Design and Evaluation of Solar Grain Dryer with a Back-up Heater
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Date
2014-04Author
Tonui, K S
Mutai, E B K
Mutuli, D A
Mbuge, D O
Too, K V
Language
enMetadata
Show full item recordAbstract
The aim of the study was to design and construct a solar grain dryer integrated with a simple biomass
burner using locally
available materials. This was to address the limitations of the natural sun drying for example
drying exposure, liability to pests and rodents, over
-
dependence on sun and escalated cost of mechanical dryers.
This became beneficial especially in reducing po
st
-
harvest losses as well as helping in the preservation of
agricultural product. The dryer is composed of solar collector, drying chamber, back
-
up heater and airflow system.
The design was based on the study area of Mau summit located in Nakuru County, Ke
nya. The average ambient
conditions were 26°C air temperature and 72% relative humidity with daily global solar radiation incident on
horizontal surface of about 21.6 MJ
/
m
2
/
day
. A minimum of 3.77 m
2
solar collector area was required to dry a batch
of 100 kg maize grain in 6 h with natural convection from the initial moisture content of 21% to final moisture
content of 13% wet basis. A prototype dryer designed was fabricated with minimum collector are
a of 0.6 m
2
and
used in the experiment
.
Forced convection was employed to reduce drying time.
The thermal efficiencies of the solar
and solar assisted dryer were 39.9 and 57.7%, respectively.
The back
-
up heating system improved the efficiency of
the dryer
by 17.8% and reduced drying time substantially
Citation
Tonui, K. S., Mutai, E. B. K., Mutuli, D. A., Mbuge, D. O., & Too, K. V. (2014). Design and Evaluation of Solar Grain Dryer with a Back-up Heater. Research Journal of Applied Sciences , Engineering and Technology 7(15), PP. 3036 - 3043Publisher
University of Nairobi