Exergetic optimisation of a solar-biomass hybrid greenhouse dryer in drying banana slices

Abstract

In this study, an elitist non-dominated sorting genetic algorithm was applied in exergetic optimisation of a solar-biomass hybrid greenhouse dryer in drying banana slices. To develop comprehensive relationships for objective functions under each drying mode (solar, biomass, and solar-biomass), the system was linearised around drying and exit air temperatures. The objective functions involved maximising exergy efficiency and drying air temperature of the system. The trade-offs showed that solar and solar-biomass modes required the same airflow rate (0.05 kg/s) indicating that at these combinations the dryer received almost equal energy input. Biomass mode trade-offs indicated that a lower flow rate (0.01 kg/s) was required for drying. Further, both solar-biomass and biomass modes must maintain a fuel feed rate of 0.001 kg/s for maximum exergy efficiency (solar-biomass: 80.21% ± 14.26%; biomass: 79.28% ± 10.38%) and drying air temperature of 333 K. Performance evaluation of the optimised system demonstrated its superiority compared to the unoptimised system.