The Effect of Emissivity and Temprature on Heat Transfer Coefficient in a Modified Cavity Receiver of Solar Central Collector

An understanding of convective heat loss is essential to the design of efficient solar central receivers. The numerical study of combined laminar natural convection and surface radiation heat transfer in a modified cavity receiver of solar central collector is presented in this paper. A 2D-dimensional numerical analysis for combined natural convection and surface radiation is developed. The influence of the receiver inclination, the fluid temperature and the emissivities on the convective and radiation heat losses is reported in this investigation.The results show that the convective heat loss from this receiver is significantly influenced by the inclination of the receiver whereas the radiation heat loss is considerably affected by surface properties of the receiver. It was found that the convective loss was significantly influenced by the orientation of the receiver. Hence, the model may effectively be used to estimate the convection and radiation heat losses from the cavity receiver of solar parabolic dish collector system.

Keywords:

Emisivity , Radiation , Solar cavity , Fluent , Numerical study , convection , Surface radiation