Simulation And Experimental Verification On Optics-thermal Process Of Solar Cavity Tubular Receiver

The high temperature air heat absorber is a key component of the solar gas turbine power generation system.It can convert solar energy into heat and transfer it to the working fluid.The cavity tube air receiver has the advantages of simple structure and strong pressure-bearing capacity,which is very suitable for solar gas turbine systems.Under concentrating conditions,the flux is high,the flux distribution is uneven and changes all the time,and there is the possibility of local over-temperature on the surface of the receiver.Therefore,the design and operation optimization are very important.In this paper,the simulation and experiment verification of tower-type concentrating and high-temperature heat absorption is carried out for the cavity tube receiver,and it is planned to develop a calculation method of photo-thermal coupling from the mirror field to the receiver,and then it is expected to provide a useful reference for the receiver design and operation.Based on the Monte Carlo ray tracing method,a tower concentrator model was established,and a Lambertian plate and CCD camera were used to carry out tower concentrating experiments on heliostats at different positions.The simulation results and the measurement results are in good agreement with the spot shape,size and flux distribution.The maximum relative error of peak flux is 5.29%.The tower concentrator model can obtain the characteristics and laws of the flux distribution in the cavity,and provide boundary conditions for the light-thermal coupling calculation.Based on the lumped parameter method and the heat balance method,the light-heat coupling model is established.The tube is divided into three parts: the front surface,the fluid domain and the back surface.Considering the circumferential and axial heat conduction of the tube wall,calculate the temperature distribution in the cavity of the receiver.Carry out heat absorption test under real light at Qingshanhu energy research base,the air outlet temperature is 537 ℃,and the highest wall temperature is 742 ℃.Continue to increase the number of heliostats,the maximum wall temperature can exceed 1000 ℃,and the outlet temperature of the receiver can exceed 800 ℃.Comparing the measured results of the tube wall temperature with the simulation results,the maximum relative error in steady state is6.78%.A light-heat coupling simulation study was carried out on the cavity tube receiver.At noon on the vernal equinox and under the conditions of 70 heliostats,the outlet air temperature of the receiver was 740.3 ℃,and the maximum wall temperature reached 962.6 ℃.The overall receiver presents the characteristics of uneven temperature distribution and high wall temperature.In order to optimize the temperature distribution in the cavity,the coating optimization and aiming optimization strategies based on genetic algorithm are proposed.The simulation results show that the maximum wall temperature is reduced by 72.7 ℃ after coating optimization;after the aiming optimization,the peak flux is reduced by 26.6%,and the maximum wall temperature is reduced by 45.2 ℃.The research work in this paper is expected to provide reference and reference for the design,verification and safe and stable operation of the cavity receiver.