• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.29 no.9
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• pp.75-78
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• 2000

환경친화적 자동차에 대한 관심이 커질수록 여러 분야에서 시스템 설계의 영향을 더욱 더 잘 이해하려는 노력이 진행되고 있다. 자동차용 냉방기의 경우 냉방시스템의 세밀한 분석과 환경에 미치는 영향을 최소화하기 위한 설계가 이루어지고 있다. 그 중에서도 냉매의 선택과 그 냉매의 환경적 영향에 대한 자세한 연구가 필요하다. 몬트리올 조약 이후 자동차 산업계는 대부분 R-134a를 채택하고 있는데 이는 R-134a가 오존층을 파괴하지 않을 뿐 아니라 적절한 사이클 효율을 가지면서 안전하고 비독성이며 불연성이기 때문이었다. 최근 지구온난화와 이산화탄소($CO_2$)의 발생원에 대한 관심은 산업계가 사용냉매를 재검토하게 하는 계기가 되었으며, R-134a도 교토 조약의 규제냉매에 속해 있어 자동차용 냉방기의 대체냉매에 대한 연구가 시급하다고 여겨지고 있다. R-134a와 관련된 주된 논점은 냉매 누설시의 영향이다. R-134a의 지구온난화지수(GWP)는 1,300인데, 이는 누출되었을 때 1,300배의 이산화탄소가 누출된 것과 동일하다는 것을 의미하다. 최근 자연냉매의 선호와 맞물려 냉매로서 이산화탄소의 평가에 많은 관심이 모아지고 있다. 본 글에서 자동차용 냉방기의 대체냉매로서 이산화탄소의 상대적인 장점과 R-134a와의 비교에 대해 수행된 연구결과를 나타내었다.

• 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.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.11
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• pp.6452-6457
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• 2014

R1234yf has been developed as an alternative refrigerant to R134a, which has been associated with global warming. The capillary tubes as expansion valves control the mass flow rate and balance system pressure in the refrigeration cycle. The present numerical model used the governing equations including the law of conservation of mass, momentum, and energy in a capillary tube. The mass flow rate of R1234yf decreased by 47.0% as the capillary tube length was increased from 1 to 4 m. As the inner diameter of the capillary tubes was changed from 1.3 to 1.7 mm, the mass flow rate of R134a and R1234yf increased by 117.9% and 121.0%, respectively. The mass flow rate of the R134a and R1234yf increased by 28.3% and 29.1% with subcooling increasing from 0 to $7^{\circ}C$. In addition, when the inlet temperature of the capillary tubes was changed from 35 to $60^{\circ}C$, the mass flow rate of R134a and R1234yf increased by 31.0% and 45.4%, respectively.

• Journal of Climate Change Research
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• v.3 no.2
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• pp.153-159
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• 2012

CFC-12 used in mobile air conditioning(MAC) system has been replaced by R-134a, a type of HFC refrigerant, from 1991 to 1994. R-134a has since been widely used as a refrigerant of a mobile air conditioner. However, it is one of the six main green house gases listed in Kyoto Protocol, which makes it imperative to regulate its emission and develop alternative refrigerants. In this study, the concentration of leaked R-134a was measured using VT(Variable Temperature) shed and Running loss test shed to analyze the level of air conditioner refrigerant leaked in a vehicle. According to the analysis of the concentration of R-134a leaked from a vehicle parked, annual leakage amount of R-134a was in the range of 6.46~13.28 g/yr. The figure was similar with the leakage from the mobile air conditioning system currently used. In a study using the same vehicle model, a vehicle equipped with dual evaporation system had a higher leakage rate of refrigerant than a vehicle with a single evaporation system. It appears that the added fittings and joints of the dual evaporator system led to higher leakage rate. Besides, the analysis of the change in R-134a concentration under various car speed found that more refrigerant leaked under high speed(100km/hr) and but the volume of the wind did not affect to the variation of refrigerant leakage.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.9
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• pp.5795-5801
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• 2015

The low temperature distribution of the refrigerated and frozen food has been increased gradually. Refrigeration industry is using R134a refrigerant, which GWP is 1300. R1234yf is an alternative refrigerant of R134a because GWP of R1234yf refrigerant is just 4. Evaporator used in refrigeration truck refrigeration system is operated on low temperature condition. Accordingly, evaporator is formed frost and the formation of frost is rapidly decreased performance of evaporator. In this study, the performance of evaporator using R134a and R1234yf refrigerant was analyzed with operating conditions under frost condition. As a result, the performance of R134a evaporator according to air inlet temperature, relative humidity and evaporating temperature was more sensitive than R1234yf evaporator. Besides, the frost growth of R134a evaporator is steeper than that of R1234yf one.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.6
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• pp.345-352
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• 2010

