Optimizing flat plate solar collector geometry for a solar water heating system

This paper presents results obtained when comparing the performance of a solar water heating system equipped with flat plate solar collector panels of numerically identical surface area but of different geometric configuration. Data was obtained inside a laboratory using a solar simulator consisting of an array of halogen lamps. The amount of heat acquired from collectors of solar energy depends primarily on the surface area that is exposed to the solar irradiance. However, the geometry of the collectors (such as vertically long, horizontally long, square or equal sides) was thought of affecting the amount of heat harvested. The experimental work tested specially manufactured flat plate solar collectors (provided by a local manufacturer). All three panels had identical collector's surface area but different geometrical orientation and were individually attached to a typical solar water heating system. The circulation of the water from the panel to the geyser was due to the self-induced thermo-syphon effect. The average solar radiation intensity was measurement on the collector's surface and, six thermocouples were inserted inside the tank at different levels to measure the water temperature on an hourly basis during the test period (7 hours per day for two consecutive days). The results obtained indicated that the system's thermal efficiency was best when the square collector was used. A dimensional analysis using the Π Buckingham method that was performed on the parameters affecting a flat plate solar collector yielded three dimensionless numbers that can lead to a power law relationship enhancing solar water heating systems' design.