Subcooled Flow Boiling in Mini and Micro Channel: Contribution Toward High Heat Flux Cooling Technology for Electronics

2009 ◽  
Author(s):  
Tomoyuki Nomura ◽  
Michael V. Shustov ◽  
Koichi Suzuki ◽  
Chungpyo Hong ◽  
Yury A. Kuzma-Kichta
Keyword(s):  
Heat Flux ◽  
Liquid Velocity ◽  
Flow Boiling ◽  
Heating Surface ◽  
Heat Fluxes ◽  
High Heat Flux ◽  
Subcooled Flow Boiling ◽  
Maximum Heat ◽  
Subcooled Flow ◽  
Micro Channels

Subcooled flow boiling has been investigated for horizontal mini and micro channels of which hydraulic diameters are 1mm and 150μm, respectively for high heat flux cooling in electronics. The heating surface is 1mm in width and 10mm in length for the mini channel. Eleven micro grooving are made on the copper heating block of 5.25mm×5.25mm. Aqueous solutions of ethanol, 10% and 50% in mass concentration, are used as boiling liquid for the micro channel. Microbubble emission boiling (MEB) of water is generated at liquid subcooling of 40K in the mini channel as same cases of conventional macro channels and the maximum heat flux obtained is a 10MW/m2 at liquid velocity of 1m/s (1000kg/m2s). However, the boiling turns to film boiling at low liquid velocity, 0.3m/s (300kg/m2s) for an example. In subcooled boiling of aqueous solutions, the heat flux becomes small for the lower ethanol concentration. The critical heat fluxes are well agreed with the existing theories and the maximum heat fluxes are higher than CHF. However, no micro bubble emission boiling is observed in subcooled flow boiling of mini channels and the CHF is considerably smaller than the existing theories. It is difficult to generate MEB for micro channels with heating surface of large thermal capacity because the coalescing bubbles formed on the heating surface are filled up in the channel and the liquid vapor exchange is disturbed.

Subcooled Flow Boiling in a Minichannel

2009 ◽  
Author(s):  
Akira Oshima ◽  
Koichi Suzuki ◽  
Chungpyo Hong ◽  
Masataka Mochizuki
Keyword(s):  
Heat Flux ◽  
High Speed ◽  
Flow Boiling ◽  
Heating Surface ◽  
Nucleate Boiling ◽  
High Heat Flux ◽  
Subcooled Flow Boiling ◽  
Maximum Heat ◽  
High Speed Video ◽  
Subcooled Flow

It has been considered that the dry-out is easy to occur in boiling heat transfer for a small channel, a mini or microchannel because the channel was easily filled with coalescing vapor bubbles. In the present study, the experiments of subcooled flow boiling of water were performed under atmospheric condition for a horizontal rectangular channel of which size is 1mm in height and 1mm in width with a flat heating surface of 10mm in length and 1mm in width placed on the bottom of the channel. The heating surface is a top of copper heating block and heated by ceramics heaters. In the high heat flux region of nucleate boiling, about 70 ∼ 80 percent of heating surface was covered with a large coalescing bubble and the boiling reached critical heat flux (CHF) by a high speed video observation. In the beginning of transition boiling, coalescing bubbles were collapsed to many fine bubbles and microbubble emission boiling was observed at higher liquid subcooling than 30K. The maximum heat flux obtained was 8MW/m2 (800W/cm2) at liquid subcooling of higher than 40K and the liquid velocity of 0.5m/s. However, the surface temperature was extremely higher than that of centimeter scale channel. The high speed video photographs indicated that microbubble emission boiling occurs in the deep transition boiling region.

Subcooled Flow Boiling With Microbubble Emission in a Michrochannel

2009 ◽  
Author(s):  
Koichi Suzuki ◽  
Tomoyuki Nomura ◽  
Chungpyo Hong ◽  
Kazuhisa Yuki
Keyword(s):  
Heat Flux ◽  
Liquid Velocity ◽  
Flow Boiling ◽  
Atmospheric Condition ◽  
High Heat ◽  
Hydraulic Diameter ◽  
Maximum Pressure ◽  
High Heat Flux ◽  
Subcooled Flow Boiling ◽  
Subcooled Flow

