Diameter pipe (inner)

Symbol

$D_{in}$

Unit

m

Used in

$h_{in}$

Heat transfer coefficient internal [W/(K.m$^2$)]

$\mathrm{Nu}_w$

Nusselt number surface—water

$\mathrm{Re}_w$

Reynolds number water

$U_{buried}$

OHTC pipe fully buried [W/(K.m$^2$)]

$U_{exposed}$

OHTC part of pipe in contact with water [W/(K.m$^2$)]

$U_{ground}$

OHTC part of pipe in contact with ground [W/(K.m$^2$)]

$U_{inwall}$

OHTC inside film + pipe wall [W/(K.m$^2$)]