R1234yf와 R1234yf/R134a의 자동차 에어컨 작동 조건에서의 성능 평가

박기정(Ki-Jung Park),이요한(Yohan Lee),최대성(Daeseong Choe),정동수(Dongsoo Jung) 대한설비공학회 2010 설비공학 논문집 Vol.22 No.12

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 ㎾. All tests are conducted under the summer cooling and winter heating conditions of 7/4 5℃ and -7/41℃ 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 4.1~6.7℃ 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.

냉매 R1234yf의 모세관내 유동 특성에 관한 해석적 연구

김대영(Kim, Daeyeong),박차식(Park, Cha-Sik) 한국산학기술학회 2014 한국산학기술학회논문지 Vol.15 No.11

최근에 지구온난화 문제로 인하여 R134a 냉매에 대한 규제가 강화되면서 대체냉매로서 R1234yf 냉매가 개발되었다. 냉동사이클에서 팽창장치인 모세관은 유량제어와 압력조절의 역할을 한다. 본 연구에서는 모세관에 흐르는 냉매유동의 지배 방정식을 사용하여 R134a와 R1234yf 냉매에 대하여 해석적 연구를 수행하였다. 모세관 길이를 1-4 m로 변화시켰을 때 R1234yf 냉매의 질량유량은 47.0% 감소하였다. 모세관의 직경을 1.3-1.5 mm로 변화시켰을 때 R134a 냉매와 R1234yf 냉매의 질량유량은 각각 117.9%와 121.0% 증가하였다. 모세관 입구의 과냉도를 0-7℃ 변화시켰을 때 R134a 냉매와 R1234yf 냉매의 질량유량은 28.3%와 29.1% 증가하는 것으로 나타내었고, 모세관 입구에서 운전조건을 35-60℃로 변화시켰을 때 R134a 냉매 는 31.0%, R1234yf 냉매는 45.4% 증가를 각각 나타내었다. 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℃. In addition, when the inlet temperature of the capillary tubes was changed from 35 to 60℃, the mass flow rate of R134a and R1234yf increased by 31.0% and 45.4%, respectively.

R134a와 R1234yf 냉매 적용에 따른 냉동탑차 냉장시스템의 성능비교

신윤찬 ( Yunchan Shin ),김진현 ( Jinhyun Kim ),조홍현 ( Honghyun Cho ) 조선대학교 공학기술연구원 2017 공학기술논문지 Vol.10 No.2

Recently, the importance of delivery system has being developed according to the growth of online and mobile shopping market. Especially, transportation of frozen food by online and home shopping is increasing significantly. Therefore, the demand of refrigeration truck is also increasing. In this study, performance characteristics of refrigeration system using R134a and R1234yf in a refrigeration truck were compared by experimental method. When the refrigerant charging amounts increased from 1.1 to 1.4 kg, COP of R134a system was increased and the maximum COP was 2.63 at the charge amount of 1.4 kg. And that of R1234yf system was 2.49 at the optimal charge amount of 1.3 kg. The optimal EEV opening of R134a and R1234yf system was 60% and 50%, respectively. Besides, the COP was 2.69 and 2.49 for R134a and R1234yf at the optimal EEV opening. When the outdoor air temperature increased from 25℃ to 35℃, the system COP of R134a and R1234yf decreased by 15.0% and 11.6%, respectively. Besides, When the compressor rotating speed increased from 1000 to 2000 rpm, the system COP of R134a and R1234yf decreased by 37.5% and 35.9%, respectively. The R134a system showed a higher performance than R1234yf system, but the R134a system showed the larger reduction in the performance according to compressor rotating speed.

냉매 R1234yf 적용 자동차용 에어컨 Drop-in 성능 특성

조홍현(Honghyun Cho),이호성(Hoseong Lee),박차식(Chasik Park) 대한설비공학회 2012 설비공학 논문집 Vol.24 No.12

In this study, the performance of mobile air conditioner(MAC) systems to which the refrigerants R134a and R1234yf were used was evaluated to compare the characteristic of automotive refrigeration cycles with refrigerant. The experimental setup of a MAC consists of an belt driven compressor, a condenser, an evaporator and a block type thermal expansion valve. The drop-in test on MAC were carried out under variable compressor speed from 800 to 2500 rpm. Performance test by using R1234yf and R134a in the same system revealed low the charge amount and mass flow rates for using R1234yf, that is, up to 10% and 17%, respectively. The compressor discharge temperature of R1234yf is 8℃ lower than that of R134a. The cooling capacity with R1234yf system decreased by 4~7% compared with R134a system. In addition, The COP of R1234yf system is lower 3~4% than that of R134a system.

