Hydrogen Concentration Distribution in Simulated Spaces for a Hydrogen System Installed in a Large Bus in Case of Hydrogen Leakage

Document Number: 2008-01-0727

Date Published: April 2008

Author(s):
Hideki Matsumura - National Traffic Safety & Enviro Lab.

Abstract:
For fuel cell vehicles, which have attracted attention in recent years, the prevention of hydrogen leakage is an essential safety issue.

Large fuel cell buses will require a large space to store the hydrogen system. The behavior of hydrogen that has leaked into such a large space is unknown.

In this report, we studied hydrogen concentration distribution by leaking hydrogen into simulated spaces in two cases: (1) when hydrogen gas tanks are installed on the roof of the bus, and (2) when an electricity-generating system, such as fuel cell stacks, etc., is installed at the rear of the bus.

The results of the experiments show that hydrogen concentration distribution is kept at a constant level throughout each location in the simulated space, depending on the opening area and hydrogen leakage rate. It was also found that the diffusivity of hydrogen in air is extremely high. Hydrogen diffuses through openings, preventing a high concentration from accumulating inside the space, thus keeping the concentration below the lower flammable limit (LFL) of 4% (by volume), in many cases.

File Size: 899K
Product Status: In Stock

Included in: V117-6

See other papers presented at SAE World Congress & Exhibition, April 2008, Detroit, MI, USA, Session: Fire Safety: Hydrogen Vehicle Fire Safety

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