Particulate Morphology Characterization of Butanol–Gasoline Blend Fueled Spark-Ignition Direct Injection Engine

2020 ◽  
Vol 142 (10) ◽  
Author(s):  
Nikhil Sharma ◽  
Avinash Kumar Agarwal

Abstract Butanol is an oxygenated renewable fuel and therefore is a potential candidate to be blended with gasoline to reduce particulate emissions. In this experimental investigation, particle number-size (PN-size) distribution and morphology (physical characterization) of soot emitted by the butanol–gasoline blend in a gasoline direct injection (GDI) engine have been investigated. The effect of engine load and fuel injection pressure (FIP) on particulates was investigated for two test fuels: gasoline and Bu15 (85%, v/v, gasoline blended with 15%, v/v, butanol) in a 0.5 L single-cylinder GDI engine using an engine exhaust particulate sizer (EEPS) and a partial flow dilution tunnel for collecting particulate samples on a filter paper. The physical characterization of particulates included primary particle size (Dp) and particle agglomerate characterization parameters such as agglomerate length (L), agglomerate width (W), skeletal length (Lsk) and skeletal width (Wsk), which were determined using a transmission electron microscope (TEM) and corresponding image analyses. PN-size distribution was relatively lower for Bu15, which decreased with increasing FIP. Regardless of the GDI engine operating condition, classical sphere and chain-like agglomerates having nearly similar nano-scale morphology were detected. The primary particle diameter changed with varying engine operating conditions. A comparative analysis of soot originating from Bu15 and gasoline was presented, which may be useful for gasoline particulate filter (GPF) design and to understand the regeneration of GPFs in practical engine applications.

Author(s):  
Sandeep Viswanathan ◽  
Stephen S. Sakai ◽  
Mitchell Hageman ◽  
David E. Foster ◽  
Todd Fansler ◽  
...  

The exhaust filtration analysis system (EFA) developed at the University of Wisconsin – Madison was used to perform micro-scale filtration experiments on cordierite filter samples using particulate matter (PM) generated by a spark-ignition direct injection (SIDI) engine fueled with gasoline. A scanning mobility particle sizer (SMPS) was used to characterize running conditions with four distinct particle size distributions (PSDs). The distributions selected differed in the relative number of accumulation versus nucleation mode particles. The SMPS and an engine exhaust particle sizer (EEPS) were used to simultaneously measure the PSD downstream of the EFA and the real-time particulate emissions from the SIDI engine to determine the evolution of filtration efficiency during filter loading. Cordierite filter samples with properties representative of diesel particulate filters (DPFs) were loaded with PM from the different engine operating conditions. The results were compared to understand the impact of particle size distribution on filtration performance as well as the role of accumulation mode particles on the diffusion capture of PM. The most penetrating particle size (MPPS) was observed to decrease as a result of particle deposition within the filter substrate. In the absence of a soot cake, the penetration of particles smaller than 70 nm was seen to gradually increase with time, potentially due to increased velocities in the filter as flow area reduces during filter loading, or due to decreasing wall area for capture of particles by diffusion. Particle re-entrainment was not observed for any of the operating conditions.


Author(s):  
Brandon A. Sforzo ◽  
Aniket Tekawade ◽  
Alan L. Kastengren ◽  
Kamel Fezzaa ◽  
Jan Ilavsky ◽  
...  

Abstract The effects of fuel blend properties on spray and injector performance has been investigated for several operating conditions in a side-mount injector for Gasoline Direct Injection (GDI) using two certification fuel blends, Euro 5 and Euro 6. Several X-ray diagnostic techniques were conducted to characterize the injector and spray morphology. Detailed internal geometry of the GDI injector was measured with a feature-resolution of 1.8 micrometers, through the use of hard X-ray tomography. The geometry characterization of this six-hole GDI, side mount injector, quantifies relevant hole and counterbore dimensions and reveals the intricate details within the flow passages, including surface roughness and micron-sized features. Internal valve motion was measured with a temporal resolution of 20 microseconds and a spatial resolution of 2.0 micrometers, for three injection pressures and several injector energizing strategies. The needle motion for both fuels exhibit similar lift profiles for common energizing commands. A combination of X-ray radiography and Ultra-Small-Angle X-ray Scattering (USAXS) was used to characterize the fuel mass distribution and the droplet sizing, respectively. Tomographic spray radiography revealed the near-nozzle distribution of fuel mass for each of the fuels, and the asymmetry produced by the angled nozzles. Under evaporative conditions, the two fuels show minor differences in peak fuel mass distribution during steady injection, though both exhibit fluctuations in injection during the early, transient phase. US-AXS measurements of the path-specific surface area of the spray indicated lower peak values for the more evaporative conditions in the near nozzle region. These spray measurements portray the specific behavior of real fuel blends under a variety of conditions, illustrating the need to examine multi-component fuels to better understand relevant cases. Furthermore, this work furnishes the realistic boundary values for simulations to appropriately predict the sprays which were experimentally measured, and influenced by those realistic conditions.


