Thermal Wave Based Measurement of Liquid Thermal Conductivities

2008 ◽  
Author(s):  
Zhefu Wang ◽  
Richard B. Peterson
Keyword(s):  
Thermal Conductivity ◽  
Stainless Steel ◽  
Thermal Properties ◽  
Steel Strip ◽  
Measurement Techniques ◽  
Temperature Response ◽  
Front Surface ◽  
Conduction Model ◽  
Closed Chamber ◽  
Thermal Conductivities

This work develops an experimental technique capable of determining thermal conductivity of liquids with application to nanofluids. A periodic current passing through a thin stainless steel strip generates a periodic Joule heating source and an infrared detector measures the temperature response at the front surface of the stainless steel strip. An open chamber is machined out of a delrin plate with the stainless steel strip acting as the sealing cover. This resulting closed chamber contains the test liquid. The phase and magnitude of the temperature response were measured using a lock-in amplifier at various frequencies from 22 to 502 Hz. A one-dimensional, two-layered transient heat conduction model was developed to predict the temperature response on the front surface of the stainless steel strip. This temperature response, including phase and magnitude, is a function of the thermal properties of the liquid. The phase information shows high sensitivity to thermal properties of the liquid layer and is employed to match experimental data to find thermal conductivities. The measured thermal conductivities of water and ethylene glycol agree well with data from the literature and support the validity of this measurement technique. An aqueous fluid consisting of gold nanoparticles was tested. Anomalous thermal conductivity enhancement was observed. Our measurement results also show a divergence of thermal transport behavior between nanofluids and pure liquids. This suggests the need to carefully examine the role of measurement techniques in the study of nanofluid heat transfer phenomena.

A Phase-Sensitive Technique for Measurements of Liquid Thermal Conductivity

2010 ◽  
Vol 132 (5) ◽  
Author(s):  
Zhefu Wang ◽  
Richard B. Peterson
Keyword(s):  
Thermal Conductivity ◽  
Stainless Steel ◽  
Thermal Properties ◽  
Steel Strip ◽  
Infrared Detector ◽  
Temperature Response ◽  
Front Surface ◽  
Test Liquid ◽  
Conduction Model ◽  
Conductivity Enhancement

An experimental technique based on the thermal wave approach for measuring the thermal conductivity of liquids is developed in this paper. A stainless steel strip functions as both a heating element and a sealing cover for a chamber containing a test liquid. A periodic current passing through this metal strip generates a periodic Joule heating source. An infrared detector measures the temperature response at the front surface of the stainless steel strip. The phase and magnitude of the temperature response with respect to the heating signal were measured by a lock-in amplifier at various frequencies from 22 Hz to 502 Hz. A one-dimensional, two-layered transient heat conduction model was developed to predict the temperature response on the front surface of the stainless steel strip. The phase information from this temperature response shows high sensitivity to the change in thermal properties of the liquid layer and is employed to match experimental data to find the thermal properties of the test liquid. The measured thermal conductivities of water and ethylene glycol agree quite well with the data from literature and support the validity of this measurement technique. An aqueous fluid consisting of gold nanoparticles is tested and anomalous thermal conductivity enhancement is observed. A discrepancy in the thermal transport behavior between pure liquids and nanofluids is suggested from our experimental results.

A Phase-Sensitive Technique for the Thermal Characterization of Dielectric Thin Films

1999 ◽  
Vol 121 (3) ◽  
pp. 528-536 ◽  
Author(s):  
S. W. Indermuehle ◽  
R. B. Peterson
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Specific Heat ◽  
Temperature Response ◽  
Front Surface ◽  
Thermal Characterization ◽  
Fused Silica ◽  
Dielectric Thin Films ◽  
Phase Sensitive

A phase-sensitive measurement technique for determining two independent thermal properties of a thin dielectric film is presented. The technique involves measuring a specimen’s front surface temperature response to a periodic heating signal over a range of frequencies. The phase shift of the temperature response is fit to an analytical model using thermal diffusivity and effusivity as fitting parameters, from which the thermal conductivity and specific heat can be calculated. The method has been applied to 1.72-μm thick films of SiO2 thermally grown on a silicon substrate. Thermal properties were obtained through a temperature range from 25°C to 300°C. One interesting outcome stemming from analysis of the experimental data is the ability to extract both thermal conductivity and specific heat of a thin film from phase information alone. The properties obtained with this method are slightly below the bulk values for fused silica with a measured room temperature (25°C) thermal conductivity of 1.28 ± 0.12 W/m-K.

