Heat flux measurements in southwestern British Columbia: the thermal consequences of plate tectonics

1985 ◽  
Vol 22 (9) ◽  
pp. 1262-1273 ◽  
Author(s):  
T. J. Lewis ◽  
A. M. Jessop ◽  
A. S. Judge
Keyword(s):  
Heat Flux ◽  
British Columbia ◽  
Heat Flow ◽  
Heat Generation ◽  
High Heat ◽  
Heat Fluxes ◽  
Eastern Coast ◽  
Plutonic Complex ◽  
Coast Plutonic Complex ◽  
Reduced Heat Flow

Measured heat fluxes from previously published data and 34 additional boreholes outline the terrestrial heat flow field in southern British Columbia. Combined with heat generation representative of the crust at 10 sites in the Intermontane and Omineca belts, the data define a heat flow province with a reduced heat flow of 63 mW m−2 and a depth scale of 10 km. Such a linear relationship is not found or expected in the Insular Belt and the western half of the Coast Plutonic Complex where low heat fluxes are interpreted to be the result of recent subduction. The apparent boundary between low and high heat flux is a transition over a distance of 20 km, located in Jervis Inlet 20–40 km seaward of the Pleistocene Garibaldi Volcanic Belt.The warm, thin crust of the Intermontane and Omenica Crystalline belts is similar to that of areas of the Basin and Range Province where the youngest volcanics are more than 17 Ma in age. Processes 50 Ma ago that completely heated the crust and upper mantle could theoretically produce such high heat fluxes by conductive cooling of the lithosphere. But it is more likely that the asthenosphere flows towards the subduction zone, bringing heat to the base of the lithosphere. Since the reduced heat flow is high but constant, large differences in upper crustal temperatures within this heat flow province at present are caused by large variations in both crustal heat generation and near-surface thermal conductivity. The sharp transition in heat flux near the coast is the result of the combined effects of convective heating of the eastern Coast Plutonic Complex, pronounced differential uplift and erosion across a boundary within the Coast Plutonic Complex, and the subducting oceanic plate.

Magmatic evolution of the eastern Coast Plutonic Complex, Bella Coola region, west-central British Columbia

2009 ◽  
Vol 121 (9-10) ◽  
pp. 1362-1380 ◽  
Author(s):  
J. Brian Mahoney ◽  
Sarah M. Gordee ◽  
James W. Haggart ◽  
Richard M. Friedman ◽  
Larry J. Diakow ◽  
...  
Keyword(s):  
British Columbia ◽  
Eastern Coast ◽  
Magmatic Evolution ◽  
West Central ◽  
Plutonic Complex ◽  
Coast Plutonic Complex ◽  
Bella Coola

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.

Obducted nappe sequence in the San Juan Islands – northwest Cascades thrust system, Washington and British Columbia

2012 ◽  
Vol 49 (7) ◽  
pp. 796-817 ◽  
Author(s):  
E.H. Brown
Keyword(s):  
British Columbia ◽  
Detrital Zircons ◽  
San Juan ◽  
San Juan Islands ◽  
Tectonic History ◽  
Plutonic Complex ◽  
Coast Plutonic Complex ◽  
History Of ◽  
Accreted Terranes ◽  
Thrust System

The San Juan Islands – northwest Cascades thrust system in Washington and British Columbia is composed of previously accreted terranes now assembled as four broadly defined composite nappes stacked on a continental footwall of Wrangellia and the Coast Plutonic Complex. Emplacement ages of the nappe sequence are interpreted from zircon ages, field relations, and lithlogies, to young upward. The basal nappe was emplaced prior to early Turonian time (∼93 Ma), indicated by the occurrence of age-distinctive zircons from this nappe in the Sidney Island Formation of the Nanaimo Group. The emplacement age of the highest nappe in the thrust system postdates 87 Ma detrital zircons within the nappe. The nappes bear high-pressure – low-temperature (HP–LT) mineral assemblages indicative of deep burial in a thrust wedge; however, several features indicate that metamorphism occurred prior to nappe assembly: metamorphic discontinuities at nappe boundaries, absence of HP–LT assemblages in the footwall to the nappe pile, and absence of significant unroofing detritus in the Nanaimo Group. A synorogenic relationship of the thrust system to the Nanaimo Group is evident from mutually overlapping ages and by conglomerates of Nanaimo affinity that lie within the nappe pile. From the foregoing relations, and broader Cordilleran geology, the tectonic history of the nappe terranes is interpreted to involve initial accretion and subduction-zone metamorphism south of the present locality, uplift and exhumation, orogen-parallel northward transport of the nappes as part of a forearc sliver, and finally obduction at the present site over the truncated south end of Wrangellia and the Coast Plutonic Complex.

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.

