bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Minimum Area Piston for Compression Ignition Engines
Authors: Leach Felix , Davy Martin , Ayyapureddi Sridhar , Pierson Steven , San Primitivo Rodriguez Juan , Sammut Gilbert 
Published: December 2024

Abstract
Conventional compression ignition (diesel) engine combustion system, employ pistons with omega shaped bowls (or a very similar shape) combined with a swirl-based bulk air motion to ensure good fuel-air mixing. However, such bowls have a relatively large surface area:volume ratio, leading to significant heat loss, and are complex to design and manufacture. Recent advances in fuel injection technology, allowing higher injection pressures and multiple injection events and digital rate shaping, along with variable intake valve technology mean that achieving sufficient fuel-air mixing may now not require an omega shaped bowl. This work, then, introduces a new piston design for compression ignition engines that minimises the surface area:volume ratio, enabling less heat loss through the piston, higher durability, and a lighter and easier to produce piston.
This novel piston design is evaluated against a conventional (omega) bowl piston (maintaining compression ratio and other parameters) at a variety of part and full load conditions in a single cylinder research engine. Emissions, fuel consumption, and combustion parameters are measured and presented alongside an energy balance. The results show that, depending on the load conditions, a 1.5–4% decrease in fuel consumption is noted alongside, at some load conditions, an increase in exhaust temperature (providing extra enthalpy for a turbocharger). The energy balance showed less energy lost to the oil with more energy in the exhaust.
Knock Prediction for Ammonia/Hydrogen SI Engine
Authors: Benzinger Steffen , Grill Michael , Casal Kulzer Andre , Kurien Caneon , Hurault Florian , Foucher Fabrice , Bréquigny Pierre , Mounaïm-Rousselle Christine 
Published: December 2024

Abstract
Hydrogen addition in ammonia is one attractive solution to manage all operating conditions of future ammonia engine. But even if ammonia is strongly resistive to auto-ignition, the presence of hydrogen can as a function of the thermodynamic conditions related to the compression ration induce the knock occurrence. So far, only one recent study is focused on this phenomenon based only on simulations without any experimental data. Even if the kinetics of ammonia oxidation is more and more understood, for example about 40 kinetic mechanisms are now available, there is still a lack of experimental data at pressure and temperature conditions representative to engine operating conditions. The objective of this study is to provide first knocking measurement for ammonia/hydrogen blend (90%/10% in vol.) and to improve a OD model of knock, developed previously for conventional gasoline. This has been made after selecting one of the kinetic schemes that best predicts ignition delay at relevant conditions for engines and obtained in a Rapid Compression machine. For the validation of the auto-ignition model, the onset of knocking in single working cycles is determined and compared with the modelled auto-ignition onset. To validate the knock criterion, the crank angle where 50% of the fuel is burnt is compared between predicted and measured values in the case of engine speed of 1000 rpm and as a function of different intake temperatures and pressures conditions. This validated prediction of the knock boundary of an operating point is extremely important for the development of future ICE concepts with ammonia/hydrogen blends.
An Experimental Investigation on Combustion and Emissions of a Hydrogen Enriched Ammonia-Diesel Dual Fuel Engine at a Medium Load Condition
Authors: Guo Hongsheng , Liko Brian , Stevenson David , Austin Kevin 
Published: December 2024

Abstract
As a carbon-free hydrogen carrier, ammonia is easy to store, handle and distribute compared to hydrogen itself. Switching from diesel to green ammonia in heavy-duty compression ignition engines dominating the power generation of freight transportation industry has the potential to reduce greenhouse gas (GHG) emissions. However, due to the low flame speed and presence of fuel-bound nitrogen, ammonia combustion may result in certain unburned ammonia slip and nitrous oxide (N2O) emissions, which offsets its zero-carbon advantage in applications. In this paper, an investigation on the influence of hydrogen blending on ammonia slip and emissions of nitrogen oxide (NO), N2O and GHG in a heavy-duty ammonia-diesel dual fuel engine is experimentally conducted at a medium engine load, various hydrogen blending ratios, and different gaseous fuel energy fractions. The results reveal that hydrogen blending does help significantly reduce ammonia slip. However, hydrogen blending does not help reduce N2O emissions at relatively lower gaseous fuel energy fractions that result in lower equivalence ratio for hydrogen/ammonia mixture, but does help reduce N2O emissions at relatively larger gaseous fuel energy fractions. As a result, hydrogen blending does not help reduce GHG emissions at relatively lower gaseous fuel energy fractions, but does help at higher gaseous fuel energy fractions. Blending of a small amount of hydrogen significantly improves engine efficiency, but the effect of further increasing hydrogen blending ratio on engine efficiency is insignificant. A side effect of hydrogen blending is that it increases NO emissions, since it not only increases combustion temperature but also promotes the NO formation via fuel route during ammonia combustion.
SCR+ASC Performance During a Period of Late Diesel Injection for DPF Regeneration
Authors: Ovaska Teemu , Spoof-Tuomi Kirsi , Niemi Seppo , Valkjärvi Pauli , Mikulski Maciej , Lehtoranta Kati , Alanen Jenni , Happonen Matti , Maunula Teuvo 
Published: December 2024

