Heat Flux and Exergy Analysis of a Modified Passive Pot‐in‐Pot Jute‐Charcoal Cooling Blanket for Extending the Shelf Life of Fruits and Vegetables

This study presents the development and evaluation of a modified passive pot‐in‐pot evaporative cooling system, utilizing a jute–charcoal blanket to enhance the preservation of fruits and vegetables in rural areas. Future research could expand the applicability of this technology across diverse crops, seasons, and geographic regions to enhance generalizability. Its performance was assessed through experimental trials and thermodynamic analysis. A novel method was employed to determine thermal efficiency by iteratively analyzing conductive, sensible, and latent heat fluxes. Experimental results showed that the system reduced temperature by 1°C–14°C and increased relative humidity by 23%–65%, corresponding to cooling efficiencies between 22.7% and 96.3%. The jute–charcoal blanket maintained an average internal temperature of 22.89°C, with fluctuations limited to ±4°C, despite ambient temperature variations of up to 14°C. The average thermal efficiency ranged from 50% to 61%, while cooling capacity varied between 0.84 and 2.32 kW. Specific water consumption ranged from 0.0012 to 0.00157 kg s −1 m −2 °C −1 . Exergy analysis indicated losses between 0.63 and 0.83 kW, with exergy efficiencies of 20.4%–34.6%. The sustainability index ranged from 1.017 to 10.78, indicating relatively sustainable operational performance. Overall, the system demonstrates strong potential as a low‐cost, energy‐efficient, and environmentally friendly cooling solution for smallholder farmers and rural traders.