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Increasing interest in biofuels—specifically, biodiesel as a pathway to energy diversity and security—have necessitated the need for research on the performance and utilization of these fuels and fuel blends in current and future vehicle fleets. One critical research area is related to achieving a full understanding of the impact of biodiesel fuel blends on advanced emission control systems. In addition, the use of biodiesel fuel blends can degrade diesel engine oil performance and impact the oil drain interval requirements. There is limited information related to the impact of biodiesel fuel blends on oil dilution. This paper assesses the oil dilution impacts on an engine operating in conjunction with a diesel particle filter (DPF), oxides of nitrogen (NOx) storage, a selective catalytic reduction (SCR) emission control system, and a 20% biodiesel (soy-derived) fuel blend.

This paper describes the set-up and testing of a single cylinder 25cc, air cooled, 4-stroke Spark Ignition (SI) engine converted to run in Homogeneous Charge Compression Ignition (HCCI) mode with the aid of various combustion control systems. The combustion control systems were investigated regarding their effects on combustion stability and heat release phasing. Engine operation was compared with unique findings from previous work done on a very small 2-stroke HCCI engine. HCCI engine operation was possible between 1000 - 4000 rpm when using Diethyl Ether (DEE) as the test fuel. Maximum operational fuel-air equivalence ratio (Φ) was 0.75 when operating without Exhaust Gas Recirculation (EGR). This relatively high equivalence ratio was attainable due to thermal gradients induced by the high surface area to volume ratio of the small engine combustion chamber, resulting in high chamber heat transfer.

Controlled Autoignition (CAI) is a very promising technology for simultaneous reduction of fuel consumption and engine-out emissions [3, 4, 9, 16]. But the operating range of this combustion mode is limited on the one hand by high pressure gradients with the subsequent occurrence of knocking, increasing NOX-emissions and cyclic variations, and on the other hand by limited operating stability due to low mixture temperatures. At higher loads the required amount of internal EGR decrease to reach self-ignition conditions decrease and hence the influence of the ignition spark gain. The timing of the ignition spark highly influence the combustion process at higher loads. With the ignition spark, pre-reactions are initialized with a defined heat release. Thus the location of inflammation and flame propagation can be strongly influenced and cyclic variations at higher loads can be reduced.

The heavy duty Particle Measurement Programme (PMP) inter-laboratory exercise consists of three parts: 1) the exploratory work to refine the measurement protocol, 2) the validation exercise where each lab will measure the emissions of a “golden” engine with two “golden” particle number systems simultaneously sampling from full and partial flow dilution systems, and 3) the round-robin where the emissions of a “reference” engine will be determined with a lab’s own particle number instrumentation. This paper presents the results of the exploratory work and describes the final protocol for testing in the validation exercise (and round robin) along with the necessary facility modifications required for compliance with the protocol. Key aspects of the protocol (e.g. filter material, flow rates at the full and partial flow systems, the pre-conditioning etc.) are explained and justified.

The continual reduction of diesel engine heavy-duty nitrous oxides and particulate matter emissions due to Environmental Protection Agency (EPA) regulations has resulted in significant changes to engine hardware since 1998. Such changes have included use of cooled exhaust gas recirculation, clean gas induction, oxidation catalysts, variable geometry turbochargers, lean nitrous oxide traps, urea selective catalytic reduction, passive and catalyzed particulate matter filters, and engine design changes to reduce oil consumption while allowing use of low sulfur diesel fuel (DF-2) and maintaining oil change intervals and subsystem durability levels of previous model years. The net result from a propulsion system perspective is increased heat rejection, additional induction and exhaust system volume, increased system weight, and less tolerance to military fuels and lubricants.

This paper investigates the performance, combustion characteristics, and emissions of a small single cylinder DI diesel engine with biodiesel fuel (BDF) derived from unused rape, soybean, and palm oils. Compared with ordinary gas oil, the BDFs showed similar brake thermal efficiencies, better ignitability, and considerably reduced smoke densities, while the NOx emissions were somewhat higher. The injection characteristics and engine performance were also examined using neat Methyl Oleate (OME) and OME-Methyl Palmitate (PME) blends. Basic experiments of suspended single droplets were performed to evaluate the differences in ignition, combustion, and soot formation characteristics of these fuels. The results showed shorter ignition lags and combustion durations for the OME droplets blended with PME and the soot formation rate with OME is about 13% that of gas oil droplets.

