The Fire Simulation in a Road Tunnel

Fire behaviour, especially its interaction with ventilation system in tunnels, is still a challenging issue for road tunnel designers .This paper presents the results of a study investigating the influence of a road tunnel ventilation system, on conventional fires. For this purpose, a 25 MW fire corresponding to a conventional fire in a road tunnel was simulated using 2D numerical modelling, for transient viscous multi-component gas at low Mach numbers to study smoke and heat propagation within a road tunnel under fire .Complete Navier-Stocks and Reynolds equations were solved using developed algorithm of numerical modelling .The results from a series of calculations were compared with results of experimental researches to examine the accuracy and stability of the calculations .The comparisons showed that the algorithm provided a good description of physical processes in selected class of flow. It was also concluded that calculation accuracy is not lower than those obtained from established simulation software programs . The stability and good convergence of the algorithm was confirmed by separate calculations with different grid patterns for the tunnel under consideration .The results revealed that the temperature at tunnel wall may rise up to 900oC. The concentration of smoke may also increase up to 95 %with a burning truck .Results were applied to assess the ventilation system designed for a new long road tunnel in case of fire .The results from the study along with other information were applied to assess the designed ventilation system and to establish the suitable fire fighting and rescue plan

Epitaxial B Graphene Large Scale Growth and Atomic Structure

Embedding foreign atoms or molecules in graphene has become the key approach in its functionalization and is intensively used for tuning its structural and electronic properties. Here, we present an efficient method based on chemical vapor deposition for large scale growth of boron-doped graphene (B-graphene) on Ni(111) and Co(0001) substrates using carborane molecules as the precursor. It is shown that up to 19 at. % of boron can be embedded in the graphene matrix and that a planar C–B sp² network is formed. It is resistant to air exposure and widely retains the electronic structure of graphene on metals. The large-scale and local structure of this material has been explored depending on boron content and substrate. By resolving individual impurities with scanning tunneling microscopy we have demonstrated the possibility for preferential substitution of carbon with boron in one of the graphene sublattices (unbalanced sublattice doping) at low doping level on the Ni(111) substrate. At high boron content the honeycomb lattice of B-graphene is strongly distorted, and therefore, it demonstrates no unballanced sublattice doping