Comparison of groundnut drying in simple and modified natural convection greenhouse dryers: Thermal, environmental and kinetic analyses

Present work compares the performances of simple and modified greenhouse dryers for groundnut drying. A latent heat storage unit (LHSU) filled with beeswax (PCM) was used to modify a natural convection greenhouse dryer. Groundnut samples were dried in a modified greenhouse dryer (MGHD) and simple greenhouse dryer (SGHD) in June 2019 at GJUST, Hisar, India. Convective heat transfer coefficient (h(c)) for groundnuts drying under MGHD and SGHD were in the range of 0.527-0.782 W/m(2) degrees C and 0.540-0.784 W/m(2) degrees C, respectively, while the respective evaporative heat transfer coefficient (h(e)) was found in the range of 18.60-197.63 W/m(2) degrees C and 1.178-243.172 W/m(2) degrees C. Moisture evaporated from groundnut sample drying under MGHD was 23.45% higher than in SGHD. Greenhouse energy and exergy efficiencies were found higher for MGHD. Specific energy consumption for groundnut drying was observed 67.16% lower in MGHD. Energy payback time was 2.28 and 1.27 years for MGHD and SGHD, respectively. CO2 mitigation and total carbon credit earned were found higher for MGHD. Moisture ratio for groundnut drying was predicted relatively well by the Midilli-Kucuk model. Experimental uncertainty was evaluated to vary from 1.88 to 2.03%.

Automated summary

This study compares the performances of simple and modified greenhouse dryers for groundnut drying. The results show that the modified greenhouse dryer has higher convective heat transfer coefficient, evaporative heat transfer coefficient, and moisture evaporation compared to the simple greenhouse dryer. The greenhouse energy and exergy efficiencies are also higher for the modified greenhouse dryer, while the specific energy consumption is lower. The energy payback time is shorter and the CO2 mitigation and total carbon credit earned are higher for the modified greenhouse dryer.