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While gasoline surrogate development has progressed in the areas of more complex surrogate mixtures and in kinetic modeling tools and mechanism development, it is generally recognized that further development is still needed. This paper represents a small step in supporting this development by providing comparisons between experimental engine data and surrogate-based kinetic models. In our case, the HCCI engine data comes from a port-injected, single-cylinder research engine with intake-air heating for combustion phasing control. Timing sweeps were run at constant fuel rate for three market gasolines and five surrogate mixtures. Modeling was done using the CHEMKIN software with a gasoline mechanism set containing 1440 species and 6572 reactions. Five pure compounds were selected for the surrogate blends and include iso-octane, n-heptane, toluene, methylcyclohexane, and 1-hexene.

Thermal conductivity detection has long been used in gas chromatography to detect hydrogen and other diatomic gases in a gas sample. Thermal conductivity instruments that are not coupled to gas chromatographs are useful for detecting hydrogen in binary gas mixtures, but suffer from significant cross-interference from other gas species that are separated when the detector is used with a gas chromatograph. This study reports a method for using a commercially-available thermal conductivity instrument to detect and quantify hydrogen in a diesel exhaust stream. The instrument time response of approximately 40 seconds is sufficient for steady-state applications. Cross-interference from relevant gas species are quantified and discussed. Measurement uncertainty associated with the corrections for the various species is estimated and practical implications for use of the instrument and method are discussed.

A modified Mercedes 1.7-liter, direct-injection diesel engine was operated in both normal and high-efficiency clean combustion (HECC) combustion modes. Four steady-state engine operating points that were previously identified by the Ad-hoc fuels working group were used as test points to allow estimation of the hot-start FTP-75 emissions levels in both normal and HECC combustion modes. The results indicate that operation in HECC modes generally produce reductions in NOX and PM emissions at the expense of CO, NMHC, and H2CO emissions. The FTP emissions estimates indicate that aftertreatment requirements for NOX are reduced, while those for PM may not be impacted. Cycle-average aftertreatment requirements for CO, NMHC, and H2CO may be challenging, especially at the lowest temperature conditions.

As interest has grown in diesel emissions and diesel engine aftertreatment, so has the importance of analyzing all components of the exhaust. One of the more costly and difficult measurements to make is the collection and analysis of semivolatile organic compounds (SOCs) in the exhaust. These compounds include alkane and alkenes from C12-C24, and the 2-5 ring polycyclic aromatic hydrocarbons (PAH). These compounds can be present in both the particulate (i.e. on the filter) and gaseous phase, and cannot be collected with bag samples. Typically, a sorbent is used downstream of the particulate collection filters to collect these compounds. Sorbent phases include polyurethane foam (PUF), Tenax™, XAD-type resins, and activated carbon. The SOCs are removed from the sorbent either by solvent extraction (PUF and XAD) or thermal desorption (Tenax™ and activated carbon). Each of these methods have advantages and disadvantages.

The variability in gasoline energy content, though most frequently not a consumer concern, is an issue of concern for vehicle manufacturers in demonstrating compliance with regulatory requirements. Advancements in both vehicle technology, test methodology, and fuel formulations have increased the level of visibility and concern with regard to the energy content of fuels used for regulatory testing. The R factor was introduced into fuel economy calculations for vehicle certification in the late 1980s as a means of addressing batch-to-batch variations in the heating value of certification fuels and the resulting variations in fuel economy results. Although previous studies have investigated values of the R factor for modern vehicles through experimentation, subsequent engine studies have made clear that it is difficult to distinguish between the confounding factors that influence engine efficiency when R is being studied experimentally.

A high-resolution corrosion probe was placed within the airhorn section of the exhaust gas recirculation (EGR) loop of a heavy-duty diesel engine. The corrosion rate of the mild-steel probe elements was evaluated as a function of fuel sulfur level, EGR fraction, dewpoint margin, and humidity. No significant corrosion was observed while running the engine using a No. 2 grade, < 15ppm sulfur diesel fuel; however, high corrosion rates were observed with No. 2 diesel fuel (∼350 ppm sulfur) while condensing water in the EGR loop. The rate of corrosion on the mild steel elements increased with increasing levels of sulfate in the condensate. However, the engine conditions influencing the sulfate level were not clearly identified in this study.

The low temperature conditions that occur during high efficiency clean combustion (HECC) often lead to the formation of partially oxidized HC species such as aldehydes, ketones and carboxylic acids. Using the diesel fuels specified by the Fuels for Advanced Combustion Engines (FACE) working group, carbonyl species were collected from the exhaust of a light duty diesel engine operating under HECC conditions. High pressure liquid chromatography - mass spectrometry (LC-MS) was used to speciate carbonyls as large as C 9 . A relationship between carbonyl species formed in the exhaust and fuel composition and properties was determined. Data were collected at the optimum fuel efficiency point for a typical road load condition. Results of the carbonyl analysis showed changes in formaldehyde and acetaldehyde formation, formation of higher molecular weight carbonyls and the formation of aromatic carbonyls.