착상조건에서 R134a와 R1234yf를 적용한 핀-관 형태의 증발기 성능 비교

신윤찬(Shin, Yunchan),김진현(Kim, Jin-Hyun),조홍현(Cho, Hong-Hyun) 한국산학기술학회 2015 한국산학기술학회논문지 Vol.16 No.9

식생활의 향상 및 다양화로 신선한 제품에 대한 요구가 증가하고 있으며, 이에 따라 냉장 및 냉동식품의 저온유통 또한 점차 증가되고 있다. 현재 냉동산업에는 주로 R134a 냉매가 사용되고 있으며 GWP(Global Warming Potential)가 1300으 로써 매우 높아 지구온난화에 영향을 미친다. 이를 대체하기 위한 냉매로써 R1234yf 냉매가 있으며, GWP는 4로써 매우 낮 다. 냉동탑차 냉장시스템에 사용되는 증발기는 저온조건에서 작동되기 때문에 서리가 형성되어 시스템의 성능을 급격히 감 소시킨다. 따라서, 본 연구에서 R134a와 R1234yf 냉매를 작동유체로 사용한 증발기의 성능을 착상조건 하에서 다양한 운전 조건으로 분석하였다. 해석결과, 서리성장 조건에서 공기측 입구온도, 상대습도, 증발온도 변화에 대하여 R134a 증발기의 성능이 R1234yf 증발기보다 더욱 민감하게 나타났으며 서리의 성장 또한 R134a 증발기가 더 크게 나타났다. 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.

냉매 R1234yf/R1234ze/R152a에 대한 이젝터 적용 냉동사이클의 성능 향상에 관한 연구

박차식(Cha Sik Park) 호서대학교 공업기술연구소 2015 공업기술연구 논문집 Vol.34 No.1

본 연구는 이젝터를 팽창장치로 적용하여 대체냉매에 대한 냉동사이클의 성능향상을 해석적으로 분석하였다. 이젝터 내부의 유동을 연속방정식, 에너지방정식. 그리고 운동량방정식을 이용한 이론식을 모델링하여 해석을 실시하였 다. 해석결과를 통하여 이젝터 적용 냉동사이클의 성능향상은 냉매 R1234yf가 가장 높게 나타났고, R152a가 가장 낮게 나타났다. 또한 증발온도와 응축온도의 차가 증가하는 가혹한 운전 조건일수록 이젝터 냉방사이클의 성능 향상효과가 크게 나타났다. 이젝터 디퓨져의 성능 변화에 대한 영향은 R1234yf 냉매가 가장 크게 나타났다. This paper presents a numerical study on the performance of refrigeration cycle equipped with an eiector using alternative remgerants. The simulation is carried out using the model based on the conservation of mass, energy and momentum in the ejector. Based on the results of simulation, the COP improvements of R1234yf system is highest, Pereas that of R152a system is lowest when the ejector refrigeration cycle is applied. The ejector refrigeration system represents the more irrqjroved effects with the increase of the temperature difference between condensing and evaporating. In addition, the efticiency of the ejector diffuse has an greatest effect on the performance of R1234yf system.

관경 변화에 따른 R-1234yf의 증발 압력강하에 관한 실험적 연구

윤정인(JungIn Yoon),설성훈(SungHoon Seol),이준혁(JoonHyuk Lee),박은민(EunMin Park),하수정(SooJeong Ha) 한국산학기술학회 2021 한국산학기술학회논문지 Vol.22 No.11

HFC계 냉매인 R-134a는 GWP가 높아 환경 문제를 일으키고 있으므로 이를 대체하여 열역학적 특성이 유사하고 GWP가 낮은 HFO계 냉매 R-1234yf를 연구하고자 한다. 그러나 R-1234yf에 대한 실험적 연구는 매우 부족한 실정이다. 따라서, 우리는 R-1234yf의 증발 압력강하 메커니즘을 명확하게 규명하기 위해 연구가 필요하다고 생각했다. 실험조건은 질량유속 200~500 kg/㎡s, 열유속 5~10 kW/㎡, 포화온도 5~15°C 및 관경 3.7~6.8 mm이다. 압력강하는 포화온도가 증가함에 따라 감소한다. 밀도 및 점도계수비가 각각 27, 15%씩 감소하기 때문이다. 또한, 압력강하는 열유속이 증가함에 따라 증가하는 경향이 있다. 이는 모든 관경에 대해 질량 유량이 클수록 압력강하가 커지며, 낮은 건도보다 높은 건도에서 압력강하가 증가한다는 것을 보여준다. 관경은 감소할수록 압력강하가 증가하였다. 내경 3.7~6.8 mm관 내 R-1234yf의 증발 압력강하를 타 상관식으로 예측한 값을 비교한 결과 각 평균오차 –15.3%, -21.3%로 좋은 일치를 보였다. The HFC refrigerant R-134a has a high GWP and causes environmental problems. Hence, we intend to replace it with the HFO refrigerant R-1234yf with similar thermodynamic properties and a low GWP. However, experimental studies on R-1234yf are very scarce. Therefore, research is needed to clearly elucidate the mechanism of evaporation pressure drop of R-1234yf. The experimental conditions for the present study were a mass flow rate of 200~500 kg/㎡s, a heat flux of 5~10 kW/㎡, a saturation temperature of 5~15°C, and a diameter of 3.7~6.8 mm. From the experiments, we observed that the pressure drop decreases as the saturation temperature increases. This is because the density and viscosity coefficient ratio decrease by 27 and 15%, respectively. The pressure drop also tends to increase with an increasing heat flux. This shows that for all pipe diameters, the greater the mass flow rate, the greater the pressure drop. The pressure drop also increases at higher vapor quality than at lower vapor quality. Moreover, as the pipe diameter decreased, the pressure drop increased. As a result of comparing the values predicted by other correlation formulas for the evaporation pressure drop of R-1234yf in pipes with inner diameter 3.7~6.8 mm, the average error was -15.3% and -21.3%, respectively, showing good agreement.

