Study On The Key Technology Of Air-source Heat Pump System In The Condition Of Low Temperature And High Humidity

Air source heat pump has been widely application in our country, but there aremany problems in low temperature and humidity environment, such as: exhausttemperature is too high, the heat significant attenuation, frost, etc.Firstly, through analyzing the cause of the problem, at the same time, consideringthe advantages and disadvantages of the traditional defrosting method, a couplingsub-cooler vapor injection air source heat pump system was proposed. The systemconsisted of two sub-cooler vapor injection air source heat pump by two triple tube heatexchanger, the defrost method was system coupling defrost based on the traditional hotgas bypass defrost, liquid refrigerant evaporation problem was solved which the outdoorheat exchanger produced when traditional hot gas bypass defrost, the problem ofcompressor liquid impact was avoided, the operation reliability of air source heat pumpin low temperature high humidity environment was improved. The content of researchhas high academic value and wind application prospect.Secondly, the circulation process structure and thermodynamic calculation modelof new system was introduced. Through the calculation of theoretical assumptions, thetotal coefficient of performance of new system was much higher than traditionalsub-cooler vapor injection air source heat pump system, and the new system featureswas analyzed.Thirdly, refrigerant thermal properties calculation software was developed withMicrosoft Visual C++6.0integrated development environment, and established thesystem thermodynamic calculation model to call refrigerant thermal propertiescalculation module, the new system in normal heating condition was stimulated andoptimized, the optimal medium temperature and corresponding injection ratio in lowtemperature environment was achieved. According to the optimal medium temperaturesunder different conditions of the new system, a binary linear fitting formula of optimalmedium temperature from condensing temperature and evaporating temperature was gotthrough the Matlab software. And the fitting formula was achieved.Finally, the influence of triple tube heat exchanger on new system was analysed,include the role of triple tube heat exchanger in new system, and the influence of tripletube heat exchanger on new system’s performance in normal heating condition. Thefluid field of assumptive triple tube heat exchanger was simulated and calculated, the triple tube heat exchanger of new system could be optimized by joining spiral chip andbaffle plate...