Experimental Study on The Effect of Skin Friction Drag and Convective Heat Transfer for Pseudoplastic & Viscoelastic Fluid Flow.

Abstract

Drag reducing agents (DRAs) has a huge impact and a major concern in the engineering field and industrial applications. It makes the fluid flow turbulent to laminar, dampens eddy and reduces head loss by up to a certain limit and saves pumping energy costs. Viscosity is the property which dampens eddy due to viscous effect increases the fluidity up to a certain limit. Pseudoplasticity is the shear thinning effect that decreases viscosity when flowrate increases. So for viscoelastic effect we can increase the concentration up to a certain limit to reduce head loss but during flow due to pseudoplastic effect the viscosity will start decreasing which is negative effect. So these combined effect is studied to reduce skin friction drag in pipline and save energy cost which will be convenient for food industry, chemical and medicine industry. In this investigation, investigation is carried out for 0.3 g/L, 0.2 g/L and 0.15 g/L of xanthan gum in turbulent flow to observe the pressure drop and heat transfer rate. The study reveals that after increasing viscosity the pressure drop reduced significantly. Conversely the heat transfer rate also reduced due to poor mixing effect. A higher performance and less vibration of pump was also observed. It was concluded that frictional pressure drop was reduced up to 85% and heat transfer rate reduced up to 90% by increasing the concentration of the DRA(drag reducing agent) up to 0.3 g/L at 10 LPM than the pure water or base fluid as working substance on double pipe heat exchanger. As the heat transfer rate reduced up to 90% with reducing pressure drop so another aim of the study was to establish a concentration and flowrate for which heat transfer rate is maximum and it was found at concentration of 0.15 g/L of DRAs(drag reducing agents) at 22 LPM(maximum flowrate at this setup).