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Electronic controls in internal combustion engines require an in-cylinder combustion sensor to produce a feedback signal to the ECU (Engine Control Unit). Recent research indicated that the ion current sensor has many advantages over the pressure transducer, related mainly to lower cost. Modified glow plugs in diesel engines, and fuel injectors in both gasoline and diesel engines can be utilized as ion current sensors without the addition any part or drilling holes in the cylinder head needed for the pressure transducer. Multi sensing fuel injector (MSFI) system is a new technique which instruments the fuel injector with an electric circuit to perform multiple sensing tasks including functioning as an ion sensor in addition to its primary task of delivering the fuel into the cylinder. It is necessary to fundamentally understand MSFI system.

Many approaches have been taken to determine the burning velocity in internal combustion engines. Experimentally, the burning velocity has been determined in optically accessible gasoline engines by tracking the propagation of the flame front from the spark plug to the end of the combustion chamber. These experiments are costly as they require special imaging techniques and major modifications in the engine structure. Another approach to determine the burning velocity is from 3D CFD simulation models. These models require basic information about the mechanisms of combustion which are not available for distillate fuels in addition to many assumptions that have to be made to determine the burning velocity. Such models take long periods of computational time for execution and have to be calibrated and validated through experimentation.

Emissions of Unburned Hydrocarbons (UHC) from diesel engines are a particular concern during the starting process, when after-treatment devices are typically below optimal operating temperatures. Drivability in the subsequent warm-up phase is also impaired by large cyclic fluctuations in mean effective pressure (MEP). This paper discusses in-cylinder wall temperature influence on unburned hydrocarbon emissions and combustion stability during the starting and warm-up process in an optical engine. A laser-induced phosphorescence technique is used for quantitative measurements of in-cylinder wall temperatures just prior to start of injection (SOI), which are correlated to engine out UHC emission mole fractions and combustion phasing during starting sequences over a range of charge densities, at a fixed fueling rate. Squish zone cylinder wall temperature shows significant influence on engine out UHC emissions during the warm-up process.

On-board fuel identification is important to ensure engine safe operation, similar power output, fuel economy and emissions levels when different fuels are used. Real-time detection of physical and chemical properties of the fuel requires the development of identifying techniques based on a simple, non-intrusive sensor. The measured crankshaft speed signal is already available on series engine and can be utilized to estimate at least one of the essential combustion parameters such as peak pressure and its location, rate of cylinder pressure rise and start of combustion, which are an indicative of the ignition properties of the fuel. Using a dynamic model of the crankshaft numerous methods have been previously developed to identify the fuel type but all with limited applications in terms of number of cylinders and computational resources for real time control.

Surrogates for JP-8 have been developed in the high temperature gas phase environment of gas turbines. In diesel engines, the fuel is introduced in the liquid phase where volatility plays a major role in the formation of the combustible mixture and autoignition reactions that occur at relatively lower temperatures. In this paper, the role of volatility on the combustion of JP-8 and five different surrogate fuels was investigated in the constant volume combustion chamber of the Ignition Quality Tester (IQT). IQT is used to determine the derived cetane number (DCN) of diesel engine fuels according to ASTM D6890. The surrogate fuels were formulated such that their DCNs matched that of JP-8, but with different volatilities. Tests were conducted to investigate the effect of volatility on the autoignition and combustion characteristics of the surrogates using a detailed analysis of the rate of heat release immediately after the start of injection.

The need for using alternative fuel sources continues to grow as industry looks towards enhancing energy security and lowering emissions levels. In order to capture the potential of these megatrends, this study focuses on the relationship between ignition energy, thermal efficiency, and combustion stability of a 0.5 L single cylinder engine powered by compressed natural gas (CNG) at steady state operation. The goal of the experiment was to increase ignition energy at fixed lambda values to look for gains in thermal efficiency. Secondly, a lambda sweep was performed with criteria of maintaining a 4% COVIMEP by increasing the ignition energy until an appropriate threshold for stable combustion was found. The engine performance was measured with a combustion analysis system (CAS), to understand the effects of thermal efficiency and combustion stability (COVIMEP). Emissions of the engine were measured with an FTIR.

Advanced injection systems play a major role in reducing engine out emission in modern diesel engines. One interesting technology is the common rail injection system which is becoming more vital in controlling emission due to its flexibility in injection pressure, timing and number of injection events. Many studies have showed the advantages of using such injection parameters to meet the strict emission and improve engine performance. A glow plug/ ion current sensor was used to measure ionization produced during the combustion process. The ion current signal contains many valuable information including combustion phasing, duration and combustion resonance. In prior publications, it was demonstrated the capability of the ion current to control the combustion phasing and the ability to detect combustion resonance. Therefore, the experimental testing was conducted under controlled combustion phasing using the feedback from the ion current sensor.

