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This paper presents engine performance and emissions of coconut oil-derived 10% biodiesel blends in petroleum diesel demonstrating simultaneous reduction of smoke and NOx emissions and increased brake power. The experiments were performed in a single-cylinder version of a light-duty diesel engine for three different fuels including a conventional diesel fuel and two B10 fuels of chemical-catalyst-based methyl-ester biodiesel (B10mc) and biological-catalyst-based ethyl-ester biodiesel (B10eb). The engine tests were conducted at fixed speed of 2000 rpm and injection pressure of 130 MPa. In addition to the fuel variation, the injection timing and rate of exhaust gas recirculation (EGR) were also varied because they impact the combustion and thus the efficiency and emissions significantly.

This study aims to clarify the spray development of ethanol, gasoline and iso-octane fuel, delivered by a multi-hole injector and spark-ignition direct-injection (SIDI) fuelling system. The focus is on how fuel properties impact temporal and spatial evolution of sprays at realistic ambient conditions. Two optical facilities were used: (1) a constant-flow spray chamber simulating cold-start conditions and (2) a single-cylinder SIDI engine running at normal, warmed-up operating conditions. In these optical facilities, high-speed Mie-scattering imaging is performed to measure penetrations of spray plumes at various injection pressures of 4, 7, 11 and 15 MPa. The results show that the effect of fuel type on the tip penetration length of the sprays depends on the injection conditions and the level of fuel jet atomisation and droplet breakup.

Soot particles emitted from modern diesel engines, despite significantly lower total mass, show higher reactivity and toxicity than black-smoking old engines, which cause serious health and environmental issues. Soot nanostructure, i.e. the internal structure of soot particles composed of nanoscale carbon fringes, can provide useful information to the investigation of the particle reactivity and its oxidation status. This study presents the nanostructure details of soot particles sampled directly from diesel flames in a working diesel engine as well as from exhaust gases to compare the internal structure of soot particles in the high formation stage and after in-cylinder oxidation. Thermophoretic soot sampling was conducted using an in-house-designed probe with a lacy transmission electron microscope (TEM) grid stored at the tip.

A 13 L HD diesel engine was converted to run as a flame propagation engine using the HEDGE™ Dual-Fuel concept. This concept consists of pre-mixed gasoline ignited by a small amount of diesel fuel - i.e., a diesel micropilot. Due to the large bore size and relatively high compression ratio for a pre-mixed combustion engine, high levels of cooled EGR were used to suppress knock and reduce the engine-out emissions of the oxides of nitrogen and particulates. Previous work had indicated that the boosting of high dilution engines challenges most modern turbocharging systems, so phase I of the project consisted of extensive simulation efforts to identify an EGR configuration that would allow for high levels of EGR flow along the lug curve while minimizing pumping losses and combustion instabilities from excessive backpressure. A potential solution that provided adequate BTE potential was consisted of dual loop EGR systems to simultaneously flow high pressure and low pressure loop EGR.

For internal combustion engines, the compression ratio (r) is defined as the ratio of volume at bottom dead center to the volume at top dead center and is a fundamental design parameter influencing the thermodynamic operation of the modern combustion engine. Thermodynamic cycle analysis can show that thermal efficiency increases as the compression ratio increases. An increase in the compression ratio changes the cycle such that peak compression pressure and temperatures are increased resulting in subsequent increases in the peak combustion pressure and temperature. Since the average temperature of heat addition is increased in the cycle, the thermal efficiency would theoretically increase as long as both cycles had the same heat rejection processes. These changes in peak pressure and temperature of the cycle must also be evaluated in terms of anticipated increases in engine friction and changes to the combustion duration respectively.

Simulations used to estimate carbon dioxide (CO2) emissions and fuel consumption of medium- and heavy-duty vehicles over prescribed drive cycles often employ engine fuel maps consisting of engine measurements at numerous steady-state operating conditions. However, simulating the engine in this way has limitations as engine controls become more complex, particularly when attempting to use steady-state measurements to represent transient operation. This paper explores an alternative approach to vehicle simulation that uses a “cycle average” engine map rather than a steady state engine fuel map. The map contains engine CO2 values measured on an engine dynamometer on cycles derived from vehicle drive cycles for a range of generic vehicles. A similar cycle average mapping approach is developed for a powertrain (engine and transmission) in order to show the specific CO2 improvements due to powertrain optimization that would not be recognized in other approaches.

