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.

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.

Passive Heat Transfer Enhancement in Microchannels Using Wall Features

2007 ◽  
Author(s):  
Ravi Arora ◽  
Anna Lee Tonkovich ◽  
Mike J. Lamont ◽  
Thomas Yuschak ◽  
Laura Silva
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Pressure Drop ◽  
Heat Transfer Enhancement ◽  
Heat Transfer Rate ◽  
Flow Rate ◽  
Transfer Rate ◽  
Transfer Enhancement ◽  
Flow Rates ◽  
Feature Design

The two important considerations in the design of a heat exchanger are — the total heat transfer rate and the allowable pressure drop. The allowable pressure drop defines the maximum flow rate through a single microchannel and economics drives the design towards this flow rate. Typically the flow rate in the microchannel is in laminar flow regime (Re < 2000) due to smaller hydraulic diameter. The laminar flow heat transfer in a smooth microchannel is limited by the boundary layer thickness. Commonly the heat transfer rate is enhanced by passively disrupting the laminar boundary layer using protrusions or depressions in the channel walls. More often these methods are best applicable at small range of Reynolds number where the heat transfer rate enhancement is more than the pressure drop increase and break down as the flow rate is changed outside the range. The benefit of a flow disruption method can be reaped only if it provides higher heat transfer enhancement than the increase in the pressure drop at the working flow rates in the microchannel. A heat transfer efficient microchannel design has been developed using wall features that create stable disrupted flow and break the laminar boundary layer in a microchannel over a wide range of flow rates. The paper experimentally investigates the developed design for the heat transfer enhancement and pressure drop increase compared to a smooth wall microchannel. A simple microchannel device was designed and fabricated with and without wall features. The experiments with single gas phase fluid showed promising results with the developed wall feature design as the heat transfer rate increase was 20% to 80% more than the pressure drop increase in the laminar regime. The wall feature design was an important variable to affect the magnitude of performance enhancement in different flow regime. A general criterion was developed to judge the efficacy of wall feature design that can be used during a microchannel heat exchanger design.

Channel Size Optimization for 3D-IC Integrated Interlayer Microchannel Liquid Cooling

2016 ◽  
Author(s):  
D. D. Ma ◽  
G. D. Xia ◽  
W. Wang ◽  
X. F. Li ◽  
Y. T. Jia
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Rectangular Channel ◽  
Channel Structure ◽  
Maximum Temperature ◽  
Liquid Cooling ◽  
3D Ic ◽  
Flow Rates ◽  
Multi Objective ◽  
Contraction Ratio

3D-IC is getting increasingly attractive, as it improves speed and frequency, and reduces power consumption, noise and latency. However, three dimension (3D) integration technologies bring a new serious challenge to chip thermal management with the power density increased exponentially. Interlayer microchannel liquid cooling is thought as a promising and scalable solution for cooling high heat flux 3D-IC. In this paper, firstly channel number, channel width and height parameters of rectangular channel are optimized by the method of multi-objective parameter optimization under given overall size of 5mm in length and 5mm in width. The results show the total thermal resistances can reach very small under individual constraint condition of volume flow rates, but the pressure drop is too larger to accept. The minimum thermal resistance structure can be got by multi-objective optimization at various constraint conditions. It is found that the channel height and width increase with increasing of flow rates at pumping power less than 0.1W and pressure drop less than 20kPa. Secondly, the zigzag channels are designed on the basis of the optimized rectangular channel structure. The expansion and contraction ratio as an important parameter is optimized by numerical simulation. The thermal enhancement factor and Nusselt number measure the comprehensive performances of heat transfer. The results show heat transfer characteristic is enhanced with the decreasing of expansion and contraction ratio. Besides, the maximum junction temperature and maximum temperature difference are also reduced. 3D-IC with wave channel of β=3/7 is more promising for interlayer cooling.