Laser Flash Measurement of Samples With a Transparent Reference Layer

2009 ◽  
Author(s):  
Heng Ban ◽  
Zilong Hua
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Temperature Response ◽  
Front Surface ◽  
Laser Flash ◽  
Laser Flash Method ◽  
Flash Method ◽  
Thermal Diffusivity Measurement ◽  
Reference Layer

The laser flash method is a standard method for thermal diffusivity measurement. This paper reports the development of a method and theory that extends the standard laser flash method to measure thermal conductivity and thermal diffusivity simultaneously. By attaching a transparent reference layer with known thermal properties on the back of a sample, the thermal conductivity and thermal diffusivity of the sample can be extracted from the temperature response of the interface between the sample and the reference layer to a heating pulse on the front surface. The theory can be applied for sample and reference layer with different thermal properties and thickness, and the original analysis of the laser flash method becomes a limiting case of the current theory with an infinitely small thickness of the reference layer. The uncertainty analysis was performed and results indicated that the laser flash method can be used to extract the thermal conductivity and diffusivity of the sample. The results can be applied to, for instance, opaque liquid in a quartz dish with silicon infrared detector measuring the temperature of liquid-quartz interface through the quartz.

Dissimilar Materials Laser Welding Characteristics of Stainless Steel and Titanium Alloy

2013 ◽  
Vol 465-466 ◽  
pp. 1060-1064 ◽  
Author(s):  
Zazuli Mohid ◽  
M.A. Liman ◽  
M.R.A. Rahman ◽  
N.H. Rafai ◽  
Erween Abdul Rahim
Keyword(s):  
Thermal Conductivity ◽  
Stainless Steel ◽  
Titanium Alloy ◽  
Thermal Properties ◽  
Material Properties ◽  
Dissimilar Materials ◽  
Scanning Speed ◽  
Welding Parameters ◽  
Melting Region ◽  
Offset Distance

Welding parameters are directly influenced by the work material properties. Thermal properties such as thermal conductivity and melting point are very important to estimate the range of power required and the allowable scanning speed. However, when two or more different materials are involved, modifying lasing parameters are not enough to counter the problems such as imbalance melting region and weak adhesion of contact surface. To counter this problem, the characteristics of welding beads formation for both materials need to be clarified. In this study, comparison of welding beads constructed using the same scanning parameters were done to understand the different and similarity of melted region for the both materials. Actual welding of the both materials were done under different offset distance to obtain a balanced melting area and well mixed melting region.

Thermal properties of pillared-graphene nanostructures

2015 ◽  
Vol 1727 ◽  
Author(s):  
M. Rifu ◽  
K. Shintani
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Molecular Dynamics ◽  
Thermal Properties ◽  
Molecular Dynamics Simulation ◽  
Dynamics Simulation ◽  
Nonequilibrium Molecular Dynamics ◽  
Nonequilibrium Molecular Dynamics Simulation ◽  
Thermal Conductivities ◽  
Graphene Nanostructures

ABSTRACTThe thermal conductivities of pillared-graphene nanostructures (PGNSs) are obtained using nonequilibrium molecular-dynamics simulation. It is revealed their thermal conductivities are much smaller than the thermal conductivities of carbon nanotubes (CNTs). This fact is explained by examining the density of states (DOS) of the local phonons of PGNSs. It is also found the thermal conductivity of a PGNS linearly decreases with the increase of the inter-pillar distance.

Effect of CaO on Thermal Conductivities of Mg and Mg-Zn Alloys

2014 ◽  
Vol 783-786 ◽  
pp. 437-442 ◽  
Author(s):  
Gun Young Oh ◽  
Dae Guen Kim ◽  
Young Gyu Yoo ◽  
Young Ok Yoon ◽  
Shae K. Kim ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Mechanical Property ◽  
Thermal Properties ◽  
Specific Heat ◽  
Room Temperature ◽  
Die Casting ◽  
Steel Mold ◽  
Process Ability ◽  
Zn Alloys ◽  
Thermal Conductivities

The thermal conductivities of binary Mg-CaO and Mg-Zn, and ternary Mg-Zn-CaO alloys have been investigated by evaluating the effect of CaO on pure Mg and Mg-Zn alloys, with an emphasis to develop a new Mg alloy by compromising thermal conductivity, process-ability and mechanical property. The Mg alloys specimens were prepared by casting into a steel mold and then by machining. The thermal conductivities of the alloys were determined by evaluating the thermal properties of specific heat and diffusivity, from room temperature to 200 °C. OM, SEM, and EDS were used to analyze the microstructures and phases. The fluidity was also investigated by using a spiral fluidity mold for improved process-ability during actual die casting.

scholarly journals The thermal properties of the Mercia Mudstone Group

2020 ◽  
pp. qjegh2020-098
Author(s):  
Dan Parkes ◽  
Jon Busby ◽  
Simon J. Kemp ◽  
Estelle Petitclerc ◽  
Ian Mounteney
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Geometric Mean ◽  
Correction Factors ◽  
Electrical Cable ◽  
Heating And Cooling ◽  
Ground Source ◽  
Thermal Diffusivities ◽  
Borehole Core ◽  
Thermal Conductivities

The Mercia Mudstone Group (MMG) crops out extensively across England and Wales and its thermal properties are required for the design of infrastructure such as ground source heating and cooling schemes and electrical cable conduits. Data from the literature and new data from a borehole core have been compiled to generate an updated range of thermal conductivities related to rock type and the lithostratigraphy. These indicate a total range in saturated vertical thermal conductivity of 1.67–3.24 W m−1 K−1, comprising 1.67–2.81 W m−1 K−1 for mudstones, 2.12–2.41 W m−1 K−1 for siltstones and 2.3–3.24 W m−1 K−1 for sandstones. These data are all from measurements on samples and there will be uncertainty when considering the thermal properties of the rock mass owing to micro- and macrostructural features. Geometric mean modelling of thermal conductivity based on mineralogy has overestimated the thermal conductivity. Correction factors for the modelled thermal conductivities have been calculated to allow a first estimate of MMG thermal conductivities when only mineralogical data are available. Measured thermal diffusivities from the borehole core were in the range of 0.63–3.07 × 10−6 m2 s−1 and are the first measured thermal diffusivities to be reported for the MMG.

