CFD Performance Prediction of a Parallel-Counterparallel Flow Heat Exchanger Used for the Treatment of Hypothermia

Abstract

The aim of this study is to investigate the use of computational fluid dynamics (CFD) in evaluating the thermal performance of a parallel/counterparallel flow heat exchanger used as part of a fluid warmer to treat hypothermia. The developed CFD model was validated in a parametric study using previously collected experimental data. The effects of heat exchanger length and inlet mass flow rate were considered. To more accurately represent the thermodynamic average temperature profile, the current CFD analysis evaluated outlet temperatures in terms of mean bulk temperature as opposed to the centerpoint temperature probe used in the experimental study. Despite this difference, the CFD results were found to agree well with the experimental values. As such, the CFD simulations are not only applicable to future design considerations but elicit further understanding of the thermal and hydrodynamic characteristics within the heat exchanger. Using the validated CFD model, thermal hydraulic entrance lengths and pressure drop within the semiannular geometry of the heat exchanger were investigated. CFD results of the semiannulus were compared to calculated values for a true concentric annulus. It was shown that the entrance length of a concentric annulus is generally longer than the semiannulus under laminar flow, and the difference is more prominent for increasing Reynolds number. Under both laminar and turbulent flow, the studied semiannulus of the hot water region demonstrated a greater pressure drop than a true concentric annulus with similar dimensions and flow conditions. The thermal and hydrodynamic properties revealed in this CFD analysis can be used to improve future design considerations, which may lead to improved hypothermia treatment protocols.