Search Results

Abstract This study demonstrates the defossilized operation of a heavy-duty port-fuel-injected dual-fuel engine and highlights its potential benefits with minimal retrofitting effort. The investigation focuses on the optical characterization of the in-cylinder processes, ranging from mixture formation, ignition, and combustion, on a fully optically accessible single-cylinder research engine. The article revisits selected operating conditions in a thermodynamic configuration combined with Fourier transform infrared spectroscopy. One approach is to quickly diminish fossil fuel use by retrofitting present engines with decarbonized or defossilized alternatives. As both fuels are oxygenated, a considerable change in the overall ignition limits, air–fuel equivalence ratio, burning rate, and resistance against undesired pre-ignition or knocking is expected, with dire need of characterization.

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 The two-branch exhaust of an asymmetric twin-scroll turbocharged engine are asymmetrically and periodically complicated, which has great impact on turbine matching. In this article, a matching effect of turbine speed parameter on asymmetric twin-scroll turbines based on the exhaust pulse energy weight distribution of a heavy-duty diesel engine was introduced. First, it was built as an asymmetric twin-scroll turbine matching based on exhaust pulse energy distribution. Then, by comparing the average matching point and energy matching points on the corresponding turbine performance map, it is revealed that the turbine speed parameter of energy matching points was a significant deviation from the turbine speed parameter under peak efficiency, which leads to the actual turbine operating efficiency lower than the optimal state.

Abstract NVH refinement of commercial vehicles is the key attribute for customer acceptance. Engine and road irregularities are the two major factors responsible for the same. During powertrain isolators’ design alone, the mass and inertia of the powertrain are usually considered, but in practical scenarios, a directly coupled subsystem also disturbs the boundary conditions for design. Due to the upgradation in emission norms, the exhaust aftertreatment system of modern automotive vehicles becomes heavier and more complex. This system is further coupled to the powertrain through a flexible joint or fixed joint, which results in the disturbance of the performance of the isolators. Therefore, to address this, the isolators design study is done by considering a multi-body dynamics model of vehicles with 16 DOF and 22 DOF problems, which is capable to simulate static and dynamic real-life events of vehicles.

Abstract Heavy-duty on-road engines are expected to conform to an ultralow NOx (ULNOx) standard of 0.027 g/kWh over the composite US heavy-duty transient federal test procedure (HD-FTP) cycle by 2031, a 90% reduction compared to 2010 emissions standards. Additionally, these engines are expected to conform to Phase 2 greenhouse gas regulations, which require tailpipe CO2 emissions under 579 g/kWh. This study experimentally demonstrates the ability of high fuel stratification gasoline compression ignition (HFS-GCI) to satisfy these emissions standards. Steady-state and transient tests are conducted on a prototype multi-cylinder heavy-duty GCI engine based on a 2010-compliant Cummins ISX15 diesel engine with a urea-SCR aftertreatment system (ATS). Steady-state calibration exercises are undertaken to develop highly fuel-efficient GCI calibration maps at both cold-start and warmed up conditions.

Abstract Improving thermal efficiency of an internal combustion engine is one of the most cost-effective ways to reduce life cycle-based CO2 emissions for transportation. Lean burn technology has the potential to reach high thermal efficiency if simultaneous low NOx, HC, and CO emissions can be achieved. Low NOx can be realized by ultra-lean (λ ≥ 2) spark-ignited combustion; however, the HC and CO emissions can increase due to slow flame propagation and high combustion variability. In this work, we introduce a new combustion concept called turbulent jet-controlled compression ignition, which utilizes multiple turbulent jets to ignite the mixture and subsequently triggers end gas autoignition. As a result, the ultra-lean combustion is further improved with reduced late-cycle combustion duration and enhanced HC and CO oxidation. A low-cost passive prechamber is innovatively fueled using a DI injector in the main combustion chamber through spray-guided stratification.

Abstract Despite the growing prominence of electrified vehicles, internal combustion engines remain essential in future transportation. This study delves into passive pre-chamber jet ignition, a leading-edge combustion technology, offering a comprehensive visualization of its operation under varying load and dilution conditions in light-duty GDI engines. Our primary objectives are to gain fundamental insights into passive pre-chamber jet ignition and subsequent main combustion processes and evaluate their response to different load and dilution conditions. We conducted experimental investigations using a light-duty, optical, single-cylinder engine equipped with three passive pre-chamber designs featuring varying nozzle diameters. Optical diagnostic imaging and heat release analysis provided critical insights.

