Thermal analysis of a tubular receiver of a fixed spherical solar collector

Abstract

The shape of a solar collector has a significant effect on solar-thermal conversion. The tubular receiver is used as the solar water heater. The incident angles and the difference between the inlet temperature of the receiver and the temperature surrounding it have a direct impact on the efficiency. This research aims to calculate the thermal efficiency of a tubular receiver of a fixed spherical solar collector at different incident angles. The Hottel-Whilier-Bliss equation is used as a basis of calculation. Water is used as the heat transfer fluid with a mass flow of 0.05 kg/s by a pipe. The system is simulated to Figure out the partition of temperature and the distribution of water flow inside the pipe. A brief comparison between a fixed and a tracking system of the tubular and coiled absorber is analyzed. The results show that the thermal efficiency of the tubular absorber increases as the difference between the inlet temperature of the receiver and the surrounding temperature decreases; in addition, the incident angle 6, which is the angle between the sun rays and the axis of revolution of the tubular receiver, decreases. The maximum efficiency reaches 71.85% at the zenith position, and 80.79% at a temperature difference between the receiver and the temperature surrounding per the irradiation equals zero. The fluid can attain a temperature above 1000°C which can generate superheated steam at high pressure.