In this paper developing laminar fluid flow and heat transfer performance in toroidal and helical coiled tube heat exchanger systems with coil-to-tube radius ratios (5 to 45) and small helical pitch are investigated using appropriate numerical modeling techniques available in the CFD package (Fluent v6.2). Base CFD models were primarily developed, optimized and compared with available published friction factor and heat transfer data and correlations for the toroidal and helical coil systems. With the proven CFD modeling technique and the results obtained, the analysis was extended to the coil-to-tube radius ratios of interest and to the investigation of the effect of thermo-physical properties of working fluids on the system thermal performance. The CFD models employ variable thermo-physical properties in the analysis of uniform wall temperature heating and cooling of common working fluids such as air and water. Defining appropriate dimensionless variables to describe the developing and redeveloping hydrodynamic and thermal flow for coiled tube systems, the variations of friction factor and local Nusselt number along the coil are investigated. It has been shown that in addition to the common affecting parameters, i.e. the coil-to-tube radius ratio and the Dean and Prandtl numbers, the heat transfer performance also depends upon the interactions (expansion and suppression) between the viscous and thermal boundary layers due to secondary flows caused by the centrifugal and torsional forces inherent in coiled tube systems. Upon investigation of the variations of the local dimensionless velocity and temperature along the coil length, it was found that for both heating and cooling conditions, fully-developed hydrodynamic and thermal conditions are not established in the coiled-tube system for the geometric constraints and system boundary and operating conditions used in this work. The case studies performed in this paper indicated approximately 20-30% higher for heating of water (20-30% lower for cooling of air and water) than values of heat transfer coefficients obtained from the reported correlations. The results obtained in this work can be used to correct/adjust the flow and thermal performance used in the design of toroidal and helical coiled tube systems.

1.
Dean
W. R.
,
1927
Note on the Motion of Fluid in a Curved Pipe
,”
Philosophical Magazine and Journal of Science, Series 7
, v
4
, n
20
pp.
208
223
.
2.
Dean
W. R.
,
1928
, “
The Stream-line Motion of Fluid in a Curved Pipe
,”
Philosophical Magazine and Journal of Science, Series 7
, v
5
, n
30
(April, 1928), pp
673
695
.
3.
Ito, H., 1959, “Friction Factors for Turbulent Flow in Curved Pipes,” Transactions of the ASME, Journal of Basic Engineering, June, 1959, pp 123-134.
4.
Mori
Yasuo
, and
Nakayama
Waturu
,
1965
, “
Study on Forced Convective Heat Transfer in Curved Pipes (1st Report, Laminar Region)
,”
International Journal of Heat and Mass Transfer
, v
8
, p
67
82
.
5.
Schmidt
Eckehard F.
,
1967
, “
Wa¨rmeu¨bergang und Druckverlust in Rohrschlagen
,”
Chemie Ingenieur Technik
, v
13
, n
39
(10 July, 1967), pp
781
832
.
6.
Manlapaz
Romeo L.
, and
Churchill
Stuart W.
,
1980
, “
Fully Developed Laminar Flow in a Helically Coiled Tube of Finite Pitch
,”
Chemical Engineering Communication
, v
7
, pp
57
78
.
7.
Manlapaz
Romeo L.
, and
Churchill
Stuart W.
,
1981
, “
Fully Developed Laminar From a Helical Coil
,”
Chemical Engineering Communication
, v
9
, pp
185
200
.
8.
Bowman, Anthony J., and Park, Hyunjae, 2003, “Numerical Investigation of Generalized Correlations for Turbulent Flow Pressure Drop and Heat Transfer Applied in Helically Coiled Tube Systems.,” 2003 ASME International Mechanical Engineering Conference & Exposition, Proceedings of IMECE 2003, Washington, D. C., November 15-21, 2003, IMECE 2003-42672.
9.
Bowman, Anthony J., and Park, Hyunjae, 2004, “Investigation and Development of Proposed General Pressure Drop and Heat Transfer Correlations for Laminar Flow in a Toroidal Coiled Tube System,” 2004 ASME International Mechanical Engineering Conference & Exposition, Proceedings of IMECE 2004, Anaheim, CA, November 13-19, 2004, IMECE 2004-59872.
10.
Bowman, Anthony J., and Park, Hyunjae, 2004, “CFD Study on Laminar Flow Pressure Drop and Heat Transfer Characteristics in Toroidal and Spiral Coil Systems,” 2004 ASME International Mechanical Engineering Conference & Exposition, Proceedings of IMECE 2004, Anaheim, CA, November 13-19, 2004, IMECE 2004-59872.
11.
Park, Hyunjae, and Bowman, Anthony J., 2005, “Governing Equations Used in Coiled Tube Systems-Part I: Development of Standard/General Forms,”0 9th Joint AIAA/ASME Thermophysics and Heat Transfer Conference, San Francisco, CA, June 5-8, 2006 (in press).
12.
Park, Hyunjae, and Bowman, Anthony J., 2005, “Governing Equations Used in Coiled Tube Systems-Part II: Order-of-Magnitude Analysis of Spiral Coil Systems,” 9th Joint AIAA/ASME Thermophysics and Heat Transfer Conference, San Francisco, CA, June 5-8, 2006 (in press).
13.
Hausen
H.
,
1943
,
Z. VDI Beih. Verfahrenstech
.,
4
,
91
91
, [1943].
14.
Tannehill, J. C., Anderson, D. A., and Plechter, R. H., 1997 “Computational Fluid Mechanics and Heat Transfer,” 2nd ed., Taylor & Francis, Washington, D. C.
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