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Particulate matter measurement in a shock tube facility under engine-relevant conditions

University of British Columbia

This study develops and demonstrates a particulate matter (PM) measurement system in a shock tube facility, in order to investigate correlations between PM emissions and combustion parameters. The resultant method was applied to premixed and non-premixed experiments using several diesel-alternative gaseous fuel mixtures. As the main component of shock tube PM , soot formation mechanisms are highly complex. The sampling methodology evolution considered technical challenges in experimental conditions attainment, contamination control, particle loss minimization, and proper instrument detection. The key resultant sampling system apparatus and procedures include conductive surfaces, particle impaction, and tube settling. Consistent background black carbon (BC) levels of 100-150 ng have been achieved in blank tests. Significant particle losses through visible BC mass increment curve decay have also been eliminated for both blank and injection experiments. Aethalometer data analysis algorithms are modified to suit the needs and limitations of this novel experimental setup. The preliminary results under engine-relevant conditions show the promise of methane/natural gas in meeting the 2007 standards. The limited set of premixed experiments (using methane and methane/ethane) did not produce noticeable BC trends with combustion temperature, pressure, or equivalence ratio (EQR). Non-premixed experiments with a gaseous fuel (using methane/DME, methane, and methane/ethane blends) injector also lacked clear dependences on temperature or pressure. Larger experimental sets of low EQR premixed and higher fuel mass injections should produce meaningful results. Dominant errors are due to particle loss and optical specific attenuation uncertainties. External measurement validation and shot-to-shot variability must be studied for proper BC signal interpretation. It is extremely challenging to achieve accurate and repeatable global BC mass measurements from methane flames in a shock tube. Any future work to build upon the current sampling system and methodology should be carefully approached.

Text

2011-02-17

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http://hdl.handle.net/2429/31417

Mechanical Engineering

University of British Columbia

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