Thermophysical properties of lubricants 1

[Gianfranco]

Hi all,

I'm looking for the thermophysical and transport properties(density, specific heat, thermal conductivity, kinematic or dynamic viscosity, surface tension, etc.) of lubricants as cooling/heating media.
I'd found out something on:
a) Neale's Tribology Handbook, but he points out - except the viscosity - generic/average values (Btw: we know that all properties are strongly sensitive to the temperature);
b) Rosenhow-Hartnett's, Handbook, Kays-Crawford's textbook Convective Heat and Mass Transfer, and others ref. books, but all of them list the properties for generic mineral oils.

Do you know any other reference handbooks/textbooks or web sites (or lubricants producers) where reliable thermophysical and transport data on lubricants are shown?

Thanks very much in advance for the help.

Gianfranco
lopad@tin.it

 

[romke]

Accurate values are usually not determined for oil based products that are primarily designed as lubricants. For products that are primarily intended as heat transfer media the various figures usually can be obtained from the supplier. The best way therefore to obtain more information would be to contact your preferred supplier about technical data on his portfolio of heat transfer oils.

You should bear in mind though that those data relate to the use in heating systems. This means that usually non-laminar flow exists and that there are restrictions to the maximum heatflux that is allowed to avoid local cracking of the fluid.

In an engine the oilflow is usually laminar - which means that the heattransporting capacity is much lower - whereas the heatflux might be much higher locally. The latter in these applications is not usually a problem because the oil is changed frequently.

 

[25362]

Heat Transfer by J.P. Holman published by McGraw Hill has tables at the book end. Look for table A-4. You'll find the properties on one kind of unused oil that may be of practical use.

 

[CheTr]

Checked Main Suppliers websites?
Therminol
Dow

 

[Gianfranco]

romke, 25362, CheTr

Thanks for your useful obs/data.

Gianfranco

 

[25362]

Stachowiak and Batchelor in their Engineering Tribology, Elsevier, bring some formulas as follows:

viscosity/temperature: as per the ASTM chart, the abscissa is log₁₀T^oC, the ordinate is log₁₀log₁₀(cS+0.6). The chart works so well that the viscosity-temperature characteristics are frequently specified as "ASTM slope".

specific heat, Cp, J/kgK:

(1.63+0.0034 T^oC)/s^0.5​

where s is the specific gravity at 60^oF.

thermal conductivity, K, W/mK: for a rough estimation,

(0.12/s)(1-1.667 T^oC/10000)​

thermal diffusivity, d, m²/s:

K/(rho.Cp)​

where rho is the density [kg/m³].

 

[jmw]

Many oil companies derive their own relationships for temperature Vs viscosity butwith at least one oil company i found i found exceptionally good correlation with ASTM D341 for mineral and synthetics.
The relationship given in ASTM D341 (viscosites over 2cst)
Log10.log10(v + 0.7) = A-B.log10(T+273) where v is kinematic viscosity in Cst at T degC. Sorry i am not allowed to say which oil company nor what relationship.
????????????
I am curious about the relationship refreenced to from Stachowiak and Batchelor as this differs from the ASTM equation i have beeen using for everything from quench oils to asphalts, including lubricants and fuel oils. Do you have a reference to the ASTM standard from which this is taken? There are a variety of these equations used, some open to very poor results if misused such as the Shell V50 equation (designed for a specific case and often misapplied).

 

[25362]

To jmw, sorry for not having read your query in time. BTW, I've found a BP Viscosity/Temperature chart of BP Trading Limited (1967), in which the viscosity scale is log.log(v+0.8), where v is the kin.visc. in cS. The temperature scale is log T, where T is absolute temperature. The same chart provides the viscosities in degrees Engler, seconds Saybolt Furol, and Saybolt Universal. The abscissa is given in deg F and deg C. The same chart provides graphical blending of viscosities.

 

[Dynad]

Can someone tell me how lithium grease is used to cool plasma welding heads on robotic arms?