Experimental Investigation of Convection Heat Transfer in a Helical Coil and Shell Heat Exchanger and Drag Reduction by Guar Gum

Abstract

The prime motive of this experimental study is to design a helical coil and shell heat exchanger and analyzing thermal performance based on convection heat transfer. Then, a polysaccharide, guar gum is used to lessen the drag force of cold water in helical pipe inside the heat exchanger, which ultimately lowers the amount of pumping power needed. The shell is made by rolling a square sheet and tube is formed by bending of straight pipe. Then, they are joined by spot welding to fabricate the complete heat exchanger. The rate of flow of cold fluid (tube side) is varied keeping the hot fluid flow rate (shell side) constant. Outlet and inlet temperatures of hot and cold fluids are measured to derive the heat transfer rate and overall convection heat transfer coefficient of cold fluid. Reynolds number and Nusselt number are estimated as two effective parameters of convection heat transfer. Heat transfer rate, overall heat transfer coefficient, Nusselt number and Reynolds number all are noticed to increase gradually with the rise in flow rate of cold fluid. Then, three different concentrations (100 ppm, 250 ppm and 500 ppm) of guar gum solution are used as cold fluid in tube of heat exchanger. The amount of pressure drop in tube found lower than the pure water for same flow conditions. So, mixing of guar gum into water decreases drag force in pipeline and lowers the power required to pump fluids through heat exchanger’s tubes that saves pumping cost. Maximum drop in pressure (50%) observed for maximum concentration.