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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - PEMs4Nano (Portable Nano-Particle Emission Measurement System)

Teaser

Summary

The PEMs4Nano project (PEMs4Nano) addresses the development (based on current direct injection gasoline engines) of measurement procedures down to 10nm particle size, providing a contribution to future regulation on particle emissions, in particular in real driving conditions. The activities planned in the project will also support the understanding, measurement and regulation of particle emissions below 23 nm (with the threshold of 10 nm).

Two measurement systems based on current technologies will be optimized for use in the development laboratory and for mobile testing. Physico-chemical and data-driven simulations combined with optimization is proposed to establish valuable correlations between measurements made in the development laboratory and thus finally those measured on the road.

PEMs4nano thus proposes a two-path approach that connects tailpipe measurements with the origin and the evolution of the particles, resulting in a seamless approach from the laboratory to the field test capabilities. Investigations of particle characteristics (incl. composition, size and morphology) and their influence on successful measurements will also be carried out using various load profiles that make up real-driving to validate the application of the measurement procedure.

The overall objectives of the PEMs4Nano are:
1. Developing robust and reliable measurement procedures for particles down to 10 nm and verified under real driving conditions, including a solid particle counting system for measurements in the laboratory and a portable emission measurement system for on the road.
2. Fundamental understanding of the particle formation, composition, size distribution and transport and the impact to the measurement procedure, including a simulation platform.
3. Demonstrate and evaluate the application and measurement technology.

Work performed

At the start of the project, the partners have quantified and agreed on the specifications regarding specific performance values or ranges, or boundary conditions that are relevant for the actual measurements in the laboratory or in the field. These criteria are key to obtaining reliable measurement protocols at the end of the projects, and have been defined in the first months of the project.

A CPC engine for measurements of PEMS PN vehicle emissions with particle sizes larger than 23 nm was optimized for the use in a PEMS PN detecting particles of 10 nm. The optimization could be achieved by changing the operating temperatures and the coefficients. It was demonstrated in calibration measurements that a particle detection efficiency (D50) less than 10 nm for â€œsoot-likeâ€ particles could be achieved.

Analytical techniques were developed to characterize the emitted particles. Data was collected using size-selective collection instruments (Nano-DMA, nanoMOUDI), atomic resolution analytical methods (AFM, SEM, TEM) and mass spectrometric techniques (L2MS, SIMS). The particle size and surface chemistry (and thus source) of the particles could be characterized and linked to different engine working points. The size-dependent chemical composition of particulate matter could be described in detail, including particle sources (combustion versus secondary particle sources) and a direct link to fuel and lubricant raw composition or combustion products. These analyses provide essential chemical composition data (especially concerning adsorbed hydrocarbons (soluble organic fraction), aromatics, metals (ash) and sulfur-bearing species) for future integration into the simulation models.

Regarding these simulation models, a novel particulate formation model that includes a description of liquid-like particles has been formulated and implemented into the (Stochastic Reactor Model) SRM Engine Suite software. The coupled software is validated against measurements data from a single cylinder research engine at Bosch for in-cylinder pressure, gas phase emissions and particle phase emissions over a range of engine loads and speeds. Furthermore, the effect of the sampling system conditions on the evolution of the predicted engine-out particle size distributions and composition is investigated using chemical reactor networks.

PEMs4Nano was represented at the Transport and Research Arena in Vienna, where there was significant attention for the project.

Final results

The current technology is based upon the method developed by the Particle Measurement Program (PMP) for measuring of particles emitted originally from diesel-fuelled light duty vehicles. This method is based on counting solid (non-volatile) particles with a size above 23 nm. The progress beyond the state-of-the-art in PEMs4Nano is to deliver measurement technology and procedures that allow the existing Type Approval systems to be modified should the size range for legislation be reduced to 10nm at some point in the future.

To achieve this, PEMS4Nano will develop the technology to reliably measure particles down to 10nm. Optimised condensation particle counters (CPCs) will be developed for laboratory PN measurement and for on-board vehicle for Real Driving PN emissions to reliably count particles down to at least 10 nm in diameter. A catalytic stripper (CS) will be introduced to remove the volatile components, and particle losses in the CS will be investigated and minimized. Finally, the calibration will be optimized and validated to enable robust and reliable measurement procedures for particle sizes down to 10 nm.

Another key innovation is to develop a fundamental understanding. The partners will characterize the particle formation, composition, size distribution and transport in detail. Also, the particulate emissions in IC engine driven vehicles will be simulated using model-guided application (MGA), an approach that combines physico-chemical and statistical algorithms. Existing particle formation models are not well-suited to modelling PM and PN emissions from modern vehicles, and the MGA aims to address this technology gap. The results are used to understand how variations will influence the measurement procedures, and (once validated) reduce the need for broad and extensive measurements.

The impact will be the know-how to accurately measure particle emissions of direct injection gasoline engines in stationary and real driving conditions, and the understanding of particle emissions below 23 nm (with the threshold of 10 nm). Understanding how particles are formed supports the development of future new more efficient engine and aftertreatment technologies, and supports new regulations due to the capability to detect emissions of particles down to 10 nm in size that are now undetected by current certification procedures.

In a broader perspective, these innovations will significantly contribute to reducing particle emissions from vehicles (transport sector). Reduced particle emissions will contribute to human health; the improvement of the air quality is especially important in urban environments and for the millions of people living in close vicinity of major roads. And finally, PEMs4Nano contributes to the employment in the emission measurement technology sector and contribute to improved working conditions for outdoor workers, especially in cities and in the road infrastructure maintenance sector.