Ion sensors have been shown to be a low-cost and robust method of measuring start of combustion (SOC) in Homogeneous Charge Compression Ignition (HCCI) engines. The combustion event in an HCCI engine is governed by temperature sensitive chemical-kinetics and is highly fuel dependent. Autoignition variability between various fuels can also affect emissions, efficiency, and overall operating range of the HCCI engine. Ion sensors (i.e. modified spark-plugs) can be used pragmatically to detect the combustion event for various fuels in HCCI engines over a wide range of operating conditions. An investigation of the ion currents produced from the combustion of gasoline, ethanol, and n-heptane in a 1.9L 4-cylinder VW TDI diesel engine (converted to run in HCCI mode) is conducted over a range of equivalence ratios, intake temperatures, and intake pressures. Gasoline, ethanol and n-heptane have diverse autoignition characteristics which affect the overall operation of the HCCI engine.

Recent developments on highly downsized spark ignition engines have been focused on knocking behaviour improvement and the most advanced technologies combination can face up to 2.5 MPa IMEP while maintaining acceptable fuel consumption. Unfortunately, knocking is not the only limit that strongly downsized engines have to confront. The improvement of low-end torque is limited by another abnormal combustion which appears as a random pre-ignition. This violent phenomenon which emits a sharp metallic noise is unacceptable even on modern supercharged gasoline engines because of the great pressure rise that it causes in the cylinder (up to 20 MPa). The phases of this abnormal combustion have been analysed and a global mechanism has been identified consisting of a local ignition before the spark, followed by a propagating phase and ended by a massive auto-ignition. This last step finally causes a steep pressure rise and pressure oscillations.

The objective of this study was to examine the operating characteristics of a light duty multi cylinder compression ignition engine with regular gasoline fuel at low engine speed and load. The effects of fuel stratification by means of multiple injections as well as the sensitivity of auto-ignition and burn rate to intake pressure and temperature are presented. The measurements used in this study included gaseous emissions, filter smoke opacity and in-cylinder indicated information. It was found that stable, low emission operation was possible with raised intake manifold pressure and temperature, and that fuel stratification can lead to an increase in stability and a reduced reliance on increased temperature and pressure. It was also found that the auto-ignition delay sensitivity of gasoline to intake temperature and pressure was low within the operating window considered in this study.

In this work, heat loss was investigated in two different HCCI single cylinder engines. Thermocouples were adapted to the surfaces of the cylinder heads and the temperature oscillations were detected in a wide range of the engine operation conditions. The local heat transfer is analyzed with port fuel and direct injection, for different engine parameters and operating points. It is shown that the spatially averaged measured heat loss in HCCI operation represents the global heat loss well. The spatial variations are small in the operation map presuming stable operating points with low cyclic variations and good engine performance. Furthermore, the heat loss measured in HCCI operation is compared to the heat loss detected in homogeneous and stratified DI-SI operation in the same engine. It is shown that the local heat losses in stratified DI-SI operation show large variations, depending on the direction of the flame propagation.

It is generally accepted that emissions of nitrogen oxides (NOx) increase as the volume fraction of bio diesel increases in blends with conventional diesel fuel. While many mechanisms based on bio diesel effects on in-cylinder processes have been proposed to explain this observation, a clear understanding of the relative importance of each has remained elusive. To gain further insight into the cause(s) of the bio diesel NOx increase, experiments were conducted in a single-cylinder version of a heavy-duty diesel engine with extensive optical access to the combustion chamber. The engine was operated using two bio diesel fuels and two hydrocarbon reference fuels, over a wide range of loads, and using undiluted air as well as air diluted with simulated exhaust gas recirculation.

A prior study (Chon and Heywood, [1]) examined how the design and performance of spark-ignition engines evolved in the United States during the 1980s and 1990s. This paper carries out a similar analysis of trends in basic engine design and performance characteristics over the past decade. Available databases on engine specifications in the U.S., Europe, and Japan were used as the sources of information. Parameters analyzed were maximum torque, power, and speed; number of cylinders and engine configuration, cylinder displacement, bore, stroke, compression ratio; valvetrain configuration, number of valves and their control; port or direct fuel injection; naturally-aspirated or turbocharged engine concepts; spark-ignition and diesel engines. Design features are correlated with these engine’s performance parameters, normalized by engine and cylinder displacement.

Direct Injection (DI) is believed to be one of the key strategies for maximizing the thermal efficiency of Spark Ignition (SI) engines and meet the ever-tightening emissions regulations. This paper explores the use of Liquefied Petroleum Gas (LPG) liquid phase fuel in a 1.5 liter SI four cylinder gasoline engine with double over head camshafts, four valves per cylinder, and centrally located DI injector. The DI injector is a high pressure, fast actuating injector enabling precise multiple injections of the finely atomized fuel sprays. With DI technology, the injection timing can be set to avoid fuel bypassing the engine during valve overlap into the exhaust system prior to combustion. The fuel vaporization associated with DI reduces combustion chamber and charge temperatures, thereby reducing the tendency for knocking. Fuel atomization quality supports an efficient combustion process.

