Natural Convection

Natural Convection Heat Transfer Coefficient Correlations (S.I. units)

4. With an isothermal horizontal cylinder Fluid = air

Inputs Calculations

30 30

60 318

45 0.7

1.10.E+09

0.7 m

7.60E+08

1.1

0.0000187

106

1

4.08

1000

Fluid Thermal

0.027 J/s-m-K

Fluid Thermal

0.003143

* For an Excel spreadsheet that can be downloaded to calculate the density of a gas

"Excel Templates for Venturi and Orifice Flow Meter Calculations," at:

Fluid Temp, T¥ = oC Temp Diff, DT = oC

Surface Temp, Tw = oC Abs. Film Temp, Tf = oK

Film Temp., Tf = oC Prandtl Number, Pr =

[ Tf = (T¥ + Tw)/2 ]

Grashof Number, Gr =

Cylinder Diam., D =

Rayleigh No., Ra =

Fluid Density, r* = kg/m3

Fluid viscosity, m = N-s/m2

Nu =

Fluid Sp. Heat, Cp = J/g-oK

h = W/m2-K

Fluid Sp. Heat, Cp = J/kg-oK

Conductivity, k =

Expans. Coeff, b = oK-1

with known molecular weight and specified temperature and pressure, see:

http://www.brighthub.com/engineering/civil/articles/83825.aspx

Equations for Natural Convection - Isothermal Horizontal Cylinder