THE DEVELOPMENT OF A SOLAR DEVICE FOR CROP DRYING AND COOKING

Abstract

An absorber-type collector device for crop drying or cooking was fabricated and tested. It comprises of doubled-walled wooden box with a double glazed tight fitting lass lid. The gap between the walls of the box was stuffed with dry sawdust. A soot-coated, metal plate was attached to the bottom of the box as the heat absorber. Small pebbles also coated with soot, placed around the inner edges of the box act as heat storage medium. There were inlet and outlet ports with plastic pipes leading to and from the cooking chamber. Inlet air was made to pass through a container that was stuffed with dehydrating agent and from there, through a plastic tube into the chamber. There was a valve provided on the plastic tube. Air outlet was from the cooker through another plastic tube and leads into drying chamber. Both vales were closed when the device was operating as a cooker, and opened when it was operating as a dryer. It took 57minutes to cook beans, 37 minutes to cook yams and 43 minutes to cook rice, within the device, when there was bright sunshine. For the drying test, beef samples initially at 73% moisture content dried to 17% in 5 hours and cassava samples at 56% moisture content dried to 14% in 5 hours all in bright sunshine. The heat collection and conserving capacities of the device were found to be quite high ,with the maximum temperature reaching 134⁰c when in use as cooker. Temperature in the cooker was 74⁰c after 5 hours after shut down.