Numerical Investigation of Heat Transfer and Pressure Loss of Double-Layer Microchannels for Chip Liquid Cooling

2012 ◽  
Author(s):  
Gongnan Xie ◽  
Yanquan Liu ◽  
Bengt Sunden ◽  
Weihong Zhang ◽  
Jun Zhao
Keyword(s):  
Heat Transfer ◽  
Double Layer ◽  
Pressure Loss ◽  
Heat Dissipation ◽  
Thermal Characteristics ◽  
Parallel Flow ◽  
Air Cooling ◽  
Pumping Power ◽  
Liquid Cooling ◽  
Counter Flow

The problem involved in the increase of the chip output power of high-performance integrated electronic devices is the failure of reliability because of excessive thermal loads. This requires advanced cooling methods to manage the increase of the dissipated heat. The traditional air-cooling may not meet the requirements, and therefore a new generation of liquid cooling technology becomes necessary. Various microchannels are widely used to cool the electronic chips by a gas or liquid, but these microchannels are often designed to be single-layer channels. In this paper, the laminar heat transfer and pressure loss in a kind of double-layer microchannel have been investigated numerically. The layouts of parallel-flow and counter-flow for inlet/outlet flow directions are designed and then several sets of inlet flowrates are considered. The simulations show that such a double-layer microchannel can not only reduce the pressure drop effectively but also exhibits better thermal characteristics, and the parallel-flow layout is found to be better for heat dissipation when the pumping power is limited, while the counter-flow layout is better when a high pumping power is provided.

Computational Study and Optimization of Laminar Heat Transfer and Pressure Loss of Double-Layer Microchannels for Chip Liquid Cooling

2013 ◽  
Vol 5 (1) ◽  
Author(s):  
Gongnan Xie ◽  
Yanquan Liu ◽  
Bengt Sunden ◽  
Weihong Zhang
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Double Layer ◽  
Flow Rate ◽  
Single Layer ◽  
Parallel Flow ◽  
Heat Fluxes ◽  
Liquid Cooling ◽  
Counter Flow ◽  
Flow Rates

The problem involved in the increase of the chip output power of high-performance integrated electronic devices is the failure of reliability because of excessive thermal loads. This requires advanced cooling methods to be incorporated to manage the increase of the dissipated heat. The traditional air-cooling can not meet the requirements of cooling heat fluxes as high as 100 W/cm2, or even higher, and the traditional liquid cooling is not sufficient either in cooling very high heat fluxes although the pressure drop is small. Therefore, a new generation of liquid cooling technology becomes necessary. Various microchannels are widely used to cool the electronic chips by a gas or liquid removing the heat, but these microchannels are often designed to be single-layer channels with high pressure drop. In this paper, the laminar heat transfer and pressure loss of a kind of double-layer microchannel have been investigated numerically. The layouts of parallel-flow and counter-flow for inlet/outlet flow directions are designed and then several sets of inlet flow rates are considered. The simulations show that such a double-layer microchannel can not only reduce the pressure drop effectively but also exhibits better thermal characteristics. Due to the negative heat flux effect, the parallel-flow layout is found to be better for heat dissipation when the flow rate is limited to a low value while the counter-flow layout is better when a high flow rate can be provided. In addition, the thermal performance of the single-layer microchannel is between those of parallel-flow layout and counter-flow layout of the double-layer microchannel at low flow rates. At last, the optimizations of geometry parameters of double-layer microchannel are carried out through changing the height of the upper-branch and lower-branch channels to investigate the influence on the thermal performance.

Convective Heat Transfer of Parallel-Flow and Counter-Flow Double-Layer Microchannel Heat Sinks in Staggered Arrangement

2017 ◽  
Author(s):  
Han Shen ◽  
Yingchun Zhang ◽  
Hongbin Yan ◽  
Bengt Sunden ◽  
Gongnan Xie
Keyword(s):  
Heat Transfer ◽  
Double Layer ◽  
Electronic Devices ◽  
Structure Design ◽  
Parallel Flow ◽  
Heat Sinks ◽  
Counter Flow ◽  
Microchannel Heat Sinks ◽  
Staggered Arrangement ◽  
Flow Case

Previous research has proved Double-layer Microchannel Heat Sinks (MHSs) to be efficient ways to improve the cooling performance of electronic devices. However, the cooling potential of the upper working liquid cannot be fully utilized to cool down the substrate with the heated elements. In this sense, a concept of staggered double-layer MHS is proposed and designed. The parallel and counter flow directions are considered to investigate the flow arrangement effect. The Reynolds number effect, Nusselt number and pressure drop are analyzed in detail and compared with those of a parallel straight double-layer MHS. It is found that the staggered double-layer MHSs exhibit much better heat transfer enhancement and overall thermal performance compared with the parallel straight double-layer MHS. For the staggered double-layer MHSs, the counter flow case is superior to the parallel flow case. This research provides a new structure design to enhance the heat transfer in microchannel heat sinks and broad application prospects for heat sinks in the thermal management of high power density electronic devices.

