Evaluating the environ-economic and exergy-energy impacts of drying carrots in passive and active mode solar dryers

On the basis of exergy-energy and economic-environmental (4E) parameters, passive and active indirect solar dryers (PISD and AISD) were analysed and compared by drying carrot slabs. The PISD dryer was upgraded using fans run by photovoltaic panels those were placed at the gate of a divergent duct to make an AISD setup. Experimentally measured primary parameters were used to evaluate the 4E parameters. Accordingly, AISD had enhancement in collector and drying efficiencies of 19.27 and 11.86 % than PISD, respectively. Specific energy consumption (32.2 %) and moisture extraction rate (47.17 %) were better for AISD than PISD. Both setups were examined for their exergy parameters (mean efficiency, outflow, loss, and inflow). Exergy and environmental stability indicators such as sustainability index, environmental factor, waste exergy and improvement potential were calculated and distinguished for both dryers. AISD dryer gave better CO2 mitigation and carbon credit than PISD. The payback period of energy over 30 years lifespan was 1.33 and 1.78 years, and the economic payback period was 1.02 and 0.622 years, for PISD and AISD respectively. In comparison with PISD, the AISD achieved better in all the evaluated parameters. An uncertainty study was carried out for all the measured and estimated criteria. Results were compared with existing studies.