By building on mature internal combustion engine (ICE) hardware combined with dedicated hydrogen (H2) technology, the H2-ICE has excellent potential to accelerate CO2 reduction. H2-ICE concepts can therefore contribute to realizing the climate targets in an acceptable timeframe. In the landscape of H2-ICE combustion concepts, High Pressure Direct Injection (HPDI™) is an attractive option considering its high thermal efficiency, wide load range and its applicability to on-road as well as off-road heavy-duty equipment. Still, H2-HPDI is characterized by diffusion combustion, giving rise to significant NOx emissions. In this paper, the potential of H2-HPDI toward compliance with future emissions legislation is explored on a 1.8L single-cylinder research engine. With tests on multiple load-speed points, Exhaust Gas Recirculation (EGR) was shown to be an effective measure for reducing engine-out NOx, although at the cost of a few efficiency points.
The reduction of anthropogenic greenhouse gas emissions and ever stricter regulations on pollutant emissions in the transport sector require research and development of new, climate-friendly propulsion concepts. The use of renewable hydrogen as a fuel for internal combustion engines promises to provide a good solution especially for commercial vehicles. For optimum efficiency of the combustion process as efficient, hydrogen-specific engine components are required, which need to be tested on the test bench and analysed in simulation studies. This paper deals with the simulation-based investigation and optimisation of fuel injection in a 6-cylinder PFI commercial vehicle engine, which has been modified for hydrogen operation starting from a natural gas engine concept.
The global transportation industry is mandated to deliver significant reductions in Greenhouse Gas (GHG) emissions within the upcoming decades. The road freight sector in particular faces formidable challenges in terms of emission reduction, while maintaining/improving the performance of the current vehicles. In Europe this transition is being driven in part by specific CO2 legislation for heavy-duty vehicles (HDVs) and penalties for Original Equipment Manufacturers who miss these targets, while in the US these ambitions have been embedded within the EPA regulations. Europe currently has targets for CO2 reduction of 15% by 2025 and 30% by 2030 for new HDVs, likely increasing to 45% by 2030 and 90% by 2040. These targets have been set relative to the fleet average for the industry by truck category and are evaluated using the Vehicle Energy Consumption Calculation Tool (VECTO) to determine CO2 emissions for each unique vehicle configuration.
Climate change and the decarbonization process are challenges for our times. In this context, the transportation sector is undergoing significant changes and new scenarios in the future mobility are open. For light duty vehicles, electrification represents the most immediate and spreading solution; however, to promote the e-mobility expansion, technological improvements mainly related to the charging infrastructures are needed. This work aims at investigating the possibility to use a spark ignition engine fueled with bio-ethanol for off-grid electric vehicle charging station. The engine is a 8.7 liter turbocharged spark ignition engine, single point injection and develops a maximum rated power of about 230 kW at 1500 rpm. A 1-D numerical model was developed to evaluate the main performance in terms of brake power, efficiency, specific fuel consumption and NOx emissions at different spark advances and air-fuel ratio.
The objective of this study is to investigate the potential of a sustainable fuel composed of ethanol and lignin for marine engines. Lignin is the second most abundant biomass after cellulose, produced i.e. from the pulp-and-paper industries. Lignin has a higher heating value (HHV) of 23.2 – 25.6 MJ/kg but is difficult to exploit efficiently because it is a stable solid material and often ends up as waste. combining lignin and alcohol to a liquid fuel has a huge interest, and is mainly for marine engines as they are designed to tolerate a wide range of fuels. In this study, lignin-fuel with 44 wt% lignin and 50 wt% of ethanol was experimentally evaluated by using an extensively modified small-bore compression ignition (CI) engine. The technical challenges and approach to applying this kind of lignin-fuel to engines are presented.
Heavy duty truck engines are quite difficult to electrify, due to the large amount of energy required on-board, in order to achieve a range comparable to that of diesels. This paper considers a commercial 6-cylinder engine with a displacement of 12.8 L, developed in two different versions. As a standard diesel, the engine is able to deliver more than 420 kW at 1800 rpm, whereas in the CNG configuration the maximum power output is 330 kW at 1800 rpm. Maintaining the same combustion chamber design of the last version, a theoretical study is carried out in order to run the engine on Hydrogen, compressed at 700 bar. The study is based on GT-Power simulations, adopting a predictive combustion model, calibrated with experimental results. The study shows that the implementation of a combustion system running on lean mixtures of Hydrogen, permits to cancel the emissions of CO2, while maintaining the same power output of the CNG engine.
