A novel active-mode indirect solar dryer for agricultural products: Experimental evaluation and economic feasibility

This article presents a novel active-mode indirect solar dryer consisting of highly efficiency through-flow evacuated tube collector for air heating. A DC fan powered with solar photovoltaic (PV) module is provided for forced air flow through this dryer. The dehydration chamber is of tray type with loading capacity of 6 kg-45 kg depending on the drying product. The dryer was evaluated to dry fenugreek leaves (Trigonella foenum-graecum) and turmeric (Curcuma longa) in semi-continuous mode; and respective overall thermal efficiency was found to be 34.1% and 23.6%. The respective thermal efficiency in open sun drying (OSD) was 5.7% and 5.4%. The quality of dried fenugreek leaves and turmeric was found better than OSD. Economics of the solar dryer indicate the capital cost is negligible in comparison to cumulative present worth of life cycle savings. The values are 211,262 INR (1 US$ = 74.57 INR) and 229,152 INR respectively for fenugreek leaves and turmeric; and capital cost of the dryer is only 50,000 INR. The low value of payback period also confirms economic viability of this dryer. The generalized economic curves have also been plotted. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

A novel active-mode indirect solar dryer with highly efficient through-flow evacuated tube collector for air heating was designed. The dryer can dry fenugreek leaves and turmeric in semi-continuous mode and shows good economic viability.