Improving the performance of the thermal energy storage of the solar water heater by using porous medium and phase change material

Abstract

ABSTRACT In this work, an experimental assessment of a designed solar water heater (SWH) was carried out under the Iraqi weather conditions. In the SWH practical model, a porous medium (pebbles) is used as an absorber surface in the solar collector, and a raw paraffinic wax is utilized as a Phase Change Material (PCM) in the thermal storage tank. Three experimental cases have been conducted for analyzing the SWH thermal performance: (1) Without using Porous Medium (PM) and PCM, (2) with PM and without PCM, and (3) with using PM and PCM. The experimental tests were performed at Tikrit, Iraq (longitude 43.35°E and latitude 34.27°N). The test findings revealed that the ultimate stored water temperature of SWH with PM existence rose by 12.1°C (case 2) when compared to that without PM (case 1). Furthermore, the PCM improved the water thermal storage by 8.51°C for case 3 after the test period of (17:00 to 22:30 h) as compared to the case 2 without the PCM. The results for the total thermal efficiency (η o ) of the system with storage unit manifested an improvement of around 2.83% and 6.35% in case 3 compared to cases 2 and 1, respectively. In comparison to previous studies, the present study found that the higher thermal performance of the SWH than those determined by preceding studies.