Author(s):  
Sandeep Viswanathan ◽  
David Rothamer ◽  
Stephen Sakai ◽  
Mitchell Hageman ◽  
David Foster ◽  
...  

The exhaust filtration analysis system (EFA) developed at the University of Wisconsin–Madison was used to perform microscale filtration experiments on cordierite filter samples using particulate matter (PM) generated by a spark ignition direct injection (SIDI) engine fueled with gasoline. A scanning mobility particle sizer (SMPS) was used to characterize running conditions with four distinct particle size distributions (PSDs). The distributions selected differed in the relative number of accumulation versus nucleation mode particles. The SMPS and an engine exhaust particle sizer (EEPS) were used to simultaneously measure the PSD downstream of the EFA and the real-time particulate emissions from the SIDI engine to determine the evolution of filtration efficiency (FE) during filter loading. Cordierite filter samples with properties representative of diesel particulate filters (DPFs) were loaded with PM from the different engine operating conditions. The results were compared to understand the impact of PSD on filtration performance as well as the role of accumulation mode particles on the diffusion capture of PM. The most penetrating particle size (MPPS) was observed to decrease as a result of particle deposition within the filter substrate. In the absence of a soot cake, the penetration of particles smaller than 70 nm was seen to gradually increase with time, potentially due to increased velocities in the filter as flow area reduces during filter loading, or due to decreasing wall area for capture of particles by diffusion. Particle re-entrainment was not observed for any of the operating conditions.


Author(s):  
Om Parkash Bhardwaj ◽  
Bernhard Lüers ◽  
Andreas F. Kolbeck ◽  
Thomas Koerfer ◽  
Florian Kremer ◽  
...  

In recent years a lot of effort has been made to understand the phenomena of Diesel Particulate Filter (DPF) regeneration processes but less attention has been paid to understand the influence of fuel properties on soot reactivity and its consequence on the DPF regeneration behavior. Within the Cluster of Excellence “Tailor-Made Fuels from Biomass (TMFB)” at RWTH Aachen University, the Institute for Combustion Engines carried out a detailed investigation program to explore the potential of future biofuel candidates for optimized combustion systems. These new biofuels are being developed to realize partially homogeneous low-temperature combustion, in order to reduce the emission and fuel consumption to meet future requirements. The chemical structure of these new fuels may impact the thermal decomposition chemistry and hence the in-cylinder particulate formation conditions. This work fundamentally focusses the influence of fuel properties on particulate matter reactivity and, thereby, the regeneration behavior of the diesel particulate filters (DPF). The experiments for particulate measurements and analysis were conducted, under constant engine operating conditions, on a EURO 6 compliant High Efficiency Combustion System (HECS) fuelled with petroleum based diesel fuel as baseline and today’s biofuels like FAME and Fischer Tropsch fuels as well as potential biomass derived fuel candidates being researched in TMFB. Several different methods were used for analysis of mass, composition, structure and spectroscopic parameters of the soot. The graphitic microstructure visible with high resolution transmission electron microscopy (HRTEM) was compared to the results of X-Ray diffraction (XRD), optical light absorption measurement and elementary analysis of samples. The results indicate that combustion with increasing fuel oxygenation produces decreasing engine-out particulate emissions. The ranking of activation energies of soot oxidation analysis from LGB experiments correspond well with the ranking of the soot physico-chemical properties. In comparison to petroleum based diesel fuel, the reduction of engine out soot emission by a factor of five with the use of the future biomass derived fuel candidate was accompanied by ten times reduction of the soot volume based absorption coefficient and two times reduction of carbon to hydrogen ratio. As a result of it, the activation energy of soot oxidation in DPF reduced by ∼ 10 KJ/mol. The reduced engine out soot emission and increased reactivity of the soot from the future biomass derived fuel candidate could cause a significant reduction of thermal DPF regenerations.


