Equation for conductivity value of organic liquids

[patrickraj]

Dear friends,

To calculate thermal conductivity value of organic liquids I found the following formulae in April 12,1975 issue of Chemical Engineering. Is it can be used to calculate thermal conductivity value of SAE 10W oil.

K =0.000877 x Density^(0.83) x (293/T)^(0.38) Cal/(s-cm- °C)
Cp in (CAL/Gm/°C)
Density in (gm/cc)
T in °K in absolute

Please advise. Thanks in advance.

 

[DickRussell]

The API Technical Data Book - Petroleum Refining (chapter 12, 1980) presents Procedure 12A3.1 for conductivity of petroleum fractions of unknown composition, at low pressures:
k= 0.07727 -(4.558E-5)*T
where T is Fahrenheit and k is BTU/ft-hr-F. Average error is said to be 10%, with maximum error 40%. This was a best fit of data from five sources. In 1997, Chapter 12 was revised to improve the accuracy of the above equation form slightly, to 6% average, 24% maximum. They also added a procedure to use when the mean average boiling point of the fraction is known.

 

[25362]

From "Engineering Tribology" (Elsevier) by Stachowiak and Batchelor, the thermal conductivity of mineral and synthetic hydrocarbon based lubricants is in the range of between 0.14 W/mK @ 0^oC to 0.11 W/mK @ 400^oC. For a rough estimation of a thermal conductivity the following formula has been suggested:

K = (0.12/s)(1-0.0001667 T)

K = conductivity, W/mK
s = specific gravity @ 60 deg F
T = temperature, deg C.

It is apparent that an exact value cannot be found. It is also difficult to know what is the effect the additives have on a 10W oil.

If one selects a formula and sticks to it, one's systematic errors will then not change much. It wouldn't be practical to express results with more than two significant figures.

 

[patrickraj]

Dear DickRussell and 25362,

Thanks to both of you.I have an STHE data sheet with SAE 10W oil on S/S. K Value is not given in the data sheet. I try the design with K from these two formulas.

Thanks once again.