Solar drying
Practical Action
A much smaller tent dryer is shown below. Very similar to a cabinet dryer, it demonstrates the
overlap in designs between solar dryers):
Figure 4: A small solar tent dryer, Ghana.
Photo: Tony Swetman.
Figure 5: Large solar tent dryer, Ghana. Photo:
Tony Swetman.
Solar tunnel dryers
Many solar dryers employ the use of photovoltaic cells to power fans to blow air across the drying
area. Chief among this type of dryer is the Hohenheim dryer produced by Innotech in Germany.
By using a fan to create the airflow, drying time can be reduced substantially. Air flows across
an area usually painted black (the collector area) to absorb the sun’s heat and is blown across
trays containing the material to be dried. The diagram below shows the features of the dryer.
Solar
photovoltaic
panels
Air
inlet
Fan
Solar
thermal
collector
Drying
Tunnel
Concrete
block
substructure
Air outlet
Rolling bar
Metal frame
Figure 6: Solar tunnel dryer layout.
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