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Thermal
Conductivity
Table of Content
Physical
& Chemical Properties
Thermal conductivity is the rate of transfer of heat for a given temperature
gradient through a material. The rate of transfer of heat from a hot
spot to a cooler area in a bearing is a factor in controlling overheating.
Therefore, an oil with a high thermal conductivity would be expected
to lower the temperature of a bearing. Thermal conductivity of a lubricating
oil is used in equations to calculate heat transfer in bearings. The
unit of thermal conductivity is heat over a distance per degree of
temperature. Most mineral oils have approximately the same thermal
conductivity of near 0.1 W m-1 degree C-1. (For reference, the thermal
conductivity of water and ethylene glycol are about 3 times higher
than oils).
Thermal conductivity is measured using ASTM D 2717. This method consists
of a test vessel containing oil and a platinum resistance thermocouple.
Thermal conductivity is determined by measuring the temperature gradient
produced across the liquid sample by a known amount of heat introduced
into the cell by an electrically heated platinum element. Thermal
conductivity increases slightly with higher temperatures.
For more information call 1-888-HERGUTH (437-4884) |
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