Numerical study of hydrogen leakage, diffusion, and combustion in an outdoor parking space under different parking configurations

This presentation is part of the 2022 FLUG Meeting.

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About the presentation

Title: Numerical study of hydrogen leakage, diffusion, and combustion in an outdoor parking space under different parking configurations 

As the number of hydrogen fuel cell vehicles (HFCVs) being used is increasing, confirming that their safety level is the same as that of gasoline vehicles is becoming important. HFCVs are commonly parked in outdoor spaces. Thus, the safety of HFCVs in garage scenarios should be ensured, and related regulations, codes, and standards for preventing accidents must be developed. 

In this study, the Flame Acceleration Simulator (FLACS-CFD) software was utilized to evaluate the behaviour of hydrogen release, dispersion, and flame propagation in the presence of multiple HFCVs in an outdoor parking space through the activation of thermally activated pressure relief devices (TPRDs). 

The effects of different leak diameters (2, 3, and 4 mm), release directions (upward and downward), and parking configurations (vertical and parallel) on the formation of a flammable gas cloud (FGC) and safety distances were examined, by considering tank blowdown. 

The results showed that larger TPRD diameters resulted in a larger envelope of the FGC; however, it also dissipated faster in outdoor parking spaces. Compared with the vertical parking configuration, the fire-origin HFCV had less impact on adjacent vehicles in the parallel parking configuration. 

The direction of an upward release was found to contribute to a decrease in the volume of the FGC in outdoor parking spaces owing to low congestion. This study highlights the significance of the TPRD diameters and parking configurations, providing guidance for the safe introduction of HFCVs in existing outdoor parking spaces and infrastructure. 

About the speaker

Yahao Shen, PhD Student @ Tongji University 

Yahao Shen is a PhD student in the School of Automotive Studies at Tongji University in Shanghai. His main research interest focuses on hydrogen safety in Fuel Cell Vehicles (FCVs), including: 

• studies on preliminary qualitative hazard identification of FCVs  
• CFD analysis on hydrogen leakage, dispersion, and subsequent combustion from the FCVs by using FLACS-CFD 
• Quantitative Risk Assessment of FCVs in multiple scenarios (garages) by using FLACS-Risk 

Yahao Shen has been using FLACS-CFD for dispersion modelling and consequence analysis for two years.  

About FLUG Meeting

FLACS-CFD User Group (FLUG) provides an opportunity for Gexcon and users of FLACS-CFD to share updates, insights, and experiences.  

 It consists of engaging case study presentations and the latest information on FLACS-CFD software research and development. 

 FLUG has played an integral role in the development of Gexcon’s industry-leading software, which represents more than 40 years of extensive and unrivalled modelling and validation work.