# Heat removed by air at z

Heat removed by the air in the tunnel, at the point z in the cable route, which is equal to $C_{av} \frac{\partial \theta_{at}(z)}{\partial z}$.

Symbol
$W_{a_{z}}$
Unit
W/m
Formulae
$\frac{N_{c} N_{sys} W_{tot} \left(T_{e} + T_{t}\right) + \theta_{a} - \theta_{at_{z}}}{T_{a} + T_{e} + T_{t}}$
$T_{a}$
$T_{e}$
$T_{t}$
$\theta_{a}$
Ambient temperature [$^{\circ}$C]
$\theta_{at_{z}}$
$W_{tot}$
Used in
$\theta_{o_{z}}$
$\theta_{t_{z}}$