# Heat removed by air at outlet

Heat removed by the air in the tunnel, at the tunnel outlet. Considering the energy carried by the flowing air, the equation uses the distance between second last and last value calculated and the temperature gradient between those two points.

Symbol
$W_{a,L}$
Unit
W/m
Formulae
 $\frac{\left(T_t+T_e\right) N_{sys} N_c W_{tot}-\theta_{at,L}-\theta_a}{T_a+T_t+T_e}$ IEC 60287 $\frac{\rho_{gas} A_t c_{p,gas} \Delta \theta_{at} V_{air}}{\Delta L}$ Air flow
Related
$A_t$
$c_{p,gas}$
$\rho_{gas}$
Gas density [kg/m$^3$]
$T_a$
$T_e$
$T_t$
$\theta_a$
$\theta_{at,L}$
$V_{air}$
$W_{tot}$
Used in
$\theta_{o,L}$
$\theta_{t,L}$