Drying kinetics and thermo-economic analysis of drying hot water blanched ginger rhizomes in a hybrid composite solar dryer with heat exchanger

This research aimed to examine the need of adding hot water blanching pre-treatment on the drying of ginger rhizomes using a hybrid solar-dryer with paraffin liquid as thermal storage infused into a copper tube to form a compact heat exchanger. Blanching duration quickened the drying rate of the ginger rhizomes and the average drying rate for blanching at 90 s, 60 s, 30 s and un-blanched ginger varied between 0.0147 kg/h to 0.0245 kg/h at a sensible heat ratio of 4.12 × 10⁻⁵ to 2.53 × 10⁻³. The optimal drying rate varied from 0.01161 kg/h to 0.0263 kg/h for all treatment at a collector temperature range of 39.5 °C-40.5 °C and collector efficiency range of 14.3%-30%. The logarithmic model better predicted the drying kinetics of un-blanched and blanching for 30 s with an R² value of 0.9875 and 0.97247 respectively while the modified Henderson and Pabis model better predicted drying of blanched ginger rhizomes at 60 s and 90 s with R² values of 0.96252 and 0.98188 respectively. Using the hybrid solar dryer instead of artificial dryers with fossil energy sources can save about $75.731 to $757.31 of the running cost as the usage increased from 10 to 100%. The payback period decreased from 2.88 years to 0.31 years as the rate of usage increased from 10 to 100%. Using the presented solar dryer instead of coal, diesel or grid base electricity can prevent 15.96 to 186, 7.62 tones of CO₂ from entering the atmosphere. The earned carbon credit if the dryer is to be powered by coal, diesel or grid base electricity were $ $6245364, $27080.52, and $231.45 per year respectively which can be used to compensate other non-renewable energy sources deployed within an energy enterprise.