Converting Waste Agricultural Biomass into a Resource - UNEP

Transpired Collector Solar-Biomass Hybrid Cabinet Dryer 103
Philippines, Pilot Demonstration
Crop
Residue
Process
Equipment
Main Product
Biomass
Biomass residue
Gasification
hybrid solar-biomass dryer
Heat for drying
Technical Description of Technology
UPSL/UPD developed a hybrid solar-biomass dryer that incorporated several
innovative features. This drying system is distinct from the traditional solar
dryer designs due to use of an Unglazed Transpired Solar Collector (UTC) for
harnessing solar energy. The major use envisaged for this dryer was fish
drying. The dryer, which can accommodate 10 kg of fish, consists of a drying
chamber, a solar collector and a biomass stove/furnace.
Design details
The hybrid dryer was designed to operate with the UTC and the biomass
gasifier stove as the primary heat sources. This ensures continuous operation
of the hybrid dryer even during periods of inadequate solar radiation, as at
night. For the UTC operation, the solar radiation incident on the UTC heats
the perforated absorber plate. Convection transfers the heat absorbed by the
collector to the ambient air being drawn into the UTC plenum through the
perforations. The heated air from the collector is ducted into the heat
exchanger shell. The heated air inside the drying chamber passes through the
drying trays while picking up the moisture from the products being dried. The
moist air exits the drying chamber through the exhaust vent located on top of
the drying chamber. The continuous flow of air in the drying chamber has
been ascertained through the use of the vent mounted exhaust fan. Varying
the size of the opening of the exhaust vent through the use of dampers
regulates the airflow rate.
103 http://www.retsasia.ait.ac.th/booklets/Dissemination%20Booklets-Phase%20III/Tech%20pack-Drylow%20resl.pdf
224