Thermal conductivity λ

The thermal conductivity (λ) of a solid object, a liquid or a gas is determined by the speed by which – if heating up occurs – the temperature rise spreads throughout the substance. A low λ-value corresponds to a low degree of thermal conductivity. For fluids as well as for gases, the thermal conductivity is highly dependent on the initial temperature of the substance and also, to a comparatively minor degree, it depends on the pressure surrounding the substance. The unit in which the thermal conductivity is expressed is W / (m K) (Watt per meter and Kelvin).

Typical values for the thermal conductivity of fluids

Fluid Thermal conductivity λ (W/(m*K))
Petrol / gasoline 0,140
Glycerine 0,286
Machine oil 0,126
Ethanol 0,185
Water 10°C 0,580
Water 60°C 0,644