This paper presents experimental study on the impact of using fuels with different physical and chemical properties in a diesel engine. Research is driven towards finding an alternative or extender to the conventional diesel fuel for compression ignition engines. Such alternative fuels have wide ranges of physical and chemical properties which are not suitable for CI engines. Advanced injection systems and control strategies in modern diesel engines permit operation to be extended to a wider range of fuels. Therefore, experimental investigation to understand the effects of different fuels on engine performance, combustion, and emissions are necessary. The study covers the effect of using different fuels such as JP-8 and Sasol-IPK on a modern automotive diesel engine. The engine used in this study is a 2.0L, 4 cylinders, direct injection diesel engine fitted with piezo-driven injectors.

Natural gas has been considered to be one of the most promising alternative fuels due to its lower NOx and soot emissions, less carbon footprint as well as attractive price. Furthermore, higher octane number makes it suitable for high compression ratio application compared with other gaseous fuels. For better economical and lower emissions, a turbocharged, four strokes, direct injection, high pressure common rail diesel engine has been converted into a diesel/natural gas dual-fuel engine. For dual-fuel engine operation, natural gas as the main fuel is sequentially injected into intake manifold, and a very small amount of diesel is directly injected into cylinder as the ignition source. In this paper, a dual-fuel electronic control unit (ECU) based on the PowerPC 32-bit microprocessor was developed. It cooperates with the original diesel ECU to control the fuel injection of the diesel/natural gas dual-fuel engine.

Advanced valvetrain coupled with Direct Injection (DI) provides an opportunity to simultaneous reduction of fuel consumption and emissions. Because of their robustness and cost performance, multi-hole injectors are being adopted as gasoline DI fuel injectors. Ethanol and ethanol-gasoline blends synergistically improve the performance of a turbo-charged DI gasoline engine, especially in down-sized, down-sped and variable-valvetrain engine architecture. This paper presents Mie-scattering spray imaging results taken with an Optical Accessible Engine (OAE). OAE offers dynamic and realistic in-cylinder charge motion with direct imaging capability, and the interaction with the ethanol spray with the intake air is studied. Two types of cams which are designed for Early Intake Valve Close (EIVC) and Later Intake Valve Close (LIVC) are tested, and the effect of variable valve profile and deactivation of one of the intake valves are discussed.

Internal combustion engine control requires feedback signals to the ECU in order to meet the increasingly stringent emissions standards. Reducing the number of on-board sensors needed for proper engine performance would reduce the cost and complexity of the electronic system. This paper presents a new technique to enable one engine element, the fuel injector, to perform multiple sensing tasks in addition to its primary task of delivering the fuel into the cylinder. The injector is instrumented within an electric circuit to produce a signal indicative of the ionization produced from the combustion process in electronically controlled diesel engines. The output of the multi sensing fuel injector (MSFI) system can be used as a feedback signal to the engine control unit (ECU) for injection timing and diagnostics of the injection and combustion processes.

The use of biodiesel and its blends with ultra low sulfur diesel (ULSD) is gaining significant importance due to its ability to burn in conventional diesel engines with minor modifications. However the chemical and physical properties of biodiesel are different compared to the conventional ULSD. These differences directly impact the injection, spray formation, auto ignition and combustion processes which in turn affect the engine-out emissions. To understand the effect of fueling with B-20, tests were conducted on a single cylinder 0.42L direct injection research diesel engine. The engine is equipped with a common rail injection system, variable EGR and swirl control systems and was operated at a constant engine speed of 1500 rpm and 3 bar IMEP to simulated turbocharged conditions. Injection timing and duration were adjusted with B-20 at different locations of peak premixed combustions (LPPC) and two different swirl ratios to achieve 3 bar IMEP.

Because of their robustness and cost performance, multi-hole gasoline injectors are being adopted as the direct injection (DI) fuel injector of choice as vehicle manufacturers look for ways to reduce fuel consumption without sacrificing power and emission performance. To realize the full benefits of direct injection, the resulting spray needs to be well targeted, atomized, and appropriately mixed with charge air for the desirable fuel vapor concentration distributions in the combustion chamber. Ethanol and ethanol-gasoline blends synergistically improve the turbo-charged DI gasoline performance, especially in down-sized, down-sped and variable-valve-train engine architecture. This paper presents the spray imaging results from two multi-hole DI gasoline injectors with different design, fueled with pure ethanol (E100) or gasoline (E0), under homogeneous and stratified-charge conditions that represent typical engine operating points.

