Study On The Optimal Design Of The Vapour Ejector With Field Synergy Principle

As the key component of the vapour ejector heat pump and cooling system, the vapour ejector plays an important role. However, currently the most vapour ejectors are designed semi-theoretically and semi-empirically for the complex flow in the vapour ejector.The earliest field synergy principle which provides a theoretical guidance for enhancing convective heat transfer was proposed by Professor Guo. Based on the analogy between momentum transport in fluid flow and heat transport in convective heat transfer, Chen et al. made a derivation of the N-S equation of the incompressible fluid. And the drag reduction model and equation of the incompressible fluid flow field synergy were brought out.The drag reduction model and equation of the compressible fluid flow field synergy is proposed and applied to optimize the vapour ejector. The main work and results of this paper are given as follows:(1) The derivation of the N-S equation of the compressible fluid is carried out. The drag reduction model and equation of the compressible fluid flow field synergy are both proposed.(2) Combined with the relationship between the pressure and speed during the isentropic flow process for compressible fluid, the feasibility of the method to optimize the vapour ejector with the compressible fluid flow field synergy is analysed. The results show that the flow in the vapour ejector can be analyzed and explained accurately with the drag reduction model of the compressible fluid flow field synergy. The intersection angle between dimensionless velocity and velocity gradient vectors is termed field synergy angle for compressible fluid flow. The cosine value of the field synergy angle is chosen as the evaluation criteria. The basic analytical method that optimizing the vapour ejector with the compressible fluid flow field synergy is presented.(3) The basic analytical method that optimizing the vapour ejector with the compressible fluid flow field synergy is verified with CFD simulation using different vapour ejector models under heat pump and cooling system conditions. R141b is selected as the working fluid and the pressure bondary conditions are chosen. The cosine value of the field synergy angles are exported locally by user defined function (UDF). The results show that it is a better way to optimize the vapour ejector with the compressible fluid flow field synergy.