Effect of the ambient pressure on the heat release rates of n-heptane pool fires

To investigate the influence of low air pressure on the heat release rate, two groups of the configured experiments on n-heptane pool fires were conducted with burners of three sizes (D = 0.3, 0.35, 0.4 m) in Hefei (99.8 kPa) and Lhasa (66.5 kPa), respectively. The unified standard calculation method confirmed in ISO 9705 was adjusted by introducing the effect of the ambient air pressure. The experimental results indicate that the effect of pressure on the burning rate seems very weak in the case of the thin layer pool fires. However, the heat release rates increase a little at the higher altitude, which may be due to the less soot yield under the lower pressure. The combustion efficiency X_a and the convective heat fraction X_c rises a little with the decreasing pressure, while the radiative fraction X_r shows independent on pressure. The smoke temperature is a little higher at the higher altitude due to the stretching flame.