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Mixtures of few representative hydrocarbon species are often used in computational studies as surrogates of market petroleum fuels, which contain hundreds of components. While this simplification is imperative for computational costs of reaction kinetics, it introduces unavoidably uncertainties in simulations. Differences between the real and the surrogate fuels regarding mixture formation, oxidation chemistry, and fuel composition contribute to such uncertainties. An evaluation of the underlying concept of a surrogate fuel model in terms of engine performance is thus of high interest. This paper presents an experimental study with a spark-ignition (SI) single-cylinder engine (SCE) to compare the combustion and emission characteristics between a market gasoline fuel and its corresponding four-component surrogate (iso-octane, n-heptane, toluene, ethanol). The measurements cover a wide range of operating points in terms of engine load, speed, air-to-fuel ratio, and operating conditions. Together with standard performance and emission measurements, a non-standard hydrocarbons (HC) analysis has been performed with a fast flame ionization detector and an ion-molecule-reaction mass spectrometer. The comparison reveals very good agreement between the market gasoline and the surrogate fuel regarding combustion and global gaseous emission behaviors, with an average deviation for almost all of the analyzed quantities below 2%. The comparison of CO emissions in stoichiometric operation presents a higher scatter, due to the high sensitivity of the CO emissions on mixture formation and fuel volatility. The different compositions of the two fuels also lead to deviations of speciated-HC emissions, which is confirmed by mass spectrometry. Additionally, the sooting tendency of the surrogate fuel is found to be more than 10 times lower compared to the market gasoline fuel.

Driving cycles like WLTP and the consideration of real driving emissions increase the relevance of load-dependent process losses for the prediction of engine efficiency based on engine process simulation. The contribution of valve pumping work to the total gas exchange losses of an internal combustion engine is usually neglected during engine conception. However, its share of the total gas exchange power losses increases with engine load. Within this paper, the variation of load, engine speed and valve timings on valve pumping work is investigated on a theoretical basis using 1D-CFD-simulation for a three-cylinder turbo-charged gasoline engine. Further, the influence of the valve lift curve design on valve pumping work is evaluated. The consideration of valve pumping work can increase the accuracy of the engine efficiency prognosis based on engine process simulations. A comparison with results from the literature points out that 3D-CFD-based evaluations of the valve gas forces can provide even more accurate results than the conventional calculation approach which is presented within scope of this publication. Hence, future works on this subject might include the improvement of the standard calculation approach on an either physical or empirical basis considering valve and seat ring design details as parameters.

Homogeneous charge compression ignition has the potential to significantly reduce NO x emissions, while maintaining a high fuel efficiency. Homogeneous charge compression ignition is characterized by compression-induced autoignition of a lean homogeneous air–fuel mixture. Combustion timing is highly dependent on the in-cylinder state including pressure, temperature and trapped mass. To control homogeneous charge compression ignition combustion, it is necessary to have an accurate representation of the gas exchange process. Currently, microprocessor-based engine control units require that the gas exchange process is linearized around a desired operating point to simplify the model for real-time implementation. This reduces the models’ ability to handle disturbances and limits the flexibility of the model. However, using a field programmable gate array, a detailed simulation of the physical gas exchange process can be implemented in real time. This paper outlines the process of converting physical governing equations to an offline zero-dimensional gas exchange model. The process used to convert this model to a field programmable gate array capable model is described. This model is experimentally validated using a single cylinder research engine with electromagnetic valves to record real-time field programmable gate array gas exchange results and comparing to the offline zero-dimensional physical model. The field programmable gate array model is able to accurately calculate the cylinder temperature and cylinder mass at 0.1 °CA intervals during the gas exchange process for a range of negative valve overlaps, boost conditions and engine speeds making the model useful for future real-time control applications.

Journal of power sources 537, 231394 (2022). doi:10.1016/j.jpowsour.2022.231394, Published by Elsevier, New York, NY [u.a.]

Catalysis letters (2021). doi:10.1007/s10562-021-03771-w, Published by Springer Science + Business Media B.V, Dordrecht [u.a.]