Stability and Enhancement of Boiling in Microchannels

2011 ◽  
Author(s):  
A. E. Bergles
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Critical Heat Flux ◽  
High Heat ◽  
Heat Fluxes ◽  
Transfer Enhancement ◽  
The Past ◽  
The Stability ◽  
Saturated Boiling ◽  
Microelectronic Components

During the past 20 years, there has been intense worldwide interest in microchannel heat exchangers, particularly for cooling of microelectronic components. Saturated boiling of the coolant is usually indicated in order to accommodate high heat fluxes and to have uniformity of temperature. However, boiling is accompanied by several instabilities, the most severe of which can sharply limit the maximum, or critical, heat flux. These stability phenomena are reviewed, and recent studies will be discussed. Elevation of the critical heat flux will be discussed within the context of heat transfer enhancement. Means to improve the stability of boiling and the enhancement of boiling heat transfer, in general, are discussed.

Optimization of Refrigeration Systems for High-Heat-Flux Microelectronics

2008 ◽  
Author(s):  
P. E. Phelan ◽  
Y. Gupta ◽  
H. Tyagi ◽  
R. Prasher ◽  
J. Cattano ◽  
...  
Keyword(s):  
Heat Flux ◽  
Energy Consumption ◽  
System Design ◽  
High Heat ◽  
Heat Fluxes ◽  
Operating Conditions ◽  
High Heat Flux ◽  
Vapor Compression ◽  
Refrigeration System ◽  
Compressor Inlet

Increasingly, military and civilian applications of electronics require extremely high heat fluxes, on the order of 1000 W/cm2. Thermal management solutions for these severe operating conditions are subject to a number of constraints, including energy consumption, controllability, and the volume or size of the package. Calculations indicate that the only possible approach to meeting this heat flux condition, while maintaining the chip temperature below 50 °C, is to utilize refrigeration. Here we report an initial optimization of the refrigeration system design. Because the outlet quality of the fluid leaving the evaporator must be held to approximately less than 20%, in order to avoid reaching critical heat flux, the refrigeration system design is dramatically different from typical configurations for household applications. In short, a simple vapor-compression cycle will require excessive energy consumption, largely because of the superheat required to return the refrigerant to its vapor state before the compressor inlet. A better design is determined to be a “two-loop” cycle, in which the vapor-compression loop is coupled thermally to a primary loop that directly cools the high-heat-flux chip.

scholarly journals Deterioration in Heat Transfer to Fluids at Supercritical Pressure and High Heat Fluxes

1969 ◽  
Vol 91 (1) ◽  
pp. 27-36 ◽  
Author(s):  
B. S. Shiralkar ◽  
Peter Griffith
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
High Heat ◽  
Supercritical Pressure ◽  
Heat Fluxes ◽  
Bulk Temperature ◽  
Operating Pressure ◽  
The Heat Transfer Coefficient

At slightly supercritical pressure and in the neighborhood of the pseudocritical temperature (which corresponds to the peak in the specific heat at the operating pressure), the heat transfer coefficient between fluid and tube wall is strongly dependent on the heat flux. For large heat fluxes, a marked deterioration takes place in the heat transfer coefficient in the region where the bulk temperature is below the pseudocritical temperature and the wall temperature above the pseudocritical temperature. Equations have been developed to predict the deterioration in heat transfer at high heat fluxes and the results compared with previously available results for steam. Experiments have been performed with carbon dioxide for additional comparison. Limits of safe operation for a supercritical pressure heat exchanger in terms of the allowable heat flux for a particular flow rate have been determined theoretically and experimentally.

Integrated Vapor Chamber Heat Spreader for Power Module Applications

2017 ◽  
Author(s):  
Clayton L. Hose ◽  
Dimeji Ibitayo ◽  
Lauren M. Boteler ◽  
Jens Weyant ◽  
Bradley Richard
Keyword(s):  
Heat Flux ◽  
Thermal Resistance ◽  
Power Electronics ◽  
Coefficient Of Thermal Expansion ◽  
High Heat ◽  
Heat Fluxes ◽  
High Heat Flux ◽  
Vapor Chamber ◽  
Power Module ◽  
Heat Spreader

This work presents a demonstration of a coefficient of thermal expansion (CTE) matched, high heat flux vapor chamber directly integrated onto the backside of a direct bond copper (DBC) substrate to improve heat spreading and reduce thermal resistance of power electronics modules. Typical vapor chambers are designed to operate at heat fluxes > 25 W/cm2 with overall thermal resistances < 0.20 °C/W. Due to the rising demands for increased thermal performance in high power electronics modules, this vapor chamber has been designed as a passive, drop-in replacement for a standard heat spreader. In order to operate with device heat fluxes >500 W/cm2 while maintaining low thermal resistance, a planar vapor chamber is positioned onto the backside of the power substrate, which incorporates a specially designed wick directly beneath the active heat dissipating components to balance liquid return and vapor mass flow. In addition to the high heat flux capability, the vapor chamber is designed to be CTE matched to reduce thermally induced stresses. Modeling results showed effective thermal conductivities of up to 950 W/m-K, which is 5 times better than standard copper-molybdenum (CuMo) heat spreaders. Experimental results show a 43°C reduction in device temperature compared to a standard solid CuMo heat spreader at a heat flux of 520 W/cm2.

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