Efficiency Analysis of an Air Solar Flat Plate Collector in Different Convection Modes

Solar energy is an inexpensive source of energy for most of the countries. Use of this source of energy can be spread with the increase of solar systems efficiency. Solar energy collectors are the devices employed to gain useful heat energy from incident solar radiation. In the present investigation, an air solar flat plate collector was developed for research purposes. The collector absorber is developed in the form of a window shade for increasing contact area of air circulation. The experiments were performed in two convection modes and data were collected from 18-24 June 2011 throughout the day, in which atmospheric conditions were almost uniform. Thermal and efficiency analysis is carried out with the experiment data. Experimental results in natural and forced convection modes were evaluated and discussed. It was concluded that the collector efficiency in forced convection was lower, but the low air temperature difference between inlet and outlet decreased its heat loss. It is found that the average air speed in the forced convection was about 21% higher than the natural convection.