The well-to-wheel environmental impacts of blending electricity-based polyoxymethylene ethers of chain length three to five (OME3-5) with fossil diesel are evaluated, depending on the availability and the environmental impacts of electricity for fuel production. OME3-5 is considered a promising substitute and blending component for fossil diesel. We account for the entire life cycle of production, blending, and use of OME3-5 with fossil diesel, considering alternative blending ratios and combustion emissions from single-cylinder engine tests. For OME3-5 production, our analysis identifies an aqueous route via methanol and formaldehyde as the route with the highest exergy efficiency and the lowest environmental impacts among four considered routes. In terms of the carbon footprint of the entire life cycle, diesel-OME3-5 blends can only compete with fossil diesel if low-carbon electricity is used for the supply of electricity-based feedstocks and energy. With low-carbon electricity being available, an increased blending ratio of OME3-5 with fossil diesel reduces the carbon footprint as well as NOx and soot emissions. The actual reduction potential additionally depends strongly on the blending ratio. Since low-carbon electricity is limited, it should be used in such a way that environmental impacts are minimal. For the electricity-based fuel OME3-5, this is achieved when distributing OME3-5 as a blend component to all fleet vehicles simultaneously instead of switching only a few vehicles to pure OME3-5, i.e., "blend for all" is favorable over "pure for few.", Sustainable Energy & Fuels, 6 (8), ISSN:2398-4902

Future internal combustion engines using novel fuels and combustion systems have the potential to achieve ultra-high efficiency and lowest pollutant emissions to comply with future regulatory requirements. Realizing indicated efficiencies over 50% with ultra-lean low temperature combustion face new challenges. To meet this goal, hydrocarbon (HC) and carbon monoxide (CO) emissions need to be reduced significantly further. To do this, knowledge must be gained about how the operation regime of the engine affects the HC and CO emissions. Since these emissions partly originate from areas where flame quenching occurs, an investigation of the gases near the wall is of interest. To this end a fast gas sampling method is being developed to extract and analyze the gas from the combustion chamber. The used fast gas sampling valve from Kistler enables sampling durations of less than 1 ms. Fourier-transform-infrared spectroscopy and a fast mass spectroscopy allow the determination of the sample composition. The valve is positioned inside the cylinder head of a single cylinder engine between intake and exhaust valves. In order to assess the effects of engine operating conditions on the formation of HC and CO at the cylinder walls, the measurement uncertainty of the setup must be evaluated. Since the combustion process is subject to cyclic variations, the evaluation of only a few individual measurements is not meaningful. Therefore, mean values are determined from the evaluation of several measurements not performed consecutively. By examining the mean and standard deviation of these measurements for each species, one can determine a measurement error. In comparison, lean operation with RON95E10 fuel at an IMEP = 12 bar and an engine speed of n = 2000 1/min shows a significant reduction in intermediate hydrocarbon species such as acetylene and a significant increase in fuel species such as ethanol compared to stoichiometric operation.

Catalysts : open access journal 11(11), 1339 (2021). doi:10.3390/catal11111339 special issue: "Special Issue "New Challenges in Electrocatalysts for Fuel Cells and Hydrogen Production" / Special Issue Editors: Dr. Davide Clematis, Guest Editor; Prof. Dr. Fabrice Mauvy, Guest Editor; Dr. Jan Van Herle", Published by MDPI, Basel

The increasingly stringent limits on pollutant emissions from internal combustion engine-powered vehicles require the optimization of advanced combustion systems by means of virtual development and simulation tools. Among the gaseous emissions from spark-ignition engines, the unburned hydrocarbon (HC) emissions are the most challenging species to simulate because of the complexity of the multiple physical and chemical mechanisms that contribute to their emission. These mechanisms are mainly three-dimensional (3D) resulting from multi-phase physics - e.g., fuel injection, oil-film layer, etc. - and are difficult to predict even in complex 3D computational fluid-dynamic (CFD) simulations. Phenomenological models describing the relationships between the physical-chemical phenomena are of great interest for the modeling and simplification of such complex mechanisms. In addition, phenomenological models can be applied within simplified simulation environments, e.g., 0D-1D engine simulations, to enable predictions of HC emissions for a wide range of operating conditions. In this work, the development of phenomenological models to account for HC emissions from piston top-land crevices, wall flame quenching, and oil-film adsorption/desorption mechanisms is explained in detail. The model development is based on measurements and models from a single cylinder direct injection (DI) spark ignition (SI) research engine. Common modeling hypotheses and approaches from literature have been verified and further developed with 3D-CFD simulations. In particular, assumptions regarding local temperature and air-fuel ratio, which are necessary for HC modeling, have been developed on the basis of a zone post-processing of the 3D-CFD results. Additionally, a novel approach to describe HC post-oxidation, which is based on 0D-chemistry calculations, has been developed. The HC models have been implemented within a GT-POWER model of the engine in conjunction with a 0D two-zone combustion chamber description. The accuracy of the developed models has been tested against a large experimental database with varying engine load, speed, air to fuel ratio, valve timing, and oil/coolant temperature. The deviation in the HC emission prediction is mainly within 20% at warm engine operation. Higher deviations are observed at cold engine conditions because of the absence of secondary HC models which have not been considered in the present work.

