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TECHNICAL PAPERS: Gas Turbines: Heat Transfer

Effects of Manufacturing Tolerances on Regenerative Exchanger Number of Transfer Units and Entropy Generation

[+] Author and Article Information
Wei Shang

Department of Mechanical Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, S7N 5A9, Canadawes153@mail.usask.ca

Robert W. Besant

Department of Mechanical Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, S7N 5A9, Canada

J. Eng. Gas Turbines Power 128(3), 585-598 (Jul 28, 2005) (14 pages) doi:10.1115/1.2132380 History: Received November 08, 2004; Revised July 28, 2005

A prime concern with the design of ultra-compact heat exchangers is the impact on performance of flow channel variations due to flow channel hydraulic diameter variations caused by manufacturing tolerances. This paper uses analytical methods to show that as the standard deviation in flow channel sizes, caused by manufacturing tolerances in a rotary regenerative exchanger, is increased compared to the average flow channel diameter the effective number of transfer units decreases. Depending on the operating conditions, the entropy generation number either increases or decreases with increasing flow channel size variations. These findings extend previous findings that showed that flow channel variations cause lower pressure drops and effectiveness.

Copyright © 2006 by American Society of Mechanical Engineers
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References

Figures

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Figure 1

A typical regenerative exchanger rotor and six different flow channel geometries

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Figure 2

Schematic for counter-flow regenerative exchangers

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Figure 3

Pressure drop ratio, Δp∕Δp0, for regenerative exchangers with a matrix of (a) parallel surface flow channels as shown in Fig. 1 and symmetrical cylinder flow channels as shown in Figs.  1111 and (b) corrugated geometries as shown in Fig. 1 with random variations in flow channel sizes to one without versus σ∕D0

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Figure 4

Effectiveness ratio, ε∕ε0, for regenerative exchangers with a matrix of (a) parallel surface flow channels and symmetrical cylinder flow channels and (b) corrugated geometries for aspect ratio, η0=0.2, 0.5, 1.0, and 1.5, with random variations in flow channel sizes to one without versus σ∕D0

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Figure 5

Ntu ratio, Ntu∕Ntu0, for regenerative exchangers with a matrix of (a) parallel surface flow channels and (b) symmetrical cylinder flow channels with random variations in flow channel sizes to one without versus σ∕D0

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Figure 6

Ntu ratio, Ntu∕Ntu0, for regenerative exchangers with a matrix of corrugated flow channels with random variations in flow channel sizes to one without versus σ∕D0 for η0 at (a) 0.2 and (b) 0.5

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Figure 7

Entropy generation number due to thermal conductance versus non-dimensional temperature

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Figure 8

Entropy generation number due to thermal conductance effects versus effectiveness for various operating conditions

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Figure 9

Entropy generation number due to thermal conductance effects versus Ntu for various operating conditions

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Figure 10

Ratio of NS,T∕NS,p for regenerative exchangers with a matrix of parallel surface flow channels with random variations in flow channel sizes to one without versus σ∕D0 under ARI (a) summer cooling (θM=27.8) and (b) winter heating (θM=15.2) operating conditions

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Figure 11

Ratio of NS,T∕NS,p for regenerative exchangers with a matrix of symmetrical cylinder flow channels with random variations in flow channel sizes to one without versus σ∕D0 under ARI (a) summer cooling (θM=27.8) and (b) winter heating (θM=15.2) operating conditions

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Figure 12

Ratio of NS,T∕NS,p for regenerative exchangers with a matrix of corrugated flow channels with random variations in flow channel sizes to one without versus σ∕D0 for η0=0.2 under ARI (a) summer cooling (θM=27.8) and (b) winter heating (θM=15.2) operating conditions

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Figure 13

Ratio of NS,T∕NS,p for regenerative exchangers with a matrix of corrugated flow channels with random variations in flow channel sizes to one without versus σ∕D0 for η0=0.5 under ARI (a) summer cooling (θM=27.8) and (b) winter heating (θM=15.2) operating conditions

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Figure 14

Ratio of NS,T∕NS,p for regenerative exchangers with a matrix of parallel surface flow channels with random variations in flow channel sizes to one without versus σ∕D0 for two gas turbine operating conditions

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Figure 15

Ratio of NS,T∕NS,p for regenerative exchangers with a matrix of symmetrical cylinder flow channels with random variations in flow channel sizes to one without versus σ∕D0 for two gas turbine operating conditions

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Figure 16

Ratio of NS,T∕NS,p for regenerative exchangers with a matrix of corrugated flow channels with random variations in flow channel sizes to one without versus σ∕D0 for η0=0.2 for two gas turbine operating conditions

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Figure 17

Ratio of NS,T∕NS,p for regenerative exchangers with a matrix of corrugated flow channels with random variations in flow channel sizes to one without versus σ∕D0 for η0=0.5 for two gas turbine operating conditions

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Figure 18

Ratio of NS∕NS0 for regenerative exchangers with a matrix of parallel surface flow channels with random variations in flow channel sizes to one without versus σ∕D0 under ARI (a) summer cooling (θM=27.8) and (b) winter heating (θM=15.2) operating conditions

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Figure 19

Ratio of NS∕NS0 for regenerative exchangers with a matrix of symmetrical cylinder flow channels with random variations in flow channel sizes to one without versus σ∕D0 under ARI (a) summer cooling (θM=27.8) and (b) winter heating (θM=15.2) operating conditions

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Figure 20

Ratio of NS∕NS0 for regenerative exchangers with a matrix of corrugated flow channels with random variations in flow channel sizes to one without versus σ∕D0 for η0=0.2 under ARI (a) summer cooling (θM=27.8) and (b) winter heating (θM=15.2) operating conditions

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Figure 21

Ratio of NS∕NS0 for regenerative exchangers with a matrix of corrugated flow channels with random variations in flow channel sizes to one without versus σ∕D0 for η0=0.5 under ARI (a) summer cooling (θM=27.8) and (b) winter heating (θM=15.2) operating conditions

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Figure 22

Ratio of NS∕NS0 for regenerative exchangers with a matrix of parallel surface flow channels with random variations in flow channel sizes to one without versus σ∕D0 for two gas turbine operating conditions

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Figure 23

Ratio of NS∕NS0 for regenerative exchangers with a matrix of symmetrical cylinder flow channels with random variations in flow channel sizes to one without versus σ∕D0 for two gas turbine operating conditions

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Figure 24

Ratio of NS∕NS0 for regenerative exchangers with a matrix of corrugated flow channels with random variations in flow channel sizes to one without versus σ∕D0 for η0=0.2 for two gas turbine operating conditions

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Figure 25

Ratio of NS∕NS0 for regenerative exchangers with a matrix of corrugated flow channels with random variations in flow channel sizes to one without versus σ∕D0 for η0=0.5 for two gas turbine operating conditions

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