The authors present the supervisory control of a parallel hybrid powertrain, focusing on several issues related to the real-time implementation of optimal control based techniques, such as the Equivalent Consumption Minimization Strategies (ECMS). Real-time implementation is introduced as an intermediate step of a complete chain of tools aimed at investigating the supervisory control problem. These tools comprise an offline optimizer based on Pontryagin Minimum Principle (PMP), a two-layer real-time control structure, and a modular engine-in-the-loop test bench. Control results are presented for a regulatory drive cycle with the aim of illustrating the benefits of optimal control in terms of fuel economy, the role of the optimization constraints dictated by drivability requirements, and the effectiveness of the feedback rule proposed for the adaptation of the equivalence factor (Lagrange multiplier).

The volatile organic compounds (VOC) from diesel engines, including formaldehyde and benzene, are concerned and remain as unregulated harmful substances. The substances are positively correlated with THC emissions, but the VOC and aldehyde compounds at light load or idling conditions are more significant than THC. When coolant temperatures are low at light loads, there are notable increases in formaldehyde and acetaldehyde, and with lower coolant temperatures the increase in aldehydes is more significant than the increase in THC. When using ultra high EGR so that the intake oxygen content decreases below 10%, formaldehyde, acetaldehyde, benzene, and 1,3-butadiene increase significantly while smokeless and ultra low Nox combustion is possible.

Diesel engine ash emissions are composed of the non-combustible portions of diesel particulate matter derived mainly from lube oil, and over time can degrade diesel particulate filter performance. This paper presents results from a high temperature oxidation method (HTOM) used to estimate ash emissions, and engine oil consumption in real-time. Atomized lubrication oil and diesel engine exhaust were used to evaluate the HTOM performance. Atomized fresh and used lube oil experiments showed that the HTOM reached stable particle size distributions and concentrations at temperatures above 700°C. The HTOM produced very similar number and volume weighted particle size distributions for both types of lube oils. The particle number size distribution was unimodal, with a geometric mean diameter of about 23 nm. The volume size distribution had a geometric volume mean diameter of about 65 nm.

Hydrogen has been largely proposed as a possible alternative fuel for internal combustion engines. Its wide flammability range allows higher engine efficiency with leaner operation than conventional fuels, for both reduced toxic emissions and no CO2 gases. Independently, Homogenous Charge Compression Ignition (HCCI) also allows higher thermal efficiency and lower fuel consumption with reduced NOX emissions when compared to Spark-Ignition (SI) engine operation. For HCCI combustion, a mixture of air and fuel is supplied to the cylinder and autoignition occurs from compression; engine is operated throttle-less and load is controlled by the quality of the mixture, avoiding the large fluid-dynamic losses in the intake manifold of SI engines. HCCI can be induced and controlled by varying the mixture temperature, either by Exhaust Gas Recirculation (EGR) or intake air pre-heating.

Hydrogen is widely considered a promising fuel for future transportation applications for both, internal combustion engines and fuel cells. Due to their advanced stage of development and immediate availability hydrogen combustion engines could act as a bridging technology towards a wide-spread hydrogen infrastructure. Although fuel cell vehicles are expected to surpass hydrogen combustion engine vehicles in terms of efficiency, the difference in efficiency might not be as significant as widely anticipated [1]. Hydrogen combustion engines have been shown capable of achieving efficiencies of up to 45 % [2]. One of the remaining challenges is the reduction of nitric oxide emissions while achieving peak engine efficiencies. This paper summarizes research work performed on a single-cylinder hydrogen direct injection engine at Argonne National Laboratory.

The paper presents an experimental procedure for comparing different families of IC Engine lubricating pumps in terms of total consumed energy in a NEDC driving cycle. Measures are performed on a test rig able to reproduce the oil temperature profile, the lubrication circuit permeability and its variation during the engine warm-up. The pump under test is driven by a variable speed electric motor supplying the engine velocity profile of the driving cycle. The load on the pump is generated by means of a variable restrictor controlled in a closed loop by a proper combination of speed, temperature, flow rate and pressure signals in order to replicate the typical permeability of the lubricating circuit.

The introduction of CO₂-reduction technologies like Start-Stop or the Hybrid-Powertrain and the future emission legislation require a detailed optimization of the engine start-up. The combustion concept development as well as the calibration of the ECU makes an explicit thermodynamic analysis of the combustion process during the start-up necessary. Initially, the well-known thermodynamic analysis of in-cylinder pressure at stationary condition was transmitted to the highly non-stationary engine start-up. There, the current models for calculation of the transient wall heat fluxes were found to be misleading. Therefore, adaptations to the start-up conditions of the known models by Woschni, Hohenberg and Bargende were introduced for calculation of the wall heat transfer coefficient in SI engines with gasoline direct injection. This paper shows how the indicated values can be measured during the engine start-up.