Determination of PM mass emissions from an aircraft turbine engine using particle effective density

The effective density and size-resolved volatility of particles emitted from a Rolls-Royce Gnome helicopter turboshaft engine are measured at two engine speed settings (13,000 and 22,000 RPM). The effective density of denuded and undenuded particles were measured. The denuded effective densities are similar to the effective densities of particles from a gas turbine with a ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 2 double annular combustor as well as a wide variety of internal combustion engines. The denuded effective density measurements were also used to estimate the size and number of primary particles in the soot aggregates. The primary particle size estimates show that the primary particle size was smaller at lower engine speed (in agreement with transmission electron microscopy analysis). As a demonstration, the size-resolved volatility of particles emitted from the engine are measured with a system consisting of a differential mobility analyzer, centrifugal particle mass analyzer, condensation particle counter, and catalytic stripper. This system determines the number distributions of particles that contain or do not contain non-volatile material, and the mass distributions of non-volatile material, volatile material condensed onto the surface of non-volatile particles, and volatile material forming independent particles (e.g. nucleated volatile material). It was found that the particulate at 13,000 RPM contained a measurable fraction of purely volatile material with diameters below ~25 nm and had a higher mass fraction of volatile material condensed on the surface of the soot (6-12%) compared to the 22,000 RPM condition (1-5%). This study demonstrates the potential to quantify the distribution of volatile particulate matter and gives additional information to characterize sampling effects with regulatory measurement procedures.

Section: )mentioning

confidence: 59%

Section: Effective Density: Relationship Between Particle Mass and Momentioning

confidence: 99%

Section: Effective Density: Relationship Between Particle Mass and Momentioning

confidence: 99%

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Effective density and volatility of particles sampled from a helicopter gas turbine engine

Olfert

Dickau

Momenimovahed

et al. 2017

“…Also using TEM, Liati et al (2014) showed that the primary particle size of soot aggregates was dependent on the engine thrust setting; the mode of the primary particle size distribution increased from 13 to 24 nm from 7 to 100% of maximum engine thrust setting. Durdina et al (2014) showed that BC aggregate effective density is a function of engine thrust setting for a given aggregate mobility diameter and that the mass-mobility exponent ranged from 2.37 to 2.64 for 3-5% and 50-100% engine thrust settings, respectively.…”

Section: Introductionmentioning

confidence: 99%

Particle Emission Characteristics of a Gas Turbine with a Double Annular Combustor

Boies

Stettler

Swanson

et al. 2015

The total climate, air quality, and health impact of aircraft black carbon (BC) emissions depend on quantity (mass and number concentration) as well as morphology (fractal dimension and surface area) of emitted BC aggregates. This study examines multiple BC emission metrics from a gas turbine with a double annular combustor, CFM56-5B4-2P. As a part of the SAMPLE III.2 campaign, concurrent measurements of particle mobility, particle mass, particle number concentration, and mass concentration, as well as collection of transmission electron microscopy (TEM) samples, allowed for characterization of the BC emissions. Mass-and number-based emission indices were strongly influenced by thrust setting during pilot combustion and ranged from <1 to 208 mg/kg-fuel and 3 £ £ 10 12 to 3 £ £ 10 16 particles/kg-fuel, respectively. Mobility measurements indicated that mean diameters ranged from 7 to 44 nm with a strong dependence on thrust during pilot-only combustion. Using aggregation and sintering theory with empirical effective density relationships, a power-law relationship between primary particle diameter and mobility diameter is presented. Mean primary particle diameter ranged from 6 to 19 nm; however, laserinduced incandescence (LII) and mass-mobility-calculated primary particle diameters demonstrated opposite trends with thrust setting. Similarly, mass-mobility-calculated aggregate mass specific surface area and LII-measured surface area were not in agreement, indicating both methods need further development and validation before use as quantitative indicators of primary particle diameter and mass-specific surface area.

“…The CPMA classifies particles based on mass-to-charge ratio (Olfert and Collings 2005). The CPMA (or a related instrument, the aerosol particle mass analyzer, APM) has been used to measure the mass-mobility relationship of particles emitted from several engines including: diesel engines Olfert et al 2007;Barone et al 2011), natural-gasfueled homogenous-compressed charge-ignition engines (Bullock and Olfert 2014), and aircraft turbines (Durdina et al 2014;Johnson et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Characterization of Particulate Matter Morphology and Volatility from a Compression-Ignition Natural-Gas Direct-Injection Engine

Graves

Olfert

Patychuk³

et al. 2015

The particulate matter (PM) emitted from a single-cylinder compression-ignition, natural-gas engine fitted with a HighPressure Direct-Injection (HPDI) system distinctly different from a duel fuel engine was investigated, and characterized by size distribution, morphology, mass-mobility exponent, effective density, volatility, mixing state, and primary particle size using transmission electron microscopy (TEM), and tandem measurements from differential mobility analyzers (DMA) and a centrifugal particle mass analyzer (CPMA). Six engine conditions were selected with varying load, speed, exhaust gas recirculation (EGR) fraction, and fuel delivery strategy. An increase in engine load increased both the number concentration and the geometric mean diameter of the particulate. The fraction of the number of purely volatile particles to total number of particles (number volatile fraction, NVF) was found to decrease as load increased, although at the lower speed, partially premixed mode, the lowest NVF. All size distributions were also found to be unimodal. The size-segregated ratio of the mass of internally mixed volatile material to total particle mass (mass volatile fraction, MVF) decreased with load and with particle mobility-equivalent diameter. A roughly constant amount of volatile material is likely produced at each engine mode, and the decrease in MVF is due to the increase in PM number with load. Effective density and massmobility exponent of the non-volatile soot at the different engine loads were the same or slightly higher than soot from traditional diesel engines. Denuded effective density trends were observed to collapse to approximately the same line, although engine modes with higher MVFs had slightly higher effective densities suggesting that the soot structures have collapsed into more dense shapes-a suspicion that is confirmed with TEM images. TEM results also indicated that primary particle size first decreases from low to medium load, then increases from medium to high load. An increase in EGR was also seen to increase primary particle size. Coefficients were determined for a relation that gives primary particle diameter as a function of projected area equivalent diameter. A decrease in load or speed results in a stronger correlation.