Shallow Water Heat Flow Measurements in Bras D'or Lake, Nova Scotia

1971 ◽  
Vol 8 (1) ◽  
pp. 96-101 ◽  
Author(s):  
Douglas S. Rankin ◽  
Roy D. Hyndman
Keyword(s):  
Heat Flux ◽  
Nova Scotia ◽  
Heat Flow ◽  
Surface Temperature ◽  
Shallow Water ◽  
Thermal Gradient ◽  
Light Weight ◽  
Flow Measurements ◽  
Made In ◽  
Conductivity Contrast

A light-weight oceanic thermal gradient probe was used for heat flow studies in Bras d'Or Lake, Nova Scotia. The measurements were made in St. Andrew's Channel, an elongated trough 270 m deep and 540 m wide. The heat flux of 1.50 μcal/cm2 s (63 mW/m2) is corrected for sedimentation, conductivity contrast, topography, and surface temperature differences.

scholarly journals In situ determination of heat flow in unconsolidated sediments

Geophysics ◽  
1981 ◽  
Vol 46 (1) ◽  
pp. 76-83 ◽  
Author(s):  
J. H. Sass ◽  
J. P. Kennelly ◽  
W. E. Wendt ◽  
T. H. Moses ◽  
J. P. Ziagos
Keyword(s):  
Heat Flow ◽  
Thermal Gradient ◽  
Equilibrium Temperature ◽  
Unconsolidated Sediments ◽  
Heat Sources ◽  
Geothermal Resources ◽  
Flow Measurements ◽  
Thermal Measurements

Subsurface thermal measurements are the most effective, least ambiguous tools for locating geothermal resources. Measurements of thermal gradient in the upper few tens of meters can delineate the major anomalies, but it is also desirable to combine these gradients with reliable estimates of thermal conductivity, to provide data on the energy flux and to constrain models of the heat sources responsible for the anomalies. Problems associated with such heat flow measurements include the economics of casing or grouting holes, the long waits and repeated visits necessary to obtain equilibrium temperature values, the possible legal liability arising from disturbance of aquifers, the hazards presented by pipes protruding from the ground, and the security problems associated with leaving cased holes open for periods of weeks to months.

Heat flow in the Bushveld Complex, South Africa: implications for upper mantle structure

2017 ◽  
Vol 120 (3) ◽  
pp. 351-370 ◽  
Author(s):  
M.Q.W. Jones
Keyword(s):  
South Africa ◽  
Thermal Conductivity ◽  
Heat Flux ◽  
Heat Flow ◽  
Seismic Tomography ◽  
Upper Mantle ◽  
Bushveld Complex ◽  
Kaapvaal Craton ◽  
Flow Measurements ◽  
Witwatersrand Basin

Abstract Geothermal measurements in South Africa since 1939 have resulted in a good coverage of heat flow observations. The Archaean Kaapvaal Craton, in the central part of South Africa, is the best-studied tectonic domain, with nearly 150 heat flow measurements. The greatest density of heat flow sites is in the Witwatersrand Basin goldfields, where geothermal data are essential for determining refrigeration requirements of deep (up to 4 km) gold mines; the average heat flow is 51 ± 6mWm-2. The Bushveld Complex north of the Witwatersrand Basin is an extensive 2.06 Ga ultramafic-felsic intrusive complex that hosts the world’s largest reserves of platinum. The deepest platinum mines reach ~2 km and the need for thermal information for mine refrigeration engineering has led to the generation of a substantial geothermal database. Nearly 1000 thermal conductivity measurements have been made on rocks constituting the Bushveld Complex, and borehole temperature measurements have been made throughout the Complex. The temperature at maximum rock-breaking depth (~2.5 km) is 70°C, approximately 30°C higher than the temperature at equivalent depth in the Witwatersrand Basin; the thermal gradient in the Bushveld Complex is approximately double that in the Witwatersrand Basin. The main reason for this is the low thermal conductivity of rocks overlying platinum mines. The Bushveld data also resulted in 31 new estimates for the heat flux through the Earth’s crust. The overall average value for the Bushveld, 47 ± 7 mW m-2, is the same, to within statistical error, as the Witwatersrand Basin average. The heat flow for platinum mining areas (45 mW m-2) and the heat flux into the floor of the Witwatersrand Basin (43 mW m-2) are typical of Archaean cratons world-wide. The temperature structure of the Kaapvaal lithosphere calculated from the Witwatersrand geothermal data is essentially the same as that derived from thermobarometric studies of Cretaceous kimberlite xenoliths. Both lines of evidence lead to an estimated heat flux of ~17 mW m-2 for the mantle below the Kaapvaal Craton. The estimated thermal thickness of the Kaapvaal lithosphere (235 km) is similar to that defined on the basis of seismic tomography and magnetotelluric studies. The lithosphere below the Bushveld Complex is not significantly hotter than that below the Witwatersrand Basin. This favours a chemical origin rather than a thermal origin for the upper mantle anomaly below the Bushveld Complex that has been identified by seismic tomography studies and magnetotelluric soundings.

