**Biot number (Bi)**

The Biot number, Bi is dimensionless, which is ratio between of the internal and external resistance.

where

- h is the average heat Transfer coeficient.
- L length dimention, The ratio between the volume and the surface area.
- k thermal conductivity.

**Drag coefficient (Cf)**

The drag coefficient is the ratio of surface shear stress and the free-stream kinetic energy

**Eckert number (Ec)**

Eckert number (Ec) define he relationship between a flow’s kinetic energy of flow and the boundary layer enthalpy difference. This dimensionless number is used to characterize heat transfer dissipation.

**Fourier number (Fo)**

Fourier number (Fo) is a dimensionless number that characterizes transient heat conduction. The Fourier number (Fo) is a time dimensionless number which is the ratio between the rate of heat conduction and the rate of internal energy storage.

**Friction factor ( f )**

The friction factor f may varies with temperature unknown extent.

The friction factor is dimensionless number is used to estimate the pressure drop for internal flow through ducts or pipe…

**Grashof number (GrL)**

Grashof number, Gr, is the ratio between the buoyant forces and the viscous forces.

Grashof number is dimensionless numbers in heat transfer but specially used also in fluid dynamics.

**Colburn j factor ( jH)**

j factor is a dimentionless number for heat transfer.The main advantage of the *j* factor is to determine the heat transfer coefficient, performance prediction of heat exchangers…

**Nusselt number (NuL)**

Nusselt number (NuL) is the ratio between the convection heat transfer and conduction heat transfer.

The Nusselt number is correlated with Reynolds number and the Prandtl number

**Peclet number (PeL)**

Peclet number (PeL) is the product of Reynolds and the Prandtl number. The Peclet number define the ratio between the advective transport rate and the diffusive transport rate.

**Rayleigh number (Ra)**

**Reynolds number (ReL)**

**Stanton number (St)**

## Dimensionless Numbers in Heat Transfer Table

## More Heat Transfer Calculator

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