흡착제를 이용한 자동차용 예냉시스템의 구현방안에 관한 연구

Abstract

The study was conducted to evaluate operation characteristics of pre-cooling system for the vehicles. The system was three modes which is refrigeration cycle, pre-cooling cycle and recovery cycle. The pre-cooling system applied an adsorption tank to make driving force of the refrigerant in the system during start up process which state the compressor does not working. The adsorption tank, filled with silica-gel, was located between evaporator and compressor. During the instantaneous process, the refrigerant in the high pressure side flows through the expansion valve and make cooling effect at the evaporator and adsorbed to the silica-gel in the adsorption tank. At that time, the pressure in the adsorption tank is increased slowly and reached the equilibrium pressure between low side and high side pressure in the refrigeration cycle. In the recovery cycle, hot water, extracted from radiator of the vehicle, supplied to the silica-gel tank and take out the refrigerant in the adsorption tank. The water is 70℃ and pump-down technique was applied to increase desorption rate. Type 1 of pre-cooling system has a receiver tank which is located outlet of condenser. Main purpose of receiver tank is store of refrigerants. So Refrigerants, stored in receiver tank, are used to pre-cooling system. During the pre-cooling cycle, outdoor temperature is 35℃, indoor temperature is 40℃ and air flow is 8㎠ /min. As a result of experimental, refrigerant in the receiver tank were not flowed. At the type 2 of instantaneous system, Receiver tank was removed because refrigerant, stored in the receiver tank, are not flowed according to pressure difference. During the refrigeration cycle outdoor conditions are 27℃ and air flow 48㎠ /min, indoor temperature is 35℃ and air flow is 8㎠ /min. At the pre-cooling cycle, outdoor temperature is 35℃, indoor temperature is 40℃ and air flow is 8㎠ /min. At first, experimental which is making a driving force was conducted. As a result silica-gel in the adsorption tank made a driving force. According to driving force, refrigerant was flowed in the pre-cooling system. During the pre-cooling cycle, pressure and temperature in the adsorption tank was increased because of adsorption of refrigerant. Commonly, the adsorption process cause exothermic reaction. To recovery of silica-gel, radiator simulator supplies adsorption tank with hot water of 75 temperature and temperature of adsorption tank was increased to 65℃. After then, pump down was conducted to collect of refrigerant which is desorption in the adsorption tank. To adsorption chiller supplies adsorption tank with cooling water of 4℃ and temperature of adsorption tank was decreased to 13℃. Because adsorption rate of low temperature is higher than high temperature. As a results, desorption process needs to hot water which is 75℃ and adsorption process needs to cooling water. This system has a serious problem that pump oil was flowed in adsorption tank and didn't return to system. So pressure of compressor is increased to 73kg/cm2. At the moment the compressor was broken. Conclusively system must be revision to protect the compressor. At the type 3 of pre-cooling system has resolved the problems which are find out at the advanced research. Because compressor doesn't working at the pre-cooling cycle, consumption of blower fan of evaporator was used to calculation of COP. An experimental was conducted to find a pre-cooling system with variation of temperature of adsorption tank. as a results, COP was 4.1 at the 13℃ and was 2.8 at the 23℃. COP of low temperature is more higher than high temperature. After experimental was conducted to find a pre-cooling cycle with a variation of pressure of evaporator. as a results, time of pre-cooling cycle was 13minutes, cooling capacity was 1.6kw and COP was 2.42 at the low pressure of evaporator. On the contrary to this, time of pre-cooling cycle was 7minutes, cooling capacity was 2.5kW and COP was 3.84. On the analyzed results, this state match up with general adsorption characteristics that adsorption rate is increased at the high pressure and low temperature.