator has been developed. The governing equations (continuity, momentum, and energy) inside the CPC absorber tube, together with the energy equation in the tube wall and the thermal analysis in the solar concentrator were solved. The computational method developed is useful for the solar vapor generator design applied to absorption cooling systems. The effect on the outlet temperature and vapor quality of a range of CPC design parameters was analyzed. These parameters were the acceptance half-angle and CPC length, the diameter and coating of the absorber tube, and the manufacture materials of the cover, the reflector, and the absorber tube. It was found that the most important design parameters in order to obtain a higher ammonia-water vapor production are, in order of priority: the reflector material, the absorber tube diameter, the selective surface, and the acceptance half-angle. The direct ammonia-water vapor generation resulting from a 35 m long CPC was coupled to an absorption refrigeration system model in order to determine the solar fraction, cooling capacity, coefficient of performance, and overall efficiency during a typical day of operation. The results show that approximately 3.8 kW of cooling at -10{sup o}C could be produced with solar and overall efficiencies up to 46.3% and 21.2%, respectively. (author)

ARTI refrigerant database

Energy Technology Data Exchange (ETDEWEB)

Calm, J.M.

1997-02-01

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

ARTI refrigerant database

Energy Technology Data Exchange (ETDEWEB)

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

1999-01-01

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

ARTI refrigerant database

Energy Technology Data Exchange (ETDEWEB)

Calm, J.M.

1996-07-01

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

ARTI refrigerant database

Energy Technology Data Exchange (ETDEWEB)

Calm, J.M.

1996-11-15

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

Experimental validation of a model for diffusion-controlled absorption of organic compounds in the trachea

Energy Technology Data Exchange (ETDEWEB)

Gerde, P. [National Inst. for Working Life, Solna (Sweden); Muggenburg, B.A.; Thornton-Manning, J.R. [and others

1995-12-01

Most chemically induced lung cancer originates in the epithelial cells in the airways. Common conceptions are that chemicals deposited on the airway surface are rapidly absorbed through mucous membranes, limited primarily by the rate of blood perfusion in the mucosa. It is also commonly thought that for chemicals to induce toxicity at the site of entry, they must be either rapidly reactive, readily metabolizable, or especially toxic to the tissues at the site of entry. For highly lipophilic toxicants, there is a third option. Our mathematical model predicts that as lipophilicity increases, chemicals partition more readily into the cellular lipid membranes and diffuse more slowly through the tissues. Therefore, absorption of very lipophilic compounds will be almost entirely limited by the rate of diffusion through the epithelium rather than by perfusion of the capillary bed in the subepithelium. We have reported on a preliminary model for absorption through mucous membranes of any substance with a lipid/aqueous partition coefficient larger than one. The purpose of this work was to experimentally validate the model in Beagle dogs. This validated model on toxicant absorption in the airway mucosa will improve risk assessment of inhaled

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.

ARTI refrigerant database

Energy Technology Data Exchange (ETDEWEB)

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

1998-08-01

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

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%

Simulation Model for Dynamic Operation of Double-Effect Absorption Chillers

Directory of Open Access Journals (Sweden)

Ahmed Mojahid Sid Ahmed Mohammed Salih

2014-07-01

Full Text Available The development in the field of refrigeration and air conditioning systems driven by absorption cycles acquired a considerable importance recently. For commercial absorption chillers, an essential challenge for creating chiller model certainly is the shortage of components technical specifications. These kinds of specifications are usually proprietary for chillers producers. In this paper, a double-effect parallel-flow-type steam absorption chiller model based on thermodynamic and energy equations is presented. The chiller studied is Lithium bromide-water with capacity of 1250 RT (Refrigeration Tons. The governing equations of the dynamic operation of the chiller are developed. From available design information, the values of the overall heat transfer coefficients multiplied by the surface area are computed. The dynamic operation of the absorption chiller is simulated to study the performance of the system. The model is able to provide essential details of the temperature, concentration, and flow rate at each state point in the chiller.

Exergy based parametric analysis of a combined reheat regenerative thermal power plant and water–LiBr vapor absorption refrigeration system

International Nuclear Information System (INIS)

Gogoi, T.K.; Talukdar, K.

2014-01-01

Highlights: • Exergy analysis of a combined power–absorption cooling system is provided. • Exergetic efficiency of the power cycle and absorption cooling system are calculated. • Irreversibility in each component and total system irreversibility are calculated. • Effect of operating parameters on exergetic performance and irreversibility is analyzed. • Optimum operating parameters are identified based on energy and exergy based results. - Abstract: In this paper, exergy analysis of a combined reheat regenerative steam turbine (ST) based power cycle and water–LiBr vapor absorption refrigeration system (VARS) is presented. Exergetic efficiency of the power cycle and VARS, energy utilization factor (EUF) of the combined system (CS) and irreversibility in each system component are calculated. The effect of fuel flow rate, boiler pressure, cooling capacity and VARS components’ temperature on performance, component and total system irreversibility is analyzed. The second law based results indicate optimum performance at 150 bar boiler pressure and VARS generator, condenser, evaporator and absorber temperature of 80 °C, 37.5 °C, 15 °C and 35 °C respectively. The present exergy based results conform well to the first law based results obtained in a previous analysis done on the same combined system. Irreversibility distribution among various power cycle components shows the highest irreversibility in the cooling tower. Irreversibility of the exhaust flue gas leaving the boiler and the boiler are the next major contributors. Among the VARS components, exergy destruction in the generator is the highest followed by irreversibility contribution of the absorber, condenser and the evaporator

Numerical simulation and experimental results of horizontal tube falling film generator working in a NH3-LiNO3 absorption refrigeration system

International Nuclear Information System (INIS)

Herrera, J.V.; Garcia-Valladares, O.; Gomez, V.H.; Best, R.

2010-01-01

This paper describes the work made at the Centro de Investigacion en Energia in the development of an absorption refrigeration system for cooling and refrigeration applications with a capacity of 10 kW. The single effect unit utilizes ammonia-lithium nitrate as working pair and it is air cooled. The generator is a falling film type with horizontal tubes where the heating oil flows inside the tube bank and the ammonia-lithium nitrate solution flows as a falling film on the tube outside, where it is heated and ammonia vapor is generated. The generator consists of tree columns and four rows per column of horizontal tubes. The system was tested at controlled conditions with heating oil obtained from an electric resistance heating loop. A numerical model of the horizontal falling film generator was developed that divided the system into three different thermal elements: the flow inside the tube, the heat conduction in the tube wall and the falling film solution flow. The mathematical model was tested and validated with experimental data and a study of the influence of the heat transfer coefficient for ammonia-lithium nitrate solution in the numerical model was carried out. A comparison between experimental and numerical data for the heat flux in the system and the temperature profiles in the oil and solution flows shown a good degree of correlation.

Experimental results and thermodynamic analysis of a natural gas small scale cogeneration plant for power and refrigeration purposes

International Nuclear Information System (INIS)

Bazzo, Edson; Nacif de Carvalho, Alvaro; Matelli, José Alexandre

2013-01-01

In this work, experimental results are reported for a small scale cogeneration plant for power and refrigeration purposes. The plant includes a natural gas microturbine and an ammonia/water absorption chiller fired by steam. The system was tested under different turbine loads, steam pressures and chiller outlet temperatures. An evaluation based on the 1st and 2nd Laws of Thermodynamics was also performed. For the ambient temperature around 24 °C and microturbine at full load, the plant is able to provide 19 kW of saturated steam at 5.3 bar (161 °C), corresponding to 9.2 kW of refrigeration at −5 °C (COP = 0.44). From a 2nd law point-of-view, it was found that there is an optimal chiller outlet temperature that maximizes the chiller exergetic efficiency. As expected, the microturbine presented the highest irreversibilities, followed by the absorption chiller and the HRSG. In order to reduce the plant exergy destruction, it is recommended a new design for the HRSG and a new insulation for the exhaust pipe. -- Highlights: • A small scale cogeneration plant for power and refrigeration is proposed and analyzed. • The plant is based on a microturbine and a modified absorption chiller. • The plant is analysed based on 1st and 2nd laws of thermodynamics. • Experimental results are found for different power and refrigeration conditions. • The plant proved to be technically feasible

When are solar refrigerators less costly than on-grid refrigerators: A simulation modeling study.

Science.gov (United States)

Haidari, Leila A; Brown, Shawn T; Wedlock, Patrick; Connor, Diana L; Spiker, Marie; Lee, Bruce Y

2017-04-19

Gavi recommends solar refrigerators for vaccine storage in areas with less than eight hours of electricity per day, and WHO guidelines are more conservative. The question remains: Can solar refrigerators provide value where electrical outages are less frequent? Using a HERMES-generated computational model of the Mozambique routine immunization supply chain, we simulated the use of solar versus electric mains-powered refrigerators (hereafter referred to as "electric refrigerators") at different locations in the supply chain under various circumstances. At their current price premium, the annual cost of each solar refrigerator is 132% more than each electric refrigerator at the district level and 241% more at health facilities. Solar refrigerators provided savings over electric refrigerators when one-day electrical outages occurred more than five times per year at either the district level or the health facilities, even when the electric refrigerator holdover time exceeded the duration of the outage. Two-day outages occurring more than three times per year at the district level or more than twice per year at the health facilities also caused solar refrigerators to be cost saving. Lowering the annual cost of a solar refrigerator to 75% more than an electric refrigerator allowed solar refrigerators to be cost saving at either level when one-day outages occurred more than once per year, or when two-day outages occurred more than once per year at the district level or even once per year at the health facilities. Our study supports WHO and Gavi guidelines. In fact, solar refrigerators may provide savings in total cost per dose administered over electrical refrigerators when electrical outages are less frequent. Our study identified the frequency and duration at which electrical outages need to occur for solar refrigerators to provide savings in total cost per dose administered over electric refrigerators at different solar refrigerator prices. Copyright © 2017. Published

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.

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.

Analysis of a solar powered absorption system

International Nuclear Information System (INIS)

Said, S.A.M.; El-Shaarawi, M.A.I.; Siddiqui, M.U.

2015-01-01

Highlights: • Conventional absorption system modified to increase COP. • Results indicated increase of 10% in COP due to dephlegmator heat recovery. • Results indicated increase of 8% in COP due to refrigerant storage unit. • Results indicated increase of 18% in COP due to combined effect of modifications. • Simulation results indicated a very good agreement with the measured results. - Abstract: Today, fossil fuel is the primary extensively used source of energy. However, its negative impact on the environment have forced the energy research continuity to seriously consider renewable sources of energy. Solar energy, in particular, has been the main focus in this regard because it is a source of clean energy and naturally available. This study presents the design and analysis of a solar powered absorption refrigeration system modified to increase its coefficient of performance (COP). The modifications include recovering of waste heat from a dephlegmator and utilization of a refrigerant storage unit. The simulation results indicate an increase of 10% in the COP of the conventional design using dephlegmator heat recovery and an increase of 8% in the COP of the conventional design due to the use of a refrigerant storage. The analysis for the combined effect of modifications indicates an increase of 18% in the COP compared to conventional design. Calculated values of coefficient of performance indicate a very good agreement with the ones obtained based on measurement

Absorption and scattering of laser radiation by the diffusion flame of aviation kerosene

Energy Technology Data Exchange (ETDEWEB)

Gvozdev, S V; Glova, A F; Dubrovskii, V Yu; Durmanov, S T; Krasyukov, A G; Lysikov, A Yu; Smirnov, G V; Solomakhin, V B

2012-04-30

The absorption coefficient of the radiation of a repetitively pulsed Nd : YAG laser with an average output power up to 6 W and of a cw ytterbium optical fibre laser with an output power up to 3 kW was measured in the diffusion flame of aviation kerosene burning on a free surface in the atmospheric air. The absorption coefficient as a function of flame length, radiation power, and radiation intensity, which was varied in the {approx}10{sup 3} - 5 Multiplication-Sign 10{sup 4} W cm{sup -2} range, was obtained for two distances (1 and 2 cm) between the laser beam axis and the surface. The coefficient of radiation absorption by kerosene flame was compared with that in ethanol and kerosene - ethanol mixture flames. The radiation power scattered by a small segment of the kerosene flame irradiated by Nd : YAG laser radiation was measured as a function of longitudinal and azimuthal coordinates. An estimate was made of the total scattered radiation power.

Absorption and scattering of laser radiation by the diffusion flame of aviation kerosene

International Nuclear Information System (INIS)

Gvozdev, S V; Glova, A F; Dubrovskii, V Yu; Durmanov, S T; Krasyukov, A G; Lysikov, A Yu; Smirnov, G V; Solomakhin, V B

2012-01-01

The absorption coefficient of the radiation of a repetitively pulsed Nd : YAG laser with an average output power up to 6 W and of a cw ytterbium optical fibre laser with an output power up to 3 kW was measured in the diffusion flame of aviation kerosene burning on a free surface in the atmospheric air. The absorption coefficient as a function of flame length, radiation power, and radiation intensity, which was varied in the ∼10 3 - 5×10 4 W cm -2 range, was obtained for two distances (1 and 2 cm) between the laser beam axis and the surface. The coefficient of radiation absorption by kerosene flame was compared with that in ethanol and kerosene - ethanol mixture flames. The radiation power scattered by a small segment of the kerosene flame irradiated by Nd : YAG laser radiation was measured as a function of longitudinal and azimuthal coordinates. An estimate was made of the total scattered radiation power.

Absorption and scattering of laser radiation by the diffusion flame of aviation kerosene

Science.gov (United States)

Gvozdev, S. V.; Glova, A. F.; Dubrovskii, V. Yu; Durmanov, S. T.; Krasyukov, A. G.; Lysikov, A. Yu; Smirnov, G. V.; Solomakhin, V. B.

2012-04-01

The absorption coefficient of the radiation of a repetitively pulsed Nd : YAG laser with an average output power up to 6 W and of a cw ytterbium optical fibre laser with an output power up to 3 kW was measured in the diffusion flame of aviation kerosene burning on a free surface in the atmospheric air. The absorption coefficient as a function of flame length, radiation power, and radiation intensity, which was varied in the ~103 — 5×104 W cm-2 range, was obtained for two distances (1 and 2 cm) between the laser beam axis and the surface. The coefficient of radiation absorption by kerosene flame was compared with that in ethanol and kerosene — ethanol mixture flames. The radiation power scattered by a small segment of the kerosene flame irradiated by Nd : YAG laser radiation was measured as a function of longitudinal and azimuthal coordinates. An estimate was made of the total scattered radiation power.

THERMODYNAMIC ANALYSIS AND SIMULATION OF A NEW COMBINED POWER AND REFRIGERATION CYCLE USING ARTIFICIAL NEURAL NETWORK

Directory of Open Access Journals (Sweden)

Hossein Rezvantalab

2011-01-01

Full Text Available In this study, a new combined power and refrigeration cycle is proposed, which combines the Rankine and absorption refrigeration cycles. Using a binary ammonia-water mixture as the working fluid, this combined cycle produces both power and refrigeration output simultaneously by employing only one external heat source. In order to achieve the highest possible exergy efficiency, a secondary turbine is inserted to expand the hot weak solution leaving the boiler. Moreover, an artificial neural network (ANN is used to simulate the thermodynamic properties and the relationship between the input thermodynamic variables on the cycle performance. It is shown that turbine inlet pressure, as well as heat source and refrigeration temperatures have significant effects on the net power output, refrigeration output and exergy efficiency of the combined cycle. In addition, the results of ANN are in excellent agreement with the mathematical simulation and cover a wider range for evaluation of cycle performance.

When are solar refrigerators less costly than on-grid refrigerators: A simulation modeling study☆

Science.gov (United States)

Haidari, Leila A.; Brown, Shawn T.; Wedlock, Patrick; Connor, Diana L.; Spiker, Marie; Lee, Bruce Y.

2017-01-01

Background Gavi recommends solar refrigerators for vaccine storage in areas with less than eight hours of electricity per day, and WHO guidelines are more conservative. The question remains: Can solar refrigerators provide value where electrical outages are less frequent? Methods Using a HERMES-generated computational model of the Mozambique routine immunization supply chain, we simulated the use of solar versus electric mains-powered refrigerators (hereafter referred to as “electric refrigerators”) at different locations in the supply chain under various circumstances. Results At their current price premium, the annual cost of each solar refrigerator is 132% more than each electric refrigerator at the district level and 241% more at health facilities. Solar refrigerators provided savings over electric refrigerators when one-day electrical outages occurred more than five times per year at either the district level or the health facilities, even when the electric refrigerator holdover time exceeded the duration of the outage. Two-day outages occurring more than three times per year at the district level or more than twice per year at the health facilities also caused solar refrigerators to be cost saving. Lowering the annual cost of a solar refrigerator to 75% more than an electric refrigerator allowed solar refrigerators to be cost saving at either level when one-day outages occurred more than once per year, or when two-day outages occurred more than once per year at the district level or even once per year at the health facilities. Conclusion Our study supports WHO and Gavi guidelines. In fact, solar refrigerators may provide savings in total cost per dose administered over electrical refrigerators when electrical outages are less frequent. Our study identified the frequency and duration at which electrical outages need to occur for solar refrigerators to provide savings in total cost per dose administered over electric refrigerators at different solar

Functional Dependence of Thermodynamic and Thermokinetic Parameters of Refrigerants Used in Mine Air Refrigerators. Part 1 - Refrigerant R407C

Science.gov (United States)

Nowak, Bernard; Życzkowski, Piotr; Łuczak, Rafał

2017-03-01

The authors of this article dealt with the issue of modeling the thermodynamic and thermokinetic properties (parameters) of refrigerants. The knowledge of these parameters is essential to design refrigeration equipment, to perform their energy efficiency analysis, or to compare the efficiency of air refrigerators using different refrigerants. One of the refrigerants used in mine air compression refrigerators is R407C. For this refrigerant, 23 dependencies were developed, determining its thermodynamic and thermokinetic parameters in the states of saturated liquid, dry saturated vapour, superheated vapor, subcooled liquid, and in the two-phase region. The created formulas have been presented in Tables 2, 5, 8, 10 and 12, respectively. It should be noted that the scope of application of these formulas is wider than the range of changes of that refrigerant during the normal operation of mine refrigeration equipment. The article ends with the statistical verification of the developed dependencies. For this purpose, for each model correlation coefficients and coefficients of determination were calculated, as well as absolute and relative deviations between the given values from the program REFPROP 7 (Lemmon et al., 2002) and the calculated ones. The results of these calculations have been contained in Tables 14 and 15.

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.

Band shape of IR-absorption of complex molecules and restricted rotational diffusion

International Nuclear Information System (INIS)

Ivanov, E.N.; Umidulaev, Sh.U.

1989-01-01

The development of the theory of band shape (and Breadth) IR-absorption of complex molecules (regarding the molecules inside motions) is considered. It is supposed that a molecule fragment being responsible for IR-absorption takes part in the restricted rotational diffusion (RRD) with respect to the frame, and the molecule itself in general makes rotational motion (RM). Both kinds of motions are discussed in accordance with the theory of group motions representations. On the basis of correlative functions calculations of dipole moment a simple expression for the IR-absorption band shape have been obtained, which in itself uses to be the super position of two Lorencians with the semibreadths 2D 1 and 2D 1 +ν 2 0 (ν 2 0 +1D R accordingly (here D 1 is the coefficient of RM, D 2 is the coefficient of RRD, ν 2 0 is the well known function of RRD-cone divergence angle) in case of symmetric rotary abrasive disc. Analysis of experimental band shape of IR-absorption on the basis of the expression obtained allows to get information of MR-molecule parameters in general and RRD. It is really possible to determine the RRD-cone divergency angle from experimental weights of Lorencians. In accordance with experimental semibreadths the coefficient of RM D 1 and the coefficient of RRD D 2 are obtained. In conclusion it is noted that D 1 →0 (in the expression for the band shape of IR-absorption obtained), one of the Lorencians turns to the δ-function and finally there is an expression which describes IR-absorption band shape of molecules in polymer-mats. (author)

Thermodynamic analysis of a combined gas turbine, ORC cycle and absorption refrigeration for a CCHP system

International Nuclear Information System (INIS)

Mohammadi, Amin; Kasaeian, Alibakhsh; Pourfayaz, Fathollah; Ahmadi, Mohammad Hossein

2017-01-01

Highlights: • Thermodynamic analysis of a hybrid CCHP system. • Sensitivity analysis is performed on the most important parameters of the system. • Pressure ratio and gas turbine inlet temperature are the most effective parameters. - Abstract: Hybrid power systems are gained more attention due to their better performance and higher efficiency. Widespread use of these systems improves environmental situation as they reduce the amount of fossil fuel consumption. In this paper a hybrid system composed of a gas turbine, an ORC cycle and an absorption refrigeration cycle is proposed as a combined cooling, heating and power system for residential usage. Thermodynamic analysis is applied on the system. Also a parametric analysis is carried out to investigate the effect of different parameters on the system performance and output cooling, heating and power. The results show that under design conditions, the proposed plant can produce 30 kW power, 8 kW cooling and almost 7.2 ton hot water with an efficiency of 67.6%. Moreover, parametric analysis shows that pressure ratio and gas turbine inlet temperature are the most important and influential parameters. After these two, ORC turbine inlet temperature is the most effective parameter as it can change both net output power and energy efficiency of the system.

