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Heat and Mass Transfer

, 44:445 | Cite as

Unsteady fluid flow and heat transfer over a bank of flat tubes

  • N. Benarji
  • C. BalajiEmail author
  • S. P. Venkateshan
Original

Abstract

Transient numerical simulations of fluid flow and heat transfer over a bank of flat tubes have been carried for both in-line and staggered configurations for the following boundary conditions: (a) isothermal and (b) isoflux. The effect of Reynolds number, Prandtl number, length ratio, and the height ratio, on the Nusselt number, and the dimensionless pressure drop are elucidated. Correlations are proposed for both pressure drop and Nusselt number and optimum configurations have been determined.

Keywords

Nusselt Number Height Ratio Average Nusselt Number Total Heat Transfer Nusselt Number Increase 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

List of symbols

A

total area of all tubes, m2

At

are a of a single tube, m2

C

constant in the temperature boundary condition (Eq. 7)

Cp

specific heat, J/kg K

Da

transverse diameter of flat tube, m

Db

longitudinal diameter of flat tube, m

DH

hydraulic diameter, 2H, m

DP

dimensionless pressure drop, \({\frac{{P_{{\rm in}} - P_{{\rm out}}}}{{\rho U_{b}^{2}}}}\)

H

height of HEM, m

h

heat transfer coefficient for single HEM, W/m2 K

k

thermal conductivity, W/m K

L

length of HEM, m

m.

mass flow rate of the fluid across the tube bank, kg/s

Nu

Nusselt number, \({\frac{{h\,D_{H}}}{k}}\)

P

pressure, Pa

Pin

module inlet pressure, Pa

Pout

module outlet pressure, Pa

ΔP

pressure drop across the tube bank, Pa

Q

total heat transferred across the tube bank, W

q′′

constant heat flux on tube surface, W/m2

Re

Reynolds number, \({\frac{{U_{{\max}} \,D_{H}}}{\upsilon}}\)

ST

transverse pitch for tube bank, m

SL

longitudinal pitch for tube bank, m

T

temperature, K

Tb

bulk temperature at any cross section, K

Tb,m

average of the module inlet and module outlet temperatures, K

Tin

inlet temperature of the fluid, K

TW

constant temperature of tube surface, K

ΔT

temperature difference, K

t

time, s

U, V

horizontal and vertical velocities, m/s

Ub

bulk velocity at any cross section, m/s, \({\frac{1}{H}\,{\int\limits_0^H {U\,dy}}}\)

Uin

inlet velocity of the fluid, m/s

Umax

maximum velocity at the minimum cross section, m/s

X, Y

horizontal and vertical co-ordinates, m

Greek symbols

μ

dynamic viscosity, N·s/m2

ρ

density, kg/m3

ν

kinematic viscosity, m2/s

Subscripts

i

module number

Abbreviations

HEM

Heat exchanger module

IN

Inlet

MI

Module inlet

MO

Module outlet

OUT

Outlet

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Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  1. 1.Heat Transfer and Thermal Power Laboratory, Department of Mechanical EngineeringIndian Institute of Technology MadrasChennaiIndia

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