Tak W. Chan

Black Carbon Emissions in Gasoline Exhaust and a Reduction Alternative with a Gasoline Particulate Filter

Black carbon (BC) mass and solid particle number emissions were obtained from two pairs of gasoline direct injection (GDI) vehicles and port fuel injection (PFI) vehicles over the U.S. Federal Test Procedure 75 (FTP-75) and US06 Supplemental Federal Test Procedure (US06) drive cycles on gasoline and 10% by volume blended ethanol (E10). BC solid particles were emitted mostly during cold-start from all GDI and PFI vehicles. The reduction in ambient temperature had significant impacts on BC mass and solid particle number emissions, but larger impacts were observed on the PFI vehicles than the GDI vehicles. Over the FTP-75 phase 1 (cold-start) drive cycle, the BC mass emissions from the two GDI vehicles at 0 °F (-18 °C) varied from 57 to 143 mg/mi, which was higher than the emissions at 72 °F (22 °C; 12-29 mg/mi) by a factor of 5. For the two PFI vehicles, the BC mass emissions over the FTP-75 phase 1 drive cycle at 0 °F varied from 111 to 162 mg/mi, higher by a factor of 44-72 when compared to the BC emissions of 2-4 mg/mi at 72 °F. The use of a gasoline particulate filter (GPF) reduced BC emissions from the selected GDI vehicle by 73-88% at various ambient temperatures over the FTP-75 phase 1 drive cycle. The ambient temperature had less of an impact on particle emissions for a warmed-up engine. Over the US06 drive cycle, the GPF reduced BC mass emissions from the GDI vehicle by 59-80% at various temperatures. E10 had limited impact on BC emissions from the selected GDI and PFI vehicles during hot-starts. E10 was found to reduce BC emissions from the GDI vehicle by 15% at standard temperature and by 75% at 19 °F (-7 °C).

Measurements of gas phase acids in diesel exhaust: a relevant source of HNCO?

Gas-phase acids in light duty diesel (LDD) vehicle exhaust were measured using chemical ionization mass spectrometry (CIMS). Fuel based emission factors (EF) and NOx ratios for these species were determined under differing steady state engine operating conditions. The derived HONO and HNO3 EFs agree well with literature values, with HONO being the single most important acidic emission. Of particular importance is the quantification of the EF for the toxic species, isocyanic acid (HNCO). The emission factors for HNCO ranged from 0.69 to 3.96 mg kgfuel(-1), and were significantly higher than previous biomass burning emission estimates. Further ambient urban measurements of HNCO demonstrated a clear relationship with the known traffic markers of benzene and toluene, demonstrating for the first time that urban commuter traffic is a source of HNCO. Estimates based upon the HNCO-benzene relationship indicate that upward of 23 tonnes of HNCO are released annually from commuter traffic in the Greater Toronto Area, far exceeding the amount possible from LDD alone. Nationally, 250 to 770 tonnes of HNCO may be emitted annually from on-road vehicles, likely representing the dominant source of exposure in urban areas, and with emissions comparable to that of biomass burning.

Nitrogen Dioxide and Ultrafine Particles Dominate the Biological Effects of Inhaled Diesel Exhaust Treated by a Catalyzed Diesel Particulate Filter

