• Clean Technology
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• v.14 no.4
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• pp.265-270
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• 2008

In this study, the flow and heat transfer of the aligned pin-fin array of the air cooling module for electronic packaging application were numerically analyzed with various fin shapes. The geometric cross-sectional shapes of pin-fins considered in this study were ellipse, wing and circle. The fins had same cross-sectional area and height, but they had different surface areas. As the results, the surface area, the heat transfer coefficient, and the heat transfer performance of pin-fins greatly depended on their shapes. Of the three types of pin-fins, the wing type pin-fin with suitable shape produced the best heat transfer performance. This result implies that the cooling capacity of the pin-fin cooler can be significantly enhanced only by the change of fin shape without increasing air flow-rate or fin density.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.5
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• pp.43-55
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• 2020

The effect of cutted pin in front of pin-fin array was analyzed for increasing the cooling performance of gas turbine blade. The numerical simulations were conducted to figure out the flow and thermal characteristics. The base case which is staggered pin-fin array, cut pin case 1 which has X₂/D_p=1.25 cut pin and cut pin case 2 which has X₃/D_p=1.75 cut pin were compared. The results showed that cut pin increases the strength of the horseshoe vortex which occurred at the leading edge of pin-fin array. Furthermore, the wake effect is reduced at the trailing edge of pin-fin array. As a result, the heat transfer distribution on the endwall increases. However, the friction factor increases owing to the installation of cut pin, but the thermal performance factor is increased maximum 23.8% in cut pin case 2. Therefore, installation of cut pin will be helpful for increasing the cooling performance of pin-fin array of gas turbine blade.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.2
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• pp.224-231
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• 2011

Heating and/or cooling of the channel with pin-fin structure is a promising choice for the efficient heat transfer. Complex pin-fin structure shows highly irregular behavior like porous media. This study shows the numerical analysis on the characteristic of heat transfer and pressure drop of a channel with pin-fin structure. It predicts the experimental data quite well at the high porosity region with large diameter. Low porosity activates the rigorous flow disturbance and, consequently, the enhanced heat transfer. However, the concept of optimum design should be carefully reviewed because the pressure drop is also increased with decreasing porosity at low porosity region.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.3
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• pp.35-43
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• 2019

In this study, a guide vane with varying positions and incidence angles was adopted to a pin-fin channel to analyze the change in thermal performance and pressure loss characteristics. A numerical analysis was conducted to investigate the effect of incidence angles and positions on heat transfer and flow characteristics at Re =1400. The results of it were compared those of a pin-fin channel without a guide vane. In case 1 when the incidence angle is $0^{\circ}$, the heat transfer performance is maximized and improved by approximately 5% when compared to the pin-fin channel without the guide vane. In case 2 when the incidence angle is $10^{\circ}$, the pressure loss is minimized and decreased by approximately 1.9% when compared to the pin-fin channel without the guide vane.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.4
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• pp.28-34
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• 2019

In this study, pin-fin arrays, which are widely used for cooling turbine blades, were studied. The vortex generator in pin-fin arrays is located in front of the circular tube. The cross-section of the vortex generator is NACA-9410. The purpose of this study is to analyze heat transfer performance and flow characteristics of pin-fin arrays. The position of vortex generator is changed with the vertical flow direction on the bottom wall. Pin-fin arrays were calculated with 6000, 10000 and 15000 Reynolds number. The commercial program ANSYS v18.0 CFX and the turbulence model $k-{\omega}$ SST were used. As a result, the heat transfer performance increased up to 5.8% and pressure loss increased less than 1%.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.1
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• pp.35-39
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• 2013

This paper reports numerical study results with respect to the thermal behavior of a natural convection cooled hybrid fin heat sink (HFH). The HFH consists of hybrid fins, hollow pin fins integrated with plate fins. The thermal performance of the HFH was numerically investigated by employing a commercial CFD software package and compared with that of the pin fin heat sink (PFH). Numerical study has found that array-based and mass-based heat transfer coefficients of the HFH are 12% and 37% greater than those of the PFH, respectively. Extended surface area and lighter weight may explain the better thermal performance of the HFH than the PFH.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.8 s.227
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• pp.961-967
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• 2004

An inclined jet impinging on a pin fin heat sink is proposed and investigated experimentally. To investigate the flow pattern, flow visualization using fluorescence and velocity measurement using particle image velocimetry(PIV) are conducted with water. The jet impinges over a wide span of the heat sink with a large recirculation in the upper free space and occasionally with another smaller one in the upstream corner. Further, thermal experimentation is conducted using air to obtain temperature profiles using a thermocouple rake in the air and using thermal image on the heat sink back plate, with impinging angles of 35, 45 and 55 degrees. The Reynolds number range based on the nozzle slot is varied from 1507 to 6405. The results show that impinging angle of 55 degree shows the largest heat transfer capability. The results of thermal experiment are compared and discussed with those of flow visualization.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.8
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• pp.667-673
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• 2003

Recent trends in the electronic equipment indicate that the power consumption and heat generation in a chip increase as the components are miniaturized and the computing speed becomes faster. Suitable heat dissipation is required to ensure the guaranteed performance and reliable operation of the electronic devices. The aim of the present study is to investigate the forced-convective thermal-hydraulic characteristics of a pin-fin heat exchanger as a candidate for cooling system of the electronic devices. The influence of the structure of the pin-fin assembly on heat transfer is investigated by porous medium model. The results are compared with the experimental data or correlations of several researchers for the heat transfer coefficients for the channel flow with pin-fin arrays. Finally, the effects of design parameters such as the pin-fin diameter and the spacing are examined.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.11
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• pp.1555-1563
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• 1998

Heat transfer and pressure drop for ${\phi}10.07$ dry surface fin-tube heat exchanger with wave and wave-slit fins were measured for different fin spacings and number of tube rows. Longitudinal and transverse tube spacings of the heat exchangers are 21.65mm and 25mm respectively, and wave depth of wave fin is 1.5mm. The experiments were performed for 4 different fin spacings, 1.3, 1.5, 1.7 and 2.0mm, and the number of tube rows were 1,2 and 3 rows. The present results were compared with the previous results for the wave depth of 2mm. Also hydrophilic coated and bare fins were tested. Correlations for Colburn j-factor and friction factor were developed.

• Journal of Institute of Convergence Technology
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• v.5 no.1
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• pp.27-31
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• 2015

A Pin-fin array is widely used to enhance the heat transfer in the internal cooling passage. The heat transfer distribution around the pin-fin is varied by the horseshoe vortex and flow separation. The difference of heat transfer coefficient induces the large thermal stress, which is one of the major reasons to break of hot components. So, it is required to enhance the heat transfer on the back side of pin-fin to solve the thermal stress problem. This study suggests the pin-fin with inclined jet hole and complex pin-fin/dimple array to enhance the heat transfer on the back side of pin-fin. The heat transfer coefficient is predicted by the numerical analysis, which is performed by CFX 14.0. The numerical results are obtained at Reynolds number, 10,000. The results show that the heat transfer on the back side of pin-fin is increased in both cases. Beside, the wake, which comes from dimple and jet, helps to develop the horseshoe vortex and increase the heat transfer on the next row pin-fin.