| Economic and social development has led to increasing demand for energy.To address this problem,global efforts are being made to study new sources of energy and to conserve energy.In recent years,heat pump technology has attracted worldwide attention.Using heat pump technology can save a lot of high grade energy.Different types of heat pump are widely used in industrial and commercial,especially in domestic heating equipment.Heat pump has the function of heating and cooling,so it is suitable for 90% of the world population and region.Air source heat pump generally uses electric drive,uses air as the low temperature heat source,has the characteristic that has no pollutant discharge,is kind of recognized energy-saving environmental protection heating equipment.Here are two main problems in the application of heat pump technology for home heating: first,the low tempratre heating production is not sufficient and the stability is poor.The second is that the heating COP needs to be improved.The level heating of COP is directly determined whether it can be used as a substitute for conventional coal or gas technology.In this paper,a kind of air-source heat pump system with natural cold source is put sub-cooling,and its operation mechanism and design method are studied.Aiming at the heat pump system with R32 as the working medium,the heating performance of natural cold source is adopted to improve its thermal performance.The experimental system was built and studied from the perspective of theory and experiment.Firstly,the attenuation characteristics of heat pump in single-stage compression heat pump are analyzed.Analysis of the compression process,exhaust temperature,throttling process,the influence law of suction superheat on the system,discusses the mechanism of the heat pump efficiency,study the law of various factors to reduce the heat pump heating performance.The natural cold source main sub-cooling and the vapor ejection sub-cooling heat pump system can improve compressor compression process,exhaust temperature and so on,so that the circulation is closer to the quasi-ideal heat pump cycle.Secondly,the thermodynamic analysis model of natural cold source main sub-cooling and the vapor ejection sub-cooling heat pump system is established.This paper analyzes the operation rule of natural cold source main sub-cooling and the vapor ejection sub-cooling heat pump system in improving thermal performance.The system can improve the efficiency and performance coefficient of the compressor and ensure the stability of the unit in low temperature environment.Detailed study of the natural cold source main sub-cooling heat pump heating system,the system uses the natural cold source main sub-cooling system get sub-cooling degree,through the degree of sub-cooling,condensing temperature,evaporating temperature exhaust gas temperature is calculated,system parameters such as heat,power and heating COP change rule;Parts of the vapor ejection sub-cooling system mathematical model is established and verified the model,analyzed the condensing temperature,evaporating temperature,sub-cooling degree will influence the performance of the system,and compared with different circulation pattern.Again,set the main sub-cooling and the vapor ejection sub-cooling system experimental device,experimental research on the key parameters(exhaust temperature,the heating,heating COP,sub-cooling degree and vapor ejection pressure)will affect the performance of the system.The experimental results show that the main sub-cooling system sub-cooling degree increased on exhaust temperature,heat,reduce the heating COP,sub-cooling degree increased 8℃,heating COP by 0.13.To vapor ejection sub-cooled system,exhaust temperature increased too cold,heat,reduce the heating COP,sub-cooling degree increased 8℃,the heating COP by 0.15.Finally,the mechanism of sub-cooling circulation for defrosting system is studied.In this paper,the effect of frost layer on the performance of heat pump system was studied,and the sub-cooling capacity of the frost layer was studied.The relationship between the defrost process and the sub-cooling energy was established,and the study of the defrost system was expounded from the perspective of theoretical analysis. |
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