Design and construction of a desiccant air dryer for seeds and vegetables

Abstract

The object of this research is the design of an affordable desiccant dryer for local farmers for seed and vegetable drying. The subsequent increase in food production has led to an accompanying need for easy, safe, and affordable preservation methods. This has led to a substantial increase in the number of driers, which are expensive for local farmers to acquire. Seeds and certain vegetables do not do well, under the high heat used in most dryers for drying as the drying process is often used as a final production step before packaging and selling agricultural products. Desiccant drying is hygienic, low energy, low cost, and safe method of drying agricultural products without degrading them or reducing their nutritional quality. A desiccant air dryer for seeds and vegetables was designed and constructed, and its performance was tested using bitter leaves (Vernonia amygdalina). Desiccant dryer materials were carefully sourced and selected based on the cost of the materials, availability, strength, lightness (weight), and resistance to rust. The desiccant dryer chamber has external dimensions of 43 cm by 30 cm and internal dimensions of 28 cm by 25 cm. The drying chamber is divided into five layers; each layer is 48 cm by 44 cm with a total surface area of 0.2112 m².

Results showed significant moisture loss in the dried sample in 26 hours from 167 g to 54.1 g when compared with ambient air drying values. Proximate analysis of the desiccant dried bitter leaf higher values across all parameters when compared with the sample dried using ambient air. From the results obtained, it was therefore concluded that the desiccant dryer dried the samples faster than the common air-drying method. It was recommended that seed and vegetables should be dried in a desiccant dryer in other to increase shelf life and reduce perishability.