Finite time thermodynamics of power and refrigeration cycles

CERN Document Server

Kaushik, Shubhash C; Kumar, Pramod

2017-01-01

This book addresses the concept and applications of Finite Time Thermodynamics to various thermal energy conversion systems including heat engines, heat pumps, and refrigeration and air-conditioning systems. The book is the first of its kind, presenting detailed analytical formulations for the design and optimisation of various power producing and cooling cycles including but not limited to: • Vapour power cycles • Gas power cycles • Vapour compression cycles • Vapour absorption cycles • Rankine cycle coupled refrigeration systems Further, the book addresses the thermoeconomic analysis for the optimisation of thermal cycles, an important field of study in the present age and which is characterised by multi-objective optimization regarding energy, ecology, the environment and economics. Lastly, the book provides the readers with key techniques associated with Finite Time Thermodynamics, allowing them to understand the relevance of irreversibilitie s associated with real processes and the scientific r...

Diffuse-light absorption spectroscopy by fiber optics for detecting and quantifying the adulteration of extra virgin olive oil

Science.gov (United States)

Mignani, A. G.; Ciaccheri, L.; Ottevaere, H.; Thienpont, H.; Conte, L.; Marega, M.; Cichelli, A.; Attilio, C.; Cimato, A.

2010-09-01

A fiber optic setup for diffuse-light absorption spectroscopy in the wide 400-1700 nm spectral range is experimented for detecting and quantifying the adulteration of extra virgin olive oil caused by lower-grade olive oils. Absorption measurements provide spectral fingerprints of authentic and adulterated oils. A multivariate processing of spectroscopic data is applied for discriminating the type of adulterant and for predicting its fraction.

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

Cattaneo-Christov double-diffusion theory for three-dimensional flow of viscoelastic nanofluid with the effect of heat generation/absorption

Science.gov (United States)

Hayat, Tasawar; Qayyum, Sajid; Shehzad, Sabir Ali; Alsaedi, Ahmed

2018-03-01

The present research article focuses on three-dimensional flow of viscoelastic(second grade) nanofluid in the presence of Cattaneo-Christov double-diffusion theory. Flow caused is due to stretching sheet. Characteristics of heat transfer are interpreted by considering the heat generation/absorption. Nanofluid theory comprises of Brownian motion and thermophoresis. Cattaneo-Christov double-diffusion theory is introduced in the energy and concentration expressions. Such diffusions are developed as a part of formulating the thermal and solutal relaxation times framework. Suitable variables are implemented for the conversion of partial differential systems into a sets of ordinary differential equations. The transformed expressions have been explored through homotopic algorithm. Behavior of sundry variables on the velocities, temperature and concentration are scrutinized graphically. Numerical values of skin friction coefficients are also calculated and examined. Here thermal field enhances for heat generation parameter while reverse situation is noticed for heat absorption parameter.

Adaptation of closed cycle refrigeration system spectrum to radiation cryochemistry: γ-irradiation, ESR and optical absorption spectroscopy, ITL and RTL of frozen matrices at temperatures down to 14 K

International Nuclear Information System (INIS)

Mayer, J.; Plonka, A.; Ratajski, A.; Suwalski, J.P.; Wypych, M.

1978-01-01

The adaptation of the commercially available closed cycle refrigeration system Spectrim sup(TM) for radiation cryochemistry experiments with frozen matrices down to 14 K is described. The cold head of Spectrim sup(TM), equipped with vacuum shroud extensions and sample holders proper for the given type of experiments, was contained in lead shields, provided with special entrances for irradiation of samples with 60 Co γ-rays. The shroud extensions used for ESR and optical absorption measurements and the sample holders for isothermal luminescence and radiothermolumininescence measurements are described. (U.K.)

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

Science.gov (United States)

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

2017-01-01

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

Evaluation of Refrigerating and Air Conditioning Devices in Energy Cascade Systems under the Restriction of Carbon Dioxide Emissions

Science.gov (United States)

Shimazaki, Yoichi; Akisawa, Atsushi; Kashiwagi, Takao

It is necessary to introduce energy cascade systems into the industrial sector in Japan to reduce carbon dioxide emissions. The aim of this study is to evaluate the refrigerating and air conditioning devices in cases of introducing both energy cascade systems and thermal recycling systems in industries located around urban areas. The authors have developed an energy cascade model based on linear programming so as to minimize the total system costs with carbon taxes. Five cases are investigated. Limitation of carbon dioxide emissions results in the enhancement of heat cascading, where high temperature heat is supplied for process heating while low temperature one is shifted to refrigeration. It was found that increasing the amount of garbage combustor waste heat can reduce electric power for the turbo refrigerator by promoting waste heat driven ammonia absorption refrigerator.

Thermo- economical consideration of Regenerative organic Rankine cycle coupling with the absorption chiller systems incorporated in the trigeneration system

International Nuclear Information System (INIS)

Anvari, Simin; Taghavifar, Hadi; Parvishi, Alireza

2017-01-01

Highlights: • A new trigeneration cycle was studied from a new viewpoint of exergoeconomic and thermodynamic. • Organic Rankine and refrigeration cycles are used for recovery waste heat of cogeneration system. • Application of trigeneration cycles is advantageous in economical and thermodynamic aspects. - Abstract: In this paper, a combined cooling, heating and power cycle is proposed consisting of three sections of gas turbine and heat recovery steam generator cycle, Regenerative organic Rankine cycle, and absorption refrigeration cycle. This trigeneration cycle is subjected to a thorough thermodynamic and exergoeconomic analysis. The principal goal followed in the investigation is to address the thermodynamic and exergoeconomic of a trigeneration cycle from a new prospective such that the economic and thermodynamic viability of incorporating Regenerative organic Rankine cycle, and absorption refrigeration cycle to the gas turbine and heat recovery steam generator cycle is being investigated. Thus, the cost-effectiveness of the introduced method can be studied and further examined. The results indicate that adding Regenerative organic Rankine cycle to gas turbine and heat recovery steam generator cycle leads to 2.5% increase and the addition of absorption refrigeration cycle to the gas turbine and heat recovery steam generator/ Regenerative Organic Rankine cycle would cause 0.75% increase in the exergetic efficiency of the entire cycle. Furthermore, from total investment cost of the trigeneration cycle, only 5.5% and 0.45% results from Regenerative organic Rankine cycle and absorption refrigeration cycles, respectively.

Flammable refrigerants

NARCIS (Netherlands)

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

1999-01-01

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

Performance of refrigerating machineries with new refrigerants; Performance des machines frigorifiques avec les nouveaux refrigerants

Energy Technology Data Exchange (ETDEWEB)

Bailly, A; Jurkowski, R [CIAT, 01 - Culoz (France)

1998-12-31

This paper reports on a comparative study of the thermal performances of different refrigerants like R-22, R-134a, R-404A and R-407C when used as possible substitutes for the HCFC22 refrigerant in a given refrigerating machinery equipped with compact high performance plate exchangers. Thermal performances are compared in identical operating conditions. The behaviour of the two-phase exchange coefficient is analyzed with respect to the different parameters. The composition of the mixture after one year of operation has been analyzed too and the influence of oil on the performances is studied. (J.S.)

Performance of refrigerating machineries with new refrigerants; Performance des machines frigorifiques avec les nouveaux refrigerants

Energy Technology Data Exchange (ETDEWEB)

Bailly, A.; Jurkowski, R. [CIAT, 01 - Culoz (France)

1997-12-31

This paper reports on a comparative study of the thermal performances of different refrigerants like R-22, R-134a, R-404A and R-407C when used as possible substitutes for the HCFC22 refrigerant in a given refrigerating machinery equipped with compact high performance plate exchangers. Thermal performances are compared in identical operating conditions. The behaviour of the two-phase exchange coefficient is analyzed with respect to the different parameters. The composition of the mixture after one year of operation has been analyzed too and the influence of oil on the performances is studied. (J.S.)

Behavior of FFC refrigerants in the presence of refrigerant oils. Oelverhalten chlorfreier Kaeltemittel

Energy Technology Data Exchange (ETDEWEB)

Burke, M.; Kruse, H. (Hannover Univ. (Germany, F.R.). Inst. fuer Kaeltetechnik und Angewandte Waermetechnik)

1990-01-01

Looking for substitutes for the ozone-depleting refrigerants R12 and R22, investigations were made of the miscibility of FFC refrigerants (R23 - trifluoromethane CHF{sub 3}, R134a - tetrafluoroethane CH{sub 3}-CHF{sub 2}, and R152a - difluoroethane CH{sub 3}-CHF{sub 2}) with refrigerator oils. First experimental results reveal the refrigerants' behavior when mixed with mineral oils, alkylbenzene, PAG and ester-based oils. Mixtures of above refrigerants, especially R134a/R152a and R23/R152a as binary nonazeotropic mixtures, are considered conceivable substitutes. While addition of R23 reduces the mixture's flammability, addition of R152a improves the solubility of R134a in refrigerant oils. (orig./HW).

Graphical expression of thermodynamic characteristics of absorption process in ammonia-water system

Directory of Open Access Journals (Sweden)

Fortelný Zdeněk

2012-04-01

Full Text Available The adiabatic sorption is very interesting phenomenon that occurs when vapor of refrigerant is in contact with unsaturated liquid absorbent-refrigerant mixture and exchange of heat is forbid between the system and an environment. This contribution introduces new auxiliary lines that enable correct position determination of the adiabatic sorption process in the p-T-x diagram of ammoniawater system. The presented auxiliary lines were obtained from common functions for fast calculation of water-ammonia system properties. Absorption cycles designers often utilize p-t-x diagrams of working mixtures for first suggestion of new absorption cycles. The p-t-x diagrams enable fast correct determination of saturate states of liquid (and gaseous mixtures of refrigerants and absorbents. The working mixture isn’t only at saturated state during a real working cycle. If we know pressure and temperature of an unsaturated mixture, exact position determination is possible in the p-t-x diagrams too.

Refrigerants and environment

Science.gov (United States)

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

2017-11-01

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

Prediction of Dangerous Time in Case Hydrocarbon Refrigerant Leaks into Household Refrigerator Cabinet

Science.gov (United States)

Meguro, Takatoshi; Kaji, Nobufuji; Miyake, Kunihiro

Hydrocarbon refrigerators are now on sale in European countries. However, hydrocarbons are flammable. A common claim is that concentration of hydrocarbon in the refrigerator could exceed the lower explosive limit by a sudden leak and then a spark ignites a flame causing overpressure. There is the need of the studies on potential risks originated from the use of flammable refrigerants. Thus, the flow rate of the fresh air into the refrigerator cabinet has been defined experimentally, and the spatial average concentration in the refrigerator cabinet has been analyzed theoretically to predict the dangerous time in excess of the lower explosive limit.

Theoretical study on a novel dual-nozzle ejector enhanced refrigeration cycle for household refrigerator-freezers

International Nuclear Information System (INIS)

Zhou, Mengliu; Wang, Xiao; Yu, Jianlin

2013-01-01

Highlights: • A novel dual-nozzle ejector enhanced refrigeration cycle is proposed. • The novel cycle is evaluated by using the developed mathematical model. • The results show the performances of the novel cycle could be significantly improved. • The novel cycle shows its promise in household refrigerator-freezers applications. - Abstract: In this study, a novel dual-nozzle ejector enhanced refrigeration cycle is presented for dual evaporator household refrigerator-freezers. The proposed ejector equipped with two nozzles can efficiently recover the expansion work from cycle throttling processes and enhance cycle performances. The performances of the novel cycle are evaluated by using the developed mathematical model, and then compared with that of the conventional ejector enhanced refrigeration cycle and basic vapor-compression refrigeration cycle. The simulation results show that for the given operating conditions, the coefficient of performance (COP) of the novel cycle using refrigerant R134a is improved by 22.9–50.8% compared with that of the basic vapor-compression refrigeration cycle, and the COP improvement is 10.5–30.8% larger than that of the conventional ejector enhanced refrigeration cycle. The further simulation results of the novel cycle using refrigerant R600a indicate that the cycle COP and volumetric refrigeration capacity could be significantly improved

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

Energy Technology Data Exchange (ETDEWEB)

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

1998-12-31

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

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

International Nuclear Information System (INIS)

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

2014-01-01

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

Developments in magnetocaloric refrigeration

International Nuclear Information System (INIS)

Brueck, Ekkes

2005-01-01

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

Solar-driven refrigeration technologies; Koeltechnologieen op zonne-energie

Energy Technology Data Exchange (ETDEWEB)

De Cillis, S.; Infante Ferreira, C.A. [Technische Universiteit Delft, Delft (Netherlands); Krieg, J. [Unilever Foods and Health Research Institute, Vlaardingen (Netherlands)

2005-12-01

A review is presented of solar driven refrigeration technologies. A subdivision is made between electric driven and thermal driven systems. Their potential and stage of development are discussed. The electric driven systems include Stirling, thermo-acoustic, thermoelectric, electrochemical and membrane assisted absorption systems. The thermal driven systems include absorption and adsorption systems. A model is used to compare the performance of the different solutions. [Dutch] Dit artikel geeft een overzicht van zon-aangedreven koeltechnologieen. Er wordt onderscheid gemaakt tussen elektrisch en thermisch aangedreven systemen. Hun potentieel en niveau van ontwikkeling worden besproken. De elektrisch aangedreven systemen omvatten Stirling, thermo-akoestisch, thermo-elektrisch, elektrochemisch en membraanondersteund absorptiesystemen.De warmte-aangedreven systemen omvatten absorptie en adsorptie. Er wordt gebruik gemaakt van een model om de prestaties van de verschillende alternatieven onderling te vergelijken.

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.

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

Science.gov (United States)

Westra, Douglas G.

1993-01-01

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

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

Outlooks for the development of ozone-safe refrigerant production at the Minatom facilities

International Nuclear Information System (INIS)

Shatalov, V.V.; Orekhov, V.T.; Dedov, A.S.; Zakharov, V.Yu.; Golubev, A.N.; Tsarev, V.A.

2001-01-01

Results of activities undertaken at the All-Russian Research Institute of Chemical Technology since 1988, which were aimed at search of new methods of synthesis of ozone-safe refrigerants, using depleted uranium hexafluoride waste formed at gas-diffusion plants as fluorinating agent, are considered. It is pointed out that major advantages of the flowsheets making use of UF 6 versus traditional method consist in the fact that the processes are conducted in gas phase under normal pressure and moderate temperatures with UF 6 transfer into a more environmentally friendly form. Outlooks for expansion of production of ozone-safe refrigerants by the method described are discussed [ru

ARTI Refrigerant Database

Energy Technology Data Exchange (ETDEWEB)

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

1993-04-30

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

ARTI Refrigerant Database

Energy Technology Data Exchange (ETDEWEB)

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

1994-05-27

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

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.

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.

A study of alternative refrigerants for the refrigeration and air conditioning sector in Mauritius

Science.gov (United States)

Dreepaul, R. K.

2017-11-01

The most frequently used refrigerants in the refrigeration and air conditioning (RAC) sector in Mauritius are currently hydrochlorofluorocarbons (HCFC) and hydrofluorocarbons (HFC). However, because of their strong influence on global warming and the impact of HCFCs on the ozone layer, refrigerants such as ammonia (NH3), carbon dioxide (CO2) and Hydrocarbons (HC), having minimal impact on the environment, are being considered. So far, HCs have only been safely used in domestic refrigeration. Ammonia has been used mainly for industrial refrigeration whereas CO2 is still under study. In this paper, a comparative study of the various feasible alternatives is presented in a survey that was undertaken with major stake holders in the field. The retrofitting possibility of existing equipment was assessed and safety issues associated with each refrigerant were analysed. The major setback of hydrocarbons as a widely accepted refrigerant is its flammability which was considered as a major safety hazard by the majority of respondents in the survey and the main advantages are the improved equipment coefficient of performance (COP) and better TEWI factor. This resulted in a 12 % drop in energy consumption. Despite the excellent thermodynamic properties of ammonia, its use has mainly been confined to industrial refrigeration due to its toxicity. In Mauritius, the performance of ammonia in air conditioning is being evaluated on a pilot basis. The major setback of carbon dioxide as a refrigerant is the high operating pressure which is considered a safety hazard. The high initial investment cost and the lack of qualified maintenance technician is also an issue. The use of CO2 is mainly being considered in the commercial refrigeration sector.

Water absorption in brick masonry

NARCIS (Netherlands)

Brocken, H.J.P.; Smolders, H.R.

1996-01-01

The water absorption in brick, mortar that was cured separately, and masonry samples was studied using NMR. Models of the moisture transport are usually formulated on the basis of a diffusion equation. In the case of water absorption in separate brick and mortar samples, the moisture diffusivity in

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.