압축기 회전수 변화에 따른 R134a/R1234yf 혼합냉매를 적용한 자동차 공조 시스템의 성능 특성에 대한 해석적 연구

김태중(Tae-Jung Kim) 한국산업기술융합학회(구. 산업기술교육훈련학회) 2021 산업기술연구논문지 (JITR) Vol.26 No.3

This study presents the performance analysis for an automobile air-conditioning system using the mixed refrigerant R134a/R1234yf with varying compressor rotation speeds. Accordingly, the compressor, condenser, expansion device, and evaporator of the automobile air-conditioning system were designed using the EES program, and the cooling capacity and COP of the automobile air-conditioning system using the mixed refrigerant were comparatively analyzed for simulated data. The cooling capacity using the mixed R134a/R1234yf(30%) system at a compressor rotation speed of 2500 rpm was about 6.13% lower than that using the R134a system alone. Moreover, the COP using the mixed R134a/R1234yf(30%) system at a compressor rotation speed of 2500 rpm was about 7.45% lower than that using the R134a system alone. The use of the R134a /R1234yf mixed refrigerant can thus reduce global warming potential; further, as there is no significant difference in performance compared with the system using only R134a, the applicability of the mixed R134a/R1234yf refrigerant is confirmed.

R134a와 R1234yf 냉매 적용에 따른 냉동탑차 냉장시스템 성능비교

강우빈(Woobin Kang),신윤찬(yunchan Shin),조홍현(Honghyun Cho) 대한설비공학회 2016 대한설비공학회 학술발표대회논문집 Vol.2016 No.11

Performance evaluation of low global warming potential working fluids as R134a alternatives for two-stage centrifugal chiller applications

Gang Li 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.7

With the increasing concern about climate change, the Kigali Amendment to the Montreal protocol requires parties to gradually reduce high global warming potential (GWP) hydrofluorocarbon (HFC) use by 80-85% by the late 2040s. The US Environmental Protection Agency (EPA) and EU Directive 517/2014 are also setting the ban on the use of such refrigerants. R134a, as a high GWP (GWP100:1300) HFC refrigerant, is a commonly used medium pressure chiller refrigerant that will be phased out. Searching for low GWP R134a alternatives is necessary. In this study, hydrofluoroolefin blends-R513A, R513B, R515A, R515B, R516A and pure hydrofluoroolefins-R1234yf and R1234ze(E) are investigated for performance evaluation for two-stage centrifugal chiller application with a fixed cooling capacity 1,750kW. The evaluation was conducted via a thermodynamic process model, a component sizing methodology and a life cycle environmental performance methodology. R515A, R515B and R1234ze(E) show a 25% volume capacity reduction in comparison with baseline due to their low suction density. All R134a alternatives exhibit more component heat transfer area than baseline, with 5-15% increase for the evaporator and 12-38% for the condenser. The comparison for the compressor impeller diameter shows that R513A, R513B, and R516A do not require the compressor size change from baseline, while R515A, R515B and R1234ze(E) need a more than 18% larger compressor size. R134a alternatives can provide 8.4-16.7% life cycle emission reduction in China and 14.7-27.7% in South Korea. In general, R513A, R513B and R516A are more preferable R134a drop-in options for less component modification and the same compressor can be employed directly. R516A is A2L and necessary vessel safety code protection is needed. R515A and R515B can serve as the system newly design-based interim non-flammable replacement for R134a in medium-pressure chillers with a large modification for a compressor. Gradually, with more strict regulations, R1234ze(E) can be the ultimate option in the market with less/negligible modification from R515A and R515B. For R1234yf, its poor heat transfer performance and high price can impede its application in chillers. It is anticipated that the viewpoints and insights from this study can be beneficial for the engineers, policymakers, scholars, public and manufacturers to maintain the maximum sustainability and economic benefits.