The passive pre-chamber is valued for its jet ignition and is widely used in the field of gasoline direct injection (GDI) for small passenger cars, which can improve the performance of lean combustion. However, the scavenging and ignition combustion stability of the engine at low speed is a shortcoming that has not been overcome. Simply changing the structural design to increase the fluidity of MC and PC may lead to a reduction in jet ignition performance, which in turn will affect engine dynamics. This investigation is based on a non-uniformly nozzles distributed passive pre-chamber, which is adjusted according to the working fluid exchange between PC and MC. The advantages and disadvantages of the ignition mode of PC and SI in the target engine speed range are compared through optical experiments on a small single cylinder GDI engine. The results show that with the increase of λ from 1.0 to 1.6, the promotion effect of PCJI on load performance gradually decreases.
To mitigate the NOx emissions from diesel engines, the adoption of exhaust gas recirculation (EGR) has gained widespread acceptance as a technology. Nonetheless, employing EGR has the drawback of elevating soot emissions. The use of hydrogen-enriched air with EGR in a diesel engine (dual-fuel operation), offers the potential to decrease in-cylinder soot formation while simultaneously reducing NOx emissions. The present study numerically investigates the effect of hydrogen energy share and engine load on the formation and emission of soot and NOx emission from hydrogen-diesel dual-fuel engine. The numerical investigation is performed using an n-heptane/H2 reduced reaction mechanism with a two-step soot model in ANSYS FORTE. To enhance the accuracy of predicting dual-fuel combustion in a hydrogen-diesel dual-fuel engine, a reduced n-heptane reaction mechanism is integrated with a hydrogen reaction mechanism using CHEMKIN.
Ammonia (NH3), a zero-carbon fuel, has great potential for internal combustion engine development. However, its high ignition energy, low laminar burning velocity, a narrow range of flammability limits, and high latent heat of vaporization are not conducive for engine application. This paper numerically investigates the feasibility of utilizing ammonia in a heavy-duty diesel engine, specifically through the method of low-pressure direct injection (LP-DI) of hydrogen to ignite ammonia combustion. The study compares the engine's combustion and emission performance by optimizing four critical parameters: excess air ratio, hydrogen blending ratio, ignition timing, and hydrogen injection timing. The results reveal that excessively high hydrogen blending ratios lead to an advanced combustion phase, resulting in a reduction in indicated thermal efficiency.
Engine knock is a major barrier to achieving higher engine efficiency by increasing the compression ratio of the engine. It is an abnormal event caused by the autoignition of air-fuel mixture ahead of the propagating flame front. A higher octane number fuel can be a good solution to reduce or eliminate the higher knock intensity and obtain better engine performance. Methanol is a promising alternative fuel, which has a higher octane number and can be produced from conventional and non-conventional energy resources to reduce pollutant emissions. This study compares the combustion characteristics of gasoline and methanol fuels in an optical spark-ignition engine using multiple spark plugs. The experiment was performed on a single-cylinder four-stroke optical engine. A customized metal liner equipped with four circumferential spark plugs was used to generate multiple flame kernels inside the combustion chamber.
A potential route to reduce CO2 emissions from heavy-duty trucks is to combine low-carbon fuels and vehicle electrification/hybridization. Hybridization offers the potential to downsize the engine. Although engine downsizing in the light-duty sector can offer significant fuel economy savings mainly due to increased part-load efficiency, its benefits and downsides in heavy-duty engines are less clear. As there has been limited published research in this area to date, there is a lack of a standardized engine downsizing procedure. This paper aims to use an experimentally validated one-dimensional phenomenological combustion model in a commercial engine simulation software GT-Power alongside turbocharger scaling methods to develop downsized engines from a baseline 6-cylinder (2.2 L/cyl, 26 kW/L) pilot-ignition, direct-injection natural gas engine.