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Technical Paper

Evaluation of an On-board, Real-time Electronic Particulate Matter Sensor Using Heavy-duty On-highway Diesel Engine Platform

2020-04-14
2020-01-0385
California Air Resources Board (CARB) has instituted requirements for on-board diagnostics (OBD) that makes a spark-plug sized particulate matter (PM) sensor a critical component of the OBD system to detect diesel particulate filter (DPF) failure. Current PM OBD thresholds for heavy-duty on-highway vehicles is 0.03 g/hp-hr and for light-duty vehicles (2019+ Model Year LEV III) is 17.5 mg/mile. To meet these regulations, and more stringent future regulations, real-time PM sensors offer numerous benefits over traditional accumulation type resistive sensors. The focus of this work is on the experimental evaluation of such a real-time PM sensing technology manufactured by CoorsTek LLC. A 2011 model year on-highway heavy-duty diesel engine fitted with diesel oxidation catalyst/diesel particulate filter/selective catalytic reducer/ammonia oxidation catalyst (DOC/DPF/SCR/AMOX) was used for the evaluation program.
Technical Paper

Investigation Into Improved Low-Temperature Urea-Water Solution Decomposition by Addition of Titanium-Based Isocyanic Acid Hydrolysis Catalysts and Surfactant

2020-04-14
2020-01-1316
Mitigation of urea deposit formation and improved ammonia production at low exhaust temperatures continues to be one of the most significant challenges for current generation SCR aftertreatment systems. Various technologies have been devised to alleviate these issues including: use of alternative reductant sources and thermal treatment of the urea-water solution (UWS) pre-injection. The objective of this work is to expand the knowledge base of a potential third option, which entails chemical modification of UWS by addition of titanium-based urea/isocyanic acid (HNCO) decomposition catalysts and/or surfactants to the fluid. Physical mixtures of urea and varying concentrations of ammonium titanyl oxalate (ATO), oxalic acid, and titanium dioxide (TiO2) were generated, and the differences in NH3 and CO2 production were evaluated.
Technical Paper

Opportunities for Electrified IC Engines

2020-04-14
2020-01-0281
The automotive industry is polarized between external pressures for ‘zero’ emission battery electric vehicles (BEV) and the ability to manufacture them economically and with minimal environmental impact. Most predictions of future BEV market share suggest that the IC engine has an important role to play in personal transportation for the next several decades. That engine will very likely be part of a hybrid architecture. Accepting that the engine will be part of a hybrid powertrain permits new design rules and strategies for the IC engine. A major characteristic change of the engine will be to reduce BMEP, power density and engine speed requirements as performance demand will be supplemented by electric machines. This paper focuses on some simple changes to the IC engine to increase thermal efficiency with the knowledge of the supplemental electric energy.
Technical Paper

CARB Low NOx Stage 3 Program – Modified Engine Calibration and Hardware Evaluations

2020-04-14
2020-01-0318
With the conclusion of the California Air Resources Board (CARB) Stage 1 Ultra-Low NOX program, there continues to be a commitment for identifying potential pathways to demonstrate 0.02 g/bhp-hr NOX emissions. The Stage 1 program focused on achieving the Ultra-Low NOX (ULN) levels on the heavy-duty regulatory cycles utilizing a turbo-compound (TC) engine, which required the integration of novel catalyst technologies and a supplemental heat source. While the aftertreatment configuration provided a potential solution to meet the ULN target, a complicated approach was required to overcome challenges from low temperature exhaust. The Stage 2 program was concerned with the development of a new low load test cycle and evaluating the trade-off between GHG and tailpipe NOx on the Stage 2 ULN solution.
Technical Paper

Development and demonstration of a class 6 range-extended electric vehicle for commercial pickup and delivery operation

2020-04-14
2020-01-0848
Range-extended hybrids are an attractive option for medium- and heavy-duty (M/HD) commercial vehicle fleets because they offer the efficiency of an electrified powertrain and accessories with the range of a conventional diesel powertrain. The vehicle essentially operates as if it was purely electric for most trips, while ensuring that all commercial routes can be completed in any weather conditions or geographic terrain. Fuel use and point-source emissions can be significantly reduced, and in some cases eliminated, as many shorter routes can be fully electrified with this architecture. Under a U.S. Department of Energy award for M/HD Vehicle Powertrain Electrification, Cummins has developed a plug-in hybrid electric (PHEV) class 6 truck with a range-extending engine designed for pickup and delivery application. The National Renewable Energy Laboratory (NREL) assisted by developing a representative work day drive cycle for class 6 operation and adapting it to enable track testing.
Technical Paper

