Thermal and Manufacturing Design Considerations for Silicon-Based Embedded Microchannel-Three-Dimensional Manifold Coolers—Part 2: Parametric Study of EMMCs for High Heat Flux (∼1 kW/cm2) Power Electronics Cooling

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Ki Wook Jung ◽  
Sougata Hazra ◽  
Heungdong Kwon ◽  
Alisha Piazza ◽  
Edward Jih ◽  
...  
Keyword(s):  
Heat Flux ◽  
Pressure Drop ◽  
Power Electronics ◽  
Parametric Study ◽  
Three Dimensional ◽  
Working Fluid ◽  
Inlet Temperature ◽  
High Heat Flux ◽  
Dimensional Manifold ◽  
Power Capability

Abstract Thermal management of power electronics modules is one of the limiting factors in the peak power capability of the traction inverter system and overall efficiency of the e-drive. Liquid cooling using embedded microchannels with a three-dimensional (3D)-manifold cooler (EMMC) is a promising technology capable of removing heat fluxes of >1 kW/cm2 at tens of kPa pressure drop. In this work, we utilize computational fluid dynamics (CFD) simulations to conduct a parametric study of selected EMMC designs to improve the thermofluidic performance for a 5 mm × 5 mm heated area with the applied heat flux of 800 W/cm2 using single-phase water as working fluid at inlet temperature of 25 °C. We implemented strategies such as: (i) symmetric distribution of manifold inlet/outlet conduits, (ii) reducing the thickness of cold-plate (CP) substrate, and (iii) increasing fluid–solid interfacial area in CP microchannels, which resulted in a reduction in thermal resistance from 0.1 for baseline design to 0.04 cm2 K/W, while the pressure drop increased from 8 to 37 kPa.

Parametric Study of Silicon-Based Embedded Microchannels With 3D Manifold Coolers (EMMC) for High Heat Flux (~1 kW/cm2) Power Electronics Cooling

2019 ◽  
Author(s):  
Ki Wook Jung ◽  
Sougata Hazra ◽  
Heungdong Kwon ◽  
Alisha Piazza ◽  
Edward Jih ◽  
...  
Keyword(s):  
Heat Flux ◽  
Power Electronics ◽  
Parametric Study ◽  
Peak Power ◽  
Peak Power Output ◽  
Working Fluid ◽  
Inlet Temperature ◽  
High Heat Flux ◽  
Cold Plate ◽  
Power Capability

Abstract Thermal management of power electronics continues to be one of the limiting factors in the peak power capability of the traction inverter system and overall efficiency of the e-drive. Successful design and implementation of Embedded Microchannels with a 3D-Manifold Cooler, or EMMC, could enable higher power density that allows increase in the inverter peak power output. In the present work, we have conducted a parametric study on geometric dimensions of the EMMCs to analyze thermofluidic performance by using computational fluid dynamics (CFD) simulations. The study was conducted for a 5 mm × 5 mm cold-plate foot print, heat flux 800 W/cm2, and single-phase water as working fluid at inlet temperature of 25 °C. We implemented strategies such as i) symmetric distribution of manifold inlet/outlet conduits, ii) reducing the thickness of cold-plate substrate, iii) increasing fluid-solid interfacial area in cold-plate microchannels that resulted in reduction in thermal resistance of the baseline EMMC design from 0.1 to 0.04 cm2-K/W with pressure drop from 8 to 37 kPa.

Effects of Taper Configurations on Heat Transfer and Pressure Drop in Single-Phase Flows in Microgaps

2020 ◽  
Author(s):  
Debora C. Moreira ◽  
Gherhardt Ribatski ◽  
Satish G. Kandlikar
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Pressure Drop ◽  
Single Phase ◽  
Bubble Nucleation ◽  
Low Flow ◽  
Working Fluid ◽  
Inlet Temperature ◽  
Inlet Section ◽  
Flow Rates

Abstract This paper presents a comparison of heat transfer and pressure drop during single-phase flows inside diverging, converging, and uniform microgaps using distilled water as the working fluid. The microgaps were created on a plain heated copper surface with a polysulfone cover that was either uniform or tapered with an angle of 3.4°. The average gap height was 400 microns and the length and width dimensions were 10 mm × 10 mm, resulting in an average hydraulic diameter of approximately 800 microns for all configurations. Experiments were conducted at atmospheric pressure and the inlet temperature was set to 30 °C. Heat transfer and pressure drop data were acquired for flow rates varying from 57 to 485 ml/min and the surface temperature was monitored not to exceed 90 °C to avoid bubble nucleation, so the heat flux varied from 35 to 153 W/cm2 depending on the flow rate. The uniform configuration resulted in the lowest pressure drop, and the diverging one showed slightly higher pressure drop values than the converging configuration, possibly because the flow is most constrained at the inlet section, where the fluid is colder and presents higher viscosity. In addition, a minor dependence of pressure drop with heat flux was observed due to temperature dependent properties. The best heat transfer performance was obtained with the converging configuration, which was especially significant at low flow rates. This behavior could be explained by an increase in the heat transfer coefficient due to flow acceleration in converging gaps, which compensates the decrease in temperature difference between the fluid and the surface due to fluid heating along the gap. Overall, the comparison between the three configurations shows that converging microgaps have better performance than uniform or diverging ones for single-phase flows, and such effect is more pronounced at lower flow rates, when the fluid experiences higher temperature changes.

