An Experimentally study of the effect of hot water flow rate on solar collector systems

Solar power is an appealing green energy source. Domestic hot water represents the second-largest consumption of household electricity. The most straightforward application of solar energy is converting it into useful heat, particularly for water heating systems. The flat plate collector is the most common device for this conversion. This paper details the design and experimental analysis of the flow rate within the collector of a natural circulation solar water heater, which was constructed and tested in Erbil, Iraq, at a latitude of 36 degrees. The collector is placed towards the south with a tilt angle of 45o with the horizontal. The results indicate that the system's performance is highly dependent on the collector's flow rate and the incident solar radiation. The maximum flow rate within the system due to natural circulation is approximately 0.207 litres per minute per square meter. During the cold season, the highest water temperature from the header pipes ranges between 50 to 56°C; in the hot season, it reaches about 80 to 90°C. Energy savings for February, March, and April are 326.6 MJ, 277.2 MJ, and 252 MJ, respectively.