Solar dryers have some advantages over sun drying when correctly designed. They give faster
drying rates by heating the air to 10-30?C above ambient, which causes the air to move faster
through the dryer, reduces its humidity and deters insects. The faster drying reduces the risk
of spoilage, improves quality of the product and gives a higher throughput, so reducing the
drying area that is needed. However care is needed when drying fruits to prevent too rapid
drying, which will prevent complete drying and would result in case hardening and
subsequent mould growth. Solar dryers also protect foods form dust, insects, birds and
animals. They can be constructed from locally available materials at a relatively low capital
cost and there are no fuel costs. Thus, they can be useful in areas where fuel or electricity are
expensive, land for sun drying is in short supply or expensive, sunshine is plentiful but the air
humidity is high. Moreover, they may be useful as a means of heating air for artificial dryers
to reduce fuel costs (1)
Solar food drying can be used in most areas but how quickly the food dries is affected by
many variables, especially the amount of sunlight and relative humidity. Typical drying times
in solar dryers range from 1 to 3 days depending on sun, air movement, humidity and the type
of food to be dried.
Solar dryers have some advantages over sun drying when correctly designed. They give fasterdrying rates by heating the air to 10-30?C above ambient, which causes the air to move fasterthrough the dryer, reduces its humidity and deters insects. The faster drying reduces the riskof spoilage, improves quality of the product and gives a higher throughput, so reducing thedrying area that is needed. However care is needed when drying fruits to prevent too rapiddrying, which will prevent complete drying and would result in case hardening andsubsequent mould growth. Solar dryers also protect foods form dust, insects, birds andanimals. They can be constructed from locally available materials at a relatively low capitalcost and there are no fuel costs. Thus, they can be useful in areas where fuel or electricity areexpensive, land for sun drying is in short supply or expensive, sunshine is plentiful but the airhumidity is high. Moreover, they may be useful as a means of heating air for artificial dryersto reduce fuel costs (1)Solar food drying can be used in most areas but how quickly the food dries is affected bymany variables, especially the amount of sunlight and relative humidity. Typical drying timesin solar dryers range from 1 to 3 days depending on sun, air movement, humidity and the typeof food to be dried.
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