Inducing Swirling Flow in Heat Exchanger Pipes for Reduced Fouling Rate

Fouling buildup in circular heat exchanger pipes is a common problem in the industry. Various methods have been proposed to increase the shear stress of the fluid near the pipe wall. This is known to reduce fouling rate, as well as increasing the heat transfer rate of heat exchangers. In this article, the effect of fouling-rate reduction is investigated by increasing friction in a circular pipe. This is done by inducing swirling flow at the pipe entrance, which in turn increases velocities close to the wall and consequently the shear stress. Results are obtained from a three-dimensional finite-volume computational fluid dynamics (CFD) code, where the pipe is modeled along with a swirling device at the entrance. Flow conditions are set to the laminar regime, where the effects of swirling flow are much more influential than in turbulent flow. It is concluded that considerable increase in friction can be obtained, but at the cost of increase in pressure drop.