Experimental study on solar wall by considering parametric sensitivity analysis to enhance heat transfer and energy grade using compound parabolic concentrator and pulsating heat pipe

Enhancing high-grade and rapid thermal storage for solar energy utilization is of paramount importance in reducing building energy consumption. Therefore, this study combines the Compound Parabolic Concentrator (CPC) and Pulsating Heat Pipe (PHP) to propose an integrated CPC-PHP solar wall (CPC-PHP-SW) that can enhance solar energy grade and rapid thermal storage. The mixed working fluid for CPC-PHP-SW is developed to reduce the dependence on solar radiation intensity and facilitate PHP startup. Furthermore, the operating characteristics and heat transfer performances of the CPC-PHP-SW are studied experimentally under various factors, including solar radiation intensity, working fluid, and cooling temperature. Sensitivity analyses of these three factors on heat transfer performances are conducted using Multi-factor analysis of variance. Results highlight that solar radiation intensity is the most influential factor on heat transfer performance, followed by cooling temperature, and working fluid. Moreover, employing a CPC with a concentration ratio of 2 reduces thermal resistance by up to 56.46 %, while the maximum effective thermal conductivity increases by up to 129.65 %. A recommended methanol to water ratio is 1:3, which effectively copes with a wide range of solar radiation intensity. These findings provide valuable references for the design and application of CPC-PHP-SW in building envelopes.