Experimental Study on Two-Phase Heat Transfer of FC-72 in Microchannels Heat Sink

2009 ◽  
Author(s):  
Xiao Hu ◽  
Guiping Lin ◽  
Hongxing Zhang
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Pressure Drop ◽  
Flow Rate ◽  
Mass Flux ◽  
Heat Sink ◽  
Heat Fluxes ◽  
High Mass ◽  
Two Phase ◽  
Two Phase Heat Transfer

A closed-loop two-phase microchannels cooling system using a micro-gear pump was built in this paper. The microchannels heat sink was made of oxygen-free copper, and 14 parallel microchannels with the dimension of 0.8mm(W)×1.5mm(D)×20mm(L) were formed by electric spark drilling followed by linear cutting which separated the channels from each other. The heat transfer performance was evaluated by the fluid temperature, the pressure drop across the micro-channels and the volumetric flow rate. Experiments were performed with refrigerant FC-72 which spanned the following conditions: initial pressure of Pin = 73 kPa, mass velocity of G = 94 – 333 kg/m2s, outlet quality of xe,out = 0 – superheat and heat flux of q″= 25–140 W/cm2. The result showed that, the maximum heat flux achieved 96 W/cm2, as the heating surface temperature was kept below 85 °C and critical heat flux occurred in the condition of low flow rate. Average two-phase heat transfer coefficients increased with the heat flux at low mass flux (G = 94 and 180 kg/m2s) and all heat fluxes, high mass flux (G = 333 kg/m2s) and all heat fluxes, and moderate mass fluxes (G = 224kg/m2s) under low and moderate heat fluxes (q″&lt;110 W/cm2 for G = 224 kg/m2s), which was a feature of nucleate boiling mechanism. Pressure drop through microchannels heat sink was found to be below 4kPa.

scholarly journals Experimental investigation on heat transfer and pressure drop of conical coil heat exchanger

2016 ◽  
Vol 20 (6) ◽  
pp. 2087-2099 ◽  
Author(s):  
Pramod Purandare ◽  
Mandar Lele ◽  
Raj Gupta
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Flow Rate ◽  
Cone Angle ◽  
Tube Diameter ◽  
Flow Rates ◽  
Side Flow ◽  
Coil Heat

The heat transfer and pressure drop analysis of conical coil heat exchanger with various tube diameters, fluid flow rates, and cone angles is presented in this paper. Fifteen coils of cone angles 180? (horizontal spiral), 135?, 90?, 45?, and 0? (vertical helical) are fabricated and analysed with, same average coil diameter, and tube length, with three different tube diameters. The experimentation is carried out with hot and cold water of flow rate 10 to 100 L per hour (Reynolds range 500 to 5000), and 30 to 90 L per hour, respectively. The temperatures and pressure drop across the heat exchanger are recorded at different mass flow rates of cold and hot fluid. The various parameters: heat transfer coefficient, Nusselt number, effectiveness, and friction factor, are estimated using the temperature, mass flow rate, and pressure drop across the heat exchanger. The analysis indicates that, Nusselt number and friction factor are function of flow rate, tube diameter, cone angle, and curvature ratio. Increase in tube side flow rate increases Nusselt number, whereas it reduces with increase in shell side flow rate. Increase in cone angle and tube diameter, reduces Nusselt number. The effects of cone angle, tube diameter, and fluid flow rates on heat transfer and pressure drop characteristics are detailed in this paper. The empirical correlations are proposed to bring out the physics of the thermal aspects of the conical coil heat exchangers.