Motorcycle usage continues to expand globally. Motorcycles use various fuels in different countries and regions, and it is required that they comply with emissions and fuel consumption regulations as specified in UN-GTR No.2 (WMTC). In general, a motorcycle engine has a large bore diameter and a high compression ratio due to demands of high performance. Poor fuel quality may cause damage to the engine, mainly by knocking. Knock control systems utilizing high-frequency vibration detection strategies like knock sensors, which are equipped on several sport-touring motorcycles, are not used widely for reasons of complex construction and high cost. This research aims to develop a new concept of combustion control for common motorcycle as an alternative.

The importance of radiative heat transfer on the combustion and soot formation characteristics under nominal ECN Spray A conditions has been studied numerically. The liquid n-dodecane fuel is injected with 1500 bar fuel pressure into the constant volume chamber at different ambient conditions. Radiation from both gas-phase as well as soot particles has been included and assumed as gray. Three different solvers for the radiative transfer equation have been employed: the discrete ordinate method, the spherical-harmonics method and the optically thin assumption. The radiation models have been coupled with the transported probability density function method for turbulent reactive flows and soot, where unresolved turbulent fluctuations in temperature and composition are included and therefore capturing turbulence-chemistry-soot-radiation interactions. Results show that the gas-phase (mostly CO2 ad H2O species) has a higher contribution to the net radiation heat transfer compared to soot.

The Drive By Wire (hereafter referred to as DBW) system is the electronically throttle control system. It controls a throttle valve in order to aim at a suitable throttle position according to an engine operating condition and a demand of driver or rider. This system is basically composed of a throttle body with driving motor, an Accelerator Position Sensor (hereafter referred to as APS), and an Electronic Control Unit (hereafter referred to as ECU). The DBW system is spreading to motorcycle field as replacement of existing mechanical intake control system. This is because there are some advantages as the following especially in the large displacement model: capability for installation of several functions, flexibility in adaptation to recent environmental regulations, and effect on reduction of system cost, etc. In general, the motorcycle has some unique features compared with the automobile. Among them, important features for the DBW system are following three points.

Low temperature combustion through in-cylinder blending of fuels with different reactivity offers the potential to improve engine efficiency while yielding low engine-out NOx and soot emissions. A Navistar MaxxForce 13 heavy-duty compression ignition engine was modified to run with two separate fuel systems, aiming to utilize fuel reactivity to demonstrate a technical path towards high engine efficiency. The dual-fuel engine has a geometric compression ratio of 14 and uses sequential, multi-port-injection of a low reactivity fuel in combination with in-cylinder direct injection of diesel. Through control of in-cylinder charge reactivity and reactivity stratification, the engine combustion process can be tailored towards high efficiency and low engine-out emissions. Engine testing was conducted at 1200 rpm over a load sweep.

Ethanol has been selected as a fuel for gasoline compression ignition (GCI) engines realising partially premixed charge combustion, considering its higher resistance to auto-ignition, higher evaporative cooling and oxygen contents than widely used gasoline, all of which could further improve already high efficiency and low smoke/NOx emissions of GCI engines. The in-cylinder phenomena and engine-out emissions were measured in a single-cylinder automotive-size common-rail diesel engine with a special emphasis on double injection strategies implementing early first injection near BDC and late second injection near TDC.

This paper talks about using an approach to simulate snow mass falling from roof of cab on the cowl tray of a commercial truck and predicting the durability life of the cowl tray based on this loading. It has always been a challenge for analysts to model the behavior of snow/slurry in dynamic simulations especially where the area of concern is structure and not the fluid. The conventional approach followed in most industries would be either to model snow as soft rubber or to divert from the conventional Lagrangian algorithm for mesh movement towards Eulerian method (or ALE algorithm). Although modeling snow as soft rubber captures the basic physics of the problem, it is not able to correctly simulate the fluid structure interaction behavior and the pressure wave movement inside the snow/slurry when it comes in contact with the structure.

The effects of different blends of Soybean Methyl Ester (biodiesel) and ultra low sulfur diesel (ULSD) fuel: B-00 (ULSD), B-20, B-40, B-60, B-80 and B-100 (biodiesel); on autoignition, combustion, performance, and engine out emissions of different species including particulate matter (PM) in the exhaust, were investigated in a single-cylinder, high speed direct injection (HSDI) diesel engine equipped with a common rail injection system. The engine was operated at 1500 rpm under simulated turbocharged conditions at 5 bar IMEP load with varied injection pressures at a medium swirl of 3.77 w ithout EGR. Analysis of test results was done to determine the role of biodiesel percentage in the fuel blend on the basic thermodynamic and combustion processes under fuel injection pressures ranging from 600 bar to 1200 bar.

