Theoretical Optimization of The Storage Tank of A Solar Water Heater using Locally Available Materials

Hot water production using solar water heaters is one of the most promising applications of solar energy for countries such as Burkina Faso. This study examines the performance of a local solar domestic hot water production system by optimizing the efficiency of the storage tank. The tank is designed using locally available materials such as steel and glass wool. In this study, we determined the temporal evolution of the temperature of the stored water as a function of the thickness of the insulation; the evolution of water temperatures at different levels of the tank during the day and at night; the stored power and the temperatures of the water layers during withdrawal. To calculate the temperature of the water in the storage tank, the stirred model was adopted. This model assumes that the temperature in the tank is uniform. The regime is considered transient, and the total heat loss in the tank is equal to the sum of the radial flows plus the flow through the curved bottoms. The power recovered by the heat transfer fluid is defined as the difference between the incident solar energy and the heat losses. The results show that the theoretical temperature of the stored water varies between 50°C and 65°C for insulation thicknesses ranging from 10 mm to 80 mm; a maximum experimental stored power of approximately 1400 W. The theoretical maximum average daily temperature of the stored water is 70°C and the experimental value is 53°C. These results show that the efficiency of the tank depends both on the daily power stored and the quality of the insulation.