Use of Nitric Acid to Control the NO2:NOX Ratio Within the Exhaust Composition Transient Operation Laboratory Exhaust Stream

2020-04-14
2020-01-0371
The Exhaust Composition Transient Operation Laboratory (ECTO-Lab) is a burner system developed at Southwest Research Institute (SwRI) for simulation of IC engine exhaust. The current system design requires metering and combustion of nitromethane in conjunction with the primary fuel source as the means of NOX generation. While this method affords highly tunable NOX concentrations even over transient cycles, no method is currently in place for dictating the speciation of nitric oxide (NO) and nitrogen dioxide (NO2) that constitute the NOX mixture. NOX generated through combustion of nitromethane is dominated by NO, and generally results in a NO2:NOX ratio of <5 %. Generation of any appreciable quantities of NO2 is therefore dependent on an oxidation catalyst to oxidize a fraction of the NO to NO2.
Technical Paper

CARB Low NOX Stage 3 Program - Aftertreatment Evaluation and Down Selection

2020-04-14
2020-01-1402
With the conclusion of the California Air Resources Board (CARB) Stage 1 Ultra-Low NOX program, there continues to be a commitment for identifying potential pathways to demonstrate 0.02 g/bhp-hr NOX emissions. The Stage 1 program focused on achieving the Ultra-Low NOX (ULN) levels utilizing a turbo-compound (TC) engine, which required the integration of novel catalyst technologies and a supplemental heat source. While the aftertreatment configuration provided a potential solution to meet the ULN target, a complicated approach was required to overcome challenges from low temperature exhaust. The Stage 3 program leverages a different engine architecture more representative of the broader heavy-duty industry to meet the Phase 2 GHG targets and to simplify the ULN aftertreatment solution.
Technical Paper

Evaluation of Cylinder Deactivation on a Class 8 Truck over Light Load Cycles

2020-04-14
2020-01-0800
Selective Catalytic Reduction (SCR) systems provide excellent NOx control for diesel engines provided the exhaust inlet temperature remains 200 degrees C or higher. Since diesel engines run lean, extended light load operation typically causes exhaust temperatures to fall below 200 degrees C and SCR conversion efficiency diminishes. Heated urea dosing systems are being developed to allow dosing below 190 degrees C. However, catalyst face plugging remains a concern. Close coupled SCR systems and lower temperature formulation of SCR systems are also being developed. Current strategies of post fuel injection and retarded injection timing increases fuel consumption. One viable keep-warm strategy examined in this paper is cylinder deactivation (CDA) which can increase exhaust temperature and reduce fuel consumption.
Technical Paper

Portable In-cylinder Pressure Measurement and Signal Processing System for Real-time Combustion Analysis and Engine Control

2020-04-14
2020-01-1144
To meet ever strict emissions regulations, cycle-to-cycle combustion control based on statistical processing and model-based prediction has attracted considerable attention from academia and industry. Feedback combustion control typically adjusts ignition-related parameters (spark advance, injection timing, cam timing, etc.) in a cycle-by-cycle manner based on the combustion characteristics measured from previous events. Cycle-to-cycle control guarantees a tight control at steady state and fast response during transients, enforcing an optimal combustion process over a wide variety of engine speed/load conditions. However, these control strategies are constrained by the combustion cycle duration, usually in the order of tens of milliseconds. Therefore, high-speed data acquisition and real-time processing is required.
Technical Paper

Electronic Control of Brake and Accelerator Pedals for Precise Efficiency Testing of Electrified Vehicles

2020-04-14
2020-01-1282
Efficiency testing of hybrid-electric vehicles is challenging, because small run-to-run differences in pedal application can change when the engine fires or the when the friction brakes supplement regenerative braking, dramatically affecting fuel use or energy regeneration. Electronic accelerator control has existed for years, thanks to the popularity of throttle-by-wire (TBW). Electronic braking control is less mature, since most vehicles don’t use brake-by-wire (BBW). Computer braking control typically uses a mechanical actuator (which may suffer backlash or misalignment) or braking the dynamometer rather than the vehicle (which doesn’t yield regeneration). The growth of electrification and autonomy provides the means to implement electronic brake control. Electrified vehicles use BBW to control the split between friction and regenerative braking. Automated features, e.g. adaptive cruise control, require BBW to actuate the brakes without pedal input.
Technical Paper

Combined Benefits of Variable Valve Actuation and Low-Pressure EGR on SI Engine Efficiency Part 1: Part Load

