Design and development of solar air dryer for raisins

Mechanical engineering

Drying crops by solar energy is of great economic importance the world over, especially in India where most of the crops and grain harvests are lost to fungal and microbial attacks. These wastages could be easily prevented by proper drying, which enhances storage of crops and grains over long periods of time. India is blessed with abundant solar energy all the year round. The objective of this project is to modify design of a forced convection indirect solar dryer and its performance test on Grapes. The system consists of an air heating section (solar collector), a drying chamber and a centrifugal blower. In the process of drying, heat is necessary to evaporate moisture from the grapes. The solar collector is working as heat exchanger, which supply heat energy to air. Solar collectors are made of simple black painted aluminum corrugated plates. The solar air dryer consists of different components such as Solar Collector Plate, Air Blower and Insulating hot air Duct (wooden), the absorber plate is made up of aluminum and copper which has temperature range of 40 to 1200 C and its life is approximate 20 years. It is also highly recommended for photo-sensitive substance (crops) and have inherent tendency towards greater efficiency than direct solar drying.

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