Forced Convection of Outer Pipe Surface | Online Calculator

Convection Film Coefficients Calculators

Convection Film Coefficient of an External Pipe Surface

The heat transfer of the pipe inner surface is calculated using the similarity equation:

Nuf = 0.5×Ref0.5×Pr0.38 - at laminar flow;

Nuf = 0.25×Ref0.6×Pr0.43 - at turbulent flow;

Rel - Reynolds number, Pr - Prandtl number.

εψ - coefficient, depending on attack angle of the flow.

In this calculation, the process of heat transfer from the pipe outer surface of diameter D is considered. The surface is in contact with a fluid flow with dynamic viscosity μ, density ρ, thermal conductivity λ and specific heat Cp. The flow crosses the pipe at an angle ψ with an average velocity W.

As a result of calculations, the convective film coefficient α of pipe outer surface is determined. In addition, similarity criteria for a given design case are determined, including Reynolds number Re, Prandtl number Pr, Peclet number Pe and Nusselt number Nu.

Convection Film Coefficient of the external Pipe Surface
calculation of Convection Film Coefficient of the external Pipe Surface

INITIAL DATA

D - Pipe outer diameter;

w - Flow rate;

ψ - Angle between the pipe and flow direction;

μ - Dynamic fluid viscosity;

ρ - Fluid density;

λ - Thermal conductivity coefficient of fluid;

Cp - Specific heat of fluid.

RESULTS DATA

α - Convection film coefficient of pipe surface.

Re - Reynolds number.

Pr - Prandtl number.

Pe - Peclet number.

Nu - Nusselt number.

Diameter (D)

Flow rate (w)

Attack angle (ψ)

Dynamic viscosity (μ)

Density (ρ)

Thermal conductivity (λ)

Specific heat (Сp)

Film coefficient (α)

Reynolds number (Re)

Prandtl number (Pr)

Peclet number (Pe)

Nusselt number (Nu)

BASIC FORMULAS

Reynolds number:

Re = ρ*w*D / μ;

Peclet number:

Pe = Сp*ρ*w*D / λ;

Prandtl number:

Pr = Pe / Re;

Nusselt number:

Nu = 0.5*Re0.5*Pr0.38*εψ - at laminar flow;
Nu = 0.25*Re0.6*Pr0.43*εψ - at turbulent flow;

εψ - coefficient taking into account the angle between the pipe and the direction of flow;

Convection film coefficient:

α = Nu*λ / D.

INITIAL DATA

D - Outer diameter of pipe;

w - Flow rate;

ψ - Angle between the pipe and flow direction;

μ - Fluid dynamic viscosity;

ρ - Fluid density;

λ - Thermal conductivity coefficient of fluid;

Cp - Specific heat of fluid.

RESULTS DATA

α - Convection film coefficient of pipe surface.

Re - Reynolds number.

Pr - Prandtl number.

Pe - Peclet number.

Nu - Nusselt number.

FLUID PROPERTIES

Fluid properties at 20ºC (68 ºF)

Fluid

Density

Kg/m³

(lb/ft³)

Dynamic viscosity

Pa*s

(lb*s/ft²)

Volumetric

expansion

1/ºC

(1/ºF)

Thermal

conductivity

W/m*ºC

(W/in*ºF)

Specific heat

J/kg*ºC

(J/lb*ºF)

Water

998

(62.3)

0.001

(0.0000209)

0.00021

(0.00016)

0.599

(0.084)

4182

(1053)

Air

1.205

(0.075)

0.000018

(0.000000377)

0.00365

(0.00202)

0.0259

(0.00036)

1005

(253)

Water vapor

0.01

(0.00063)

0.0000096

(0.0000002)

0.00365

(0.00202)

0.0178

(0.00025)

1859

(468)

Engine Oil SAE

15W-40

879

(54.9)

0.287

(0.006)

0.00655

(0.0036)

0.134

(0.00190)

2039

(513)

Fluid properties at 40ºC (104 ºF)

Fluid

Density

Kg/m³

(lb/ft³)

Dynamic viscosity

Pa*s

(lb*s/ft²)

Volumetric

expansion

1/ºC

(1/ºF)

Thermal

conductivity

W/m*ºC

(W/in*ºF)

Specific heat

J/kg*ºC

(J/lb*ºF)

Water

992

(62)

0.00065

(0.0000135)

0.00021

(0.00016)

0.635

(0.0090)

4170

(1050)

Air

1.128

(0.07)

0.000019

(0.000000397)

0.00365

(0.00202)

0.0276

(0.00039)

1005

(253)

Water vapor

0.05

(0.0031)

0.0000104

(0.000000217)

0.00365

(0.00202)

0.0195

(0.000275)

1860

(468)

Engine Oil SAE

15W-40

866

(54.1)

0.091

(0.0019)

0.00655

(0.0036)

0.131

(0.00184)

2106

(530)

Fluid properties at 60ºC (140 ºF)

Fluid

Density

Kg/m³

(lb/ft³)

Dynamic viscosity

Pa*s

(lb*s/ft²)

Volumetric

expansion

1/ºC

(1/ºF)

Thermal

conductivity

W/m*ºC

(W/in*ºF)

Specific heat

J/kg*ºC

(J/lb*ºF)

Water

963

(60.2)

0.00046

(0.0000096)

0.00021

(0.00016)

0.659

(0.0093)

4184

(1054)

Air

1.060

(0.066)

0.000020

(0.00000042)

0.00365

(0.00202)

0.0290

(0.00041)

1005

(253)

Water vapor

0.14

(0.0088)

0.0000112

(0.00000023)

0.00365

(0.00202)

0.0212

(0.00029)

1870

(471)

Engine Oil SAE

15W-40

853

(53.3)

0.038

(0.00079)

0.00655

(0.0036)

0.129

(0.00180)

2165

(545)

Fluid properties at 80ºC (176 ºF)

Fluid

Density

Kg/m³

(lb/ft³)

Dynamic viscosity

Pa*s

(lb*s/ft²)

Volumetric

expansion

1/ºC

(1/ºF)

Thermal

conductivity

W/m*ºC

(W/in*ºF)

Specific heat

J/kg*ºC

(J/lb*ºF)

Water

972

(60.7)

0.00035

(0.0000073)

0.00021

(0.00016)

0.675

(0.0095)

4196

(1057)

Air

1.00

(0.063)

0.000021

(0.00000044)

0.00365

(0.00202)

0.0305

(0.00043)

1009

(254)

Water vapor

0.29

(0.018)

0.0000119

(0.00000025)

0.00365

(0.00202)

0.0229

(0.00032)

1880

(474)

Engine Oil SAE

15W-40

841

(52.6)

0.019

(0.00039)

0.00655

(0.0036)

0.127

(0.00178)

2227

(561)

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