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Research Papers

Experimental Characterization and Modeling of Thermal Contact Resistance of Electric Machine Stator-to-Cooling Jacket Interface Under Interference Fit Loading

[+] Author and Article Information
J. Emily Cousineau

National Renewable Energy Laboratory (NREL),
15013 Denver West Parkway,
Golden, CO 80401
e-mail: Emily.Cousineau@nrel.gov

Kevin Bennion

National Renewable Energy Laboratory (NREL),
15013 Denver West Parkway,
Golden, CO 80401

Victor Chieduko

UQM Technologies, Inc.,
4120 Specialty Pl.,
Longmont, CO 80504

Rajiv Lall, Alan Gilbert

UQM Technologies, Inc.,
4120 Specialty Pl.,
Longmont, CO 80504

1Corresponding author.

Contributed by the Heat Transfer Division of ASME for publication in the JOURNAL OF THERMAL SCIENCE AND ENGINEERING APPLICATIONS. Manuscript received July 6, 2017; final manuscript received January 15, 2018; published online May 8, 2018. Assoc. Editor: Steve Q. Cai. The United States Government retains, and by accepting the article for publication, the publisher acknowledges that the United States Government retains, a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for United States government purposes.

J. Thermal Sci. Eng. Appl 10(4), 041016 (May 08, 2018) (7 pages) Paper No: TSEA-17-1239; doi: 10.1115/1.4039459 History: Received July 06, 2017; Revised January 15, 2018

Cooling of electric machines is a key to increasing power density and improving reliability. This paper focuses on the design of a machine using a cooling jacket wrapped around the stator. The thermal contact resistance (TCR) between the electric machine stator and cooling jacket is a significant factor in overall performance and is not well characterized. This interface is typically an interference fit subject to compressive pressure exceeding 5 MPa. An experimental investigation of this interface was carried out using a thermal transmittance setup using pressures between 5 and 10 MPa. The results were compared to currently available models for contact resistance, and one model was adapted for prediction of TCR in future motor designs.

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References

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Figures

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Fig. 1

Electric machine cross section highlighting stator-to-case contact

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Fig. 2

Top: machine stator surface. Bottom: case interior surface.

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Fig. 3

High-pressure thermal transmittance setup showing cutaway view of sample stabilizing rig

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Fig. 4

Edge views of lamination materials. The microscope stage is labeled for clarity.

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Fig. 5

Ten-mm square sample area surface profile of the contact plate

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Fig. 6

Thermal resistance as a function of lamination coupon thickness

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Fig. 7

Comparison of contact plate surface finish effect on TCR

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Fig. 8

Total thermal resistance measurements for M15 29-gauge coupons at 5.52 MPa with extrapolation to 0 lamination coupon thickness

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Fig. 9

Top: stator-to-case TCR results. Bottom: lamination effective thermal conductivity results. Error bars represent the 95% confidence interval.

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Fig. 10

Top: Comparison of TCR model to M15 29-gauge data. Bottom: comparison of TCR model to JFE (0.2 mm) data. Root mean square surface roughness of the contacting surfaces used in the model is noted on the plot. Error bars indicate 95% confidence interval for the data.

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