Performance Evaluation of a Hot-Air Groundnut Cabinet Dryer

Groundnut, also known as peanut, is an important source of food and oil, with the seeds being high in protein, fibre, and healthy unsaturated fats which are consumed in large quantities in most parts of the sub-Saharan Africa and the world at large. The post-harvest processing of peanut, most-especially drying that involves dehydrating the crop to safe moisture content for home and commercial purposes still need more attention as local drying prevailed in the country. An existing hot-air cabinet dryer was improved and evaluated for the drying of peanuts under the humid rainforest climate of Akure, Nigeria. The dryer was tested using three varieties of groundnut (red, white and kampala varieties), three drying air temperatures of 400C, 500C and 600C, two drying air velocities of 1.67 m/s and 2.78 m/s and two product loadings of 3 kg and 4.5 kg per batch. The thermal efficiency, drying rate, drying time and moisture loss were determined as the evaluation parameters of the dryer. The evaluation conducted revealed thermal efficiency range of 46% – 96% with average thermal efficiency of 71.31%. The drying rate of the dryer ranges from 0.36 kg/h – 0.21 kg/h, with an average drying rate of 0.28 kg/h at maximum and minimum drying time of 10 h and 6 h respectively. The moisture loss by the groundnut in the dryer ranges from higher value to lower value of 1.05 kg to 0.55 kg for the red variety; 5.4 kg to 1.01 kg for the white variety; and 1.02 kg to 0.55 kg for the kampala variety respectively. Results further revealed that the drying air temperature has the greatest effect on the thermal efficiency, drying rate, drying time and moisture loss as compared with the drying air velocity. It was further discovered that the drying rates of the three varieties were relatively equal. However, the drying rates were in the order: white > kampala > red variety. It can be concluded that the hot-air dryer handled the drying of the three varieties of groundnut optimally with higher performances and in conformity to standard practices.