Study On Photo Thermal Properties Of Dish Solar Receiver

With the rapid development of today's social economy,energy demand increases significantly.Therefore,it is of great significance to develop and use a new renewable clean energy.With the widely use of solar energy,the solar thermal technology will become the trend of the development of solar energy technology in the future.Disc solar energy with high power generation efficiency by thermal energy,which has great potential for development.The heat receiver is the core component of the solar collector system,and its performance has an important effect on the efficiency of the disc solar collector system.So,it is important to study the solar thermal performance of the heat receiver.In this paper,the self-made cylindrical and hemispherical heat receiver are studied,based on the existing dish solar test bed.The influence of different factors on the thermal power and thermal efficiency of the heat receiver was analyzed by Tracepro optical software and test.The main conclusions are as follows:After the reflector is installed,the optical efficiency of the heat receiver is improved significantly.Compared with hemispherical reflectors,the conical reflectors is better.When the conical reflector radius of cylindrical heat receiver is 80 mm and the cone angle is 130 degrees,the light distribution in the cavity is uniform and the optical performance is optimal.While the conical reflector radius of hemispherical heat receiver is 40 mm and the cone angle is 120 degrees,the light distribution in the cavity is uniform and the optical performance is optimal.And the optical efficiency of cylindrical receiver is higher than that of hemisphere.The simulation results show that the system performance is the best when the installation distance of the receiver change between 540mm~570mm.When the installation distance is 565 mm,the optical performance is the best,and the optical efficiency of cylindrical and hemispherical receiver and are 88.01% and 85.89% respectively.When the installation distance varies between 525 mm ~535mm and 575 mm ~585mm,the optical performance is poor,and the luminous flux absorbed by the inner tube of the heat receiver,the average energy density,the number of light rays and the optical efficiency of the receiver are rapidly reduced.The experimental results show that the temperature of the receiver is higher when the theoretical focal length is about 555 mm,and the focal spot shape is similar to the theoretical shape.When the installation distance is 565 mm,the temperature is the highest,the focal spot is the smallest,and the energy is the most concentrated.which is consistent with the simulation results.So,it is the best installationposition of the heat receiver.Flow rate and direct irradiance are the main factors that affect the thermal power and thermal efficiency of disc solar heat receiver,and the thermal power and thermal efficiency are positively correlated with flow rate.The optimum flow rate for the test was27.78 g/s.The thermal power is positively correlated with direct irradiance,while the thermal efficiency is negatively correlated with direct irradiance.And filled with heat absorbing paint in the heat absorbing copper tube is an effective method to improve the thermal performance of dish solar heat receiver.The thermal power and thermal efficiency of the system have been significantly improved after brushing the heat paint.And the heat receiver has better thermal performance when the thermal efficiency of cylindrical cavity-receiver is higher 4% than the hemispherical average.Through simulation and experiment,the thermal efficiency of cylindrical cavity receiver is higher than that of the hemispherical cavity receiver with the same ambient temperature,irradiance,flow rate,and inner copper heat receiver area.And the experimental results are in good agreement with the numerical simulation results.