Design & construction of a hybrid rice dryer with a heat recovery system.

Abstract

Rice (Oryz.ae sativa) is one of the most important foods in Uganda supplying as much as half of the daily nutritional requirements and calories to the Ugandan population. (MAFSC, 2009). About 80% office farmers in Uganda. are small stale farmers with acreage of less than 2 hectares who use P"O (JT drying methods such as open sun drying involving spreading of the crop on ground, tarpaulin, woven mat and road sides and also, to a small extent, it's done by artificial 'forced air dryers, these methods are associated. with proneness to weather conditions, long drying. time and high energy loses due to dryers' inefficient use of energy as almost all the energy input in the. dryer is wasted in the. atmosphere. This creates a need to design and construct a hybrid rice drier (fired by both solar and biomass) with a heat recovery system which can recover the energy that can be used to preheat the ambient air, and the heating system can then heat the preheated air to a final temperature. A solar-biomass energy system in this study was developed and achieved through data collection which involved literature surveys and reviews and internet surfing, designing the system components, constructing the prototype which was' tested and the results analysed. In this project, the solar concentrator gave temperatures of 35oC-40oC and the maximum was 45oC at noon while the biomass chamber gave temperature increment of 45oC and 47oC. The heat recovery system: recovered. 50% of the temperatures required for drying (35oC) Therefore, the dryer was 67.9% efficient and the heat recovery system was 55% efficient