DESIGN AND DEVELOPMENT OF SOLAR DRYER FOR HERBS

Abstract

Solar energy is very large, inexhaustible source of energy and it is one of the widely used renewable energy/unconventional energy sources. It will not only save conventional energy resources but also in maintaining environment pollution free. Whether drying crops, heating buildings, or powering a water pump. Drying or dehydration of material means removal of moisture from the interior of the material to the surface and then to remove this moisture from the surface of the drying material. Solar drying equipment would yield clean, dust free and good quality of agriculture produce. A dryer would make the drying process much faster as compared to than in open field drying normally adopted by the farmers. Moreover, the damage caused by birds, pests, rats and insects and by weather is reduced. hence the output of agricultural products is increased. In the present work, a natural convection indirect solar dryer is designed as per the requirement of herb Kutki which is to be dried and the weather condition of the installation site. Since this solar dryer has to be installed in a remote area so it should be easy to handle and can be maintained locally only. And as per the design a natural circulation solar dryer with its other components is fabricated. An experimental investigation has been carried out to study the drying process in the designed solar dryer. Ginger is selected for drying since it has the high moisture content almost same as herb Kutki. And the performance of the system is evaluated based on the observations and recorded data. In this experimental study, observations of the variations of temperature distribution with time have been made. The conductivity of aluminium absorber plate and surface painted with non-shining black board paint affects the inlet air temperature of flat plate collector, which further affects the useful heat gain by the collector. Solar dryer is made such that temperature inside the drying chamber is not going beyond the maximum allowable temperature at which drying of herb is permissible and herb will not lose its medicinal properties. The hourly variation in temperature at different locations of solar dryer and wind velocity are observed. The variation of solar radiation is also observed.