Thermal conductivity

 

The thermal conductivity lambda (λ) of a solid, a fluid or a gas may basically be understood as the speed at which a defined amount of heat travels as it goes through a particular substance. A low λ value means low thermal conductivity.

For both liquids and gases lambda highly depends on the temperature, whereas pressure dependence is comparitively low. The measure for lambda is W/(m*K) (Watts per Meter and Kelvin).

Typical lambda values for different fluids

FluidThermal conductivity λ (W/(m*K))
gasoline0,140
glycerin0,286
machine oil0,126
ethanol0,185
water @ 50°F (10°C)0,580
water @ 140°F (60°C)0,644

 

 

Lambda measurement for fluids, pastes and gels (flucon LAMBDA)

flucon's Measuring system LAMBDA allows you to determine the temperature-dependent thermal conductivity of liquids, pastes or gels with ease. With its hot-wire technology the LAMBDA is both precise and comfortable to handle. Its measuring range from 0,01 to 2 W/(m*K) and its temperature range -50°C to 150°C (HT version for even higher temperatures available) make it the perfect tool for your thermal fluid analysis.

Workflow for the determination of the thermal conductivity (flucon fluid analysis)

flucon not only offers their portable LAMBDA measuring system but also in-house fluid analysis in our own high pressure laboratory. Customers may send in small samples (300 ml) of the fluid they would like to have tested and then the following steps will be performed:

  • Laboratory measurement of the thermal conductivity as a function of temperature and pressure using a transient measuring method preventing an influence of convective flow of heat on the measuring result
  • Mathematical description of the pressure/temperature-dependant thermal conductivity
  • Graphical data preparation