2019-04-02
2019-01-0241
Modern spark ignited engines face multiple barriers to achieving higher thermal efficiency. This study investigated the potential of utilizing both continuously variable valve actuation (VVA) and low-pressure cooled exhaust gas recirculation (EGR) to improve engine thermal efficiency at part-load conditions. Six speed / load points were investigated on a 1.6 L turbocharged gasoline direct injection engine. A design of experiment (DoE) approach using the Box-Behnken surface response model was conducted. The DoE results revealed different brake specific fuel consumption (BSFC) responses to the valve phasing and the intake valve lift at different operating conditions. Further engine testing was carried out at each speed / load point to confirm the engine efficiency and combustion performance when targeting different valvetrain controls and EGR strategies. The results indicated that utilizing the VVA system could always reduce BSFC at the studied operating conditions.
Technical Paper

Combined Benefits of Variable Valve Actuation and Low-Pressure EGR on SI Engine Efficiency Part 2: High Load

2019-04-02
2019-01-0237
The abnormal autoignition of the unburned gas, namely knock, at high loads is a major challenge for modern spark ignited engines. Knock prevents the application of high compression ratios due to the increased unburned gas temperature, and it becomes increasingly severe for downsized engines with high specific powers. The current paper reports on the potential of utilizing continuously variable valve actuation (VVA) and low-pressure exhaust gas recirculation (EGR) to reduce knock tendency at high loads. Five speed / load points were investigated on a 1.6 L turbocharged gasoline direct injection engine. The brake specific fuel consumption (BSFC) response to the valve phasing and the intake valve lift was investigated with the design of experiment (DoE) approach. The DoE was conducted using a Box-Behnken surface response model. The results exhibited insensitive response of BSFC to intake valve lift and overlap.
Technical Paper

An Exploratory Look at an Aggressive Miller Cycle for High BMEP Heavy-Duty Diesel Engines

2019-04-02
2019-01-0231
Through aggressive application of the Miller Cycle, using two-stage turbocharging, medium speed diesel marine and stationary power engines are demonstrating over 30 bar rated power BMEP, and over 50 percent brake thermal efficiency. The objective of this work was to use engine cycle simulation to assess the degree to which the aggressive application of the Miller Cycle could be scaled to displacements and speeds more typical of medium and heavy truck engines. A 9.2 liter six-cylinder diesel engine was modeled. Without increasing the peak cylinder pressure, improved efficiency and increased BMEP was demonstrated. The level of improvement was highly dependent on turbocharger efficiency - perhaps the most difficult parameter to scale from the larger engines. At 1600 rpm, and a combined turbocharger efficiency of 61 percent, the baseline BMEP of 24 bar was increased to over 26 bar, with a two percent fuel consumption improvement.
Technical Paper

A Comprehensive CFD-FEA Conjugate Heat Transfer Analysis for Diesel and Gasoline Engines

2019-04-02
2019-01-0212
As the efforts to push capabilities of current engine hardware to their durability limits increases, more accurate and reliable analysis is necessary to ensure that designs are robust. This paper evaluates a method of Conjugate Heat Transfer (CHT) analysis for a gasoline and a diesel engine that combines combustion Computational Fluid Dynamics (CFD), engine Finite Element Analysis (FEA), and cooling jacket CFD with the goal of obtaining more accurate temperature distribution and heat loss predictions in an engine compared to standard de-coupled CFD and FEA analysis methods. This novel CHT technique was successfully applied to a 2.5 liter GM LHU gasoline engine at 3000 rpm and a 15.0 liter Cummins ISX heavy duty diesel engine operating at 1250 rpm. Combustion CFD simulations results for the gasoline and diesel engines are validated with the experimental data for cylinder pressure and heat release rate.
Technical Paper

Deposit Reduction in SCR Aftertreatment Systems by Addition of Ti-Based Coordination Complex to UWS

2019-04-02
2019-01-0313
Formation of urea-derived deposits in selective catalytic reduction (SCR) aftertreatment systems continues to be problematic at temperatures at and below 215 °C. Several consequences of deposit formation include: NOx and NH3 slip, exhaust flow maldistribution, increased engine backpressure, and corrosion of aftertreatment components. Numerous methods have been developed to reduce deposit formation, but to date, there has been no solution for continuous low-temperature dosing of Urea-Water Solution (UWS). This manuscript presents a novel methodology for reducing low-temperature deposit formation in SCR aftertreatment systems. The methodology described herein involves incorporation and dissolution of an HNCO hydrolysis catalyst directly into the UWS. HNCO is a transient species formed by the thermolysis of urea upon injection of UWS into the aftertreatment system.
Technical Paper

