Chien Hung Chen

Bio: Chien Hung Chen is an academic researcher from National Chiao Tung University. The author has contributed to research in topics: Thermal resistance & Heat sink. The author has an hindex of 1, co-authored 1 publications receiving 10 citations.

A novel trapezoid fin pattern applicable for air-cooled heat sink

Abstract: The present study proposed a novel step or trapezoid surface design applicable to air-cooled heat sink under cross flow condition. A total of five heat sinks were made and tested, and the corresponding fin patterns are (a) plate fin; (b) step fin (step 1/3, 3 steps); (c) 2-step fin (step 1/2, 2 steps); (d) trapezoid fin (trap 1/3, cutting 1/3 length from the rear end) and (e) trapezoid fin (trap 1/2, cutting 1/2 length from the rear end). The design is based on the heat transfer augmentation via (1) longer perimeter of entrance region and (2) larger effective temperature difference at the rear part of the heat sink. From the test results, it is found that either step or trapezoid design can provide a higher heat transfer conductance and a lower pressure drop at a specified frontal velocity. The effective conductance of trap 1/3 design exceeds that of plate surface by approximately 38 % at a frontal velocity of 5 m s−1 while retains a lower pressure drop of 20 % with its surface area being reduced by 20.6 %. For comparisons exploiting the overall thermal resistance versus pumping power, the resultant thermal resistance of the proposed trapezoid design 1/3, still reveals a 10 % lower thermal resistance than the plate fin surface at a specified pumping power.

A Quick Overview of Compact Air-Cooled Heat Sinks Applicable for Electronic Cooling—Recent Progress

Abstract: This study provides an overview regarding enhancement of an air-cooled heat sink applicable for electronic cooling subject to cross-flow forced convection. Some novel designs and associated problems in air-cooled heat sinks are discussed, including the drawback of adding surfaces, utilization of porous surfaces such as metal foam or carbon foam, problems and suitable applicable range of highly interrupted surfaces (louver or slit) and longitudinal vortex generator. Though the metal foam may accommodate significant surface area, it is comparatively ineffective for air-cooling application due to its much lower fin efficiency, and this shortcoming can be improved by integrating with solid fin. For highly dense fin spacing (e.g., <1.0 mm), cannelure or grooved surface may be a better choice, and fin structure with periodic contraction and expansion may not be suitable for it introduces additional pressure drop penalty. The partial bypass concept, which manipulates a larger temperature difference at the trailing part of heat sink, can be implemented to significantly reduce the pressure drop. Through some certain niche operation, t the thermal resistance of the partial bypass heat sink may be superior to the conventional heat sink. The trapezoid fin surface featuring easier manufacturing and a smaller weight is shown to have competitive performance against traditional rectangular fin geometry. The IPFM (Interleaved Parallelogram Fin Module) design which combines two different geometrical fins with the odd number fins being rectangular shape, and parallelogram shape in even fin numbers, shows 8%–12% less surface than conventional design but still offers a lower thermal resistance than the conventional rectangular heat sink in lower flowrate operation. The cross-cut design shows appreciable improvements as compared to the conventional plate fin design especially in high velocity regime and the single cross-cut heat sinks are superior to multiple cross-cut heat sinks.

Investigation of the flow structure and heat transfer intensity of surfaces with split plate finning

Abstract: The authors use CFD modeling to study three types of heat exchange surfaces, i.e. a basic plate fin surface and two modified split plate surfaces – without rotation and with rotation of the split sections at an angle of 30° against the incoming air flow. Thermal aerodynamic characteristics of the studied heat exchange surfaces are obtained and verified with experimental data. The flow patterns are presented in three sections along the height of the channels in the finned area. An explanation is offered for the intensification of heat transfer in the modified heat exchange surfaces. It is shown how geometrical and operating parameters influence the heat transfer intensity and aerodynamic resistance. The results can be useful in designing cooling systems for electronics, particularly microprocessor and microlaser devices, power amplifiers of transmitting modules for radar systems, promising energy-saving solid-state light sources, power electronics for electric vehicles, equipment for aviation and space-rocket electronics with heat pipes.