Mark A. Dietenberger

Investigation of black and brown carbon multiple‐wavelength‐dependent light absorption from biomass and fossil fuel combustion source emissions

Quantification of the black carbon (BC) and brown carbon (BrC) components of source emissions is critical to understanding the impact combustion aerosols have on atmospheric light absorption. Multiple-wavelength absorption was measured from fuels including wood, agricultural biomass, coals, plant matter, and petroleum distillates in controlled combustion settings. Filter-based absorption measurements were corrected and compared to photoacoustic absorption results. BC absorption was segregated from the total light extinction to estimate the BrC absorption from individual sources. Results were compared to elemental carbon (EC)/organic carbon (OC) concentrations to determine compositions impact on light absorption. Multiple-wavelength absorption coefficients, Angstrom exponent (6.9 to 0.9 OC/TC), source emissions have variable absorption spectra, and nonbiomass combustion sources can be significant contributors to BrC.

Comparison of test protocols for the standard room/corner test

As part of international efforts to evaluate alternative reaction-to-fire tests, several series of room/corner tests have been conducted. Materials tested were mostly different wood products but included gypsum board and a few foam plastics. This is a review of the overall results of related studies in which the different test protocols for the standard room/corner test were used, Differences in the test protocols involved two options for the ignition burner scenario and whether or not the ceiling was also lined with the test materials. The test materials were placed on three walls of the room in all the tests. The two burner scenarios were (1) 40 kW for 300 s followed by 160 kW for 300 s and (2) 100 kW for 600 s and 300 kW for 600 s. The 40 and 160 kW burner scenario without the ceiling lined did not provide a severe enough test for flashover to occur with fire-retardant-treated materials. Use of the 100 and 300 kW burner scenario without lining the ceiling provided the ability to differentiate between wood products with ASTM E 84 flame spread indexes of 70 to 125 and those with higher flame spread indexes. Lining the ceiling with test material creates a more severe test.

Pyrolysis kinetics and combustion of thin wood by an advanced cone calorimetry test method

Pyrolysis kinetics analysis of extractives, holocellulose, and lignin in the solid redwood over the entire heating regime was possible by specialized cone calorimeter test and new mathematical analysis tools. Added hardware components include: modified sample holder for the thin specimen with tiny thermocouples, the methane ring burner with stainless-steel mesh above cone heater, and the water vapor sensor in heated gas sampling lines. Specialized numerical deconvolutions were applied to the oxygen and water vapor analyzer signals to synchronize with the rapid-responding CO/CO2 analyzer signals. From this data, the mass flow rates of carbon, hydrogen, and oxygen within the wood volatiles as function of time were obtained, which allowed deducing the mass flow rate of significant molecules of wood volatiles that have their origins in the wood constituents of extractives, holocellulose, and lignin. Accurate analytical solution of pyrolysis kinetics of appropriate competitive reactions that continuously conserved carbon, hydrogen, and oxygen mass flow rates was obtained for piecewise exponentially-shaped, spatially uniform temperature within the specimen as implemented conveniently in MS Excel spreadsheet.

Ignitability Analysis of Siding Materials Using Modified Protocol for Lift Apparatus

This paper reports on the ignitability of common siding materials that could be exposed to wildland fires. When exposed to brands or fires, structures will experience piloted ignition, which is requisite for sustained ignition involving burn-through and surface flame spread in various directions. In this study, the Lateral Ignition and Flame Spread Test (LIFT) apparatus (ASTM E1321 and E1317) was used to test various siding materials (plywoods, softwoods, and vinyl), some of wbich were painted, humidified, or sawed. A recently developed protocol provided useful, accurate values of the following thermophysical properties : surface emissivity, surface ignition temperature, tbermal conductivity, and thermal diffusivity. Full consistency was achieved with independent literature values of these properties and can be used directly in the database of fire growth models.