Performance analysis of an infrared film assisted solar air heater for drying applications

Solar air heaters are low-cost, simple structure, reliable, and high energy conversion efficiency devices to produce hot air for drying applications. In this study, an infrared film-assisted double pass solar air heater has been developed, manufactured, and tested for a sustainable drying process. The main contribution of this research is the supply of heat energy to continue the drying process even when solar radiation is insufficient. The experiments were carried out in three different weather conditions depending on solar radiation and grape pomace was chosen as the drying product. According to the obtained results, the average thermal efficiency of the solar air heater was determined as 76.4% for the experiment under high solar intensity, 64.1% for the experiment under medium solar intensity, and 45.63% for the experiment under low intensity. The effective moisture diffusivity values and the mass transfer coefficient were calculated in the range of 5.70 x 10(-12) to 2.39 x 10(-10) m(2)/s and 1.52 x 10(-9) to 1.94 x 10(-7) m/s, respectively. In the experiment that was conducted on high solar intensity, where 69% of heat energy was provided from solar energy, the product dried in 110 min. In the experiment carried out on a day when the solar radiation was insufficient, it was observed that the product dried in 220 min and the heat energy from solar energy decreased to 21% and the energy rate consumed by infrared film increased to 61%.