Measurement of Sub-23 nm Particles Emitted from PFI/DI SI Engine Fueled with Oxygenated Fuels: A Comparison between Conventional and Novel Methodologies

Abstract

This study focuses on the measurement of sub-23 nm particles emitted from a small DI/PFI spark ignition engine through conventional techniques and innovative systems. Measurements were performed with well-known systems, such as the EEPS coupled to a PMP-compliant sample conditioning device. Moreover, a novel instrument developed within the European project Sureal-23, the advanced HM-DMA, capable of operating with a simplified conditioning setup was used. The engine was fueled with ethanol, both pure and in blend at 30% v/v. The effects of fuel on the particle emissions were analyzed at different operating conditions. The results highlighted that a larger fraction of emissions consists of particles smaller than 23 nm, and their number changes according to the fuel, injection strategy and operating condition. A significant effect of the sampling system conditions was observed reveling the inception of nucleation mode particles or the condensation of the volatiles onto existing particles depending on the combination fuel/injection strategy. Different trends were noted at certain operating conditions between the results from the EEPS and the advanced HM-DMA ascribable to the different measurement principle and to the dilution system.

Comparison of Particle Sizers and Counters with Soot-like, Salt, and Silver Particles

“…For example, for diesel vehicles, 23 nm was considered the appropriate size, i.e., the smallest primary soot spherule [36]. Many studies, however, found particles below 23 nm for gasoline direct injection (GDI), port-fuel injection (PFI) vehicles, motorcycles, compressed natural gas (CNG) vehicles, and even diesel vehicle (e.g., urea particles) [37][38][39][40]. Furthermore, determination of the technical requirements of the instruments for on-road testing, i.e., portable emission measurement systems (PEMSs), needs an appropriate size range due to its impact to measurement uncertainty and, thus, on the definition of conformity factors [41].…”

Experimental Study With Acetone-Gasoline Fuel Blends on Engine Performance and Exhaust Emissions in a Spark Ignition Engine

“…On the contrary, compression ignition engines emit higher amount of exhaust gases such as nitrogen oxides (NOx), soot and particulate matter (PM) emissions. On the other hand, gasoline engines have advantages in view of the lower exhaust emissions, quieter operation and cheaper for initial cost [1][2][3][4][5][6][7][8][9]. However, gasoline engines need to be operated at near stoichiometric air/fuel ratios due to usage of catalytic converter.…”

“…Because compression ratio can not be increased due to auto ignition characteristics of gasoline. At this point, fuel addition into gasoline is seen to be attractive approach in order to increase the engine performance and thermal efficiency [2][3][4][5][6][7][8][9][10]. Alcohol based alternative fuels have attracted great attention in spark ignition engines due to higher octane number and oxygen content.…”

“…So, compression ratio and thermal efficiency can be increased in spark ignition engines. Besides, oxygen content of acetone is intended to improve combustion [1][2][3][4][5][6][7][8][9][10][11][12][13]. At this point, acetone can be called as an ignition improver [14].…”