Abstract
More efficient removal of nitrogen oxides and particulate matter from off-road diesel engines is needed for the future emission requirements (CARB Tier 5). The dual-SCR system is proposed to enhance low-temperature performance by adding a second SCR catalyst near the engine, in addition to the main SCR catalyst located after the diesel oxidation catalyst (DOC) and particulate filter (DPF). However, the regular regeneration of the DPF must be taken care of by injecting diesel fuel so that the excess hydrocarbon that ends up in the DOC+DPF oxidizes the carbon-containing particles at high temperatures. This study used late diesel injection during the DPF regeneration period of a high-speed, common-rail diesel engine. In addition to the US EPA Tier 4F compatible off-road engine, the experimental setup included the exhaust after treatment system (SCR, DOC, DPF) installed into the insulated exhaust line in laboratory environment. Steady-state experiments were conducted to assess how late diesel injection affects vanadium-SCR and ammonia slip catalyst performance, with the SCR inlet temperatures from 250 to 400 °C. The study’s overall conclusion is that the late diesel injection strategy through a vanadium-ccSCR catalyst is viable for particulate filter regeneration only when SCR inlet temperatures are sufficiently high (≥ 320 °C). At lower temperatures, hydrocarbons from late diesel injection might cause exothermic reactions in the SCR, leading to a notable reduction in its deNOx performance.
Comprehensive Life Cycle Analysis of Diverse Hydrogen Production Routes and Application on a Hydrogen Engine
Authors: Accardo Antonella , Gentilucci Gaia , Spessa Ezio 
Published: December 2024

Abstract
In the effort of achieving net-zero Greenhouse Gas (GHG) emissions, hydrogen is becoming increasingly relevant in several sectors such as automotive, cogeneration, maritime, off-road, and railroad. However, hydrogen can be produced from different routes that involve different production processes and feedstocks. In contrast to the key role of hydrogen in the transport sector’s decarbonization, publications that claim to address the environmental impacts of hydrogen are often focused on Global Warming Potential (GWP) and GHG emissions only. This manuscript focuses on the environmental impacts of hydrogen production considering different production routes (i.e., Steam Methane Reforming (SMR), SMR coupled with Carbon Capture and Storage (CCS), Coal Gasification (CG), CG coupled with CCS, electrolysis from fossil fuels and from wind) and a broad set of environmental impact categories, not only GWP. The Life Cycle Assessment (LCA) methodology is applied in the present study with a twofold aim. The first aim is to develop the LCA models of diverse hydrogen production routes and address present and potential well-to-tank environmental impacts. The second aim is to apply the previous findings to develop a cradle-to-grave LCA of a hydrogen engine, serving as a case study for the automotive sector. The LCA models are developed using SimaPro v.9.4.0.3 as LCA software and Ecoinvent v3.8 as background database. The functional units are 1 kg of hydrogen for the cradle-to-gate boundary and 1 mile of vehicle lifetime for the cradle-to-grave boundary. The life cycle impact assessment method is the TRACI 2.1 method developed by the US Environmental Protection Agency.
Investigation of Fuel Passage Geometry on Performance of Cooled Spray Inserts for Particulate Reduction in a Heavy-Duty Engine
Authors: Klingbeil Adam , Tinar Tristen 
Published: December 2024

