Solar Energy Dryer for Drying Agricultural Products
The drying of products using appropriate technology is necessary for the success of any enterprise or farm. The technology consists of two main components - the heat collector and the drying chamber, with a hot air tube connection. The collector is covered with one or two layers of 3-5mm thick glass. The absorber has a black painted surface to ensure an absorption of about 90% solar radiation and then converts it into thermal energy which radiates under the glass. The frame of the collector is made of metal and insulated with the surrounding ambient. The collector must be installed at the maximum position to be directly facing the sun, depending on the location. Efficiency of the collector is about 68- 71% due to the use of the double glass cover and good insulation. The drying chamber is made of metal and is heavily insulated. The drying capacity is 18kg for vegetables to 25kg for tuber, fruits and fish. The product is spread out on wire mesh trays that are designed and arranged for easy loading and unloading, as well as quick drying. The drying air is heated up at the collector and then enters the drying chamber. It then moves upward and passes across the food, which is spread on layers of vertically stacked trays. Air circulation is forced by ascending air due to natural convection. The airflow rate can be controlled by a centrifugal fan and air ventilation as required for removing the evaporated water. On the chamber side, there is an exhaust recycle tube connected from outlet to inlet with the purpose of saving thermal energy. With a low capacity for a drying chamber, the SD-25 is suitable for households in rural and island areas. The installation place should be installed at the maximum position to be directly facing the sun, not where there is shadow from 9am to 4pm. The solar dryer SD-25 was successfully tested under field conditions in three seasons with different climatic conditions. It can be used for drying almost all agricultural products and fish, and the drying time can be shortened by about 65% - 70%, compared with that of traditional sun drying. Other products with a low equilibrium moisture content like peanuts can also be dried to a moisture level for safe storage. During the drying process, the product is completely protected from rain, dust and insects, birds, rodents and losses are less than 1%, which is lower than any other drying method. The quality of products can be improved in terms of hygiene, safe moisture content, colour and taste. The technology is operated with clean and environmentally sound energy. It is easy to assemble, dismount and install and can be manufactured in place using locally available material and at a low cost. The payback period ranges from two to four years, depending on the rate of utilization.
Sector: Energy
Country: Viet Nam
Area of Application: Agro-Based product processing
Keywords: energy, agriculture, food processing
Environmental aspects: Cleaner Production
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Transfer Terms: Joint Venture , Technology Licensing
Target Countries: India
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Address: 41 DTD
City: HN
Country: Vietnam
Zip/Pin Code: 10000

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