Thermodynamic performance of an auto-cascade ejector refrigeration cycle with mixed refrigerant R32 + R236fa

International Nuclear Information System (INIS)

Tan, Yingying; Wang, Lin; Liang, Kunfeng

2015-01-01

In this paper, an auto-cascade ejector refrigeration cycle (ACERC) is proposed to obtain lower refrigeration temperature based on conventional ejector refrigeration and auto-cascade refrigeration principle. The thermodynamic performance of ACERC is investigated theoretically. The zeotropic refrigerant mixture R32 + R236fa is used as its working fluid. A parametric analysis is conducted to evaluate the effects of some thermodynamic parameters on the cycle performance. The study shows that refrigerant mixture composition, condenser outlet temperature and evaporation pressure have effects on performance of ACERC. The theoretical results also indicate that the ACERC can achieve the lowest refrigeration temperature at the temperature level of −30 °C. The application of zeotropic refrigerant mixture auto-cascade refrigeration in the ejector refrigeration cycle can provide a new way to obtain lower refrigeration temperature utilizing low-grade thermal energy. - Highlights: • An auto-cascade ejector refrigerator with R32 + R236fa mixed refrigerant is proposed. • The cycle can obtain a refrigeration temperature at −30 °C temperature range. • The effects of some thermodynamic parameters on the cycle performance are evaluated

Artificial intelligent methods for thermodynamic evaluation of ammonia-water refrigeration systems

International Nuclear Information System (INIS)

Sencan, Arzu

2006-01-01

In this paper, Linear Regression and M5'Rules models within Data Mining Process and Artificial Neural Network (ANN) model for thermodynamic evaluation of ammonia-water absorption refrigeration systems was carried out. A new formulation based on ANN model is presented for the analysis of ammonia-water absorption refrigeration systems (AWRS) because the optimal result was obtained by using ANN Model. Thermodynamic analysis of the AWRS is very complex because of analytic functions used for calculating the properties of fluid couples and simulation programs. Therefore, it is extremely difficult to perform analysis of this system. COP and f are estimated depending on the temperatures of system component and concentration values. Using the weights obtained from the trained network a new formulation is presented for the calculation of the COP and f; the use of ANN is proliferating with high speed in simulation. The R 2 -values obtained when unknown data were used to the networks was 0.9996 and 0.9873 for the circulation ratio and COP respectively which is very satisfactory. The use of this new formulation, which can be employed with any programming language or spreadsheet program for the estimation of the circulation ratio and COP of AWRS, as described in this paper, may make the use of dedicated ANN software unnecessary

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

U.S. Residential Miscellaneous Refrigeration Products: Results from Amazon Mechanical Turk Surveys

Energy Technology Data Exchange (ETDEWEB)

Greenblatt, Jeffery B.; Young, Scott J.; Yang, Hung-Chia; Long, Timothy; Beraki, Bereket; Price, Sarah K.; Pratt, Stacy; Willem, Henry; Desroches, Louis-Benoit

2013-11-14

Amazon Mechanical Turk was used, for the first time, to collect statistically representative survey data from U.S. households on the presence, number, type and usage of refrigerators, freezers, and various “miscellaneous” refrigeration products (wine/beverage coolers, residential icemakers and non-vapor compression refrigerators and freezers), along with household and demographic information. Such products have been poorly studied to date, with almost no information available about shipments, stocks, capacities, energy use, etc. A total of 9,981 clean survey responses were obtained from five distinct surveys deployed in 2012. General refrigeration product survey responses were weighted to demographics in the U.S. Energy Information Administration’s Residential Energy Consumption Survey 2009 dataset. Miscellaneous refrigeration product survey responses were weighted according to demographics of product ownership found in the general refrigeration product surveys. Model number matching for a portion of miscellaneous refrigeration product responses allowed validation of refrigeration product characteristics, which enabled more accurate estimates of the penetrations of these products in U.S. households. We estimated that there were 12.3±1.0 million wine/beverage coolers, 5.5(–3.5,+3.2) million residential icemakers and 4.4(–2.7,+2.3) million non-vapor compression refrigerators in U.S. households in 2012. (All numerical results are expressed with ranges indicating the 95% confidence interval.) No evidence was found for the existence of non-vapor compression freezers. Moreover, we found that 15% of wine/beverage coolers used vapor compression cooling technology, while 85% used thermoelectric cooling technology, with the vast majority of thermoelectric units having capacities of less than 30 wine bottles (approximately 3.5 cubic feet). No evidence was found for the existence of wine/beverage coolers with absorption cooling technology. Additionally, we estimated

U.S. Residential Miscellaneous Refrigeration Products: Results from Amazon Mechanical Turk Surveys

Energy Technology Data Exchange (ETDEWEB)

Greenblatt, Jeffery B. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Young, Scott J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Yang, Hung-Chia [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Long, Timothy [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Beraki, Bereket [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Price, Sarah K. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Pratt, Stacy [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Willem, Henry [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Desroches, Louis-Benoit [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2013-04-01

Amazon Mechanical Turk was used, for the first time, to collect statistically representative survey data from U.S. households on the presence, number, type and usage of refrigerators, freezers, and various “miscellaneous” refrigeration products (wine/beverage coolers, residential icemakers and non-vapor compression refrigerators and freezers), along with household and demographic information. Such products have been poorly studied to date, with almost no information available about shipments, stocks, capacities, energy use, etc. A total of 9,820 clean survey responses were obtained from four distinct surveys deployed in 2012. General refrigeration product survey responses were weighted to demographics in the U.S. Energy Information Administration’s Residential Energy Consumption Survey 2009 dataset. Miscellaneous refrigeration product survey responses were weighted according to demographics of product ownership found in the general refrigeration product surveys. Model number matching for a portion of miscellaneous refrigeration product responses allowed validation of refrigeration product characteristics, which enabled more accurate estimates of the penetrations of these products in U.S. households. We estimated that there were 12.3±1.0 million wine/beverage coolers, 5.5(–3.5,+3.2) million residential icemakers and 2.9(–2.5,+4.5) million non-vapor compression refrigerators in U.S. households in 2012. (All numerical results are expressed with ranges indicating the 95% confidence interval.) No evidence was found for the existence of non-vapor compression freezers. Moreover, we found that 15% of wine/beverage coolers used vapor compression cooling technology, while 85% used thermoelectric cooling technology, with the vast majority of thermoelectric units having capacities of less than 30 wine bottles (approximately 3.5 cubic feet). No evidence was found for the existence of wine/beverage coolers with absorption cooling technology. Additionally, we estimated

Evolution of absorption machines; Evolution des machines a absorption

Energy Technology Data Exchange (ETDEWEB)

Soide, I; Klemsdal, E [Gaz de France (GDF), 75 - Paris (France); Le Goff, P; Hornut, J M [LSGC-ENSIC, 54 - Nancy (France)

1998-12-31

Most of todays absorption air-conditioning machineries use the lithium bromide-water pair. The most performing can operate at a 150-160 deg. C, the temperature being limited by the corrosion resistance of metals with respect to LiBr solutions. Also, there is a revival of interest for water-ammonia systems. These systems require the use of a rectification column which reduces the coefficient of performance. Higher thermal performances are reached with hydrocarbon pairs and ternary mixtures (water-methanol-LiBr etc..). This paper presents different schemes of refrigerating heat pumps based on these different systems. (J.S.)

Evolution of absorption machines; Evolution des machines a absorption

Energy Technology Data Exchange (ETDEWEB)

Soide, I.; Klemsdal, E. [Gaz de France (GDF), 75 - Paris (France); Le Goff, P.; Hornut, J.M. [LSGC-ENSIC, 54 - Nancy (France)

1997-12-31

Most of todays absorption air-conditioning machineries use the lithium bromide-water pair. The most performing can operate at a 150-160 deg. C, the temperature being limited by the corrosion resistance of metals with respect to LiBr solutions. Also, there is a revival of interest for water-ammonia systems. These systems require the use of a rectification column which reduces the coefficient of performance. Higher thermal performances are reached with hydrocarbon pairs and ternary mixtures (water-methanol-LiBr etc..). This paper presents different schemes of refrigerating heat pumps based on these different systems. (J.S.)

10 CFR 431.62 - Definitions concerning commercial refrigerators, freezers and refrigerator-freezers.

Science.gov (United States)

2010-01-01

... functional characteristics that affect energy consumption. Commercial refrigerator, freezer, and refrigerator... formed by the plane of the door, when the equipment is viewed in cross-section; and (2) For equipment...

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

Energy Technology Data Exchange (ETDEWEB)

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

2004-01-01

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

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

Environment-friendly refrigeration - Switzerland moves forward

International Nuclear Information System (INIS)

Stohler, F.

2003-01-01

This article presents an interview with Silvan Schaller, president of the Swiss Refrigeration Society SVK and head of a leading Swiss industrial refrigeration company, on the subject of the implementation of new Swiss materials legislation that regulates the use of various refrigerants. In particular, the co-operation between the Society and the regulatory authorities is stressed. The reasons behind the regulations - the protection of the environment and, in particular, the ozone layer - are discussed as are the efforts required by industry to meet them. Future refrigeration technologies and the choice of refrigerants are examined. Measures that will have to be taken by the companies in the refrigeration sector, such as the additional training of personnel and the monitoring of the disposal of wastes, are examined. For the future, the goal of reducing the energy consumption of refrigeration installations is noted

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)

Regulating Power from Supermarket Refrigeration

DEFF Research Database (Denmark)

O'Connell, Niamh; Madsen, Henrik; Pinson, Pierre

2014-01-01

the Danfoss refrigeration test centre. The complexities of modelling demand response are demonstrated through simulation. Simulations are conducted by placing the identified model in a direct-control demand response architecture, with power reference tracking using model predictive control. The energylimited......This paper presents an analysis of the demand response capabilities of a supermarket refrigeration system, with a particular focus on the suitability for participation in the regulating power market. An ARMAX model of a supermarket refrigeration system is identified using experimental data from...... nature of demand response from refrigeration is identified as the key consideration when considering participation in the regulating power market. It is demonstrated that by restricting the operating regions of the supermarket refrigeration system, a simple relationship can be found between the available...

Absorption and Metabolism of Xanthophylls

Directory of Open Access Journals (Sweden)

Eiichi Kotake-Nara

2011-06-01

Full Text Available Dietary carotenoids, especially xanthophylls, have attracted significant attention because of their characteristic biological activities, including anti-allergic, anti-cancer, and anti-obese actions. Although no less than forty carotenoids are ingested under usual dietary habits, only six carotenoids and their metabolites have been found in human tissues, suggesting selectivity in the intestinal absorption of carotenoids. Recently, facilitated diffusion in addition to simple diffusion has been reported to mediate the intestinal absorption of carotenoids in mammals. The selective absorption of carotenoids may be caused by uptake to the intestinal epithelia by the facilitated diffusion and an unknown excretion to intestinal lumen. It is well known that β-carotene can be metabolized to vitamin A after intestinal absorption of carotenoids, but little is known about the metabolic transformation of non provitamin A xanthophylls. The enzymatic oxidation of the secondary hydroxyl group leading to keto-carotenoids would occur as a common pathway of xanthophyll metabolism in mammals. This paper reviews the absorption and metabolism of xanthophylls by introducing recent advances in this field.

Absorption and metabolism of xanthophylls.

Science.gov (United States)

Kotake-Nara, Eiichi; Nagao, Akihiko

2011-01-01

Dietary carotenoids, especially xanthophylls, have attracted significant attention because of their characteristic biological activities, including anti-allergic, anti-cancer, and anti-obese actions. Although no less than forty carotenoids are ingested under usual dietary habits, only six carotenoids and their metabolites have been found in human tissues, suggesting selectivity in the intestinal absorption of carotenoids. Recently, facilitated diffusion in addition to simple diffusion has been reported to mediate the intestinal absorption of carotenoids in mammals. The selective absorption of carotenoids may be caused by uptake to the intestinal epithelia by the facilitated diffusion and an unknown excretion to intestinal lumen. It is well known that β-carotene can be metabolized to vitamin A after intestinal absorption of carotenoids, but little is known about the metabolic transformation of non provitamin A xanthophylls. The enzymatic oxidation of the secondary hydroxyl group leading to keto-carotenoids would occur as a common pathway of xanthophyll metabolism in mammals. This paper reviews the absorption and metabolism of xanthophylls by introducing recent advances in this field.

Visualization and quantification of heterogeneous diffusion rates in granodiorite samples by X-ray absorption imaging. Diffusion within gouge materials, altered rim and intact rock matrix

Energy Technology Data Exchange (ETDEWEB)

Altman, S.J.; Tidwell, V.C. [Sandia National Laboratories, Albuquerque, NM (United States); Uchida, M. [Japan Nuclear Cycle Development Inst., Ibaraki (Japan)

2001-08-01

Matrix diffusion is one of the most important contaminant migration retardation processes in crystalline rocks. Performance assessment calculations in various countries assume that only the area of the fracture surface where advection is active provides access to the rock matrix. However, accessibility to the matrix could be significantly enhanced with diffusion into stagnant zones, fracture fillings, and through an alteration rim in the matrix. Laboratory visualization experiments were conducted on granodiorite samples to investigate and quantify diffusion rates within different zones of a Cretaceous granodiorite. Samples were collected from the Kamaishi experimental site in the northern part of the main island of Japan. Diffusion of iodine out of the sample is visualized and rates are measured using x-ray absorption imaging. X-ray images allow for measurements of relative iodine concentration and relative iodine mass as a function of time and two-dimensional space at a sub-millimeter spatial resolution. In addition, two-dimensional heterogeneous porosity fields (at the same resolution as the relative concentration fields) are measured. This imaging technique allows for a greater understanding of the spatial variability of diffusion rates than can be accomplished with standard bulk measurements. It was found that diffusion rates were fastest in partially gouge-filled fractures. Diffusion rates in the recrystallized calcite-based fracture-filling material were up to an order of magnitude lower than in gouge-filled fractures. Diffusion in altered matrix around the fractures was over an order of magnitude lower than that in the gouge-filled fractures. Healed fractures did not appear to have different diffusion rates than the unaltered matrix.

Visualization and quantification of heterogeneous diffusion rates in granodiorite samples by X-ray absorption imaging. Diffusion within gouge materials, altered rim and intact rock matrix

International Nuclear Information System (INIS)

Altman, S.J.; Tidwell, V.C.; Uchida, M.

2001-01-01

Matrix diffusion is one of the most important contaminant migration retardation processes in crystalline rocks. Performance assessment calculations in various countries assume that only the area of the fracture surface where advection is active provides access to the rock matrix. However, accessibility to the matrix could be significantly enhanced with diffusion into stagnant zones, fracture fillings, and through an alteration rim in the matrix. Laboratory visualization experiments were conducted on granodiorite samples to investigate and quantify diffusion rates within different zones of a Cretaceous granodiorite. Samples were collected from the Kamaishi experimental site in the northern part of the main island of Japan. Diffusion of iodine out of the sample is visualized and rates are measured using x-ray absorption imaging. X-ray images allow for measurements of relative iodine concentration and relative iodine mass as a function of time and two-dimensional space at a sub-millimeter spatial resolution. In addition, two-dimensional heterogeneous porosity fields (at the same resolution as the relative concentration fields) are measured. This imaging technique allows for a greater understanding of the spatial variability of diffusion rates than can be accomplished with standard bulk measurements. It was found that diffusion rates were fastest in partially gouge-filled fractures. Diffusion rates in the recrystallized calcite-based fracture-filling material were up to an order of magnitude lower than in gouge-filled fractures. Diffusion in altered matrix around the fractures was over an order of magnitude lower than that in the gouge-filled fractures. Healed fractures did not appear to have different diffusion rates than the unaltered matrix

Optimal design of solid oxide fuel cell, ammonia-water single effect absorption cycle and Rankine steam cycle hybrid system

Science.gov (United States)

Mehrpooya, Mehdi; Dehghani, Hossein; Ali Moosavian, S. M.

2016-02-01

A combined system containing solid oxide fuel cell-gas turbine power plant, Rankine steam cycle and ammonia-water absorption refrigeration system is introduced and analyzed. In this process, power, heat and cooling are produced. Energy and exergy analyses along with the economic factors are used to distinguish optimum operating point of the system. The developed electrochemical model of the fuel cell is validated with experimental results. Thermodynamic package and main parameters of the absorption refrigeration system are validated. The power output of the system is 500 kW. An optimization problem is defined in order to finding the optimal operating point. Decision variables are current density, temperature of the exhaust gases from the boiler, steam turbine pressure (high and medium), generator temperature and consumed cooling water. Results indicate that electrical efficiency of the combined system is 62.4% (LHV). Produced refrigeration (at -10 °C) and heat recovery are 101 kW and 22.1 kW respectively. Investment cost for the combined system (without absorption cycle) is about 2917 kW-1.

Transition to New Refrigerants

Science.gov (United States)

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

Effect of incident beam and diffuse radiation on par absorption, photosynthesis and transpiration of sitka spruce - a simulation study

International Nuclear Information System (INIS)

Wang, Y.P.; Jarvis, P.G.

1990-01-01

A simulation model, Maestro, is used to study the influence of beam fraction in the incident radiation and the radiance distribution of the sky diffuse radiation on PAR absorption, photosynthesis and transpiration of a Sitka spruce (Picea sitchensis (Bong.) Carr) tree crown. It is concluded that inaccurate separation of beam and diffuse radiation leads to significant errors in estimating the amounts of PAR absorbed, photosynthesis and transpiration by a tree in the stand. Much more attention should be paid to adequate descriptions of the radiance distribution of the sky diffuse radiation under different sky conditions. A useful approach is proposed for simulating the incident global radiaiton in a physiological, process-based model

Designing the lithium bromide air conditioning absorption system for a bus

International Nuclear Information System (INIS)

Yusoff Ali; Kamaruzzaman Sopian; Hariadi

2006-01-01

A system of air-conditioning using Lithium Bromide absorption system is used as an alternative refrigerant that will not pollute the atmosphere. Lithium Bromide is a chemical salt soluble in water. There is a big difference between vapour compression system and LiBr 2 absorption system. The absorption air conditioning system is made of a generator, a condenser, an evaporator and an absorber with necessary pumps and piping. When LiBr 2 solution is heated under low pressure, water will evaporate first, while LiBr 2 will remain in the solution and will become more concentrated. The water is the refrigerant in this system. The generator, where the water is vapourised, is heated using an electric heater or solar energy. The LiBr 2 weak solution under low pressure in the generator is heated and the water evaporate into vapour. The vapour produced is then cooled in the condenser and then expanded into the evaporator. The refrigerant (water) in evaporator change phase from liquid to vapour by absorbing heat from cooling water, which flow in the coil in the evaporator. The chilled water obtained is then pumped into the fan coil, which will be used in conditioning the passenger area of the bus. The water vapour from the evaporator is absorbed into LiBr 2 solution in the absorber, forming a weak solution of LiBr 2 . the weak solution from the absorber is then pumped back to the generator to regenerate. The absorption system does not use compressor, but requires pumps that need lower input power compared to that of a compressor. The system is considered as a new application for the bus. This will have great potential and will be environmentally friendly. The model in this study will be used for calculation of the cooling load for the bus

Simultaneous measurement of thermal diffusivity and effective infrared absorption coefficient in IR semitransparent and semiconducting n-CdMgSe crystals using photothermal radiometry

Energy Technology Data Exchange (ETDEWEB)

Pawlak, M., E-mail: mpawlak@fizyka.umk.pl [Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziądzka 5/7, Toruń (Poland); Maliński, M. [Department of Electronics and Computer Science, Koszalin University of Technology, 2 Śniadeckich St., Koszalin 75-453 (Poland)

2015-01-10

Highlights: • The new method of determination of the effective infrared absorption coefficient is presented. • The method can be used for transparent samples for the excitation radiation. • The effect of aluminum foil on the PTR signal in a transmission configuration is discussed. - Abstract: In this paper we propose a new procedure of simultaneous estimation of the effective infrared optical absorption coefficient and the thermal diffusivity of solid state samples using the photothermal infrared radiometry method in the transmission configuration. The proposed procedure relies on the analysis of the frequency dependent signal obtained from the samples covered with thin aluminum foil. This method can be applied for both optically opaque and transparent samples. The proposed method is illustrated with the results of the thermal diffusivity and the effective IR absorption coefficient obtained for several Cd{sub 1−x}Mg{sub x}Se crystals.

Influence of the nozzle angle on refrigeration performance of a gas wave refrigerator

Science.gov (United States)

Liu, P.; Zhu, Y.; Wang, H.; Zhu, C.; Zou, J.; Wu, J.; Hu, D.

2017-05-01

A gas wave refrigerator (GWR) is a novel refrigerating device that refrigerates a medium by shock waves and expansion waves generated by gas pressure energy. In a typical GWR, the injection energy losses between the nozzle and the expansion tube are essential factors which influence the refrigeration efficiency. In this study, numerical simulations are used to analyze the underlying mechanism of the injection energy losses. The results of simulations show that the vortex loss, mixing energy loss, and oblique shock wave reflection loss are the main factors contributing to the injection energy losses in the expansion tube. Furthermore, the jet angle of the gas is found to dominate the injection energy losses. Therefore, the optimum jet angle is theoretically calculated based on the velocity triangle method. The value of the optimum jet angle is found to be 4^{circ }, 8^{circ }, and 12^{circ } when the refrigeration efficiency is the first-order, second-order, and third-order maximum value over all working ranges of jet frequency, respectively. Finally, a series of experiments are conducted with the jet angle ranging from -4^{circ } to 12^{circ } at a constant expansion ratio. The results indicate the optimal jet angle obtained by the experiments is in good agreement with the calculated value. The isentropic refrigeration efficiency increased by about 4 % after the jet angle was optimized.

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.

THERMODYNAMIC PROPERTIES OF SELECTED HFC REFRIGERANTS

Science.gov (United States)

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

OPTIMIZATION OF A DOUBLE EFFECT LIBR-H20 ABSORPTION ...

African Journals Online (AJOL)

The effect of the effectiveness of the heat exchangers on the COP of the system are olso anolysed using the developed program. INTRODUCTION. One possible way of greatly increasing the COP of an absorption refrigeration system is incorporating a second-effect or second-stage generator. Due to its higher COP, the ...

Design of refrigeration system using refrigerant R134a for macro compartment

Science.gov (United States)

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

2017-10-01

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

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.

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.

An experimental investigation on a novel ejector enhanced refrigeration cycle applied in the domestic refrigerator-freezer

International Nuclear Information System (INIS)

Wang, Xiao; Yu, Jianlin

2015-01-01

This paper presents an experimental investigation on a NERC (novel ejector enhanced refrigeration cycle) applied in the domestic refrigerator-freezer (BCD-249). Experimental studies were conducted to validate the NERC system feasibility in a practical NERC based refrigerator-freezer prototype. The system performances of energy consumption, ejector pressure lift ratio and compressor power were compared under different combinations of system configuration parameters. The results showed that the NERC system could effectively reduce the thermodynamic losses in the throttle processing. The minimum energy consumption of 0.520 kWh 24 h"−"1 was obtained for the NERC prototype, indicating 5.45% energy consumption reduction compared with the conventional domestic refrigerator-freezer. Furthermore, the effects of system configuration parameters including the refrigerant charge amount, the compressor displacement and the length of capillary tube were investigated. This study aims at providing deep insight into ejector-expansion technology applied in domestic refrigerator-freezers. - Highlights: • A NERC (novel ejector enhanced refrigeration cycle) was experimentally studied. • 73 experimental data points with different system configuration were acquired. • Energy consumption could be reduced with optimum system configuration. • 5.45% energy consumption reduction is obtained compared with the conventional system.