scholarly journals Thermal Analysis of the Effects of Multifaceted Conditions on Performance of Shell-and-Tube Heat Exchanger

2021 ◽  
Vol 6 (1) ◽  
pp. 69-75
Author(s):  
Taiwo O. Oni ◽  
Ayotunde A. Ojo ◽  
Daniel C. Uguru-Okorie ◽  
David O. Akindele
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Parallel Flow ◽  
Hot Water ◽  
Inlet Temperature ◽  
Fiber Glass ◽  
Counter Flow ◽  
Tube Heat Exchanger ◽  
Shell And Tube ◽  
Flow Configurations

A shell-and-tube heat exchanger which was subjected to different flow configurations, viz. counter flow, and parallel flow, was investigated. Each of the flow configurations was operated under two different conditions of the shell, that is, an uninsulated shell and a shell insulated with fiber glass. The hot water inlet temperature of the tube was reduced gradually from 60 oC to 40 oC, and performance evaluation of the heat exchanger was carried out. It was found that for the uninsulated shell, the heat transfer effectiveness for hot water inlet temperature of 60, 55, 50, 45, and 40 oC are 0.243, 0.244, 0.240, 0.240, and 0.247, respectively, for the parallel flow arrangement. For the counter flow arrangement, the heat transfer effectiveness for the uninsulated shell are 2.40, 2.74, 5.00, 4.17, and 2.70%, respectively, higher than those for the parallel flow. The heat exchanger’s heat transfer effectiveness with fiber-glass-insulated shell for the parallel flow condition with tube hot water inlet temperatures of 60, 55, 50, 45, and 40 oC are 0.223, 0.226, 0.220, 0.225, and 0.227, respectively, whereas the counter flow condition has its heat transfer effectiveness increased by 1.28, 1.47, 1.82, 1.11, and 1.18%, respectively, over those of the parallel flow.

Flow and Heat Transfer Characteristics in Models of Turbine Blade Tip-Walls With Three Kinds of Turning Vanes

2018 ◽  
Author(s):  
Bin Wu ◽  
Xing Yang ◽  
Lv Ye ◽  
Zhao Liu ◽  
Yu Jiang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Turbine Blade ◽  
Double Layer ◽  
Pressure Loss ◽  
Stokes Equations ◽  
Wall Heat Transfer ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer ◽  
Blade Tip

In this paper, effects of three kinds of turning vanes on flow and heat transfer of turbine blade tip-walls with a U-shaped channel have been numerically studied. Numerical simulations are performed to solve three-dimensional, steady, Reynolds-averaged Navier-Stokes equations with the standard k-ω turbulence model. The aspect ratio (AR) and the hydraulic diameter of the channel are 2 and 93.13 mm, respectively. The effects of single-layer, double-layer and double-layer dome-shaped turning vanes in the turn region on the tip-wall heat transfer and overall pressure loss of rectangular U-shaped channels are analyzed. Detailed flow and heat transfer characteristics over the tip-walls, as well as the overall performance, are presented and compared with each other. Results show that the tip-wall heat transfer coefficients with double-layer dome-shaped turning vanes are the highest among the three cases. Double-layer dome-shaped turning vanes can promote the lateral spreading of secondary flow and effectively increase the uniformity of heat transfer on the tip-wall. More importantly, this structure can make the cooling air expand and accelerate at the center region of the top of the U-shaped channel, resulting in more heat to be removed from the tip-wall. Additionally, double-layer dome-shaped turning vanes can effectively reduce the pressure loss of the channel.

Fin Analysis Under Transition Boiling Heat Transfer: Part II — Radial Fins

2002 ◽  
Author(s):  
Rizos N. Krikkis ◽  
Stratis V. Sotirchos ◽  
Panagiotis Razelos
Keyword(s):  
Heat Transfer ◽  
Power Law ◽  
Biot Number ◽  
Boiling Heat Transfer ◽  
Heat Dissipation ◽  
Thermal Characteristics ◽  
Radius Ratio ◽  
Operating Variables ◽  
Simplifying Assumptions ◽  
Saturated Boiling

The thermal characteristics of six profiles of radial fins subject to transition boiling heat transfer are analyzed. The profiles considered are the rectangular the trapezoidal, the triangular, the convex parabolic, the parabolic and the hyperbolic. The model of the physical mechanism is based on one-dimensional heat conduction using certain simplifying assumptions while the heat transfer coefficient is modeled as a power-law function of the temperature difference between the fin and the saturated boiling liquid with a negative exponent. The problem is formulated by means of dimensionless variables and parameters such as the conduction-convection parameter, the radius ratio and the Biot number that characterize the problem. The multiplicity structure is obtained in order to determine the different types of bifurcation diagrams, which describe the dependence of a state variable of the system (for instance the fin temperature or the heat dissipation) on a design (CCP, radius ratio) or operation parameter (power-law exponent). Specifically the effects of the radius ratio, of the CCP and of the Biot number are analyzed and presented in several diagrams since it is important to know the behavioral features of the heat rejection mechanism such as the number of the possible steady states and the influence of a change in one or more operating variables to these states.

