10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Nanoparticle Emissions from a Gas Engine – Effects of Gas and Lubricant Oil Composition
MIA ISOTALO, Jenni Alanen, Joonas Vanhanen, Sampsa Martikainen, Hannu Vesala, Rasmus Pettinen, Sanna Saarikoski, Minna Aurela, Pauli Simonen, Mika Kettunen, Minna Väkevä, Hilkka Timonen, Kati Lehtoranta, Jorma Keskinen, Topi Rönkkö, Tampere University of Technology
Abstract Number: 731 Working Group: Combustion
Abstract Natural gas is a promising and clean energy source and its utilization is quickly increasing. The use of other gases, such as ethane and propane, may also increase in future energy production. Biogases solely or mixed with natural gas are becoming more and more relevant. To assure the sustainable development of societies, the usage of cleaner energy sources in the future is inevitable.
Although gas engines have been thought to be a good possibility to reduce atmospheric emissions, recent studies have shown that the natural gas combustion can emit large numbers of nanoparticles (Alanen et al., 2015). For that reason, the aim of this study was to examine the nanoparticle concentrations in the fresh emission of gas engine. Two lubricant oils with different sulphur and ash content were tested to investigate the influence of lubricant oil on concentrations of nanoparticles. The effect of gas composition to the amount of emitted exhaust particles was also one objective.
The measurements were conducted in laboratory using a gasoline engine of a passenger car that has been modified to run with used fuels (natural gas and propane) before the measurement campaign (Murtonen et al., 2016). Also two different engine driving modes were used.
In this study, two different dilution systems were used. A combination of a hot ejector and an ejector dilutor was used to study primary particle emission. In delayed primary particle emission measurements, the sample went through a porous tube diluter followed by a residence time chamber and an ejector dilutor. The volatility of the particles was studied using a thermodenuder or a catalytic stripper (Amanatidis et al., 2013). Particle number concentration was measured using several condensation particle counters (TSI Inc. and Airmodus Ltd.) with different cut-points (1.3, 3 nm, 4 nm and 10 nm) and particle size magnifier (Airmodus Ltd.). In addition, particle size distributions were measured using an SMPS (TSI Inc.) and a Nano-SMPS (TSI Inc.).
The sizes of observed particles were very small with both fuels. According to the preliminary results, in the fresh exhaust emission approximately 53 % of the all observed particles (total concentration) were in the size range of 1.3–3 nm and approximately 47 % in the size range of 3–10 nm, when natural gas was used and lubricant oil contained higher amount of sulphur. The use of lubricant oil with lower sulphur content caused significant reduction in total particle number concentration and the mean size of observed particles also decreased considerably. With this oil, approximately 79 % of the all observed particles were in the size range of 1.3–3 nm and 21 % in the size range of 3–10 nm. The contribution of particles over 10 nm in size were below 1 ‰ of the total concentration. For propane, the emissions of particles were extremely low.
The financial support from Tekes (NewGas project) and from industrial partners, Wärtsilä Finland Oy, Dinex-Ecocat Oy, Dekati Oy, Neste Oyj, Oilon Oy and Airmodus Oy, is gratefully acknowledged.
[1] Alanen, J. et al. (2015) Fuel, 162, 155–161. [2] Murtonen, T. et al. (2016) CIMAC congress. [3] Amanatidis, S. et al. (2013) Journal of Aerosol Science, 57, 144–155.