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The reduction of harmful emissions is a key challenge in fighting climate change and global warming. Besides battery electric vehicles (BEVs), improved engine efficiency and alternate fuels, such as e-fuels or biofuels, can improve the emission budget of the transportation sector. Pred ictive simulations can be utilized as these avoid relying on slow manufacturing processes and expensive experiments. As the properties of alternative fuels can change drastically compared to classical fuels, even engine parameters, such as the mass flow rate, need to be reevaluated and optimized. However, simulation frameworks often rely on mass flow rates as input quantity, and hence, a prediction is impossible. This paper gives accurate pressure-based boundary conditions for multiphase systems and focuses on equations of state (EOS) employed in homogeneous equilibrium models (HEMs). Additionally, a dual-density approach is introduced to correct modeling errors that are intrinsic to a particular EOS.

Large-eddy simulation (LES) is an important tool to understand and analyze sprays, such as those found in engines. Subfilter models are crucial for the accuracy of spray-LES, thereby signifying the importance of their development for predictive spray-LES. Recently, new subfilter models based on physics-informed generative adversarial networks (GANs) were developed, known as physics-informed enhanced super-resolution GANs (PIESRGANs). These models were successfully applied to the Spray A case defined by the Engine Combustion Network (ECN). This work presents technical details of this novel method, which are relevant for the modeling of spray combustion, and applies PIESRGANs to the ECN Spray C case. The results are validated against experimental data, and computational challenges and advantages are particularly emphasized compared to classical simulation approaches.

Split injection processes have been analyzed by means of a Quasi-1D spray model that has been recently coupled to a laminar tabulated unsteady-flamelet progress-variable (UFPV) combustion model. The modelling approach can predict ignition delay and lift-off for long injection profiles, and it is now extended to a two-pulse injection scheme. In spite of the simplicity of the approach, relevant phenomena are adequately reproduced. In particular, the faster penetration of the second injection pulse compared to the first one is captured by the model both under inert and reacting conditions. The second pulse ignites much faster than the first one due to the injection into the remnants of the first one, where high temperature oxygen-depleted regions can be found. Ignition of the second pulse happens as soon as the first pulse reaches this region, with a faster low- to high-temperature transition.

Direct injection of gaseous fuels usually involves the presence of under-expanded jets. Understanding the physics of such process is imperative for developing Direct Injection (DI) internal combustion engines fueled, for example, by methane or hydrogen. An experimental-numerical characterization of the under-expanded jets issued from an innovative multi-hole injector, designed for application in heavy-duty engines, is carried out. The experimental characterization of the jet evolution was recorded by means of schlieren imaging technique and, then, a numerical simulation procedure was validated, allowing a comprehensive injection process analysis. A high-order and density-based solver, capable of reproducing the most relevant features of the under-expanded jets, was developed within OpenFOAM framework. Initially the effects of the upstream-to-downstream pressure ratio, namely Net Pressure Ratios (NPR), on the spray morphology were investigated.

The large difference in fuel properties between methanol and gasoline demand the development of a dedicated spark ignition (SI) engine in order to exploit methanol’s properties for maximum thermal efficiency, rather than using the flex-fuel engines of today. In order to develop such an engine, proven technologies on a high efficiency gasoline engine are a good reference point to start with. The engine setup used in this work was a 1.6l turbocharged direct injection engine equipped with variable valve timing (VVT) and a low pressure EGR loop. A central composite design (CCD) was used to quantify the influence of five control parameters on the brake thermal efficiency (BTE) and main energy losses when running the engine on methanol at full load and a fixed engine speed of 1700 rpm. The set of control parameters consisted of the intake valve opening timing, exhaust valve opening timing, opening of the waste gate, opening of the EGR valve and opening of the backpressure valve.

An experimental investigation is carried out in a single-cylinder, constant speed, low heat rejection (LHR) diesel engine to study the effects of adding N-Isopropyl-N'-phenyl-1, 4-phenylenediamine (IPPD) as on oxidant to a Jatropha Methyl Ester (JME)-diesel blend comprising 20% JME and 80% diesel (JME20) on the combustion, performance, and emission, parameters of the test engine. The investigation is carried out in the diesel engine using the following fuels: diesel, JME20, and IPPD doped JME20 in an LHR mode. Four different concentrations of IPPD viz 500 ppm, 1000 ppm, 1500 ppm, and 2000 ppm are doped with JME20 in the investigation. For LHR mode, the piston crown is coated with two layers of thermal barrier coating (TBC) materials. The first layer is NiAl coating with a thickness of 0.15 mm and another layer is YSZ+CeO2 coating with a thickness of 0.3 mm.