Operation of flex fuel vehicles requires operation with a range of fuel properties. The significant differences in the heat of vaporization and energy density of E0-E100 fuels and the effect on spray development need to be fully comprehended when developing engine control strategies. Limited enthalpy for fuel vaporization needs to be accounted for when developing injection strategies for cold start, homogeneous and stratified operation. Spray imaging of multi-hole gasoline injectors with fuels ranging from E0 to E100 and environmental conditions that represent engine operating points from ambient cold start to hot conditions was performed in a spray chamber. Schlieren visualization technique was used to characterize the sprays and the results were compared with Laser Mie scattering and Back-lighting technique. Open chamber experiments were utilized to provide input and validation of a CFD model.

Ion current sensors have been considered for the feedback electronic control of gasoline and diesel engines and for onboard vehicles powered by both engines, while operating on their conventional cycles or on the HCCI mode. The characteristics of the ion current signal depend on the progression of the combustion process and the properties of the combustion products in each engine. There are large differences in the properties of the combustible mixture, ignition process and combustion in both engines, when they operate on their conventional cycles. In SI engines, the charge is homogeneous with an equivalence ratio close to unity, ignition is initiated by an electric spark and combustion is through a flame propagating from the spark plug into the rest of the charge.

The effect of biodiesel on the Particulate emissions is gaining significant attention particularly with the drive for the use of alternative fuels. The particulate matter (PM), especially having a diameter less than 50 nm called the Nanoparticles or Nucleation mode particles (NMPs), has been raising concerns about its effect on human health. To better understand the effect of biodiesel and its blends on particulate emissions, steady state tests were conducted on a small-bore single-cylinder high-speed direct-injection research diesel engine. The engine was fueled with Ultra-Low Sulfur Diesel (ULSD or B-00), a blend of 20% soy-derived biodiesel and 80% ULSD on volumetric basis (B-20), B-40, B-60, B-80 and 100% soy-derived biodiesel (B-100), equipped with a common rail injection system, EGR and swirl control systems at a load of 5 bar IMEP and constant engine speed of 1500 rpm.

The current study focused on the effects B20 fuel (20% soybean-based biodiesel) and SCR entrance shapes on a light-duty, high-speed, 2.8L common-rail 4-cylinder diesel engine, at different exhaust temperatures. The results indicate that B20 has less deNOX efficiency at low temperature than ULSD, and that N₂O emission need to be characterized as well as NH₃ slip. If a mixer and enough mixing length are used, longer divergence section does not improve the deNOX efficiency significantly under the speed ranges tested.

Biodiesel offers a potentially viable alternative fuel source for diesel automotive applications. However, biodiesel may present problems at colder temperatures due to the crystallization of fatty acid methyl esters and precipitation of other components, such as unreacted triglycerides and sterol glycosides in biodiesel. At lower temperatures, the fuel gels until it solidifies in the fuel lines, clogging the fuel filter, and shutting down the engine. A laboratory-based continuous loop fuel system was utilized to determine the flow properties at low temperatures of biodiesel in B100, B20, and B10 blends for soybean and choice white grease (pig fat) biodiesel fuel. The continuous loop fuel delivery system was designed to be similar to those that can be found in engines and vehicles currently in use, and provided a mechanical pump or an electric pump as a means to simulate systems found in the different types of vehicles.

The feasibility of using ultra low sulfur diesel (ULSD), synthetic paraffinic kerosene (S-8), military grade jet fuel (JP-8) and commercial B20 blend (20% v biodiesel in ULSD) in a power generator equipped with a compression ignition (CI) engine was investigated according to the MIL-STD-705C military specifications for engine-driven generator sets. Several properties of these fuels such as cetane number, lubricity, viscosity, cold flow properties, heat of combustion, distillation temperatures, and flash point, were evaluated. All fuels were tested for 240 hours at a stationary load of 30 kW (60% of full load) with no alteration to the engine calibrations. The brake specific fuel consumption (BSFC), brake thermal efficiency (BTE), frequency, and power of the generator using S-8, JP-8 and B20 were compared with the baseline fuel ULSD.

An experimental investigation was conducted on a small-bore, high-speed diesel engine to study the effect of different operating parameters on combustion and engine-out emissions in the conventional and low temperature regimes. For the conventional diesel combustion, the spray behavior is analyzed and a differentiation is made between the conditions in the small-bore and the larger bore quiescent chamber engines. The effects of the injection pressure, exhaust gas recirculation (EGR), injection timing and swirl ratio (SR) on combustion and engine-out emission are investigated. The trade-off between NOx and smoke, measured in Bosch smoke unit, (BSU), is investigated with a special attention to the low temperature combustion regime, (LTC). The results showed that the LTC regime could be reached at fairly high EGR rates under all the injection pressures investigated in this work. The margin for the variation in EGR was limited just before the misfiring EGR.