Development of a micro-channel evaporator model for a CO₂ mobile air-conditioner

This paper presents the development and verification of a heat exchanger model for evaluating thermal performance of an evaporator for a CO2 mobile air-conditioning system. The model has been developed, based on the finite volume method, with emphasis on the air-side heat and mass transfer process. The governing equations are derived from mass and energy balances using newly developed airside heat transfer and friction loss correlations for micro-channel heat exchangers under dry and wet conditions. The calculated air-side heat transfer and pressure drop data are in good agreement with measured data. However, the refrigerant-side pressure drop estimation for micro-channel tubes usually underestimates the measured value. The simulation results and importance of selecting appropriate heat transfer and pressure drop correlations for the micro-channel heat exchanger are addressed.