Enhanced Flow Boiling of Ethanol in Open Microchannels With Tapered Manifolds in a Gravity-Driven Flow

2015 ◽  
Author(s):  
Philipp K. Buchling ◽  
Satish G. Kandlikar
Keyword(s):  
Heat Flux ◽  
Pressure Drop ◽  
Flow Boiling ◽  
Low Pressure ◽  
High Heat ◽  
Working Fluid ◽  
High Heat Flux ◽  
Surface Geometry ◽  
Gravity Driven ◽  
Gravity Driven Flow

Flow boiling in microchannel heat sinks has been studied extensively in the past decade with the aim of implementation in the cooling of high-power integrated circuit chips. It has the potential to provide high-heat flux cooling at low wall superheats and a compact heater surface geometry. Prior works using water as the working fluid have shown that open microchannels with tapered manifolds deliver enhanced flow boiling performance, with substantial improvements in flow stability and a low pressure drop. The present work investigates the use of ethanol in flow boiling via a gravity-driven flow loop, eliminating the need for a pump. The flow boiling performance, critical heat flux (CHF) behavior, and pressure drop characteristics of ethanol in open microchannels with tapered gap manifolds (OMM) are studied. Several microchannel chips with different manifold gap heights and channel geometries are tested at multiple flow rates. The performance of ethanol in the present work was found to exceed all previously published results with ethanol, with a record maximum heat flux of 217 W/cm2 at a wall superheat of 34°C. Thanks to a remarkably low pressure drop, with maximal values below 9 kPa, ethanol is identified as a suitable dielectric fluid for reaching high heat flux goals in a gravity-driven configuration investigated in this study.

Critical Heat Flux (CHF) and Cold-Flow Pressure Drop Investigations of R-11 in a Vertical Uniformly Heated 5 x 5 Rod Bundle

2005 ◽  
Author(s):  
Asif Salahudidin ◽  
Jamil A. Khan ◽  
L. David Smith ◽  
Chris L. Wilbur
Keyword(s):  
Heat Flux ◽  
South Carolina ◽  
Pressure Drop ◽  
Critical Heat Flux ◽  
Mass Flux ◽  
Working Fluid ◽  
Inlet Temperature ◽  
Cold Flow ◽  
Rod Bundle ◽  
Flow Pressure

Experimental and numerical investigations were performed to determine the critical heat flux (CHF) and pressure drop in a vertical uniformly heated 5×5 rod bundle. R-11 is used as the working fluid due to its low latent heat, low critical pressure and well known properties. The experimental investigation was performed at the Westinghouse Nuclear Fuel PWR Product Technologies Test Laboratory in Columbia, South Carolina. Two types of grid designs were tested with Bundle-1 and Bundle-2 respectively. The matrix of DNB test parameters (water equivalent conditions shown in parentheses) includes exit pressure: 317–445 psia (1800–2400), inlet mass flux: 1.725–3.400 Mlbm/hr-ft2 (1.5–2.5 Mlbm/hr-ft2) and inlet temperature: 170–305°F (320–590 Mlbm/hr-ft2). Nominal R-11 conditions for the cold test are 165 psia, and 80°F±10°F. The experimental results were validated using a nuclear thermal hydraulic code VIPRE-01, MOD-02.1. The EPRI-1 correlation was being used to have a gross understanding of the CHF in the Bundles. Subsequently an empirical correlation USC11F was developed with Bundle-1 CHF database which compares favorably with experimental CHF for both the grid designs. Overall mean ratios of experimental to predicted CHF of 0.9984 and 0.9948 with standard deviations of 0.0265 and 0.0338 were obtained for Bundle-1 and Bundle-2 respectively. The predicted cold flow pressure drops also reproduced the experimental values closely. At lower mass flux a slight overprediction was encountered due to the dependability of mixing grid loss coefficient on Reynold’s number.

