A Study of the Influence of Fin Parameters on Porous-Medium Approximation

Abstract

The porous-medium approximation (PM) approach is extensively employed in large-quantity grid simulations of heat exchangers, providing a time-saving approach in engineering applications. To further investigate the influence of different geometries on the implementation of the PM approach, we reviewed existing experimental conditions and performed numerical simulations on both straight fins and serrated fins. Equivalent flow and heat-transfer factors were obtained from the actual model, and computational errors in flow and heat transfer were compared between the actual model and its PM model counterpart. This exploration involved parameters such as aspect ratio (a*), specific surface area (Asf), and porosity (γ) to evaluate the influence of various geometric structures on the PM approach. Whether in laminar or turbulent-flow regimes, when the aspect ratio a* of straight fins is 0.98, the flow error (δf) utilizing the PM approach exceeds 45%, while the error remains within 5% when a* is 0.05. Similarly, for serrated fins, the flow error peaks (δf > 25%) at higher aspect ratios (a* = 0.61) with the PM method and reaches a minimum (δf < 5%) at lower aspect ratios (a* = 0.19). Under the same Reynolds numbers (Re), employing the PM approach results in an increased heat-transfer error (δh)with rising porosity (γ) and decreasing specific surface area (Asf), both of which remained under 10% within the range of this study. At lower aspect ratios (a*), the fin structure becomes more compact, resulting in a larger specific surface area (Asf) and smaller porosity (γ). This promotes more uniform flow and heat transfer within the model, which is closer to the characteristics of PM. In summary, for straight fins at 0 < a* < 0.17 in the laminar regime (200 < Re < 1000) and in the turbulent regime (1200 < Re < 5000) and for serrated fins at 0 < a* < 0.28 in the laminar regime (400 < Re < 1000) or 0 < a* < 0.32, in the turbulent regime (2000 < Re < 5000), the flow and heat-transfer errors are less than 15%.

Numerical Study of Fluid Flow in a Gyroid-Shaped Heat Transfer Element

“…A larger heat exchange area allows heat to be transferred between hot and cold media over a larger surface area; also, the parameter of the surface area enters the calculation of thermal resistance, a reduction of which will increase the total heat flux transferred through the surface area, as described by Mousa et al [8], Kanojiya et al [9], and Leal et al [10]. The enlargement is mainly done by modifying the geometrical parameters in the form of introducing different forms of fins, plates, and slotting [11,12] or by introducing a porous heat-conducting element [13,14], for example, in the form of a three-dimensional lattice, honeycomb structure, or metal foam [15][16][17][18]. The presented paper focuses on the evaluation of the possibility of using the concept of a three-dimensional element increasing the heat exchange surface of heat exchangers, heat accumulators, heat sinks, etc.…”