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Technical Paper

Emission control system designing of the GDI vehicle for China6 regulation

2018-09-10
2018-01-1706
China6 is going to be implemented from Jul 1, 2020, and China6b limits decreased nearly half against China5, plus introduce PN limit, 6*1011#/kg, it is very challenge because of the stringent requirement. In this paper, one development stage vehicle, equipped with 1.5TGDI engine, was chosen for system designing. After calibration modification, 3 kinds of TWC systems with variable PGM loading, were evaluated and the middle proposal can pass the target under both fresh and engine aged condition. Moreover, GPF system was also introduced to further reduced particle emission. Compared to TWC system, GPF system maintain the comparable TWC performance, however achieved a 50% and nearly 95% filtration efficiency under fresh and aged condition separately, can fully meet China6b requirement. Finally, soot accumulation and regeneration in GPF were also investigated under variable ambient temperature and diving condition.
Technical Paper

A Simulation Study of the Optimal Integration of a Rankine Cycle Based Waste Heat Recovery System into the Cooling System of a Long-Haul Heavy Duty Truck

2018-09-10
2018-01-1779
As a promising solution to improve fuel efficiency of a long-haul heavy duty truck with diesel en-gine, organic Rankine cycle (ORC) based waste heat recovery system (WHR) by utilizing the ex-haust gas from internal combustion engine has continuously drawn attention from automobile industry in recent years. The most attractive concept of ORC-based WHR-System is the conversion of the energy of exhaust gas recirculation (EGR) and exhaust gas from Tailpipe (EGT) to mechanical energy which is refed to the engine crankshaft. Due to the shift of the operating point of the engine by applying WHR-System, the efficiency of the global system will be increased and the fuel consumption can be reduced. However, the integration is challenging by using the cooling system of the Truck as the heat sink of the Rankine Cycle.
Technical Paper

Study of turbulent entrainment quasi-dimensional combustion model of HCNG engines with variable ignition timings

2018-09-10
2018-01-1687
Abstract: Presently, urban transportation highly depends on the fossil fuels, but its rapid fluctuating economic issues and environmental consequences impose the variegation of energy sources. Hydrogen enriched compressed natural gas (HCNG) engines offer the potential of higher brake thermal efficiency with low emissions, which also satisfies the strict pollutant emission standards. The two-zone turbulent entrainment quasi-dimensional combustion model is developed to predict the combustion process of spark-ignited hydrogen enriched compressed natural gas-fueled engines. The fundamentals of thermodynamic process, turbulent flame propagation model and other sub-models like laminar burning velocity, adiabatic temperature and ignition lag model are introduced for the better accuracy. The experiments have been conducted for three different fuels; pure CNG, 20% HCNG, and 40% HCNG blends under MAP of 105 kPa for the various excess air ratio (λ), ignition timing (θi).
Technical Paper

Fuel Economy Regulations and Technology Roadmaps of China and the US: Comparison and Outlook

2018-09-10
2018-01-1826
In order to address the increasing energy and environmental concerns, China and the US both launched the fuel economy regulations and aim to push the development of technology. In this study, the stringency of CAFC and CAFE regulations and the technology development of two countries are compared. Besides, the optimal technology pathways of America and automakers for the compliance of CAFE regulations are calculated based on the modified VOLPE model, and the results are used as reference for China. The results indicate that the annual regulation improvement rates of China is higher than America and the AIR of China 2015-2020 regulation reaches 6.2% and is the most stringent phase in 10 years from 2015 to 2025. From the perspective of technology, there are still big gaps between China and the US in the applications of advanced fuel saving technologies.
Technical Paper

Study of Interaction Between N-Methyl Aniline Octane Booster and Lubricating oil

2018-09-10
2018-01-1809
The impact of N-Methyl Aniline (NMA) octane booster on lubricating oil has previously been studied and the main findings were reported in SAE paper 2016-01-2273. Increased sludge formation had been observed in modified ACEA black sludge testing when NMA was added to the fuel but there was very limited viscosity increase, which did not corroborate the trend evidenced on modified CEC L-109 oxidation testing where significant viscosity increase was noted when NMA was added to the oil and fuel mixture. Accordingly, modified black sludge tests have been run with and without NMA added to the oil sump at the beginning of the test to better match modified L-109 oxidation bench test conditions. Results showed the same trend in terms of viscosity increase between the modified L-109 oxidation bench test and black sludge test.
Technical Paper

