Parabolic Air Collectors with an Evacuated Tube Containing Copper Tube and Spiral Strip, and a New Cavity Receiver: Experimental Performance Analysis

Abstract

Sunray thermal energy is one of the most promising and quickly growing techniques globally. In parabolic trough air collectors (PTAC), receiver design and safety are of paramount importance because of their impact on the overall effectiveness of power plants. However, experimental studies of alternative receivers to improve heat transfer are still to be performed. In this study, a PTAC system was tested experimentally with an evacuated tube: open on one end, containing a copper tube and a spiral strip (case 1), and with a new cavity receiver consisting of several arranged tetragonal pyramidal elements (case 2). Afterward, the results were compared and showed a slightly superior exit air temperature and thermal efficiency performance for case 1. The overall results demonstrate a remarkable convergence of case 2 from case 1 in terms of temperature increase across PTAC, in which the maximum exit air temperature for case 1 is 58.2 °C, a 3.4% increase over case 2 at 0.0105 kg/s mass flow rate. Lastly, the results validate the potential and clarify the specific conclusions of these methods’ application in improving heat exchange in a PTAC.