Related Resources: heat transfer

Convection Heat Transfer Coefficients Equations and Calculator

Heat Transfer Engineering
Thermodynamics
Engineering Physics

Simplified relations for natural convection heat transfer coefficients for various geometries in air at atmospheric pressure for laminar flow conditions.

Convection Heat Transfer Equation and Calculator

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Geometry
W/m2 · °C
(ΔT in °C, L or D in mm)

Btu/h · ft2
(ΔT in °F, L or D in ft)

Vertical Plate or Cylinder
Vertical Plate or Cylinder
hconv = 1.42 (ΔT / L)0.25
hconv = 0.29 (ΔT / L)0.25
Horizontal Cylinder
Horizontal Cylinder
hconv = 1.32 (ΔT / L)0.25
Open
hconv = 0.27 (ΔT / L)0.25
Hot Surface Facing Up
Hot Surface Facing Up

Horizontal plate (L = 4A/p,
where A is surface area
and p is perimeter
hconv = 1.32 (ΔT / L)0.25

Open

Horizontal plate (L = 4A/p,
where A is surface area
and p is perimeter

hconv = 0.27 (ΔT / L)0.25

Open
Hot Surface Facing Down
Hot Surface Facing Down

Horizontal plate (L = 4A/p,
where A is surface area
and p is perimeter
hconv = 0.59 (ΔT / L)0.25
Open
Horizontal plate (L = 4A/p,
where A is surface area
and p is perimeter
hconv = 0.12 (ΔT / L)0.25
Components on Circuit Board
Components on Circuit Board
hconv = 2.44 (ΔT / L)0.25
hconv = 0.50 (ΔT / L)0.25
Small Components, Wires in Free Air
Small Components, Wires in Free Air
hconv =3.53 (ΔT / L)0.25
hconv = 0.72 (ΔT / L)0.25
Sphere
Sphere
hconv = 1.92 (ΔT / L)0.25
hconv = 0.39 (ΔT / L)0.25