Parameters Design And Thermostersis Simulation For Stirling Engine Heat Cavity Receiver Of 38kW Dish Solar Power

Photothermal conversion efficiency is an important index of the solar dish Stirling solar thermal power generation system while the heat loss of Stirling engine is key to the photothermal conversion efficiency.Cavity receiver is an important part of the Stirling engine,which plays a leading role in the light and heat transfer.But there are many kinds of heat loss and the heat loss mechanism is complicated,which is the emphasis and difficulty in the design of heat receiver.The mechanism of heat loss of 38 k W dish solar Stirling engine was analyzed In this paper, and the structure and parameters of the absorber are designed,and the numerical calculation of heat loss is carried out.Specific content includes:First of all, the dish solar Stirling engine working principle and the characteristics of cavity absorber,heat pipe, reflecting cone and heat preservation layer are analyzed.A cavity type heat absorber with better heat preservation effect is selected.38 k W dish solar energy Stirling engine cavity type heat absorber opening diameter A1, a heat absorption pipe length L2, absorbing chamber of average diameter D3 parameters are designed and calculated,and the design parameters are verified,which obtained A1=400mm,L2=190mm,D3=650mm.The convective heat loss, the Sterling engine cavity receiver radiation heat loss and heat loss are analyzed.The physical model and the mathematical model of heat loss of the cavity type absorber are established.The heat loss characteristics of the absorber are simulated based on the variable physical parameters of the air,which based on the Fluent software platform.The influence of cavity inclination and heat flux density on heat loss in natural convection is analyzed, and the influence of wind speed, wind direction, angle of cavity and heat flux on the heat loss is analyzed.Research results show that:In the case of natural convection,with the dip angle of cavity absorber is increased, the radiation heat loss Nuc increases, and the radiation heat loss Nur changes little.With the increase of the heat flux, the Nuc and the radiation heat loss of the convective heat loss Nur increase.The heat loss is affected by the combined effects of heat flux, cavity inclination, wind speed and wind direction, and the variation law is more complicated under the forced convection.When the inclination of the cavity heat receiver is 90 degrees, the heat loss Nuc and the radiation heat loss Nur are mainly affected by the wind speed.With the increase of wind speed, convection Nusselt number Nuc increases,the greater the wind speed increases, the amplitude is small, while the radiative Nusselt number Nur decreases.The summer solstice radiation value and height angle than in the winter solstice high at the same time in a high angle cycle,and the height angle and the radiation value of each time are all changed.In the actual dish solar energy Stirling engine operation, the normal power generation under the receiver is low in order to ensure the high heat flux angle, can effectively reduce the heat loss.The research of this paper enriches the research of heat loss of the heat receiver, and provides a theoretical basis for the design of the absorber.