Review Paper on the Use of Artificial Roughness inside a Solar Air Duct to Increase the Heat Transfer Rate Inside It

: The term solar air heating is a technology in which the radiant energy emitted by the sun is captured in an absorber and is used for space heating. Needless to say it is a renewable and pollution free method to produce space heating and when is used in commercial buildings or industries could be very cost effective. Improvement in the thermo hydraulic performance of a solar air heater can be done by enhancing the heat transfer. In general, heat transfer enhancement techniques are divided into two groups: active and passive techniques. Providing an artificial roughness on a heat transferring surface is an effective passive heat transfer technique to enhance the rate of heat transfer to fluid flow. In this paper, reviews of various artificial roughness elements used as passive heat transfer techniques, in order to improve thermo hydraulic performance of a solar air heater, is done. The objective of this paper is to review various studies, in which different artificial roughness elements are used to enhance the heat transfer rate with little penalty of friction.In this review paper, solar air heaters are discussed along with the problems associated, when use on large scale. Improvement in present technologies which are used for the manufacture of solar air heaters is the main area of focus in this paper and recent progress in enhancing the design of solar air duct are reported. Enhancement of effectiveness of the solar air heater which is in use today by applying small changes in the same so that the use of solar energy for space heating could be encouraged in lieu of using electricity was the main area of study in this paper. When being used for industrial purposes, however a lot of research work is still needed to be done.