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

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 degrees E and latitude 34.27 degrees N). The test findings revealed that the ultimate stored water temperature of SWH with PM existence rose by 12.1 degrees C (case 2) when compared to that without PM (case 1). Furthermore, the PCM improved the water thermal storage by 8.51 degrees 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 (eta ( 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.