Study On Heat Transfer Characteristics Of Gas Cooler Based On 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 inindustrial 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 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 is the horizontal straight pipe.By changing the mass flow rate and inlet temperature of the refrigerant,the variation of its temperature field and heat transfer coefficient and the reasons for the change are analyzed.The other model is the horizontal spiral pipe,which studies the influence of different structural parameters（pipe diameter,pitch）and the presence or absence of gravity on supercritical CO₂ heat transfer characteristics and rules.The influence of structure parameters,water inlet temperature and refrigerant mass flow rate on the heat transfer performance of the gas cooler was studied,and the law of the heat transfer performance of the gas cooler changing with the structure was summarized.In this paper,the conclusions that 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.