Chapter 6 - Infrared Image Analysis as a Tool for Studying the Horizontal Smoldering Propagation of Laboratory Peat Fires

Abstract

Smoldering fires in peatlands can consume large areas of peat and release important amounts of carbon to the atmosphere as they self-propagate. This chapter focuses on the use of infrared images to characterize the horizontal propagation of smoldering fires in laboratory experiments. In these laboratory experiments an infrared camera takes images of the peat surface at regular intervals during the experiment. We present methods to process and analyze these infrared images that identify the shape and position of the smoldering front, quantify the maximum energy flux, the spread rate and direction of the front and its variability to time. To demonstrate our methods we analyze images from experiments that record the smoldering of dry peats (25% moisture content, mass of water per mass of dry peat) and wet peats (100% moisture content). Infrared images are used to quantify the effect of moisture content upon the smoldering fronts. Our methods demonstrate that smoldering combustion in dry peats has a wider front (6.8 ± 1 cm for the dry peat, 2.4 ± 0.7 cm for the wet peat), a faster spread rate (4.3 ± 1 cm/h for dry peat, 2.6 ± 0.7 cm/h for wet peat), and a lower peak of radiative energy flux (7.1 ± 0.7 kW/m2 for dry peat, 10.51 ± 2.1 kW/m2 for wet peat). Our infrared image analysis is a useful tool to characterize peat fires at an experimental scale. These methods can be applied to peats with different characteristics to identify and compare smoldering propagation dynamics.