We studied the impact of a catalyzed diesel particulate filter (DPF) on the toxicity of diesel exhaust. Rats inhaled exhaust from a Cummins ISM heavy-duty diesel engine, with and without DPF after-treatment, or HEPA-filtered air for 4h, on 1 day (single exposure) and 3 days (repeated exposures). Biological effects were assessed after 2h (single exposure) and 20h (single and repeated exposures) recovery in clean air. Concentrations of pollutants were (1) untreated exhaust (-DPF), nitric oxide (NO), 43 ppm; nitrogen dioxide (NO2), 4 ppm; carbon monoxide (CO), 6 ppm; hydrocarbons, 11 ppm; particles, 3.2×10(5)/cm(3), 60-70nm mode, 269 μg/m(3); (2) treated exhaust (+DPF), NO, 20 ppm; NO2, 16 ppm; CO, 1 ppm; hydrocarbons, 3 ppm; and particles, 4.4×10(5)/cm(3), 7-8nm mode, 2 μg/m(3). Single exposures to -DPF exhaust resulted in increased neutrophils, total protein and the cytokines, growth-related oncogene/keratinocyte chemoattractant, macrophage inflammatory protein-1α, and monocyte chemoattractant protein-1 in lung lavage fluid, as well as increased gene expression of interleukin-6, prostaglandin-endoperoxide synthase 2, metallothionein 2A, tumor necrosis factor-α, inducible nitric oxide synthase, glutathione S-transferase A1, heme oxygenase-1, superoxide dismutase 2, endothelin-1 (ET-1), and endothelin-converting enzyme-1 in the lung, and ET- 1 in the heart. Ratio of bigET-1 to ET-1 peptide increased in plasma in conjunction with a decrease in endothelial nitric oxide synthase gene expression in the lungs after exposure to diesel exhaust, suggesting endothelial dysfunction. Rather than reducing toxicity, +DPF exhaust resulted in heightened injury and inflammation, consistent with the 4-fold increase in NO2 concentration. The ratio of bigET-1 to ET-1 was similarly elevated after -DPF and +DPF exhaust exposures. Endothelial dysfunction, thus, appeared related to particle number deposited, rather than particle mass or NO2 concentration. The potential benefits of particulate matter reduction using a catalyzed DPF may be confounded by increase in NO2 emission and release of reactive ultrafine particles.

Effect of Drive Cycle and Gasoline Particulate Filter on the Size and Morphology of Soot Particles Emitted from a Gasoline-Direct-Injection Vehicle

The size and morphology of particulate matter emitted from a light-duty gasoline-direct-injection (GDI) vehicle, over the FTP-75 and US06 transient drive cycles, have been characterized by transmission-electron-microscope (TEM) image analysis. To investigate the impact of gasoline particulate filters on particulate-matter emission, the results for the stock-GDI vehicle, that is, the vehicle in its original configuration, have been compared to the results for the same vehicle equipped with a catalyzed gasoline particulate filter (GPF). The stock-GDI vehicle emits graphitized fractal-like aggregates over all driving conditions. The mean projected area-equivalent diameter of these aggregates is in the 78.4-88.4 nm range and the mean diameter of primary particles varies between 24.6 and 26.6 nm. Post-GPF particles emitted over the US06 cycle appear to have an amorphous structure, and a large number of nucleation-mode particles, depicted as low-contrast ultrafine droplets, are observed in TEM images. This indicates the emission of a substantial amount of semivolatile material during the US06 cycle, most likely generated by the incomplete combustion of accumulated soot in the GPF during regeneration. The size of primary particles and soot aggregates does not vary significantly by implementing the GPF over the FTP-75 cycle; however, particles emitted by the GPF-equipped vehicle over the US06 cycle are about 20% larger than those emitted by the stock-GDI vehicle. This may be attributed to condensation of large amounts of organic material on soot aggregates. High-contrast spots, most likely solid nonvolatile cores, are observed within many of the nucleation-mode particles emitted over the US06 cycle by the GPF-equipped vehicle. These cores are either generated inside the engine or depict incipient soot particles which are partially carbonized in the exhaust line. The effect of drive cycle and the GPF on the fractal parameters of particles, such as fractal dimension and fractal prefactor, is insignificant.

