Two-Phase Closed-Loop Thermosyphon Solar Water Heater with Porous Wick Structure: Performance and Start-Up Time

Abstract

Two-phase closed-loop thermosyphons (TPCLTs) are highly efficient heat transfer devices capable of transporting thermal energy over long distances without the need for other mechanical forces, such as pumPWS. This makes TPCLTs particularly suitable for applications involving solar water heaters. Our objective in this work was to increase the performance of TPCLT solar water heaters by using an evaporator with a porous wick structure (PWS) to achieve a low heat transfer coefficient. Experiments were conducted under three conditions: (1) 40% fill ratio using an evaporator without a PWS, (2) 60% fill ratio using an evaporator without a PWS, (3) 60% fill ratio using an evaporator with a PWS. Our results demonstrate that employing a PWS within the evaporator can enhance efficiency by 12.7% and decrease start-up time by 26.5% under low heating power.