Control method of evaporation temperature in small refrigeration compressor of performance test system

FENG Chun-song， GU Jiang-ping， XV Ming， HUANG Yue-jin
（College of Mechanical Engineering， Zhejiang University of Technology， Hangzhou 310014， China）

Abstract： Traditional control method of the evaporation temperature is poor accurate and the temperature has large fluctuations in the small refrigeration compressor of the performance test system. The control of the evaporation temperature is controlled accurately or not which is directly related to the measurement accuracy of the cooling capacity. In order to accurately measure the cooling capacity，the evaporation temperature needs to be controlled accurately. In the experiment，the suction pressure corresponding evaporation temperature was selected as the controlled object and was based on the target's condition，with the understanding of the principles of control for evaporation temperature；the hardware platform and the pulse generator was built and controller and the corresponding control program are designed for it；the control of the PID control was selected as the control strategy，communication protocols were designed，so the evaporation temperature can be controlled by the software of the computer in time；the reasonable response time and the ideal control parameters can be drawn by experiment. The results indicate that the PID control of the evaporation temperature which can achieve the automatic adjustment of the expansion valve，can improve the control accuracy of the system and the control of the evaporator temperature can be more precise and stable.
Key words：compressor； temperature control； refrigeration； evaporation temperature； PID