대체냉매 적용 상용탑차용 냉동시스템 성능연구

Abstract

The request for the high quality has been increased because of the improvement of the dietary life and diversification. The refrigeration vehicle equipped with a refrigerator for the long and short distances transportation of this food is widely used. CFCs are used in the existing refrigeration truck because of stabilized chemistry and excellent thermodynamic properties. However, in the 1970s, it was regulated in the Montreal Protocol because of destroying the ozone layer of the stratosphere. HCFC refrigerant as the substitute refrigerant of CFC refrigerant was used in the cryogenic freezing industry. Using the HCFC refrigerant is globally limited because it would destroy the ozone layer and lead to global warming. Since, the scale of new cars which equipped with refrigerant over GWP 150 is under the anticipation, GWP of the R404A and R134a refrigerant are higher than the standard value. In order to solve these problems, the research of alternative refrigerant has actively carried out. In this study, Refrigeration truck refrigeration system applying the R404A and R134a was conducted experimentally and analytically studies. As the indoor side air temperature rose from 5℃ to 9℃, the COP of R404A and R134a system increased. As the indoor side air temperature rose from 25℃ to 35℃, the COP of R404A and R134a system decreased. With the increase of time and indoor air temperature's change, COP decrease of R404A system is larger than that of R134a system. With the increase of time and outdoor air temperature's change, COP decrease of R404A sytyem is larger than that of R134a system. With the increase of time and compressor rotating speed's change, COP decrease of R404A sytyem is larger than that of R134a system. In various operating conditions, R404A system was more sensitive than R134a system. A model of commercial truck refrigeration cycle applying R744 and R1234yf as a alternative refrigerant was established and analytical study was conducted in various operating conditions. The COP increasing rate of the R134a and R1234yf system is bigger than the R404A and R744 system as the indoor temperature increased. The COP decreasing rate of the R404A and R744 system is bigger than the R134a and R1234yf system as the outdoor temperature increased. As the outdoor air velocity increased, the COP increased rapidly to 2m/s, and then the COP increasing rate was small due to enough heat exchange in the condenser. As the compressor rotating speed increased, the COP of every system decreased.