A Computational Study of Perforated Helical Tube Inserted in a Double Pipe Heat Exchanger with Fluid Injection

Heat exchangers are still in high demand for the majority of industrial applications. A double pipe heat exchanger, also known as a DPHE, is a device that is used to transfer heat from hot to cold liquids, primarily water. It is therefore of great importance to discover new methods improving their thermal-hydraulic performance. In the current computational study, the focus will be on a helical turbulator constructed with small perforations and built inside the annulus of DPHE. First, our results are validated against their counterparts of an experiment conducted by others to examine the flow under the effect of a helical solid wire and/or global air blown inside the annulus. Second, four cases are introduced to the flow inside the helical tube only, two different mass flow rates for single and two phase flows. All findings suggest that the optimal performance comes from pumping some quantity of the working fluid inside the helical tube with roughly 600% and 45% increase in terms of overall heat transfer coefficient and thermal effectiveness, respectively, compared to that of non-perforated turbulator. Furthermore, for this proposed device, single-phase flow with or without oscillations outperforms two-phase and/or steady flow.