Heat Transfer Analysis and Experimental Investigation of Nanofluid Flowing Through Circular Pipe with Helical Holed Strip

Abstract

Heat exchanger application in industrial and engineering application is quite popular. It is need to improve heat transfer rate, reduce pressure drop with respect to long term performance aspect of equipment. Most of heat exchanger used heat transfer fluid such as water, ethylene glycol, engine oil and propylene glycol have relatively low conductivity, when compared to the thermal conductivity of nanoparticle. The present dissertation work will be focused on heat transfer enhancement of heat exchanger using helical holed strip in circular pipe with working fluid as CuO nanofluid. Circular pipe helical holed strip geometry is not reported yet in the open literature. This geometry helps to generates swirl motion of fluid flow and disturbs the boundary layer to increase the effective surface area, residence time, reduce pressure drop and increase heat transfer coefficient. Experimental and Numerical investigations are performed using finite volume method to study turbulent convective heat transfer flows through a circular tube inserted with helical holed strip. The wall of tube was subjected to a constant temperature boundary condition. The continuity, momentum and energy equations are discretized and the SIMPLE algorithm scheme is applied to link the pressure and velocity fields inside the domain for plain tube. Three different twist ratios of 1.78, 2.05, 2.46 and three different types of holes 3.5mm, 4mm, 4.6mm were used to identify their effect on heat transfer, pressure drop and fluid flow characteristics through a circular tube inserted with helical holed strip geometries. The results indicate that the holed types of geometry increased up to 60% higher Nusselt number than plain pipe. 4 mm holed geometry achieved highest Nusselt number. But in other hand pressure drop is increases drastically due to turbulence effect. These results are compared with experimental results. For all the cases studied, the Nusselt number increased with the increase of Reynolds number and with the decrease of twist ratio of helical tape insert.