The experimental new hybrid solar dryer and hot water storage system of thin layer coffee bean dehumidification

Abstract The thin layer coffee beans dehumidification and hot water storage were investigated in solar greenhouse dryer simultaneously. The thermal energy was stored for use in the absence of sunlight. The conditions were studied the flow rate of water circulating, model of installation for solar collector assistance, the area ratio of product dehumidification to solar hot water producing (Ad:Ac), flow pattern of water circulation and capacity tank of water circulating in the system. The experiments were found the flow pattern of water circulation within the force flow 0.20 kg/s-mˆ2, tray products temperature (45 deg. C) at (Ad:Ac) 1:1, capacity tank of water circulating (60 L). The thermal energy can be used and stored in the form of hot water and reused at a time without sunlight as well. The initial coffee beans moisture content was dropped from 55 to below 12 (%w.b.) in 12 h drying time. The optimum of mathematical equations for thin layer coffee beans drying based on Midilli mathematical model i.e. (MR = a exp(-ktˆn) – bt); k = 0.03838, n = 1.56771, a = 1.03046, b = −0.00477, R 2  = 0.9896, RMSE = 0.0420. Moreover, the effective moisture diffusivity coefficient of 9.754 × 10ˆ-11 mˆ2/s.