Thermal properties of African yam bean seeds as influenced by moisture content and temperature
The specific heat capacity, thermal conductivity and thermal diffusivity of African yam bean seeds were determined at temperatures ranging from 30 to 50oC and moisture contents from 9.6 to 30 % w.b. The initial moisture content of the seeds determined using the American Society Agriculture Engineering Standard (ASAE) test was 9.6 % (d.b). The specific heat capacity of African yam bean seeds, measured using copper calorimeter, increased from 2.035 to 2.816 KJ kg-1 k-1, as the moisture content and temperatures increased from 9.6 to 30 % (w.b) and 30 to 50oC respectively. The thermal conductivity of the seed was determined using the line heat source and ranged from 0.267 to 0.374 W m-1 k-1, and increased with moisture content increase. The thermal diffusivity of the seed ranged from 9.38 x 10-8 to 8.63 x 10-8 m2 s-1. These values indicate the ability of the African yam bean seeds to retain heat when processed. The regression models that could be used to adequately express the relationships existing between the thermal properties of the African yam bean seeds as influenced by temperatures and moisture contents were established.
Keywords: African yam bean seed, specific heat, thermal conductivity, moisture content, temperature
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