Online meeting with car OEMs, 9 February 2021



Online meeting between the project consortium and the car manufacturers, represented by Toyota Motors and other car OEMs, took place 9 February 2020. Overall, the meeting was attended by 9 representatives of car manufacturers and more than 20 project partners. First, the overview of the project organisation, development and major interim results was given by Dr Dmitriy Makarov (Ulster University) on behalf of the partners. The presentation outlined HyTunnel-CS project strategy which is considering a vehicle and a tunnel as a single system, and allowing flexibility in use of readily existing tunnels and underground infrastructure with present-day safety systems given safety was properly addressed on the car side.  Brief into project results was focused on the practical considerations important to the car manufacturing industry, like

    • What can go wrong with respect to hydrogen powered vehicles in tunnels?
    • How likely is it?
    • What could be the consequences of an accident with hydrogen powered vehicles in a tunnel?
    • What can be done to reduce hazards and associated risks of such an accident?
    • What are the intermediate new insights gained from the project and what is to be expected in the near future?
    • What are the knowledge gaps today with respect to the safety assessment of  tunnels used by hydrogen powered vehicles?

Major analytical, numerical and experimental results of the project were presented together with the research plans for the remaining project duration period, including

    • Safety strategy to exclude flammable mixture formation under tunnel ceiling
    • Effect of hydrogen release direction and tunnel slope on flammable mixture formation,
    • Engineering consideration to prevent hydrogen flame blow-off from TPRD during tank blowdown,
    • Experimental and analytical work to underpin mitigation of pressure peaking phenomenon,
    • Engineering tools to design against or mitigate
      • deflagration-to-detonation transition,
      • deflagrations following delayed ignition,
      • blast wave following tank rupture in a fire, etc.

The project presentation was concluded by Dr Alfonso Bernad (Foundation Hydrogen Aragon) who presented activities and functions of Stakeholders Advisory Board (SAB), and invited the car OEMs attending the meeting to join the Board.

The project presentations were followed by round-table discussion, during which the present OEMs described their view of modern hydrogen fuelled vehicles safety aspects, reliability of particular safety components and safety design issues. Prof Vladimir Molkov (Ulster University) provided detailed insight into available engineering tools to aid fire safety of hydrogen tanks and strategies to prevent tank rupture in a fire allowing to exclude thermal and pressure hazards associated with tank rupture and safely introduce hydrogen fuelled vehicles in tunnels and underground infrastructure.

Ad-hoc rail-specific online meeting, 18 February 2021



The need for ad-hoc gathering to address rail-specific accident scenarios became apparent during the 5th progress project meeting early February 2021. The meeting to discuss the issue and to provide insight into practical aspects of rail tunnel design and operation was organised 18 February 2021.

During the meeting the SAB members Mr Mike Lipscomb (Rail Standards and Safety Board) and Mr Rory Dickerson (NetworkRail) presented typical rail tunnel designs, discussed features specific for rail tunnels and outlined questions on hydrogen storage safety from rail industry perspective, such as

    • thermal and pressure hazards resulting from credible accident scenarios of TPRD release or pipework leakage,
    • suggestions for thermally-activated pressure relieve device (TPRD) design strategy (orifice, release orientation, etc.),
    • guidance on size of individual tanks,
    • engineering tools to predict thermal and pressure hazards, etc.

Prof Knut Vågsæther (University of South-Eastern Norway) presented Norwegian project “Mobility Zero Emission Energy Systems” (MoZEES, which focuses, between other issues, on hydrogen value chain and safety, including safety in tunnels.

Dr Mike Kuznetsov (Karlsruhe Institute of Technology) gave detailed description of a novel engineering correlation to predict hydrogen-flame acceleration and transition to detonation, which is particularly important for hydrogen applications in rail tunnels due to their exceptionally congested layout.

Dr Dmitriy Makarov (Ulster University) introduced the issue of attached jets and jet fires, which are believed to be relevant to releases from TPRDs in tunnels due to restricted air entrainment and which present significantly higher hazards, i.e. providing longer flammable envelopes for unignited releases and longer jet flames for ignited jets.

The meeting was attended by 28 partners and SAB members. After live discussion the meeting participants agreed to intensify study of rail-specific accident scenarios. Though opportunities for detailed study of hydrogen hazards in rail tunnel are limited by the project budget, some experimental investigation of these important accident scenarios appear to be plausible.