The effects of cetane number (CN) on homogeneous charge compression ignition (HCCI) performance and emissions were investigated in a single cylinder engine using intake air temperature for control. Blends of the diesel secondary reference fuels for cetane rating were used to obtain a CN range from 19 to 76. Sweeps of intake air temperature at a constant fueling were performed. Low CN fuels needed to be operated at higher intake temperatures than high CN fuels to achieve ignition. As the intake air temperature was reduced for a given fuel, the combustion phasing was retarded, and each fuel passed through a phasing point of maximum indicated mean effective pressure (IMEP). Early combustion phasing was required for the high CN fuels to prevent misfire, whereas the maximum IMEP for the lowest CN fuel occurred at a phasing 10 crank angle degrees (CAD) later.

Exhaust gas recirculation (EGR) cooler fouling has become a significant issue for compliance with nitrogen oxides (NOx) emissions standards. In order to better understand fouling mechanisms, eleven field-aged EGR coolers provided by seven different engine manufacturers were characterized using a suite of techniques. Microstructures were characterized using scanning electron microscopy (SEM) and optical microscopy following mounting the samples in epoxy and polishing. Optical microscopy was able to discern the location of hydrocarbons in the polished cross-sections. Chemical compositions were measured using thermal gravimetric analysis (TGA), differential thermal analysis (DTA), gas chromatography-mass spectrometry (GC-MS), x-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS) and x-ray diffraction (XRD). Mass per unit area along the length of the coolers was also measured.

The CRC Fuels for Advanced Combustion Engines (FACE) Working Group has provided a matrix of experimental diesel fuels for use in studies on the effects of three parameters, Cetane number (CN), aromatics content, and 90 vol% distillation temperature (T90), on combustion and emissions characteristics of advanced combustion strategies. Various types of fuel analyses and engine experiments were performed in well-known research institutes. This paper reviews a collection of research findings obtained with these nine fuels. An extensive collection of analyses were performed by members of the FACE working group on the FACE diesel fuels as a means of aiding in understanding the linkage between fuel properties and combustion and emissions performance. These analyses included non-traditional chemical techniques as well as established ASTM tests. In a few cases, both ASTM tests and advanced analyses agreed that some design variables differed from their target values when the fuels were produced.

To address the growing need for accurate predictions of combustion phasing and emissions for development of advanced engines, a more accurate definition of model fuels and their associated chemical-kinetics mechanisms are necessary. Wide variations in street fuels require a model-fuel blending methodology to allow simulation of fuel-specific characteristics, such as ignition timing, emissions, and fuel vaporization. We present a surrogate-blending technique that serves as a practical modeling tool for determination of surrogate blends specifically tailored to different real-fuel characteristics, with particular focus on model fuels for gasoline engine simulation. We start from a palette of potential model-fuel components that are based on the characteristic chemical classes present in real fuels. From this palette, components are combined into a surrogate-fuel blend to represent a real fuel with specific fuel properties.

The effect of biodiesel content on homogeneous charge compression ignition (HCCI) engine performance has been investigated both experimentally and by computer simulation. Combustion experiments were performed in a single cylinder HCCI engine using blends of soy biodiesel in ultra low sulfur diesel, with concentrations ranging from 0 to 50 vol% and equivalence ratios (Φ) from 0.38 to 0.48. Data from the engine tests included combustion analysis and exhaust composition analysis with standard gaseous emissions equipment. The engine utilized a custom port fuel injection strategy to provide highly premixed charges of fuel and air, making it possible to compare the results with single zone chemical kinetics simulations that were performed using CHEMKIN III, with a reaction set including 670 species and over 3000 reactions.

The present study was motivated by a need to expand information for consumers offered through the FuelEconomy.Gov website. To that end, a power-based modeling approach has been used to examine the effect of steady-speed driving on estimated range for model year 2020 – 2023 battery electric vehicles (BEVs). This approach allowed rapid study of a broader range of BEV models than could be accomplished through vehicle tests. Publicly accessible certification test results and other data were used to perform a regression between cycle-average tractive power requirements and the resulting electrical power. This regression enabled estimation of electric power and energy use over a range of steady highway speeds. These analyses in turn allowed projection of vehicle range at differing speeds. The projections agree within 6% with available 65 MPH manufacturer test data.

The poisoning of diesel oxidation catalysts (DOCs) by the engine oil additive zinc dialkyldithiophosphate (ZDDP) is investigated in the present study. A 517cc single-cylinder diesel engine is used to accelerate the phosphorus poisoning of DOCs by artificially increasing the ZDDP consumption to approximately 700 times normal operation by three different methods. These include lube-oil doped fuel, intake manifold, and exhaust manifold injection with lube-oil containing an elevated level of ZDDP. The deactivation of DOCs under these conditions is characterized by a variety of physical and chemical techniques. Surface composition and structure of the poisoned catalysts analyzed with SEM-EDS show differences depending on the method of ZDDP introduction. Exhaust manifold injection produces a zinc phosphate glaze which masks the surface to species diffusion. Fuel and intake manifold injection methods produce chemically absorbed phosphorus on the catalyst washcoat surface.

