Energy and exergy analyses of solar drying process of pistachio

This paper is concerned with the energy and exergy analyses of the drying process of shelled and unshelled pistachios using a solar drying cabinet. Using the first law of thermodynamics, energy analysis was carried to estimate the amounts of energy gained from solar air collectors and the ratios of energy utilization. However, exergy analysis was accomplished to determine the location, type, and magnitude of exergy losses during the solar drying process by applying the second law of thermodynamics. It was deduced that the exergy losses took place mostly in the 15th shelf where the available energy was less utilized. Moreover, the shelled and unshelled pistachios are sufficiently dried in the ranges between 40 and 60 °C and 37 and 62% of relative humidity at 1.23 m s−1 of drying air velocity in 6 h despite the exergy losses of 0.15–3.08 kJ kg−1.