International Journal of Heat and Mass Transfer, 2015
ABSTRACT Enhanced microchannel heat sink with sectional oblique fin is used to modulate the flow ... more ABSTRACT Enhanced microchannel heat sink with sectional oblique fin is used to modulate the flow in contrast to continuous straight fin. The re-initialization of thermal boundary layer at the leading edge of each oblique due to breakage of continuous fin into oblique sections and the secondary flow due to these oblique cuts resulted in better heat transfer and a comparable pressure drop. Extensive experimental investigations are carried out with silicon test vehicle with hydraulic diameter of 100 μm and 200 μm and de-ionized water as flowing fluid. A parametric study involving the oblique angle, fin pitch is also carried out. Appreciable heat transfer augmentation is also achieved with maximum heat transfer performance enhancement at 47% when Re = 680. Comparable pressure drop to conventional microchannel is maintained up to Re = 500. Parametric study suggests that smaller oblique angle and smaller fin pitch are beneficial for heat transfer enhancement. The performance of the microchannel with 100 μm channel width and 27° oblique angle is found to be optimum.
Volume 2: Thermal Management; Data Centers and Energy Efficient Electronic Systems, 2013
ABSTRACT A novel cylindrical oblique fin minichannel heat sink was proposed to cool cylindrical h... more ABSTRACT A novel cylindrical oblique fin minichannel heat sink was proposed to cool cylindrical heat sources using forced convection scheme. In this paper, parametric numerical study was employed to understand the importance of the various dimensions of the oblique fin heat sinks and their heat transfer performance and pressure drop. Three dimensional conjugated heat transfer simulations were carried out using Computational Fluid Dynamics (CFD) method based on laminar flow to determine its performance in the oblique fin heat sink. 214 parametric studies were performed by varying the oblique angle from 20° to 45°, secondary channel gap from 1mm to 5mm and Reynolds number from 200 to 900. Their thermal performance was compared for a constant heat flux of 1 W/cm2. The results show that the flow is main channel directed in shorter secondary channel structure while the flow becomes secondary channel directed in longer secondary channel structure. Secondary flow becomes more effective in heat transfer when increasing the secondary channel gap. When the oblique angle increases, more flow will be diverted into secondary channel and improve flow mixing to enhance the heat transfer. The best configuration in this paper was suggested based on the numerical data point. The overall performance can be improved up to 110% at Reynolds number of 900 compared with conventional straight fin minichannel. Therefore, this is the attractive candidate for future cylindrical heat sinks.
ITherm 2002. Eighth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (Cat. No.02CH37258), 2002
... Poh Seng Lee, Juay Choy Ho Department of Mechanical Engineering National University of Singap... more ... Poh Seng Lee, Juay Choy Ho Department of Mechanical Engineering National University of Singapore 10 ... ApeXp = PUI'K, where K, = Resistance of sudden expansion &.lam = 1.66(Ai/A2)* - 2.66 ... The power supplied to the heater strips is detesmined using Ohm's law and this is ...
American Society of Mechanical Engineers, Heat Transfer Division, (Publication) HTD, 2005
Hot-Spot Thermal Management With Flow Modulation in a Microchannel Heat Sink. [ASME Conference Pr... more Hot-Spot Thermal Management With Flow Modulation in a Microchannel Heat Sink. [ASME Conference Proceedings 2005, 643 (2005)]. Poh-Seng Lee, Suresh V. Garimella. Abstract. Recesses created in the lid of a microchannel ...
2008 Proceedings of the ASME Micro/Nanoscale Heat Transfer International Conference, MNHT 2008, 2008
The ever-increasing density, speed, and power consumption of microelectronics has led to a rapid ... more The ever-increasing density, speed, and power consumption of microelectronics has led to a rapid increase in the heat fluxes which need to be dissipated in order to ensure their stable and reliable operation. The shrinking dimensions of electronics devices, in parallel, have ...
Proceedings of the ASME Summer Heat Transfer Conference 2009, HT2009, 2009
ABSTRACT In this paper, we have designed a compact and efficient liquid-cooled heat sink for mini... more ABSTRACT In this paper, we have designed a compact and efficient liquid-cooled heat sink for mini-sized electronic devices, particularly for very-large-scale integrated (VLSI) circuits. The heat sink can either be an integral part of the silicon (or metal) substrate, or a separate part attached onto the substrate. The heat sink consists of several wavy microchannels, with hydraulic diameter on the order of 100 μm, microfabricated on a silicon or metal substrate. The fluid flow and heat transfer performance of the heat sink are studied using numerical simulations in the steady laminar flow region and the dynamical system technique using Poincaré sections is employed to analyze the fluid mixing. It is found that when the liquid coolant flows through the wavy microchannel, Dean vortices can develop. The quantity and location of the Dean vortices may change along the flow direction, which can lead to laminar chaos. The chaotic advection greatly enhances the fluid mixing, and thus the heat transfer performance of the present heat sink is much more superior than previous designs which employed straight microchannels. It is also found that the pressure drop penalty is much smaller that the heat transfer enhancement for the present heat sink. Furthermore, the relative wavy amplitude (wavy amplitude/wavelength) of the channels can be varied along the flow direction for various purposes, without compromising the compactness and efficiency of the heat sink. The relative waviness can be increased along the flow direction, which results in higher heat transfer coefficients and renders the temperature for the devices much more uniform. The relative waviness can also be designed to be higher in regions of high heat flux for hot spot mitigation purposes.
