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Cryogenics tools

Wiedemann-Franz law

The Wiedemann-Franz law relates the thermal and electrical conductivity of metals. It refers to thermal conductivity due to electrons; in alloys lattice (phonon) conductivity may be significant, raising the thermal conductivity above the prediction from the Wiedemann-Franz law. The calculator below converts between thermal conductivity and electrical resistivity using the Wiedemann-Franz law.

Choose one of:

Thermal conductivity: W/m/K value

or

Electrical resistivity: Ohm m

and also choose:

Temperature: (K)

The theoretical value of 2.45 10-8 W Ohms K-2 is generally valid near room temperature and at low temperatures (around 4 K and below). At intermediate temperatures, the value depends on the material; you can supply an alternative value below:
Lorenz number: W Ohms K-2

Helium boil-off

This calculator estimates the amount of liquid helium boiled off for a given heat input.

Heat input: W

Other tools

A calculator which gives thermal conductivity values for pure and alloyed copper and aluminium from 1 to 300 K as a function of low temperature conductivity, resistivity, or RRR, can be found here.

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Page created: Adam Woodcraft
Last edited 2009-8-17     Site map
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