Evaluation of Engine Programming to Reduce Fuel Consumption

2018-09-10
2018-01-1757
The goal of this pilot project was to evaluate the potential for reducing the fuel consumption of heavy-duty vehicles through an approach aimed at the optimal programming of engine electronic control units. This paper summarizes all of the activities, observations and results related to track testing to compare default programming with economical optimized programming. For long-distance and regional transport fuel consumption tests at constant speed based on the SAE J1321 were conducted, as well as fuel consumption tests using a towing dynamometer to simulate various road profiles. For urban transport and specialized transport the tests were carried out on specific work cycles. For tests with school buses carried out during stop-and-go cycles, fuel savings of up to 5% are achieved, depending on the cycle, test vehicle and driving technique.
Technical Paper

Performance and Exhaust Emissions Analysis of a Diesel Engine using Oxygen-Enriched Air

2018-09-10
2018-01-1785
The paper explores, by means of 3D CFD simulations, the effects of Oxygen-Enriched Air on performance and exhaust emissions of a High Speed Direct Injection (HSDI) Diesel engine. For the analysis, a customized version of the KIVA 3V code, including a detailed combustion chemistry approach, coupled with a comprehensive oxidation mechanism for diesel oil surrogate, has been used. A current production 2.8 L4-cylinder engine was selected and available experimental test data were used for validation of the engine model in terms of both combustion characteristics and exhaust emissions. Oxygen-Enriched Air production has been also considered and different solutions have been compared. Using the calibrated engine model, the effects of Enriched Air was investigated, along with the influence of injection strategies, at different operating conditions. It was found that Oxygen-Enriched combustion reduces Soot emissions and improves engine thermal efficiency, but also increases NO emissions.
Technical Paper

Bowl geometry effects on turbulent flow structure in a direct injection diesel engine

2018-09-10
2018-01-1794
In swirl-supported diesel engines, piston bowl geometry can affect mixing controlled heat release rates and thereby thermal efficiency. These effects may also depend on parameters such as injection timing, engine speed, and load, but a fundamental understanding of how bowl geometry and injection timing/duration influence turbulent mixing rates is lacking. This computational study compares engine behavior with two pistons representing competing approaches to combustion chamber design: a conventional, re-entrant piston bowl and a stepped-lip piston bowl. Simulations are performed for a conventional diesel combustion operating point with a pilot-main injection strategy under non-combusting conditions. Injection timing and duration are varied and the simulation results are analyzed to provide insight into bowl geometry effects on turbulent flow structure and mixing behavior.
Technical Paper

On-Road Monitoring of Low Speed Pre-Ignition

2018-09-10
2018-01-1676
To meet increasingly stringent emissions and fuel economy regulations, many Original Equipment Manufacturers (OEMs) have recently developed and deployed small, high power density engines. Turbocharging, coupled with gasoline direct injection (GDI) has enabled a rapid engine downsizing trend. While these turbocharged GDI (TGDI) engines have indeed allowed for better fuel economy in many light duty vehicles, TGDI technology has also led to some unintended consequences. The most notable of these is an abnormal combustion phenomenon known as Low Speed Pre-Ignition (LSPI). LSPI is an uncontrolled combustion event that takes place prior to the spark ignition and has been known to cause catastrophic engine damage. LSPI propensity depends on a number of factors including engine design, calibration, fuel properties and engine oil formulation. Several engine tests have been developed within the industry to better understand the phenomenon of LSPI.
Technical Paper

New GKI – Gasoline Knock Index for rating of Fuel´s Knock Resistance on an upgraded CFR Test Engine

2018-09-10
2018-01-1743
In terms of international efforts for reducing CO2-emission, the thermal efficiency of SI engines as the worldwide dominating power source for private transport needs to be increased. One key enabler to achieve this target is the availability of a highly knock-resistant fuel: it allows to break up the trade-off between elevated compression ratio demanded for high part-load efficiency and a reduced knock tendency at high engine loads by a minimized requirement for an efficiency-killing spark retard. In view to the world´s fuel map, which is dominated nowadays by qualities between 91 and 98 RON, there is a beginning transition towards increased knock resistance (above 100 RON) being observed in several countries. The corresponding standards for engine-based fuel quality rating (e.g. ASTM D2699) provide a RON scale covering the range from 40 to 120.3, which basically seems to be enough.
Technical Paper

Design and Development of a Roller Follower Hydraulic Lash Adjustor to Eliminate Lash Adjustment and Reduce Noise in a Serial Production Diesel Engine

