Pressure loss and heat transfer performance for additively and conventionally manufactured pin fin arrays

Abstract

Pin fin heat exchangers represent a common, viable means of keeping components cool and are widely used for electronics cooling and turbine airfoil cooling. Advancements in manufacturing technology will allow these heat exchangers to be built using new methods, such as laser powder bed fusion, a form of additive manufacturing. New manufacturing approaches, however, render a direct comparison between newly and conventionally manufactured parts meaningless without a good understanding of the difference in the performance. This research study investigated microchannel pin fin arrays that were manufactured using Laser Powder Bed Fusion and compared them to studies of pin fin arrays from the literature, which are representative of traditionallymanufactured pin fin arrays, where the pin and endwall surfaces exhibited much lower surface roughness. Pin fin arrays with four different spacings were manufactured and tested over a range of Reynolds numbers; pressure loss and heat transfer measurements were taken. Additionally, the test coupons were evaluated nondestructively and the asbuilt geometric features were analyzed. Measured surface roughness was found to be extremely high in each one of the microchannel pin fin arrays and was found to be a function of the pin spacing in the array, as was the shape of the pin itself; with more pins in the array came higher surface roughness and more distorted pin shapes. Comparisons between the smooth pin fin arrays from literature and the rough pin fin arrays from the current study showed that the high surface roughness more strongly affected the friction factor augmentation than it did the heat transfer augmentation relative to the smooth pin fin arrays.

Performance analysis of microchannel with different pin fin layouts

“…However, the overall performance is best among all the layout considered. The staggered pin fin layouts both in case b and case c are intermediate in terms of ease of manufacture and performance when compared with case a and case d. The results in the present work are validated with similar work from the literature . Moreover, along with the change in the layout, the inlet velocity of the coolant fluid and axial distance between the pin fins is observed to have a cumulative effect on the microchannel performance, and it is different for different layouts.…”

“…Tang et al numerically investigated the influence of inlet/outlet positions and header forms on the flow and thermal performance of microchannel heat sinks and found that the performance of I‐type inlet‐outlet with a rectangular header is better compared with other cases. Kirsch and Thol investigated the microchannel pin fin arrays manufactured using Laser Powder Bed Fusion to study their pressure drop and heat transfer characteristics. The effect of pin fin geometry was numerically analyzed by Jadhav et al in terms of the Nusselt number and pressure drop and observed that the elliptical pin fins experience minimum pressure drop.…”

Improvement of heat transfer through fins: A brief review of recent developments

“…Their results showed the validity of the regression model and the effectivity of the optimal parameters. An experimental investigation on heat transfer performance and pressure drop of conventionally and additively fabricated pin‐fin arrays was performed by Kirsch and Thole 19 . When rough and smooth fin surfaces were compared, it showed that the rough surface highly affects the friction factor as well as augments heat transfer rather than smooth pin‐fin arrays.…”

Performance Assessment of a Three-Dimensional Printed Porous Media Produced by Selective Laser Melting Technology for the Optimization of Loop Heat Pipe Wicks

“…Therefore, a bi-exponential adjustment of the experimental data was done to obtain the analytical form of the liquid height, in a similar way to [29], with a view to the performance of further comparative capillary tests. This adjustment predicted values within the ±5% threshold.…”