Experimental investigation on heat-transfer characteristics of a cylindrical cavity receiver with pressurized air in helical pipe

Abstract

A concentrating solar system is established for the experimental investigation on a cylindrical cavity receiver. With a built-in helical pipe, the receiver is loaded at the focus point of a parabolic dish, driven by a double-axis tracking system. The helical pipe contains pressurized air as the heat transfer fluid (HTF), heated by concentrated solar irradiation. The experimental investigation analyzed operation parameters effects on both heat losses and the thermal efficiencies, which are direct normal irradiance (DNI), the inlet temperature of HTF and the mass flow rate of HTF. This study also proposed an innovative mathematical model for experiment data processing. The results indicated the increase of DNI from 201.7 W/m2 to 504.3 W/m2 led to a decrease of the thermal efficiency, the increase of the inlet temperature from 150 °C to 200 °C emerged a same tendency. The increase of the mass flow rate from 0.05 kg/s to 0.11 kg/s was on the contrary, since it decreased total heat losses. Good agreements were achieved by compared numerical simulation results of previous studies to the experiment results. Subsequently, a method for thermal performance enhancement was summarized through experimental investigation results, which could be a mentionable improvement for cavity receiver research.