Experimental study on combustion characteristics of pool fires in a sealed environment

The results of a series of bench-scale pool fire experiments to explore the burning characteristics under a sealed environment are presented in this work.Although the oxygen fraction in the space gradually decreases by burning consumingin comparison to open conditions, the transient heat release rate can still be calculated using the PER approach using the in-situ measured oxygen fraction. The dimensionless flame height can still be calculated using the McCaffrey's model for open conditions, but a greater coefficient should be used because the flame burns in a 'hunger' mode when the oxygen fraction is low. The current non-sealed fire model for centerline temperature rise of pool fires is unsuitable for the sealed environment: the centerline temperature rise decreases more quickly than that predicted by Nasr's model developed for cases with a limited ventilation in the middle and later stages of the fire. A new engineering model has been developed in this study by curve fitting sealed fire test results. Pagni's law can still be suitable to describe the relationship between the frequency of flame oscil-lation and the diameter of a pool fire in a sealed environment, but the modified coefficients are required.

Automated summary

This study presents the results of bench-scale pool fire experiments conducted in a sealed environment to investigate burning characteristics. Although the oxygen fraction in the space decreases gradually during burning, the PER approach can still be used to calculate the transient heat release rate using in-situ measured oxygen fraction. The dimensionless flame height can still be calculated using McCaffrey's model, but with a greater coefficient due to the flame burning in a 'hunger' mode with low oxygen fraction. A new engineering model was developed by curve fitting sealed fire test results to address the limitations of the current non-sealed fire model for centerline temperature rise of pool fires in a sealed environment. Pagni's law can still describe the relationship between flame oscillation frequency and pool fire diameter in a sealed environment, but with modified coefficients.