Research On Simulation Method Of Two-stage Compressed Air Source Heat Pump

Air source heat pump is widely used in our country because of its high efficiency,cleanliness,easy installation,energy saving and environmental protection.However,when the outdoor ambient temperature is too low in winter,the traditional single-stage compressed air source heat pump has the problems of insufficient heating capacity,low heating coefficient,excessively high compressor exhaust temperature and frosting in evaporator during operation.In order to make the air source heat pump work normally in cold areas,researchers have proposed two-stage compression technology and applied it to air source heat pump systems and two-stage compressed air source heat pump products are gradually being promoted and used in cold regions of our country.In the process of product development and equipment debugging of the two-stage compressed air source heat pumps,the traditional method of manufacturing prototypes for repeated debugging will cause a lot of waste of manpower and resources.Therefore,to replace a large number of manual experiments and shorten the product development cycle,we should establish an effective two-stage compressed air source heat pump simulation system with the help of existing computer technology.It not only meets the requirements of energy saving and emission reduction in our country,but also adapts to the development trend of the heat pump air conditioning industry.In this paper,we developed a simulation calculation software for the two-stage compressed air source heat pump system by modeling the two-stage compressed air source heat pump system,and use the software to analyze the heating performance of the system under variable conditions.The research content of this article mainly focuses on the following aspects:In this paper,we establish a steady-state simulation model for a two-stage compressed air source heat pump system with one-stage throttling and incomplete cooling cycle in the middle.We propose the suitable simulation algorithm for each component model and the entire system model: the Variable Integral PID-Bisection method combined control algorithm.And we analyze the determination of the iteration criterion and iteration variables.The heat exchanger is modeled by the partition distributed parameter method,and the mechanism model of the compressor and throttling device is established based on the principle of thermodynamics.The accuracy and calculation speed of the system model are considered.In this study,we use C language to program it based on the established mathematical model of each component to form a modular program,and write dynamic link library file to facilitate the call of main program of different algorithm structure.Then we integrate the component models organically to form a whole system cyclic distributed parameter simulation model based on the Variable Integral PID-Bisection method combined control algorithm.And the simulation model is verified with relevant experimental data.Finally,we use C# to write the simulation software interface,and form a simulation calculation software suitable for the two-stage compressed air source heat pump system.In this paper,the self-developed simulation software is used to simulate the two-stage compressed air source heat pump system under different working conditions,and the operating characteristics of the system under low temperature working conditions are analyzed and discussed.Finally,we obtain the influence law of indoor and outdoor ambient temperature and the front wind speed of the heat exchanger on the system performance.