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.

HeREF-2003: Helium Refrigeration Techniques

CERN Multimedia

2003-01-01

CERN Technical Training 2003: Learning for the LHC ! Theory, Technology, Maintenance and Control of Helium Refrigerators HeREF-2003 is a course in the framework of the 2002 Technical Training Programme, that will provide a complete introduction to Helium refrigeration, with a practical approach to theory, technology, maintenance and control of Helium refrigeration installations. Theoretical aspects and equations will be limited to a minimum. HeREF-2003 targets an audience of technicians and operators of Helium refrigeration plants at CERN, as well as physicists and engineers needing an overview of current Helium refrigeration techniques. HeREF-2003 will address, among other, issues related to component technology, installation maintenance, process control and Helium purity. A commented visit to a couple of CERN Helium refrigeration or liquefaction plants will also take place. Duration: 7 half days (4 mornings and 3 afternoons), 6-10 October, 2003 Cost per participant: 500.- CHF Language: Bilingual English...

HeREF-2003 : Helium Refrigeration Techniques

CERN Multimedia

2003-01-01

CERN Technical Training 2003: Learning for the LHC ! Theory, Technology, Maintenance and Control of Helium Refrigerators HeREF-2003 is a course in the framework of the 2002 Technical Training Programme, that will provide a complete introduction to Helium refrigeration, with a practical approach to theory, technology, maintenance and control of Helium refrigeration installations. Theoretical aspects and equations will be limited to a minimum. HeREF-2003 targets an audience of technicians and operators of Helium refrigeration plants at CERN, as well as physicists and engineers needing an overview of current Helium refrigeration techniques. HeREF-2003 will address, among other, issues related to component technology, installation maintenance, process control and Helium purity. A commented visit to a couple of CERN Helium refrigeration or liquefaction plants will also take place. • Duration: 7 half days (4 mornings and 3 afternoons), 6-10 October, 2003 • Cost per participant: 500.- CHF
...

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

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.

49 CFR 173.174 - Refrigerating machines.

Science.gov (United States)

2010-10-01

... 49 Transportation 2 2010-10-01 2010-10-01 false Refrigerating machines. 173.174 Section 173.174 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS MATERIALS SAFETY... Refrigerating machines. A refrigerating machine assembled for shipment and containing 7 kg (15 pounds) or less...

Thermodynamic analysis of hydrocarbon refrigerants in a sub-cooling refrigeration system

Directory of Open Access Journals (Sweden)

BUKOLA O. BOLAJI

2013-06-01

Full Text Available In this study, the performance simulation of some hydrocarbon refrigerants (R290, R600 and R600a as alternatives to R134a in refrigeration system with sub-cooling is conducted by thermodynamic calculation of performance parameters using the REFPROP software. The results obtained showed that the saturated vapour pressure and temperature characteristic profiles for R600 and R600a are very close to that of R134a. The three hydrocarbon refrigerants exhibited very high refrigerating effect and condenser duty than R134a. The best of these parameters was obtained using R600. The discharge temperatures obtained using R600 and R600a were low, while that of R290 was very much higher. The highest coefficient of performance (COP and relative capacity index were obtained using R600. Average COPs of R600 and R600a are 4.6 and 2.2% higher than that of R134a, respectively. The performances of R600 and R600a in system were better than those of R134a and R290. The best performance was obtained using R600 in the system.

ARTI Refrigerant Database

Energy Technology Data Exchange (ETDEWEB)

Calm, J.M.

1992-11-09

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

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...

Thermoacoustic refrigerator for space applications

Science.gov (United States)

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

1993-10-01

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

A miniature adsorption3HE refrigerator

International Nuclear Information System (INIS)

Duband, L.; Ravex, A.; Lange, A.

1991-01-01

A self-contained, recyclable laboratory 3 He refrigerator has been developed. The refrigerator is very compact, portable and is designed to be safe and reliable. The unit can easily be installed on the cold plate of a superfluid 4 He cryostat. Once bolted on the cold plate, operation of the refrigerator is controlled by a single heater. In this new design the refrigerator has a cylindrical geometry. The adsorption pump is placed above the condensation point to prevent convection during the condensation phase and to improve the pumping speed. The inhibition of convection reduces the load on the 4 He bath and increases the condensation efficiency. This refrigeration technique has great potential for space applications. The absence of moving parts makes the system reliable and vibration free. Its simplicity and the absence of external components facilitate its integration on a cryostat. In fact, a rocket-borne 3 He refrigerator has already been successfully flown and has demonstrated the feasibility of this method

Not all counterclockwise thermodynamic cycles are refrigerators

Science.gov (United States)

Dickerson, R. H.; Mottmann, J.

2016-06-01

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

Cryogenic mixed refrigerant processes

CERN Document Server

Venkatarathnam, Gadhiraju

2010-01-01

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

Thermoacoustic engines and refrigerators

Energy Technology Data Exchange (ETDEWEB)

Swift, G.

1996-12-31

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

United States: refrigeration industry blows hot

International Nuclear Information System (INIS)

Crawford, J.

1997-01-01

In the framework of the Kyoto convention on global warming, the american refrigeration industries have undertaken several organizations and contacts with governments and agencies in order to explain the real issues concerning the effects of refrigerant utilization in refrigerating machines on the greenhouse effect, taking into consideration the commercial impact that a ban on certain refrigerants could have on the industry's business. They argue that HFC utilization in this industry is fundamentally non-emissive and that important improvements have been realized concerning tightness and energy consumption

Sorption compressor/mechanical expander hybrid refrigeration

Science.gov (United States)

Jones, J. A.; Britcliffe, M.

1987-01-01

Experience with Deep Space Network (DSN) ground-based cryogenic refrigerators has proved the reliability of the basic two-stage Gifford-McMahon helium refrigerator. A very long life cryogenic refrigeration system appears possible by combining this expansion system or a turbo expansion system with a hydride sorption compressor in place of the usual motor driven piston compressor. To test the feasibility of this system, a commercial Gifford-McMahon refrigerator was tested using hydrogen gas as the working fluid. Although no attempt was made to optimize the system for hydrogen operation, the refrigerator developed 1.3 W at 30 K and 6.6 W at 60 K. The results of the test and of theoretical performances of the hybrid compressor coupled to these expansion systems are presented.

Experimental installation of refrigeration solar-first results; Instalacion experimental de refrigeracion solar-primeros resultados

Energy Technology Data Exchange (ETDEWEB)

Moone, C.; Guallar, J.; Alonso, S.; Palacin, F.

2008-07-01

In this article they are and the first results of an installation of solar refrigeration composed by a field of flat solar collector are analysed and absorption chillers of simple effect (BrLi-H{sub 2}O), used to give cold to a gymnasium of the university sport pavilion. The data correspond to the registered experimental values during the summer of 2007 (months of June, Julio and August). (Author)

46 CFR 154.702 - Refrigerated carriage.

Science.gov (United States)

2010-10-01

... Pressure and Temperature Control § 154.702 Refrigerated carriage. (a) Each refrigeration system must: (1) Have enough capacity to maintain the cargo vapor pressure in each cargo tank served by the system below... the purpose of this section, a “refrigeration unit” includes a compressor and its motors and controls...

Solar Refrigerators Store Life-Saving Vaccines

Science.gov (United States)

2014-01-01

Former Johnson Space Center engineer David Bergeron used his experience on the Advanced Refrigeration Technology Team to found SunDanzer Refrigeration Inc., a company specializing in solar-powered refrigerators. The company has created a battery-free unit that provides safe storage for vaccines in rural and remote areas around the world.

Anomalous water absorption in porous materials

CERN Document Server

Lockington, D A

2003-01-01

The absorption of fluid by unsaturated, rigid porous materials may be characterized by the sorptivity. This is a simple parameter to determine and is increasingly being used as a measure of a material's resistance to exposure to fluids (especially moisture and reactive solutes) in aggressive environments. The complete isothermal absorption process is described by a nonlinear diffusion equation, with the hydraulic diffusivity being a strongly nonlinear function of the degree of saturation of the material. This diffusivity can be estimated from the sorptivity test. In a typical test the cumulative absorption is proportional to the square root of time. However, a number of researchers have observed deviation from this behaviour when the infiltrating fluid is water and there is some potential for chemo-mechanical interaction with the material. In that case the current interpretation of the test and estimation of the hydraulic diffusivity is no longer appropriate. Kuentz and Lavallee (2001) discuss the anomalous b...

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.

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.

The greatest solar refrigeration plant of Switzerland. Holistic saving of CO{sub 2} at a private bank; Die groesste solare Kaelteanlage der Schweiz. Ganzheitliche CO{sub 2}-Einsparung bei einer Privatbank

Energy Technology Data Exchange (ETDEWEB)

Schmid, Wolfgang

2011-07-01

Since June 2008, the Swiss private bank Pictet and Cie. (Geneva, Switzerland) operates the largest solar refrigerant plant of Switzerland. The solar generated heat is used all over the year for heating up of drinking water, seasonally for room air conditioning and in the summer for driving of three absorption refrigerators with a refrigerating capacity of totally 210 kW. This is sufficient in order to keep the office space of nearly 4,000 m{sup 2} at a moderate temperature by means of cooling ceilings.

ITER TASK T26/28 (1995): Solubility, diffusion and absorption of hydrogen isotopes in potential fusion reactor ceramics

International Nuclear Information System (INIS)

Thompson, D.A.; Macauley-Newcombe, R.G.

1996-04-01

Ceramic insulators are integral parts of numerous components essential for the heating control and diagnostic measurement of fusion plasmas. For safe and reliable reactor operations it is necessary to be able to predict the resultant tritium inventories and permeation fluxes through these materials. Some materials being considered are Al 2 O 3 (both as single crystal sapphire and polycrystalline alumina) and BeO. This report contains results of ion-implantation, thermal absorption (diffusion loading) and ion-beam analysis experiments performed in 1994 and 1995 for ITER task T26/28. The combination of implantation and thermal absorption capabilities enable us to load samples with hydrogen isotopes under differing conditions. 13 figs., 1 tab., 11 refs

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.

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

Suitability criterion for a refrigerant for use in solar operated sorption refrigerator

International Nuclear Information System (INIS)

Tabassum, S.A.; Mir, M.S.

1996-01-01

The thermodynamics of a sorption refrigeration cycle has been discussed representing the cycle on a clapeyron digram. The minimum generation temperature required has been determined using the 'd-a' equation which represents the sorption equilibrium of the pair, and Gibbs free energy relation. The mathematical relation developed provides a totally new basis for determination of suitability of a particular refrigerant. (author)

Suitability criterion for a refrigerant for use in solar operated sorption refrigerator

Energy Technology Data Exchange (ETDEWEB)

Tabassum, S A; Mir, M S [University of Engineering and Technology, Lahore (Pakistan). Dept. of Mechanical Engineering

1996-06-01

The thermodynamics of a sorption refrigeration cycle has been discussed representing the cycle on a clapeyron digram. The minimum generation temperature required has been determined using the `d-a` equation which represents the sorption equilibrium of the pair, and Gibbs free energy relation. The mathematical relation developed provides a totally new basis for determination of suitability of a particular refrigerant. (author).

Use of x-ray absorption imaging to evaluate the effects of heterogeneity on matrix diffusion

International Nuclear Information System (INIS)

Altman, S.J.; Tidwell, V.C.; McKenna, S.A.; Meigs, L.C.

1998-01-01

An understanding of matrix diffusion is important in assessing potential nuclear waste repositories in geologic media, as it is a potentially significant process in retarding the transport of contaminant species. Recent work done in evaluating the Waste Isolation Pilot Plant (WIPP) in southeastern New Mexico has brought up two issues that complicate the incorporation of diffusion in Performance Assessment calculations. First, interpretations of single-well tracer test data suggest that the tracer was diffusing at multiple rates. Second, the estimated relevant rate(s) of diffusion are dependent on the time and length scales of the problem. To match the observed tracer test data, a model with a distribution of diffusion coefficients was required. This has led to the proposal of applying a model with multiple rates of diffusion, the multirate model, to Performance Assessment calculations for the WIPP. A series of laboratory- scale experiments have been designed for the purpose of evaluating heterogeneity and scaling properties of diffusion rates and to test the multirate model. X-ray absorption imaging was used to visualize and quantify the effects of matrix heterogeneity on the diffusion characteristics for four different centimeter-scale samples of dolomite. The samples were obtained from the Culebra dolomite at the WIPP site. Significant variations in diffusion rates were observed over relatively small length and time (months) scales for the preliminary laboratory experiments. A strong correlation between diffusion rate and porosity was also observed in each of the samples. Two sets of experiments are planned for 1998. The first set of experiments is similar to those described above. For these experiments, fourteen samples exhibiting a broader range of physical characteristics are being tested. The second set of experiments will visualize the combined effect of advection in a fracture and diffusion into adjacent matrix materials. Tracer solution will flow through

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

Science.gov (United States)

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

Polyhalogenated hydrocarbon refrigerants and refrigerant oils colored with fluorescent dyes and method for their use as leak detectors

Energy Technology Data Exchange (ETDEWEB)

Parekh, M.

1988-07-19

A leak detectable refrigeration composition is described comprising: (A) a refrigeration liquid selection from the group consisting of: (1) a polyhalogenated hydrocarbon refrigerant; (2) a refrigeration oil selected from the group consisting of naphthenic oils, paraffinic oils, alkylated benzenes, silicones, polyglycols, diesters or triesters of dicarboxylic or tricarboxylic acids, and polyalkyl silicate oils, and (3) a mixture of A(1) and A(2), and (B) a fluorescent dye compound or composition comprising the dye selected from the group consisting of: (1) a fluorescent dye selected from the group consisting of perylene, naphthoxanthene, monocyclic aromatic compounds having an organometallic compound, (2) a solution of fluorescent dye in a solvent, and (3) a mixture of B(1) and B(2). The fluorescent dye compound or composition is soluble in the refrigeration liquid. The concentration of the dye being at least 0.001 grams per 100 grams of the refrigeration liquid.

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

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.

Evaluation of absorbents for an absorption heat pump using natural organic working fluids (eco-energy city project)

Energy Technology Data Exchange (ETDEWEB)

Hisajima, Daisuke; Sakiyama, Ryoko; Nishiguchi, Akira [Hitachi Ltd., Tsuchiura (Japan). Mechanical Engineering Research Lab.

1999-07-01

The present situation of electric power supply and energy consumption in Japan has made it necessary to develop a new absorption air conditioning system which has low electric energy consumption, uses natural organic refrigerants, and can work as a heat pump in winter. Estimating vapor and liquid equilibrium of new pairs of working fluids is prerequisite to developing the new absorption heat pump system. In this phase of the work, methods for estimating vapor and liquid equilibrium that take into account intermolecular force were investigated. Experimental and calculated data on natural organic materials mixtures were considered to find optimum candidates, and then a procedure for evaluation was chosen. Several candidate absorbents were selected that used isobutane and dimethyl ether as refrigerants. (orig.)

Refrigeration: Introducing energy saving opportunities for business

Energy Technology Data Exchange (ETDEWEB)

NONE

2006-04-15

In some industries, most notably food and drink and chemicals, refrigeration accounts for a significant proportion of overall site energy costs. For instance, in the industrial handling of meat, poultry and fish, it often accounts for 50% of total energy costs. In ice-cream production the proportion is 70%. In a number of commercial sectors, refrigeration also represents a significant proportion of overall energy costs. For example: Cold storage 90%; Food supermarkets 50%; Small shops with refrigerated cabinets 70% or over; Pubs and clubs 30%. Against these high costs, even a small reduction in refrigeration energy use can offer significant cost savings, resulting in increased profits. Energy saving need not be expensive. Energy savings of up to 20% can be realised in many refrigeration plant through actions that require little or no investment. In addition, improving the efficiency and reducing the load on a refrigeration plant can improve reliability and reduce the likelihood of a breakdown. Most organisations can save energy and money on refrigeration by: More efficient equipment; Good maintenance; Housekeeping and control. This publication provides an understanding of the operation of refrigeration systems, identifies where savings can be realised and will enable readers to present an informed case on energy savings to key decision makers within their organisation. (GB)

Environmentally benign working pairs for adsorption refrigeration

International Nuclear Information System (INIS)

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

2005-01-01

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

Thermodynamic modelling and parametric study of a low temperature vapour compression-absorption system based on modified Gouy-Stodola equation

International Nuclear Information System (INIS)

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

2015-01-01

Present paper thermodynamically analyses a VCAS (vapour compression-absorption system) with carbon dioxide (compression section) and ammonia-water (absorption section) as refrigerants and determines the optimal condensing temperature of cascade condenser using modified Gouy-Stodola equation. The optimum cascade condenser temperature is found to be −13 °C for 175 kW refrigeration capacity at an evaporator temperature of −45 °C and condenser temperature of 35 °C. The optimum cascade condenser temperature maximises the overall COP, rational efficiency and minimises the total irreversibility rate of the VCAS system. The value of optimum condensing temperature and its corresponding maximum COP, and minimum irreversibility rate are discussed for a wide range of operating conditions. Further, a comparative study of TSVCS (two stage vapour compression system) used for low temperature refrigeration applications with VCAS shows that at design point, primary energy consumption is reduced by 60.6% and electrical COP is improved by 153.6% in VCAS as compared to conventional TSVCS. But the total irreversibility rate of VCAS is 38.4% higher than the TSVCS due to the use of low grade energy in vapour absorption system and hence the rational efficiency of VCAS is 14% low. - Highlights: • Optimum cascade condenser temperature with modified Gouy-Stodola law is analysed. • It maximises COP, rational efficiency and minimises total irreversibility. • 60.6% of primary energy is saved by cascaded absorption system. • Electrical COP is improved by 153.6% with cascaded absorption system

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

Science.gov (United States)

Carey, John

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

2014 German refrigeration and air conditioning meeting. Proceedings

International Nuclear Information System (INIS)

2014-01-01

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

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

Performance characteristics of a quantum Diesel refrigeration cycle

International Nuclear Information System (INIS)

He Jizhou; Wang Hao; Liu Sanqiu

2009-01-01

The Diesel refrigeration cycle using an ideal quantum gas as the working substance is called quantum Diesel refrigeration cycle, which is different from Carnot, Ericsson, Brayton, Otto and Stirling refrigeration cycles. For ideal quantum gases, a corrected equation of state, which considers the quantum behavior of gas particles, is used instead of the classical one. The purpose of this paper is to investigate the effect of quantum gas as the working substance on the performance of a quantum Diesel refrigeration cycle. It is found that coefficients of performance of the cycle are not affected by the quantum degeneracy of the working substance, which is the same as that of the classical Diesel refrigeration cycle. However, the refrigeration load is different from those of the classical Diesel refrigeration cycle. Lastly, the influence of the quantum degeneracy on the performance characteristics of the quantum Diesel refrigeration cycle operated in different temperature regions is discussed

Cogeneration with gas turbine associated to the absorption refrigeration system: a computer program for exergy economics analysis; Cogeracao com turbina a gas associada ao sistema de refrigeracao por absorcao: um programa computacional para analise exergoeconomica

Energy Technology Data Exchange (ETDEWEB)

Antunes, Julio Santana [UNESP, Guaratingueta, SP (Brazil). Faculdade de Engenharia. Dept. de Matematica] E-mail: santana@feg.unesp.br; Silveira, Jose Luz; Balestieri, Jose Antonio Perrella [UNESP, Guaratingueta, SP (Brazil). Faculdade de Engenharia. Dept. de Energia

2000-07-01

This paper presents the development of a computer program for exergy and economic analysis of cogeneration systems applying gas turbine associated to the absorption refrigeration system. The computer program selects gas turbine systems viewing the operation under thermal parity through a data base composed by gas turbines commercially available in the market, under the ISO (International Standard Organization). The computer program corrects the system performance parameters selected for the installation local conditions. The exergy and economic analysis are made based on the lowest exergy manufacturing cost where the best system is considered. A case study of the computer program application is presented.