Gasoline particulate filters (GPF) recently entered the market and are already regarded as state-of-the-art for gasoline exhaust aftertreatment systems to enable EU6d-TEMP fulfillment and beyond. Due to its rapid market introduction, the field of GPF lifetime evaluation is still open for research. In this context, the paper describes the advantages of a method for accelerated investigation of filter ash loading during the development of particulate filters. The central task is the simulation of real-world lubrication oil consumption and combustion, which is the major source of ash in the exhaust gases. For that purpose, a burner test bench designed for catalyst aging was additionally equipped with an oil injection unit. The injection unit enables control of the oil volume and the droplet sizes as precursors for the ash particulates. The results obtained with the new filter aging method are compared with data from vehicle endurance runs and with burner test investigations in which the fuel is doped with oil. The latter method is currently considered as the state-of-the-art method for accelerated ash generation. The new method proofed to be vehicle-equivalent in terms of ash-induced backpressure, filtration efficiency, wall ash layer formation, and wall/plug ash ratio. In this context, it turned out that it is important not to atomize the oil droplets too far, since smallest particulates accumulate mainly at the walls and cause unrealistically high backpressures. Furthermore, the ash loading process should include different mass flows in order to achieve stable backpressure results.

We demonstrated recently that NO concentration measurements are feasible even in the core of largely non-sooting diesel-like jets by combined laser-induced fluorescence (LIF) and spontaneous Raman scattering (SRS). However, the question arises whether previous findings hold also for other diesel-like jets. The current study focuses on fuel effects. In the previous NO measurements, n-heptane was used. It is replaced by pure di-n-butylether (DNBE) and a tailor-made blend of 50% DNBE and 50% n-octanol. These fuels are promising biofuel candidates and lead to an interesting variation of mixing during combustion (MDC). The determination of NO concentrations turns out to be generally feasible with the blend on the jet centerline in the quasi-steady phase of the injection event. The corresponding uncertainty is about ± 28 %. By contrast, some of the NO-LIF measurements in sooting DNBE jets are discarded, primarily due to increased light attenuation. For the remaining NO concentrations with DNBE the corresponding uncertainty is about ± 40 %. For the blend, results indicate that NO formation is very similar to the one in the n-heptane jets. Thus, the net effect of changed volatility and oxygenation is seemingly weak. By contrast, quasi-steady centerline NO concentrations are apparently significantly affected by MDC for pure DNBE. Relatively high NO concentrations are observed in this case, although products of highly fuel-rich fluid parcels are also present there. This study indicates the importance of MDC in such jets.

E-Fuels can play a significant role in decarbonizing the transport sector. Among the potential E-fuels, dimethyl ether is a promising candidate for the combustion in compression ignition engines. Together with methanol, it can be produced from synthesis gas in a combined single-step process. However, due to the low volumetric heating value of dimethyl ether, the fuel injection system has to be modified to realize higher fuel flow rates. In this study, two injectors with increased nozzle hole diameters have been investigated, and their impact on engine performance, particle number distribution and formaldehyde as well as methane emissions was assessed. It was found that with dimethyl ether as fuel, the indicated efficiency at high load could be increased by over 1% compared to operation with conventional diesel fuel. The main reason for this is lower wall heat loss. Furthermore, almost no particle emission was found during dimethyl ether operation with the smaller nozzle. With the larger nozzle hole diameter, increased particle concentrations were measured at high loads. But these were still much lower compared to the corresponding diesel fuel combustion. Regarding formaldehyde and methane, higher emissions were found for the dimethyl ether combustion compared to diesel fuel combustion. It is assumed that this is due to the increased formaldehyde and methane production of dimethyl ether during high temperature pyrolysis and oxidation. The increased hydrocarbon emissions could have been caused by fuel dripping from the nozzle after the end of the injection event.

