Response of Real-Time Black Carbon Mass Instruments to Mini-Cast Soot

Abstract

Soot is a climate forcer and a dangerous air pollutant that has been increasingly regulated. In aviation, regulatory measurements of soot mass concentration in the exhaust of aircraft turbine engines are to be based on measurements of black carbon (BC) calibrated to elemental carbon (EC) content of diffusion flame soot. The calibration soot must currently meet only one criterion: minimum EC to total carbon (TC) ratio of 0.8. However, not including soot properties other than the EC/TC ratio may potentially lead to discrepancies between different BC measurements. We studied the response of two instruments, the AVL Micro-Soot Sensor (MSS) and the Artium Laser-Induced Incandescence 300 (LII), to soot from two miniature combustion aerosol standard (mini-CAST) burners. By changing the air-fuel ratio, premixing nitrogen into the fuel, and using a catalytic stripper to remove volatile compounds, we produced a wide range of particle morphologies and EC contents. As the EC content decreased, both the instruments underreported the EC mass, but the LII diverged more severely. Upon closer investigation of eight conditions with EC/TC > 0.8, the LII underreporting was found independent of primary particle size, but increased with decreasing geometric mean diameter of the soot agglomerates. As the geometric mean diameter decreased from 160 nm to 50 nm, the differences between the LII and MSS increased from 15% to 50%. The results suggest that in addition to EC content, calibration procedures for the regulatory BC measurements may need to take particle size distributions into account.

Department(s)

Mechanical and Aerospace Engineering

Second Department

Chemistry

Third Department

Physics

Keywords and Phrases

Aircraft Engines; Calibration; Exhaust Systems (Engine); Particle Size; Satellites; Soot; Volatile Organic Compounds; Aircraft Turbine Engines; Calibration Procedure; Combustion Aerosols; Geometric Mean Diameters; Laser Induced Incandescence; Particle Morphologies; Primary Particle Size; Regulatory Measurement; Dust

International Standard Serial Number (ISSN)

0278-6826

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2016 Taylor & Francis, All rights reserved.

Publication Date

01 Jun 2016

Link to Full Text

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