Effect of Insertion of the Dish on the Behaviour of the Convective Heat Loss

Abstract

The main contributing factor in analysing the performance of solar parabolic dish system (PDS) is the high amount of heat associated with the higher concentration ratio. To determine the convective heat loss from receiver in real scenario is a challenging task. Installation of these PDS in open environment also causes an escalation in the convection heat loss due to diverse wind circumstances. This work is aimed at providing quantitative insight into examine the heat loss behaviour by the insertion of the dish structure. The study is numerically performed using different wind velocities and attacking angles with constant cavity wall temperature. Free convection study was performed for ranges 0°–90° tilt angle and found s strong dependence of heat loss on the orientation of the dish. While in forced convection cases, different wind incidence angles in addition to tilt angles were examined from 1 to 20 m/s. The detailed convective heat loss patterns provided a clear picture of the effect of the dish. The convective heat loss was drastically changed due to the coupled dish–receiver flow interaction in almost all cases. As a result, the convective heat losses can be described as the function of the orientation of the dish–receiver system. However, the maximum heat loss occurs at zero degree tilt angle during forced convection irrespective of wind incidence angle Also, a critical velocity, depending upon the operating conditions of parabolic dish system, was observed to shift the flow from the mixed convection to forced convection flow.