OHTC of part of pipe in contact with ground

Overall heat transfer coefficient (OHTC) of the pipe in contact with ground.

Symbol
$U_{ground}$
Unit
W/(K.m$^2$)
Formulae
$\frac{1}{\frac{D_{ref}}{D_{in} h_{in}}+\frac{D_{ref}}{D_{wall} U_{wall}}+\frac{D_{ref}}{D_{ext} h_{ground}}}$Carslaw & Jaeger
$\frac{1}{\frac{1}{h_{ground}}+\frac{1}{h_{amb}}}$Morud & Simonsen / OTC 23033
$\frac{1}{\frac{D_{ref}}{D_{in} h_{in}}+\frac{D_{ref}}{D_{wall} U_{wall}}+\frac{1}{h_{buried}}+\frac{1}{h_{amb}}}$Ovuworie
Used in
$U_{partially}$