Drying kinetics and economic analysis of bitter gourd flakes drying inside hybrid greenhouse dryer

In this study, a heat storage–based hybrid greenhouse dryer has been developed and analysed for drying bitter gourd flakes under the climatic condition of Ranchi, India. Proposed heat storage–based hybrid greenhouse dryer consists of a solar air heater with a 2.12-m² area, greenhouse dryer and DC fan to induce and force the air. The significant objective of the present study is to analyse the drying efficiency, drying kinetics, property analysis, economic analysis, embodied energy and CO₂ mitigation of the hybrid greenhouse dryer for drying of bitter gourd flakes. An experiment was performed simultaneously on proposed system and open sun drying for the proper comparative analysis. Moisture contents reduced from 88.14 to 10.14% in 6 h in proposed dryer and 88.14 to 11.01% in 15 h for open system. Thus, significant drying time is reduced in proposed system by 8 h as compared to open system. Environmental impact analysis shows that the energy payback time was found to be 0.4907 years only. Cost of the proposed system dryer is 22664.30 INR. The total embodied energy is found 1591.07 kWh and earned carbon credit ranges from 16844.76 to 67379.05 INR, while CO₂ mitigation was 46.28 tonnes for 35 years of expected lifetime. Seven standard mathematical models for drying of bitter gourd flakes were studied. Ahmad and Prakash model was found to be the best as compared to other models. The metal contents of dried bitter gourd flakes were also examined. Bitter gourd dried in proposed dryers possesses superior metal content as compared to open systems. Impact analysis demonstrates that the hybrid greenhouse dryer is more suitable for reducing post-harvest loss with environmental sustainability.