Subcooled flow boiling of water has been investigated for the horizontal multi-microchannel of which hydraulic diameter is 150μm for unit channel. Eleven rectangular microchannels are made on a top of copper heating block of 5.25mm × 5.25mm. The outlet of the channel is opened to the atmospheric surroundings and the maximum pressure in the channel is lower than 25mmHg. The boiling test is performed under the nearly atmospheric condition. The experimental results are discussed compared with subcooled boiling of water in a microchannel of 155μm in hydraulic diameter with Platinum film microheater of 2000μm in length and 200μm in width obtained by Ping Cheng and his co-workers. According to the authors’ previous experiments on subcooled flow boiling in mini and conventional channels, the critical heat flux decreases with decreasing of the hydraulic diameter of the channel. The boiling in the microchannel turns to film boiling after reaching CHF without microbubble emission boiling (MEB) regardless of liquid subcooling and liquid velocity even if the boiling condition is the same as MEB in the minichannels. In the high heat flux region, whole of the microchannels is completely covered with large coalescing bubbles. The results are much different from those of experiments with Platinum film microheater, which have 14.41 MW/m2 of heat flux in MEB. It is difficult to introduce liquid–vapor exchange including MEB for the large capacitance heat sink in microchannel boiling.

Heat Transfer Enhancement in Compact Phase Change Microchannel Heat Exchangers for High Flux Laser Diodes

2018 ◽  
Author(s):  
Jensen Hoke ◽  
Todd Bandhauer ◽  
Jack Kotovsky ◽  
Julie Hamilton ◽  
Paul Fontejon
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Phase Change ◽  
Flow Boiling ◽  
Laser Diodes ◽  
High Heat ◽  
Heat Fluxes ◽  
High Heat Flux ◽  
Maximum Heat ◽  
Average Maximum

Liquid-vapor phase change heat transfer in microchannels offers a number of significant advantages for thermal management of high heat flux laser diodes, including reduced flow rates and near constant temperature heat rejection. Modern laser diode bars can produce waste heat loads >1 kW cm−2, and prior studies show that microchannel flow boiling heat transfer at these heat fluxes is possible in very compact heat exchanger geometries. This paper describes further performance improvements through area enhancement of microchannels using a pyramid etching scheme that increases heat transfer area by ∼40% over straight walled channels, which works to promote heat spreading and suppress dry-out phenomenon when exposed to high heat fluxes. The device is constructed from a reactive ion etched silicon wafer bonded to borosilicate to allow flow visualization. The silicon layer is etched to contain an inlet and outlet manifold and a plurality of 40μm wide, 200μm deep, 2mm long channels separated by 40μm wide fins. 15μm wide 150μm long restrictions are placed at the inlet of each channel to promote uniform flow rate in each channel as well as flow stability in each channel. In the area enhanced parts either a 3μm or 6μm sawtooth pattern was etched vertically into the walls, which were also scalloped along the flow path with the a 3μm periodicity. The experimental results showed that the 6μm area-enhanced device increased the average maximum heat flux at the heater to 1.26 kW cm2 using R134a, which compares favorably to a maximum of 0.95 kw cm2 dissipated by the plain walled test section. The 3μm area enhanced test sections, which dissipated a maximum of 1.02 kW cm2 showed only a modest increase in performance over the plain walled test sections. Both area enhancement schemes delayed the onset of critical heat flux to higher heat inputs.

A theoretical and experimental study on subcooled flow boiling at high heat flux

1994 ◽  
Vol 29 (5) ◽  
pp. 319-327 ◽  
Author(s):  
K. W. Lin ◽  
C. H. Lee ◽  
L. W. Hourng ◽  
J. C. Hsu
Keyword(s):  
Experimental Study ◽  
Heat Flux ◽  
Flow Boiling ◽  
High Heat ◽  
High Heat Flux ◽  
Subcooled Flow Boiling ◽  
Subcooled Flow

High Heat Flux Subcooled Flow Boiling of Methanol in Microtubes

2015 ◽  
Author(s):  
Farzad Houshmand ◽  
Hyoungsoon Lee ◽  
Mehdi Asheghi ◽  
Kenneth E. Goodson
Keyword(s):  
Heat Flux ◽  
Pressure Drop ◽  
Flow Boiling ◽  
High Heat ◽  
Heat Fluxes ◽  
Two Phase ◽  
Subcooled Flow Boiling ◽  
Subcooled Flow ◽  
Inner Diameter ◽  
Phase Pressure

