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Air temperature in tunnel increase

Fictitious increase of ambient temperature to account for the ventilation in a tunnel.

Symbol
$\Delta \theta_{0t}$
Unit
K
Formulae
$\frac{\left(\theta_{init}-\theta_a\right) \left(T_t+T_e\right)}{T_a+T_t+T_e} e^{\frac{-L_T}{L_0}}$
Related
$L_0$
Reference length of the tunnel [m]
$L_T$
Length of the tunnel [m]
$T_a$
Star thermal resistance of air [K.m/W]
$T_e$
External thermal resistance of tunnel [K.m/W]
$T_t$
Star thermal resistance of tunnel [K.m/W]
$\theta_a$
Ambient temperature [°C]
$\theta_{init}$
Air temperature with no load [°C]
Used in
$I_c$
Conductor current [A]
$\theta_c$
Temperature of conductor [°C]