A discussion on the structure and evolution of the Red Sea and the nature of the Red Sea, Gulf of Aden and Ethiopia rift junction - A review of Red Sea heat flow

1970 ◽  
Vol 267 (1181) ◽  
pp. 191-203 ◽  
Keyword(s):  
Heat Flow ◽  
Red Sea ◽  
High Heat ◽  
Temperature Measurements ◽  
High Heat Flow ◽  
Flow Measurements ◽  
The World ◽  
Brine Pools ◽  
Deep Exploration ◽  
Made In

There are now twelve heat flow measurements in the Red Sea made with heat flow probes from survey ships and several sets of temperature measurements made in deep exploration boreholes. The oceanic measurements are in water depths ranging from 0.94 to 2.70 km and all but one of these measurements give values significantly higher than the world mode of 46 mW m -2 (1.1 ). They include the world record high oceanic measurement of more than 3307 mW m -2 (79.0) in the neighbourhood of the hot brine pools. These measurements show that the deep axial trough of the Red Sea is associated with high heat flow, the values being similar to those found in the mid-Indian Ocean rift, the mid-Atlantic rift and over the crest of the East Pacific rise. It is of considerable interest to see if there is also high heat flow over the Red Sea margins and the main purpose of this paper is to examine temperature data from deep exploration boreholes. The boreholes are drilled mainly in rock salt, sandstones and shales. A discussion is given of the thermal conductivities assumed for these rocks. The boreholes have depths of up to 4 km and in some cases the temperature measurements enable an estimate to be made of the heat flow. These are also found to be high. The significance of the high heat flow to ideas concerning the structure and evolution of the Red Sea is discussed.

Heat flow measurements under some lakes in the Superior Province of the Canadian Shield

1979 ◽  
Vol 16 (10) ◽  
pp. 1951-1964 ◽  
Author(s):  
R. G. Allis ◽  
G. D. Garland
Keyword(s):  
Heat Flow ◽  
High Heat ◽  
Flow Measurements ◽  
Average Heat ◽  
Heat Flows ◽  
Climatic Variations ◽  
Northwestern Ontario ◽  
Flow Heat ◽  
Lateral Heat ◽  
Made In

Six heat flow values have been obtained from measurements made in the sediments of thermally-stable lakes in four major structural belts of northwestern Ontario. Each heat flow is the average of measurements from 3–6 neighbouring lakes. Corrections for the thermal history, lateral heat flow, sedimentation, and refraction effects have been applied. High heat flows which were measured in the Quetico gneiss superbelt (77 mW/m2) and on the Indian Lake intrusion in the Wabigoon superbelt (64 mW/m2) are related to above-average heat productivities at these locations, but the extent in depth of the sources is shown to be very different in the two cases. The consistency of the lake results with borehole measurements, on a heat flow – heat productivity plot, strongly suggests that the former are not perturbed by recent climatic variations.

