Energy and enviro-economic analysis of tomato slices solar drying: An experimental approach

Three laboratory-scale drying systems, which are direct solar dryer (SD), solar dryer-assisted solar water collector (SCD), and solar dryer provided with a heat pump (HPD) to generate hot water to the heat exchanger, are considered in this work for drying tomato surplus. The study reported the kinetics, energy, environmental, and economic analysis as crucial investment factors. Outcomes showed that SD, SCD, and HPD took, respectively, 16 h within two drying days, 14 and 13 h, to reduce the moisture content from 14.68 +/- 0.02 to 0.13 (g/g), with a significant diffusional stage for both SCD and HPD. Using a heat pump increased the specific energy consumption (SEC) of HPD ranging from 0.87 to 2.79 kJ/kg. The annual saving attained 9.5 x 104, 1.2 x 105, and 1.57 x 105 DZD with feasible payback periods at 3.67, 4.95, and 2.98 years for SD, SCD, and HPD, respectively. The systems had a CO2/emission of 36.60, 100.5, and 43.68 kg/year and net CO2/mitigation at 9.21, 25.18, and 10.99 tons/year, respectively, for SD, SCD, and HPD. Among the examined drying systems, HPD outperformed the best in energy and enviro-economic and can be considered to invest at a large scale by the industrials or farmers.