Search Results

Abstract An investigation into the pre-ashing of new gasoline particulate filters (GPFs) has demonstrated that the filtration efficiency of such filters can be improved by up to 30% (absolute efficiency improvement) when preconditioned using ash derived from a fuel-borne catalyst (FBC) additive. The additive is typically used in diesel applications to enable diesel particulate filter (DPF) regeneration and can be added directly into the fuel tank of the vehicle. This novel result was compared with ash derived from lube oil componentry, which has previously been shown to improve filtration efficiency in GPFs. The lube oil-derived ash utilized in this work improved the filtration efficiency of the GPF by −30%, comparable to the ash derived from the FBC additive.

Abstract The use of appropriate loads and regulations is of great importance in weld fatigue assessment of rail on-track maintenance equipment and similar vehicles for optimized design. The regulations and available loads, however, are often generalized for several categories, which proves to be overly conservative for some specific categories of machines. EN (European Norm) and AAR (Association of American Railroads) regulations play a pivotal role in determining the applicable loads and acceptance criteria within this study. The availability of track-induced fatigue load data for the cumulative damage approach in track maintenance machines is often limited. Consequently, the FEA-based validation of rail track maintenance equipment often resorts to the infinite life approach rather than cumulative damage approach for track-induced travel loads, resulting in overly conservative designs.

Abstract The water droplet erosion (WDE) on high-speed rotating wheels appears in several engineering fields such as wind turbines, stationary steam turbines, fuel cell turbines, and turbochargers. The main reasons for this phenomenon are the high relative velocity difference between the colliding particles and the rotor, as well as the presence of inadequate material structure and surface parameters. One of the latest challenges in this area is the compressor wheels used in turbochargers, which has a speed up to 300,000 rpm and have typically been made of aluminum alloy for decades, to achieve the lowest possible rotor inertia. However, while in the past this component was only encountered with filtered air, nowadays, due to developments in compliance with tightening emission standards, various fluids also collide with the spinning blades, which can cause mechanical damage.

Abstract Dynamic stresses exist in parts of a catalyst muffler caused by the vibration of a moving vehicle, and it is important to clarify and predict the vibration response properties for preventing fatigue failures. Assuming a vibration isolating installation in the vehicle frame, the vibration transmissibility and local dynamic stress of the catalyst muffler were examined through a vibration machine. Based on the measured data and by systematically taking vibration theories into consideration, a new prediction method of the vibration modes and parameters was proposed that takes account of vibration isolating and damping. A lumped vibration model with the six-element and one mass point was set up, and the vibration response parameters were analyzed accurately from equations of motion. In the vibration test, resonance peaks from the hanging bracket, rubber bush, and muffler parts were confirmed in three excitation drives, and local stress peaks were coordinate with them as well.

Abstract The riding-comfort of high-speed trains affects the travel experience of passengers, and the lightweight design technology of the carbody increases the flexible vibration and reduces passenger comfort. To this end, a vertical dynamics model of railway vehicles is established to demonstrate the potential of using passive inerter-based suspensions to reduce the flexible vibration of the carbody and improve riding-comfort. According to the characteristics of the inerter component, an appropriate inerter-based suspension is applied to the railway vehicle to reduce low-frequency resonance. The sum of the comfort indexes of the three reference points of the carbody is optimized as the objective function to improve the passenger comfort of the whole vehicle. The results reveal that the inerter-based suspension applied to the primary or secondary suspension has different effects on vehicle vibration.

Abstract With the reduction in PM emission standards for light duty vehicles to 3 mg/mi for current Federal and California standards and subsequently to 1 mg/mi in 2025 for California, the required PM measurements are approaching the detection limits of the gravimetric method. A “filter survey” was conducted with 11 laboratories, representing industry, agencies, research institutes, and academic institutions to analyze the accuracy of the current gravimetric filter measurement method under controlled conditions. The reference filter variability, measured within a given day over periods as short as an hour, ranged from 0.61 μg to 2 μg to 5.0 μg for the 5th, 50th, 95th percentiles (n > 40,000 weights, 317 reference objects), with a laboratory average of 2.5 μg.

Abstract Sustainable practices are taking precedence across many industries, as evident from their shift towards the use of environmentally responsible materials, such as natural fiber-reinforced acrylated epoxidized soybean oil (NF-AESO). However, due to the lower reactivity of AESO, the curing reaction usually requires higher temperatures and longer curing time (e.g., 150°C for 6-12 h), thus making the entire process unsustainable. In this study, we demonstrate the potential power of photons towards manufacturing NF-AESO composites in a sustainable manner at room temperature (RT) within 10 min. Two photoinitiators, i.e., the 2,2-dimethoxy phenylacetophenone (DMPA) and 1-hydroxycyclohexyl phenyl ketone (HCPK), were evaluated and compared with the thermal initiator, i.e., tert-butyl perbenzoate (TBPB). Based on the mechanical performance of the AESOs, the photoinitiation system for NF-AESO was optimized.

