The Analysis Of Heat Exchange System Of Dish Solar Stirling Engine And The Flow Filed Of Working Substance

Stirling engine is one of the key components in the dish solar thermal powergeneration system. The performance of it have a direct impact on the efficiency ofthermal power generation system. Making sure the information about the heat transfermechanism of the Stirling engine’s heat exchange system and its internal distributionof working medium have a special significance for the engine design and optimization.In this paper, the author regard the heat exchange system of25kW α typeswashplate Stirling engine with four-cylinder and double-acting as study object,researching on its heat transfer mechanism and the flow charactristics of internalworking medium. The research are mainly included the following contents:The investigation of thermodynamic cycle of Stirling engine heat exchangesystem and heat transfer mechanism. First, the analysis on Striling ideal cycle andpractical cycle validate that the efficiency of practical Stirling cycle is lower than theCarnot cycle, because of dead volume and all kinds of loses. Then, in the α typeStirling engine for an instance, the paper introduce the Smith Analytical Method, andbriefly analyse the swashplate and its piston motion. Finally, based on the heattransfer mechanism of each link of heat exchange system, a heat transfer model isproposed.The design and analysis on the heat exchange system of Stirling engine.According to design requirements, the struction and parameters of Stirling engine heatexchange system were analysed, its dead volume was defined, then the work in a fullcircle by a single work unit was calculated. On the basis of swashplate and its pistonmotion analysis and the heat exchange system(Heater, Regenerator and Cooler) designcalculation, a3D model of the heat exchange system of25kW α type swashplateStirling engine with four-cylinder and double-acting and a mathematical model ofheat loss and thermal efficiency in heat exchange system were established, but alsothe study analyzed the impact of the many kinds of heat losses on thermal efficiency.A numerical simulation and analysis of the flow field characteristic of wokingmedium in the heat exchange system of Stirling engine. On the fundation of geometricmodel of the heat exchange system for Stirling engine, it’s simulation model was built.Based on the basic theoretical knowledge of Computational Fluid Dynamics,combined with the performance of flow field in heat exchange system, a mathematical model of fluid flow and heat transfer were established. After setting solutionparameters according to the actual working state of the heat exchange system, theflow characteristic of working medium when the heat exchange system is workingwere numerically simulated. It reveals that the velocity, pressure, temperaturedistribution regulatities of working medium in different time. Then it also draws someconclusions, for example, the velocity field of working medium is complicated withinstantaneous changes, the temperature in regenerator is linear distribution and steady,and it can reduces the expanding energy for snirl if the engine uses arc instead of rightangle for slow transition.