Theoretical Analysis And Performance Study Of Enhanced Vapor Injection Cascade Air Source Heat Pump

Aiming at the applicability of air source heat pump in low temperature environment,an enhanced vapor injection cascade air source heat pump which can adapt to the efficient and stable operation in northern winter is proposed in this paper.The low-temperature stage of the enhanced vapor injection cascade air source heat pump takes R410 A / R134 a as the circulating working medium,and the innovative combination of the enhanced vapor injection system and the cascade heat pump system overcomes the disadvantages of the traditional air source heat pump,such as high requirements for ambient temperature,low cop,large compressor pressure ratio,high exhaust temperature and low heat production.The main research contents are as follows:(1)According to the cycle principle of the heat pump system,the pressure enthalpy diagram and thermodynamic law of the working medium of the system,the thermodynamic model of the heat pump system is established,the effects of different evaporation and condensation temperatures and vapor injection ratio on the system are analyzed,and thermodynamic analysis are simulated to provide a theoretical basis for the design of the experimental prototype of the system;(2)According to the set working conditions of the equipment,the components of the system are selected,and then the experimental prototype is formed by the assembly of the system components.The mathematical models of the system components are established and solved respectively.The reliability of the model is obtained by comparing the simulation data with the test results of the experimental prototype.At the same time,the influence on the system performance with or without enhanced vapor injection is simulated;(3)Simulate the system performance of single-stage operation and cascade operation under different working conditions,analyze the influence of compressor frequency and ambient temperature on system heating capacity,power,cop,exhaust temperature and other parameters,and compare the performance of single-stage operation and cascade operation.