Performance evaluation and economic analysis of inclined solar dryer for Capsicum annuum L. (Red chilli) drying

Abstract

This study presents an assessment of the performance and economic viability of solar dryers for drying perishable agricultural products. The dryer was constructed using locally sourced materials such as galvanized iron sheet, M.S. angle, glass, and S.S. wire mesh. The ability to tilt the dryer allows for optimal solar radiation absorption throughout the year in Jodhpur, India. It is well-established that a tilted surface captures more solar radiation compared to a horizontal plane, hence the utilization of a solar dryer in this research. A drying experiment was carried out in January 2023 using the dryer to dehydrate red chilli (Capsicum annuum L.). The maximum stagnation temperature inside the drying chamber was recorded at 65°C, which decreased to 55°C when loaded with 10 kg of chilli, while the outside ambient temperature was 26°C on a clear sky day (from 08:00 h to 18:00 h) in January 2023. Over the course of seven days, the moisture content of the chilli decreased from 80% (wet basis) to approximately 9%. The open sun drying method took 14 days for reducing the moisture content of red chillies to the same level. The dryer's thermal efficiency was calculated to be 16.25%. The economic analysis of the solar dryer indicated a high internal rate of return (IRR) of 82.5% and a short payback period of 1.50 years, highlighting its cost-effectiveness. The cost-benefit ratio was found to be 1.98, demonstrating the potential of solar dryers as a substitute for traditional drying methods. Economic parameters such as net present value (₹40220) and system annuity (₹5430) confirmed the economic feasibility of the system. Inclined solar dryers in remote or rural areas have the potential to significantly reduce post-harvest losses and carbon emissions. The adoption of solar dryers would greatly benefit farmers in the arid region of Rajasthan.