New structure-performance relationships for surface-based lattice heat sinks

The use of a micro heat sink is an effective means of solving the problem of high-power chip heat dissipation. Diamond/Cu composites exhibit high thermal conductivity and a linear thermal expansion coefficient that is compatible with semiconductor materials, rendering them ideal micro heat sink materials. The aim of this study was to fabricate diamond/Cu and Cu separately as heat sinks and subject them to flow boiling heat transfer experiments. The results indicate that the diamond/Cu heat sink displayed a decrease in wall superheat of 10.2–14.5 °C and an improvement in heat transfer coefficient of 38–51% compared with the Cu heat sink under identical heat fluxes. The heat sink also exhibits enhanced thermal uniformity. Secondary diamond particles are incorporated into the gaps of the main diamonds, thereby constructing a three-dimensional heat conduction network within the composite material. The diamond network enhances the internal heat flux of the material while also creating more nucleation sites on the surface. These increase the boiling intensity of the diamond/Cu heat sink, leading to better heat transfer performance. By combining the transient thermal model with computational fluid dynamics, a heat transfer model based on the diamond/Cu heat sink is proposed. The efficient heat dissipation capability of diamond/Cu heat sinks can lower the working temperature of microelectronic devices, thereby improving device performance and reliability during operation.

The drive for small and compact electronic components with higher processing capabilities is limited by their ability to dissipate the associated heat generated during operations, and hence, more advanced heat sink designs are required. Recently, the emergence of additive manufacturing techniques facilitated the fabrication of complex structures and overcame the limitation of traditional techniques such as milling, drilling, and casting. Therefore, complex heat sink designs are now easily realizable. In this study, we propose a design procedure for mathematically realizable architected heat sinks and investigate their performance using the computational fluid dynamics (CFD) approach. The proposed heat sinks are mathematically designed with topologies based on triply periodic minimal surfaces (TPMSs). Three-dimensional CFD models are developed using the starccm+ platform for uniform heat sinks and topologically graded heat sinks to study the heat transfer performance in forced convection domains. The overall heat transfer coefficient, surface temperature, and pressure drop versus the input heat sources as well as the Reynolds number are used to evaluate the heat sink performance. Moreover, temperature contours and velocity streamlines were examined to analyze the fluid flow behavior within the heat sinks. Results showed that the tortuosity and channel complexity of the Diamond solid-networks heat sink result in a 32% increase in convective heat transfer coefficient compared with the Gyroid solid-network heat sink which has the comparable surface area under the examined flow conditions. This increase is at the expense of increased pressure drops which increases by the same percentage. In addition, it was found that expanding channel size along flow direction using the porosity grading approach results in significant pressure drop (27.6%), while the corresponding drop in convective heat transfer is less significant (15.7%). These results show the importance of employing functional grading in the design of heat sinks. Also, the manufacturability of the proposed designs was assessed using computerized tomography (CT) scan and scanning electron microscopy (SEM) imaging performed on metallic samples fabricated using powder bed fusion techniques. A visible number of internal manufacturing defects can affect the performance of the proposed heat sinks.

Heat transfer augmentation in heat sink with fin-bars inserted in cooling channel

본 실험에서는 실제 태양광 발전용 인버터의 냉각에 사용할 2개의 압출형과 2개의 압입형 히트싱크의 방열 성능을 평가하였다. 두 압입형 히트싱크의 핀의 개수는 62개와 98개, 전열면적은 2.8 ㎡, 5.3 ㎡이고, 두 압출형 히트싱크의 핀의 개수는 38개와 47개, 전열면적은 1.8 ㎡, 1.9 ㎡이다. 압입형 히트싱크의 방열율은 각각 82.7 %, 86.3 %, 압출형 히트싱크의 방열율은 각각 79.6 %, 81.6 %로 측정되었다. 각 히트싱크의 방열성능 평가결과에서 히트싱크의 전열면적이 증가할수록 방열율이 증가하는 경향을 보였다. 압입형인 S-62 히트싱크는 압출형인 E-47 히트싱크 보다 전열면적이 47.4 % 증가하였음에도 불구하고 방열량은 1.3 % 증가하는데 그쳤다. 이는 압출형의 우수한 전열성능 때문인 것으로 판단된다. 또한 압입형인 S-98 히트싱크는 동일한 압입형인 S-62 히트싱크에 비해 전열면적이 89.3 % 증대되었음에도 방열량 증가는 4.4 %에 불과하여 전열면적에 대한 최적화가 필요함을 알 수 있었다.

