Energy and environmental analysis in an indirect solar dryer with flat coil inserted phase change material

Abstract

Solar energy, an extensively adopted renewable energy source, finds application in drying processes. This research investigates the performance of an Indirect Solar Dryer (ISD) using three conditions in a solar collector: without Energy Storage Material (ESM), with ESM featuring paraffin wax as Phase Change Material (PCM), and with ESM incorporating aluminum flat coil inserted PCM. The experimentation took place under autumn and summer climatic conditions for drying Coccinia grandis. Six experimental scenarios have been directed to analyze the drying kinetics, energy, and environmental impacts. The initial moisture content of a 2.5 kg product reduced from 2.31 kg of water (92.5 % w.b) to 0.25 kg of water (10 % w.b) within 10.25 h using ISD with ESM equipped with aluminum flat coil inserted PCM during summer climatic condition (Scenario 6). Scenario 6 achieved a maximum thermal efficiency of about 21.056 %. Environmental impact assessment revealed an Energy Payback Time (EPT) of 1.44 years for scenario 6. In scenario 6, CO2 emissions, mitigation, and carbon credits amounted to 24.11 kg/year, 20.12 tons, and $100.6 to $402.4, respectively, over the expected 35-year lifespan. The research suggests that the developed ISD stands as a potentially effective commercial drying method, demonstrating better performance in terms of energy efficiency and environmental sustainability.