The applicability of photoacoustic measurement technique for qualitative investigation of diesel emission

In our work parallel measurement of wavelength dependent optical absorption, size distribution and number-concentration were produced using multi wavelength photoacoustic spectrometer (4λ-PAS) and scanning mobility particle sizer (SMPS). For comparative study two different fuel type was tested at three different working points of the engine. The thermal evolution of the emission was also examined using thermodenuder (TD) unit. Bimodal size distribution of emissions at reference temperature was achieved using pure petroleum-based fuel (B0). The OAC values measured at the operating wavelengths of the instrument decreased with increasing rev and rated torque at all wavelengths. The wavelength dependence quantified by Aerosol Angström Exponent (AAE) can be used here for qualitative analysis of carbon emission and showed increased volatility of organic particles towards higher temperatures

Robottechnikai eszközök fedett lézeres kommunikációja: doktori (PhD) értekezés

Bibliogr.: fol. 158-173.Publikációs jegyzék: fol. 174.Ábrák, táblázatok és képek jegyzéke: fol. 176-182.A 2 db melléklet a disszertáció magyar és angol nyelvű tézisfüzeteit tartalmazzaNemzeti Közszolgálati Egyetem. Budapest, Hadtudományi és Honvédtisztképző Kar, Katonai Műszaki Doktori Iskol

The investigation of diesel soot emission using instrument combination of multi-wavelength photoacoustic spectroscopy and scanning mobility particle sizer

Abstract The parallel measurements of wavelength dependent optical absorption, particle number size distribution have made by a multi wavelength photoacoustic spectrometer (4λ-PAS) and scanning mobility particle sizer (SMPS) respectively at different modes of a diesel engine using two different types of fuel. The thermal evolution of the emission was also investigated using posterior temperature treatment of emission. The bimodal size distribution of emitted particles at a set reference temperature has been observed regardless of the applied fuel at idle. However, the emitted particulate assembly had lognormal size distribution falls into the accumulation mode at all other defined engine modes and both fuel types. The total number- and volume concentration (TNC and TVC) showed retrograde tendency with the increasing torque and rpm independently of the applied fuel types. The TNC values decreased up to 50% for both fuels with engine operation changes from idle engine mode(em#1) to low engine mode(em#2). With further increase in torque and rpm of engine, the change in TNC is negligible. On the other hand, the TVC remains more or less the same for idle to low engine mode transition and increased more than 60% for high mode (em#3) transition. The Optical Absorption Coefficient (OAC) values measured at the operational wavelengths of the 4λ-PAS instrument decreased at all wavelengths with increasing rpm and torque. The wavelength dependency quantified by Aerosol Ängström Exponent (AAE) was applied here for qualitative analysis of the carbonaceous emission and showed decreased values towards the higher engine speed and torque output of the engine. The proposed technique can be used as real-time, precise and accurate measurement of light absorption by DPM aerosols, which opens up novel possibilities for the volatility and thermal evolution investigation of diesel emissions