Apr 132011
 

SOLAR CONVECTION GRAIN DRYER

INTRODUCTION

There is a need in many countries for an effective, inexpensive means for drying grain. Grain drying is a critical step in preparing grain for storage. Drying grain prevents germination of seeds, inhibits bacterial growth, and reduces insect damage. The drying process also drives off insects, while killing larvae and eggs. Since grain kernels become harder during the drying process, they are less susceptible to insect attack. Dried grain can also be stored in air-tight containers, protecting it from rodent and insect damage.

Currently, the most common method of grain drying is to spread the grain on slabs of concrete or on the ground to dry. This method, however, simply increases the chances of insect or weather damage. More modern grain-drying methods often consist of using equipment requiring some form of forced ventilation and/or fuel-burning heating systems. This causes a problem in many parts of the world because of the high cost and scarcity of fuels.

 

MATERIALS

* Drums, petroleum, 55-gallon (7)
* Lumber, 61cm X 122cm (34 meters)
* Lumber, 30.48cm X 61cm (20 meters)
* Plywood, .95cm thick (12 square meters)
* Particle board (27 square meters)
* Aluminum, corrugated (72 square meters)
* Plastic film, 4 mil thick (72 square meters)
* Netting, mosquito (244 square cm)
* Nails
* Tacks

TOOLS

* Saw
* Hacksaw
* Hammer

CONSTRUCTION OF THE DRYER
The Primary Collector Cut a 244cm X 6.7 meter piece of particle board to form the base of the collector.

Using 5.08cm X 10.16cm lumber, frame the particle board. Nail corrugated aluminum to the collector base to form the absorber plate.

The surface of the collector is covered with a sheet of plastic film.

The air passages at the foot and head of the collector should be 30.48cm long X 9.20cm high.

If plate glass is available, it can be used in place of the plastic film. The Drying Bin The base is made of plywood, 122cm long X 244cm wide X .95cm thick. It is framed with 5.08cm X 10cm lumber. The bin is 2.4 meters square and should be approximately 61cm high.

The drying bin is large enough to hold four drying trays. Each tray should be made from 2.54cm wooden framing, supporting nylon mosquito netting. The outside dimensions of each frame
should be 122cm X 122cm. The trays slide into the bin area on wooden guides. The roof of the bin is also made of plywood.

The Secondary Collector The secondary collector is built the same way as the primary collector. It should be 244cm wide x 4.8 meters long.

The Chimney The chimney is made from 55-gallon drums that are welded together, with the tops and bottoms removed from the five used or the chimney. Each of the drums should be painted black. The secondary collector is attached to the bottom of the
chimney where an inlet hole has been cut.

Two additional drums can be used to form the base of the chimney below the collector. The chimney extends 4.5 meters above the top of the
collector.

The completed dryer is shown on the following page.

<FIGURE 1>

57P03