Experimental investigation on mass flow characteristics of electronic expansion valves with R22, R410A and R407C

A novel model depicting mass flow characteristics of electronic expansion valves (EEVs) is developed based on Bernoulli equation. Different from some conventional models using the two-phase outlet pressure and corrected flow coefficient, the new model considers metastable phenomenon caused by rapid depressurization and employs the pressure at throat of EEVs and the single-phase incompressible flow coefficient. Based on experimental data, a set of empirical correlations for the pressure calculation are developed for R22 and its substitutes, R407C and R410A. The relative deviations of mass flow rate predicted by the present model to the measured data are ranged from −6.12% to +7.50% for R22, and from −9.56% to +9.94% for R410A, and from −13.19% to +16.75% for R407C. The theoretical analyses and predicting results for flow characteristics of EEVs show that the new model is better than other conventional models.