In this study, external condensation heat transfer coefficients(HTCs) of R134a and R1234yf are measured on a plain, low fin, and Turbo-C tubes at the saturated vapor temperature of $39^{\circ}C$ with the wall subcooling of $3{\sim}8^{\circ}C$. R1234yf is a new alternative refrigerant of low greenhouse warming potential for replacing R134a which is one of the greenhouse gases controlled by Kyoto protocol and is used extensively in mobile air-conditioners. Test results show that the external condensation HTCs of R1234yf are very similar to those of R134a for all three surfaces tested. For the application of condensation heat transfer correlations to the design of condensers charged with R1234yf, thorough property measurements are needed for R1234yf in the near future.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.12
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• pp.837-844
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• 2010

In this study, performance of R1234yf and R1234yf/R134a mixture is measured on a heat pump bench tester in an attempt to substitute R134a used widely in mobile air conditioners (MACs). The bench tester is equipped with a open type compressor providing a nominal capacity of 3.5 kW. All tests are conducted under the summer cooling and winter heating conditions of 7/4 $5^{\circ}C$ and $-7/41^{\circ}C$ in the evaporator and condenser, respectively. For R1234yf/R134a mixture, measurements are made at 5%, 10%, and 15% of R134a by mass. Test results show that the coefficient of performance (COP) and capacity of R1234yf are up to 2.7% and 4.0% lower than those of R134a, respectively. For R1234yf/R134a mixture, the COP and capacity are up to 3.9% lower and 3.6% higher than those of R134a. For R1234yf and R1234yf/R134a mixture, the compressor discharge temperature is $4.1{\sim}6.7^{\circ}C$ lower than that of R134a while the amount of charge is reduced up to 11% as compared to R134a. 90%R1234yf/10%R134a is a better refrigerant than pure R1234yf in that it is less flammable and more compatible with existing R134a system. Based upon the results, it is concluded that R1234yf and R1234yf/R134a mixture are long term environmentally friendly solutions to mobile air-conditioners due to their excellent environmental properties with acceptable performance.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.2
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• pp.109-117
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• 2009

In this study, thermodynamic performance of R430A is examined both numerically and experimentally in an effort to replace HFC134a used in the refrigeration system of domestic water purifiers. Even though HFC134a is used predominantly in such a system these days, it needs to be phased out in the near future in Europe and most of the developed countries due to its high global warming potential. To solve this problem, cycle simulation and experimental measurements are carried out with a new refrigerant mixture of 76%R152a124% R600a using actual domestic water purifiers. This mixture is numbered and listed as R430A by ASHRAE recently. Test results show that the system performance with R430A is greatly influenced by the amount of charge due to the small internal volume of the refrigeration system of the domestic water purifiers. With the optimum amount of charge of 21 to 22 grams, about 50% of HFC134a, the energy consumption of R430A is 13.4% lower than that of HFC 134a. The compressor dome and discharge temperatures and condenser center temperature of R430A are very similar to those of HFC134a at the optimum charge. Overall, R430A, a new long term environmentally safe refrigerant, is a good alternative for HFC134a requiring little change in the refrigeration system of the domestic water purifiers.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.4
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• pp.589-599
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• 1995

The frictional pressure drop of a capillary tube flow is experimentally investigated for pure refrigerants such as R32, R125, and R134a and refrigerant mixtures such as R32/R134a(30/70 by mass percent), R32/R125(60/40), R125/R134a(30/70), and R32/R125/R134a(23/25/52). The binary interaction parameters for the calculation of viscosities of refrigerant mixtures are found based upon the data in the open literature. Several homogeneous flow models predicting the viscosity of two-phase region are compared to select the best model. Cicchitti's equation is known to be the most adequate for the prediction of the viscosity for refrigerant mixtures, which is used in the analysis of adiabatic capillary flows. A model for the prediction of the frictional pressure drop of single and two-phase flow is developed for refrigerant mixtures in this study. This model may be used to design and analyze the performance of a capillary tube in the refrigerating system.

• Journal of Industrial Technology
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• v.20 no.B
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• pp.15-20
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• 2000

High pressure, pressure ratio, refrigerating effect, heat transfer from the condenser and the power of the compressor etc. of a self-made refrigeration equipment for R-12 are investigated when R-12 and R-134a are used as the coolants. The comparison between the performance for R-12 and that for R-134a is made. As a result, R-134a is better than R-12 in the view of high pressure, refrigerating effect and the coefficient of performance and vice versa in the view of pressure ratio, exit gas temperature from the compressor and heat transfer from the condenser.