Experimental Heat Transport Investigation of a Novel Solar Parabolic Trough Collector With a Rotating Receiver Tube in Winter Conditions

Abstract In a quest to improve the efficiency of the existing parabolic solar water heater, many novel approaches have been adopted. In the present study, a solar parabolic trough collector augmented with a rotating receiver tube is analyzed experimentally. For this, a conventional parabolic trough collector is modified to introduce rotation to the receiver tube via a rotary union and high-torque gear motor (12 V direct current (DC)). Manual tracking is adopted with the help of a solar tracking pin to ensure uniform and normal solar irradiation over the aperture of the parabolic trough collector. A robust data acquisition system is used to capture experimental data via an eight-channel digital data logger with the help of PT-100 thermocouples. The results suggest that, with the rotation of the receiver tube, there is an enhancement in the outlet temperature from the solar collector when the mass flowrate is high (>0.3 lpm), while there is a deterioration in the corresponding outlet temperature with a lower mass flowrate. An enhancement in the outlet temperature of around 65.56% and thermal efficiency of around 21% is observed when the rotational speed increases from 0 rpm to 5 rpm. Moreover, in the rotary motion of the receiver tube, the maximum temperature difference (ΔTmax) is observed at the minimum mass flowrate of 0.1 lpm, resulting in values of 14.72 °C, 17.76 °C, and 20.05 °C for rotational speeds of 1 rpm, 3 rpm, and 5 rpm, respectively. The results suggest that this novel rotating parabolic trough collector can enhance the performance of existing parabolic trough collectors and contribute to harvesting solar energy more efficiently.