Environmental and economic assessment of single-slope solar greenhouse dryer for ginger and turmeric drying in north-eastern region of India

In the present work environmental and economic assessment of a single-slope solar greenhouse dryer (GHD) for drying ginger and turmeric have been attempted under the natural convection (NC) and forced convection (FC) of different air flow rates; FC1 (0.073 m3/s), FC2 (0.089 m3/s), and FC3 (0.107 m3/s). This system was investigated in the climatic conditions of the North East India region to dry the products at zero energy cost by installing this system for greater utility in different drying industries. The moisture reduction was 0.11 (d.b.) or 0.01 (w.b.) and 0.14 (d.b.) or 0.02 (w.b.) from initial values of 10.11 (d.b.) or 0.91 (w.b.) and 6.14 (d.b.) or 0.86 (w.b.) for ginger and turmeric, respectively. The drying time was 6.00 h in GHD under FC3 case and 11.50 h in OSD for ginger and 6.50 h in GHD under FC3 case and 12.50 h in OSD for turmeric. The drying efficiency for ginger and turmeric under the FC3 case was 34.13–37.17% and 30.71–33.28%, respectively. The energy efficiency and energy utilization ratio of the GHD under the FC3 case was 66.66–89.84% and 55.39–72.96%, respectively. The payback periods of 0.81 yr and 0.55 yr were determined for turmeric and ginger, respectively. Furthermore, over the 20 years of the system's life, the system reduced CO2 emissions by 29.48 tonnes compared to 11.10 kg of CO2 emissions produced for the embodied energy used to develop the GHD.