Numerical Simulation And Experimental Study On Gas Cooler Of The Carbon Dioxide Heat Pump

Based on the shortcomings of the existing HCFC refrigerants,the carbon dioxide that acts as a refrigerant has attracted wide attention and research in recent years because of the fact that the transcritical heat pump unit for the refrigerant has no damage to the ozone layer and has little potential for greenhouse effect,and the heat pump system has high stability and good safety,and has a higher thermal energy efficiency ratio.Domestic carbon dioxide heat pump units are basically concentrated in industrial and commercial large equipments,while its popularity of heating is still at a very low level for small and medium families.So the small carbon dioxide heat pump and experimental research of heat transfer characteristics need to be designed and studied.On the basis of understanding the influence of gas cooler on heat transfer,relevant technical support and reference for the popularization of CO₂ miniaturization applications could be provided in the future.A small family of CO₂ heat pump system was developed in aspect of the theoretical design and practical application,and the main heat transfer components in the system were calculated,and the structure of main equipment were determined,and the experimental schemes were designed based on experiment table.In addition,the numerical simulation of heat transfer inner tube with different structures in gas cooler was carried out by Fluent.One model for horizontal vortex tubes,the causes of the varies of heat transfer coefficient and Grashof number have been analyzed by changing the mass flow rate of the refrigerant and the diameter of the pipe.Another model for twisted helical tubes,The cooling heat transfer performance and change regulation of secondary flow of supercritical CO₂ whose mass flow rate varies have been studied in horizontal elliptical tube whose torque is 100mm or one infinity number,and the influence of axial ratio and torque of twisted elliptical tube on the heat transfer performance has been studied.It has been concluded that the structure of the heat exchange inner tube determines the size of heat exchange in the gas cooler.In this paper,the conclusions that small carbon dioxide heat pumps have been chosen and designed,and numerical simulation has been carried out for different types of internal tubes of gas coolers,will provide a theoretical basis and data reference for further experimental research.