Dimethyl ether is a gaseous fuel which can easily be liquefied under moderate pressures. Its high reactivity makes it suitable for combustion in a compression ignition engine, and due to the high oxygen content, its combustion is virtually free of soot. The high oxygen content and low density of dimethyl ether lead to a lower volumetric heating value compared to Diesel fuel. Therefore, the hydraulic flow rates of the injectors have to be increased with larger nozzle holes. The influence of larger nozzle holes on the dimethyl ether spray formation and ignition are presented in this article. Experimental investigations were conducted at a constant-pressure vessel with optical access and with a single-cylinder research engine. Subsequently, a numerical optimization of the piston bowl and injector nozzle has been carried out. A very fast air/fuel mixture formation with dimethyl ether was observed, which leads to a lean combustion with small nozzle diameters. With increasing nozzle diameters, the combustion moves toward stoichiometric conditions and with very large diameters to rich combustion conditions. The ignition delay for small diameters is mostly dominated by the lean mixture, and for large diameters, the ignition delay is strongly influenced by cooling effects. For the optimization, the oxidation potential number was maximized, which proved suitable to simultaneously increase efficiency and reduce emissions. A conventional ω-shaped bowl and a step bowl have been optimized, and large bowl diameters were found to be beneficial for dimethyl ether combustion. Furthermore, nozzle diameters around 150 µm showed the most promising results. Compared to the dimethyl ether reference, the simulations with the optimized ω-shaped bowl showed a power increase of 2.7%. Experimentally, the optimized ω-shaped bowl in combination with the reference injector showed an efficiency increase by more than 1% at 2000 r/min full load compared to the dimethyl ether reference.

In this paper, the potential of alternative fuels to reduce preignition in engines is primarily investigated. Two ketones (2-butanone and 3-methylbutanone), a furan (2-methylfuran), and five alcoho...

Homogeneous charge compression ignition is a part-load combustion method, which can significantly reduce oxides of nitrogen (NO x) emissions compared to current lean-burn spark ignition engines. The challenge with homogeneous charge compression ignition combustion is the high cyclic variation due to the lack of direct ignition control. A fully variable electromagnetic valve train provides the internal exhaust gas recirculation through negative valve overlap which is required to obtain the necessary thermal energy to enable homogeneous charge compression ignition. This also increases the cyclic coupling as residual gas and unburnt fuel is transferred between cycles through exhaust gas recirculation. To improve combustion stability, an experimentally validated feed-forward water injection controller is presented. Utilizing the low latency and rapid calculation rate of a field programmable gate array, a real-time calculation of residual fuel mass is implemented on a prototyping engine controller. Using this field programmable gate array–based calculation, it is possible to calculate the amount of fuel and the required control interaction during an engine cycle. This controller prevents early rapid combustion following a late combustion cycle using direct water injection to cool the cylinder charge and counter the additional thermal energy from any residual fuel that is transferred between cycles. By cooling the trapped cylinder mass, the upcoming combustion phasing can be delayed to the desired setpoint. The controller was tested at several operating points and showed an improvement in the combustion stability as shown by a reduction in the standard deviation of combustion phasing and indicated mean effective pressure.

Oxymethylene ether (OMEn) has recently drawn high attention due to its high pollutant emission reduction potential and the sustainable synthesis pathways involving carbon capture and renewable hydrogen. In this work, five blends of OMEn in diesel fuel in addition to pure OME3-5 and diesel fuel as reference were investigated in a single cylinder engine. Each OMEn-Diesel blend was prepared with a different chain length, ranging from OME1 to OME5. The blending ratio of OMEn in fossil diesel fuel was set to 35 vol%, corresponding to a ∼23.5% diesel fuel substitution on a heating value basis. We find that OMEn contributes to improved oxidation conditions, resulting in a more complete combustion compared to conventional diesel fuel operation. This is reflected by reduced emissions of unburned hydrocarbons and carbon monoxide (up to 90%), higher burned mass fractions after the main combustion phase, higher indicated efficiencies (up to +3%) and lower exhaust gas temperatures (up to −70 °C). Furthermore, while pure OMEn burns soot-free, a significant soot reduction was measured for the OMEn-Diesel blends. Based on the findings of this work, it is concluded that from a combustion and emission point of view, the OMEn chain length is of minor importance for applications where OMEn is blended with diesel fuel up to a ratio of 35 vol%. Thus, the main considerations for an optimal OMEn chain length range should focus on aspects like fuel properties and OMEn synthesis. In this regard, a simple and efficient synthesis process (e.g. synthesis of OME1) must be weighed up against favorable fuel properties of the synthesis product (e.g. OME3-5). Hence, bearing in mind that OMEn is not a drop-in fuel and will always demand a dedicated engine, the preference of long chain OMEn over OME1 is not straight forward and strongly depends on the application.

