CFD Simulation of the Release of LN2 Inside a Tunnel

The present study is aimed at investigating the dispersion of nitrogen accidentally released from a liquefied nitrogen (LN2) road tanker, carrying 10.6 t of liquid product, inside a model tunnel. Two severe release scenarios have been assumed, with hole sizes 250 and 700 mm, respectively: under these conditions all the LN2 present in the tanker is completely discharged in a very short time (less than 2 min, for both scenarios). A CFD (Computational Fluid Dynamics) approach was used to simulate cold nitrogen dispersion. The study cases show that the massive release of liquid nitrogen within tunnels may pose serious hazards also in the case of rather short galleries: the combined effect of very low temperatures and oxygen deficiency may impair people eventually present inside the tunnel from leaving their vehicles and escape safely to the open.