International Journal of Heat and Mass Transfer, 2015
ABSTRACT Enhanced microchannel heat sink with sectional oblique fin is used to modulate the flow ... more ABSTRACT Enhanced microchannel heat sink with sectional oblique fin is used to modulate the flow in contrast to continuous straight fin. The re-initialization of thermal boundary layer at the leading edge of each oblique due to breakage of continuous fin into oblique sections and the secondary flow due to these oblique cuts resulted in better heat transfer and a comparable pressure drop. Extensive experimental investigations are carried out with silicon test vehicle with hydraulic diameter of 100 μm and 200 μm and de-ionized water as flowing fluid. A parametric study involving the oblique angle, fin pitch is also carried out. Appreciable heat transfer augmentation is also achieved with maximum heat transfer performance enhancement at 47% when Re = 680. Comparable pressure drop to conventional microchannel is maintained up to Re = 500. Parametric study suggests that smaller oblique angle and smaller fin pitch are beneficial for heat transfer enhancement. The performance of the microchannel with 100 μm channel width and 27° oblique angle is found to be optimum.
Volume 2: Thermal Management; Data Centers and Energy Efficient Electronic Systems, 2013
ABSTRACT A novel cylindrical oblique fin minichannel heat sink was proposed to cool cylindrical h... more ABSTRACT A novel cylindrical oblique fin minichannel heat sink was proposed to cool cylindrical heat sources using forced convection scheme. In this paper, parametric numerical study was employed to understand the importance of the various dimensions of the oblique fin heat sinks and their heat transfer performance and pressure drop. Three dimensional conjugated heat transfer simulations were carried out using Computational Fluid Dynamics (CFD) method based on laminar flow to determine its performance in the oblique fin heat sink. 214 parametric studies were performed by varying the oblique angle from 20° to 45°, secondary channel gap from 1mm to 5mm and Reynolds number from 200 to 900. Their thermal performance was compared for a constant heat flux of 1 W/cm2. The results show that the flow is main channel directed in shorter secondary channel structure while the flow becomes secondary channel directed in longer secondary channel structure. Secondary flow becomes more effective in heat transfer when increasing the secondary channel gap. When the oblique angle increases, more flow will be diverted into secondary channel and improve flow mixing to enhance the heat transfer. The best configuration in this paper was suggested based on the numerical data point. The overall performance can be improved up to 110% at Reynolds number of 900 compared with conventional straight fin minichannel. Therefore, this is the attractive candidate for future cylindrical heat sinks.
ITherm 2002. Eighth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (Cat. No.02CH37258), 2002
... Poh Seng Lee, Juay Choy Ho Department of Mechanical Engineering National University of Singap... more ... Poh Seng Lee, Juay Choy Ho Department of Mechanical Engineering National University of Singapore 10 ... ApeXp = PUI'K, where K, = Resistance of sudden expansion &.lam = 1.66(Ai/A2)* - 2.66 ... The power supplied to the heater strips is detesmined using Ohm's law and this is ...
American Society of Mechanical Engineers, Heat Transfer Division, (Publication) HTD, 2005
Hot-Spot Thermal Management With Flow Modulation in a Microchannel Heat Sink. [ASME Conference Pr... more Hot-Spot Thermal Management With Flow Modulation in a Microchannel Heat Sink. [ASME Conference Proceedings 2005, 643 (2005)]. Poh-Seng Lee, Suresh V. Garimella. Abstract. Recesses created in the lid of a microchannel ...
2008 Proceedings of the ASME Micro/Nanoscale Heat Transfer International Conference, MNHT 2008, 2008
The ever-increasing density, speed, and power consumption of microelectronics has led to a rapid ... more The ever-increasing density, speed, and power consumption of microelectronics has led to a rapid increase in the heat fluxes which need to be dissipated in order to ensure their stable and reliable operation. The shrinking dimensions of electronics devices, in parallel, have ...
Proceedings of the ASME Summer Heat Transfer Conference 2009, HT2009, 2009
ABSTRACT In this paper, we have designed a compact and efficient liquid-cooled heat sink for mini... more ABSTRACT In this paper, we have designed a compact and efficient liquid-cooled heat sink for mini-sized electronic devices, particularly for very-large-scale integrated (VLSI) circuits. The heat sink can either be an integral part of the silicon (or metal) substrate, or a separate part attached onto the substrate. The heat sink consists of several wavy microchannels, with hydraulic diameter on the order of 100 μm, microfabricated on a silicon or metal substrate. The fluid flow and heat transfer performance of the heat sink are studied using numerical simulations in the steady laminar flow region and the dynamical system technique using Poincaré sections is employed to analyze the fluid mixing. It is found that when the liquid coolant flows through the wavy microchannel, Dean vortices can develop. The quantity and location of the Dean vortices may change along the flow direction, which can lead to laminar chaos. The chaotic advection greatly enhances the fluid mixing, and thus the heat transfer performance of the present heat sink is much more superior than previous designs which employed straight microchannels. It is also found that the pressure drop penalty is much smaller that the heat transfer enhancement for the present heat sink. Furthermore, the relative wavy amplitude (wavy amplitude/wavelength) of the channels can be varied along the flow direction for various purposes, without compromising the compactness and efficiency of the heat sink. The relative waviness can be increased along the flow direction, which results in higher heat transfer coefficients and renders the temperature for the devices much more uniform. The relative waviness can also be designed to be higher in regions of high heat flux for hot spot mitigation purposes.
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