Thermal Performance Maps for Forced Air Cooling of Ruggedized Electronics Enclosures

2007 ◽  
Author(s):  
Jesse VanEngelenhoven ◽  
Gary L. Solbrekken ◽  
Karl J. L. Geisler
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Dissipation ◽  
Side Wall ◽  
Form Factors ◽  
Air Cooling ◽  
Heat Transfer Capacity ◽  
Flow Pressure ◽  
Forced Air ◽  
Analytic Models

Based on standard commercial form factors, this study explores chassis-level air cooling limits for ruggedized military electronics enclosures constrained by pressure drop requirements and fin manufacturing capabilities. Numeric and analytic models are developed and used to define a methodology for optimizing the geometry of longitudinal plate fins included in side wall ducts to maximize the amount of heat that can be dissipated from an air-cooled chassis. The results of these analyses are presented in the form of a performance map facilitate the identification of particular fin manufacturing process well-suited for a specified set of mass flow, pressure drop, and heat transfer requirements. Analysis results demonstrate that if isothermal boundaries can be achieved, the heat transfer capacity of the chassis will increase relative to isoflux boundary condition assumptions. As a means to this end, the incorporation of heat pipes into the chassis wall is explored to enhance heat spreading and approach the isothermal limits of heat dissipation in the airflow ducts.

Visualization of FC-72 Flow Boiling in Parallel- and Counter-Flow Plate Heat Exchangers

2014 ◽  
Author(s):  
Kohei Koyama ◽  
Yuya Nakamura ◽  
Hirofumi Arima
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Flow Pattern ◽  
Void Fraction ◽  
Flow Boiling ◽  
Plate Heat Exchanger ◽  
Parallel Flow ◽  
Working Fluid ◽  
Counter Flow ◽  
Plate Heat

This study investigates FC-72 (Perfluorohexane) flow boiling in a plate heat exchanger. A plate heat exchanger which has a transparent cover plate is manufactured to visualize boiling two-phase flow pattern of the working fluid FC-72 heated by hot water. Titanium is used for heat transfer plate, which has micro pin-fin structure on the heat transfer surface to enhance heat transfer. Experiment is conducted for parallel- and counter-flow arrangements to compare thermal and hydraulic performances. Flow boiling is photographed by a digital camera and instantaneous images are processed to classify flow pattern and to measure void fraction in the heat exchanger. Flow rates and temperatures of FC-72 and hot water at inlet and outlet of the heat exchanger are simultaneously measured to obtain overall heat transfer coefficient. Two-phase flow pattern of FC-72 flow boiling and void fraction along flow direction as well as thermal performance are discussed. Experimental results show that bubbly flow, slug flow, and churn flow are observed for the experimental range of this study. Extent of churn flow in the parallel-flow heat exchanger is larger than that of the counter-flow one due to generated bubbles at upstream region in working fluid channel. Void fraction of the parallel-flow plate heat exchanger increases rapidly compared with that of the counter-flow one due to location of onset of nucleate boiling. Overall heat transfer coefficients for the parallel-flow arrangement is larger than that of the counter-flow due to destruction of thermal boundary layer. The experimental results show that flow arrangement of a plate heat exchanger has the potential to improve its thermal performance.

Cooling Performances of Perforated-Finned Heat Sinks

2016 ◽  
Author(s):  
Mohammad Reza Shaeri ◽  
Bradley Richard ◽  
Richard Bonner
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Heat Sink ◽  
Cooling System ◽  
Thermal Characteristics ◽  
Heat Sinks ◽  
Pumping Power ◽  
Maximum Heat ◽  
Maximum Heat Transfer

Cooling performances of perforated-finned heat sinks (PFHS) are investigated in the laminar forced convection heat transfer mode, through detailed experiments. Perforations like windows with square cross sections are placed on the lateral surfaces of the fins. Cooling performances are evaluated due to changes in both porosities and perforation sizes. Thermal characteristics are reported based on pumping power, in order to provide more practical insight about performances of PFHSs in real applications. It is found that at a constant perforation size, there is an optimum porosity that results in the largest heat transfer coefficient. For a fixed porosity, increasing the number of perforations (reducing the perforation size) results in an enhancement of heat transfer rate due to repeated interruption of the thermal boundary layer. The opposite trend is observed for PFHSs with larger perforation sizes. This indicates that there is an optimum perforation size and distance between perforations in order to achieve the maximum heat transfer coefficients at a constant porosity. Also, a PFHS results in a smaller temperature non-uniformity across the heat sink base, as well as a more rapid reduction in temperature non-uniformity on the heat sink base by increasing pumping power. In addition, the advantage of a PFHS to reduce the overall weight of the cooling system is incorporated into thermal characteristics of the heat sinks, and demonstrated by the mass specific heat transfer coefficient.

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