Influence of the injection pressure on the temporal evolution of lifted jet flame base upon the bowl wall impingement has been studied in a small-bore optical diesel engine. Previous studies suggest that the jet-wall interaction causes re-entrainment of combustion products into the incoming jet, which shortens the lift-off length during the injection and thereby increasing downstream soot. After the end of injection, the flame base slowly moves downstream as the diminishing jet momentum results in reduced re-entrainment. How the injection pressure impacts this transient behaviour of the flame base is a main focus of the present study. Common-rail pressure was varied from 70 to 160 MPa at a fixed injection mass (10 mg per hole) and timing (7°CA bTDC).

The effect of engine coolant and oil temperature on the performance was experimentally evaluated on a Navistar 12.4 Liter engine. The engine speed and load selected for evaluation represented the engine conditions typically found during a Class-8 truck’s cruising operation. In order to study the effect of oil and coolant temperature in isolation, the production coolant-cooled oil-cooler was replaced with a separate oil and coolant conditioning system. The piston and liner surface temperature was also logged at select locations to provide solid temperature response to coolant and oil temperature changes. The engine tests showed that oil temperature variation had greater impact on the engine performance compared to the coolant temperature. This performance improvement came primarily from the lower combustion heat rejection and reduced friction at moderate engine loads. At higher engine loads the performance improvement was largely due to lowered heat rejection.

This paper investigates the effects of variable valve actuation on combustion in a Diesel engine. Early inlet valve closing (EIVC) lowered the pressure and temperature during the compression stroke, resulting in a longer ignition delay as the fuel mixed more homogenously with the charge air ahead of combustion. Combustion was characterized by prominent cool flame chemistry and a faster, more energetic, premixed combustion. Tests were performed on a 6.4L V8 engine at loads up to 5 bar BMEP. The use of EIVC showed significant reductions of soot (above 90%) and fuel efficiency improvements (of 5%) with NOx levels below the US 2010 standard of 0.2g/bhp-hr. The improvements in emissions and fuel economy came from controlling in-cylinder temperatures and optimizing combustion phasing. For a constant engine-out NOx emission, EIVC improved fuel economy as the amount of EGR and the engine back pressure requirement were reduced.

The performance of Gasoline Direct Injection (GDI) engines is governed by multiple physical processes such as the internal nozzle flow and the mixing of the liquid stream with the gaseous ambient environment. A detailed knowledge of these processes even for complex injectors is very important for improving the design and performance of combustion engines all the way to pollutant formation and emissions. However, many processes are still not completely understood, which is partly caused by their restricted experimental accessibility. Thus, high-fidelity simulations can be helpful to obtain further understanding of GDI injectors. In this work, advanced simulation and experimental methods are combined in order to study the spray characteristics of two different 3-hole GDI injectors.

Diesel engine manufacturers have faced stringent emission regulations for oxides of nitrogen and particulate emissions for the last two decades. The emission challenges have been met with a host of technologies such as turbocharging, exhaust gas recirculation, high- pressure common rail fuel injection systems, diesel aftertreatment devices, and electronic engine controls. The next challenge for diesel engine manufacturers is fuel-economy regulations starting in 2014. As a prelude to this effort the department of energy (DOE) has funded the Supertruck project which intends to demonstrate 50% brake-thermal efficiency on the dynamometer while meeting US 2010 emission norms. In order to simultaneously meet the emission and engine efficiency goals in the cost effective manner engine manufacturer have adopted a systems approach, since individual fuel saving technologies can actually work against each other if fuel economy is not approached from a total vehicle perspective.

This study applies high-speed particle image velocimetry (HS-PIV) and flame image velocimetry (HS-FIV) to show flow fields under the effect of varied swirl ratios in a small-bore optical compression-ignition engine. The base swirl ratio and maximum swirl ratio conditions were applied to investigate structures, magnitude and turbulence distribution of the in-cylinder flow as well as the flow within the flame. For each swirl ratio, 100 individual cycles were measured for PIV analysis at motoring conditions and then another 100 cycles for FIV analysis at firing conditions. The derived flow fields were ensemble averaged to show flow structure evolution while the spatial filtering method was applied to extract high-frequency flow component for the analysis of turbulence distributions. The results showed that the intake air flow generates undefined, chaotic flow fields, which are followed by a gradual production of an asymmetric swirl flow.

The present study focuses on the observation of knock phenomena in a small-bore optical diesel engine. Current understanding is that a drastic increase of pressure during the premixed burn phase of the diesel combustion causes gas cavity resonances, which in turn induce a high frequency pressure ringing. The frequency and severity of this ringing can be easily measured by using a pressure transducer. However, visual information of flames under knocking conditions is limited especially for a small-bore diesel engine. To fill this gap, high-speed imaging of soot luminosity is performed in conjunction with in-cylinder pressure measurement during knocking cycles in an automotive-size optical diesel engine. From the experiments, flames were observed to oscillate against the direction of the swirl flow when the pressure ringing occurred.