2018-09-10
2018-01-1766
Commercial vehicles require continual improvements in order to meet fuel emission standards, improve diesel aftertreatment system performance and optimize vehicle fuel economy. Aftertreatment systems require significant space claim which makes vehicle packaging a challenge. Today’s diesel engines required valvetrain lash adjustment settings at distinct intervals to ensure proper valvetrain performance. This requires removing the engine rocker cover to set lash in order to access the valvetrain rocker arms. Setting lash for compact vehicle applications sometimes requires removing the aftertreatment system in order to remove the rocker cover prior to setting lash. Then, the rocker cover is reinstalled followed by the aftertreatment system making the lash setting process time consuming and complex.
Technical Paper

Effect of Fuel Injection Strategy on Nano-particle Emissions from RCCI Engine

2018-09-10
2018-01-1709
Increase in the air pollution in past decades has driven the research towards the cleaner combustion technology for automobile engines. To tackle the challenge of the trade-off between the NOx and soot emission in conventional diesel combustion (CDC) engine, premixed low-temperature combustion (LTC) strategy is a promising approach. Among the LTC strategies, reactivity controlled compression ignition (RCCI) strategy has a better combustion phasing control along with higher fuel conversion efficiency and lower NOx and soot emissions. The present study investigates the nano-particle emissions from RCCI engine fuelled with a port injection of gasoline/methanol and direct injection of diesel. A single cylinder, water-cooled, 625cc automotive diesel engine with development ECU (electronic control unit) was modified, and a separate port fuel (PF) injector is installed in the intake manifold to operate the engine in RCCI combustion mode.
Technical Paper

Split Injection Spray Development, Mixture Formation and Combustion Processes in Diesel Engine Piston Cavity: Spray Chamber Rig Test and Real Engine Performance Result

2018-09-10
2018-01-1698
The objectives of this study are to characterize the spray development, mixture formation and combustion processes in a 2-dimensional (2D) model piston cavity in a high pressure, high temperature constant volume vessel (CVV) rig test and to correlate the rig test results with real engine performance tests. In the rig test, the fuel was injected into the CVV by a single-hole piezo actuator nozzle under the various split injection strategies. The 2D model piston cavity of the same shape as that used in a small-more diesel engine was employed to form the impinging spray and flame. In order to observe the spray development and mixture formation processes, the tracer laser absorption scattering (LAS) technique was adopted. The spatial distributions of the vapor and liquid phases and the spray mixture formation characteristics in the 2D piston cavity were investigated. The spray combustion and soot formation processes were studied using a high-speed video camera.
Technical Paper

Improving Combustion and Emission Performance of Heavy-Duty Natural-Gas Engine using Inner-convex Piston with Enhanced Turbulence

2018-09-10
2018-01-1685
Compressed Natural Gas (CNG), because of its low cost, high H/C ratio, and high octane number, has great potential in automotive industry, especially for heavy-duty commercial vehicles. However, Relative slow flame speed of natural gas may lead to long combustion duration and low thermal efficiency. What's worse, it probably contributes to knock aggravating engine thermal load and reliability at high load. Enhancing the turbulence intensity in combustion chamber is an effective way to accelerate flame propagation speed and improve combustion performance. In this study, the flow simulations of the original piston bowl and several piston bowls with different inner-convex walls were carried out using three-dimensional computational fluid dynamics (3D-CFD) software CONVERGE. The numerical results show the piston bowls with inner-convexities could disturb the charge swirl motion and enhance turbulence of different intensity.
Technical Paper

Analyzing factors affecting gross indicated efficiency when inlet temperature is changed

2018-09-10
2018-01-1780
Observations from engine experiments indicates that the gross indicated efficiency (GIE) increases when the inlet temperature is lowered. The change in inlet temperature affects several important factors, such as the combustion profile (affecting exhaust losses), working fluid properties, combustion efficiency and heat transfer losses. These factors all individually contributes to the resulting change in GIE. However, due to their strong dependency to temperature it is not possible to quantify each parameters contribution. Therefore, a simulation model in GT-power has been created and calibrated to the engine experiments. With simulations the temperature dependency can be broken up and it becomes possible to evaluate each factors contribution to GIE. The simulation results indicate that the specific heats of the working medium is the largest contributor. Heat transfer and combustion efficiency also contributes but are not as significant as the effect from specific heats.
Technical Paper

Investigation into the Optimized Heat Release Rate and Corresponding Variation of In-cylinder Specific Heat Ratio for the Improvement in Thermal Efficiency by Two-Zone Combustion Model Analysis

