Thermohydraulic performance optimization of a novel double-pass solar air heater with vertical PCM-integrated cylinders: A comparative study
Sahibzada Imad Ud Din, Adnan Ibrahim, Sharul Sham Dol, Ahmad Fazlizan, Muhammad Aqil Afham Rahmat, Hariam Luqman Azeez, Banw Omer Ahmed, Ebraheim Salem Alkaabi, Muhammad Ashhad Shahid
Abstract
Solar air heater (SAH) systems are efficient devices to capture solar energy, but their consistent thermohydraulic performance is limited by poor convective heat transfer and fluctuating solar energy. Therefore, this study conducted a three-dimensional numerical investigation to evaluate the thermohydraulic performance of different double-pass solar air heater (DPSAH) configurations featuring vertical PCM cylinders in the second channel. The study examines the flow behaviour, temperature distribution , heat transfer, and thermohydraulic performance parameter ( THPP ) of three distinct PCM cylinder configurations : Case I (PCM on the back plate), Case II (PCM attached to the absorber), and Case III (PCM between the absorber and back plate), across Reynolds numbers ( Re ) from 4741 to 23,258. Results indicate that Case III exhibits the highest heat transfer with the highest Nusselt number ( Nu r ) of 261.59, heat transfer enhancement ratio ( Nu r /Nu s ) of 4.15, friction factor ( f r ) of 0.09 and friction enhancement ratio ( f r / f s ) of 14.75. Case III achieves the highest THPP of 1.705, with thermal efficiency reaching 92.67 % compared to 79.48 % for Case II and 72.89 % for Case I. The highest outlet temperatures recorded were 330.05 K, 322.15 K, and 319.65 K for Cases III, II, and I, respectively, at Re of 4741.