Predictive Model Development for Aviation Black Carbon Mass Emissions from Alternative and Conventional Fuels at Ground and Cruise

Abstract

The first order approximation (FOA3) currently employed to estimate BC mass emissions underpredicts BC emissions due to inaccuracies in measuring low smoke numbers (SNs) produced by modern high bypass ratio engines. The recently developed Formation and Oxidation (FOX) method removes the need for and hence uncertainty associated with (SNs), instead relying upon engine conditions in order to predict BC mass. Using the true engine operating conditions from proprietary engine cycle data an improved FOX (ImFOX) predictive relation is developed. Still, the current methods are not optimized to estimate cruise emissions nor account for the use of alternative jet fuels with reduced aromatic content. Here improved correlations are developed to predict engine conditions and BC mass emissions at ground and cruise altitude. This new ImFOX is paired with a newly developed hydrogen relation to predict emissions from alternative fuels and fuel blends. The ImFOX is designed for rich-quench-lean style combustor technologies employed predominately in the current aviation fleet.

Particle emissions of two unblended alternative jet fuels in a full scale jet engine

“…The particle mass concentration at the exit plane can be estimated via different generic models for turboshaft engines. We applied the imFOX model [30] and the FOA3 model [31] to the reference kerosene runs ( Figure SI4).…”

Nonvolatile Particulate Matter Emissions of a Business Jet Measured at Ground Level and Estimated for Cruising Altitudes

“…3,4,[7][8][9][10][11] Due to their potential health and climate impacts, various research programs have focused on characterization of particle emissions from aircraft engines, development of measurement techniques and predictive models for estimating aviation nvPM emissions. [12][13][14][15][16][17] Recent research has been motivated also by the development of a certification standard for nvPM emissions of new commercial aircraft turbine engines. [18][19][20][21][22] The International Civil Aviation Organization 55 (ICAO) has adopted the nvPM standard that applies to all engine types rated >26.7 kN thrust in 56 production on or after 1 January 2020.…”

A number-based inventory of size-resolved black carbon particle emissions by global civil aviation

“…The estimated LTO mass emission is comparable with the data in AEIC-FOA3 (0.6 Gg) and EDGAR (0.6 Gg) inventories, but significantly smaller than that in AEIC-FOX (2.4 Gg). The recent studies 27,44 indicated that the FOX method might overestimate the BC mass emission by up to a factor of 4. The estimated CCD emission is also in line with the data in EDGAR (8.4 Gg), but the differences are relatively large compared with the AEIC estimations by FOA3 (1.4 Gg) and FOX (14.5 Gg) methods, which is assumed to be caused by the different adopted engine fuel flows at cruise 26 .…”

“…Due to the paucity of BC particle emission data in the ICAO (International Civil Aviation Organization) Emission Databank (EDB) 19 , majority of the currently commonly utilized global aviation emission inventories 20–23 only contain gaseous emissions including unburnt hydrocarbons (HC), carbon monoxide (CO) and oxides of nitrogen (NO x ). Many studies tried to correlate the BC mass emission with the current regulatory metric Smoke Number (SN), including the SN dependent First Order Approximation (FOA1.0 to FOA3.0) methods 24,25 , the semi-empirical SN independent Formation OXidation methods FOX 26 and imFOX 27 , and the scaling methods for the cruise emissions 28 . The emergence of these methods led to the developments of BC mass emission inventories, e.g., AERO2k 29 , AEIC 26 , and AEDT 30 .…”