Energy, exergy, economic and environmental (4E) analysis of passive and active-modes indirect type solar dryers while drying guava slices

The present study investigated the energy, exergy, economic and environmental (4E) analysis of passive and active mode indirect solar dryers (PMISD and AMISD) while drying guava slices in Warangal, India. The AMISD was developed by attaching a divergent duct with PMISD which consist of DC fans powered by PV panels at the entrance of the collector. The energy analysis revealed that average collector efficiency, drying efficiency and energy utilization ratio were 56.05, 5.42 and 13.27% and 65.37, 6.84 and 10.57% in PMISD and AMISD, respectively. The exergy efficiencies of the collector and drying chamber were 3.74 and 50.92% and, 2.39% and 57.03% in PMISD and AMISD, respectively. The economic analysis revealed that the payback period was noticed to be 2.24 and 1.38 years for PMISD and AMISD, respectively. The energy payback periods of PMISD and AMISD are 1.01 and 1.5 years, respectively. The CO2 emission, CO2 mitigation and maximum carbon credit earned for both the dryers were estimated at a lifetime of 35 years. The 4E analysis concluded that the performance of AMISD is higher compared to PMISD and both ISDs are economically viable and sustainable with a lower impact on the environment.