Research And Design Of HG-45B Environment Control Equipment Worked Over A Wide Temperature Range

The application of non-azeotropic mixtures in refrigeration systems broadens the temperature range of environmental control devices. Also, it provides a possible way to solve the decline of cooling capacity and exaltation of discharge temperature of the compressor at high temperature. The non-azeotropic mixture is consisted of middle and high refrigerants, which is different from the pure refrigerant because of its characteristics of temperature glide in the phase change processes. This special characteristics help to reduce the heat transfer temperature difference and the irreversibility, and improve the efficiency of refrigeration systems.In the second chapter, we calculate the thermodynamic property of R22&R142b under different mass fraction by RefProp8.0software. We also simulate some important thermal-physical parameters change of refrigeration cycle under fixed mass fraction and different working condition. In this chapter, the process of heat transfer in heat exchanger is analyzed. The results of R22&R142b provide a good suggestion for experimental study of the mixture filling ratio in cycle system and type determination of heat exchanger.After calculation and comparison between actual heat transfer areas of HLD-45b evaporator and required ones at the design condition, we find that there is still a large room for cooling capacity improvement. We also re-match the expansion valve for the new designed evaporator. The appropriate thermodynamic models are selected for different refrigerant mixtures. And the refrigerant charge capacities of main components and the distribution ratio are given using discrete calculation.In chapter4, we study the variation trend of main thermodynamic properties in system by the experimental contrast between HLD-45b and HG-45b under the same conditions. The results showed that the refrigerating capacity of HG-45b increases about10%than the former, since its evaporator heat exchange area is increased. The temperature measured of different parts indicated that the increase of evaporator heat exchange area can enhance the evaporating temperature. Accordingly, evaporating pressure is increased and compress ratio is decreased. These results also showed that the compressor power reduced about5%. The discharge temperature and pressure of compressor are reduced, which is helpful for the efficiency improvement of the compressor working at high-temperature. This is important for the indoor temperature control and ensuring the stable operation of the compressor. The proper adjustment of the fan delivery reduces the heat transfer temperature difference between the air and the refrigerant. So the irreversible loss of the whole cycle is decreased. Based on our study, the energy efficiency of our re-designed environmental control device increased by about14.5%compared with its former counterpart.