Mass flow characteristics and empirical modeling of R744 flow through electronic expansion device.

Electronic expansion valve (EEV) takes advantages of its fast response, wide working range and accurate control and is been widely used in CO 2 heat pump and air-conditioning system while the CO 2 mass flow characteristics is the most crucial parameter for EEV. Different from other refrigerants, at the inlet of EEV, CO 2 maintains at supercritical state. In this study, the effects of inlet pressure, inlet temperature, outlet pressure, EEV flowing area and EEV geometries on CO 2 mass flowing through EEVs have been investigated under a wide operation range for three different EEVs. Meanwhile, a new empirical correlation has been developed to predict the mass flow rate of CO 2 flowing through EEVs based on the experimental data. The proposed dimensionless correlation shows a good agreement with the test data. Approximately 91.8% of the experimental data within a relative deviation of ±5% for all EEVs. The average deviation and standard deviation of the predictions are 0.36% and 1.93% respectively. [ABSTRACT FROM AUTHOR]