Study of the enhancement in the performance of a hybrid flat plate solar collector using water and air as working fluids

A hybrid flat solar collector was manufactured from basic materials to combine the effects of both water and air solar heaters. The reason is to increase the amount of heat delivered to water by doubling the heat sources, one from the direct beam of sun and the other from the hot air delivered by the air solar heater. In addition, the flow of water inside the solar heater is made in a thin layer so that much heat can be gained by water per unit time. The outlet hot air of the solar air heater enters air ducts that pass through the solar water heater. With a constant water flowrate of 0.0167 kg/s, three different air velocities (1.7, 2.1, and 2.4 m/s) were applied to determine the optimum air velocity that results in the maximum outlet water temperature and the maximum removal factor FR for the solar water heater. The experiment was run from 10:00 a.m. to 2:00 p.m. every day during June 2023 and the data was recorded every 15 min. The data obtained from the experiment showed that the lowest air speed (1.7 m/s) results in the highest outlet water temperature (63°C) and heat removal factor FR (0.74).