ABSTRACT

This project studied thermal characterization of African star apple, water melon and pineapple to ascertain the thermal properties (specific heat capacity, thermal conductivity, and thermal diffusivity) for designing thermal systems. African star apple, water melon and pineapple were subjected to drying at temperatures 50°C, 60’C and 70°C and at different slice thickness of 5mm, 10mm and 15mmrespectively and drying parameters monitored, then used in determining the thermal properties, nutrient content and colour. These- thermal properties, nutrient content were used to determine the drying kinetics of products. The results showed a decreasing trend and indicate that the drying mechanism exhibits falling rate. The drying kinetics showed that at 5mm, each had shortest drying time while 15mm had the longest at drying time 50°C, 60°C and 70°C respectively. While 70°C gave the shortest drying time for all the slice thicknesses of 5mm, 10mm and 15mm respectively. From the drying kinetics, all the products (African star apple, water melon and pineapple) gave different moisture content at various temperatures and slice thicknesses. Thermal properties measured were specific heat capacity, thermal conductivity and thermal diffusivity. The specific heat capacity ofstart ranged between 3.91K]/Kg/°C -1.64 KJ/Kg/°C for fresh, 50°C, 60°C and 70°C respectively for African star apple, while pineapple from 3.76 KJ/Kg/’C - 3.48 KJ/KgTC and water melon from 5.25 KJ/KgTC - 0.537 KJ/Kg/°C for the respective temperatures. The thermal conductivity ofAfrican star apple ranged 0.365 W/ m°C - 0.704 W/mC, pineapple from 0.437 W/vtiC - 0.636 water melon from 0.396 l47/m°C - 0.537 W/m°C for the respective temperatures. Thermal diffusivity ofAfrican star apple ranged from 404.40(10-7)m2/s - 77.20(10-7)m2/s, pieapple fom 7.63(10-7)m2/s - 1.38 (10-7)m2/s and water melon from 10.36(10-7)m2/s - 1.55(10-7)m2/s for the respective temperatures