Enhancement of the Efficiency of Solar Air Heater by Using Artificial Roughness of Spiral Tubes Contained Hot Oil Flowing Inside the Tubes | Original Article
Generally heat transfer from fluid flowing to the stationary plate due to conduction process. After conduction further heat transfer will takes place that is due to convection process. Heat transfer will be reducing due to low thermal conductivity and due to relatively low air velocity. To overcome such type of a problem it is necessary to use artificial roughness to break laminar sub layer in order to reduce the thermal resistance and to increase the turbulence of flowing fluid result increase in heat transfer rate. In order to increase the heat transfer in solar air heater artificial roughness in spiral-pipe form are used. Inside the spiral pipes hot oil enforced to flow so it will create a further enhancement of heat transfer to the flowing air across the tubes. High frictional losses occur due to artificial roughness result high power required for the fluid flow. Turbulence results Due to artificial roughness which ultimately break the viscous laminar sub layer.