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.

Issue Section:
Gas Turbines: Heat Transfer
Keywords:
heat exchangers, channel flow, tolerance analysis, heat transfer, entropy
Topics:
Entropy, Flow (Dynamics), Pressure drop, Manufacturing, Symmetry (Physics)
1.
Shang
,
W.
, and
Besant
,
R. W.
, 2004, “
Measurement of Pore Size Variation and Its Effect on Energy Wheel Performance
,”
ASHRAE Trans.
0001-2505,
110
(
1
), pp.
410
–
421
.
2.
Shang
,
W.
, and
Besant
,
R. W.
, 2005, “
Effects of Pore Size Variations on Regenerative Wheel Performance
,”
ASME J. Eng. Gas Turbines Power
0742-4795,
127
, pp.
121
–
135
.
Crossref
Search ADS
 
3.
Kays
,
W. M.
, and
London
,
A. L.
, 1984,
Compact Heat Exchangers
,
McGraw-Hill
, New York, pp.
19
–
33
.
4.
ASHRAE
, 1991,
ANSI/ASHRAE Standard 84–1991R: Method of Testing Air-to-Air Heat Exchangers
, American Society of Heating,
Refrigerating and Air-Conditioning Engineers, Inc.
, Atlanta.
5.
Simonson
,
C. J.
, and
Besant
,
R. W.
, 1999, “
Energy Wheel Effectiveness, Part I: Development of Dimensionless Groups; Part II: Correlations
,”
Int. J. Heat Mass Transfer
0017-9310,
42
(
12
), pp.
2161
–
2185
.
Crossref
Search ADS
 
6.
Lambertson
,
T. J.
, 1958, “
Performance Factors of a Periodic-Flow Heat Exchanger
,”
Trans. ASME
0097-6822,
80
, pp.
586
–
592
.
7.
Bejan
,
A.
, 1982,
Entropy Generation through Heat and Fluid Flow
,
Wiley
, New York.
8.
Bejan
,
A.
, 1996, “
Entropy Generation Minimization: The New Thermodynamics of Finite-Size Devices and Finite-Time Processes
,”
J. Appl. Phys.
0021-8979,
79
, pp.
1191
–
1218
.
Crossref
Search ADS
 
9.
Bejan
,
A.
, 1997,
Advanced Engineering Thermodynamics
,
Wiley
, New York.
10.
Dellenback
,
P. A.
, 2002, “
Improved Gas Turbine Efficiency Through Alternative Regenerator Configuration
,”
ASME J. Eng. Gas Turbines Power
0742-4795,
124
, pp.
441
–
446
.
Crossref
Search ADS
 
11.
ARI
, 2001,
ARI Standard 1060: Rating Air-to-Air Energy Recovery Ventilation Equipment
,
Air-Conditioning & Refrigeration Institute
, Arlington, VA.
Copyright © 2006
 by American Society of Mechanical Engineers
You do not currently have access to this content.