Thermal Performance Characteristics of Porous Media Receiver Exposed to Concentrated Solar Radiation

Solar thermal power plants with central receiver systems are promising candidates for the harvest of solar energy. However, the development and application of volumetric receivers are restricted owing to the nonuniformity of incident heat flux distribution, which may reduce thermal efficiency and even lead to structural damage. In the present work, the influence of thermal conductivity and radiation distribution on the thermal response of porous receivers is studied. On this basis, a transient thermal model was developed. It was found that porous media receivers with larger thickness will ensure that the thermal energy of the receivers will be fully taken advantage of by flowing air and improve the efficiency of the whole system. For porous receivers exposed to concentrated solar radiation with a Gaussian distribution, the temperature distribution along the radial direction also distributes in a Gaussian shape, with a mean temperature the same as that of uniform distribution heat flux. In working conditions where the intensity of concentrated solar radiation changes rapidly, the rate of temperature increase/decrease may be too high, which may cause damage to receivers.