The substantial energy demand for domestic hot water in Iraq, coupled with the intermittent availability of solar energy, presents a significant challenge. Conventional solar water heaters (SWHs) often fail to provide a consistent hot water supply, particularly during post-sunset hours and overcast conditions. To address this limitation, this study investigates the integration of latent heat thermal storage, utilizing phase change materials (PCMs), into SWHs. A comprehensive methodology combining experimental analysis and numerical simulation was employed. An experimental prototype of a PCM-enhanced SWH was constructed and tested under the climatic conditions of Baghdad, and its performance was directly compared against a conventional SWH operating simultaneously. Concurrently, a dynamic heat transfer model was developed and validated in ANSYS Fluent to simulate the PCM's phase transition behavior and optimize system design. The results demonstrate a significant performance improvement, the PCM-SWH extended the availability of hot water (>40°C) for an average of 4.3 hours after sunset, representing a 95% increase in operational duration compared to the conventional system. Furthermore, the daily thermal efficiency saw a relative increase of 23.5%, rising from 28.1% for the conventional SWH to 34.7% for the hybrid system, the study also identified optimal design parameters, including RT55 paraffin as the PCM, a mass of 30 kg, and a finned cylindrical storage unit configuration, this research confirms the technical viability and substantial benefits of integrating PCMs in solar water heaters for the Iraqi context, offering a practical pathway toward reducing dependency on the electrical grid and enhancing energy security.
Aqeel Radhi (Mon,) studied this question.