Abstract
Introduction: Laser-Induced Incandescence (LII) is an established technology in science for studying soot in flames and aerosols. Its capability of measuring at high time resolution with accuracies meeting legally mandated limits renders it of high interest also for measuring soot concentrations in automotive exhausts. This work presents the first attempt to realise a highly compact in-situ LII system applicable directly at an automotive exhaust pipe.
Experimental Methods: Key components for the proposed in-situ LII system are a super-compact high-power DPSS laser (CTR HiPoLas®), fast KETEK silicon photomultipliers (SiPM) as detectors and a dedicated optical measurement setup. A measurement cell was specially designed for i) optimized collection of the incandescent radiation and ii) high flexibility, to allow verifying LII both with different aerosols from particle generators (e.g. Jing 5201 miniCAST – Combustion Aerosol STandard) and automotive exhausts from an engine testbed.
Results: Measurements using aerosol from the CAST proved the incandescence signals to be clearly distinguishable from scattered laser light and yielded corresponding LII signals, proving the fundamental feasibility of an in-situ LII probe. It thus appears very likely that previously used extractive cells and large-scale laser sources can be replaced by this approach, providing a true in-situ particle sensor. Further testing is ongoing, as are the tests with real automotive exhausts. Efforts now focus in particular on providing a calibration of the LII signals in dependence on the soot concentration using a CAST, and evaluate the applicability of this calibration for the use on exhaust gases.
Experimental Methods: Key components for the proposed in-situ LII system are a super-compact high-power DPSS laser (CTR HiPoLas®), fast KETEK silicon photomultipliers (SiPM) as detectors and a dedicated optical measurement setup. A measurement cell was specially designed for i) optimized collection of the incandescent radiation and ii) high flexibility, to allow verifying LII both with different aerosols from particle generators (e.g. Jing 5201 miniCAST – Combustion Aerosol STandard) and automotive exhausts from an engine testbed.
Results: Measurements using aerosol from the CAST proved the incandescence signals to be clearly distinguishable from scattered laser light and yielded corresponding LII signals, proving the fundamental feasibility of an in-situ LII probe. It thus appears very likely that previously used extractive cells and large-scale laser sources can be replaced by this approach, providing a true in-situ particle sensor. Further testing is ongoing, as are the tests with real automotive exhausts. Efforts now focus in particular on providing a calibration of the LII signals in dependence on the soot concentration using a CAST, and evaluate the applicability of this calibration for the use on exhaust gases.
| Original language | English |
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| Publication status | Published - 18 Sept 2017 |
| Event | 36th AAAR Annual Conference - Raleigh Convention Center, Raleigh, North Carolina, United States Duration: 16 Oct 2017 → 20 Oct 2017 https://www.aaar.org/2017/ |
Conference
| Conference | 36th AAAR Annual Conference |
|---|---|
| Country/Territory | United States |
| City | Raleigh, North Carolina |
| Period | 16/10/17 → 20/10/17 |
| Internet address |