Effects of Ambient Pressure on the Mass Burning Rate and Heat Release Rate of n-Heptane Pool Fire

Abstract

This research aims to investigate the effect of ambient pressure on the burning rate and heat release rate (HRR) of n-heptane pool fire. The experiments were performed in a large-scale altitude chamber of size 2 m×3 m×4.65 m under series of pressure, 24kpa, 38 kPa, 64 kPa and 75 kPa to 90 kPa. A round steel fuel pans of 34 cm in diameter and 15 cm in height was chosen for the pool fire tests. The fuel pan was filled with 99% pure liquid n-Heptane. Experimental results show that the burning rate increases rapidly after ignition until it reaches to the peak, and then maintains at a relatively stable stage. It decreases gradually until the flame extinguishes. The burning time is longer at lower pressure. The mean mass burning rate at the steady burning stage increases exponentially with pressure as ṁ ∼ Pα, with α = 0.68. HRR curve has a similar trend with the burning rate. The maximum HRR increases from 27kW to 62kW as the pressure rises from 24kPa to 90kPa. It is concluded that the ambient pressure has a significant effect on the fire heat release rate, and will further influent on other fire parameters.