Heat loss characteristics of trapezoidal cavity receiver for solar linear concentrating system

In this paper, a numerical study of combined natural convection and surface radiation heat transfer in a solar trapezoidal cavity absorber for Compact Linear Fresnel Reflector (CLFR) is presented. The CFD pack- age, FLUENT 6.3 is used to develop the 2-D, non-Boussinesq, steady state, laminar, combined natural con- vection and surface radiation heat transfer model for a trapezoidal cavity absorber. The validation of the present non-Boussinesq numerical procedure is compared with other closed cavity model. Based on the validated non-Boussinesq model, the combined heat loss coefficients are predicted for various parame- ters such as Grashof number, absorber angles, surface emissivity, aspect ratio, temperature ratio and radi- ation–conduction number. The numerical simulation results are presented in terms of Nusselt number correlation to show the effect of these parameters on combined natural convection and surface radiation heat loss.