Ventilation Control in Bifurcate Tunnels with Distributed Vents

We propose an optimal ventilation control model for bifurcate vehicular tunnels with distributed pollutant discharge points. The control problem is formulated as a nonlinear integer program that aims to minimize energy cost of fans while meeting multiple air quality requirements inside the tunnel and near the vents. Based on the steady-state solutions to tunnel aerodynamics equations, we propose a reduced form model for air velocities as explicit functions of ventilation decision variables and traffic intensity. The pollutant dispersion model is then incorporated for the derivation of optimal pollutant discharge control strategies. A case study of a new urban tunnel in China shows that the scheduling of fan operations based on the proposed model can effectively achieve different air quality standards under varying traffic intensity.