Burried pipes

[MortenA]

Anybody know any good correlations (pref. with a litterature ref.) for a aproximation of the heat loss from a buried pipe where the value should be a heat resistance coefficient R or equivalent (so that the value can be incorporated in a standard U estimation).

I know the one that is often seen lifted from the "Transactions of the American Institute of Electrical Engineers, The temperatures of buried Caples and Pipes" Volume 68, Part I 1949" that are commenly used. But i have been told that it is inaccurate at low pipe temperatures.

Best Regards

Morten Andersen

 

[CarlB]

My reference is "Cold Climate Utilities Manual" by the Canadian Society for Civil Engineering. Original equations/development likely from other sources.

For bare pipe buried in soil, depth z to center, Rp is pipe radius, k is soil conductivity, Ts is temperature at surface, Tz is temperature at pipe depth, Tw is temperature of fluid in pipe;

Rg=[arccosh (z/Rp)]/2*pi*k;

and q=(Tw-Ts)/Rg ---heat loss per unit length