No abstract

Fire dynamics inside an open-plan compartment with an exposed CLT ceiling and glulam columns: CodeRed #01, Fire and Materials.

Peat fires are a global-scale source of carbon emissions and a leading cause of regional air quality deterioration, especially in Southeast Asia. The ignition and spread of peat fires are strongly affected by moisture, which acts as an energy sink. However, moisture effects on peat fire emissions are poorly understood in the literature. Here we present the first experimental work to investigate transient gas and particle emissions for a wide range of peat moisture contents (MCs). We include drying, ignition, smouldering spread, and even flaming stages. Peat samples conditioned to different MCs were burnt in the laboratory where a suite of diagnostics simultaneously measured mass loss rate, temperature profiles, real-time concentration of 20 gas species, and size-fractioned particle mass. It was found that MC affects emissions, in addition to peat burning dynamics. An increase in MC below a smouldering threshold of 160% in dry basis leads to a decrease in NH3 and greenhouse gas emissions, including CO2 and CH4.The burning of wet peat emits more coarse particles (between 1 to 10 m) than dry peat, especially during the ignition stage. In contrast, flaming stage emits mostly soot particles less than 1 m, and released 100% more fully oxidised gas species including CO2, NO2 and SO2 than smouldering. The examination of the resulting modified combustion efficiency (MCE) reveals that it fails to recognise with sufficient accuracy for smouldering combustion, especially for wet peat with MC >120%. MCE confuses drying and flaming, and has significant variations during the ignition stage. As a result, MCE 2 is not valid as a universal fire mode indicator used in the field. This work fills the gap knowledge between moisture and emissions, and provides a better understanding which can help mitigate peat fires.

The traditional design fires commonly considered in structural fire engineering, like the standard fire and Eurocode parametric fires, were developed several decades ago based on experimental compartments smaller than 100 m2 in floor area. These experiments led to the inherent assumption of flashover in design fires and that the temperatures and burning conditions are uniform in the whole of the compartment, regardless of its size. However, modern office buildings often have much larger open-plan floor areas (e.g. the Shard in London has a floor area of 1600 m2) where non-uniform fire conditions are likely to occur. This paper presents observations from a large-scale fire experiment x-ONE conducted inside a concrete farm building in Poland. The objective of x-ONE was to capture experimentally a natural fire inside a large and open plan compartment. With an open-plan floor area of 380 m2, x-ONE is the largest compartment fire experiment carried out to date. The fire was ignited at one end of the compartment and allowed to spread across a continuous wood crib (fuel load ~ 370 MJ/m2). A travelling fire with clear leading and trailing edges was observed spreading along 29 m of the compartment length. The flame spread rate was not constant but accelerated with time from 3 mm/s to 167 mm/s resulting in a gradually changing fire size. The fire travelled across the compartment and burned out at the far end 25 min after ignition. Flashover was not observed. The thermocouples and cameras installed along the fire path show clear near-field and far-field regions, indicating highly non-uniform spatial temperatures and burning within the compartment. The fire dynamics observed during this experiment are completely different to the fire dynamics reported in small scale compartments in previous literature and to the assumptions made in traditional design fires for structural design. This highlights the need for further research and experiments in large compartments to understand the fire dynamics and continue improving the safe design of modern buildings.