Solar greenhouse drying: A review

Solar energy has been used for the preservation of agricultural produce since generations all over the world. Recent research on drying reveals the shortcoming of the open sun drying. In order to minimize the shortcoming of the open sun drying, various drying techniques are proposed. Among them previous effort on greenhouse dryer has been presented in this study. It can be used to do low temperature drying of cereal grains, fruits, vegetables, spices etc. The greenhouse dryer is operated in the two different modes of drying— natural convection and forced convection. Recently development of greenhouse dryers namely solar tunnel dryer, solar tent dryer, improved solar tunnel dryer, and roof type even span solar greenhouse dryer has been studied. An organized approach for the categorization of greenhouse dryers has evolved. A simulation model for drying performance proposed by authors has been studied. Products dried in the greenhouse dryer are found to be superior in quality as compared to those in open sun drying. In addition, the product is completely protected from external calamities such as rain, insects, and animals. All recent developments in greenhouse drying are emphasized in this communication.