Optimization of zero superheat control at the evaporator outlet: Application of EXV and pressure regulation valve

Zero superheat degree at the outlet of the evaporator is important for the efficient operation of refrigeration systems. Though it is the theoretically possible to control zero superheat degree to zero, it is rare to find publications in this area. In this study, the effects of the electronic expansion valve and the pressure regulation valve on zero superheat control investigated experimentally. The results indicate that when the control value of degree was set to zero, the electronic expansion valve could not achieve accurate control. The evaporation pressure and temperature kept changing, and the refrigerant flow state at the outlet of the evaporator alternated dramatically at the same time. There was a significant appearance of liquid refrigerant at the evaporator outlet. However, the stable control of zero superheat could be achieved when using the Electronic Expansion Valve and Pressure Regulation Valve Common Control Method (EPCCM). The combination of the pressure regulation valve and the Electronic Expansion Valve enables independent control of the evaporation pressure and the superheat degree at the outlet of the evaporator, which makes it possible to control the superheat of the refrigerant at the outlet of the evaporator to zero. The experiment results also show that the EPCCM has remarkable effect on zero superheat control, as well as safe and stable operation of the refrigeration systems.