Hydrogen-fueled Car Fire Spread to Adjacent Vehicles in Car Parks

Car park fires are known to be dangerous due to the risk of fast fire spread from one car to another. In general, no fatalities are recorded in such fires, but they may have a great cost in relation to damaged cars and structural repair. A very recent example is the Liverpool multi-storey car park fire from December 31, 2017. It destroyed 1400 cars, and parts of the building structure collapsed. This questions the validity of current design praxis of car parks. Literature studies assumes a 12 minutes period for the fire spread from one gasoline fuelled car to another. Statistical research and test from the European commission of steel structures states that in an open car park at most 3-4 vehicles are expected to be on fire at the same time.
A number of investigations have been made concerning vehicles performance in car park fires, but only a few are concerned with hydrogen-fuelled vehicles (HFV). It is therefore important to investigate how these new vehicles may contribute to potential fire spread scenario. The aim of the paper is to report the outcome of car park fire spread simulations involving common fuelled and hydrogen fuelled cars. The case study is based on a typical car park found in Denmark. The simulation applied numerical models implemented in the Fire Dynamic Simulator (FDS). In particular, the focus of the study is on the influence of the parking distance to fire spread to adjacent vehicles in case a TPRD is activated during a car fire. The results help understanding whether different design rules should be envisaged for such structures or how a sufficient safety level can be obtained by ensuring specific parking condition for the hydrogen-fuelled cars.