Predictive energy management has become a new focus of the automobile industry for its high potential of further reducing energy consumption. Based on previous works on predictive speed optimization using discrete dynamic programming (DDP), this paper introduces a novel approach of applying DDP with variable step size in stage variable discretization, which can realize a better tradeoff between precision and computational cost. In this approach, a “meshing” algorithm searches the points of interest (POI), such as speed limit change, traffic lights, and road curvatures, where changes in vehicle speed are expected. The algorithm increases the step-size resolution close to these points and reduces the resolutions in positions further away from POI, where the optimized vehicle speed is insensitive to the step size. With this approach, the position of POI can be precisely located to solve the DDP problem. In a test case with a relatively high density of POI, the computational cost is reduced by more than 53% by only sacrificing less than 1% of precision compared to a fixed step-size discretization with high resolutions. It can be expected that, with a lower density of POI, the computational cost will be reduced even further.

Innovative Solutions for Energy Transitions / Edited by Jinyue Yan, Hong-xing Yang, Hailong Li, Xi Chen 10th International Conference on Applied Energy, ICAE 2018, Hong Kong, Peoples R China, 22 Aug 2018 - 25 Aug 2018; Amsterdam [u.a.] : Elsevier, Energy procedia 158, 2806-2811 (2019). doi:10.1016/j.egypro.2019.02.042, Published by Elsevier, Amsterdam [u.a.]

3-Hydroxy decanoic acid (3-HDA), derivable from glucose or xylose waste-streams, was successfully upgraded electrochemically into a drop-in oxygenate with promising fuel characteristics. Properties such as a cetane number of 63 together with a suitable flash point and cold filter plugging point qualify the mixture for high blending ratios with fossil diesel or Fischer–Tropsch diesel. The individual C9 oxygenates are otherwise only accessible by hydroformylation. Under optimised conditions, anodic decarboxylation of 3-HDA allowed near full conversion and over 95% total yield after 30 minutes. Further, direct electrochemical 3-HDA conversion of a fermentation broth was demonstrated. This allows for a substantial reduction of unit operations and energy requirements, highlighting the potential of integrating electrochemistry and biotechnology into future bio-refineries.

Within the cluster of excellence “Tailor-Made Fuels from Biomass” diethoxymethane (DEM) was identified as a promising fuel candidate from a production perspective. Synthesized by combining a bio-based feedstock and C O 2 as carbon source together with “green hydrogen” from water electrolysis DEM is defined as “bio-hybrid fuel” . To determine the molecules general applicability to a combustion system and to develop up combustion models a rapid screening of the ignition characteristics is performed in a rapid compression machine and a shock tube. Those suggest DEM being a potential fuel for gasoline controlled autoignition (GCAI) because of a relatively wide range of temperature independent ignition delay, a good autoignition behavior compared to conventional gasoline fuel and a multi-stage ignition behavior. To test the suitability of those molecules as a fuel and determine possible improvements to the production side, DEM was used in a single cylinder research engine operated in GCAI combustion mode. Compared to GCAI combustion with conventional RON95 E10 fuel, DME shows a significantly decreased ignition delay. As a consequence, the internal residual gas fraction, whose enthalpy is used to initiate autoignition, can be reduced and combustion stability is increased. Starting from similar combustion phasing using external exhaust gas recirculation to align the ignition behavior of DEM and RON95 E10, a variation of the intake temperature reveals that DEM has the potential to reduce the sensitivity of the combustion system.

