![]() (g) Solar Cooking:Ī variety of fuel like coal, kerosene, cooking gas, firewood, dung cakes and agricultural wastes are used for cooking purposes. An important future application of solar furnaces is the production of nitric acid and fertilizers from air. Various property measurements are possible on an open specimen. This is especially useful for metallurgical and chemical operations. ![]() Heating can be accomplished without any contamination and temperature can be easily controlled by changing the position of the material in focus. ![]() The solar furnace is used for studying the properties of ceramics at extremely high temperatures above the range measurable in laboratories with flames and electric currents. In a Solar furnace, high temperature is obtained by concentrating the solar radiations onto a specimen using a number of heliostats (turn-able mirrors) arranged on a sloping surface. Spray drying of milk and fish drying are examples of solar dried animal products. Other agricultural products commonly solar-dried are potato-chips, berseem, grains of maize and paddy, ginger, peas, pepper, cashew-nuts, timber and veneer drying and tobacco curing. Solar energy operated dryer helps to overcome most of these disadvantages. In sun-drying sometimes, the produce is over dried and its quality is lost. Besides, reports reveal that it is not possible to attain very low moisture content in the sun-dried chilies.Īs a result, the chilies become prone to attack by fungi and bacteria. Moreover, the products being sun dried very often get spoiled due to sudden rains, dust storms or by birds. The present practice of drying chilies by spreading them on the floor not only requires a lot of open space and manual labour for material handling but it becomes difficult to maintain its quality and taste unless drying is done in a controlled atmosphere. Normally soft fruits are particularly vulnerable to insect attack as the sugar content increases on drying but in a fruit dryer considerable time is saved by quicker drying -minimizing gap the chances of insect attack. Solar drying, especially of fruits improves fruit quality as the sugar concentration increases on drying. These perforated trays or racks are carefully designed to provide controlled exposure to solar radiations. Agricultural products are dried in a simple cabinet dryer which consists of a box insulated at the base, painted black on the inner side and covered with an inclined transparent sheet of glass.Īt the base and top of the sides ventilation holes are provided to facilitate the flow of air over the drying material which is placed on perforated trays inside the cabinet. ![]() This is a traditional method of utilising solar energy for drying of agricultural and animal products. (e) Solar Drying of Agricultural and Animal Products: During periods of inclement weather when solar radiations are low then the requirement for water pumping is also relatively less as the transpiration losses from the crops are also low. The requirement for water pumping is greatest in the hot summer months which coincide with the increased solar radiations during this period and so this method is most appropriate for irrigation purpose. In solar pumping, the power generated by solar-energy is utilized for pumping water for irrigation purposes. Per liter distilled water cost obtained by this system is cheaper than distilled water obtained by other electrical energy-based processes. The condensed water flows down the sloping roof and is collected in the troughs placed at the bottom and from there into a water storage tank to supply potable distilled water in areas of scarcity, in colleges, school science laboratories, defense labs, petrol pumps, hospitals and pharmaceutical industries. The vapors produced get condensed to form purified water in the cool interior of the roof. ![]() Solar radiation passes through the covers and is absorbed and converted into heat in the blackened surface causing the water to evaporate from the brine (impure saline water). In this method, solar radiation is admitted through a transparent air tight glass cover into a shallow blackened basin containing saline water. The abundant sunlight in these areas can be used for converting saline water into potable distilled water by the method of solar distillation. In arid semi and or coastal areas there is scarcity of potable water. ![]()
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