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. Considering air flow used by the Cableizer method, the equation uses the distance between second last and last value calculated and the temperature gradient between those two points. Heinhold considers still air, so the total heat to be removed is the sum of all losses multiplied by the tunnel length.

$\frac{\rho_{gas} A_t c_{p,gas} \Delta \theta_{at} V_{air}}{\Delta L}$ventilated tunnel (multi-system)
$\frac{\left(T_t+T_e\right) N_{sys} N_c W_{tot}-\theta_{at,L}-\theta_a}{T_a+T_t+T_e}$ventilated tunnel (IEC 60287-2-3)
$W_{sum}$in channel (Heinhold)