Oceanic heat flow measurements over the continental margins of eastern Canada

1976 ◽  
Vol 13 (8) ◽  
pp. 1031-1038 ◽  
Author(s):  
J. F. Lewis ◽  
R. D. Hyndman
Keyword(s):  
Nova Scotia ◽  
Heat Flow ◽  
Numerical Models ◽  
Continental Margins ◽  
Eastern Canada ◽  
Flow Measurements ◽  
Grand Banks ◽  
The Mean ◽  
Seismic Reflection Profiles ◽  
Heat Flow Variations

Sixteen heat flow measurements have been obtained on the continental rise and slope off Nova Scotia and off the southern Grand Banks of Newfoundland. The mean of the 14 most reliable values is 48 ± 4 mW m−2 (1.15 ± 0.09 μcal cm−2 s−1), which is in agreement with the mean for previous measurements on ocean floor of age greater than 100 m.y. However, the heat flux from the crust indicated by the new values is significantly lower because of the heat produced in the some 5 km of terrigenous sediments underlying the stations. The low values could represent an edge effect between continent and ocean. Two lines of stations across the Nova Scotia rise show large heat flow variations. Numerical models indicate that the variations could arise from thermal refraction by high thermal conductivity salt, which probably constitutes the 'sedimentary ridge complex' outlined by deep seismic reflection profiles. The salt or evaporites formed in the restricted basin that was parallel to this rifted margin during the first phase of opening of the Atlantic Ocean. The heat flow variations measured on a profile perpendicular to the southern edge of the Grand Banks are smaller. This margin was a transform fault between Newfoundland and northwest Africa during the early ocean opening, so that the seafloor in the region of the profile was produced after the restricted basin phase of evaporite formation.

scholarly journals Experimental Determination of the Heat Transfer Coefficient of Real Cooled Geometry Using Linear Regression Method

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 180
Author(s):  
Asif Ali ◽  
Lorenzo Cocchi ◽  
Alessio Picchi ◽  
Bruno Facchini
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Linear Regression ◽  
Surface Temperature ◽  
Transfer Coefficient ◽  
External Surface ◽  
Internal Surface ◽  
Regression Method ◽  
Thermal Transient

The scope of this work was to develop a technique based on the regression method and apply it on a real cooled geometry for measuring its internal heat transfer distribution. The proposed methodology is based upon an already available literature approach. For implementation of the methodology, the geometry is initially heated to a known steady temperature, followed by thermal transient, induced by injection of ambient air to its internal cooling system. During the thermal transient, external surface temperature of the geometry is recorded with the help of infrared camera. Then, a numerical procedure based upon a series of transient finite element analyses of the geometry is applied by using the obtained experimental data. The total test duration is divided into time steps, during which the heat flux on the internal surface is iteratively updated to target the measured external surface temperature. The final procured heat flux and internal surface temperature data of each time step is used to find the convective heat transfer coefficient via linear regression. This methodology is successfully implemented on three geometries: a circular duct, a blade with U-bend internal channel, and a cooled high pressure vane of real engine, with the help of a test rig developed at the University of Florence, Italy. The results are compared with the ones retrieved with similar approach available in the open literature, and the pros and cons of both methodologies are discussed in detail for each geometry.

High-output diesel engine heat transfer: Part 1 - comparison between piston heat flux and global energy balance

2021 ◽  
pp. 146808742110170
Author(s):  
Eric Gingrich ◽  
Michael Tess ◽  
Vamshi Korivi ◽  
Jaal Ghandhi
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Diesel Engine ◽  
Surface Temperature ◽  
Fast Response ◽  
Temperature Data ◽  
Start Of Injection ◽  
Local Measurements ◽  
Surface Temperature Data ◽  
High Output

High-output diesel engine heat transfer measurements are presented in this paper, which is the first of a two-part series of papers. Local piston heat transfer, based on fast-response piston surface temperature data, is compared to global engine heat transfer based on thermodynamic data. A single-cylinder research engine was operated at multiple conditions, including very high-output cases – 30 bar IMEPg and 250 bar in-cylinder pressure. A wireless telemetry system was used to acquire fast-response piston surface temperature data, from which heat flux was calculated. An interpolation and averaging procedure was developed and a method to recover the steady-state portion of the heat flux based on the in-cylinder thermodynamic state was applied. The local measurements were spatially integrated to find total heat transfer, which was found to agree well with the global thermodynamic measurements. A delayed onset of the rise of spatially averaged heat flux was observed for later start of injection timings. The dataset is internally consistent, for example, the local measurements match the global values, which makes it well suited for heat transfer correlation development; this development is pursued in the second part of this paper.

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