SPECIFIC HEAT OF SELECTED LEGUMES AND CEREAL GRAINS GROWN IN NORTH EASTERN NIGERIA

Thermal properties of agricultural materials are important parameters in the design and operation of thermal processing machines. This study focuses on the determination of specific heat of some staple crops at different moisture contents and temperatures, using the method of mixtures. The crops included maize, rice, millet, sorghum, groundnut, cowpea, locust bean and sesame seed. The temperature levels were 50oC, 60oC, 70oC and 80oC, while the four moisture levels employed ranged from 1.96-15.89% ( maize), 2.79-13.58% (rice), 2.27-23.55% (millet), 2.89-25.42% (sorghum), 1.57-29.02% (groundnut), 2.38%-30.70% (cowpea), 1.80%-12.20% (locust bean) and 2.37-21.5% (sesame). Results showed that the specific heat varied with grain and increased with increase in moisture content but decreased with respect to temperature increase. It ranged from 1689.1 to 3224.7J/kgK (maize), 1527.5 to 2661.4J/kgK (rice), 1689 to 3224.7J/kgK (millet), 1689 to 3224.7J/kgK (sorghum), 1689 to 3157.5J/kgK (groundnut), 1852 to 3224.7J/kgK (cowpea), 2523.7 to 3224.7J/kgK(locust bean) and 1689 ? 3224.7J/kgK (sesame). Regression equations that could be used to express the relationship existing between the specific heat and moisture content of the different crops were established.