Testing the performance of a decker refractance window food dryer

Abstract

The decker RWD was designed and fabricated by Makerere University under the Bioinnovate Africa programme. The dryer comprises of three decks, each with a stationary mylar belt onto which the food is placed. During the process of refractance window drying, thermal energy from a shallow trough of hot water is transferred to wet material, normally in form of pulp, juice or slices. Infrared radiations from the hot water are transmitted to the food through the film such as a mylar belt thus causing rapid drying. The main aim of this project was to test the performance of the decker RWD with major emphasis on the quality and uniformity of drying as well as carry out an analysis and simulation of the water heating system. Eggplant slices were evenly distributed on each deck and allowed to dry to determine whether drying was uniform. The slices at the bottom deck dried fastest while the slices at the middle deck dried at the slowest rate. The water temperature per deck was recorded at intervals and it was also discovered to vary within the water troughs. The system was afterwards simulated using solid works to redesign it to ensure uniformity of the water temperature to allow for uniform drying.