Abstract
Cooled spray technology has the potential to reduce particulate emissions in heavy-duty diesel engines by more than 50% while minimally impacting other emissions and performance parameters. However, the ideal design of these components is not known and there are a variety of parameters that could be varied to optimize performance including fuel passage diameter and length, fuel passage inlet and outlet geometry, surface finish and manufacturing materials.
In this study, we evaluate the effect of Cooled Spray geometry on engine performance. A focused study on fuel passage inlet shaping reveals a strong sensitivity, suggesting that chamfering the fuel passage inlet is critical for improved engine performance. In addition, the fuel passage diameter is varied between 2.2 and 2.8 mm to characterize the sensitivity of engine performance to the fuel passage diameter. At low load, the Cooled Spray inserts consistently show improving performance with smaller fuel passage diameter coupled together with chamfered fuel passage inlets for both EGR and non-EGR operation. At high load operation, the performance of the Cooled Spray inserts is notably worse with less consistent trends to fuel passage diameter and fuel passage inlet shaping. Furthermore, the performance trends at high load are different for EGR and non-EGR operation. This work shows that there is significant performance potential for this technology, but the relationship between geometry and ambient conditions needs to be understood and exploited for best overall performance.
An Experimental Comparison of Methanol Combustion Strategies: Spark Ignition Versus Compression Ignition
Authors: Gandolfo John , Lawler Benjamin , Gainey Brian 
Published: December 2024

Abstract
Methanol has garnered significant attention over the past few years due to its potential as a hydrogen carrier in a future green economy. As a result, it is a leading candidate to displace fossil fuels in the transportation sector. Although recent research efforts have been directed towards adopting the fuel in compression ignition engines, methanol is an ideal fuel for light-duty high compression ratio spark ignition engines due to its fast laminar flame speed, high auto-ignition resistance, and high cooling potential. In this work, methanol was combusted in a single-cylinder spark ignition engine with a compression ratio of 14.8 and compared to E10 (regular grade gasoline - 10% ethanol, 90% ethanol by volume), E75 (75% ethanol, 25% gasoline by volume), and hydrous ethanol (92% ethanol, 8% water by mass) at 6 bar IMEPn. Methanol achieved a net fuel conversion efficiency of 42.5% compared to 41.6% with hydrous ethanol, 39.5% with E75, and 36.2% with E10.
Next, the performance of the high compression ratio spark ignition engine was then compared to a methanol-fueled light-duty single-cylinder compression ignition engine. At loads of 6 bar and 10 bar IMEPn, the net fuel conversion efficiency of stoichiometric spark ignition was higher than lean mixing-controlled compression ignition by 2.6 and 3.3 percentage points, respectively. The net fuel conversion efficiency of mixing-controlled compression ignition was higher than spark ignition by 0.2 percentage points at a load of 16 bar IMEPn. The competitiveness of spark ignition with mixing-controlled compression ignition was due to the high thermodynamic penalty associated with injecting a high heat of vaporization fuel like methanol close to top dead center where heat from the working fluid is absorbed to evaporate the fuel rather than being converted to thermodynamic work. To remedy this, an advanced compression ignition strategy using premixed and partially premixed injections was demonstrated to provide the highest net fuel conversion efficiency across the tested combustion strategies by avoiding this thermodynamic penalty and taking full advantage of the lean and unthrottled nature of compression ignition.
Effect of Intrinsic Instabilities on Engine Performance for Hydrogen-Methane Blends
Authors: Nawaz Behlol , Cowart Jim , Das Shubhra Kanti , Nasim Md Nayer , Mack J. Hunter 
Published: December 2024

Abstract
Intrinsic instabilities cause wrinkling in laminar flames due to the mixture’s innate properties, regardless of chamber construction. While their effects are generally overshadowed in turbulent flames such as those observed in internal combustion engines, this is not the case for hydrogen (H2) flames. Blends of H2 and methane (CH4) have great potential to be used as low-carbon fuels, though they face several challenges associated with combustion behavior, material compatibility, and distribution infrastructure. Multiple equivalence ratios (Φ = 0.7, 0.77, and 1.0) and blends (0, 20, 30, and 50% H2 fuel fractions) were first studied in an optically accessible constant volume combustion chamber (CVCC) to determine the propensity for wrinkling among different equivalence ratio and blend combinations. These equivalence ratio and blend combinations were then tested in a spark ignition (SI) engine to investigate the performance of different intrinsic instability regimes of H2-CH4 blends. The results show that an increase in H2 fraction in the fuel increases the heat release and the peak in-cylinder pressure while reducing the burn duration. However, there was no indication that any of these metrics were affected by the flame wrinkling for the blends considered in this study.
Operation and Performance of a Monofueled Compression Ignition, Direct Injection, Natural Gas Heavy Duty Engine
Authors: White Tyler , Bonfochi Vinhaes Vinicius , Eggart Brian , Singh Ashish , Turcios Marco , Munshi Sandeep , Naber Jeffrey 
Published: December 2024

