Drying kinetics, energy, statistical, economic, and proximate analysis of a greenhouse dryer using different glazing materials for Coccinia grandis drying

Abstract

In this study, ivy gourd (Coccinia grandis) was subjected to various drying processes, including Open Sun Drying (OSD) and Greenhouse Dryer (GD), using different glazing materials such as Ultraviolet Polyethylene (UVP) and Drip Lock (DL) sheets in both passive and active modes. The dryer’s performance was assessed based on drying kinetics, energy, statistical, economic, and proximate analysis. In active mode, the DL sheet GD (DLGD) significantly reduced the moisture content of ivy gourd from 92.8 % to 10 % within 5 days, outperforming the UVP sheet GD (UVPGD), which required 6 days. In passive mode, the DLGD and UVPGD achieved the same result in 7 and 8 days, respectively, while OSD required 9 days for comparable moisture reduction. The dryer efficiency for UVPGD was 27.07 % in passive mode and 36.09 % in active mode. In contrast, the DLGD exhibited higher efficiencies of 30.93 % in passive mode and 43.31 % in active mode. Eleven mathematical models were considered to characterize the drying process of ivy gourd, with the two-term exponential model being the best fit for UVPGD and DLGD in active mode. The Prakash and Kumar model was found to be optimal for UVPGD and DLGD in passive mode. Economic analysis demonstrated that UVPGD in passive mode had the lowest capital cost and a payback period of 0.2985 years, whereas DLGD in active mode maintained payback periods below 0.5 years, indicating rapid cost recovery. Proximate analysis revealed that DLGD in active mode retained more carbohydrates, with percentages 8.3 %, 3.94 %, 3.29 %, and 2.17 % higher than OSD, UVPGD in passive mode, UVPGD in active mode, and DLGD in passive mode, respectively. Calcium retention was greater in active mode, while Vitamin C retention was higher in passive mode. The study identifies DLGD as the top performer across all modes, making it a recommended choice for commercial drying applications.