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Fossil fuel combustion should be decreased in future years in order to lower the CO2 emissions of energy production. The reduction can be achieved by increasing the amount of CO2-neutral fuels in energy production. Here 6–13% of coal was substituted with industrial or roasted pellets in a pulverized fuel-fired power plant without making any changes to fuel grinding or low-NOx burners. The effect of pellet addition for the flue gas particles was studied with direct sampling from the boiler super heater area. Based on primary dilution ratio tests, transmission electron microscope images, and the natural electric charge of the particles, it was observed that particles in the flue gas are spherical and have been formed in the boiler at high temperatures. The pellet addition lowered the total particle number concentrations with all of the studied pellet–coal mixtures in comparison to the coal combustion. The 10.5% industrial pellet addition caused a second mode in the particle number size distribution. In addition, based on the chemical analysis of the collected size-fractioned particle samples, results indicated that the pellet addition did not increase the corrosion risk of the boiler. However, the changes in the particle number size distribution and total particle number concentration can affect the operation of electrostatic precipitators and flue gas cleaning. ; publishedVersion ; Peer reviewed

The latest generation of internal combustion engines may emit significant levels of sub-23 nm particles. The main objective of the Horizon 2020 "DownToTen"project was to develop a robust methodology and provide policy recommendations towards the particle number (PN) emissions measurements in the sub-23 nm region. In order to achieve this target, a new portable exhaust particle sampling system (PEPS) was developed, being capable of measuring exhaust particles down to at least 10 nm under real-world conditions. The main design target was to build a system that is compatible with current PMP requirements and is characterized by minimized losses in the sub-23 nm region, high robustness against artefacts and high flexibility in terms of different PN modes investigation, i.e. non-volatile, volatile and secondary particles. This measurement setup was used for the evaluation of particle emissions from the latest technology engine and powertrain technologies (including vehicles from other Horizon 2020 projects), different fuel types, and a wide range of exhaust aftertreatment systems. Results revealed that in most cases (non-volatile), PN emissions down to 10 nm (SPN10) do not exceed the current SPN23 limit of 6×1011 p/km. However, there are some cases where SPN10 emissions exceeded the limit, although SPN23 were below that. An interesting finding was that even in the latter cases, the installation of a particle filter could significantly reduce PN emissions across a wide particle size range, fuels, and combustion technology. DownToTen results are being used to scientifically underpin the Euro 7/VII emission standard development in the EU. The method developed and the results obtained may be used to bring in the market clean and efficient vehicle technologies, improve engine and emission control performance with different fuels, and characterize size-fractionated particle chemistry to identify the formation mechanisms and control those in a targeted, cost-effective fashion. ; acceptedVersion ; Peer reviewed

Current legislations typically characterize systems of aerosols, such as from vehicle exhaust, primarily by number concentration and size distributions. While potential health threats have a dependence on the particle size, the chemical composition of particles, including the volatile and semi-volatile components adsorbed onto nonvolatile particle cores present at roadside and urban settings, is important in understanding the impact of exhaust particles on health. To date, the only tools suitable for an online in-depth chemical aerosol characterization are aerosol mass spectrometers, which are typically composed of complex and cost intensive instrumentation. We present a new analytical system, which combines a novel inexpensive infrared-radiation-based evaporation system (HELIOS) with a commercially available highly efficient atmospheric ionization source (SICRIT) connected to a rather low-price ion-trap mass spectrometer. Our inexpensive, robust and mobile aerosol characterization HELIOS/SICRIT/Mass Spectrometry system enables highly sensitive chemical analysis of particle-associated volatile substances. We validate the HELIOS/SICRIT/Mass Spectrometry system in laboratory experiments with coated particles generated under controlled conditions, and show that the system is capable of identification of combustion-generated polycyclic aromatic hydrocarbons and relative quantification of individual chemical species adsorbed on particle surfaces. We then employ our system to analyze real-world vehicle engine exhaust aerosol and show through time-resolved measurements with high time resolution (<10 s) that the chemical composition of the particles changes during different parts of an engine test cycle. ; acceptedVersion ; Peer reviewed