Effects of two-equation turbulence models on the convective instability in finned channel heat exchangers

Abstract

Heat exchangers are multi-benefit thermal-devices, of wide use, as their structure varies with their scope of application. The development of channel configurations contained in these exchangers, and evaluation of their performance is the goal of many recent numerical and experimental achievements. Because of the high cost of such devices, many researchers had to follow CFD based computational methods instead of using experimental techniques. In this study, the hydrothermal structure of a finned channel heat exchanger is evaluated using the finite-volume based Ansys Fluent. Due to the complex structure of these channels, which contain overlapping transverse vortex generators, the flow develops into a turbulent structure that strongly influences the enhanced heat transfer. In this sense, various turbulence models are simulated to assess their numerical effect on the performance of the exchanger. Five different models are under experimentation which are (i) standard-, (ii) RNG- and (iii) realizable-case k-ε type models as well as (iv) standard- and (v) SST-case k-ω type models. As highlighted, the highest performance is reached with the SST-type k-ω, while the lowest one is that with the realizable-type k-ԑ.