Drying kinetics analysis of elephant foot yam and drying using heat pipe based solar dryer

Experimentation on heat pipe indirect passive solar dryer (SD) was conducted for identifying drying kinetics model of yam in SD and evaluate the performance of indirect SD. 8 thin layer models were applied to trays in SD and open sun drying (OSD). Average energy and exergy efficiency obtained as 46.84% and 6.69% for solar collector and 34.55% & 60% for SD. Product drying efficiency values in SD and OSD were 27.34% and 6.73% respectively. Moisture content of yam decreased to 4.8% from 82.5% in SD in 14 h and to 12.5% in OSD in 19 h. Effective moisture diffusivity values were 4.9 × 10⁻⁷ m²/s and 2.76354 × 10⁻⁷ m²/s for SD and OSD respectively. Convective and evaporative heat transfer coefficient varies between 1.63 and 1.88 and 11 to 33 W/m^2oC respectively. Page model represents drying of yam in SD and OSD.