The use of solar evacuated tubes as an alternative method of drying

Abstract

Drying is one of the traditional methods of food preservation. It is performed in various ways which include sun drying (natural sun) and forced convection (diesel heaters and solar evacuated tubes). The sun drying method takes a long time and can be affected by seasons, thereby increasing the risk of spoilage of the food being dried. This may be avoided by using more efficient methods of drying that enable quick drying and can be used in all seasons. The aim of this study was to design and fabricate a heating system using solar evacuated tubes to produce heat that could dry farm products. Fabrication was done using waste aluminium sheets collected from Rivatex East Africa Limited. Tests were then carried out to determine the amount of heat required for drying, the arrangement of the solar evacuated tubes housing, and the quantity of air necessary for drying. Changes in temperature and relative humidity were also measured to determine the effectiveness of the dryer. And the arrangement of the solar tubes was parallel. The solar heat collector was able to heat the air from a temperature of 27.1 to 56.7°C, and relative humidity dropped from 52.4% to 36.5%. Results show that the designed solar dryer can be used as an alternative for natural sun drying.