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Two simplified models for predicting minimum extinguishing concentration(MEC) of ultrafine water mist(UFM)(<10 m) were developed based on limiting oxygen concentration(LOC) and combustion limit temperature(CLT),respectively.Experiment was conducted using a modified cup burner which can reduce the surface adsorption of UFM.Two typical liquid fuels,n-heptane and ethanol,were used in the experiment.Tests using the same scenario were repeated 20 times or 10 times according to the variance of extinguishing time.The average and the standard deviations of extinguishing time were used to evaluate the fire extinguishing performance of UFM.Experimental results agree well with the model based on LOC,and disagree with the model based on CLT.The disagreements were explained by analyzing flow behavior of UFM.It was concluded that the primary mechanism of fire extinguishment with UFM was oxygen dilution.
Two simplified models for predicting minimum extinguishing concentration (MEC) of ultrafine water mist (UFM) (<10 m) were developed based on limiting oxygen concentration (LOC) and combustion limit temperature (CLT), respectively. burner which can reduce the surface adsorption of UFM.Two typical liquid fuels, n-heptane and ethanol, were used in the experiment. Tests using the same scenario were repeated 20 times or 10 times according to the variance of extinguishing time.The average and the standard deviations of extinguishing time were used to evaluate the fire extinguishing performance of UFM. Experimental results agree well with the model based on LOC, and disagree with the model based on CLT. disagreements were explained by analyzing flow behavior of UFM. It was said that the primary mechanism of fire extinguishment with UFM was oxygen dilution.