Measurement and control system by electronic expansion valve for refrigeration performance test

ZHOU Hai-liang， JIANG Zhou-shu， DING Qiang
（College of Automation， Hangzhou Dianzi University， Hangzhou 310018， China）

Abstract： Aiming at the problems that the coolant temperature control by temperature control instrument has a large overshoot and stable state error while compressor performance test through the second fluid calorimeter method，an electronic expansion valve control system which can be carried out exploratory experiment was developed. Electromagnetic type electronic expansion valve instead of the thermal expansion valve was used to give a high-precision control. Temperature and pressure of multiple state points in the system were real-time collected to realize the temperature intelligent control of the calorimeter in the refrigeration system. After the elaboration of the system's working principle，the measurement and control model were established. The temperature and pressure alarm mechanism were taken to realize the stable operation of the system. The supporting software by using the object-oriented design method was developed，on the .Net development platform，the integral separation PID controls module was especially designed. Multiple control experiments were taken and compared with other control method. The results indicate that using an electronic expansion valve as a control actuator is advantageous to reduce the overshoot and keep stability.
Key words： electronic expansion valve； measurement and control system； proportion-integral-derivative（PID）control； refrigeration performance test