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Research Papers

Evaluation of Heat Transfer Effects on Turbocharger Performance

[+] Author and Article Information
Borislav Sirakov

Honeywell Turbo Technologies,
2525 W. 190th Street, TOR 36-2,
Torrance, CA 90504
e-mail: bobby.sirakov@honeywell.com

Michael Casey

Institute of Thermal Turbomachinery,
University of Stuttgart,
Pfaffenwaldring 6, D-70569, Stuttgart, Germany
e-mail: casey@itsm.uni-stuttgart.de

1Corresponding author.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received October 3, 2011; final manuscript received October 31, 2011; published online November 1, 2012. Editor: David Wisler.

J. Turbomach 135(2), 021011 (Nov 01, 2012) (10 pages) Paper No: TURBO-11-1218; doi: 10.1115/1.4006608 History: Received October 03, 2011; Revised October 31, 2011

Test data on several small turbochargers with different levels of heat transfer from the turbine to the compressor have been obtained through cooling of the turbocharger center housing and by testing in hot and cold test stands. This data identifies the strong effect of the heat transfer on the apparent efficiency of the compressor and turbine, particularly at low speeds and low mass flows. A simplified theory is used to explain the apparent effect of the heat transfer on the work input and efficiency. The results confirm that conventional performance maps underestimate the efficiency of the compressor stage and overestimate the efficiency of the turbine by as much as 20% points at low speeds. A correction procedure for this effect is defined which converts performance maps obtained with heat transfer to performance maps for adiabatic conditions (for both compressor and turbine) without any prior knowledge or measurement of the heat transfer. The practical significance of the results with regard to turbocharger performance and the relevance to a broader class of turbomachines is discussed.

Copyright © 2013 by ASME
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References

Figures

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Fig. 1

Typical efficiency variation at low speed from performance maps for a turbocharger compressor and a turbine

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Fig. 2

Schematic for the measurements made on the turbocharger gas stand used for this investigation

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Fig. 3

Sketch of water cooled center housing

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Fig. 4

Pressure rise characteristics (pressure rise coefficient versus normalized volume flow) of compressor 0 with and without cooling over a range of speeds. Solid lines indicate with cooling and dashed lines without cooling.

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Fig. 5

Compressor efficiency ratio characteristics of compressor 0 with and without cooling of the bearing housing. Solid lines indicate with cooling and dashed lines without cooling.

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Fig. 6

Turbine efficiency ratio characteristics of compressor 0 with and without cooling. Solid lines indicate with cooling and dashed lines without cooling.

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Fig. 7

Work coefficient and slip factor versus impeller outlet flow coefficient at different speeds for compressor 0 without cooling and with no correction for heat transfer effects

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Fig. 8

Work coefficient and slip factor versus impeller outlet flow coefficient at different speeds for compressor 0 without cooling but with correction for heat transfer effects

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Fig. 9

Work coefficient and slip factor versus impeller outlet flow coefficient at different speeds for compressor 0 with cooling and with correction for heat transfer effects

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Fig. 10

Efficiency ratio for compressor 0 with and without water cooling at different speeds corrected to adiabatic conditions. Solid lines indicate with cooling and dashed lines without cooling.

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Fig. 11

Corrected turbine efficiency ratios at different speeds. Solid lines indicate with cooling and dashed lines without cooling.

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Fig. 12

Work coefficient and slip factor versus impeller outlet flow coefficient at different speeds for compressor B/C tested up to high tip speeds

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Fig. 13

Work coefficient and slip factor versus impeller outlet flow coefficient at different speeds for compressor A tested on a hot gas-stand with correction for heat transfer effects

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Fig. 14

Work coefficient and slip factor versus impeller outlet flow coefficient for compressor A tested on a cold gas-stand at different speeds with correction for heat transfer effects

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Fig. 15

Work coefficient and slip factor versus impeller outlet flow coefficient for compressor D tested on a hot gas-stand at different speeds

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