Measurement of Thermal Conductivity of Apple at Different Moisture Contents

2011 ◽  
Vol 225-226 ◽  
pp. 556-559 ◽  
Author(s):  
Min Zhang ◽  
Jian Hua Chen ◽  
Zhen Hua Che ◽  
Hui Zhong Zhao ◽  
Jian Hua Lu
Keyword(s):  
Thermal Conductivity ◽  
Moisture Content ◽  
Engineering Application ◽  
Transient Heat Conduction ◽  
Linear Increase ◽  
Small Sample ◽  
Conduction Model ◽  
Food Engineering ◽  
Moisture Contents ◽  
Thermal Conductivities

Based on idealized non-steady state transient heat conduction model, the thermal conductivities of apple samples were determined at various moisture contents by using a specifically designed apparatus. The apparatus is rapidly, simply, accurately and only has relatively small sample requirement. Experimental data of thermal conductivities of apples showed a tendency of linear increase with the increase of moisture content of apple sample at the same temperature. An empirical correlation model for the thermal conductivity of apple as a function of moisture content was obtained. The developed model can be used to predict the thermal conductivity of apple satisfactorily in the entire range of moisture content. The results can be better contributed to the food engineering application.

Thermal Behavior of Unconsolidated Oil Sands

1974 ◽  
Vol 14 (05) ◽  
pp. 513-521 ◽  
Author(s):  
W.H. Somerton ◽  
J.A. Keese ◽  
S.L. Chu
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Physical Properties ◽  
Oil Sands ◽  
Thermal Recovery ◽  
Fluid System ◽  
Unconsolidated Sands ◽  
Saturated Sands ◽  
Wetting Fluid ◽  
Thermal Conductivities

ABSTRACT Thermal conductivities of unconsolidated oil sands have been measured and the results correlated with physical properties of the sand-fluid system. Saturation of the wetting fluid has a dominant effect on thermal conductivity values. Water-saturated sands were found to have thermal conductivities six to eight times greater than values for the same sand packs air saturated. For correlation purposes, the porosity of a sand pack is an adequate indicator of matrix structure. Other quantities needed to develop a satisfictory equation for predicting thermal conductivity are the conductivities of the wetting fluid and of the rock solids. The effects of changes in temperature on the thermal conductivity of unconsolidated oil sands are relatively small and can be evaluated with a simple linear equation. The effects of changes in pressure on the thermal conductivity of liquid-saturated unconsolidated sands are also small and for practical purposes can be ignored. Results of the present work are believed to have direct application to calculations relating to thermal processes in underground reservoirs. Core-analysis and well-log data can be used to evaluate the thermal properties of unconsolidated oil sands required for such calculations. INTRODUCTION The most successful thermal recovery operations are those that have been applied to relatively shallow producing formations consisting mostly of unconsolidated sands. Necessary in designing such projects is a knowledge of the thermal properties and behavior of the sand-fluid system under reservoir conditions of saturation, pressure, and temperature. A great deal of literature has been published on the thermal properties of granular materials, and several models and correlations for predicting thermal properties have been proposed.1–5 Unfortunately, most test data have been obtained for systems or conditions much different from those found in petroleum reservoirs. Most models or prediction equations do not cover ranges of variables of importance to subsurface applications and, in addition, often require knowledge of system parameters that normally are not readily available from common sources such as core analyses and well logs. The purpose of this work was to establish relationships between laboratory measurements of thermal properties and other more easily measurable properties of unconsolidated sands. Simple systems consisting of uniform-grain-size quartz sands saturated with single fluids were first studied. The work then progressed to more complex systems, including actual oilfield cores containing substantial portions of their original fluids. RELATIONSHIP OF THERMAL CONDUCTIVITY TO OTHER PHYSICAL PROPERTIES The thermal conductivity of fluid-saturated, unconsolidated sand is strongly dependent upon the saturation and thermal conductivity of the wetting phase fluid. Air- or gas-saturated sands characteristically have low thermal conductivities. This is because the contact areas between grains, through which heat must flow, are small. Introduction of a wetting-phase liquid greatly increases the thermal conductivity by increasing the effective grain contact area and thus enlarging the effective area through which heat can flow. Present experimental results show that the thermal conductivity of brine-saturated unconsolidated sands increases sixfold to eightfold over that of the same sand packs air saturated. This effect is considerably less pronounced in consolidated sandstones; Anand's data6 show a twofold to threefold increase between brine-saturated and air-saturated sand packs.

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