Summary
The asymptotic solution of laminar convective heat transfer in the entrance region of a circular conduit where velocity and temperature profiles are developing simultaneously, is obtained for fluids with high Prandtl numbers. Numerical values of local and average Nusselt numbers as functions of Pr and dimensionless longitudinal distances have been evaluated and presented in graphical forms.
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Abbreviations
- A 0, A 1 ... A k :
-
coefficients defined by (40)
- B 0, B 1 ... B k :
-
coefficients defined by (39)
- C p :
-
heat capacity of fluid
- I n (x) = i −n J n (ix):
-
where J n is the n th order Bessel function
- k :
-
thermal conductivity of fluid
- Nu z :
-
local Nusselt number defined by (41)
- Nu av :
-
average Nusselt number defined by (44)
- P :
-
pressure
- Pr :
-
Prandtl number of fluid defined as C p μ/k
- q :
-
heat flux
- Re :
-
Reynold number, defined as ŪPR/μ
- R :
-
radius of pipe
- r :
-
radial distance
- r + :
-
dimensionless radial distance defined by (8)
- T :
-
temperature of fluid
- T 0 :
-
initial temperature of fluid
- T w :
-
wall temperature
- T + :
-
dimensionless temperature defined by (11)
- T +0 , T +1 , ... T /+ k ...:
-
functions related to T + by (22).
- u :
-
dimensionless variables defined by (20)
- v r :
-
radial component of velocity
- v z :
-
z-component of velocity
- v + :
-
dimensionless velocity defined by (10)
- y + :
-
dimensionless distance defined by (8)
- X :
-
dimensionless parameter defined by (38)
- z :
-
longitudinal distance
- z + :
-
dimensionless longitudinal distance defined by (9)
- α :
-
thermal diffusivity
- β :
-
dimensionless parameter defined by (12)
- γ :
-
a parameter appearing in (46)
- Γ(x):
-
gamma function
- ρ :
-
density
- η :
-
dimensionless variable defined by (28)
- θ :
-
parameter defined by (19)
- ζ :
-
dimensionless variable defined by (32)
- μ :
-
viscosity of fluid
- ν :
-
kinematic viscosity of fluid
References
Kays, W. M., Trans. A.S.M.E. 77 (1955) 1265.
Langhaar, H. L., J. Appl. Mech. 64 (1942) A-55.
Goldberg, P., M.S. Thesis, Mech. Eng. Dept., M.I.T., 1958. Also see Rosenhow, W. M. and H. Y. Choi, Heat Mass and Momentum Transfer, P. 165, Prentice-Hall Inc., 1961.
Sparrow, E. M., N.A.C.A., TN 3331, 1955.
Yau, J. and C. Tien, Can. J. Chem. Eng. 41 (1963) 139.
Acrivos, A., Phys. Fluids 3 (1960) 657.
Acrivos, A., Chem. Eng. Sci. 17 (1962) 457.
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Tien, C., Pawelek, R.A. Laminar flow heat transfer in the entrance region of circular tubes. Appl. sci. Res. 13, 317–331 (1964). https://doi.org/10.1007/BF00382058
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DOI: https://doi.org/10.1007/BF00382058