Abstract To reduce fuel consumption and carbon dioxide (CO2) emissions from mobile air conditioning (A/C) systems, “U.S. Light-Duty Vehicle Greenhouse Gas Emissions and Corporate Average Fuel Economy Standards” identified solar/thermal technologies such as solar control glazings, solar reflective paint, and active and passive cabin ventilation in an off-cycle credit menu. National Renewable Energy Laboratory (NREL) researchers developed a sophisticated analysis process to calculate U.S. light-duty A/C fuel use that was used to assess the impact of these technologies, leveraging thermal and vehicle simulation analysis tools developed under previous U.S. Department of Energy projects. Representative U.S. light-duty driving behaviors and weighting factors including time-of-day of travel, trip duration, and time between trips were characterized and integrated into the analysis.

Abstract In urban roads the engine speed and the load vary suddenly and frequently, resulting in increased exhaust emissions. In such operations, the effect of air injection technique to access the transient response of the engine is of great interest. The effectiveness of air injection technique in improving the transient response under speed transient is investigated in detail [1]; however, it is not evaluated for the load transients. Load step demand of the engine is another important event that limits the transient response of the turbocharger. In the present study, response of a heavy-duty turbocharged diesel engine is investigated for different load conditions. Three cases of load transients are considered: constant load, load magnitude variation, and load scheduling. Air injection technique is simulated and after optimization of injection pressure based on orifice diameter, its effect on the transient response is presented.

Abstract Low-Pressure cooled Exhaust Gas Recirculation (LP-cEGR) is proven to be an effective technology for fuel efficiency improvement in turbocharged spark-ignition (SI) engines. Aiming to fully exploit the EGR benefits, new challenges are introduced that require more complex and robust control systems and strategies. One of the most important restrictions of LP-cEGR is the transient response, since long air-EGR flow paths introduce significant transport delays between the EGR valve and the cylinders. High dilution generally increases efficiency, but can lead to cycle-by-cycle combustion variation. Especially in SI engines, higher-than-requested EGR dilution may lead to combustion instabilities and misfires. Considering the long EGR evacuation period, one of the most challenging transient events is throttle tip-out, where the engine operation shifts from a high-load point with high dilution tolerance to a low-load point where EGR tolerance is significantly reduced.

Abstract Current End-of-Life Vehicle (ELV) recycling processes are mainly based on mechanical separation techniques. These methods are designed to recycle those metals with the highest contribution in the vehicle weight such as steel, aluminum, and copper. However, a conventional vehicle uses around 50 different types of metals, some of them considered critical by the European Commission. The lack of specific recycling processes makes that these metals become downcycled in steel or aluminum or, in the worst case, end in landfills. With the aim to define several ecodesign recommendations from a raw material point of view, it is proposed to apply a thermodynamic methodology based on exergy analysis. This methodology uses an indicator called thermodynamic rarity to assess metal sustainability. It takes into account the quality of mineral commodities used in a vehicle as a function of their relative abundance in Nature and the energy intensity required to extract and process them.

Abstract The wide application of Gasoline Direct Injection (GDI) engines and the increasingly stringent Particulate Matter (PM) and Particulate Number (PN) regulations make Gasoline Particulate Filters (GPFs) with high filtration efficiency and low pressure drop highly desirable. However, due to the specifics of GDI operation and GDI PM, the design of these filters is even more challenging as compared to their diesel counterparts. Computational Fluid Dynamics (CFD) studies have been shown to be an effective way to investigate filter performance. In particular, our previous two-dimensional (2D) CFD study explicated the pore size and pore-size distribution effects on GPF filtration efficiency and pressure drop. The “throat unit collector” model developed in this study furthers this work in order to characterize the GPF wall microstructure more precisely.

Abstract Accurate exhaust gas temperature (EGT) measurements are vital in the design and development process of internal combustion engines (ICEs). The unsteady ICE exhaust flow and thermal inertia of commonly used sheathed thermocouples and resistance thermometers require high bandwidth EGT pulse measurements for accurate cycle-resolved and mean EGTs. The EGT pulse measurement challenge is typically addressed using exposed thin-wire resistance thermometers or thermocouples. The sensor robustness to response tradeoff limits ICE tests to short durations over a few exhaust conditions. Larger diameter multiwire thermocouples using response compensation potentially overcomes the tradeoff. However, the literature commonly adopts weaker slack wire designs despite indications of coated weld taut wires being robust.

Abstract Uncertainty of fuel reserves, environmental crisis, and health concerns arise from transport demands and reliance on fossil fuels. Downsized gasoline turbocharged direct injection (GTDI) engines have been developed and applied to most modern gasoline vehicles, delivering superior efficiency in high-load operation, reduced friction, and weight. But fuel enrichment and late combustion phasing to mitigate knocking combustion have hindered the efficiency benefits at higher loads with high boost. Furthermore, the wide valve-overlap with a three-cylinder setup for the maximum scavenging efficiency produces bursts of short-circuit (SC) air to cause underestimation of the equivalence ratio by the oxygen sensor, resulting in higher tailpipe nitrogen oxides (NOx) emissions with three-way catalyst (TWC) exhaust aftertreatment. Reducing the valve overlap to limit short-circuiting and enrichment will recover the combustion efficiency and the engine ER, but at the cost of high knock onset.