Development of Advanced High Heat Flux Cooling System for Power Electronics

2009 ◽  
Author(s):  
Yasuhisa Shinmoto ◽  
Shinichi Miura ◽  
Koichi Suzuki ◽  
Yoshiyuki Abe ◽  
Haruhiko Ohta
Keyword(s):  
Heat Flux ◽  
Power Electronics ◽  
Critical Heat Flux ◽  
Heating Surface ◽  
Narrow Channel ◽  
High Heat ◽  
High Heat Flux ◽  
Gap Size ◽  
Narrow Channels ◽  
Very High

Recent development in electronic devices with increased heat dissipation requires severe cooling conditions and an efficient method for heat removal is needed for the cooling under high heat flux conditions. Most researches are concentrated on small semiconductors with high heat flux density, while almost no existing researches concerning the cooling of a large semiconductor, i.e. power electronics, with high heat generation density from a large cooling area. A narrow channel between parallel plates is one of ideal structures for the application of boiling phenomena which uses the cooling for such large semiconductors. To develop high-performance cooling systems for power electronics, experiments on increase in critical heat flux (CHF) for flow boiling in narrow channels by improved liquid supply was conducted. To realize the cooling of large areas at extremely high heat flux under the conditions for a minimum gap size and a minimum flow rate of liquid supplied, the structure with auxiliary liquid supply was devised to prevent the extension of dry-patches underneath flattened bubbles generated in a narrow channel. The heating surface was experimented in two channels with different dimensions. The heating surfaces have the width of 30mm and the lengths of 50mm and 150mm in the flow direction. A large width of actual power electronics is realizable by the parallel installation of the same channel structure in the transverse direction. The cooling liquid is additionally supplied via sintered metal plates from the auxiliary unheated channels located at sides or behind the main heated channel. To supply the liquid to the entire heating surface, fine grooves are machined on the heating surface for enhance the spontaneous liquid supply by the aid of capillary force. The gap size of narrow channels are varied as 0.7mm, 2mm and 5mm. Distribution of liquid flow rate to the main heated channel and the auxiliary unheated channels were varied to investigate its effect on the critical heat flux. Test liquids employed are R113, FC72 and water. The systematic experiments by using water as a test liquid were conducted. Critical heat flux values larger than 2×106W/m2 were obtained at both gap sizes of 2mm and 5mm for a heated length of 150mm. A very high heat transfer coefficient as much as 1×105W/m2K was obtained at very high heat flux near CHF for the gap size of 2mm. This paper is a summary of experimental results obtained in the past by the present authors.

Heat Transfer Characteristics and Flow Pattern Visualization for Flow Boiling in a Vertical Narrow Microchannel

2018 ◽  
Author(s):  
Kan Zhou ◽  
Junye Li ◽  
Zhao-zan Feng ◽  
Wei Li ◽  
Hua Zhu ◽  
...  
Keyword(s):  
Heat Flux ◽  
Flow Pattern ◽  
Flow Boiling ◽  
Nucleate Boiling ◽  
Working Fluid ◽  
Inlet Temperature ◽  
Lower Mass ◽  
Subcooled Flow Boiling ◽  
Mass Fluxes ◽  
Subcooled Flow

For improving the functionality and signal speed of electronic devices, electronic components have been miniaturized and an increasing number of elements have been packaged in the device. As a result there has been a steady rise in the amount of heat necessitated to be dissipated from the electronic device. Recently microchannel heat sinks have been emerged as a kind of high performance cooling scheme to meet the heat dissipation requirement of electronics packaging, In the present study an experimental study of subcooled flow boiling in a high-aspect-ratio, one-sided heating rectangular microchannel with gap depth of 0.52 mm and width of 5 mm was conducted with deionized water as the working fluid. In the experimental operations, the mass flux was varied from 200 to 400 kg/m2s and imposed heat flux from 3 to 20 W/cm2 while the fluid inlet temperature was regulated constantly at 90 °C. The boiling curves, flow pattern and onset of nucleate boiling of subcooled flow boiling were investigated through instrumental measurements and a high speed camera. It was found that the slope of the boiling curves increased sharply once the superheat needed to initiate the onset of nucleate boiling was attained, and the slope was greater for lower mass fluxes, with lower superheat required for boiling incipience. As for the visualization images, for relatively lower mass fluxes the bubbles generated were larger and not easy to depart from the vertical upward placed narrow microchannel wall, giving elongated bubbly flow and reverse backflow. The thin film evaporation mechanism dominated the entire test section due to the elongated bubbles and transient local dryout as well as rewetting occurred. Meanwhile the initiative superheat and heat flux of onset of nucleate boiling were compared with existing correlations in the literature with good agreement.

scholarly journals A Three-Dimensional Coupled Internal/External Simulation of a Film-Cooled Turbine Vane

