Explain about the Solar Dryers?

There are so many different designs for solar dryers, these range from simple convection dryers, cabinet dryers, shelf dryers to more complicated semi-artificial dryers that involve some form of heat storage device. Common foods that would be dried by using solar dyers involve bananas, barley, coffee beans, pepper, peanuts, sweet potato, tea and wheat. A simple solar dryer can be built and the major parts of the solar dryer being;

a) Drying space, where the material to be dried is placed and in which the drying takes place.

b) Collector to convert solar radiation to heat.

c) Auxiliary energy source (optional).

d) Means for keeping drying air in flow. Could be a chimney or a fan

e) Heat storage unit (optional).

f)  Measuring and control equipment (optional).  

The drying method can be enhanced slightly by using some form of heat storage for when sunlight is not incident on the dryer as this means the drying period can be extended by using surplus energy and some degree of temperature control may be utilised. Efforts to enhance the solar drying process have included the make use of forced air circulation and combination with other drying processes, such as conventional drying processes and osmotic drying.