Heat Transfer Enhancement Using a Pin Fin Heat Sink Filled with Metal Foams

Plate fin heat sinks (PFHS) are widely used to remove heat from the microelectronic devices. In the present study, a new type of compound heat sink, named as plate-pin fin heat sink (PPFHS), is employed to improve the air cooling performance. With CFD numerical method, PPFHSs with five forms of pin cross-section profiles (square, circular, elliptic, NACA 0050, and dropform) and PFHS were simulated. Two different length scales were adopted to evaluate the performance of six types of heat sinks, including PFHS. One of the length scales is commonly used by many investigators, which is two times of the channel spacing. The other length scale is suggested by volume averaging theory (VAT), which is four times of average porosity divided by specific interface. The influence of pin fin cross-section profile on the flow and heat transfer characteristics was presented by means of Nusselt number, pressure drop and overall efficiency. It is found that the Nu number of a PPFHS is at least 35% higher than that of a PFHS used to construct the PPFHS at the same Reynolds number no matter which length scale was used. It is also revealed that the heat transfer enhancement of square PPFHS is offset by its excessively high pressure drop, which makes it not as efficient as the other types of PPFHS. Circular PPFHS performs similar to the streamline shaped PPFHS when the Reynolds number is not too high. However, with the increase in Re the advantage of the circular cross-section diminishes. Using the streamline shaped pins, not only the pressure drop of the compound heat sinks could be decreased considerably, the heat transfer enhancement also makes a step forward. However, evaluating the performance of heat sinks by using the commonly used length scale, the benefit of streamline shaped types of PPFHSs is a little bit overstated. The VAT suggested length scale is more reasonable to do the performance comparison of different heat sinks, especially when it is difficult to provide a fair and physically meaningful basis for the comparison. In short, the present numerical simulation provides original information of the influence of different pin-fin cross-section profiles on the thermal and hydraulic performance of the new type compound heat sink and emphasizes the importance of choosing a proper length scale when evaluating heat transfer enhancement, which is helpful in the design of heat sinks.

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THERMAL PERFORMANCE OF VERTICAL HEAT SINKS WITH DIFFERENT PIEZOFAN ARRANGEMENTS

Transactions of the Canadian Society for Mechanical Engineering ◽

10.1139/tcsme-2013-0076 ◽

2013 ◽

Vol 37 (3) ◽

pp. 895-903 ◽

Cited By ~ 1

Author(s):

Jin-Cherng Shyu ◽

Jhih-Zong Syu

Keyword(s):

Heat Transfer ◽

Heat Transfer Enhancement ◽

Thermal Performance ◽

Heat Sink ◽

Heat Sinks ◽

Transfer Enhancement ◽

Pin Fin ◽

Enhancement Factors ◽

Vertical Heat

This study examines various effects on the heat transfer enhancement of several vertical heat sinks with a running piezofan. Both plate-fin heat sink and pin-fin heat sink having a 10-mm-high or 30-mm-high fin array were tested with either a vertical or a horizontal piezofan. Results show that the piezofan tip located at x/L = 0.5 usually yielded the highest heat transfer enhancement. Besides, heat transfer enhancement factors ranged from 1.2 to 2.4 for the present 10-mm-high plate-fin heat sink, and from 1.1 to 2.6 for the 10-mm-high pin-fin heat sink.

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Efficiency Improvement of Miniaturized Heat Exchangers

Fluids ◽

10.3390/fluids6010025 ◽

2021 ◽

Vol 6 (1) ◽

pp. 25

Author(s):

Iris Gerken ◽

Thomas Wetzel ◽

Jürgen J. Brandner

Keyword(s):

Heat Transfer ◽

Heat Transfer Enhancement ◽

Heat Exchangers ◽

Assessment Method ◽

Flow Path ◽

Transfer Enhancement ◽

Pressure Losses ◽

Pin Fin ◽

Additional Pressure ◽

The Impact

Micro heat exchangers have been revealed to be efficient devices for improved heat transfer due to short heat transfer distances and increased surface-to-volume ratios. Further augmentation of the heat transfer behaviour within microstructured devices can be achieved with heat transfer enhancement techniques, and more precisely for this study, with passive enhancement techniques. Pin fin geometries influence the flow path and, therefore, were chosen as the option for further improvement of the heat transfer performance. The augmentation of heat transfer with micro heat exchangers was performed with the consideration of an improved heat transfer behaviour, and with additional pressure losses due to the change of flow path (pin fin geometries). To capture the impact of the heat transfer, as well as the impact of additional pressure losses, an assessment method should be considered. The overall exergy loss method can be applied to micro heat exchangers, and serves as a simple assessment for characterization. Experimental investigations with micro heat exchanger structures were performed to evaluate the assessment method and its importance. The heat transfer enhancement was experimentally investigated with microstructured pin fin geometries to understand the impact on pressure loss behaviour with air.

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