During the 1980s, the U.S. Environmental Protection Agency (EPA) incorporated the R factor into fuel economy calculations in order to address concerns about the impacts of test fuel property variations on corporate average fuel economy (CAFE) compliance, which is determined using the Federal Test Procedure (FTP) and Highway Fuel Economy Test (HFET) cycles. The R factor is defined as the ratio of the percent change in fuel economy to the percent change in volumetric heating value for tests conducted using two differing fuels. At the time the R-factor was devised, tests using representative vehicles initially indicated that an appropriate value for the R factor was 0.6. Reassessing the R factor has recently come under renewed interest after EPA's March 2013 proposal to adjust the properties of certification gasoline to contain significant amounts of ethanol.

The accelerated ash loading of diesel particulate filters (DPFs) with diesel oxidation catalysts (DOCs) mounted upstream by lube-oil derived products was investigated using a single cylinder diesel engine and fuel blended with 5% lube oil. An ash loading protocol is developed which combines soot loading, active soot regeneration, and periodic shutdowns for filter weighing. Active regeneration is accomplished by exhaust injection of diesel fuel, initiated by a backpressure criteria and providing DPF temperatures up to 700°C. In developing this protocol, five DPFs of various combinations of substrates (cordierite, silicon carbide, and mullite) and washcoats (none, low PGM, and high PGM) are used and evaluated. The initial backpressure and rate of backpressure increase with ash varied with each of the DPFs and ash was observed to have an effect on the active soot light-off temperature for the catalyzed DPFs.

The buildup of deposits in EGR coolers causes significant degradation in heat transfer performance, often on the order of 20-30%. Deposits also increase pressure drop across coolers and thus may degrade engine efficiency under some operating conditions. It is unlikely that EGR cooler deposits can be prevented from forming when soot and HC are present. The presence of cooled surfaces will cause thermophoretic soot deposition and condensation of HC and acids. While this can be affected by engine calibration, it probably cannot be eliminated as long as cooled EGR is required for emission control. It is generally felt that “dry fluffy” soot is less likely to cause major fouling than “heavy wet” soot. An oxidation catalyst in the EGR line can remove HC and has been shown to reduce fouling in some applications. The combination of an oxidation catalyst and a wall-flow filter largely eliminates fouling. Various EGR cooler designs affect details of deposit formation.

Exhaust gas recirculation (EGR) cooler fouling has become a significant issue for compliance with NOx emissions standards. This paper reports results of a study of fundamental aspects of EGR cooler fouling. An apparatus and procedure were developed to allow surrogate EGR cooler tubes to be exposed to diesel engine exhaust under controlled conditions. The resulting fouled tubes were removed and analyzed. Volatile and non-volatile deposit mass was measured for each tube. Thermal diffusivity of the deposited soot cake was measured by milling a window into the tube and using the Xenon flash lamp method. The heat capacity of the deposit was measured at temperatures up to 430°C and was slightly higher than graphite, presumably due to the presence of hydrocarbons. These measurements were combined to allow calculation of the deposit thermal conductivity, which was determined to be 0.041 W/mK, only ∼1.5 times that of air and much lower than the 304 stainless steel tube (14.7 W/mK).

Exhaust gas recirculation (EGR) coolers experience degradation of performance as a result of the buildup of material in the gas-side flow paths of the cooler. This material forms a deposit layer that is less thermally conductive than the stainless steel of the tube enclosing the gas, resulting in lower heat exchanger effectiveness. Biodiesel fuel has a fuel chemistry that is much more susceptible to polymerization than that of typical diesel fuels and may exacerbate deposit formation in EGR coolers. A study was undertaken to examine the fundamentals of EGR cooler deposit formation by using surrogate tubes to represent the EGR cooler. These tubes were exposed to engine exhaust in a controlled manner to assess their effectiveness, deposit mass, and deposit hydrocarbon content. The tubes were exposed to exhaust for varying lengths of time and for varying coolant temperatures. The results show that measurable differences in the response variables occur within a few hours.

In this investigation, oil shale crude obtained from the Green River Formation in Colorado using Paraho Direct retorting was mildly hydrotreated and distilled to produce 7 narrow boiling point fuels of equal volumes. The resulting derived cetane numbers ranged between 38.3 and 43.9. Fuel chemistry and bulk properties strongly correlated with boiling point. The fuels were run in a simple HCCI engine to evaluate combustion performance. Each cut exhibited elevated NOx emissions, from 150 to 300ppm higher than conventional ULSD under similar conditions. Engine performance and operating range were additionally dictated by distillation temperatures which are a useful predictor variable for this fuel set. In general, cuts with low boiling point achieved optimal HCCI combustion phasing while higher boiling point cuts suffered a 25% fuel economy decrease, compared to conventional diesel under similar HCCI conditions, and incurred heavy engine deposits.