Thermal Contact Conductance Across Gold-Coated OFHC Copper Contacts in Different Media

2005 ◽  
Vol 127 (6) ◽  
pp. 657-659 ◽  
Author(s):  
Bapurao Kshirsagar, ◽  
Prashant Misra, ◽  
Nagaraju Jampana, and ◽  
M. V. Krishna Murthy
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Contact Pressure ◽  
Thermal Contact ◽  
High Conductivity ◽  
Thermal Contact Conductance ◽  
Ofhc Copper ◽  
Contact Conductance ◽  
Contact Pressures ◽  
Good Agreement

The thermal contact conductance studies across gold-coated oxygen-free high-conductivity copper contacts have been conducted at different contact pressures in vacuum, nitrogen, and helium environments. It is observed that the thermal contact conductance increases not only with the increase in contact pressure but also with the increase in thermal conductivity of interstitial medium. The experimental data are found to be in good agreement with the literature.

Effect of Metallic Coatings on the Thermal Contact Conductance of Turned Surfaces

1990 ◽  
Vol 112 (4) ◽  
pp. 864-871 ◽  
Author(s):  
T. K. Kang ◽  
G. P. Peterson ◽  
L. S. Fletcher
Keyword(s):  
Experimental Data ◽  
Thermal Contact ◽  
Coating Material ◽  
Thermal Contact Conductance ◽  
Enhancement Effect ◽  
Metallic Coatings ◽  
Coating Materials ◽  
Contact Conductance ◽  
Significant Parameter ◽  
Contact Pressures

An experimental investigation was conducted to determine the degree to which the thermal contact conductance at the interface of contacting Aluminum 6061 T6 surfaces could be enhanced through the use of vapor-deposited metallic coatings. Three different coating materials (lead, tin, and indium) were evaluated using four different thicknesses for each coating material. The results verified the existence of an optimum coating thickness, shown to be in the range of 2.0 to 3.0 μm for indium, 1.5 to 2.5 μm for lead, and 0.2 to 0.5 μm for tin. The enhancement factors for thermal contact conductance were found to be on the order of 700, 400, and 50 percent, respectively. Based upon the experimental data, the hardness of the coating materials appears to be the most significant parameter in ranking the substrate and coating material combinations; however, additional experimental data are needed to substantiate this hypothesis. Finally, it was apparent that the thermal contact conductance enhancement effect was greatest at low contact pressures and decreased significantly with increases in the contact pressure.

Measurement of the Thermal Contact Conductance and Thermal Conductivity of Anodized Aluminum Coatings

1990 ◽  
Vol 112 (3) ◽  
pp. 579-585 ◽  
Author(s):  
G. P. Peterson ◽  
L. S. Fletcher
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Coating Thickness ◽  
Thermal Contact ◽  
Thermal Contact Conductance ◽  
Aluminum Surface ◽  
Anodized Aluminum ◽  
Contact Conductance ◽  
Surface Measurements

An experimental investigation was conducted to determine the thermal contact conductance and effective thermal conductivity of anodized coatings. One chemically polished Aluminum 6061-T6 test specimen and seven specimens with anodized coatings varying in thickness from 60.9 μm to 163.8 μm were tested while in contact with a single unanodized aluminum surface. Measurements of the overall joint conductance, composed of the thermal contact conductance between the anodized coating and the bare aluminum surface and the bulk conductance of the coating material, indicated that the overall joint conductance decreased with increasing thickness of the anodized coating and increased with increasing interfacial load. Using the experimental data, a dimensionless expression was developed that related the overall joint conductance to the coating thickness, the surface roughness, the interfacial pressure, and the properties of the aluminum substrate. By subtracting the thermal contact conductance from the measured overall joint conductance, estimations of the effective thermal conductivity of the anodized coating as a function of pressure were obtained for each of the seven anodized specimens. At an extrapolated pressure of zero, the effective thermal conductivity was found to be approximately 0.02 W/m-K. In addition to this extrapolated value, a single expression for predicting the effective thermal conductivity as a function of both the interface pressure and the anodized coating thickness was developed and shown to be within ±5 percent of the experimental data over a pressure range of 0 to 14 MPa.

Influence of Contact Pressure on the Thermal Contact Conductance of Layered AA3003 Aluminium

2020 ◽  
Vol 15 ◽  
Keyword(s):  
Thermal Conductivity ◽  
Contact Pressure ◽  
Thermal Contact ◽  
Thermal Conductance ◽  
Thermal Contact Conductance ◽  
Contact Conductance ◽  
Interface Thermal Resistance ◽  
Measurement Results ◽  
Semi Empirical ◽  
The Relationship

For the optimization of the annealing process of aluminium coils, simulation of the process is often performed. To simulate the process with higher accuracy, reliable input parameters are required and the thermal conductivity (thermal contact conductance) is one of them. In the present study, the thermal conductivity and thermal contact conductance of AA3003 alloy sheets were measured by a steady state comparative longitudinal heat flow method at different contact pressure. To evaluate the thermal conductance at the interface, thermal resistance network model' was applied. In addition, the surface roughness of the sheets was also investigated. Based on the measurement results, the semi-empirical equation for the relationship between thermal contact conductance and contact pressure was obtained

An Experimental Study to Show the Effect of Thermal Stress on Thermal Contact Conductance at Sub-megapascal Contact Pressures

2010 ◽  
Vol 132 (9) ◽  
Author(s):  
Prashant Misra ◽  
J. Nagaraju
Keyword(s):  
Thermal Stress ◽  
Contact Pressure ◽  
Thermal Stresses ◽  
Thermal Contact ◽  
Experimental Studies ◽  
Thermal Contact Conductance ◽  
Large Temperature ◽  
Contact Conductance ◽  
Closed Contact ◽  
Contact Pressures

Experimental studies are presented to show the effect of thermal stresses on thermal contact conductance (TCC) at low contact pressures. It is observed that in a closed contact assembly, contact pressure acting on the interface changes with the changing temperature of contact members. This change in contact pressure consequently causes variations in the TCC of the junction. A relationship between temperature change and the corresponding magnitude of developed thermal stress in a contact assembly is determined experimentally. Inclusion of a term called temperature dependent load correction factor is suggested in the theoretical model for TCC to make it capable of predicting TCC values more accurately in contact assemblies that experience large temperature fluctuations.

