자동차용 공기조화기의 부분부하 운전특성에 관한 실험적 연구

Abstract

Operating characteristic of an air conditioning system for vehicle is dynamic and anomalous. Due to the dynamic behavior of the system, the performance measurement should be taken in account in many different kind of environmental condition with various thermodynamic variables. One of the driving condition of the system, rotating speed of the compressor for air conditioning is the most important factor consideration that is directly connected to the vehicle engine through clutch and belt. The engine was simulated with 18.5KW class AC motor to drive the compressor. The study was conducted to get performance information at various driving condition of the vehicle. The experiments was performed in 3 driving mode (Idling, Intermediate and Highway speed) on the same compartment temperature condition and changing inlet air temperature and air flow rate passing through the outdoor heat exchanger. For the cyclic operation of the system in the mobile air conditioning system, the on/off operation of the blower fan of the indoor heat exchanger was conducted to know about the effect of the heat release during the off period of the compressor. As results, cooling capacity decreased a little in steady state with reducing the outdoor temperature however the power consumption of the system increased significantly. This is due to high specific volume of the circulating refrigerants in the suction line of the compressor by overheating of the refrigerant. In the experiment for the on and off operation of the blower fan in the compartment heat exchanger, the delay time of the system was reduce more that continuous operation of the fan. Changing the driving speed of the vehicle yields the variation of the compressor speed. The test for the variation of the compressor was conducted in 3 kinds of operation mode with Idling(900rpm), Intermediate (1800rpm) and Highway(2500rpm) speed. Each mode showed similar level of cooling capacity, however, power consumption show a considerable different. System efficiency is highest at idling-mode.