The carbon-neutral biodiesel is a promising renewable substitute for fossil diesel that renders the traditional oxides of nitrogen-particulate matter (NOx-PM) trade-off into a unidirectional NOx control problem. Low-temperature combustion (LTC) modes such as homogenous charge compression ignition (HCCI) are attractive for obtaining ultra-low NOx and PM emissions. Studies on utilizing biodiesel fuel for HCCI combustion mode are sparsely available. Moreover, biodiesel emulsions in the HCCI combustion mode have not been attempted so far. Based on this premise, the present work explored the potential to utilize biodiesel and its emulsions having 20% and 25% water by volume under HCCI operating conditions. Biodiesel was prepared from a non-edible Karanja oil. The biodiesel emulsions were prepared using a heated magnetic stirrer apparatus with 3% by volume of the raw Karanja oil as a surfactant.

Many efforts have been made in recent years to find renewable replacements for fossil fuels that can reduce the carbon footprint without compromising combustion performance. Bio-blendstock oil developed from woody biomass using a reliable thermochemical conversion method known as catalytic fast pyrolysis (CFP), along with hydrotreating upgrading has the potential to deliver on this renewable promise. To further our understanding of naphthenic-rich bio-blendstock oils, an improved formulation surrogate fuel (SF), SF1.01, featuring decalin and butylcyclohexane naphthenic content was devised and blended with research-grade No.2 diesel (DF2) at various volume percentages. The blends were experimentally evaluated in a single-cylinder Ricardo Hydra compression ignition engine to quantify engine and emissions performance of SF1.01/DF2 blends. Injection timing events were varied from knock limit to misfire limit at the same operating conditions for all blends.

Aromatics have long been used in pump-grade gasoline to inhibit engine knock and enhance a fuel’s octane number, therefore this study focuses on how the addition of aromatics at 2% by mole affects the ignition characteristics of a Toluene Reference Fuel (TRF). The additives investigated in this study are the substituted phenols p-cresol and 2,6-xylenol. In addition to fuel composition, exhaust gas recirculation dilution can be used to lower the combustion temperature and consequently lengthen the ignition delay time of a given fuel-air mixture. This study replicated exhaust gas recirculation dilution by using N2, as it was inert and did not interfere with reactions between the fuel and oxidizer. Determination of whether the similar structures of p-cresol and 2,6-xylenol result in different autoignition inhibiting characteristics was performed on a rapid compression machine.

In the last six decades, due to the continuous improvement in environmental legislations and depletion of fossil fuels in the world, IC engine researchers have been vigorously exploring various possibilities of reducing petroleum fuel dependency and emissions of internal combustion (IC) engines. Operating IC engines in low heat rejection (LHR) mode by providing thermal barrier coating (TBC) to some of the engine components is one of the methods to improve thermal efficiency and reduce some of the tailpipe emissions. Yttria stabilized zirconia (YSZ) is a commonly used TBC material in IC engines due to its thermal characteristics. On the other hand, running an engine in a dual-fuel operation by a gaseous fuel gives better and more efficient combustion. In this research work, an attempt was made to study the combined effects of running a compression ignition (CI) engine in dual-fuel operation with LHR mode on its performance, and emissions were investigated.

The continuous improvement of internal combustion engines (ICEs) with strategies that can be applied to existing vehicle platforms, either directly or with minor modifications, can improve efficiency and reduce GHG emissions to help achieve Paris climate targets. Low carbon fuels (LCF) as diesel substitutes for light and heavy-duty vehicles are currently being considered as a promising alternative to reduce well-to-wheel (WTW) CO2 emissions by taking advantage of the carbon offset their synthesis pathway can promote, which could capture more CO2 than it releases into the atmosphere. Additionally, some low carbon fuels, like OMEx blends, have non-sooting properties that can significantly improve the NOx-soot tradeoff. The current work studies the calibration optimization of a EU6D-TEMP light-duty engine using various LCFs with different renewable contents with the goal of reduced NOx emissions.

Commercial fleets are interested in results from experiments conducted in real operational conditions to help them quantify and understand the impact of environmental factors on fuel economy and operating costs. The goal of this study was to measure through controlled track testing and operational testing the effects of environmental conditions, particularly ambient temperature, and air density, on fuel consumption. Extensive track testing based on the SAE J1321 Fuel Consumption Test Procedure - Type II protocol with various vehicles under different test conditions showed a decrease in fuel efficiency of up to 12% for an air density variation of 7% and an ambient temperature variation of 30 °F (17 °C). Data from various and extensive operational tests were also analyzed, specifically from tests conducted using several groups of medium and heavy-duty vehicles involved in regional, local, urban transport and pick-up and delivery.

Improvements in vehicle technology impact the purchase price of a vehicle and its operating cost. In this study, the monetary benefit of a technology improvement includes the potential reduction in vehicle price from using cheaper or smaller components, as well as the discounted value of the fuel cost savings. As technology progresses over time, the value and benefit of improving technology varies as well. In this study, the value of improving a few selected technologies (battery energy density, electric drive efficiency, tire rolling resistance, aerodynamics, light weighting) is studied and the value of the associated cost saving is quantified. The change in saving as a function of time, powertrain selection and vehicle type is also quantified. For example, a 10% reduction in aerodynamic losses is worth $24,222 today but only $8,810 in 2030 in an electric long haul truck. The decrease in value is primarily due to expected battery cost reduction over time.

