Estimation of convective and radiative heat losses from an inverted trapezoidal cavity receiver of solar linear Fresnel reflector system

•Design of cavity receiver for linear Fresnel reflector system.•Convective and radiative heat loss analyses for linear Fresnel reflector system.•Heat loss analysis of cavity receiver using non-Boussinesq approximation.•Heat loss analyses for different cavity receiver width, temperature and velocity.

Solar linear Fresnel reflector (LFR) system is simple in design and cost effective technology for medium temperature (400 °C) applications. In this article, convective and radiative heat losses from the inverted trapezoidal cavity receiver for solar linear Fresnel reflector are estimated using a two dimensional (2-D) numerical model. The 2-D numerical simulation of trapezoidal cavity receiver is carried out by considering the receiver surface as isothermal conditions. The heat loss analysis is carried out for various receiver geometric and operating parameters viz. thickness of the insulation (tins), aspect ratio (As), cavity depth (Dc), cavity width (w), operating temperature (Tr), cavity cover emissivities (εcc), and wind speed (Vw). Based on the numerical simulation of the receiver, an optimum configuration of trapezoidal cavity receiver is obtained with tins = 300 mm, Dc = 300 mm and As = 2. The total heat losses varies from 663.47 W/m to 1046.3 W/m for w of 300 mm–800 mm at Tr = 500 °C, εcc = 0.5, Vw = 2.5 m/s. The effect of cavity cover emissivity on total heat losses is found to be less significant when compared to that of other cavity parameters. The optimum receiver configuration of the inverted trapezoidal cavity receiver can be used in solar LFR system with minimum heat losses.