ARTI refrigerant database. Quarterly report, March--May 1997

Energy Technology Data Exchange (ETDEWEB)

Calm, J.M.

1997-05-01

The Refrigerant Database is an information system on alternative refrigerants, associated lubricants, and their use in air conditioning and refrigeration. It consolidates and facilitates access to property, compatibility, environmental, safety, application and other information. It provides corresponding information an older refrigerants, to assist manufacturers and those using alternative refrigerants, to make comparisons and determine differences. The underlying purpose is to accelerate phase out of chemical compounds of environmental concern. The database provides bibliographic citations and abstracts for publications that may be useful in research and design of air-conditioning and refrigeration equipment. The complete documents are not included, though some may be added at a later date.

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...

Lévy flight with absorption: A model for diffusing diffusivity with long tails

Science.gov (United States)

Jain, Rohit; Sebastian, K. L.

2017-03-01

We consider diffusion of a particle in rearranging environment, so that the diffusivity of the particle is a stochastic function of time. In our previous model of "diffusing diffusivity" [Jain and Sebastian, J. Phys. Chem. B 120, 3988 (2016), 10.1021/acs.jpcb.6b01527], it was shown that the mean square displacement of particle remains Fickian, i.e., ∝T at all times, but the probability distribution of particle displacement is not Gaussian at all times. It is exponential at short times and crosses over to become Gaussian only in a large time limit in the case where the distribution of D in that model has a steady state limit which is exponential, i.e., πe(D ) ˜e-D /D0 . In the present study, we model the diffusivity of a particle as a Lévy flight process so that D has a power-law tailed distribution, viz., πe(D ) ˜D-1 -α with 0 <α <1 . We find that in the short time limit, the width of displacement distribution is proportional to √{T }, implying that the diffusion is Fickian. But for long times, the width is proportional to T1 /2 α which is a characteristic of anomalous diffusion. The distribution function for the displacement of the particle is found to be a symmetric stable distribution with a stability index 2 α which preserves its shape at all times.

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

Energy Technology Data Exchange (ETDEWEB)

Koyama, Shigeru; Yu, Jian; Ishibashi, Akira

1999-07-01

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

Compatibility of refrigerants and lubricants with elastomers

Energy Technology Data Exchange (ETDEWEB)

Hamed, G.R.; Seiple, R.H.

1993-01-01

The information contained in this report is designed to assist the air-conditioning and refrigeration industry in the selection of suitable elastomeric gasket and seal materials that will prove useful in various refrigerant and refrigeration lubricant environments. 97% of the swell measurements have been made to date. The other 3% of the measurements are contingent on availability of additional R-32. Swell behavior in the fluids have been determined using weight and in situ diameter measurements for the refrigerants and weight, diameter and thickness measurements for the lubricants. Weight and diameter measurements are repeated after 2 and 24 hours for samples removed from the refrigerant test fluids and 24 hours after removal from the lubricants.

2017 German refrigeration and air conditioning meeting. Proceedings; Deutsche Kaelte- und Klimatagung 2017. Tagungsbericht

Energy Technology Data Exchange (ETDEWEB)

NONE

2017-07-01

This year's lecture programme includes 117 presentations in the five working departments of DKV and 10 lectures at the special event ''Energy-efficient air conditioning in data centres''. The main topics in the respective departments were: (1) Cryogenics: Space applications; Cryogenic plants; Cryomedicine and cryobiology; Components, developments; Processes and plants; Valves, design. (2) Basics: Evaporation, material values; evaporation, condensation; absorption; adsorption, latent storage; cycle simulation. (3) Components: CO{sub 2} plant engineering and components; refrigerants; process control, adsorption, sublimation and storage technology; refrigerating machine oils, heat exchangers and corrosion; components 4.0, sensors and control technology; simulation of plant processes. (4) Cold application: Application; Application / Natural Refrigerants; Mobile Applications Car; Mobile Applications; Supermarket / Efficiency; Optimization / Efficiency. (5) Air conditioning and heat pump applications: load shifting, smart home, flexibility; heat sources and industrial heat pumps; modelling, simulations; energy concepts heat pumps and photovoltaics; monitoring, evaluation; technology trends / working materials. Six papers are separately analyzed for this database. [German] Das Vortragsprogramm umfasst in diesem Jahr 117 Beitraege in den fuenf Arbeitsabteilungen des DKV und 10 Vortraege in der Sonderveranstaltung ''Energieeffiziente Klimatisierung in Rechenzentren''. Die Hauptthemen in den jeweiligen Arbeitsabteilungen waren: (1) Kryotechnik: Raumfahrtanwendungen; Kryo-Grossanlagen; Kryomedizin und Kryobiologie; Komponenten, Entwicklungen; Verfahren und Anlagen; Ventile, Auslegung. (2) Grundlagen: Verdampfung, Stoffwerte; Verdampfung, Kondensation; Absorption; Adsorption, Latentspeicher; Kreislaufsimulation. (3) Komponenten: CO{sub 2}-Anlagentechnik und Komponenten; Kaeltemittel; Prozessfuehrung, Adsorption, Sublimation und

Eternal solutions to a singular diffusion equation with critical gradient absorption

International Nuclear Information System (INIS)

Iagar, Razvan Gabriel; Laurençot, Philippe

2013-01-01

The existence of non-negative radially symmetric eternal solutions of exponential self-similar type u(t, x) = e −pβt/(2−p) f β (|x|e −βt ; β) is investigated for the singular diffusion equation with critical gradient absorption ∂ t u−Δ p u+|∇u| p/2 =0  in (0,∞)×R N , where 2N/(N + 1) < p < 2. Such solutions are shown to exist only if the parameter β ranges in a bounded interval (0, β * ], which is in sharp contrast to well-known singular diffusion equations, such as ∂ t φ − Δ p φ = 0 when p = 2N/(N + 1), N ⩾ 1, or the porous medium equation ∂ t φ − Δφ m  = 0 when m = (N − 2)/N, N ⩾ 3. Moreover, the profile f(r; β) decays to zero as r → ∞ in a faster way for β = β * than for β ∈ (0, β * ) but the algebraic leading order is the same in both cases. In fact, for large r, f(r; β * ) decays as r −p/(2−p) while f(r; β) behaves as (log r) 2/(2−p) r −p/(2−p) when β ∈ (0, β * ). (paper)

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

Refrigerating liquid prototype for LED's thermal management

International Nuclear Information System (INIS)

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

2012-01-01

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

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

Energy optimisation of domestic refrigerators

DEFF Research Database (Denmark)

Jakobsen, Arne; Rasmussen, Bjarne D.

1998-01-01

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

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.

Manufacturing A Refrigerator with Heat Recovery Unit

Directory of Open Access Journals (Sweden)

Mustafa Mohammed Kadhim

2018-02-01

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

HFC perspectives in air-conditioning and refrigeration; Perspectives HFC en A/C et refrigeration

Energy Technology Data Exchange (ETDEWEB)

Fauvarque, P [ELF Atochem, Centre d` Application de Lavallois, 92 (France)

1998-12-31

This paper is a series of transparencies dealing with the development of substitutes for the replacement of the R-22 refrigerant in air-conditioning systems (R-134a, R-407C, R-410A), and in industrial refrigeration systems of agriculture and food industry (R-134a and R-404A). (J.S.)

HFC perspectives in air-conditioning and refrigeration; Perspectives HFC en A/C et refrigeration

Energy Technology Data Exchange (ETDEWEB)

Fauvarque, P. [ELF Atochem, Centre d`Application de Lavallois, 92 (France)

1997-12-31

This paper is a series of transparencies dealing with the development of substitutes for the replacement of the R-22 refrigerant in air-conditioning systems (R-134a, R-407C, R-410A), and in industrial refrigeration systems of agriculture and food industry (R-134a and R-404A). (J.S.)

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

Ex vivo and in vivo diffusion of ropivacaine through spinal meninges: influence of absorption enhancers.

Science.gov (United States)

Brandhonneur, Nolwenn; Dollo, Gilles; Ratajczak-Enselme, Maja; Deniau, Anne Laure; Chevanne, François; Estèbe, Jean Pierre; Legrand, Alain; Le Corre, Pascal

2011-02-14

Following epidural administration, cerebrospinal fluid bioavailability of local anesthetics is low, one major limiting factor being diffusion across the arachnoid mater barrier. The aim of this study was to evaluate the influence of absorption enhancers on the meningeal permeability of epidurally administered ropivacaine. Five enhancers known for their ability to increase drug permeability via transcellular and/or paracellular pathways, i.e. palmitoyl carnitine, ethylenediaminetetraacetic acid, sodium caprate, dodecylphosphocholine and pentylglycerol, were tested ex vivo on fresh specimen of meninges removed from cervical to lumbar level of rabbit spine following laminectomy and placed in diffusion chambers. Among them, sodium caprate lead to the best permeability improvement for both marker and drug (440% and 112% for mannitol and ropivacaine, respectively) and was therefore selected for in vivo study in a sheep model using microdialysis technique to evaluate epidural and intrathecal ropivacaine concentrations following epidural administration. Resulting dialysate and plasma concentrations were used to calculate pharmacokinetic parameters. Following sodium caprate pre-treatment, ropivacaine intrathecal maximal concentration (Cmax) was 1.6 times higher (78 ± 16 μg ml(-1) vs 129 ± 26 μg ml(-1), p<0.05) but the influence of the absorption enhancer was only effective the first 30 min following ropivacaine injection, as seen with the significantly increase of intrathecal AUC(0-30 min) (1629 ± 437 μg min ml(-1) vs 2477 ± 559 μg min ml(-1), p<0.05) resulting in a bioavailable fraction 130% higher 30 min after ropivavaine administration. Co-administration of local anesthetics with sodium caprate seems to allow a transient and reversible improvement of transmeningeal passage into intrathecal space. Copyright © 2010 Elsevier B.V. All rights reserved.

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%

New magnetic refrigeration materials for the liquefaction of hydrogen

International Nuclear Information System (INIS)

Gschneidner, K.A.; Takeya, H.; Moorman, J.O.; Pecharsky, V.K.; Malik, S.K.; Zimm, C.B.

1994-01-01

Five heavy lanthanide ferromagnetic intermetallic compounds were studied as potential magnetic refrigerants for the liquefaction of hydrogen gas. (Dy 0.5 Er 0.5 )Al 2 and TbNi 2 appear to be better refrigerants than GdPd for a Joule-Brayton cycle refrigerator, while (Gd 0.54 Er 0.46 )AlNi seems to be a suitable refrigerant for an Ericsson cycle refrigerator

Reasearch and Evaluation of Electromagnetic Fields of Refrigerators

Directory of Open Access Journals (Sweden)

Pranas Baltrėnas

2013-12-01

Full Text Available The use of refrigerators causes the occurence of electromagnetic fields that are invisible and intangible, which therefore makes difficulties in protecting ourselves from them. A refrigerator is an irreplaceable item in domestic household and thus can be hardly ignored by a modern way of human life. In order to preserve the characteristics of products, the refrigerator must operate continuously (24 hrs a day, regardless of the time of the year. This results in a huge increase in electricity consumption, which leads to energy consumption related pollution of the environment emitting CO2 gas. On these grounds, it is necessary to assess electromagnetic fields created by the refrigerator. Studies on electromagnetic fields produced by refrigerators were conducted in domestic premises where people spent a significant part of the day. For comparison purposes, five different power refrigerators were chosen (1 – 0.20 kW; 2 – 0.25 kW; 3 – 0.30 kW; 4 – 0.35 kW; 5 – 0.40 kW. The obtained results, according to the parameters of their electromagnetic fields, were presented in graphs and charts and showed that the values of electric and magnetic intensity of refrigerators depended on the distance and the power of the refrigerator. The conducted research also disclosed that none of tested refrigerators exceeded the permissible limits of electromagnetic fields.Article in Lithuanian

Krypton based adsorption type cryogenic refrigerator

Science.gov (United States)

Jones, Jack A. (Inventor); Schember, Helene R. (Inventor)

1989-01-01

Krypton and a monolithic porous carbon such as Saran carbon are used respectively as the sorbate and sorbent of an adsorption type refrigerator to improve refrigeration efficiency and operational longevity.

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

46 CFR 147.90 - Refrigerants.

Science.gov (United States)

2010-10-01

.../ASHRAE 34-78 may be carried as ships' stores. (b) Refrigerants contained in a vessel's operating system... 46 Shipping 5 2010-10-01 2010-10-01 false Refrigerants. 147.90 Section 147.90 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) DANGEROUS CARGOES HAZARDOUS SHIPS' STORES Stowage and Other...

Absorption heat pump for space applications

Science.gov (United States)

Nguyen, Tuan; Simon, William E.; Warrier, Gopinath R.; Woramontri, Woranun

1993-01-01

In the first part, the performance of the Absorption Heat Pump (AHP) with water-sulfuric acid and water-magnesium chloride as two new refrigerant-absorbent fluid pairs was investigated. A model was proposed for the analysis of the new working pairs in a heat pump system, subject to different temperature lifts. Computer codes were developed to calculate the Coefficient of Performance (COP) of the system with the thermodynamic properties of the working fluids obtained from the literature. The study shows the potential of water-sulfuric acid as a satisfactory replacement for water-lithium bromide in the targeted temperature range. The performance of the AHP using water-magnesium chloride as refrigerant-absorbent pair does not compare well with those obtained using water-lithium bromide. The second part concentrated on the design and testing of a simple ElectroHydrodynamic (EHD) Pump. A theoretical design model based on continuum electromechanics was analyzed to predict the performance characteristics of the EHD pump to circulate the fluid in the absorption heat pump. A numerical method of solving the governing equations was established to predict the velocity profile, pressure - flow rate relationship and efficiency of the pump. The predicted operational characteristics of the EHD pump is comparable to that of turbomachinery hardware; however, the overall efficiency of the electromagnetic pump is much lower. An experimental investigation to verify the numerical results was conducted. The pressure - flow rate performance characteristics and overall efficiency of the pump obtained experimentally agree well with the theoretical model.

The limitation and modification of flux-limited diffusion theory

International Nuclear Information System (INIS)

Liu Chengan; Huang Wenkai

1986-01-01

The limitation of various typical flux-limited diffusion theory and advantages of asymptotic diffusion theory with time absorption constant are analyzed and compared. The conclusions are as following: Though the flux-limited problem in neutron diffusion theory are theoretically solved by derived flux-limited diffusion equation, it's going too far to limit flux due to the inappropriate assumption in deriving flux-limited diffusion equation. The asymptotic diffusion theory with time absorption constant has eliminated the above-mentioned limitation, and it is more accurate than flux-limited diffusion theory in describing neutron transport problem

46 CFR 111.79-15 - Receptacles for refrigerated containers.

Science.gov (United States)

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Receptacles for refrigerated containers. 111.79-15... ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Receptacles § 111.79-15 Receptacles for refrigerated containers. Receptacles for refrigerated containers must meet one of the following: (a) Each receptacle for refrigerated...

THE STIRLING GAS REFRIGERATING MACHINE MECHANICAL DESIGN IMPROVING

Directory of Open Access Journals (Sweden)

V. V. Trandafilov

2016-06-01

Full Text Available To improve the mechanical design of the piston Stirling gas refrigeration machine the structural optimization of rotary vane Stirling gas refrigeration machine is carried out. This paper presents the results of theoretical research. Analysis and prospects of rotary vane Stirling gas refrigeration machine for domestic and industrial refrigeration purpose are represented. The results of a patent search by mechanisms of transformation of rotary vane machines are discussed.

THE STIRLING GAS REFRIGERATING MACHINE MECHANICAL DESIGN IMPROVING

Directory of Open Access Journals (Sweden)

V. V. Trandafilov

2016-02-01

Full Text Available To improve the mechanical design of the piston Stirling gas refrigeration machine the structural optimization of rotary vane Stirling gas refrigeration machine is carried out. This paper presents the results of theoretical research. Analysis and prospects of rotary vane Stirling gas refrigeration machine for domestic and industrial refrigeration purpose are represented. The results of a patent search by mechanisms of transformation of rotary vane machines are discussed

Absorption of water and lubricating oils into porous nylon

Science.gov (United States)

Bertrand, P. A.

1995-01-01

Oil and water absorption from air into sintered porous nylon can be described by infiltration into the pores of the material. This process can be modeled by a diffusion-like mechanism. For water absorption, we find a formal diffusion coefficient of 1.5 x 10(exp -4)sq cm/min when the nylon is initially dry. The diffusion coefficient is 4 x 10(exp -6)sq cm/min when the nylon is oil-impregnated prior to air exposure. In a 52% RH atmosphere, dry nylon absorbs 3% w/w water, and oil-impregnated nylon absorbs 0.6% w/w water. For oil absorption there are three steps: (1) surface absorption and infiltration into (2) larger and (3) smaller pores. Surface absorption is too fast to be measured in these experiments. The diffusion coefficient for the second step is 6 x 10(exp -4)sq cm/min for SRG-60 oil into dry nylon and 4 x 10(exp -4)sq cm/min for air-equilibrated nylon. The diffusion coefficient for the third step is about 1 x 10(exp -6)sq cm/min for both cases. The total amount of oil absorbed is 31% w/w. The interaction between water and nylon is not as strong as that between water and cotton-phenolic: oil can replace water, and only a small amount of water can enter previously oil-impregnated nylon.

Simulated performance of biomass gasification based combined power and refrigeration plant for community scale application

Energy Technology Data Exchange (ETDEWEB)

Chattopadhyay, S., E-mail: suman.mech09@gmail.com [Department of Mechanical Engineering, NIT, Agarpara, Kolkata – 700109, West Bengal (India); Mondal, P., E-mail: mondal.pradip87@gmail.com; Ghosh, S., E-mail: sudipghosh.becollege@gmail.com [Department of Mechanical Engineering, IIEST, Shibpur, Howrah – 711103, West Bengal (India)

2016-07-12

Thermal performance analysis and sizing of a biomass gasification based combined power and refrigeration plant (CPR) is reported in this study. The plant is capable of producing 100 kWe of electrical output while simultaneously producing a refrigeration effect, varying from 28-68 ton of refrigeration (TR). The topping gas turbine cycle is an indirectly heated all-air cycle. A combustor heat exchanger duplex (CHX) unit burns producer gas and transfer heat to air. This arrangement avoids complex gas cleaning requirements for the biomass-derived producer gas. The exhaust air of the topping GT is utilized to run a bottoming ammonia absorption refrigeration (AAR) cycle via a heat recovery steam generator (HRSG), steam produced in the HRSG supplying heat to the generator of the refrigeration cycle. Effects of major operating parameters like topping cycle pressure ratio (r{sub p}) and turbine inlet temperature (TIT) on the energetic performance of the plant are studied. Energetic performance of the plant is evaluated via energy efficiency, required biomass consumption and fuel energy savings ratio (FESR). The FESR calculation method is significant for indicating the savings in fuel of a combined power and process heat plant instead of separate plants for power and process heat. The study reveals that, topping cycle attains maximum power efficiency of 30%in pressure ratio range of 8-10. Up to a certain value of pressure ratio the required air flow rate through the GT unit decreases with increase in pressure ratio and then increases with further increase in pressure ratio. The capacity of refrigeration of the AAR unit initially decreases up to a certain value of topping GT cycle pressure ratio and then increases with further increase in pressure ratio. The FESR is found to be maximized at a pressure ratio of 9 (when TIT=1100°C), the maximum value being 53%. The FESR is higher for higher TIT. The heat exchanger sizing is also influenced by the topping cycle pressure ratio

Adsorption refrigeration technology theory and application

CERN Document Server

Wang, Ruzhu; Wu, Jingyi

2014-01-01

Gives readers a detailed understanding of adsorption refrigeration technology, with a focus on practical applications and environmental concerns Systematically covering the technology of adsorption refrigeration, this book provides readers with a technical understanding of the topic as well as detailed information on the state-of-the-art from leading researchers in the field. Introducing readers to background on the development of adsorption refrigeration, the authors also cover the development of adsorbents, various thermodynamic theories, the design of adsorption systems and adsorption refri

Refrigerated display cabinets; Butikskyla

Energy Technology Data Exchange (ETDEWEB)

Fahlen, Per

2000-07-01

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

Analysis of cooldown performance for Isabelle helium refrigerator

International Nuclear Information System (INIS)

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

1982-01-01

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

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.

