• Solar Energy
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• v.15 no.3
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• pp.75-90
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• 1995

This paper is concerned about alternative refrigerants for HCFC22 used in room air conditioners and heat pumps. Computer simulation of residential air conditioners using refrigerant mixtures is carried out. Following refrigerants are selected as the pure refrigerants constituting the mixtures studied: R32, R124, R125, R134, R134a, R143a and R152a. Simulation results are presented fur the following mixtures: R32/R134a, R32/R152a, R32/R134, R32/R124, R143a/R134a, R143a/R152a, R143a/R124, R125/R134a, R125/R152a, R125/R124, R32/R152a/R134a, R32/R152a/R134, R32/R152a/R124. The best fluid is found to be the ternary mixture of R32/R152a/R124. For that mixture, the coefficient of performance(COP) and volumetric capacity for refrigeration(VCR) are 13.7% larger and 23% smaller than the respective values for HCFC22. R32/R124 mixture is the best binary fluid pair whose COP and VCR are 13.4% larger and 9.6% smaller than those for HCFC22.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.5
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• pp.391-400
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• 2012

In this study, performance of HFC32/HFC152a mixture is measured in the composition range of 20 to 50% R32 with an interval of 10% for the comparison with the conventional HCFC22 in water-source heat pumps. Tests are carried out under the same capacity in a heat pump bench tester equipped with a variable speed compressor at the evaporation and condensation temperatures of 7/$45^{\circ}C$ and -7/$41^{\circ}C$ for summer and winter conditions, respectively. Test results show that the compressor power of the HFC32/HFC152a mixture is 13.7% lower than that of HCFC22 while the coefficient of performance(COP) the HFC32/HFC152a mixture is 15.8% higher than that of HCFC22. Hence, from the view point of energy efficiency, the HFC32/HFC152a mixture is excellent as compared to HCFC22. Compressor discharge temperatures of HFC32/HFC152a mixture are increased up to $15.4^{\circ}C$ as compared to that of HCFC22. The amount of charge for HFC32/HFC152 mixture decrease up to 27% as compared to that of HCFC22. Overall, HFC32/ HFC152a mixture is an excellent long term candidate to replace HCFC22 in water-source heat pumps.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.3
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• pp.292-302
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• 1998

In this study, 14 refrigerant mixtures composed of R32, R125, R134a, R143a, R152a, and R1270(Propylene) were tested in a breadboard heat pump in an attempt to replace R22 used in most of the residential air conditioners and heat pumps. The heat pump was of 1 ton capacity and water was employed as the secondary heat transfer fluids. All tests were conducted under ARI test A condition. Ternary mixtures composed of R32, R125, and R134a were shown to have 4∼5% higher COP and capacity than R22 and hence they seem to be very promising candidates to replace R22. On the other hand, ternary mixtures containing R125, R134a, and R152a have lower COP and capacity than R22. R32/R134a binary mixtures show a 7% increase in COP and have the similar capacity to that of R22 and hence they are also good candidates to replace R22. Special care must be exercised when a suction line heat exchanger is used with these mixtures in air conditioners. Finally, the compressor discharge temperatures of all mixtures tested were lower than those of R22 by 15.g∼34.7t, which indicates that these mixtures would offer better system reliability and longer life time than R22.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.4
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• pp.502-507
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• 2014

In this paper, performance characteristics of cycles were studied when mixed working fluid was used for ocean thermal energy conversion (OTEC). Among the various mixed refrigerants for industrial heat-pump, R32/R152a used in ocean thermal energy conversion system. For simulations, R32/R152a were used in existing closed cycle and Kalina cycle which is used only ammonia and water as mixed refrigerant. Temperature of the warm heat source was 26 and 29 celsius degree, temperature of the cold heat source was 5 celsius degree. In results of simulation, Gross power of the closed cycle on R32 was 22kW, and efficiency of the cycle was 2.02%. When the mixed refrigerant of R32/R152a, in the ratio of 90 to 10, gross power of the closed cycle was 29.93kW, and efficiency of the cycle was 2.78%. Gross power and cycle efficiency of R32/R152a increased by 36% and 37% than those of existing single refrigerant. Additionally, the same simulations were conducted in Kalina cycle with the same various composition ratio of mixed refrigerant.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.8
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• pp.836-842
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• 2013

In this paper, the 20 kW Ocean Thermal Energy Conversion(OTEC) is newly proposed in order to select the refrigerant that makes the cycle performance be optimized and the performance of 20 kW OTEC applying 15 pure refrigerants and 16 mixed refrigerants is analyzed. The efficiency of system, the mass flow of working fluids and TPP, which is new concepts, are analyzed. In view of cycle efficiency, R32/R152a (87:13) is the highest efficiency among the refrigerants. At the mass flow of working fluid to make the 20 kW electricity, R717 is shown as the lowest value. And in view of TPP in this study, R32/R134a 70:30 is the most optimized refrigerant. The analysis can confirm that the refrigerant is different along with the part of the system, so it is necessary to select the optimized refrigerant for 20 kW OTEC.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.4 no.2
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• pp.123-136
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• 1992

A preliminary thermodynamic design model of two-evaporator refrigerator/freezer system is constructed. This system is based on Lorentz-Meutzner cycle using refrigerant mixtures. This model screens alternative refrigerant (R32, R125, R143a, R22, R134a, R152a, R124, R142b, R123) mixtures to select the best performance-giving refrigerant mixtures and its composition for the system. Also, it estimates the effects of cooling temperatures of intercoolers, evaporator's area ratio, cooling load ratio on the performance of the system. The COP of the system ranges from 1.4 to 1.6, which is superior to that of the single evaporator system charged with R12 by 13% to 29%. Among 15 mixtures, R22/R123, R143a/R123, R32/R142b, and R32/R124 (in the order of high COP) are most recommendable. For the case of R22/R123, R22 mass fraction more than 0.5(Load Ratio=1.0) or 0.7(Load Ratio=0.33) is recomended in order to replace R12 without reduction in volumetric capacity when keeping the compressor as the same one. COP has the highest value with X(R22)=0.7 and 0.8, respectively. For the case of R143a/R123, in the similar manner, mass fraction of R143a is more than 0.5 or 0.6 while best performance occurs at X(R143a)=0.8. Higher temperature intercooler is more important for the performance of the system than lower temperature intercooler. The area ratio of evaporators is roughly proportional to load ratio of the evaporators.

• Journal of Power System Engineering
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• v.17 no.6
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• pp.102-107
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• 2013

In this paper, the performance analysis for evaporation capacity, total work and efficiency of the ocean thermal energy conversion(OTEC) power system using mixed refrigerant(R32,R152a) is conducted to find the effect of hot wasted water on OTEC power system. The system in this study is applied with two stage turbine, regenerator, cooler and separator on Organic Rankine Cycle. The commercial program HYSYS is used for the performance analysis. The main results were summarized as follows : The efficiency of the OTEC power cycle has a largely effect on the evaporation capacity and total work. As increasing temperature of heat source water, evaporator's capacity is decreased but total work increase. Otherwise, using hot wasted water bring effects not only increasing system efficiency but also declining evaporator's capacity. Thus With a thorough grasp of these effect, it is necessary to find way to use hot wasted water emitted by power plant and so on.