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.

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

2011 ◽  
Vol 133 (7) ◽  
Author(s):  
Simon Woodland ◽  
Andrew D. Crocombe ◽  
John W. Chew ◽  
Stephen J. Mills
Keyword(s):  
Thermal Contact ◽  
New Method ◽  
Thermal Contact Conductance ◽  
Experimental Program ◽  
Material Strength ◽  
Metal Working ◽  
Test Rig ◽  
Contact Conductance ◽  
Material Parameters ◽  
Pressure Surface

Thermal contact conductance (TCC) is used to characterize heat transfer across interfaces in contact. It is important in thermal modeling of turbomachinery components and finds many other applications in the aerospace, microelectronic, automotive and metal working industries. In this paper, a new method for measuring TCC is described and demonstrated. A test rig is formed from an instrumented split tube with in-line washers and loading applied under controlled conditions. The experimental method and data analysis are described, and the effects on thermal contact conductance of important parameters such as the contact pressure, surface roughness, temperature, thermal conductivity, and material strength are investigated. Normalization of the TCC measured in the experimental program was carried out using appropriate surface and material parameters. The results of this normalization are used to compare the normalized experimental results with various models from the literature.

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.

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.

A new method of measuring thermal contact conductance

2004 ◽  
Vol 145 (2) ◽  
pp. 207-214 ◽  
Author(s):  
M Rosochowska ◽  
K Chodnikiewicz ◽  
R Balendra
Keyword(s):  
Thermal Contact ◽  
New Method ◽  
Thermal Contact Conductance ◽  
Contact Conductance

Measurement of Thermal Contact Conductance of a Heat Shield for Gas Turbine Combustors in a Realistic Test Rig Set-Up

2012 ◽  
Author(s):  
B. Facchini ◽  
F. Simonetti ◽  
L. Tarchi ◽  
R. Abram ◽  
M. Maritano
Keyword(s):  
Gas Turbine ◽  
Thermal Contact ◽  
Operating Conditions ◽  
Heat Shield ◽  
Ceramic Fiber ◽  
Thermal Contact Conductance ◽  
Test Rig ◽  
Contact Conductance ◽  
Experimental Campaign ◽  
Set Up

This paper presents the results of the experimental campaign on the measurement of thermal contact conductance (TCC) in a realistic test rig replicating the contact between the ceramic heat shield and the liner for an ANSALDO Energia s.p.a. heavy-duty gas turbine. The designed test rig is made up of a single sector consisting of a combustor ceramic brick and a liner sector with a non-rigid ceramic fiber textile insulating layer in between, to better replicate the operating conditions of the combustor components. The experimental campaign was carried out with a steady-state technique applying an uniform thermal load on the heat shield surface. The effect of brick-holders, that in the actual combustor anchor the bricks on the liner walls, was replicated with static loads. The liner sector was tested without the brick-holder grooves first and afterwards their effect was assessed in the same test conditions; the test campaign also aimed at measuring the load cycling effect on TCC. Validation of the measured TCC was then performed with a finite element code to compare the predicted temperature profiles with the measured ones.

Fractal Model for Thermal Contact Conductance

2008 ◽  
Vol 130 (10) ◽  
Author(s):  
Mingqing Zou ◽  
Boming Yu ◽  
Jianchao Cai ◽  
Peng Xu
Keyword(s):  
Random Number ◽  
Rough Surfaces ◽  
Thermal Contact ◽  
Fractal Model ◽  
Thermal Contact Conductance ◽  
Bulk Resistance ◽  
Contact Conductance ◽  
Proposed Model ◽  
Fractal Parameters ◽  
Good Agreement

A random number model based on fractal geometry theory is developed to calculate the thermal contact conductance (TCC) of two rough surfaces in contact. This study is carried out by geometrical and mechanical investigations. The present study reveals that the fractal parameters D and G have important effects on TCC. The predictions by the proposed model are compared with existing experimental data, and good agreement is observed by fitting parameters D and G. The results show that the effect of the bulk resistance on TCC, which is often neglected in existing models, should not be neglected for the relatively larger G and D. The main advantage of this model is the randomization of roughness distributions on rough surfaces. The present results also show a better agreement with the practical situation than the results of other models. The proposed technique may have the potential in prediction of other phenomena such as friction, radiation, wear and lubrication on rough surfaces.

On the Enhancement of the Thermal Contact Conductance: Effect of Loading History

1999 ◽  
Vol 122 (1) ◽  
pp. 46-49 ◽  
Author(s):  
Y. Z. Li ◽  
C. V. Madhusudana ◽  
E. Leonardi
Keyword(s):  
Heat Flow ◽  
Contact Resistance ◽  
Experimental Work ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Cost Effective ◽  
Thermal Contact Conductance ◽  
Loading History ◽  
Contact Conductance ◽  
Resistance To Heat

A resistance to heat flow exists at the junction of two surfaces. It has long been recognized that there exists a hysteresis effect, that is, the value of thermal contact resistance in the unloading process is less than that in the loading process at the same load. However, little work has been done in utilizing this phenomenon to enhance the thermal contact conductance. The present experimental work investigated the effect of loading history; in particular the number of load cycles and overloading pressure, on the thermal contact conductance. It was found that the value of the thermal contact conductance might be enhanced by up to 51 percent. A cost-effective way of enhancing the contact conductance is suggested. [S0022-1481(00)01601-7]

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.

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