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The possibility of non-volatile particle agglomeration in engine exhaust was experimentally examined in a Euro VI heavy duty engine using a variable cross section agglomeration pipe, insulated and double walled for minimal thermophoresis. The agglomeration pipe was located between the turbocharger and the exhaust treatment devices. Sampling was made across the pipe and along the centre-line of the agglomeration pipe. The performance of the agglomeration pipe was compared with an equivalent insulated straight pipe. The non-volatile total particle number and size distribution were investigated. Particle number measurements were conducted according to the guidelines from the Particle Measurement Programme. The Engine was fuelled with commercially available low sulphur S10 diesel.

In heavy-duty engines, Euro VI legislation regulates the total particle number (PN) in the exhaust based on the particle measurement program (PMP) guidelines. By PMP directives, the exhaust sample is diluted and conditioned to contain non-volatile particles before measuring the PN. The fraction of non-volatile and volatile particles changes along the exhaust after-treatment system and could affect the total PN measured. Therefore, it is of interest to compare the performance of the dilution systems at different positions along the after-treatment system. For this purpose, a standard PMP compliant two-stage dilution system (DS1) with evaporation tube (ET) was compared with a close coupled two-stage ejector dilution system (DS2). In DS2, the non-volatile PN was measured with a dilution temperature of 350°C (same as the DS1 ET temperature) while the volatile PN was measured with a dilution temperature of 150°C.

Particles emitted from internal combustion engines have adverse health effects and the severity varies based on the particle size. A diesel particulate filter (DPF) in the after-treatment systems is employed to control the particle emissions from combustion engines. The design of a DPF depends on the nature of particle size distribution at the upstream and is important to evaluate. In heavy-duty diesel engines, the turbocharger turbine is an important component affecting the flow and particles. The turbine wheel and housing influence particle number and size. This could potentially be used to reduce particle number or change the distribution to become more favourable for filtration. This work evaluates the effect of a heavy-duty diesel engine’s turbine on particle number and size distribution.

In this paper, a High-Temperature Electrical Low-Pressure Impactor (HT-ELPI+) was used to measure particles from a light-duty direct injected spark ignited (DISI) engine fueled with gasoline and ethanol. The HT-ELPI+ measured volatile and non-volatile particle emissions down to 6 nm without the need for dilution. Particle emissions were measured at four operating points while sweeping the end of injection, and at idle operation. The total particle number (PN) and particle size distribution (number and mass) for both non-volatile and volatile emissions were measured with the HT-ELPI+ and compared to the measured PN using two 71.4 times diluted Condensation Particle Counters (CPCs) with two different cut-off sizes, with 23 nm and 7 nm cut-off, respectively. The results show an increase in particle emissions in terms of particle mass and total particle number for ethanol compared to gasoline. The difference in soot mass emissions is small between the fuels.

Particle emissions from heavy-duty engines are regulated both by mass and number by Euro VI regulation. Understanding the evolution of particle size and number from the exhaust valve to the tail pipe is of vital importance to expand the possibilities of particle reduction. In this study, experiments were carried out on a heavy-duty Euro VI engine after-treatment system consisting of diesel oxidation catalyst, diesel particulate filter and selective catalytic reduction (SCR) unit with AdBlue injection followed by ammonia slip catalyst. The present work focusses on the SCR unit with regard to total particle number with and without nucleation particles both. Experiments were conducted by varying the AdBlue injection quantity, SCR inlet temperature [to vary the reaction temperature], exhaust mass flow rate [to vary the residence time in SCR], and fuel injection pressures [to vary inlet particle number and inlet NOx].