Abstract To assess the effect of the presence of carbon dioxide (CO2) in natural gases on the knock resistance of fuel, the knock behavior of a lean-burn, high-speed medium Brake Mean Effective Pressure (BMEP) Combined Heat and Power (CHP) engine fueled with CH4 + 8 mole% C3H8 mixtures. The engine experiments are supplemented with ignition measurements and simulations of ignition and cylinder processes for various fuel compositions. The engine results show that increasing the fraction of CO2 results in an increase in knock resistance. The analysis of simulations of cylinder processes shows that for binary mixtures (CH4/CO2) and ternary mixtures (CH4/C3H8/CO2) the increase in knock resistance with increasing CO2 fraction is caused by the reduction in peak pressure/temperature, which consequently increases the autoignition delay time of the mixture.

Abstract The article describes the results achieved in developing a new diesel combustion system for passenger car application that, while capable of high power density, delivers excellent fuel economy through a combination of mechanical and thermodynamic efficiencies improvement. The project stemmed from the idea that, by leveraging the high fuel injection pressure of last generation common rail systems, it is possible to reduce the engine peak firing pressure (pfp) with great benefits on reciprocating and rotating components’ light-weighting and friction for high-speed light-duty engines, while keeping the power density at competitive levels. To this aim, an advanced injection system concept capable of injection pressure greater than 2500 bar was coupled to a prototype engine featuring newly developed combustion system. Then, the matching among these features has been thoroughly experimentally examined.

Abstract To protect ship equipment of river and sea transport, it is suggested to use polymeric protective coatings based on epoxy diane oligomer ED-20, polyethylene polyamine (PEPA) curing agent and filler, which is a departure from industrial production. Thus the purpose of the work is analysis of major dependency of the properties on the content of fillers that allowed to revealed the critical filler content (furnace black) in composites to form a protective coating with the required set of characteristics. The infrared (IR) spectral analysis was used to investigate the presence of bonds on the surface of particles of the PM-75 furnace black, which allows us to assess the degree of cross-linking of the polymer. The influence of the content of dispersed furnace black on the physicomechanical and thermophysical properties and the structure of the protective coating is investigated.

Abstract In the development of hydrocarbon (HC) traps for E85 fuel vehicle emission control, the addition of palladium (Pd) to BEA zeolite was studied for trapping and decreasing cold-start ethanol emissions. BEA zeolite after a laboratory aging at 750°C for 25 hours released nearly all of the trapped ethanol as unconverted ethanol at low temperature, and some ethene was released at a higher temperature by a dehydration reaction. The addition of Pd to BEA zeolite showed a decrease in the release of unconverted ethanol emissions even after the lab aging. The release of methane (CH4), acetaldehyde (CH3CHO), carbon monoxide (CO), and CO2 from Pd-BEA zeolite during desorption (temperature programmed desorption (TPD)) demonstrated that multiple ethanol reaction mechanisms were involved including dehydrogenation and decomposition reactions.

Abstract Different aftertreatment systems consisting of a combination of selective catalytic reduction (SCR) and SCR catalyst on a diesel particulate filter (DPF) (SCR-F) are being developed to meet future oxides of nitrogen (NOx) emissions standards being set by the Environmental Protection Agency (EPA) and the California Air Resources Board (CARB). One such system consisting of a SCRF® with a downstream SCR was used in this research to determine the system NOx reduction performance using experimental data from a 2013 Cummins 6.7L ISB diesel engine and model data. The contribution of the three SCR reactions on NOx reduction performance in the SCR-F and the SCR was determined based on the modeling work. The performance of a SCR was simulated with a one-dimensional (1D) SCR model. A NO2/NOx ratio of 0.5 was found to be optimum for maximizing the NOx reduction and minimizing NH3 slip for the SCR for a given value of ammonia-to-NOx ratio (ANR).

Abstract The present study evaluates the effect of engine speed, exhaust gas recirculation (EGR), and compression ratio on conventional diesel combustion (CDC) and two isobaric combustion cases, by utilizing multiple injection strategies. The experiments were conducted in a Volvo D13C500 single-cylinder, heavy-duty engine, fuelled with standard European Union (EU) diesel fuel. The engine was operated at three different speeds of 1200, 1500, and 1800 revolutions per minute (rpm). For each engine speed and combustion cases, the EGR rate was varied from 0% to 40%. The low-pressure isobaric combustion (IsoL) and high-pressure isobaric combustion (IsoH) were maintained at peak cylinder pressure (PCP) of 50 and 68 bar, respectively, which was representative of the peak motoring pressure (PMP) and PCP of CDC. This was possible by adjusting the intake air pressure to 1.7 and 2.3 bar—absolute for IsoL and IsoH, respectively, at 1200 rpm.