Combined laminar natural convection and surface radiation heat transfer in a modified cavity receiver of solar parabolic dish

Abstract

The numerical study of combined laminar natural convection and surface radiation heat transfer in a modified cavity receiver of solar parabolic dish collector is presented in this paper. A two-dimensional simulation model for combined natural convection and surface radiation is developed. The influence of operating temperature, emissivity of the surface, orientation and the geometry on the total heat loss from the receiver is investigated. The convective heat loss from the modified receiver is significantly influenced by the inclination of the receiver whereas the radiation heat loss is considerably affected by surface properties of the receiver. The Nusselt number correlations are proposed separately for both natural convection and surface radiation based on large set of numerical data for a given range of parameters of practical interest. It is observed that the convection and radiation heat losses are found respectively 52% and 71.34% of the total heat loss at 0° inclination and 40.72% and 59.28% at 90° inclination for the modified cavity receiver with an area ratio of 8 and 400 °C. The convection and radiation numerical procedure is validated with other models. The results obtained from the present numerical procedure are in reasonable agreement with other well-known open cavity models.