Assessment of a beeswax-packed domestic solar dryer for sustainable bitter gourd drying: An experimental study

Solar dryers present a clean and affordable solution to food wastage which is one of the biggest concerns of the world. The highest contribution of domestic sector to the global food waste and lack of researches on small-scale solar dryers have created a need to develop sustainable and low cost domestic solar dryers. The present research aims to develop and analyse the output behaviour of a beeswax-packed domestic solar dryer (BDSD) for intermittent bitter gourd drying. The drying kinetics of bitter gourd slices and thermal, economic, environmental and exergetic performances of the BDSD have been evaluated with varying sample masses for passive and active drying conditions. The average final moisture content of the bitter gourd slices for passive and active conditions were found to be 3.26 and 3.93 % (wb), respectively. Midilli-Kucuk model exhibited the strongest fit to the bitter gourd drying behaviour under both the drying conditions. The total moisture evaporation, heat transfer coefficients, thermal efficiency, specific moisture extraction rate, savings for dried bitter gourd slices drying, CO₂ mitigation, carbon credit earned and exergy efficiency were found to increase while the drying rate, effective moisture diffusivity, specific energy consumption, costs for bitter gourd slices drying, payback period and energy payback time decreased as the sample mass increased under both drying conditions. The performance of the BDSD was found to be a linear function of sample mass under both drying conditions.