Abstract
This doctoral study addresses critical knowledge gaps in hydrogen safety engineering associated with the fuelling process in a hydrogen fuelling station (HRS). Using contemporary numerical methods, particularly computational fluid dynamics (CFD), comprehensive modelling techniques were developed to simulate the fuelling process through the entire HRS for the first time. The developed modelling approach allows to encompass all station components in a single CFD model, ranging from the high-pressure tanks, pipes, bends, valves, heat exchanger, breakaway, hose, nozzle, manifold, and a pressure control valve (PCV) down to three onboard storages. Different strategies for flow control in the PCV were tested. The so-called “fixed values” method where used to simplify the PCV as a pipe section. The secondary method was the detailed resolution of PCV geometry using dynamic mesh which is capable of capturing PCV spool dynamics and reproducing the Joule-Thompson effect from first principles. The model was validated using data obtained from the fuelling station experiments at the National Renewable Energy Laboratory (NREL), USA and demonstrated close agreement with the experimental results. The CFD model provided deeper insight and understanding of heat and mass transfer processes during hydrogen fuelling. Besides, the developed technique has a modest CPU time requirement (specifically two days using a standard 32-core workstation with the simplified PCV modelling strategy for the NREL experiment), which allows it to be used as a valuable tool for the development and optimisation of hydrogen fuelling protocols and HRS design.On the other hand, studies show that accidental release of hydrogen is one of the most frequent and hazardous hazards in an HRS. In an attempt to address the potentially hazardous scenario of hydrogen leakage in the presence of external flows at an HRS, a CFD model was validated against experiments performed at Karlsruhe Institute of Technology (KIT), Germany. It was demonstrated that an unexpected reduction of the Low Flammability Limit (LFL) distance, observed in the presence of co-flow and counter-flow ventilation, should be attributed to intensive turbulence in the ventilation fan wake, which may impact safety at an HRS, specifically in confined spaces.
Thesis embargoed until 31 August 2026
Date of Award | Aug 2024 |
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Original language | English |
Supervisor | Vladimir Molkov (Supervisor) & Dmitriy Makarov (Supervisor) |
Keywords
- CFD
- hydrogen
- fuelling
- refuelling
- dynamic mesh
- dispersion
- hydrogen storage