Di-n-butyl ether (DNBE) and n-octanol have very low sooting tendencies in diesel-like combustion, as demonstrated in previous engine studies. This finding is not fully understood for pure DNBE, because it has a very high cetane rating (∼100). In order to investigate the underlying mechanisms, the structure of diesel-type jets is analyzed by a number of optical diagnostics, such as spontaneous Raman scattering (SRS), laser-induced fluorescence (LIF), OH* luminescence imaging, Mie scattering, and shadowgraphy. Pure DNBE and a tailor-made blend of 50% DNBE and 50% n-octanol as well as neat n-heptane are used as the fuel in separate experiments. The jets are probed in a simulated engine-like environment in a high-pressure combustion vessel. In particular, the inner flame structure is analyzed by SRS and LIF. This yields information on the local temperature and the concentrations of O2, CO, and polycyclic aromatic hydrocarbons (PAH). For the first time, O2 is quantitatively detected in the core of a diesel-like flame by resonance-enhanced SRS. Thereby, air entrainment into the inner flame core is assessed. Results show that air entrainment is particularly strong for pure DNBE, explaining its high soot oxidation rate and overall low sooting tendency. High entrainment is primarily attributed to the low heat-release rate of DNBE, which is likely an effect of its high ignitability. Thus, it can be concluded that the high cetane rating of pure DNBE does not only lead to relatively poor pre-combustion mixture preparation and consequently considerable soot formation but seemingly also to particularly strong soot oxidation. Moreover, the jet structure turns out to be very similar for the DNBE/n-octanol blend and neat n-heptane, indicating that the net effect of volatility and fuel oxygenation is weak.

It was demonstrated recently that quantitative temperature and CO measurements can be conducted by spontaneous Raman scattering (SRS) in non-sooting diesel-like biofuel jets in a vessel. In contrast, n-heptane is used as the fuel in the present study. This leads to slightly increased sooting tendency. One-dimensional temperature and CO measurements are generally performed successfully. Fuel-injection pressure is varied and the flame structure is characterized, including the jet core. Effects of pre-combustion mixture inhomogeneity are particularly observed at lower injection pressure (700 bar). Strong deviations from adiabatic-equilibrium conditions in terms of temperature and CO mole fraction are observed in particularly fuel-rich fluid parcels. CO formation is apparently affected by turbulent mixing there. Relatively low temperatures are measured around the flame lift-off region, in particular for the highest injection pressure (1500bar), indicating turbulence-chemistry interaction.

Within the Research Cluster of Excellence “Tailor-Made Fuels from Biomass” at RWTH Aachen University, novel fuels from biomass for internal combustion engines are investigated. The new fuels tend to soot less, which allows to increase exhaust gas recirculation for reduction of nitrogen oxides (NOx) emissions. This increases the emissions of unburnt hydrocarbons (HC), while the composition of the HC emissions changes because of the changed fuel composition. The impact of 16 different oxygen-free and oxygenated hydrocarbons (1-octanol, di-n-butyl ether (DNBE), 2-butanone and ethanol as examples for bio-derived fuels; toluene and n-heptane as examples for conventional fuels’ components; propane, propene, ethane, ethene, ethyne, methane, n-butane, isobutane, n-pentane and 2-propanol as HC known to be in exhaust gases) on a series production Pt–Pd/Al2O3 oxidation catalyst on a cordierite substrate has been investigated regarding adsorption and temperature programmed oxidation (TPO). In general, due to higher polarity oxygenated HC are stronger adsorbed than oxygen-free ones. For 1-octanol, an extraordinary high adsorption could be observed associated with vigorous exothermal oxidation reaction during TPO. Additionally, the temperature programmed desorption of 1-octanol and ethanol has been investigated by Diffuse Reflectance Infrared Fourier Transform Spectroscopy (TP-DRIFTS). Adsorbed alcohol species as well as oxidized products were demonstrated to be present.

Applied energy 231, 757-767 (2018). doi:10.1016/j.apenergy.2018.09.106, Published by Elsevier Science, Amsterdam [u.a.]

[EN] This experimental work evaluates the potential of 1-octanol, di-n-butyl ether and three intermediate blends as substitutes of the diesel fuel to be used in compression ignition engines. For this purpose, performance and engine-out emissions measurements have been done in a single-cylinder engine of 0.39 L displacement and 15:1 compression ratio at four engine operating conditions representative of the new European driving cycle (NEDC) driving cycle. The tests have been done keeping constant the NOx emissions and combustion center for all the fuels at each operating point. To achieve this, the exhaust gas recirculation rate and the start of injection timing were modified simultaneously for each fuel tested, while the rest of the engine settings were kept constant. All the biomass-derived fuels have the same oxygen content but substantially different cetane number and volatility. The results show that, for the same NOx levels, all the fuels allow a substantial reduction of the soot emissions versus diesel due to both the higher oxygen content in the fuel molecule and/or the extended mixing time achieved because of the lower fuel reactivity. In terms of efficiency, all the alternative fuels improve the fuel-to-work conversion efficiency. This benefit comes from decreasing the heat transfer in a greater way than the exhaust losses increase. Moreover, in general terms, all the fuels promote a reduction of the combustion losses to halve of those found with diesel., The authors gratefully acknowledge FEDER and Spanish Ministerio de Economía y Competitividad for partially supporting this research through TRANCO project (TRA2017-87694-R). This work was performed as part of the Cluster of Excellence Tailor-Made Fuels from Biomass, which is funded by the Excellence Initiative by the German federal and state governments to promote science and research at German universities. Thus, the authors would like to thank the Institute for Combustion Engines, RWTH Aachen University, for all the support to perform the research activities.

