Abstract:
This study investigates the thermal performance of solar water heaters based on different insulation material by using Comsol Multiphysics software. The main aim was to evaluate how different operational parameters specifically water flow rate and insulation materials affect the efficiency of solar collectors and storage tanks. The analysis was conducted under exterior temperatures of 17 °C, 25 °C, and 30 °C, representing cold, medium, and warm climates, respectively. Previous research highlights the critical role of system parameters and material selection in improving thermal efficiency and reducing energy loss. Building on this, the study underscores the importance of optimizing insulation and flow rates to enhance solar water heater performance, particularly in Rwanda, where climate conditions and economic considerations significantly influence energy system adoption. The simulation of the solar collector and tank was carried out using COMSOL Multiphysics. Different operating conditions were tested, focusing on three main insulation materials wood, glass wool, and fiberglass and varying water flow rates. The system’s thermal performance was evaluated by analyzing heat retention and losses under three climate conditions (17 °C, 25 °C, and 30 °C). The objective was to determine the optimal flow rate for domestic applications and identify the insulation material that delivers the best thermal performance across different environmental conditions.
This study found that a water flow rate of 0.02 kg/s optimally balanced temperature rise and water availability for domestic use. Fiberglass insulation demonstrated superior thermal performance, followed by glass wool, while wood insulation proved inadequate due to excessive heat loss. Fiberglass and glass wool tanks maintained stable temperatures across various climates, whereas wood tanks struggled in colder conditions. The findings highlight the critical importance of insulation material selection and system optimization for thermal efficiency. For Rwanda, recommendations include promoting high-performance insulation, subsidizing solar water heating systems, and establishing design and installation standards. Further research is needed on economic feasibility, long-term durability, and renewable energy integration.