Emissions Assessment of Alternative Aviation Fuel at Simulated Altitudes

To address the global fuel challenges of energy security, economic sustainability and climate change the stakeholders of aviation industry are actively pursuing the development and qualification of alternative ‘drop-in’ fuels. New standards will be required to regulate the use of these new fuels, which requires not only fuel specification and rig/engine and flight testing but also an emission life cycle impact assessment of these fuels. This paper reports on emission data measured at various simulated altitudes and engine speeds from a jet engine operated on conventional and alternative aviation fuels. The work was conducted as part of on-going efforts by departments within the Government of Canada to systematically assess regulated as well as non-regulated emissions from the use of alternative aviation fuels. The measurements were performed on an instrumented 1000 N-thrust turbojet engine using a baseline conventional Jet A-1 fuel and a semi-synthetic (50/50) blend with Camelina based Hydroprocessed Renewable Jet (JP8-HRJ8) fuel. Emission results reported here include carbon dioxide, carbon monoxide, nitrogen oxides and particulate matter measured at several simulated altitudes and power settings. In order to ensure that the assessments have a common baseline, relevant engine performance and operability data were also recorded.Copyright

Evaluation of an annular denuder system for carbonaceous aerosol sampling of diesel engine emissions

Sampling of particle-phase organic carbon (OC) from diesel engines is complicated by adsorption and evaporation of semivolatile organic carbon (SVOC), defined as positive and negative artifacts, respectively. In order to explore these artifacts, an integrated organic gas and particle sampler (IOGAPS) was applied, in which an XAD-coated multichannel annular denuder was placed upstream to remove the gas-phase SVOC and two downstream sorbent-impregnated filters (SIFs) were employed to capture the evaporated SVOC. Positive artifacts can be reduced by using a denuder, but particle loss also occurs. This paper investigates the IOGAPS with respect to particle loss, denuder efficiency, and particle-phase OC artifacts by comparing OC, elemental carbon (EC), SVOC, and selected organic species, as well as particle size distributions. Compared to the filter pack methods typically used, the IOGAPS approach results in estimation of both positive and negative artifacts, especially the negative artifact. The positive and negative artifacts were 190 µg/m3 and 67 µg/m3, representing 122% and 43% of the total particle OC measured by the IOGAPS, respectively. However, particle loss and denuder break-through were also found to exist. Monitoring particle mass loss by particle number or EC concentration yielded similar results ranging from 10% to 24% depending upon flow rate. Using the measurements of selected particle-phase organic species to infer particle loss resulted in larger estimates, on the order of 32%. The denuder collection efficiency for SVOCs at 74 L/min was found to be less than 100%, with an average of 84%. In addition to these uncertainties the IOGAPS method requires a considerable amount of extra effort to apply. These disadvantages must be weighed against the benefits of being able to estimate positive artifacts and correct, with some uncertainty, for the negative artifacts when selecting a method for sampling diesel emissions. Implications: Measurements of diesel emissions are necessary to understand their adverse impacts. Much of the emissions is organic carbon covering a range of volatilities, complicating determination of the particle fraction because of sampling artifacts. In this paper an approach to quantify artifacts is evaluated for a diesel engine. This showed that 63% of the particle organic carbon typically measured could be the positive artifact while the negative artifact is about one-third of this value. However, this approach adds time and expense and leads to other uncertainties, implying that effort is needed to develop methods to accurately measure diesel emissions. Supplemental Materials: Supplemental materials are available for this paper. Go to the publishers online edition of the Journal of the Air & Waste Management System.

Characterization of Emissions From the Use of Alternative Aviation Fuels

Alternative fuels for aviation are now a reality. These fuels not only reduce reliance on conventional petroleum-based fuels as the primary propulsion source, but also offer promise for environmental sustainability. While these alternative fuels meet the aviation fuels standards and their overall properties resemble those of the conventional fuel, they are expected to demonstrate different exhaust emissions characteristics because of the inherent variations in their chemical composition resulting from the variations involved in the processing of these fuels.This paper presents the results of back-to-back comparison of emissions characterization tests that were performed using three alternative aviation fuels in a GE CF-700-2D-2 engine core. The fuels used were an unblended synthetic kerosene fuel with aromatics (SKA), an unblended Fischer Tropsch synthetic paraffinic kerosene (SPK) and a semi-synthetic 50-50 blend of Jet A-1 and hydroprocessed SPK.Results indicate that while there is little dissimilarity in the gaseous emissions profiles from these alternative fuels, there is however a significant difference in the particulate matter emissions from these fuels. These differences are primarily attributed to the variations in the aromatic and hydrogen contents in the fuels with some contributions from the hydrogen-to-carbon ratio of the fuels.Copyright

