Session: 03-03 Hydrogen Sustainability, Affordability and Safety

Paper Number: 101383

101383 - Characterization of High Pressure Hydrogen Leakages 

Energy transition drives major changes in the energy conversion scenario and requires gas turbines manufacturers to explore strategies to heavily reduce carbon emissions. The possibility to fuel gas turbines with hydrogen, pure or blended, arises several challenges when designing gas turbines (GTs). The introduction of hydrogen impacts the combustion and in general efficiency of the gas turbine, but also requires additional evaluations on the design of auxiliary systems from a safety point of view. The design of a gas turbine package is oriented to reduce the possibility and the extent of a fuel gas leakage inside the GT enclosure, but this event cannot be excluded. In such scenario, the presence of hydrogen poses higher risks of flammability with respect to methane. Therefore, the accidental accumulation of hydrogen inside GT enclosures, when a leak occurs, needs to be investigated in detail, to assess whether the ventilation system is effective in diluting the gas cloud. In this context, the purpose of this work is to address the modelling technique for hydrogen leaks when simulating such scenarios.

Inside a GT enclosure fuel leaks result in under-expanded jets because of the large difference in pressure between the fuel gas piping and the GT enclosure environment. Theoretical evaluations allow to approach these jets qualifying the leak regime with the storage-to-ambient pressure ratio. In this work, a parametrical study for jets of different blends, from pure methane to pure hydrogen, is performed numerically considering pressure ratios spanning from 15 to 45. Once the free jet is characterized, the same parameters are varied when imposing two different crossflow ventilation velocities (U₁=3 m/s and U₂=5 m/s). The simulations are stationary RANS carried out with ANSYS Fluent with turbulence closure model k-w SST, chosen after a sensitivity analysis, and jet inlet condition imposed with the pseudo-source approach of Ewan and Moodie (1986). After results validation with available experimental data for the free jet, a discussion on the axisymmetric behaviour is extended to all blends, focusing on the effect of the fuel composition and the ventilation in crossflow. As a conclusion, without ventilation hydrogen flammable clouds are three time broader than the ones obtained with methane, significantly increasing the hazardous region around the leak. When ventilating the region, the cloud behaves differently if hydrogen is present. Three-dimensional phenomena are observed and imply the need of safety-related considerations to be discussed.

Presenting Author: Davide Cerbarano Sapienza University of Rome

Presenting Author Biography: Mr Cerbarano graduated in mechanical engineering at Sapienza University of Rome.
He started a PhD in 2022 at Department of Mechanical and Aerospace Engineering in collaboration with Baker Hughes. The main topic of his PhD is the study of fuel leakeges in a gas turbine enclosure, with particular interest in hydrogen and the safety concerns of its use.

Authors:

Davide Cerbarano Sapienza University of Rome
Ermanno Lo Schiavo Baker Hughes
Lorenzo Tieghi DIMA - Sapienza University of Rome
Giovanni Delibra Sapienza University of Rome
Stefano Minotti Baker Hughes
Alessandro Corsini Sapienza University of Rome