2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Nikhil Sharma ◽  
Rashmi A. Agarwal ◽  
Avinash Kumar Agarwal

Direct injection spark ignition or gasoline direct injection (GDI) engines are superior in terms of relatively higher thermal efficiency and power output compared to multipoint port fuel injection engines and direct injection diesel engines. In this study, a 500 cc single cylinder GDI engine was used for experiments. Three gasohol blends (15% (v/v) ethanol/methanol/butanol with 85% (v/v) gasoline) were chosen for this experimental study and were characterized to determine their important fuel properties. For particulate investigations, exhaust particles were collected on a quartz filter paper using a partial flow dilution tunnel. Comparative investigations for particulate mass emissions, trace metal concentrations, Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) analyses, and high-resolution transmission electron microscopy (HR-TEM) imaging of the particulate samples collected from different test fuels at different engine loads were performed. For majority of the experimental conditions, gasohols showed relatively lower trace metal concentration in particulates compared to gasoline. HR-TEM images showed that higher engine loads and presence of oxygen in the test fuels increased the soot reactivity. Multicore shells like structures were visible in the HR-TEM images due to growth of nuclei, and rapid soot formation due to relatively higher temperature and pressure environment of the engine combustion chamber. Researches world-over are trying to reduce particulate emissions from GDI engines; however there is a vast research gap for such investigations related to gasohol fueled GDI engines. This paper critically assesses and highlights comparative morphological characteristics of gasohol fueled GDI engine.


2021 ◽  
pp. 1-19
Author(s):  
Nikhil Sharma ◽  
Avinash Kumar Agarwal

Abstract Optimized fuel injection timings in internal combustion (IC) engines exhibit superior performance, combustion characteristics, and lower emissions. Particularly, particulate emissions from a gasoline direct injection (GDI) engine are highly dependent on fuel injection timings. GDI engines have emerged as a popular choice of powerplants for automobiles among customers. They are preferred over multiple-port fuel injection (MPFI) engines in the transport sector because of their superior fuel economy and performance characteristics. The main objective of this study was to optimize a GDI engine for the lowest particulate emission at different fuel injection timings. GDI engine was investigated for particulate matter (PM) mass/ particulate number (PN) emissions at five fuel injection timings (230, 250, 270, 290, 310 °btdc), which covered the entire envelope. Once the optimum fuel injection timing was determined, an engine exhaust particle sizer was used to measure the particle size-number distribution. Particulate samples from the engine were also collected on the filter paper for morphological investigations of particulates collected under optimized fuel injection timings. These experiments confirmed the importance and need to optimize the fuel injection timings at every engine operating point to reduce the PM/PN emissions from a GDI engine, which remains one of the biggest challenges to this technology.


Author(s):  
C Tornatore ◽  
S S Merola ◽  
B M Vaglieco

The aim of this work is the characterization of the emissions of exhaust particles in terms of number size distribution and chemical—physical properties. Laser-induced incandescence and broadband ultraviolet—visible extinction and scattering spectroscopy were used at the exhaust of a common-rail diesel engine and of a port fuel injection (PFI) spark ignition (SI) engine. The optical results were compared with size distributions obtained with an electrical low-pressure impactor and a scanning mobility particle sizer. Moreover, the fundamental engine parameters and the particulate mass and gas concentrations were measured using conventional instrumentation. With respect to the diesel engine, the effect of the exhaust after-treatment was investigated. The exhaust gas recirculation influenced the particle size distribution in terms of number concentration owing to the formation of accumulation mode particles. The catalysed diesel particulate filter strongly reduced the particle number concentration in the loading phase. Effects on the chemical nature of the particles were observed during the filter regeneration phase. With respect to the PFI SI engine, high number concentrations of nanoparticles ( D<50nm) were measured for all the engine operating conditions. The chemical nature of the nanoparticles was investigated.


2020 ◽  
pp. 146808742097389
Author(s):  
Fahad M Alzahrani ◽  
Mohammad Fatouraie ◽  
Volker Sick

Unevaporated fuel films forming on the fuel injector tip of gasoline direct-injection engines burn in a diffusion flame at the time of spark, producing particulates and at some operating conditions, these films have been identified as the dominating source of particulate emissions. This work developed an analytical model for liquid film evaporation on the injector tip, that is, injector tip drying, for the mitigation of injector tip wetting and the resulting particulate emissions. The model explains theoretically how fuel films on the injector tip evaporate with time from the end of injection to the spark. The model takes into consideration engine operating conditions, including engine load and speed, tip and fuel temperatures, gas temperature and pressure, and fuel properties. The model explains the observed trends in particulate number (PN) emissions due to injector tip wetting. Engine experiments were used to validate the model by correlating the predicted film mass at the time of spark to measurements of PN emissions at different conditions. A tip drying time constant was also defined and was found to correlate well with the measured PN for all conditions tested. This time constant is a deterministic factor for mitigating tip wetting. In general, the results indicate that the liquid film evaporation on the injector tip follows a first order, asymptotic behavior. Furthermore, the tip drying physics causes the observed increasing and decreasing non-linear trends in PN emissions with the engine load and the available time for tip drying, respectively. Additionally, the liquid film evaporation on the injector tip is highly sensitive to most of the injector initial and boundary conditions, including the initial film mass after the end of injection, the wetted surface area, the available time for tip drying and the injector tip temperature. The initial film temperature has the least effect on film mass evaporation.


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