Particle Emissions from Gasoline Direct Injection Engines during Engine Start-Up (Cranking)

2019-04-02
2019-01-1182
Engine start-up (cranking) can be an important source of particle emissions from vehicles. With the penetration of GDI vehicles in the global vehicle fleet, it is important to analyze and understand the contribution of start-up particle emissions from GDI vehicles, and the potential effects of fuel properties on that process. In this work, chassis dynamometer based investigation on the effect of several gasoline fuels (commercial and blended) on both, naturally aspirated and turbocharged GDI vehicles were conducted to understand the importance of engine start up, in particular, cranking. 10 commercially available gasoline fuels were tested on a naturally aspirated 2010 model year GDI vehicle, 3 among these commercially available fuels were tested on another 2009 model year turbocharged GDI vehicle, and 8 blended gasoline fuels were tested on 12 other GDI vehicles (7 turbocharged and 5 naturally aspirated) ranging in model years 2011-2015.
Journal Article

Benchmarking a 2018 Toyota Camry 2.5-Liter Atkinson Cycle Engine with Cooled-EGR

2019-04-02
2019-01-0249
As part of the U.S. Environmental Protection Agency’s (EPA’s) continuing assessment of advanced light-duty automotive technologies in support of regulatory and compliance programs, a 2018 Toyota Camry A25A-FKS 4-cylinder, 2.5-liter, naturally aspirated, Atkinson Cycle engine with cooled exhaust gas recirculation (cEGR) was benchmarked. The engine was tested on an engine dynamometer with and without its 8-speed automatic transmission, and with the engine wiring harness tethered to a complete vehicle parked outside of the test cell. Engine and transmission torque, fuel flow, key engine temperatures and pressures, onboard diagnostics (OBD) data, and Controller Area Network (CAN) bus data were recorded. This paper documents the test results under idle, low, medium, and high load engine operation. Motoring torque, wide open throttle (WOT) torque and fuel consumption are measured during transient operation using both EPA Tier 2 and Tier 3 test fuels.
Technical Paper

Effects of Dual Port Injection and Direct-Injection Technology on Combustion Emissions from Light-Duty Gasoline Vehicles

2019-04-02
2019-01-0999
Dual injection fuel systems combine the knock and fuel economy benefits of gasoline direct injection (GDI) technology with the lower particulate emissions of port fuel injection (PFI) systems. For many years, this technology was limited to smaller-volume, high-end, vehicle models, but these technologies are now becoming main stream. The combination of two fuel injection systems has an impact on the combustion emission composition as well as the consistency of control strategy and emissions. Understanding the impact of these changes is essential for fuel and fuel additive companies, automotive companies, and aftertreatment developers. This paper describes the effects of dual injection technology on both regulated and non-regulated combustion emissions from a 2018 Toyota Camry during several cold-start, 4-bag United States Federal Test Procedure (FTP) cycle.
Technical Paper

Fuel Reforming and Catalyst Deactivation Investigated in Real Exhaust Environment

2019-04-02
2019-01-0315
Increased in-cylinder hydrogen levels have been shown to improve burn durations, combustion stability, HC emissions and knock resistance which can directly translate into enhanced engine efficiency. External fuel reformation can also be used to increase the hydrogen yield. During the High-Efficiency, Dilute Gasoline Engine (HEDGE) consortium at Southwest Research Institute (SwRI), the potential of increased hydrogen production in a dedicated-exhaust gas recirculation (D-EGR) engine was evaluated exploiting the water gas shift (WGS) and steam reformation (SR) reactions. It was found that neither approach could produce sustained hydrogen enrichment in a real exhaust environment, even while utilizing a lean-rich switching regeneration strategy. Platinum group metal (PGM) and Ni WGS catalysts were tested with a focus on hydrogen production and catalyst durability.
Technical Paper

Review of the Computer Science and Engineering Solutions for Model Sharing and Model Co-Simulation

2019-03-19
2019-01-1352
The process of developing, parameterizing, validating, and maintaining models occurs within a wide variety of tools, and requires significant time and resources. To maximize model utilization, models are often shared between various toolsets and experts. One common example is sharing aircraft engine models with airframers. The functionality of a given model may be utilized and shared with a secondary model, or multiple models may run collaboratively through co-simulation. There are many technical challenges associated with model sharing and co-simulation. For example, data communication between models and tools must be accurate and reliable, and the model usage must be well-documented and perspicuous for a user. This requires clear communication and understanding between computer scientists and engineers. Most often, models are developed by engineers, whereas the tools used to share the models are developed by computer scientists.
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