Small scale solar drying system

Abstract

Drying is an energy intensive process usually conducted in remote locations. Through the implementation of this system, the energy costs for drying may be reduced significantly as the energy source for drying is solar radiation. This system is also self- sustained. The solar radiation is to be harnessed through a solar collector that is designed to capture the radiation and concentrate it onto a smaller surface. The surface will then transfer the energy to the air flowing through it and into the drying chamber with the aid of a fan. The fan will be powered by a photovoltaic cell. The drying chamber will hold the biomass that needs to be dried. The objective is to reduce the moisture content of the material from 70% to 10%. Through collector design calculations, it was determined that with an aperture area of 1.27 m2, the collector can raise the absorber’s surface temperatures up to 206.4 oC. The absorber in turn may increase the air temperature to 59.5 oC. Four fins are fitted inside the absorber tube to assist with the heat transfer. The heated air will flow into the chamber to dry the material housed within it. The fan pushing the air through the collector and into the drying chamber will result in 50 air changes per hour in the chamber, assisting with the drying process. Through the calculations and design process, and the construction of the prototype, it is determined that the option for using solar energy for drying biomass is viable. Testing of the designed prototype was performed on April 4, 2014 and yielded a max exhaust air temperature of 74.0 oC, thus further demonstrating the potential of solar drying.