Heat sinks have been widely used in cooling systems due to their high heat transfer efficiency. In this study, the thermal performance and fluid flow characteristics of conventional and triply periodic minimal surfaces (TPMS)-based heat sinks were investigated through detailed computational fluid dynamics (CFD) simulations. The results indicate that the TPMS-based heat sink, particularly SplitP, exhibited the highest heat transfer rate at 0.0082 W, which is more than ten times the rate of the conventional design (0.00076 W). The Gyroid structure also showed impressive performance with a 0.0022 W heat transfer rate. Furthermore, the performance evaluation criterion (PEC) was used to quantify the effectiveness of each design in terms of heat transfer efficiency. The PEC values obtained were 1.00 for the conventional heat sink, 1.17 for the Gyroid heat sink, showing a 17% improvement, and 1.43 for the SplitP heat sink, showing a 43% improvement. The findings from our study will inform future heat sink design, contributing to the development of more efficient cooling solutions by emphasizing the critical role of PEC in performance evaluation.

High-performance compact heat sinks have been developed for effective cooling of high-density LSI packaging. Heat transfer and pressure loss characteristics of the heat sinks in both air-cross flow and air-jet cooling have been experimentally studied. The present heat sinks were of plate-fin and pin-fin arrays with a fin pitch of 0.7 mm. The plate-fin heat sinks had higher cooling performance than the pin fin heat sinks in the range of large air flow rate both in air-cross flow and air-jet cooling. The thermal conductance in cross-flow cooling was 20 or 40% larger than that in jet cooling. The correlation of Colburn j-factor/Fanning friction factor vs. the Reynolds number for the present heat sinks was found to be very close to that of a conventional large size heat exchanger.

Experimental investigation on heat transfer characteristics in circulatory flash vaporization of aqueous NaCl solution

Modeling heat transfer properties in an ORC direct contact evaporator using RBF neural network combined with EMD

Direct contact heat transfer between two immiscible liquids flowing in a horizontal concentric annulus

High flux boiling in low flow rate, low pressure drop mini-channel and micro-channel heat sinks

The Cooling performance of a plate fin-type heat sink equipped with a cooling fan was investigated experimentally. The heat sink was 80 mm long, 43 mm wide, and 24 mm in height, (including the 4-mm-thick base). The cooling fan was 40×40×15 mm and was set to direct the air flow vertically at the downstream half of the heat sink. We focused on the influence of the height that the fan was set at, which we varied from 5 to 20 mm, had on the heat transfer coefficient of the heat sink. The maximum value of the heat transfer coefficient was achieved at a setting height of 5 mm. At this heigth, the volumetric heat transfer coefficient was 1.8 times as high as with a parallel flow under the same fan power. This indicates that the cooling performance of heat sinks with cooling fan can be improved by using this kind of compact structure.

Study on spray cooling characteristics of dry ice particles for IGBT in high-speed trains{fr}Etude des caractéristiques de refroidissement par pulvérisation des particules de glace sèche pour l'igbt dans le train à grande vitesse

An experimental investigation for the time dependent volumetric heat transfer coefficient of the bubbles type, three-phase direct contact condenser has been carried out utilising a short column (70 cm in total height and 4 cm inner diameter). A 47 cm active height was chosen with five different mass flow rate ratios and three different initial dispersed phase temperatures. Vapour pentane and constant temperature tap water as dispersed and continuous phases were implemented. The results showed that the volumetric heat transfer coefficient decreases with increased time until it almost reaches its steady state conditions. A sharp decrease in the volumetric heat transfer coefficient was found at the beginning of the operation and, diminished over a short time interval. Furthermore, a positive effect of the mass flow rate ratios on the volumetric heat transfer coefficient was noted and this was more pronounced at the beginning of the operation. On the other hand, the volumetric heat transfer coefficient decreased with an increase in the continuous phase mass flow rate and there was no considerable effect of the initial dispersed phase temperatures, which confirms that latent heat transfer is dominant in the process.

Forced convective heat transfer of nanofluid as a coolant flowing through a heat sink: Experimental and numerical study

Convective heat transfer performance of airfoil heat sinks fabricated by selective laser melting