Research on the Flow and Heat Exchange Performance of the Chiller for Electric Vehicles

A set of enthalpy difference test equipment is set up to test flow and heat exchange performance of chillers. The empirical correlations for the convective heat transfer coefficients on the coolant side and the refrigerant side are obtained by fitting the test data, and a two-particle lumped parameter model of the chiller is established. Based on this, the heat exchange performance of the chiller under different operating conditions is given. The effects of herringbone corrugated plate parameters, including angle, pitch, and depth, on flow and heat exchange performance of chillers under different flow rates are further studied. Using the Wilson plot method in test design, the thermal resistance of convective heat transfer on each side is separated from the total thermal resistance to calculate the convective heat transfer coefficient. In fitting the boiling convective heat transfer coefficient on the refrigerant side, various boiling behaviours within the two-phase zone are considered, and critical value distinguishing dominant boiling behaviours is quantitatively determined. In the modelling of chillers, two-phase and overheated zones of the refrigerant are considered simultaneously, and their area sizes are calculated to enhance the accuracy of the model. The study on the influence of chiller structural parameters on flow and heat exchange performance shows that within a certain range, the chevron angle is positively correlated with pressure drop and Nu, while the chevron pitch and depth are negatively correlated with pressure drop and Nu. As Reeq increases, the correlations between pressure drop and structural parameters become more significant. Insights on chiller design can be gained from this study.