Dynamic simulation of electronic expansion valve controlled refrigeration system under different heat transfer conditions

This work presents a new dynamic lumped parameter model that is able to simulate the oscillation of electronic expansion valve (EEV) controlled refrigeration system due to unsuitable control or abrupt change of external parameters. Based on bubble dynamics theory, the heat transfer characteristic is used to divide the evaporator into the stable and unstable conditions, and a matching switch criteria is presented. Together with the model of main components, the dynamic behavior of oscillation of system parameters is simulated successfully. Model validation against experimental data demonstrates the capabilities of the modeling approach in predicting the instability of system control loop. This study provides the basis for further developing advanced control algorithm which will ensure that an EEV-controlled system refrigeration system has better stability.