A numerical study has been carried out to analyse the thermal performance of the receiver system of solar Linear Fresnel Reflector (LFR) module. Realistic flux conditions obtained by the optical analyses are applied as the boundary condition to the circumference of the absorber. Heat losses caused by convection as well as radiation from the parabolic secondary receiver are investigated under evacuated and non-evacuated annular region between the absorber and the glass tube. The investigation has been carried out to determine the heat loss by varying the annular gap between the absorber tube and the protective glass. © 2017. The Authors.