On uniqueness in diffuse optical tomography

International Nuclear Information System (INIS)

Harrach, Bastian

2009-01-01

A prominent result of Arridge and Lionheart (1998 Opt. Lett. 23 882–4) demonstrates that it is in general not possible to simultaneously recover both the diffusion (aka scattering) and the absorption coefficient in steady-state (dc) diffusion-based optical tomography. In this work we show that it suffices to restrict ourselves to piecewise constant diffusion and piecewise analytic absorption coefficients to regain uniqueness. Under this condition both parameters can simultaneously be determined from complete measurement data on an arbitrarily small part of the boundary

Theoretical study of electronic absorption spectroscopy of propadienylidene molecule vis-â-vis the observed diffuse interstellar bands

International Nuclear Information System (INIS)

Reddy, Samala Nagaprasad; Mahapatra, S.

2012-01-01

Highlights: ► Theoretical study of spectroscopy and dynamics of electronically excited l-C 3 H 2 . ► Construction of ab initio electronic potential energy and diabatic coupling surfaces. ► First principles study of nuclear dynamics on excited electronic states. ► Findings reveal l-C 3 H 2 is a potential molecular carrier of diffuse interstellar bands. ► Electronically excited l-C 3 H 2 decays by ultrafast nonradiative internal conversion. -- Abstract: Observation of broad and diffuse interstellar bands (DIBs) at 4881 Å and 5440 Å assigned to the optical absorption spectrum of Y-shaped propadienylidene (H 2 C=C=C:) molecule is theoretically examined in this paper. This molecule apparently absorbs in the same wavelength region as the observed DIBs and was suggested to be a potential carrier of these DIBs. This assignment mostly relied on the experimental data from radioastronomy and laboratory measurements. Motivated by these available experimental data we attempt here a theoretical study and investigate the detailed electronic structure and nuclear dynamics underlying the electronic absorption bands of propadienylidene molecule. Our results show that this molecule indeed absorbs in the wavelength region of the recorded DIBs. Strong nonadiabatic coupling between its energetically low-lying electronic states plays major role, initiates ultrafast internal conversion and contributes to the spectral broadening. Theoretical findings are finally compared with the available experimental and theoretical data and discussed in connection with the recorded DIBs.

2011 German refrigeration and air conditioning meeting. Proceedings; Deutsche Kaelte-Klima-Tagung 2011. Tagungsbericht

Energy Technology Data Exchange (ETDEWEB)

NONE

2011-07-01

Within the DKV conference of the Deutscher Kaelte- und Klimatechnischer Verein e.V. (Hanover, Federal Republic of Germany) from 16th to 18th November, 2011, at the Eurogress Aachen (Federal Republic of Germany) 112 lectures were held according to the following themes: cryomedicine, cryobiology, cryocomponents, mobility, cryoapplications, miniature cooler, Fundamentals and materials in the cryotechnology and heat pump technology, heat transfer, absorption processes, materials characteristics and phase change materials, storage and phase change, plants and components of refrigerating and heat pump technology - compressors, control and systems, energy efficiency (and CO{sub 2}), standardization and standard, application of refrigeration, supermarket/coolant, enhancement of efficiency in the air conditioning of passenger cars, indoor air conditioning in automobiles, enhancement of efficiency in different vehicles, climate technology and application of heat pumps - field tests and optimization, test rigs and simulations, heat pumps, optimisation in new buildings and stock buildings, climate coolants and quality of air. Beside this conference twelve student meetings were presented.

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

The disappearance of HCFC 22 and the search for the ideal refrigerant; La disparition du HCFC-22 et le recherche du refrigerant ideal

Energy Technology Data Exchange (ETDEWEB)

Dumas, C. [Ville de Montreal, PQ (Canada). Direction des Immeubles Gestion de l' Energie et du Genie Climatique

2003-03-01

The City of Montreal, Quebec is searching for the optimum refrigerant, and has determined that ammonia, carbon dioxide, hydrocarbons and refrigerant-mixes in the 400 series are to be considered for general refrigeration and in skating rinks in the next years. The refrigerants of the 400 series contribute to the greenhouse effect and it is not possible to utilize them in sunk type systems. The City of Montreal has 12 per cent of ice surfaces in Quebec. The Montreal Protocol, a United Nations document calls for the gradual elimination of the refrigerant monochlorodifluoromethane (HCFC 22) starting in 2004 and that none will be made after 2020 in order to protect the ozone layer. In this document, the author discussed the following topics: (1) supply problems, regulations, international index used to compare refrigeration systems, (2) the origin of refrigerants available on the market and why the chemical industry is incapable of producing the miracle refrigerant, and (3) a proposal for an action plan for the control and the reduction of HCFC 22 leaks, the replacement of entire refrigeration systems and the preparation for the period following the availability of HCFC 22. The author offered twelve conclusions. 10 refs., 9 figs.

The importance of the ammonia purification process in ammonia-water absorption systems

International Nuclear Information System (INIS)

Fernandez-Seara, Jose; Sieres, Jaime

2006-01-01

Practical experience in working with ammonia-water absorption systems shows that the ammonia purification process is a crucial issue in order to obtain an efficient and reliable system. In this paper, the detrimental effects of the residual water content in the vapour refrigerant are described and quantified based on the system design variables that determine the effectiveness of the purification process. The study has been performed considering a single stage system with a distillation column with complete condensation. The ammonia purification effectiveness of the column is analysed in terms of the efficiencies in the stripping and rectifying sections and the reflux ratio. By varying the efficiencies from 0 to 1, systems with neither the rectifying nor stripping section, with either the rectifying or stripping section, or with both sections can be considered. The impact of the ammonia purification process on the absorption system performance is studied based on the column efficiencies and reflux ratio; and its effects on refrigerant concentration, system COP, system pressures and main system mass flow rates and concentrations are analysed. When the highest efficiency rectifying sections are used a combination of generation temperature and reflux ratio which leads to optimum COP values is found. The analysis covers different operating conditions with air and water cooled systems from refrigeration to air conditioning applications by changing the evaporation temperature. The importance of rectification in each kind of application is evaluated

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.

Trigeneration integrated with absorption enhanced reforming of lignite and biomass

Energy Technology Data Exchange (ETDEWEB)

Yaodong Wang; Ye Huang; Anthony P. Roskilly [Newcastle University, Newcastle Upon Tyne (United Kingdom). Sir Joseph Swan Institute for Energy Research

2009-10-15

A technical investigation of an innovative trigeneration integrated with absorption enhanced reforming (AER) of lignite and biomass is carried out using the ECLIPSE process simulator. The system includes an internal combustion engine, an AER gasifier, a waste heat recovery and storage unit and an absorption refrigerator. The whole system is operated in the following sequence: The AER gasifier is used to generate hydrogen using lignite and biomass; the hydrogen generated is used to run the engine which drives a generator to produce electricity. Additionally, the heat recovery unit collects waste heat from the engine and is used to supply hot water and space heating. Furthermore, the waste heat is used to operate the absorption refrigerator. The electricity, heat and cooling can be used to meet the energy requirements for the households in a village, a resident building or a commercial building, or a supermarket. Within the study, the effects of lignite mixed with three different types of biomass (straw, willow and switch grass) on the system performance are investigated and the results are compared. The results show that it is feasible to use an AER system to reform the low quality fuels lignite and biomass to generate a cleaner fuel - hydrogen to replace fossil fuels (diesel or natural gas) and to fuel an engine based trigeneration system; the system works with high efficiencies and with a potential of carbon capture from the sorbent-regeneration process that would benefit the environment. 25 refs., 2 figs., 3 tabs.

A second law analysis and entropy generation minimization of an absorption chiller

KAUST Repository

Myat, Aung; Thu, Kyaw; Kim, Youngdeuk; Chakraborty, Anutosh; Chun, Wongee; Ng, K. C.

2011-01-01

This paper presents performance analysis of absorption refrigeration system (ARS) using an entropy generation analysis. A numerical model predicts the performance of absorption cycle operating under transient conditions along with the entropy generation computation at assorted heat source temperatures, and it captures also the dynamic changes of lithium bromide solution properties such as concentration, density, vapor pressure and overall heat transfer coefficients. An optimization tool, namely the genetic algorithm (GA), is used as to locate the system minima for all defined domain of heat source and cooling water temperatures. The analysis shows that minimization of entropy generation the in absorption cycle leads to the maximization of the COP. © 2011 Elsevier Ltd. All rights reserved.

A second law analysis and entropy generation minimization of an absorption chiller

KAUST Repository

Myat, Aung

2011-10-01

This paper presents performance analysis of absorption refrigeration system (ARS) using an entropy generation analysis. A numerical model predicts the performance of absorption cycle operating under transient conditions along with the entropy generation computation at assorted heat source temperatures, and it captures also the dynamic changes of lithium bromide solution properties such as concentration, density, vapor pressure and overall heat transfer coefficients. An optimization tool, namely the genetic algorithm (GA), is used as to locate the system minima for all defined domain of heat source and cooling water temperatures. The analysis shows that minimization of entropy generation the in absorption cycle leads to the maximization of the COP. © 2011 Elsevier Ltd. All rights reserved.

Performance comparison of a refrigerator system using R134a and hydrocarbon refrigerant (HCR134a) with different expansion devices

Science.gov (United States)

Aziz, A.; Izzudin; Mainil, A. K.

2017-09-01

The objective of this study is to compare the performance of refrigerator system using working fluid between R134a refrigerant and HCR134a as hydrocarbon refrigerant for substitution of R134a. The use of capillary tube (CT) 1.5 m with HCR134a showed that slightly better COP than among the others, due to the lower pressure of condenser, conversely thermostatic expansion valve (TEV) showed that better COP than among the others with R134a. COP of CT 1.25 m and CT 1.5 m using HCR134a increase about 42.89% and 18.09% compared to R134a, where the electric current of refrigerator system decrease about 11.63% and 10.98%. However, the COP of HCR134a with CT 2.7 m and TEV were obtained lower than R134a about 16.2% and 17.06% and the use of electric current is higher than R134a about 12.98% and 16.5%. The use of HCR134a provides a higher refrigeration effect than R134a about 66.71%-88.27% for various types of expansion devices. The results confirmed that HCR134a could be an alternative refrigerant for replacement of R134a refrigerant.

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, ...

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.

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.

Improvement of a thermoelectric and vapour compression hybrid refrigerator

International Nuclear Information System (INIS)

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

2012-01-01

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

The climate change implications of manufacturing refrigerants. A calculation of 'production' energy contents of some common refrigerants

International Nuclear Information System (INIS)

Campbell, N.J.; McCulloch, A.

1998-01-01

Total Equivalent Warming Impact (TEWI) analysis has been shown to be a useful aid to quantifying the climate change effect of potential emissions from the operation of systems that involve the use of greenhouse gases and consume energy, so generating CO 2 emissions. It enables these systems to be optimized for minimum global warming impact. In previous studies, the energies required to manufacture the greenhouse gases themselves were not included; by analogy with other chemical manufacturing processes they were assumed to be small in the context of climate change. In the work described here, climate change impacts from the energy used to produce a number of common refrigerant fluids are evaluated. These impacts are compared with the potential impact on global warming from the other components of TEWI: use and disposal of the refrigerants, including direct release into the environment. It is shown that the implications for climate change of the production of traditional refrigerants like ammonia, hydrocarbons or CFC-12 and new refrigerating fluids, such as HFC-134a, are truly insignificant in comparison with other stages of the life cycle of a refrigerator and have no role in TEWI. (author)

NLP model of a LiBr–H2O absorption refrigeration system for the minimization of the annual operating cost

International Nuclear Information System (INIS)

Rubio-Maya, Carlos; Pacheco-Ibarra, J. Jesús; Belman-Flores, Juan M.; Galván-González, Sergio R.; Mendoza-Covarrubias, Crisanto

2012-01-01

In this paper the optimization of a LiBr–H 2 O absorption refrigeration system with the annual operating cost as the objective function to be minimized is presented. The optimization problem is established as a Non-Linear Programming (NLP) model allowing a formulation of the problem in a simple and structured way, and reducing the typical complexity of the thermal systems. The model is composed of three main parts: the thermodynamic model based on the exergy concept including also the proper formulation for the thermodynamic properties of the LiBr–H 2 O mixture, the second is the economic model and the third part composed by inequality constraints. The solution of the model is obtained using the CONOPT solver suitable for NLP problems (code is available on request). The results show the values of the decision variables that minimize the annual cost under the set of assumptions considered in the model and agree well with those reported in other works using different optimization approaches. - Highlights: ► The optimization of an ARS is presented using the annual operating cost as the objective function. ► The problem is established as an NLP model allowing a formulation in a simple and structured way. ► Several formulations for the thermodynamic properties were tested to implement the simpler ones. ► The results obtained agree well with those reported in the work being in comparison.

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.

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, ...

Correlation of refrigerant mass flow rate through adiabatic capillary tubes using mixture refrigerant carbondioxide and ethane for low temperature applications

Science.gov (United States)

Nasruddin, Syaka, Darwin R. B.; Alhamid, M. Idrus

2012-06-01

Various binary mixtures of carbon dioxide and hydrocarbons, especially propane or ethane, as alternative natural refrigerants to Chlorofluorocarbons (CFCs) or Hydro fluorocarbons (HFCs) are presented in this paper. Their environmental performance is friendly, with an ozone depletion potential (ODP) of zero and Global-warming potential (GWP) smaller than 20. The capillary tube performance for the alternative refrigerant HFC HCand mixed refrigerants have been widely studied. However, studies that discuss the performance of the capillary tube to a mixture of natural refrigerants, in particular a mixture of azeotrope carbon dioxide and ethane is still undeveloped. A method of empirical correlation to determine the mass flow rate and pipe length has an important role in the design of the capillary tube for industrial refrigeration. Based on the variables that effect the rate of mass flow of refrigerant in the capillary tube, the Buckingham Pi theorem formulated eight non-dimensional parameters to be developed into an empirical equations correlation. Furthermore, non-linear regression analysis used to determine the co-efficiency and exponent of this empirical correlation based on experimental verification of the results database.

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

Literature survey of heat transfer enhancement techniques in refrigeration applications

Energy Technology Data Exchange (ETDEWEB)

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

1994-05-01

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

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....

Prediction of thermodynamic properties of refrigerants using data mining

International Nuclear Information System (INIS)

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

2011-01-01

The analysis of vapor compression refrigeration systems requires the availability of simple and efficient mathematical formulations for the determination of thermodynamic properties of refrigerants. The aim of this study is to determine thermodynamic properties as enthalpy, entropy and specific volume of alternative refrigerants using data mining method. Alternative refrigerants used in the study are R134a, R404a, R407c and R410a. The results obtained from data mining have been compared to actual data from the literature. The study shows that the data mining methodology is successfully applicable to determine enthalpy, entropy and specific volume values for any temperature and pressure of refrigerants. Therefore, computation time reduces and simulation of vapor compression refrigeration systems is fairly facilitated.

Exergy analysis of refrigerators for large scale cooling systems

Energy Technology Data Exchange (ETDEWEB)

Loehlein, K [Sulzer Cryogenics, Winterthur (Switzerland); Fukano, T [Nippon Sanso Corp., Kawasaki (Japan)

1993-01-01

Facilities with superconducting magnets require cooling capacity at different temperature levels and of different types (refrigeration or liquefaction). The bigger the demand for refrigeration, the more investment for improved efficiency of the refrigeration plant is justified and desired. Refrigeration cycles are built with discrete components like expansion turbines, cold compressors, etc. Therefore the exergetic efficiency for producing refrigeration on a distinct temperature level is significantly dependent on the 'thermodynamic arrangement' of these components. Among a variety of possibilities, limited by the range of applicability of the components, one has to choose the best design for higher efficiency on every level. Some influences are being quantified and aspects are given for a optimal integration of the refrigerator into the whole cooling system. (orig.).

Near-infrared free carrier absorption in heavily doped silicon

International Nuclear Information System (INIS)

Baker-Finch, Simeon C.; McIntosh, Keith R.; Yan, Di; Fong, Kean Chern; Kho, Teng C.

2014-01-01

Free carrier absorption in heavily doped silicon can have a significant impact on devices operating in the infrared. In the near infrared, the free carrier absorption process can compete with band to band absorption processes, thereby reducing the number of available photons to optoelectronic devices such as solar cells. In this work, we fabricate 18 heavily doped regions by phosphorus and boron diffusion into planar polished silicon wafers; the simple sample structure facilitates accurate and precise measurement of the free carrier absorptance. We measure and model reflectance and transmittance dispersion to arrive at a parameterisation for the free carrier absorption coefficient that applies in the wavelength range between 1000 and 1500 nm, and the range of dopant densities between ∼10 18 and 3 × 10 20  cm −3 . Our measurements indicate that previously published parameterisations underestimate the free carrier absorptance in phosphorus diffusions. On the other hand, published parameterisations are generally consistent with our measurements and model for boron diffusions. Our new model is the first to be assigned uncertainty and is well-suited to routine device analysis

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...

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

Basics of Low-temperature Refrigeration

CERN Document Server

Alekseev, A.

2014-07-17

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

Basics of Low-temperature Refrigeration

Energy Technology Data Exchange (ETDEWEB)

Alekseev, A [Linde AG, Munich (Germany)

2014-07-01

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

Geospatial Absorption and Regional Effects

Directory of Open Access Journals (Sweden)

IOAN MAC

2009-01-01

Full Text Available The geospatial absorptions are characterized by a specific complexity both in content and in their phenomenological and spatial manifestation fields. Such processes are differentiated according to their specificity to pre-absorption, absorption or post-absorption. The mechanisms that contribute to absorption are extremely numerous: aggregation, extension, diffusion, substitution, resistivity (resilience, stratification, borrowings, etc. Between these mechanisms frequent relations are established determining an amplification of the process and of its regional effects. The installation of the geographic osmosis phenomenon in a given territory (a place for example leads to a homogenization of the geospatial state and to the installation of the regional homogeneity.

Evaluation of Virtual Refrigerant Mass Flow Sensors

OpenAIRE

Kim, Woohyun; Braun, James E.

2012-01-01

Refrigerant mass flow rate is an important measurement for monitoring equipment performance and enabling fault detection and diagnostics. However, a traditional mass flow meter is expensive to purchase and install. A virtual refrigerant mass flow sensor (VRMF) uses a mathematical model to estimate flow rate using low-cost measurements and can potentially be implemented at low cost. This study evaluates three VRMFs for estimating refrigerant mass flow rate. The first model uses a compressor ma...

Energy consumption of small refrigerators - Information leaflet; Merkblatt Kleinkuehlschrank

Energy Technology Data Exchange (ETDEWEB)

NONE

2009-07-01

In this leaflet published by the Swiss Federal Office of Energy (SFOE), the energy consumption of small refrigerators with a capacity of less than 100 litres is reported on. Such small refrigerators are often used in hotel rooms or in campers. It is noted that, in comparison, a typical, 150 litre class A++ domestic refrigerator uses only a fraction of the amount of energy used by such small refrigerators. The results of measurements made according to EN 153 and ISO 15502 norms are discussed. Recommendations are made on the purchase and operation of these small refrigerators.

Compatibility of refrigerants and lubricants with elastomers. Final report

Energy Technology Data Exchange (ETDEWEB)

Hamed, G.R.; Seiple, R.H.; Taikum, Orawan

1994-01-01

The information contained in this report is designed to assist the air-conditioning and refrigeration industry in the selection of suitable elastomeric gasket and seal materials that will prove useful in various refrigerant and refrigeration lubricant environments. In part I of the program the swell behavior in the test fluids has been determined using weight and in situ diameter measurements for the refrigerants and weight, diameter and thickness measurements for the lubricants. Weight and diameter measurements are repeated after 2 and 24 hours for samples removed fro the refrigerant test fluids and 24 hours after removal from the lubricants. Part II of the testing program includes the evaluation of tensile strength, hardness, weight, and dimensional changes after immersion aging in refrigerant/lubricant mixtures of selected elastomer formulations at elevated temperature and pressure.

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.

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

International Nuclear Information System (INIS)

Shimazaki, Yoichi

2003-01-01

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

Fault detection and diagnosis for refrigerator from compressor sensor

Science.gov (United States)

Keres, Stephen L.; Gomes, Alberto Regio; Litch, Andrew D.