Rapid population growth and fuel crisis due to limited availability of fossil fuels, led the research in the fields of alternative fuel for the replacement of conventional fuels. The petroleum-like characteristics of ethanol make it an excellent alternative fuel for the internal combustion (IC) engines. It can be easily derived from waste agricultural resources such as plant biomass and forest residue, ease of production increases the possibility of its utilization locally in the agricultural engine and transport vehicles. A laboratory experiment was carried out, using a common rail direct injection (CRDI) diesel engine at varying load conditions (no-load, 20 Nm and 40 Nm) with two ethanol blends (5% and 10% v/v indicated by E05 and E10) and diesel (D100) to explore the combustion stability, combustion behaviour and emissions parameters of ethanol in existing compression ignition (CI) engine.

Methanol has a very low cetane number but it can be used in the neat form in a glow plug based hot surface ignition (HSI) engine at CI engine compression ratios. A CFD simulation model of a glow plug assisted methanol HSI engine was developed and validated using experimental data reported in literature. A study on the effect of single and multipulse injection of methanol, glow plug surface temperature, injection pressure and effect of shielding it were conducted by applying the model on to a three cylinder neat methanol HSI engine. A glow surface temperature of 1273 K was found to be sufficient for ignition of methanol at 50% load while the distance between the glow plug and the injector affected the ignition delay. The sprays were ignited sequentially starting from the one closest the glow plug which resulted in extended combustion. Injecting methanol in double pulses reduced the Maximum Rate of Pressure Rise (MRPR).

Advanced combustion engines, as power sources, dominate all aspects of the transportation sector. Stringent emission and fuel efficiency standards have promoted the research interest in advanced combustion strategies and alternative fuels. Owing to the comparable energy density to the existing fossil fuels and renewable production, alcohol and ether fuels may be a suitable replacement, or an additive to the gasoline/diesel fuels to meet the future emission standards with minimal modification to current engine geometry. Furthermore, lean and diluted combustion are well-researched pathways for efficiency improvement and reduction of engine-out emissions of modern engines. However, lean-burn or EGR dilution can introduce combustion inefficiencies in the form of excessive hydrocarbon, carbonyl species and carbon monoxide emissions.

The present work represents the continuation of the introductory study presented in part I [11] where the experimental plan, the measurement system and the tools developed for the testing of a modern Wankel engine were illustrated. In this paper the motored data coming from the subsequent stage of the testing are presented. The AIE 225CS Wankel rotary engine produced by Advanced Innovative Engineering UK, installed in the test cell of the University of Bath and equipped with pressure transducers selected for the particular application, has been preliminarily tested under motored conditions in order to validate the data acquisition software on the real application and the correct determination of the Top Dead Centre (TDC) location which is of foremost importance in the computation of parameters such as the indicated work and the combustion heat release when the engine is tested later under fired conditions.

This work represents a further contribution to reporting experimental activities carried out on a modern Wankel rotary engine. Specifically, in this study, the firing performance of the Advanced Innovative Engineering 225CS engine is analysed. Preliminary presentations of the experimental and measurement setup and a motoring analysis were extensively covered in Part I and II of this suite of papers while the current work presents the combustion analysis of the firing indicated pressure cycles collected through the bespoke combustion analyser software developed within the project. With the Wankel rotary engine gaining popularity again due to its potential as a range extender for battery electric vehicles, the aim of this work was mainly to analyse the fuel consumption together with the overall efficiency and the emissions at different engine speeds and loads as per classic steady-state engine testing.

Opposed-piston 2-stroke (OP-2S) engines have the potential to achieve higher thermal efficiency than a typical diesel engine. However, the uniflow scavenging process is difficult to control over a wide range of speeds and loads. Scavenging performance is highly sensitive to pressure dynamics, port timings, and port design. This study proposes an analysis of the effects of port vane angle on the scavenging performance of an opposed-piston 2-stroke engine via simulation. A CFD model of a three-cylinder opposed-piston 2-stroke was developed and validated against experimental data collected by Achates Power Inc. One of the three cylinders was then isolated in a new model and simulated using cycle-averaged and cylinder-averaged initial/boundary conditions. This isolated cylinder model was used to efficiently sweep port angles from 12 degrees to 29 degrees at different pressure ratios.

High pressure EGR provides NOx emission reduction even at low exhaust temperatures. To maintain a safe EGR system operation over a required lifetime, the EGR cooler fouling must not exceed an allowable level, even if the engine is operated under worst-case conditions. A reliable fouling simulation model represents a valuable tool in the engine development process, which validates operating and calibration strategies regarding fouling tendency, helping to avoid fouling issues in a late development phase close to series production. Long-chained hydrocarbons in the exhaust gas essentially impact the fouling layer formation. Therefore, a simulation model requires reliable input data especially regarding mass flow of long-chained hydrocarbons transported into the cooler. There is a huge number of different hydrocarbon species in the exhaust gas, but their individual concentration typically is very low, close to the detection limit of standard in-situ measurement equipment like GC-MS.