As the proper cooling of the electronic devices leads to significant increase in the performance, two-phase heat transfer to dielectric liquids can be of an interest especially for thermal management solutions for high power density devices with extremely high heat fluxes. In this paper, the pressure drop and critical heat flux (CHF) for subcooled flow boiling of methanol at high heat fluxes exceeding 1 kW/cm2 is investigated. Methanol was propelled into microtubes (ID = 265 and 150 μm) at flow rates up to 40 ml/min (mass fluxes approaching 10000 kg/m2-s), boiled in a portion of the microtube by passing DC current through the walls, and the two-phase pressure drop and CHF were measured for a range of operating parameters. The two-phase pressure drop for subcooled flow boiling was found to be significantly lower than the saturated flow boiling case, which can lead to lower pumping powers and more stability in the cooling systems. CHF was found to be increasing almost linearly with Re and inverse of inner diameter (1/ID), while for a given inner diameter, it decreases with increasing heated length.

E219 High Heat Flux Cooling for Electronic Devices by Subcooled Flow Boiling : Cooing performance of small channel

2001 ◽  
Vol 2001 (0) ◽  
pp. 553-554
Author(s):  
Koichi SUZUKI ◽  
Hiroki SAITO ◽  
Hiroshi KAWAMURA ◽  
Hideo IWASAKI ◽  
Koichiro KAWANO ◽  
...  
Keyword(s):  
Heat Flux ◽  
Flow Boiling ◽  
Electronic Devices ◽  
High Heat ◽  
High Heat Flux ◽  
Subcooled Flow Boiling ◽  
Small Channel ◽  
Subcooled Flow

High heat flux burnout in subcooled flow boiling

1995 ◽  
Vol 4 (3) ◽  
pp. 151-161
Author(s):  
G. P. Celata ◽  
M. Cumo ◽  
A. Mariani
Keyword(s):  
Heat Flux ◽  
Flow Boiling ◽  
High Heat ◽  
High Heat Flux ◽  
Subcooled Flow Boiling ◽  
Subcooled Flow

A Photographic study of subcooled flow boiling burnout at high heat flux and velocity

2007 ◽  
Vol 50 (1-2) ◽  
pp. 283-291 ◽  
Author(s):  
G.P. Celata ◽  
M. Cumo ◽  
D. Gallo ◽  
A. Mariani ◽  
G. Zummo
Keyword(s):  
Heat Flux ◽  
Flow Boiling ◽  
High Heat ◽  
High Heat Flux ◽  
Subcooled Flow Boiling ◽  
Subcooled Flow

Single-Side Heated Monoblock, High Heat Flux Removal Using Water Subcooled Flow Boiling

2003 ◽  
Author(s):  
Ronald D. Boyd ◽  
Ali Ekhlassi ◽  
Penrose Cofie ◽  
Richard Martin ◽  
Hongtao Zhang
Keyword(s):  
Heat Flux ◽  
Wall Temperature ◽  
Test Section ◽  
Flow Boiling ◽  
Three Dimensional ◽  
High Heat ◽  
High Heat Flux ◽  
Subcooled Flow Boiling ◽  
Subcooled Flow ◽  
Single Side

Plasma-facing components for fusion reactors and other high heat flux heat sinks are usually subjected to a peripherally non-uniform heat flux. The configuration under study is related to these applications and consists of a single-side heated monoblock cross-section test section with a circular coolant channel bored through the center. The monoblock test section has a heated length of 180.0 mm and has 10.0 mm and 30.0 mm inside diameter and outside square sides, respectively. It was subjected to a constant heat flux on one side only, and the remaining portion of the outside surfaces is not exposed to a heat flux. The inlet channel water temperature was held near at 26.0°C, the exit pressure was maintained at 0.207 MPa, and the mass velocity was 0.59 Mg/m2s. The results consist of three-dimensional monoblock test section wall temperature distributions and a clear display of both critical heat flux and post-critical heat flux for this single-side heated configuration. These results are very encouraging in that they are among the first full set of truly three-dimensional monoblock test section wall temperature measurements for a one-side heated monoblock flow channel which contains the effects of conjugate heat transfer for turbulent, subcooled flow boiling. Comparisons are made between these results for the monoblock test section and those for a single-side heated circular test section.

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