2018-09-10
2018-01-1796
It has been demanded to increase in brake thermal efficiency (BTE) of any internal combustion engines for suppressing global warming and/or fossil energy exhaustion. Improvement in friction and pumping loss could be effective in short term, but should not be effective for further increase in BTE because of their very low contribution. Improvement in heat loss could be one of the important measures; however, all improved heat energy is not directly converted to the brake work. To increase in the heat conversion efficiency into indicated work, compression (or expansion) ratio and specific heat ratio are ideally important. Nevertheless, specific heat ratio is not emphasized so far, since it can’t be easily controlled. This study focused on the simulation of instantaneous specific heat ratio and local equivalence ratio which varied with heat release rate profile.
Technical Paper

Novel Rankine Cycle for Hybrid Vehicles

2018-09-10
2018-01-1711
The European Union (EU) has defined legally-binding targets for the fleet of new cars allowing 95 grams CO2 per kilometer in 2021. It is already under discussion to reduce average emissions of the EU car fleet by further 15 % in 2025 and again by 30 % in 2030 compared to 2021 goal. Therefore, improvement of fuel economy is becoming one of most important issues for the car manufacturers. Today’s conventional car powertrain systems are reaching their technical limits and will not be able to meet future fuel economy targets without further development of additional measures. This paper presents the analysis of a Rankine cycle unit applied to improve overall efficiency of a hybrid electric vehicle (HEV). The authors propose a new concept for recovering a considerable part of exhaust waste heat from a HEV with spark ignition internal combustion engine (ICE) by applying a bottoming Rankine cycle with a Ruths storage tank.
Technical Paper

Critical analysis of PM index and other fuel indices: Impact of gasoline fuel volatility and chemical composition

2018-09-10
2018-01-1741
Among the challenges facing the development of gasoline engines, one of the most important is the reduction of particles emissions. This study proposes a critical evaluation of the influence of fuel characteristics on gasoline particles emission. For this, a selected fuel matrix composed of 25 fuels was built presenting different volatility and chemical composition (content in total aromatics, heavy cuts and ethanol). To represent the fuel sooting tendency, seven Fuel Particle Indices were selected based on a literature review, namely, Particle Matter Index (PMI), PNI, Threshold Sooting index (TSI), Smoke point (SP), Oxygen Extended Sooting Index (OESI), T-index 1-2. These indices were evaluated on the fuel matrix on the basis of three main areas: First, the sensitivity to fuel variation. Second, the agreement with engine particles emissions measured on WLTC and NEDC homologation tests on two vehicles.
Technical Paper

Evaluating emissions in a modern compression ignition engine using multi-dimensional PDF-based stochastic simulations and statistical surrogate generation

2018-09-10
2018-01-1739
Digital engineering workflows, involving physico-chemical simulation and advanced statistical algorithms, offer a robust and cost-effective methodology for model-based internal combustion engine development. In this paper, a modern Tier 4 capable Cat® C4.4 engine is modelled using a digital workflow that combines the probability density function (PDF)-based Stochastic Reactor Model (SRM) Engine Suite with the statistical Model Development Suite (MoDS). In particular, an advanced multi-zonal approach is developed and applied to simulate fuels, in-cylinder combustion and gas phase as well as particulate emissions characteristics, validated against measurements and benchmarked with respect to the predictive power and computational costs of the baseline model. The multi-zonal SRM characterises the combustion chamber on the basis of different multi-dimensional PDFs dependent upon the bulk or the thermal boundary layer in contact with the cylinder liner.
Technical Paper

Monitoring Emission Performance of LPG vehicles by Remote Sensing Technique in Hong Kong

2018-09-10
2018-01-1820
Since 1st September 2014 the Hong Kong Environmental Protection Department (HKEPD) has been utilising Dual Remote Sensing technique to monitor the emissions from Gasoline and LPG vehicles for identifying high emitting vehicles running on road. Remote sensing measures and determines ratios of the emission gases of HC, CO and NO against CO2 which are used for determining if a vehicle is a high emitter. Characterisation of each emission gas is shown and its potential to identify a high emitter is established. The data covers a total of about 2,200,000 LPG vehicle emission measurements taken from 14 different remote sensing units. It was collected from 6th January 2012 to 20th April 2017 across a period before and after the launch of the Remote Sensing programme for evaluating the performance of the programme. The results show that the HKEPD Remote Sensing programme is very effective to detect high emitting vehicles and reduce on-road vehicle emissions.
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