State of the Art solar air heater using Evacuated Tubes

The Sun is the source of all energy. The energy obtained from the sun is the most promising renewable energy sources since it is clean, safe and free. Applications of solar energy are commercially available and are used by millions of people in various parts of the world. One of the promising areas of the applications of solar energy is solar air heater. Solar air heaters are used for drying and space heating. The use of drying has been demonstrated as an application of air heaters. Villages in our district are mainly involved in agriculture and drying is one of the important processes in it. There are many problems in direct drying. Solar air heater is one of the best methods of drying the products in a hygienic manner. We have decided to construct a solar air heater with evacuated tubes, which increases the efficiency of the air heaters to a greater extent. It consists of the input unit, collector unit and drying unit. Air is passed through the input unit, and gets heated by the collector unit and circulated through the crop in the drying unit. Many agricultural products such as coffee, pepper, cereals, cardamom, potato slices and pappads were dried with it and its efficiency were calculated. Experimental results showed that its efficiency was increased to a greater extent (50-60%). The main advantage of this type is no insulation material is needed, which reduces the cost. This would be beneficial not only in conserving the fossil fuels, but also in protecting the environment by the emissions of harmful pollutants and green house gases