Performance testing of wildland fire chemicals using a custom-built heat flux sensor

Abstract

A simple and effective laboratory test methodology was developed for differentiating wildland fire chemicals based on the ignition time of vegetative fuel samples. The test apparatus consisted of an electric-powered radiant heater that was used to produce a uniform radiant thermal load to ignite the vegetative fuel samples. The samples, treated with wildland fire chemicals, were mounted on to a load cell to determine the transient mass loss during the combustion process. A custom-built heat flux sensor, that was modified and tested to reduce high errors, was used to determine the time to flaming ignition. The time to flaming ignition was also measured using transient mass loss data of the vegetative fuel samples. Statistical t-test analysis was conducted on the time to flaming ignition to determine whether the results were statistically significant for the different chemical treatments. The results indicated that the test methodology allowed for effective differentiation between the wildland fire chemical treatments by comparing their mean ignition times. The narrow standard deviations of the average ignition times suggested that the test methodology was able to produce repeatable results.

Improvement of heat release methodologies using mass loss calorimeter and oxygen consumption hood to assess flammability of wood plastic composites

“…This mass flow rate of the flue gas formula differs slightly from a similar analysis (Quintiere et al 11 or Anderson) 10 presumably because of the difference in the chimney design. The placement of the flue gas thermopile at the top of the chimney was then appropriate to implement equation (21), but the effect of the heat capacity of the thermocouples required a deconvolution of the thermopile signal with a time constant to obtain the true flue gas temperature at the top of the chimney.…”

“…Another sensible enthalpy rate approach used the relatively thicker aluminium plates surrounding the combustion source with thermocouples on both sides of the plate and measured the flue gas velocity with an anemometer (It is known as thermal canister, Anderson). 10 This is to measure temperature gradient and therefore obtain heat loss values via heat conduction approximation. However, the wall surface temperature gradient multiplied by its thermal conductivity is fundamentally equal to the convective and radiant heat losses to the environment whether in steady state or in transient mode, as modeled in equations (18) and (19).…”

“…Mass loss data were processed using a Savitzky–Golay (SG) digital filter followed by an exponential low-pass filter so that the mass loss profile as multiplied by flaming HOC of reference materials was synchronized with the HRR profile of either the sensible HRR or that of HRR via oxygen consumption. Finally, for this study, alternative sensible HRR designs were evaluated for measuring the enthalpy heat rise of the flue gas and the corresponding convective and radiative heat losses to the firebox and chimney walls for determining the flaming HRR (Moussan et al, 8 Filipczak and Lyon, 9 Anderson, 10 Quintiere et al, 11 ASTM E1321 (LIFT apparatus), 12 and ASTM E906. 13 ).…”