Evaluation of the Impact of Alternative Fuel Use on the Emissions and Performance of a Service-Exposed T56 Engine

Alternative fuel sources are becoming an operational reality; these fuels have the potential to reduce emissions, improve combustion characteristics and to increase fuel supply security. A test with a T56 turboprop engine was performed to demonstrate that a CHEFA/JP8 (Camelina Hydroprocessed Ester and Fatty Acids and standard JP8) fuel blend would meet operational requirements. The primary test objective was to assess whether a fuel change had an immediate impact on the engine condition, performance, emissions or vibration characteristics. This paper presents test results comparing engine performance with JP8 and a 50/50 blend of JP8 and CHEFA. Comparison runs were conducted before and after a 20 hour ground durability test with the CHEFA fuel blend. A nearly time-expired, nacelle-dressed T56 on an outdoor test stand was tested. The engine was equipped with minimally-intrusive non-standard pressure, temperature and emissions monitoring equipment, and a field vibration assessment suite in addition to the standard flight instrumentation. This paper discusses the test plan, data acquisition methods, results and data repeatability. The performance and emissions results are compared to the changes predicted theoretically from the fuel properties. Observations from the borescope inspections before, during and after the 20 hour durability test are also presented. The lessons learned in this test could be applied to future fuel or process-change tests, and the results provide a performance baseline for engine health assessment.© 2012 ASME

Benchmarking data from the experience gained in engine performance and emissions testing on alternative fuels for aviation

