Study On Design And Heat Transfer Characteristics Of A Solar Conical Cavity Receiver

Concentrated Solar Power(CSP)technology is a clean and efficient way which can convert solar energy into electrical energy.The development of CSP will help reduce the dependence on fossil energy and accelerate the transformation of the current energy structure.The receiver plays a key role of converting solar energy into heat energy,and its research and optimization can effectively improve the total efficiency of the CSP.In this paper,the simulation research of conical cavity solar receiver was carried out from two aspects of optics and heat.The influence of geometric parameters and tube arrangement on the receiver was explored.According to the existing parabolic dish of our research group,a conical cavity solar receiver was designed in this paper.Based on the Monte Carlo ray tracing method,the software Trace Pro was used to investigate the influence of the focus position of the parabolic reflector and some important geometric parameters on the optical performance of the receiver.The results show that the optical efficiency of the receiver increases with the increase of the number of loops,and decreases with the increase of the conical angle and the insulation thickness;when all the reflected lights from the parabolic reflector can enter the cavity,the influence of various factors on the optical efficiency is not obvious,and the maximum difference is only 1.15%.According to the characteristics of the heat flux distribution in the cavity,the tube surface was simplified into a plurality of areas with uniform heat flux density,which is convenient to be applied to the wall boundary conditions in the heat transfer process.Subsequently,ANSYS was used to investigate the effect of geometric parameters on the heat loss and total efficiency of the receiver.The simulation results show that: the radiation heat loss of the receiver is always the largest,followed by the convection heat loss,and the conduction heat loss is always the smallest;with the increase of the conical angle and the number of loops and the insulation thickness,the total efficiency of the receiver is increased first and then decreased;the cavity receiver with conical angle of 5 °,number of loops of 13 and insulation thickness of 175 mm has the highest total efficiency which can reach 70.52%.The total efficiency of the conical cavity receiver was analyzed under different flowdirections of the working fluid and different tube arrangement.The result shows that with the increase of the distance from the aperture to the focal point of the parabolic reflector,the total efficiency of the receiver shows an opposite change rule due to the different flow direction of the working fluid.The conical cavity receiver with single spiral tube arrangement and working fluid flowing upward has the highest total efficiency,up to71.35%.The simplified method that combines the optical and thermal processes of the receiver can be applied to the research of receivers with similar structures.The results of this paper also provide guidance for achieving a higher total efficiency of a conical cavity receiver.