Study On Absorption-ejection Refrigeration Cycle And Boiling Heat Transfer Based On R290-POE

Absorption refrigeration technology has advantages in the utilization of low-grade energy and environmental protection,and the properties of refrigeration working pair directly affect the performance of the absorption refrigeration system.Compared with other working pairs,R290-POE solution has a wide working range,low generating temperature,non-crystallizable,no corrosion to metals,and has broad development prospects.Firstly,the single-effect absorption refrigeration system is optimized,and the absorptionejection compound refrigeration system is formed by adding an ejector.The mathematical model is established for the compound system and the single-effect system,and the simulation conditions are determined.The performance of the compound system is better than that of the single-effect system,and pressure ratio and generating temperature have a great effect on the system performance.With the increase of evaporating temperature,absorption efficiency and solution heat exchanger efficiency,the system performance is improved,while the influence of condensing temperature and absorber outlet temperature on system performance is reversed.Secondly,the two-dimensional numerical simulation of the liquid-gas ejector is carried out.The structure size of the ejector is designed according to the working principle.This paper uses CFD technology to build the physical model,selects multiphase flow and turbulence model,gives boundary conditions and solves,and analyzes the fluid pressure change inside the ejector.Without changing other operating conditions,the ejection performance is improved with the increase of the main flow pressure and the secondary flow pressure,and the decrease of the outlet back pressure.Finally,an experimental bench is built to study the boiling heat transfer characteristics of the working pair in the smooth horizontal tubes.The mass fraction of refrigerant is 11.1%,the test section is stainless steel annular tube.The experimental conditions are determined according to the actual operating conditions of the absorption refrigeration cycle,and the flow boiling heat transfer coefficient is measured.The boiling heat transfer coefficient increases with the increase of heat flux and mass flux.The boiling heat transfer coefficient of large tubes is generally larger than that of small tubes,and the pressure drop obtained by the experiment is less than 0.1k Pa/m.The results of numerical simulation and experiment will be beneficial to optimize the design of ejector and generator,and further promote the development of absorption-ejection refrigeration cycle.