Techno-economic analysis of a hybrid solar thermal-biogas powered dryer for fruit dehydration

Abstract

The global population as of 2024 stands at 8.2 billion and is projected to rise according to the United Nation, these pose sustainability challenges, particularly in food supply. Reducing postharvest losses, which account for about a third of food waste, is crucial, especially in developing countries, to meet future food demands without straining natural resources. This study aimed at determining the techno-economic viability of drying fruits using a hybrid solar thermal-biogas powered drying system. The objective is to; Develop and simulate a hybrid solar thermal-biogas powered tray/cabinet dryer to address intermittency and continuity, the work involved use of SolidWorks in model development and simulation. The design of experiment was done using Box Behnken under the response surface methodology found within design expert software. The parameters, which were optimized were air velocity at 2 m/s, material thickness at 7.5 mm, temperature at 60 °C and moisture content at 10.5 %. The prototype was built and tested. The findings showed continuity in drying was supported resulting into shorter residence time in comparison to open sun drying, moisture drive out from the sample was better in hybrid resulting into a loss of 78.3 % by weight compared to conventional open sun drying at 42.3 % for the same duration. The economic analysis was limited to key parameters which included ROI, NPV and a simple payback period, the result was very promising at 68.0 %, UGX 1,156,463/= and 1.47 years respectively for the hybrid dryer as compared to open sun drying with ROI of 28.0 %, NPV of UGX 5,602/= and 3.57 years. The sensitivity analysis revealed that the hybrid system’s economic performance is sensitive to changes in revenue and operating costs. A 10–20% decrease in revenue or a 10% increase in operating costs extended the payback period and reduced both ROI and NPV emphasizing the importance of maintaining stable revenues and controlling costs to sustain the system’s economic viability. The hybrid drying system shows potential as an efficient, costeffective solution for drying processes. While promising, sustaining its economic benefits requires managing costs and revenue. Further research is needed to test diverse crops, conditions, and industrial scalability