Abstract
The Compression Ignition of Directly Injected Natural Gas (CIDI NG) offers a potential 25% reduction in CO2 emissions due to its high hydrogen-to-carbon ratio compared to diesel, while achieving ultra-low PM formation with high efficiencies and load capability. The primary challenge of a CIDI NG engine is achieving suitable ignition temperatures, upwards of 1150K, and in-cylinder conditions required for the stable ignition and combustion of late cycle high pressure direct injection of the fuel over a wide operating range. This experimental study investigates CIDI NG combustion in a heavy-duty Single Cylinder Research Engine (SCRE). The SCRE uses a combination of ignition-enhancing technologies targeting the required conditions, including an increased compression ratio, intake charge heating, thermal barrier coatings, EGR, and NG pilot injection. Additionally, charge mixing is promoted through the refinement of the piston bowl geometry, resulting in improved efficiency and reduced soot formation. This study shows the effect of the implemented hardware technology (CR, Bowl Geometry, Thermal Barrier Coating) on the combustion at key operating conditions (low, medium, high load, high-efficiency operation, low emissions) of the NG CIDI engine. Stable combustion and engine operation were demonstrated over a wide load from 5.5 bar to a peak load of 25 bar IMEPg, and a maximum indicated thermal efficiency (ITE) of 48.8% at a load of 15.2 bar IMEPg was achieved. The work conducted with the single cylinder research engine shows that this operation is feasible and can become commercially available in the future.
Mixing and Warming Characterisation of Cryogenic Hydrogen Jets Through Proper Orthogonal Decomposition
Authors: Tretola Giovanni , Shen Li , Leach Felix , Vogiatzaki Konstantina 
Published: December 2024

Abstract
Hydrogen is being increasingly used as an alternative fuel for vehicles and aircraft propulsion. For long-distance transportation and large-scale energy storage, liquid hydrogen or cryo-compressed hydrogen with typical densities of 70 g/L, is more promising than warm compressed gaseous hydrogen. The use of cryogenic compressed hydrogen introduces new challenges for existing safety standards. In the event of potential leaks, the resulting jets are characterised by intense heat and mass transfer. Furthermore, given the storage pressure and leak diameters, these jets can acquire extremely high velocities, which, in combination with the ultra-low temperature prevailing, introduce considerable challenges to characterize the physics of complex cryogenic hydrogen jets. In this study, using a novel CFD framework specifically tailored to ultra cold dynamics, we analyse the warming and diffusion of a hydrogen cryogenic gas jet into atmospheric air. The simulated conditions are based on an experimental vertical jet. Stagnation conditions are characteristic of unintended leaks from pipe systems that connect cryogenic hydrogen storage tanks and could be encountered at a fuel cell refuelling station. Jets with pressure up to 5 bar and temperatures just above the saturation liquid temperature were examined. Comparisons are made to the centreline mass fraction and temperature decay rates. Satisfactory agreement with the measurements was found in terms of centreline mass fraction and temperature. To characterise the mixing and warming mechanisms of such cold jets, a principle component analysis (PCA) method, namely the proper orthogonal decomposition (POD) technique, is also performed on the simulated data sampled at a fixed domain but at different instants in time. The combined role of the mass and heat flux on heating the cold hydrogen jet is observed. The POD shows the role of turbulent fluctuations in warming the core of the jet. The heat flux observed in the outer plume instead is not captured by the low-order temporal fluctuations, which means that thermal diffusion is responsible for the warming in this region.
Investigation of Performance and Emissions of Premixed Combustion of Hydroprocessed Esters and Fatty Acids (HEFA) in a CRDI Research Engine With Methanol PFI
Authors: Soloiu Valentin , Willis James , Dillon Nicholas , Norton Coleman , Davis Zachary , Graham Tristan 
Published: December 2024

