Research On Heat Transfer Characteristics And Optimization Of Multi-layer Volumetric Solar Energy Receiver

With the gradual depletion of non-renewable energy such as coal and oil.The energy crisis facing mankind is becoming more and more serious.The use of renewable energy is a key means of addressing energy and environmental crises,and solar is an important renewable energy.Using solar energy to generate electricity can save resources without destroying the environment.Tower Solar Power Generation is a promising way to generate electricity from solar energy,in which porous volumetric solar receiver is a key component.On the basis of previous scholars’ research on single-layer and double-layer porous volumetric solar receiver According to the current research works,the porous volumetric solar receiver is made of singlelayer porous medium.However,the volumetric solar receiver made of multi-layer porous media is presented in this work.And the corresponding thermal performance are studied,the fluid flow and heat transfer inside the porous medium are described by the Darcy-Forchheimer equation and the local thermal non-equilibrium model,respectively.The Rosseland approximation is adopted to describe the radiation within the volumetric solar receiver.Analytical solutions for the air temperature,pressure distribution along the receiver and solid phase temperature are derived.The receiver efficiency is also obtained.The influence of pertinent parameters,including the porosity and pore diameter of the porous media are discussed.In addition,the effects of different porous design on the performance of the volumetric solar receiver are investigated.A multi-layer volumetric solar receiver model with different porosity and pore diameter distributions was designed,including increasing or decreasing porosity,increasing or decreasing pore diameter,and a design model in which the porosity or pore diameter first increased and then decreased.The effects of the thickness of the first layer of the receiver on the internal air temperature of the heat receiver and the temperature of the porous skeleton were investigated.At the same time,the temperature of the inlet of the porous skeleton of different models and the thermal efficiency of the receiver were compared.Finally,the distribution of pressure drop inside different models was analyzed.The results show that the parameters of the first layer of the multi-layer volumetric solar receiver have an important impact on the overall performance of the receiver.Comparing the different models,it is found that the multi-layer volumetric solar receiver has the best performance when the porosity first decreases and then increases.The multi-objective optimization is adopted to optimize the three-layer porous volumetric solar receiver system.The optimized objective function is the thermal efficiency and pressure drop of the receiver.These two are important indicators for evaluating the performance of the receiver.The results show that the porosity distribution of the first layer and the third layer are obviously higher than that of the second layer,and the pore diameter distribution of the first layer and the third layer are also higher than that of the second layer.The first layer is the thinnest layer of the receiver,and the third layer is the thickest layer of the receiver.According to this rule,the best three-layer porous volumetric solar receiver can be designed.Finally,the incident radiation is designed to change periodically.Under the condition of unsteady state,the analytical solution of the internal porous skeleton temperature and air temperature of the single-layer solar receiver is obtained,and the effects of the incident radiation on skeleton temperature at the inlet and the air temperature at the outlet are analyzed.The temperature distribution in the single-layer solar receiver at different time was studied.