Abstract Recent legislations require very low soot emissions downstream of the particulate filter in diesel vehicles. It will be difficult to meet the new more stringent OBD requirements with standard diagnostic methods based on differential sensors. The use of inexpensive and reliable soot sensors has become the focus of several academic and industrial works over the past decade. In this context, several diagnostic strategies have been developed to detect DPF malfunction based on the soot sensor loading time. This work proposes an advanced online diagnostic method based on soot sensor signal projection. The proposed method is model-free and exclusively uses soot sensor signal without the need for subsystem models or to estimate engine-out soot emissions. It provides a comprehensive and efficient filter monitoring scheme with light calibration efforts.

Abstract Greenhouse gas emissions reduction from the light-duty transportation fleet is urgent and should address both electric and conventional powertrain technologies. Internal combustion engines will continue to be employed for vehicle propulsion and fleet turnover is slow, encouraging reduction of carbon content in gasoline. Currently ethanol, a renewable fuel, is blended at the 10% level into petroleum to produce finished market gasoline. Ethanol enables a less carbon-intensive petroleum blendstock composition, providing for additional reduction, but this is often overlooked in studies. Carbon intensity, as a ratio of CO2 mass to heat released upon combustion, is a measure of well-to-wheels greenhouse gas production. The well-to-wheels carbon intensity of ethanol does not include its chemical carbon content because it arises from a renewable source, but does consider all upstream farming, production, and transportation carbon impacts.

Abstract Methanol is emerging as an alternate internal combustion engine fuel. It is getting attention in countries such as China and India as an emerging transport fuel. Using methanol in spark ignition engines is easier and more economical than in compression ignition engines via the blending approach. M85 (85% v/v methanol and 15% v/v gasoline) is one of the preferred blends with the highest methanol concentration. However, its physicochemical properties significantly differ from gasoline, leading to challenges in operating existing vehicles. This experimental study addresses the challenges such as cold-start operation and poor throttle response of M85-fueled motorcycle using a port fuel injection engine. In this study, M85-fueled motorcycle prototype is developed with superior performance, similar/better drivability, and lower emissions than a gasoline-fueled port-fuel-injected motorcycle.

Abstract Turbocharged spark-ignition (SI) engines, owing to frequent engine knocking events, utilize retarded spark timing that causes combustion inefficiency, and high turbine inlet temperature (Trb-In T) levels. Fuel enrichment is implemented at high power levels to prevent excessive Trb-In T levels, resulting in an additional fueling penalty and higher CO emissions. In current times, fuel-enrichment reductions are of high strategic importance for engine manufacturers to meet the imminent emissions regulations. To that end, the authors investigated the divided exhaust period (DEP) concept in a 2.2 L turbocharged SI engine with a geometric compression ratio of 14 by decoupling blowdown (BD) and scavenge (SC) events during the exhaust process. Using a validated 1D engine model, the authors first analyzed the DEP concept in terms of pumping mean effective pressure (PMEP) and engine knocking (KI) reduction.

Abstract Tank-to-wheels (TTW) CO2 reduction for ethanol blends is determined from either gasoline composition or vehicle exhaust measurements. Fuels are characterized using a carbon intensity (CI), which is the ratio of carbon (as CO2 mass) in the fuel to the net heating value. Our objective is to assess changes in CI of market gasoline with varying ethanol content that can be used to appreciate change in vehicle tailpipe greenhouse gases (GHG) in response to policy controlling the ethanol level in market fuels. Ethanol has both a reduced carbon content and a reduced net (lower) heating value relative to petroleum species, with a CI slightly lower than that of typical petroleum gasoline. However, ethanol blending offers additional CI reduction because it enables a reduction of aromatics in the petroleum blendstock for oxygenate blending (BOB) while maintaining octane rating of the blend. Aromatics have a CI about 20% higher than paraffins.

Abstract This study investigates the behavior of pre-chamber knock in comparison to traditional spark ignition engine knock, using a modified constant-volume gasoline engine with an optically accessible piston. The aim is to provide a deeper understanding of pre-chamber knock combustion and its potential for mitigating knock. Five passive pre-chambers with different nozzle diameters, volumes, and nozzle numbers were tested, and nitrogen dilution was varied from 0% to 10%. The stochastic nature of knock behavior necessitates the use of statistical methods, leading to the proposal of a high-frequency band-pass filter (37–43 kHz) as an alternative pre-chamber knock metric. Pre-chamber knock combustion was found to exhibit fewer strong knock cycles compared to SI engines, indicating its potential for mitigating knock intensity. High-speed images revealed pre-chamber knock primarily occurs near the liner, where end-gas knock is typically exhibited.

