In the proposed research work the design of single tube cavity receiver is analyzed and a new design of double tube cavity receiver is proposed to reduce heat losses computationally using CFD software. A heat transfer and flow simulation are proposed for Single & double tube solar thermal cavity receiver at receiver inclination of 0° without the wind & 0.02kg/s mass flow rate of water at Inlet temperature of 90°C & ambient temperature of 30°. The Numerical study of convection losses in single & double tube cavity receiver of solar parabolic dish collector is proposed.Measurements of energy losses, temperature drops, wind speed, working fluid flow rate, and inlet-outlet temperatures of the working fluid are proposed to analyze the performance of Double Tube Cavity Receiver.