2016-12-06

A refrigerator, a sealed refrigerant system, and method are provided where the refrigerator includes at least a refrigerated compartment and a sealed refrigerant system including an evaporator, a compressor, a condenser, a controller, an evaporator fan, and a condenser fan. The method includes monitoring a frequency of the compressor, and identifying a fault condition in the at least one component of the refrigerant sealed system in response to the compressor frequency. The method may further comprise calculating a compressor frequency rate based upon the rate of change of the compressor frequency, wherein a fault in the condenser fan is identified if the compressor frequency rate is positive and exceeds a condenser fan fault threshold rate, and wherein a fault in the evaporator fan is identified if the compressor frequency rate is negative and exceeds an evaporator fan fault threshold rate.

Evaluation of mass absorption in LiBr flat-fan sheets

International Nuclear Information System (INIS)

Palacios, E.; Izquierdo, M.; Marcos, J.D.; Lizarte, R.

2009-01-01

Experiments were conducted to determine the absorption rates of refrigerant vapour in an aqueous lithium bromide flat-fan sheet for use in absorption air-conditioning systems. The solution flow rates tested ranged from 0.023 to 0.054 kg/s (84-194 kg/h), with pressure losses in the injection nozzle of from 40 to 250 kPa. The effect of the mass flow rate on both solution residence time and the sheet deformation rate was also analyzed in absorption chambers of a pre-defined length, along with the effect of the sub-cooling temperature on the amount of vapour absorbed. The downstream evolution of approach to equilibrium factor F was quantified. The mass transfer coefficient values were found to be over 3 x 10 -4 m/s. In absorption chambers 100 mm long, over 0.8 g/s l of vapour were absorbed per chamber absorption volume. Moreover, about 600 g of vapour were absorbed per kJ of solution flow work. Flat-fan sheet configurations were found to perform better than falling film and spray absorbers.

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.

A feasibility analysis of replacing the standard ammonia refrigeration device with the cascade NH3/CO2 refrigeration device in the food industry

Directory of Open Access Journals (Sweden)

Jankovich Dennis

2015-01-01

Full Text Available The thermodynamic analysis demonstrates the feasibility of replacing the standard ammonia refrigeration device with the cascade NH3/CO2 refrigeration device in the food industry. The main reason for replacement is to reduce the total amount of ammonia in spaces like deep-freezing chambers, daily chambers, working rooms and technical passageways. An ammonia-contaminated area is hazardous to human health and the safety of food products. Therefore the preferred reduced amount of ammonia is accumulated in the Central Refrigeration Engine Room, where the cascade NH3/CO2 device is installed as well. Furthermore, the analysis discusses and compares two left Carnot¢s refrigeration cycles, one for the standard ammonia device and the other for the cascade NH3/CO2 device. Both cycles are processes with two-stage compression and two-stage throttling. The thermodynamic analysis demonstrates that the selected refrigeration cycle is the most cost-effective process because it provides the best numerical values for the total refrigeration factor with respect to the observed refrigeration cycle. The chief analyzed influential parameters of the cascade device are: total refrigeration load, total reactive power, mean temperature of the heat exchanger, evaporating and condensing temperature of the low-temperature part.

Ecological optimization for generalized irreversible Carnot refrigerators

International Nuclear Information System (INIS)

Chen Lingen; Zhu Xiaoqin; Sun Fengrui; Wu Chih

2005-01-01

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

Modeling of thermodynamic properties of refrigerant/absorbent couples using data mining process

International Nuclear Information System (INIS)

Sencan, Arzu

2007-01-01

In this paper, in order to determine thermodynamic properties of two alternative refrigerant/absorbent couples (methanol/LiBr and methanol/LiCl), a data mining process was used. These fluid couples can be used in absorption heat pump systems, and their main advantage is that they do not cause ozone depletion. In order to train the network, limited experimental measurements were used as training and test data. In the present study, linear regression (LR), pace regression (PR), sequential minimal optimization (SMO), M5 model tree, M5'Rules and back propagation neural network (BPNN) models are applied within the data mining process for determining the specific volume of the methanol/LiBr and methanol/LiCl fluid couples. The best result was obtained by using the back propagation model. A new formulation is presented for determination of the specific volumes of the two refrigerant/absorbent couples. The use of this new formulation, which can be employed with any programming language or spreadsheet program for estimation of the specific volumes of fluid couples, as described in this paper, may make the use of dedicated BPNN software unnecessary

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.

Shuttle Kit Freezer Refrigeration Unit Conceptual Design

Science.gov (United States)

Copeland, R. J.

1975-01-01

The refrigerated food/medical sample storage compartment as a kit to the space shuttle orbiter is examined. To maintain the -10 F in the freezer kit, an active refrigeration unit is required, and an air cooled Stirling Cycle refrigerator was selected. The freezer kit contains two subsystems, the refrigeration unit, and the storage volume. The freezer must provide two basic capabilities in one unit. One requirement is to store 215 lbs of food which is consumed in a 30-day period by 7 people. The other requirement is to store 128.3 lbs of medical samples consisting of both urine and feces. The unit can be mounted on the lower deck of the shuttle cabin, and will occupy four standard payload module compartments on the forward bulkhead. The freezer contains four storage compartments.

Public Refrigerated Warehouses

Data.gov (United States)

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

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

Energy Technology Data Exchange (ETDEWEB)

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

1995-07-15

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

Time-Temperature Profiling of United Kingdom Consumers' Domestic Refrigerators.

Science.gov (United States)

Evans, Ellen W; Redmond, Elizabeth C

2016-12-01

Increased consumer demand for convenience and ready-to-eat food, along with changes to consumer food purchase and storage practices, have resulted in an increased reliance on refrigeration to maximize food safety. Previous research suggests that many domestic refrigerators operate at temperatures exceeding recommendations; however, the results of several studies were determined by means of one temperature data point, which, given temperature fluctuation, may not be a true indicator of actual continual operating temperatures. Data detailing actual operating temperatures and the effects of consumer practices on temperatures are limited. This study has collated the time-temperature profiles of domestic refrigerators in consumer kitchens (n = 43) over 6.5 days with concurrent self-reported refrigerator usage. Overall, the findings established a significant difference (P < 0.05) between one-off temperature (the recording of one temperature data point) and mean operating temperature. No refrigerator operated at ≤5.0°C for the entire duration of the study. Mean temperatures exceeding 5.0°C were recorded in the majority (91%) of refrigerators. No significant associations or differences were determined for temperature profiles and demographics, including household size, or refrigerator characteristics (age, type, loading, and location). A positive correlation (P < 0.05) between room temperature and refrigerator temperature was determined. Reported door opening frequency correlated with temperature fluctuation (P < 0.05). Thermometer usage was determined to be infrequent. Cumulatively, research findings have established that the majority of domestic refrigerators in consumer homes operate at potentially unsafe temperatures and that this is influenced by consumer usage. The findings from this study may be utilized to inform the development of shelf-life testing based on realistic domestic storage conditions. Furthermore, the data can inform the development of future

Efficiency analysis of alternative refrigerants for ejector cooling cycles

International Nuclear Information System (INIS)

Gil, Bartosz; Kasperski, Jacek

2015-01-01

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

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.

Classification of refrigerants; Classification des fluides frigorigenes

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-07-01

This document was made from the US standard ANSI/ASHRAE 34 published in 2001 and entitled 'designation and safety classification of refrigerants'. This classification allows to clearly organize in an international way the overall refrigerants used in the world thanks to a codification of the refrigerants in correspondence with their chemical composition. This note explains this codification: prefix, suffixes (hydrocarbons and derived fluids, azeotropic and non-azeotropic mixtures, various organic compounds, non-organic compounds), safety classification (toxicity, flammability, case of mixtures). (J.S.)

Optimizing the Thermoacoustic Pulse Tube Refrigerator Performances

Directory of Open Access Journals (Sweden)

E. V. Blagin

2014-01-01

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

Computer modeling of commercial refrigerated warehouse facilities

International Nuclear Information System (INIS)

Nicoulin, C.V.; Jacobs, P.C.; Tory, S.

1997-01-01

The use of computer models to simulate the energy performance of large commercial refrigeration systems typically found in food processing facilities is an area of engineering practice that has seen little development to date. Current techniques employed in predicting energy consumption by such systems have focused on temperature bin methods of analysis. Existing simulation tools such as DOE2 are designed to model commercial buildings and grocery store refrigeration systems. The HVAC and Refrigeration system performance models in these simulations tools model equipment common to commercial buildings and groceries, and respond to energy-efficiency measures likely to be applied to these building types. The applicability of traditional building energy simulation tools to model refrigerated warehouse performance and analyze energy-saving options is limited. The paper will present the results of modeling work undertaken to evaluate energy savings resulting from incentives offered by a California utility to its Refrigerated Warehouse Program participants. The TRNSYS general-purpose transient simulation model was used to predict facility performance and estimate program savings. Custom TRNSYS components were developed to address modeling issues specific to refrigerated warehouse systems, including warehouse loading door infiltration calculations, an evaporator model, single-state and multi-stage compressor models, evaporative condenser models, and defrost energy requirements. The main focus of the paper will be on the modeling approach. The results from the computer simulations, along with overall program impact evaluation results, will also be presented

New possibilities for non-CFC refrigeration

International Nuclear Information System (INIS)

Lorentzen, G.; Pettersen, J.

1992-01-01

There is a widespread belief that the only viable refrigerants in most applications are new fluorocarbon chemicals. This trend will eventually result in emissions of several hundred thousand tons of new chemicals to the atmosphere each year, involving potential risk of unforeseen environmental effects. A number of other options exist, or may be developed. By using substances which already have a natural role in our ecosystems, some uncertainty related to the critical issue of our future environment can be avoided. By development and practical testing of a laboratory prototype it has been documented that carbon dioxide is a viable refrigerant in automobile air conditioners, completely solving all environmental problems associated with such systems. General use of CO 2 as a refrigerant may provide a number of advantages in the present situation, both from an environmental and practical point of view. It is our considered opinion that the old carbon dioxide offers a key to the complete solution of the environmental problems in many areas of refrigeration usage. 19 refs., 8 figs., 5 tabs

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...

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.

Wine absorption by cork stoppers research in foods

Energy Technology Data Exchange (ETDEWEB)

Gonzalez-Adrados, J. R.; Gonzalez-Hernandez, F.; Garcia de Ceca, J. L.; Caceres-Esteban, M. J.; Garcia-Vallejo, M. C.

2008-07-01

To evaluate the magnitude of wine absorption by cork under conditions as close to reality as possible and its evolution in time, ready-to-use natural cork stoppers and ''1+1'' cork stoppers were used to close bottles filled with red wine. Stoppers were removed after 3, 6, 12 and 24 months of contact to determine absorption of liquid and liquid progression along the lateral surface of the cork stopper.Variation of absorption with contact time was studied by adjusting the model Absorption = a {radical} t(R{sup 2}: 82.19 - 93.63%). A scheme of the evolution of wine absorption with time is proposed, differentiating liquid flow along cork-glass interface, diffusion in cell walls and liquid flow through the cell lumens. In conditions of use, a value of 4.48.10{sup 1}3 m{sup 2} s{sup -}1 was obtained for non-radial diffusion coefficient (D). (Author) 13 refs.

Diffuse interstellar clouds

International Nuclear Information System (INIS)

Black, J.H.

1987-01-01

The author defines and discusses the nature of diffuse interstellar clouds. He discusses how they contribute to the general extinction of starlight. The atomic and molecular species that have been identified in the ultraviolet, visible, and near infrared regions of the spectrum of a diffuse cloud are presented. The author illustrates some of the practical considerations that affect absorption line observations of interstellar atoms and molecules. Various aspects of the theoretical description of diffuse clouds required for a full interpretation of the observations are discussed

Condensation of nano-refrigerant inside a horizontal tube

Science.gov (United States)

Darzi, Milad; Sadoughi, M. K.; Sheikholeslami, M.

2018-05-01

In this paper, condensing pressure drop of refrigerant-based nanofluid inside a tube is studied. Isobutene was selected as the base fluid while CuO nanoparticles were utilized to prepare nano-refrigerant. However, for the feasibility of nanoparticle dispersion into the refrigerant, Polyester oil (POE) was utilized as lubricant oil and added to the pure refrigerant by 1% mass fraction. Various values of mass flux, vapor quality, concentration of nanoparticle are investigated. Results indicate that adding nanoparticles leads to enhance frictional pressure drop. Nanoparticles caused larger pressure drop penalty at relatively lower vapor qualities which may be attributed to the existing condensation flow pattern such that annular flow is less influenced by nanoparticles compared to intermittent flow regime.

Performance of a Throttle Cycle Refrigerator with Nitrogen-Hydrocarbon and Argon-Hydrocarbon Mixtures

Science.gov (United States)

Venkatarathnam, G.; Senthil Kumar, P.; Srinivasa Murthy, S.

2004-06-01

Throttle cycle refrigerators are a class of vapor compression refrigerators that can provide refrigeration at cryogenic temperatures and operate with refrigerant mixtures. The performance of our prototype refrigerators with nitrogen-hydrocarbon, nitrogen-hydrocarbon-helium and argon-hydrocarbon refrigerant mixtures is presented in this paper.

Absorption refrigeration cycle applied to offshore platforms; Refrigeracao por absorcao aplicada a plataformas de petroleo

Energy Technology Data Exchange (ETDEWEB)

Ferreira, Maximino Joaquim Pina [KROMAV Engenharia, Rio de Janeiro, RJ (Brazil); Pinto, Luiz Antonio Vaz; Belchior, Carlos Rodrigues Pereira [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE)

2004-07-01

To produce cold from the heat seems a task unlikely or even impossible. However, absorption systems produce cooling from heat sources and it exist since the century XIX. In industrial places is very important to improve the energy use, even more in places where the activities involve great costs and incomes. Traditionally the alternatives conflict in the aspects of initial and operational costs. This paper describes the absorption systems operation and its main advantages and disadvantages, when compared to the traditional systems with compressor. The known fact that a vapor compressor system presents larger efficiency is not enough to validate it for all of the applications. In this sense, the initial and operational analysis of the costs of the absorption systems becomes interesting. In spite of, double effect absorption systems are demonstrating the evolution of the absorption cycle in order to obtain better performance. Turbo-generators and Turbo-compressors of the offshore platforms are thermal machines that reject great amount of heat in the exhaust gases. This heat is used for heating of water used in the Process Plant. The processes of separation of the mixture water-oil-gas from the well, for instance, use that heat. Even after the passage of the water in the Plant of Process, the residual heat is still enough for the use in absorption systems. A simulation is done using real data of an offshore platform. Two possible alternatives are compared under technical and economical aspects. Sensibility analysis is also performed in order to verify possible impacts of variations of electric power cost. (author)

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.

REFRIGERANT/LUBRICANT MIXTURES: PROBLEMS OF APPLICATION AND PROPERTY RESEARCH

Directory of Open Access Journals (Sweden)

Yu. Semenyuk

2013-10-01

Full Text Available The results and generalizations of thermophysical property research for the refrigerant/lubricant mixtures are summarized. The methodological aspects of the experimental studies of the thermal properties of real working media for vapor compression refrigeration machines and the general principles of the thermodynamic properties simulation for such solutions are analyzed. It is shown that the admixtures of compressor oil in the refrigerant make the efficiency parameters of compressor systems much lower. The question of a selective solubility of the multicomponent refrigerants in compressor oils is discussed.

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.

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

International Nuclear Information System (INIS)

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

2015-01-01

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

Absorption and Metabolism of Xanthophylls

OpenAIRE

Kotake-Nara, Eiichi; Nagao, Akihiko

2011-01-01

Dietary carotenoids, especially xanthophylls, have attracted significant attention because of their characteristic biological activities, including anti-allergic, anti-cancer, and anti-obese actions. Although no less than forty carotenoids are ingested under usual dietary habits, only six carotenoids and their metabolites have been found in human tissues, suggesting selectivity in the intestinal absorption of carotenoids. Recently, facilitated diffusion in addition to simple diffusion has bee...

The fortran programme for the calculation of the absorption and double scattering corrections in cross-section measurements with fast neutrons using the monte Carlo method (1963); Programme fortran pour le calcul des corrections d'absorption et de double diffusion dans les mesures de sections efficaces pour les neutrons rapides par la methode de monte-carlo (1963)

Energy Technology Data Exchange (ETDEWEB)

Fernandez, B [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1963-07-01

A calculation for double scattering and absorption corrections in fast neutron scattering experiments using Monte-Carlo method is given. Application to cylindrical target is presented in FORTRAN symbolic language. (author) [French] Un calcul des corrections de double diffusion et d'absorption dans les experiences de diffusion de neutrons rapides par la methode de Monte-Carlo est presente. L'application au cas d'une cible cylindrique est traitee en langage symbolique FORTRAN. (auteur)

Refrigeration plants for the SSCL

International Nuclear Information System (INIS)

McAshan, M.; Ganni, V.; Than, R.; Niehaus, T.

1991-03-01

The basic requirements and operating features of the collider cryogenic system have already been described in other publications. The general arrangement of the refrigeration plant and its subsystems is presented, and the issue of how to provide redundancy in the cryogenic system is addressed, and some of the basic features of the refrigeration plants are described. The collider cryogenic system design is not final yet, and this report only reflects the direction and current status of the cryogenic system design

Refrigeration processes a practical handbook on the physical properties of refrigerants and their applications

CERN Document Server

Meacock, H M

1979-01-01

A comprehensive applications-oriented treatment of the subject in two parts. The first part forms a useful introduction to basic principles dealing with the definitions of the physical properties and outlines the method of their calculation. The second part is devoted to calculated data on a range of refrigerants by means of extensive tables and diagrams. The treatment takes the form of a data sheet, one for each of about thirty refrigerants; this data sheet gives the essential information from which close approximations of pressure, temperature, volume and enthalpy can be made for any predict

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.

Oxide ion diffusion mechanism related to Co and Fe ions in (Ba0.5Sr0.5)(Co0.8Fe0.2)O3-δ using in-situ X-ray absorption spectroscopy

Science.gov (United States)

Itoh, Takanori; Imai, Hideto

2018-03-01

The time changes of the white line and pre-edge intensities of Co and Fe K-edge in (Ba0.5Sr0.5)(Co0.8Fe0.2)O3-δ (BSCF) were observed to estimate the oxide ion diffusion related to Co and Fe ions by using in - situ X-ray absorption spectroscopy (XAS) during oxidation. The 20 μm self-standing BSCF film was prepared for in - situ XAS measurements. The time changes of absorption were fitted to the exponential decay function with two terms. The longer relaxation time (τ), related to the oxide ion diffusion during the oxidation of BSCF, is dependent on temperature. The oxide ion diffusion coefficients (D) were calculated from the τ s estimated by in - situ XAS. The values of the activation energy (Ea) for D related to Co K-edge white line, Co pre-edge, and Fe pre-edge were 1.8-2.0 eV. The value of Ea for D related to Fe K-edge white line, however, was higher than other absorption values at approximately 2.3 eV. We discussed the oxide ion diffusion mechanism related to Co and Fe ions in BSCF using in - situ XAS.

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

Directory of Open Access Journals (Sweden)

V. G. Bukin

2012-01-01

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

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.

Magnetic refrigeration--towards room-temperature applications

International Nuclear Information System (INIS)

Brueck, E.; Tegus, O.; Li, X.W.; Boer, F.R. de; Buschow, K.H.J.

2003-01-01

Modern society relies very much on readily available cooling. Magnetic refrigeration based on the magneto-caloric effect (MCE) has become a promising competitive technology for the conventional gas-compression/expansion technique in use today. Recently, there have been two breakthroughs in magnetic-refrigeration research: one is that American scientists demonstrated the world's first room-temperature, permanent-magnet, magnetic refrigerator; the other one is that we discovered a new class of magnetic refrigerant materials for room-temperature applications. The new materials are manganese-iron-phosphorus-arsenic (MnFe(P,As)) compounds. This new material has important advantages over existing magnetic coolants: it exhibits a huge MCE, which is larger than that of Gd metal; and its operating temperature can be tuned from about 150 to about 335 K by adjusting the P/As ratio. Here we report on further improvement of the materials by increasing the Mn content. The large entropy change is attributed to a field-induced first-order phase transition enhancing the effect of the applied magnetic field. Addition of Mn reduces the thermal hysteresis, which is intrinsic to the first-order transition. This implies that already moderate applied magnetic fields of below 2 T may suffice

Contribution to magnetic refrigeration study at liquid helium study

International Nuclear Information System (INIS)

Lacaze, A.

1985-10-01

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

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.

