Numerical analysis for methane explosion in closed spaces

Abstract

Owing to regulations on environmental pollutants emitted by ships, the use of methane fuel is growing as the number of liquefied-natural-gas fueled ships has increased. However, methane has a high risk of explosion; therefore, there is a need to study the explosion characteristics and prepare countermeasures. In this study, we theoretically calculated the adiabatic flame temperature and maximum explosion pressure, and performed a numerical analysis of explosions based on previous experiments. The theoretically calculated adiabatic flame temperature and maximum explosion pressure were, respectively, 2,823 K and 9.28 bar, and the analysis results were 2,347 K and 7.5 bar, showing a difference of 476 K and 1.78 bar. However, the maximum explosion pressure according to the test results was 7.3 bar, which differed by 2.6% from the analysis results, and showed a margin of error within 5% in most of the compared concentrations. As a result of substituting the adiabatic flame temperature derived from the analysis results into the theoret-ical equation, the maximum explosion pressure became 8.1 bar, which differed by 7.5% with respect to the maximum pressure from the analysis results. Although the numerical values from explosion analysis were lower than those from the theoretical calculations, the analysis results were reliable because the maximum explosion pressure and the adiabatic flame temperature were similar to the test results at most of the concentrations. Therefore, the analysis results may be useful for finding an analytical approach to explosions inside dual-fuel engines in the future and help determine the size of relief valves required for dual-fuel engines.