Analysis of Energy - Exergy and indirect solar dryer designed for mint under the influence of various air mass flows

In this paper, an indirect active solar air dryer was designed and constructed. The dryer performance in terms of energy absorption and heat generation was investigated under the impact of air mass flow rate in active and passive modes. Based on the laws of mass and energy conservation, the dryer dimensions were designed and then the dryer was constructed in faculty of agriculture at Shahrekord University. The first and second laws of thermodynamics were applied to analyze the energy and exergy and the influencing components. Experiments on mint were carried out on July 4, 5 and 6, 2015 both in active (fan on) and passive (fan off) modes of the dryer. The experiments were initiated at 9 AM continued to 7 PM, and the effect of air speed at three levels (0.5, 1 and 2 m s-1) was evaluated. Results showed that energy consumption in both the active and passive modes is independent of air flow rate and is more influenced by the moisture content of the mint. The highest exergy efficiency was observed in natural convection mode of the dryer.