1999 ◽  
Author(s):  
James D. Heidmann ◽  
David L. Rigby ◽  
Ali A. Ameri
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Film Cooling ◽  
Three Dimensional ◽  
High Heat ◽  
Operating Conditions ◽  
High Heat Flux ◽  
Nasa Lewis Research ◽  
Turbine Vane ◽  
Film Cooling Holes

A three-dimensional Navier-Stokes simulation has been performed for a realistic film-cooled turbine vane using the LeRC-HT code. The simulation includes the flow regions inside the coolant plena and film cooling holes in addition to the external flow. The vane is the subject of an upcoming NASA Lewis Research Center experiment and has both circular cross-section and shaped film cooling holes. This complex geometry is modeled using a multi-block grid which accurately discretizes the actual vane geometry including shaped holes. The simulation matches operating conditions for the planned experiment and assumes periodicity in the spanwise direction on the scale of one pitch of the film cooling hole pattern. Two computations were performed for different isothermal wall temperatures, allowing independent determination of heat transfer coefficients and film effectiveness values. The results indicate separate localized regions of high heat flux in the showerhead region due to low film effectiveness and high heat transfer coefficient values, while the shaped holes provide a reduction in heat flux through both parameters. Hole exit data indicate rather simple skewed profiles for the round holes, but complex profiles for the shaped holes with mass fluxes skewed strongly toward their leading edges.

CFD Aided Design of Heat Transfer Plates for Gasketed Plate Heat Exchangers

2014 ◽  
Author(s):  
Ece Özkaya ◽  
Selin Aradag ◽  
Sadik Kakac
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Three Dimensional ◽  
Separate Flow ◽  
Working Fluid ◽  
Number Range ◽  
Plate Heat ◽  
Pressure Distributions ◽  
Cfd Analyses

In this study, three-dimensional computational fluid dynamics (CFD) analyses are performed to assess the thermal-hydraulic characteristics of a commercial Gasketed Plate Heat Exchangers (GPHEx) with 30 degrees of chevron angle (Plate1). The results of CFD analyses are compared with a computer program (ETU HEX) previously developed based on experimental results. Heat transfer plate is scanned using photogrammetric scan method to model GPHEx. CFD model is created as two separate flow zones, one for each of hot and cold domains with a virtual plate. Mass flow inlet and pressure outlet boundary conditions are applied. The working fluid is water. Temperature and pressure distributions are obtained for a Reynolds number range of 700–3400 and total temperature difference and pressure drop values are compared with ETU HEX. A new plate (Plate2) with corrugation pattern using smaller amplitude is designed and analyzed. The thermal properties are in good agreement with experimental data for the commercial plate. For the new plate, the decrease of the amplitude leads to a smaller enlargement factor which causes a low heat transfer rate while the pressure drop remains almost constant.

Numerical Study of Turbulent Heat Transfer and Pressure Drop Characteristics in a Water-Cooled Minichannel Heat Sink

2006 ◽  
Vol 129 (3) ◽  
pp. 247-255 ◽  
Author(s):  
X. L. Xie ◽  
W. Q. Tao ◽  
Y. L. He
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Pressure Drop ◽  
Wall Thickness ◽  
Heat Sink ◽  
Channel Wall ◽  
High Heat ◽  
Coolant Fluid ◽  
High Heat Flux ◽  
It Industry

With the rapid development of the Information Technology (IT) industry, the heat flux in integrated circuit (IC) chips cooled by air has almost reached its limit at about 100W∕cm2. Some applications in high technology industries require heat fluxes well beyond such a limitation. Therefore, the search for a more efficient cooling technology becomes one of the bottleneck problems of the further development of the IT industry. The microchannel flow geometry offers a large surface area of heat transfer and a high convective heat transfer coefficient. However, it has been hard to implement because of its very high pressure head required to pump the coolant fluid through the channels. A normal channel size could not give high heat flux, although the pressure drop is very small. A minichannel can be used in a heat sink with quite a high heat flux and a mild pressure loss. A minichannel heat sink with bottom size of 20mm×20mm is analyzed numerically for the single-phase turbulent flow of water as a coolant through small hydraulic diameters. A constant heat flux boundary condition is assumed. The effect of channel dimensions, channel wall thickness, bottom thickness, and inlet velocity on the pressure drop, temperature difference, and maximum allowable heat flux are presented. The results indicate that a narrow and deep channel with thin bottom thickness and relatively thin channel wall thickness results in improved heat transfer performance with a relatively high but acceptable pressure drop. A nearly optimized structure of heat sink is found that can cool a chip with heat flux of 350W∕cm2 at a pumping power of 0.314W.

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