Alternative fuel for aviation has been the centre of serious focus for the last decade, owing mostly to the challenges posed by the price of conventional petroleum fuel, energy security and environmental concerns. The downslide in the oil prices in the recent months and the fact that energy security is not considered a major threat in commercial aviation, these factors have worked negatively for the promotion of alternative fuels. However, the continuous commitment to environmental stewardship by Governments and the industry have kept the momentum going towards the transparent integration of renewable alternatives in the aviation market. On the regulatory side, much progress have been made in the same timeframe with five alternative fuels being certified as synthetic blending components for aviation turbine fuels for use in civil aircraft and engines. Another seven alternative fuels are in the various stages of certification protocol. This progress has been made possible because of the extensive performance testing, both at full engine conditions and at engine components level. This article presents the results of engine performance and air pollutant emissions measurements gathered from the alternative fuels qualification testing conducted at the National Research Council Canada over the last seven years. This benchmarking data was collected on various engine platforms at full engine operation at sea level and/or altitude conditions using a variety of aviation alternative fuels and their blends. In order to provide a reference comparison basis, the results collected using the alternative fuels are compared with baseline Jet-A1 or JP-8 conventional fuels. J. Glob. Power Propuls. Soc. | 2017, 1: 195–210 | https://doi.org/10.22261/S5WGLD 195 Introduction Owing to the remarkable and combined efforts from stakeholders across the complete fuel supply chain, alternative aviation fuels are now a reality. High oil prices and energy security, two of the main driving factors behind the initial quest for alternative fuels, are currently not of considerable concern in commercial aviation. In fact, the declining oil prices in the recent year or two have worked negatively for the promotion of alternative fuels. However, the commitment by Governments and the industry to reduce environmental impact have kept the momentum towards the development, certification and transparent integration of renewable alternatives in the aviation market. These fuels not only reduce reliance on conventional petroleum-based fuels as the primary propulsion source, but also offer promise for meeting the carbon-neutral growth target of aviation industry. As a result, fuels processed through five different pathways, Fischer Tropsch (FT), Hydroprocessed Esters and Fatty Acids (HEFA), Synthesized Iso-Paraffin (SIP), Synthesized Paraffinic Kerosene plus aromatics (SPK/A) and Alcohol to Jet (ATJ) have already been certified as blending components to the conventional jet fuel (ASTM International, 2017). Another seven alternative fuels are in the various stages of certification protocol, thus providing the aviation industry with a variety of fuel options. Similarly, from the bulk production perspective, tremendous progress has been made in the same timeframe where a number of demonstration and commercial facilities are either up and running or will be online shortly, with large conventional oil refineries teaming up with the developers of the various alternative fuel pathways. In the last decade, Canada has been involved in the area of aviation alternative fuels with activities ranging from the development of feedstock (e.g., brassica carinata) (Agriculture and Agri-Food Canada, 2015), to conversion into fuels and in the industrial qualification and demonstration of these fuels both on ground (subject of this article) and in flight (Park, 2012). The results on engine performance and air pollutant emissions, gathered from the alternative fuels qualification testing conducted over the last seven years are presented here. The work was jointly conducted by National Research Council Canada and Environment and Climate Change Canada and funded through various Government of Canada departments. Test platforms and fuels As shown in Table 1, the benchmarking data was collected on various engine platforms ranging from turbofan (F-404-400 and CF-700) to turbojet (TRS-18-046-1) to turboprop (T-56-A15) and using a variety of aviation alternative fuels and their blends at both sea level and altitude conditions. In order to provide a reference for comparison, the results collected using the alternative fuels were compared with baseline petroleum-based Jet-A1 or JP-8 conventional fuels. Some selected engine specifications as well as some key properties of the fuels, used in the various test campaigns, are given in Appendix A (Table A1 and Table A2). The first effort was undertaken in 2009 to qualify General Electric F-404-400 engine on a semisynthetic jet fuel, which was a 50-50 blend of conventional Jet A-1 and FT fuels (Hadzic et al., 2010). The Synthesized Paraffinic Kerosene (SPK) FT fuel used was in turn a blend of coal-to-liquid (2/3 by volume) and gas-to-liquid (1/3 by volume) fuels refined from SASOL and Shell respectively. Engine performance, operability and emissions as well as engine durability, through accelerated mission simulation tests (GE, 1976), were conducted under this test campaign. This was followed by a novel effort in 2010 involving the evaluation of three different alternative fuels under test-cell simulated altitude conditions (Chishty et al., 2011). The test fuels were: a fullysynthetic FT SPK; a semi-synthetic 50-50 blend of FT-SPK and JP-8; and a semi-synthetic 50-50 blend of Camelina based HEFA SPK and JP-8. The test vehicle was a specially instrumented 1000 Nthrust TRS18-046-1 turbojet engine from Microturbo. The experimental investigations included steady state and transient engine operations as well as emissions measurements at nominal test-cell altitudes (pressure and temperature) of 1,500, 3,000, 6,000, 9,000 and 11,500 m. Chishty et al. | Engine Performance/Emissions from Alternative Aviation Fuels https://journal.gpps.global/a/S5WGLD/ J. Glob. Power Propuls. Soc. | 2017, 1: 195–210 | https://doi.org/10.22261/S5WGLD 196 The next activity was another engine qualification test campaign in 2011, this time using semisynthetic 50-50 blend of Camelina based HEFA SPK and JP-8 fuels on a Rolls-Royce/Alison T-56A15 engine (Chalmers et al., 2012). Engine performance, operability, high-temperature 50-hr durability (Allison Gas Turbine Division, 1985) and emissions aspects were investigated. A special objective of the work was to test the use of alternative fuel on a nearly life-expired engine with more than 6,000 hours of operation after last overhaul. As such, post-durability teardown inspection was also conducted and the hot-section components were subjected to material testing to assess the degradation of these components. The next series of tests were conducted in 2012 using a General Electric CF-700 engine core using a 100% unblended synthetic kerosene fuel with aromatics (SKA) manufactured through the Catalytic Hydrothermolysis (CH) process (Davison et al., 2015). The feedstock for this fuel was a Canadian industrial crop called brassica carinata. Two additional fuels namely, a fully-synthetic 100% FT SPK and a semi-synthetic 50-50 blend of Camelina based HEFA SPK and JP-8 were also evaluated, backto-back. As with the previous three projects, the whole suite of engine performance and emissions characterization was accomplished. This particular engine testing served to gain experience on the novel unblended CH renewable fuel with aromatics, prior to the world-first 100% biofuel flight conducted by National Research Council Canada (Park, 2012). Recently in 2015, the TRS18-046-1 engine platform was used again to test another novel emerging fuel called Hydrodeoxygenated Synthesized Aromatic Kerosene (HDO SAK) at test-cell simulated altitudes (Canteenwalla et al., 2016). HDO SAK is composed of approximately 95% mono-aromatic compounds. The special purpose of this testing was to investigate engine performance and emissions when using blends of SAK fuel at various levels of aromatic content in the fuel and to compare the results with conventional jet fuel. This testing also provided valuable information regarding differences between synthetically produced aromatics and conventional petroleum based aromatics. Test and measurement methodology In all the test campaigns reported here, the following elements and measurements were compiled: a) Operability runs to demonstrate engine functionality during cold and hot starts and transient operations like rapid acceleration (slam) and rapid deceleration (chop). b) Performance runs to document engine performance under steady conditions at idle, cruise and take-off conditions. Table 1. Overview of engine platforms and fuels tested during the test campaigns reported here. Engines Fuels & Blends F-404-400 T-56-A15 CF-700 TRS-18-046-1 100% FT SPK Sea level Altitude 50% FT SPK in JP-8 Sea level Altitude 50% HEFA SPK in JP-8 Sea level Sea level Altitude 100% CH SKA Sea level 17% HDO SAK in HEFA SPK Altitude 9% HDO SAK in HEFA SPK Altitude Chishty et al. | Engine Performance/Emissions from Alternative Aviation Fuels https://journal.gpps.global/a/S5WGLD/ J. Glob. Power Propuls. Soc. | 2017, 1: 195–210 | https://doi.org/10.22261/S5WGLD 197 c) Emissions measurements, gaseous and particulate matter, conducted at steady state engine operation. d) Durability runs (accelerated or limited endurance) for the cases of F-404-400 and T-56-A15 engines. The results of durability tests are not part of this article. e) Post-test engine teardown inspection for the cases of T-56-A15 and TRS-18-046-1. The results of teardown inspections are not part of this article. All static sea level tests, except for the T-56-A15 engine tests, and al