Food Safety Practices Linked with Proper Refrigerator Temperatures in Retail Delis.

Science.gov (United States)

Brown, Laura G; Hoover, Edward Rickamer; Faw, Brenda V; Hedeen, Nicole K; Nicholas, David; Wong, Melissa R; Shepherd, Craig; Gallagher, Daniel L; Kause, Janell R

2018-05-01

Listeria monocytogenes (L. monocytogenes) causes the third highest number of foodborne illness deaths annually. L. monocytogenes contamination of sliced deli meats at the retail level is a significant contributing factor to L. monocytogenes illness. The Centers for Disease Control and Prevention's Environmental Health Specialists Network (EHS-Net) conducted a study to learn more about retail delis' practices concerning L. monocytogenes growth and cross-contamination prevention. This article presents data from this study on the frequency with which retail deli refrigerator temperatures exceed 41°F, the Food and Drug Administration (FDA)-recommended maximum temperature for ready-to-eat food requiring time and temperature control for safety (TCS) (such as retail deli meat). This provision was designed to control bacterial growth in TCS foods. This article also presents data on deli and staff characteristics related to the frequency with which retail delis refrigerator temperatures exceed 41°F. Data from observations of 445 refrigerators in 245 delis showed that in 17.1% of delis, at least one refrigerator was >41°F. We also found that refrigeration temperatures reported in this study were lower than those reported in a related 2007 study. Delis with more than one refrigerator, that lacked refrigerator temperature recording, and had a manager who had never been food safety certified had greater odds of having a refrigerator temperature >41°F. The data from this study suggest that retail temperature control is improving over time. They also identify a food safety gap: some delis have refrigerator temperatures that exceed 41°F. We also found that two food safety interventions were related to better refrigerated storage practices: kitchen manager certification and recording refrigerated storage temperatures. Regulatory food safety programs and the retail industry may wish to consider encouraging or requiring kitchen manager certification and recording refrigerated

Solid tissue simulating phantoms having absorption at 970 nm for diffuse optics

Science.gov (United States)

Kennedy, Gordon T.; Lentsch, Griffin R.; Trieu, Brandon; Ponticorvo, Adrien; Saager, Rolf B.; Durkin, Anthony J.

2017-07-01

Tissue simulating phantoms can provide a valuable platform for quantitative evaluation of the performance of diffuse optical devices. While solid phantoms have been developed for applications related to characterizing exogenous fluorescence and intrinsic chromophores such as hemoglobin and melanin, we report the development of a poly(dimethylsiloxane) (PDMS) tissue phantom that mimics the spectral characteristics of tissue water. We have developed these phantoms to mimic different water fractions in tissue, with the purpose of testing new devices within the context of clinical applications such as burn wound triage. Compared to liquid phantoms, cured PDMS phantoms are easier to transport and use and have a longer usable life than gelatin-based phantoms. As silicone is hydrophobic, 9606 dye was used to mimic the optical absorption feature of water in the vicinity of 970 nm. Scattering properties are determined by adding titanium dioxide, which yields a wavelength-dependent scattering coefficient similar to that observed in tissue in the near-infrared. Phantom properties were characterized and validated using the techniques of inverse adding-doubling and spatial frequency domain imaging. Results presented here demonstrate that we can fabricate solid phantoms that can be used to simulate different water fractions.

Applications of magnetic refrigeration and its assessment. A feasibility study - Final report

Energy Technology Data Exchange (ETDEWEB)

Kitanovski, A.; Diebold, M.; Vuarnoz, D.; Gonin, C.; Egolf, P. W.

2008-04-15

Magnetic refrigeration has the potential to replace conventional refrigeration systems - with often problematic refrigerants - in several niche markets or even some main markets of the refrigeration domain. Based on this insight the Swiss Federal Office of Energy has asked a division of the University of Applied Sciences of Western Switzerland (HEIG-VD) in Yverdon-les-Bains to list all possible refrigeration technologies and to evaluate the potential of magnetic refrigeration for these specific applications. The HEIG-VD researchers have developed a calculation tool to determine the coefficient of performance (COP) value and the exergy efficiency as a function of the magnetic field strength and the rotation frequency of a rotary type of magnetic refrigerator. The considered machine design is based on a patent, which was deposited by these scientists. Based on this work, it is found that especially two applications are very interesting for a closer investigation: the household refrigerator without a freezing compartment and the central chilling unit, which may be of large size. In the domains of refrigeration, where magnetic refrigeration could be successfully applied, the costs for magnetic refrigeration machines would be a little higher than those of the conventional ones. On the other hand the study shows possibilities how the magnetic refrigeration machines could reach higher COP values than those of the corresponding gas compression/expansion machines. Therefore, for magnetic refrigeration one may assume lower costs of operation. For large systems - as e.g. chiller units - it should be studied, if superconducting magnets could be economically applied. (author)

Evaluation of the introduction of cogeneration for refrigeration in the fisheries sector of the Amazon; Avaliacao da introducao da cogeracao para refrigeracao no setor pesqueiro do Amazonas

Energy Technology Data Exchange (ETDEWEB)

Cruz, Ricardo Wilson Aguiar da [Universidade Estadual do Amazonas (UEA), Manaus (Brazil)], e-mail: rcruz@uea.edu.br; Nebra, Silvia Azucena [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Faculdade de Engenharia Mecanica], e-mail: sanebra@fem.unicamp.br; Cartaxo, Elizabeth Ferreira [Universidade Federal do Amazonas (UFAM), Manaus, AM (Brazil)], e-mail: ecartaxo@ufam.edu.br

2004-07-01

This work analyses the opportunity to introduce cogeneration for the production of aquammonia absorption refrigeration in the autonomous Amazons State power system, by one hand as a means to improve its efficiency and by another, solve the deficiency the State has to store its fish-ing production. (author)

Designing a magnet for magnetic refrigeration

Energy Technology Data Exchange (ETDEWEB)

Bjoerk, R

2010-03-15

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

Hydrophilic structures for condensation management in refrigerator appliances

Science.gov (United States)

Kuehl, Steven John; Vonderhaar, John J; Wu, Guolian; Wu, Mianxue

2014-10-21

A refrigerator appliance that includes a freezer compartment having a freezer compartment door, and a refrigeration compartment having at least one refrigeration compartment door. The appliance further includes a mullion with an exterior surface. The mullion divides the compartments and the exterior surface directs condensation toward a transfer point. The appliance may also include a cabinet that houses the compartments and has two sides, each with an exterior surface. Further, at least one exterior surface directs condensation toward a transfer point.

Data mining techniques for thermophysical properties of refrigerants

International Nuclear Information System (INIS)

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

2009-01-01

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

OPTIONS FOR REDUCING REFRIGERANT EMISSIONS FROM SUPERMARKET SYSTEMS

Science.gov (United States)

The report was prepared to assist personnel responsible for the design, construction, and maintenance of retail food refrigeration equipment in making knowledgeable decisions regarding the implementation of refrigerant-emissions-reducing practices and technologies. It characteriz...

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.

Water, a Refrigerant (L`eau, un Frigorigène)

DEFF Research Database (Denmark)

Paul, Joachim

2003-01-01

In the light of the ongoing discussions about the availability and the future of synthetic or natural refrigerants "water" is the most attractive fluid for chillers and icemakers because of the low energy demand, the intrinsic safety and the low costs both for the fluid itself and for the install......In the light of the ongoing discussions about the availability and the future of synthetic or natural refrigerants "water" is the most attractive fluid for chillers and icemakers because of the low energy demand, the intrinsic safety and the low costs both for the fluid itself...... since many years any refrigerant with OPD and GWP, Denmark has put up a law in 2001 which includes hefty taxes on HFC. This tax is added to the price of refrigerants and lies between 17 and 44 EURO/kg for the common fluids. The goal of taxation is clear: To make GWP refrigerants unattractive because...... of their price. In conjunction with tax comes a phase-out scenario which shall be effective from 2006. The options for "natural" refrigerants without ODP and GWP are limited to five fluids which are ammonia (toxic), carbon dioxide (very high pressures), hydrocarbons (flammable), air (relatively low efficiencies...

Refrigeration Cycle Design for Refrigerant Mixtures by Molecular Simulation

Czech Academy of Sciences Publication Activity Database

Smith, W.R.; Francová, Magda; Kowalski, M.; Nezbeda, Ivo

2010-01-01

Roč. 75, č. 4 (2010), s. 383-391 ISSN 0010-0765 R&D Projects: GA AV ČR IAA400720710 Grant - others:NSERC(CA) OGP1041 Institutional research plan: CEZ:AV0Z40720504 Keywords : refrigerants * molecular simulation s * vapor–liquid equilibrium Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.853, year: 2010

Load forecasting for supermarket refrigeration

DEFF Research Database (Denmark)

Bacher, Peder; Madsen, Henrik; Aalborg Nielsen, Henrik

This report presents a study of models for forecasting the load for supermarket refrigeration. The data used for building the forecasting models consists of load measurements, local climate measurements and weather forecasts. The load measurements are from a supermarket located in a village...... in Denmark. The load for refrigeration is the sum of all cabinets in the supermarket, both low and medium temperature cabinets, and spans a period of one year. As input to the forecasting models the ambient temperature observed near the supermarket together with weather forecasts are used. Every hour...

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%.

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

International Nuclear Information System (INIS)

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

1994-01-01

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

Automated modelling of complex refrigeration cycles through topological structure analysis

International Nuclear Information System (INIS)

Belman-Flores, J.M.; Riesco-Avila, J.M.; Gallegos-Munoz, A.; Navarro-Esbri, J.; Aceves, S.M.

2009-01-01

We have developed a computational method for analysis of refrigeration cycles. The method is well suited for automated analysis of complex refrigeration systems. The refrigerator is specified through a description of flows representing thermodynamic sates at system locations; components that modify the thermodynamic state of a flow; and controls that specify flow characteristics at selected points in the diagram. A system of equations is then established for the refrigerator, based on mass, energy and momentum balances for each of the system components. Controls specify the values of certain system variables, thereby reducing the number of unknowns. It is found that the system of equations for the refrigerator may contain a number of redundant or duplicate equations, and therefore further equations are necessary for a full characterization. The number of additional equations is related to the number of loops in the cycle, and this is calculated by a matrix-based topological method. The methodology is demonstrated through an analysis of a two-stage refrigeration cycle.

Carnot type magnetic refrigeration below 4.2 K - computer simulation

International Nuclear Information System (INIS)

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

1984-01-01

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

Refrigerator retirement and replacement programs : lessons learned and application to an Ontario wide program

Energy Technology Data Exchange (ETDEWEB)

NONE

2006-05-15

The best practices in refrigerator retirement programs in North America were identified in an effort to develop a concept for an Ontario-wide provincial refrigerator retirement program. The report focused on describing refrigerator retirement programs, namely those programs that focused on getting rid of old secondary refrigerators. The report excluded refrigerator replacement programs, which encourage householders to retire their refrigerators early and replace them with an energy star refrigerator. However, it was noted that in several regions, both replacement and retirement programs are offered at the same time. The report provided background information on energy use by refrigerators as well as refrigerator retirement and replacement programs. Types of refrigerator retirement and replacement programs and the environmental benefits of these programs were also described. The report also addressed the potential energy impact of an Ontario-wide refrigerator retirement program as well as consumer incentive and bounties initiatives to encourage households to retire units. Other topics covered in the report included the design of typical refrigerator retirement and replacement programs; collection and recycling of retired refrigerators; reported costs of refrigerator retirement and replacement programs; as well as marketing and advertising. The role of retailers and manufacturers and reported lessons learned from refrigerator retirement and replacement were also presented. 14 refs., 6 tabs., 6 appendices.

The estimation of energy efficiency for hybrid refrigeration system

International Nuclear Information System (INIS)

Gazda, Wiesław; Kozioł, Joachim

2013-01-01

Highlights: ► We present the experimental setup and the model of the hybrid cooling system. ► We examine impact of the operating parameters of the hybrid cooling system on the energy efficiency indicators. ► A comparison of the final and the primary energy use for a combination of the cooling systems is carried out. ► We explain the relationship between the COP and PER values for the analysed cooling systems. -- Abstract: The concept of the air blast-cryogenic freezing method (ABCF) is based on an innovative hybrid refrigeration system with one common cooling space. The hybrid cooling system consists of a vapor compression refrigeration system and a cryogenic refrigeration system. The prototype experimental setup for this method on the laboratory scale is discussed. The application of the results of experimental investigations and the theoretical–empirical model makes it possible to calculate the cooling capacity as well as the final and primary energy use in the hybrid system. The energetic analysis has been carried out for the operating modes of the refrigerating systems for the required temperatures inside the cooling chamber of −5 °C, −10 °C and −15 °C. For the estimation of the energy efficiency the coefficient of performance COP and the primary energy ratio PER for the hybrid refrigeration system are proposed. A comparison of these coefficients for the vapor compression refrigeration and the cryogenic refrigeration system has also been presented.

Indirect refrigeration systems with natural refrigerants

DEFF Research Database (Denmark)

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

1998-01-01

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

Determination of the Thermophysical Properties of Nsukkanut: A ...

African Journals Online (AJOL)

The thermophysical properties of 'Nsukkanut', - a CaCl2/CaSO4 absorbent mixture used in solid absorption solar refrigeration [1], were studied in this report. The transient experimental technique of Beck and Al-Araji [12] was used in determining the effective thermal conductivity, specific heat and bulk thermal diffusivity of ...

49 CFR 176.93 - Vehicles having refrigerating or heating equipment.

Science.gov (United States)

2010-10-01

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

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.)

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

Energy Technology Data Exchange (ETDEWEB)

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

2015-03-01

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

A parasitic magnetic refrigerator for cooling superconducting magnet

International Nuclear Information System (INIS)

Nakagome, H.; Takahashi, M.; Ogiwara, H.

1988-01-01

The application of magnetic refrigeration principle at a liquid helium temperature (4.2K) is very useful for cooling a superconducting magnet for its potential of high efficiency. The magnetic refrigerator equipped with 14 pieces of GGG (gadolinium-gallium-garnet) single crystal unit (30mm in diameter 10mm in length) in the rotating disk operates along the gradient of the magnetic field produced by a racetrack superconducting magnet, whose maximum magnetic field is 4.5 Tesla and the minimum field is 1.1 Tesla. The final goal of their program is to liquefy gaseous helium evaporated from a liquid helium vessel of the racetrack superconducting magnet by the rotating magnetic refrigerator which operates by using the magnetic field of the superconducting magnet. A 0.12W refrigeration power in the 0.72rpm operation has been achieved under condition of 4.2K to 11.5K operation. The helium evaporation rate of this magnet system is estimated as the order of 10mW, and the achieved refrigeration power of 0.12W at 4.2K is sufficient for cooling the superconducting magnet

Designing a magnet for magnetic refrigeration

DEFF Research Database (Denmark)

Bjørk, Rasmus

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

Modelling refrigerant distribution in microchannel evaporators

DEFF Research Database (Denmark)

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

2009-01-01

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

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.

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.

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...

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

Toxicity Data to Determine Refrigerant Concentration Limits

Energy Technology Data Exchange (ETDEWEB)

Calm, James M.

2000-09-30

This report reviews toxicity data, identifies sources for them, and presents resulting exposure limits for refrigerants for consideration by qualified parties in developing safety guides, standards, codes, and regulations. It outlines a method to calculate an acute toxicity exposure limit (ATEL) and from it a recommended refrigerant concentration limit (RCL) for emergency exposures. The report focuses on acute toxicity with particular attention to lethality, cardiac sensitization, anesthetic and central nervous system effects, and other escape-impairing effects. It addresses R-11, R-12, R-22, R-23, R-113, R-114, R-116, R-123, R-124, R-125, R-134, R-134a, R-E134, R-141b, R-142b, R-143a, R-152a, R-218, R-227ea, R-236fa, R-245ca, R-245fa, R-290, R-500, R-502, R-600a, R-717, and R-744. It summarizes additional data for R-14, R-115, R-170 (ethane), R-C318, R-600 (n-butane), and R-1270 (propylene) to enable calculation of limits for blends incorporating them. The report summarizes the data a nd related safety information, including classifications and flammability data. It also presents a series of tables with proposed ATEL and RCL concentrations-in dimensionless form and the latter also in both metric (SI) and inch-pound (IP) units of measure-for both the cited refrigerants and 66 zerotropic and azeotropic blends. They include common refrigerants, such as R-404A, R-407C, R-410A, and R-507A, as well as others in commercial or developmental status. Appendices provide profiles for the cited single-compound refrigerants and for R-500 and R-502 as well as narrative toxicity summaries for common refrigerants. The report includes an extensive set of references.

Displacer Diameter Effect in Displacer Pulse Tube Refrigerator

Science.gov (United States)

Zhu, Shaowei

2017-12-01

Gas driving displacer pulse tube refrigerators are one of the work recovery type of pulse tube refrigerators whose theoretical efficiency is the same as Stirling refrigerators'. Its cooling power is from the displacement of the displacer. Displace diameter, rod diameter and pressure drop of the regenerator influence the displacement, which are investigated by numerical simulation. It is shown that the displacement ratio of the displacer over the piston is almost not affected by the displacer diameter at the same rod diameter ratio, or displacer with different diameters almost has the same performance.

Laser absorption spectroscopy of water vapor confined in nanoporous alumina: wall collision line broadening and gas diffusion dynamics.

Science.gov (United States)

Svensson, Tomas; Lewander, Märta; Svanberg, Sune

2010-08-02

We demonstrate high-resolution tunable diode laser absorption spectroscopy (TDLAS) of water vapor confined in nanoporous alumina. Strong multiple light scattering results in long photon pathlengths (1 m through a 6 mm sample). We report on strong line broadening due to frequent wall collisions (gas-surface interactions). For the water vapor line at 935.685 nm, the HWHM of confined molecules are about 4.3 GHz as compared to 2.9 GHz for free molecules (atmospheric pressure). Gas diffusion is also investigated, and in contrast to molecular oxygen (that moves rapidly in and out of the alumina), the exchange of water vapor is found very slow.

Being everything to anyone: Applicability of thermoacoustic technology in the commercial refrigeration market

Science.gov (United States)

Poese, Matthew E.; Smith, Robert W. M.; Garrett, Steven L.

2005-09-01

This talk will compare electrodynamically driven thermoacoustic refrigeration technology to some common implementations of low-lift vapor-compression technology. A rudimentary explanation of vapor-compression refrigeration will be presented along with some of the implementation problems faced by refrigeration engineers using compressor-based systems. These problems include oil management, compressor slugging, refrigerant leaks and the environmental impact of refrigerants. Recently, the method of evaluating this environmental impact has been codified to include the direct effects of the refrigerants on global warming as well as the so-called ``indirect'' warming impact of the carbon dioxide released during the generation (at the power plant) of the electrical power consumed by the refrigeration equipment. It is issues like these that generate commercial interest in an alternative refrigeration technology. However, the requirements of a candidate technology for adoption in a mature and risk-averse commercial refrigeration industry are as hard to divine as they are to meet. Also mentioned will be the state of other alternative refrigeration technologies like free-piston Stirling, thermoelectric and magnetocaloric as well as progress using vapor compression technology with alternative refrigerants like hydrocarbons and carbon dioxide.

Refrigeration Performance and Entropy Generation Analysis for Reciprocating Magnetic Refrigerator with Gd Plates

Directory of Open Access Journals (Sweden)

Yonghua You

2018-06-01

Full Text Available In the current work, a novel 2D numerical model of stationary grids was developed for reciprocating magnetic refrigerators, with Gd plates, in which the magneto-caloric properties, derived from the Weiss molecular field theory, were adopted for the built-in energy source of the magneto-caloric effect. The numerical simulation was conducted under the conditions of different structural and operational parameters, and the effects of the relative fluid displacement (φ on the specific refrigeration capacity (qref and the Coefficient of Performance (COP were obtained. Besides the variations of entropy, the generation rate and number were studied and the contours of the local entropy generation rate are presented for discussion. From the current work, it is found that with an increase in φ, both the qref and COP followed the convex variation trend, while the entropy generation number (Ns varied concavely. As for the current cases, the maximal qref and COP were equal to 151.2 kW/m3 and 9.11, respectively, while the lowest Ns was the value of 2.4 × 10−4 K−1. However, the optimal φ for the largest qref and COP, and for the lowest Ns, were inconsistent, thus, some compromises need be made in the optimization of magnetic refrigerators.

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.