Abstract Research into efficient internal combustion (IC) engines need to continue as the majority of vehicles will still be powered by IC or hybrid powertrains in the foreseeable future. Recently, lean-burn gasoline compression ignition (GCI) with high-pressure direct injection has been receiving considerable attention among the research community due to its ability to improve thermal efficiency and reduce emissions. To maximize GCI benefits in engine efficiency and emissions tradeoff, co-optimization of the combustion system and fuel formation is required. Thus, it is essential to study the spray characteristics of different fuels under engine-like operating conditions. In this work, high-pressure spray characteristics are experimentally studied for three blends of gasoline, namely, Naphtha, E30, and research octane number (RON) 98. A single-hole custom-built injector was used to inject fuel into a constant volume chamber with injection pressure varying from 40 MPa to 100 MPa.

Abstract Pre-chamber jet ignition technologies have been garnering significant interest in the internal combustion engine field, given their potential to deliver shorter burn durations, increased combustion stability, and improved dilution tolerance. However, a clear understanding of the relationship between pre-chamber geometry, operating condition, jet formation, and engine performance in light-duty gasoline injection engines remains under-explored. Moreover, research specifically focusing on high dilution levels and passive pre-chambers with optical accessibility is notably scarce. This study serves to bridge these knowledge gaps by examining the influence of passive pre-chamber nozzle diameter and dilution level on jet formation and engine performance.

Abstract The use of data-driven algorithms for the integration or substitution of current production sensors is becoming a consolidated trend in research and development in the automotive field. Due to the large number of variables and scenarios to consider; however, it is of paramount importance to define a consistent methodology accounting for uncertainty evaluations and preprocessing steps, that are often overlooked in naïve implementations. Among the potential applications, the use of virtual sensors for the analysis of solid emissions in transient cycles is particularly appealing for industrial applications, considering the new legislations scenario and the fact that, to our best knowledge, no robust models have been previously developed.

Abstract To have a more complete understanding of the fuel effects on each subsequent stage of a stochastic preignition event in a spark-ignition engine and to build on the previous work of understanding the propensity of fuel to initiate and sustain a preignition flame, this work is focused on examining the role of fuel on the onset of knock and the intensity of superknock once the unburned mixture reaches certain conditions ahead of the preignition flame. Using a “skip advance” spark test method to simulate preignition flames initiated at different cylinder conditions, more than 20 single- and multicomponent fuels were ranked based on the condition required to reach the onset of knock (the start of end-gas autoignition) and the condition that leads to severe superknock intensities.

Abstract Pre-chamber turbulent jet ignition (TJI) is a method of generating distributed ignition sites through multiple high-speed turbulent jets in order to achieve an enhanced burn rate in the engine cylinder when compared to conventional spark plug ignition. To study the gas-dynamic interactions between the two chambers in a gasoline engine, a three-dimensional numerical model was developed using the commercial CFD code CONVERGE. The geometry and parameters of the engine used were based on a modified turbocharged GM four-cylinder 2.0 L GDI gasoline engine. Pre-chambers with nozzle diameters of 0.75 mm and 1.5 mm were used to investigate the effect of pre-chamber geometry on pre-chamber charging, combustion, and jet formation. The local developments of gas temperature and velocity were captured by adaptive mesh refinement, while the turbulence was resolved with the k-epsilon model of the Reynolds averaged Navier–Stokes (RANS) equations.

Abstract In the last few years, the artificial neural networks have been widely used in the field of engine modeling. Some of the main reasons for this are, their compatibility with the real-time systems, higher accuracy, and flexibility if compared to other data-driven approaches. One of the main difficulties of using this approach is the calibration of the network itself. It is very difficult to find in the literature procedures that guide the user to completely define a network. Typically, the very last steps (like the choice of the number of neurons) must be selected by the user on the base of his sensitivity to the problem.

Abstract Quantifying exhaust gas composition and temperature in vehicles with internal combustion engines (ICEs) is crucial to understanding and reducing emissions during transient engine operation. This is particularly important before the catalytic converter system lights off (i.e., during cold start). Most commercially available gas analyzers and temperature sensors are far too slow to measure these quantities on the timescale of individual cylinder-firing events, thus faster sensors are needed. A two-color mid-infrared (MIR) laser absorption spectroscopy (LAS) sensor for gas temperature and carbon monoxide (CO) mole fraction was developed and applied to address this technology gap. Two quantum cascade lasers (QCLs) were fiber coupled into one single-mode fiber to facilitate optical access in the test vehicle exhaust. The QCLs were time-multiplexed in order to scan across two CO absorption transitions near 2013 and 2060 cm–1 at 15 kHz.