Research And Emluator Of Gas Cooler In Transcritical Carbon Dioxide Mobile Air-Condition

The interest in the transcritical carbon dioxide cycle has greatly increased among natural refrigerants in the world since its appearance. Lots of theoretical analysis and experimental studies have shown that the transcritical carbon dioxide cycle has a wider future, but also have some difficulties to conquer. This study principally probes into the heat transfer of supercritical carbon dioxide flowing in heat transfer of car air-condition with numerical simulation. The major accomplishments are summarized as follows:1. The main effects to supercritical carbon dioxide heat transfer are analyzed, including pressure, mass flux, flow direction, diameter and buoyancy, lubricating oil, heat flux effect factors and so on. The deeper analysis of effect factors of heat transfer is summed up that specific heat and the thermophysical properties of carbon dioxide in boundary layer caused the dramatically change of heat transfer.2. The convection heat transfer of carbon dioxide in mini tube has been emulated. The effects of the parameters on the heat transfer of supercritical CO₂ were analyzed. Finally, the way to improve heat transfer has been advised.3. A model was developed for micro—channel gas coolers in transcritical carbon dioxide refrigeration systems. Fluid flow and heat transfer processes in both refrigerant and air sides were analyzed with the latest physical properties database and the corresponding correlations. The model was validated by the comparison between simulation results and experimental data under various conditions. Furthermore , the influences of major parameters on gas cooler performance were analyzed and discussed. So the above parameters should be considered comprehensively in the optimal design of gas cooler. The model developed in this paper could be used for the optimal design of gas coolers.