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 Application of a Double Layer Circular Microchannel Heat Sink in Electronic Industry

2019 ◽  
Vol 8 (12) ◽  
pp. 1153-1158
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Heat Sink ◽  
Microchannel Heat Sink ◽  
Temperature Uniformity ◽  
Counter Flow ◽  
Circular Microchannel

The present paper is focused to evaluate the pressure drop and heat transfer performance of a double layer circular microchannel heat sink with numerically and experimentally. Numerical analysis is carried for various mass flow rates, with turbulent condition used in the ANSYS Fluent for two flow arrangements. The experiment is carried out by varying the mass flow rate ranges 3.32x10-4 kg/s to 27.72x10-4 kg/s with water as the cooling medium. The effect of a parallel flow and counter flow arrangements on heat transfer and flow parameters is studied for a constant heat input of 80W. The numerical result is nearly the same with the measured values. The pressure drop increases with the mass flow rate. The heat transfer enhancement is evaluated by the wall surface temperature and temperature uniformity. Even though parallel and counter flow arrangement has similar flow and thermal behavior, the latter has better temperature uniformity in the base of the heat sink for all pumping powers.

Thermal Performance Comparison for Five Liquid Heat Sink Designs

2011 ◽  
Author(s):  
Christopher Greene ◽  
Randall D. Manteufel ◽  
Amir Karimi
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Thermal Resistance ◽  
Flow Rate ◽  
Heat Sink ◽  
Fluid Velocity ◽  
Water Flow Rate ◽  
High Flow ◽  
Heat Transfer Area ◽  
Flow Rates

Five high-flow liquid-cooled heat sink designs are compared for the cooling of a single chip CPU. Five distinctive design configurations are considered with regard to the introduction, passage, and extraction of cooling fluid. The typical water flow rate is about 3.8 liters per minute (lpm) with flow passages in the primary heat transfer area ranging from 2 to 0.1mm. The design configurations are summarized and compared, considering: the primary convective heat transfer area, flow passage streamlining, acceleration mechanisms, and nominal fluid velocity in the primary heat transfer area. Overall pressure drop and thermal resistance are compared for varying flow rates of water. At the nominal flow, the pressure drops ranged from 1 kPa to 20 kPa. In the restrictive designs, such as nozzles, flow acceleration accounts for the largest source of pressure drop. In some designs, a large fraction of the overall pressure drop is due to circuitous flow associated with the introduction and/or extraction of flow which contributes little to heat removal. At the nominal flow, the overall thermal resistance varied from 0.14 to 0.18 C/W. As flow rate increases the overall thermal resistance decreases. Results indicated that 80 to 85% of the total thermal resistance is due to conduction and about 15 to 20% attributed to convection at the nominal flow rate. There is minimal thermal benefit for flow rates beyond twice the nominal while this substantially increases fluid pumping requirements. This study highlights design features which yield above average heat transfer performance with minimal pressure drop for high-flow liquid-cooled heat sinks.

Simultaneous Measuring Method for Both Volumetric Flow Rates of Air-Water Mixture Using a Turbine Flowmeter

1996 ◽  
Vol 118 (1) ◽  
pp. 29-35 ◽  
Author(s):  
K. Minemura ◽  
K. Egashira ◽  
K. Ihara ◽  
H. Furuta ◽  
K. Yamamoto
Keyword(s):  
Pressure Drop ◽  
Flow Rate ◽  
Volumetric Flow Rate ◽  
Oil Field ◽  
Liquid Density ◽  
Water Mixture ◽  
Rotor Speed ◽  
Flow Rates ◽  
Field Development ◽  
Turbine Flowmeter

A turbine flowmeter is employed in this study in connection with offshore oil field development, in order to measure simultaneously both the volumetric flow rates of air-water two-phase mixture. Though a conventional turbine flowmeter is generally used to measure the single-phase volumetric flow rate by obtaining the rotational rotor speed, the method proposed additionally reads the pressure drop across the meter. After the pressure drop and rotor speed measured are correlated as functions of the volumetric flow ratio of the air to the whole fluid and the total volumetric flow rate, both the flow rates are iteratively evaluated with the functions on the premise that the liquid density is known. The evaluated flow rates are confirmed to have adequate accuracy, and thus the applicability of the method to oil fields.

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