Abstract
An investigation of the performance and emissions of premixed combustion of a synthetic paraffinic kerosene sustainable aviation fuel (SAF) consisting of hydroprocessed esters and fatty acids (HEFA) was conducted using a CRDI research engine with ultra-low sulfur diesel (ULSD) as a reference. In a constant volume combustion chamber (CVCC), HEFA exhibited a shorter ignition delay, confirmed by its higher derived cetane number (DCN) at 58.6 compared to ULSD at 48. Further investigation was carried out at 5 bar indicated mean effective pressure (IMEP) with the addition of EGR to control combustion and mitigate NOx. Methanol, a low reactivity fuel, was port fuel injected (PFI) at 50% with HEFA (by mass) and ULSD to investigate its cooling effect on in-cylinder temperatures as a means of mitigating NOx.
Combustion pressure for HEFA was found to be greater than ULSD in most cases and occurred sooner. The apparent heat release rate (AHRR) was notably lower for HEFA than for ULSD in most cases, while the addition of methanol resulted in an increased duration of the low temperature heat release region for both HEFA and ULSD. With addition of EGR and PFI, several negative temperature coefficient regions were observed correlating with the pilot, primary, and tertiary direct injections.
HEFA saw more than a 10% reduction in NOx than ULSD in CDC. The addition of EGR resulted in further reduction of NOx compared to ULSD at equal operating points. Implementing EGR and 50% methanol PFI with HEFA reduced NOx emissions by over 70% compared to ULSD in CDC. In all studied cases, CO2 emissions for HEFA were slightly reduced compared to ULSD at matched operating parameters, while CO increased compared to ULSD. Lastly, both ULSD and HEFA achieved a combustion efficiency of 97% in CDC at 5bar IMEP. The combustion behavior of the studied HEFA in combination with the emissions reduction suggests potential suitability as a substitute for ULSD in some applications.
Investigation of the Performance and Properties Characterization of Hydro-Processed Esters & Fatty Acids (HEFA), FT Synthetic Paraffinic Kerosene (S8), F-24, and Jet-A
Authors: Soloiu Valentin , Norton Coleman G. , Davis Zachary W. , Graham Tristan , Strickland Mitchell , Rahman Mosfequr 
Published: December 2024

Abstract
In this study, Hydro-processed Esters & Fatty Acids (HEFA), FT synthetic paraffinic kerosene (S8), with F-24, & Jet-A as reference, were analyzed for their performance and fuel characteristics.
The spray characteristics of each fuel were evaluated utilizing a Malvern Spraytec He-Ne Laser. The Sauter Mean Diameter (SMD) was determined to be 14.24 μm, 17.22 μm, 18.40 μm, and 19.19 μm for HEFA, Jet-A, F-24, and S8 respectively. HEFA also displayed a spray droplet distribution (SDD) with a Relative Span Factor (RSF) of 2.17. Jet-A indicated an RSF of 2.49. S8 and F-24 displayed RSF values of 3.26 and 3.25.
The autoignition characteristics and combustion regions of the neat research fuels were analyzed in a CVCC to determine the effect of Derived Cetane Number (DCN) on Ignition Delay (ID), and Low Temperature Heat Release (LTHR). HEFA was found to have a DCN of 58.58, which was comparable to S8’s DCN of 59.96. The DCN of HEFA displayed an 18.4% increase from conventional Jet-A which has a DCN of 49.47. In addition, HEFA demonstrated shorter ignition delay and combustion delay at 2.70 ms and 4.10 ms, which were 15.09% and 14.58% shorter than Jet-A. HEFA exhibited a similar behavior to S8 generating a LTHR region that lasted a duration of 1.08 ms, or 28.94% shorter than Jet-A. The shorter LTHR duration led to less overall net heat release during LTHR for HEFA compared to Jet-A.
The tribological properties of each fuel were tested for their friction and wear on a T-11 Pin on disk tribometer under ASTM standard G99-17. HEFA displayed favorable results in comparison to F-24, S8, and Jet-A due to its superior tribological properties. This is seen with HEFA having a friction force of 0.0903N and a wear rate of 0.678 mm3N∗m * 10−4. Jet-A showed similar signs of friction and wear with results of 0.0926N and 0.82752 mm3N∗m * 10−4. F-24 and S8 were the worst out of the four fuels tested showing a friction force and wear rate of 0.0916N and 0.0945N and a wear rate of 1.19 mm3N∗m * 10−4 and 0.0932 mm3N∗m * 10−4 respectively.