Effect of ventilated solar-geothermal drying on 3E (exergy, energy, and economic analysis), and quality attributes of tomato paste

In order to explore the feasibility of suitable drying technology of tomato-paste, four solar drying methods were employed, namely (i) Basic Solar-drying Mode (SDM), (ii) Solar-Geothermal Drying (SGD), (iii) Convective Ventilated Solar Drying (CVD), and (iv) Combination of Ventilation and Geothermal Drying (VHD) and their effect on exergy efficiency, economic and quality attributes were investigated. Results showed that the drying time using different drying methods was 10, 9, 8, and 4.5 h for SDM, SGD, CVD, and VHD, respectively. Proposed model could better describe tomato paste drying behavior among eight tested mathematical models. Highest drying efficiency and specific energy consumption were observed for VHD method as 68.27% and 3.21 kWh/kg, respectively. Highest exergy efficiency was recorded for SGD and VHD as 54%. Payback period values were 0.28, 0.325, 0.3, and 0.169 years for SDM, SGD, CVD, and VHD, respectively. Color analysis revealed that CVD method was more suitable with the lowest total color change of 22.41 and highest brightness of the red color of 1.34. SGD method preserved 73.85% and 59.42% of phenol and flavonoid compounds, respectively, while VHD method preserve the highest flavonoid compounds as 82.24% compared to fresh sample. Geothermal energy combined with ventilation is recommended as a suitable drying method for tomato paste in terms of drying time, energy, exergy efficiency, economic, and quality attribute.(c) 2021 Elsevier Ltd. All rights reserved.