With the further tightening of emission regulations and the introduction of real driving emission tests (RDE), the simulative prediction of emissions is becoming increasingly important for the development of future low-emission internal combustion engines. In this context, gas-exchange simulation can be used as a powerful tool for the evaluation of new design concepts. However, the simplified description of the combustion chamber can make the prediction of complex in-cylinder phenomena like emission formation quite challenging. The present work focuses on the prediction of gaseous pollutants from a spark-ignition (SI) direct injection (DI) engine with 1D–0D gas-exchange simulations. The accuracy of the simulative prediction regarding gaseous pollutant emissions is assessed based on the comparison with measurement data obtained with a research single cylinder engine (SCE). Multiple variations of engine operating parameters – for example, load, speed, air-to-fuel ratio, valve timing – are taken into account to verify the predictivity of the simulation toward changing engine operating conditions. Regarding the unburned hydrocarbon (HC) emissions, phenomenological models are used to estimate the contribution of the piston top-land crevice as well as flame wall-quenching and oil-film fuel adsorption-desorption mechanisms. Regarding CO and NO emissions, multiple approaches to describe the burned zone kinetics in combination with a two-zone 0D combustion chamber model are evaluated. In particular, calculations with reduced reaction kinetics are compared with simplified kinetic descriptions. At engine warm operation, the HC models show an accuracy mainly within 20%. The predictions for the NO emissions follow the trend of the measurements with changing engine operating parameters and all modeled results are mainly within ±20%. Regarding CO emissions, the simplified kinetic models are not capable to predict CO at stoichiometric conditions with errors below 30%. With the usage of a reduced kinetic mechanism, a better prediction capability of CO at stoichiometric air-to-fuel ratio could be achieved.

This chapter provides a short overview of the three most important transportation technologies: automotive, aerospace, and rail. It initially examines the economic impact of transportation. A strong economy is usually highly dependent on the transportation of people and goods. The effects of environmental and safety legislation on transportation technologies are also discussed. Processes that will transform transportation over the coming decades are then considered.

[EN] The approach of this research is to enlarge the knowledge about the methodologies to increase the maximum achievable load degree in the context of gasoline CAI engines. This work is the continuation of a previous work related to the study of the water injection effect on combustion, where this strategy was approached. The operating strategies to introduce the water and the interconnected settings were deeply analyzed in order to optimize combustion and to evaluate its potential to increase the maximum load degree when operating in CAI. During these initial tests, the engine was configured to enhance the mixture autoignition. The compression ratio was high compared to a standard gasoline engine, and suitable fuel injection strategies were selected based on previous studies from the authors to maximize the reactivity of the mixture, and get a stable CAI operation. Once water injection proved to provide encouraging results, the next step dealt in this work, was to go deeper and explore its effects when the engine configuration is more similar to a conventional gasoline engine, trying to get CAI combustion closer to production engines. This means, mainly, lower compression ratios and different fuel injection strategies, which hinders CAI operation. Finally, since all the previous works were performed at constant engine speed, the engine speed was also modified in order to see the applicability of the defined strategies to operate under CAI conditions at other operating conditions. The results obtained show that all these modifications are compatible with CAI operation: the required compression ratio can be reduced, in some cases the injection strategies can be simplified, and the increase of the engine speed leads to better conditions for CAI combustion. Thanks to the analysis of all this data, the different key parameters to manage this combustion mode are identified and shown in the paper., The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This research work was part of the Research Unit (Forschergruppe) FOR 2401 Optimization based Multiscale Control for Low Temperature Combustion Engines, funded by the German Research Association (Deutsche Forschungsgemeinschaft, DFG). The support for this research is gratefully acknowledged.