The effects of biodiesels on semivolatile and nonvolatile particulate matter emissions from a light-duty diesel engine

Semivolatile organic compounds (SVOCs) represent a dominant category of secondary organic aerosol precursors that are increasingly included in air quality models. In the present study, an experimental system was developed and applied to a light-duty diesel engine to determine the emission factors of particulate SVOCs (pSVOCs) and nonvolatile particulate matter (PM) components at dilution ratios representative of ambient conditions. The engine was tested under three steady-state operation modes, using ultra-low-sulfur diesel (ULSD), three types of pure biodiesels and their blends with ULSD. For ULSD, the contribution of pSVOCs to total particulate organic matter (POM) mass in the engine exhaust ranged between 21 and 85%. Evaporation of pSVOCs from the diesel particles during dilution led to decreases in the hydrogen to carbon ratio of POM and the PM number emission factor of the particles. Substituting biodiesels for ULSD could increase pSVOCs emissions but brought on large reductions in black carbon (BC) emissions. Among the biodiesels tested, tallow/used cooking oil (UCO) biodiesel showed advantages over soybean and canola biodiesels in terms of both pSVOCs and nonvolatile PM emissions. It is noteworthy that PM properties, such as particle size and BC mass fraction, differed substantially between emissions from conventional diesel and biodiesels.