A Model for Predicting Temperature of Electrofusion Joints for Polyethylene Pipes

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
Jianfeng Shi ◽  
Jinyang Zheng ◽  
Weican Guo ◽  
Ping Xu ◽  
Yongquan Qin ◽  
...  
Keyword(s):  
Thermal Contact ◽  
Power Input ◽  
Ultrasonic Test ◽  
Thermal Contact Conductance ◽  
Transfer Model ◽  
Contact Conductance ◽  
One Dimensional ◽  
Polyethylene Pipes ◽  
Heating Wire ◽  
Good Agreement

With the increasing application of electrofusion (EF) welding in connecting polyethylene (PE) pipes for gas distribution, more effort has been invested to ensure the safety of the pipeline systems. The objective of this paper is to investigate and understand the temperature distribution during EF welding. A one-dimensional transient heat-transfer model was proposed, taking the variation in the rate of power input, the phase transition of PE, and the thermal contact conductance between heating wire and PE into consideration. Then, experiments were designed to verify the power input and the temperature. The measured values of the power input were shown to be in good agreement with the analytical results. Based on ultrasonic test (UT), a new “Eigen-line” method was presented, which overcomes the difficulties found in the thermocouples’ temperature measurements. The results demonstrate good agreements between prediction and experiment. Finally, based on the presented model, a detailed parametric study was carried out to investigate the influences of the variation in the power input, the physical properties of PE, and the thermal contact conductance between heating wire and surrounding PE.

A New Method for Measuring Thermal Contact Conductance: Experimental Technique and Results

2008 ◽  
Author(s):  
Simon Woodland ◽  
Andrew D. Crocombe ◽  
John W. Chew ◽  
Stephen J. Mills
Keyword(s):  
Thermal Contact ◽  
New Method ◽  
Thermal Contact Conductance ◽  
Metal Working ◽  
Loading History ◽  
Test Rig ◽  
Contact Conductance ◽  
Pressure Surface ◽  
Surface Flatness ◽  
Good Agreement

Thermal contact conductance (TCC) is used to characterise heat transfer across interfaces in contact. It is important in thermal modelling of turbomachinery components and finds many other applications in the aerospace, microelectronic, automotive and metal working industries. A new method for measuring TCC is described and demonstrated. A test rig is formed from an instrumented split tube with washers in-between and loading applied in controlled conditions. The experimental method and data analysis is described, and the effect on thermal contact conductance of parameters such as contact pressure, surface roughness, surface flatness and loading history is investigated. The results of these tests are compared to those in the available literature and good agreement of trends is found. However, the tests conducted to measure the effect of load cycling on TCC have found that the TCC continues to increase beyond 20 or so load cycles, contrary to some results in the literature.

Study on evaluation method of tube—fin thermal contact conductance

2010 ◽  
Vol 225 (2) ◽  
pp. 390-396
Author(s):  
D Tang ◽  
D Li ◽  
Y Peng ◽  
Z Du
Keyword(s):  
Contact Pressure ◽  
Evaluation Method ◽  
Thermal Contact ◽  
Element Model ◽  
Thermal Contact Conductance ◽  
Forming Process ◽  
Contact Conductance ◽  
Die Geometry ◽  
Novel Method ◽  
Tube Expansion

The thermal contact conductance (TCC) is one of the principal parameter in heat transfer mechanism of tube—fin heat exchangers. Because of the difficulties in experimental measurements, the tube—fin TCC has not been focused deeply. This article presents a novel method in evaluating the TCC of tube—fin heatexchanger. First, the tube—fin contact status is investigated with a finite-element model of tube expansion process. Distribution of contact pressure along the tube—fin interface is obtained from the simulation results. Then, experiments are carried out for the relationship between the contact pressure and the TCC. Combining the experiment result with the contact pressure distribution, the tube—fin TCC can be evaluated. Based on the method, effect of processing factors of the expansion forming process, such as expanding ratio and die geometry, are examined.

Influence of Temperature Distribution on Tighten Force in Tie-Bolt Fastened Rotor With Considering Thermal Contact Conductance

2015 ◽  
Author(s):  
He Peng ◽  
Ning Xu ◽  
Zhansheng Liu
Keyword(s):  
Surface Roughness ◽  
Thermal Expansion ◽  
Temperature Distribution ◽  
Contact Pressure ◽  
Thermal Contact ◽  
Thermal Contact Conductance ◽  
Axial Position ◽  
Contact Conductance ◽  
Pressure Surface ◽  
Axial Temperature

Tighten force has much influence on tie-bolt fastened rotor dynamics. Temperature distribution in tie-bolt fastened rotor results in thermal expansion of rotor and rods. The difference of thermal expansion between rotor and rods causes the variation of bolt load. With considering the thermal contact conductance, the thermal model of tie-bolt fastened rotor was established by finite element method and the axial temperature distribution was obtained. The influences of surface roughness, nominal contact pressure and axial position of contact on axial temperature distribution were analysed. Based on temperature distribution in the tie-bolt fastened rotor, the variation of tighten force was investigated. Results show that nominal contact pressure, surface roughness and axial contact arrange have different influences on the variation of tighten force with temperature.

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