Arkadiusz Jamrozik

This work experimentally evaluates the co-combustion of hydrogen and ammonia with diesel fuel in a dual-fuel compression ignition engine. The study examines how varying shares of H ₂ and NH ₃ affect combustion behavior, engine efficiency, and exhaust emissions, with ignition initiated by a pilot diesel injection. The alternative fuels accounted for 12%, 28%, 36%, and 42% of the total energy supplied to the engine. The results confirm that both hydrogen and ammonia can be successfully applied in dual-fuel diesel engine operation. Relative to neat diesel combustion, the addition of H ₂ or NH ₃ enhanced indicated thermal efficiency (ITE) and lowered specific emissions of NO (excluding 36% and 42% H ₂ share), unburned hydrocarbons, CO ₂ , and soot. Hydrogen supplementation reduced CO emissions in most cases (except at a 42% H ₂ share), whereas ammonia supplementation led to an increase in specific CO emissions. Moreover, the use of hydrogen and ammonia did not result in unacceptable increases in peak pressure rise (PPR) or the coefficient of variation of indicated mean effective pressure (COV _IMEP ), except at a 42% H ₂ share.

The gradual exhaustion of fossil fuel reserves, along with the adverse effects of their consumption on global climate, drives the need for research into alternative energy sources that can meet the growing demand in a sustainable and eco-friendly way. Among these, hydrogen stands out as one of the most promising options for the automotive sector, being the cleanest available fuel and capable of being produced from renewable resources. This paper reviews the existing literature on compression ignition engines operating in a dual-fuel configuration, where diesel serves as the ignition source and hydrogen is used to enhance the combustion process. The reviewed studies focus on engine systems with hydrogen injection into the intake manifold. The investigations analyzed the influence of hydrogen energy fraction on combustion characteristics, engine performance, combustion stability, and exhaust emissions in diesel/hydrogen dual-fuel engines operating under full or near-full-load conditions. The paper identifies the main challenges hindering the widespread and commercial application of hydrogen in diesel/hydrogen dual-fuel engines and discusses potential methods to overcome the existing barriers in this area.

The paper presents the results of research performed on an internal combustion diesel engine operating on a dual-fuel strategy. Fuels used during the study were diesel as a reference fuel, pure hydrogen, and ammonia as a hydrogen carrier. Fuel mixtures of diesel/hydrogen and diesel/ammonia were added to the engine, at energetic shares of 8, 12, 22, and 32% to maintain the constant engine load compared to the engine fueled with diesel. A comparison of the engine performance and the combustion process was made. Under the test conditions for all mixtures, the indication of the combustion pressure was made. The indication results were used to calculate engine performance parameters, such as IMEP, engine power, COVIMEP, and thermal efficiency. They were also used to describe the combustion process, including the determination of parameters like combustion stages, 50% MFB position, and HRR. The analysis of the results shows that adding hydrogen or ammonia as a main fuel causes a much faster combustion process compared to a diesel fuel engine. With an increase in energetic share, the combustion characteristic of the diesel/hydrogen engine shows two maxima in the HRR curve, besides 32% where there is only one peak. In contrast, for the diesel/ammonia engine, there is only one maximum, where an increase in the value of the kinetic combustion phase and the delay of ignition occur.

Piston engines used for powering automobiles as well as machinery and equipment have traditionally relied on petroleum-derived fuels. Subsequently, renewable fuels began to be used in an effort to reduce the combustion of hydrocarbon-based fuels and the associated greenhouse effect. Researchers are currently developing technologies aimed at eliminating fuels containing carbon in their molecular structure, which would effectively minimize the emission of carbon oxides into the atmosphere. Ammonia is considered a highly promising carbon-free fuel with broad applicability in energy systems. It serves as an excellent hydrogen carrier (NH₃), free from many of the storage and transportation limitations associated with pure hydrogen. Safety concerns regarding the storage and transport of hydrogen make ammonia an increasingly important fuel also due to its larger hydrogen storage capacity. This manuscript investigates the use of ammonia for powering a dual-fuel engine. The results indicate that the addition of ammonia improves engine performance; however, it may also lead to an increase in NO_x emissions. Due to the limitations of ammonia as a fuel, approximately 40% of the energy input must still be provided by diesel fuel to achieve optimal engine performance and acceptable NO_x emission levels. The presented research findings highlight the significant potential of NH₃ as an alternative fuel for compression-ignition engines. Proper control of the injection strategy or the adoption of alternative combustion systems may offer a promising approach to reducing greenhouse gas emissions while maintaining satisfactory engine performance parameters.

In the era of decarbonization driven by environmental concerns and stimulated by legislative measures such as Fit for 55, the industry and transportation sectors are increasingly replacing petroleum-based fuels with those derived from renewable sources. For many years, the share of these fuels in blends used to power compression ignition engines has been growing. The primary advantage of this fuel technology is the reduction of GHG emissions while maintaining comparable engine performance. However, these fuel blends also have drawbacks, including limited ability to form stable mixtures or the requirement for chemical stabilizers. The stability of these mixtures varies depending on the type of alcohol used, which limits the applicability of such fuels. This study focuses on evaluating the impact of eight types of alcohol fuels, including short-chain (methanol, ethanol, propanol) and long-chain alcohols (butanol, pentanol, hexanol, heptanol, and octanol), on the most critical operational parameters of an industrial engine and exhaust emissions. The engines being compared operated at a constant speed and under a constant load, either maximum or close to maximum. The study also evaluated the effect of alcohol content in the mixture on combustion process parameters such as peak cylinder pressure and heat release, which are the basis for parameterizing the engine’s combustion process. Determining ignition delay and combustion duration is fundamental for optimizing the engine’s thermal cycle. As the research results show, both the type of alcohol and its concentration in the mixture influence these parameters. Another parameter important from a usability perspective is engine stability, which was also considered. Engine performance evaluation also includes assessing emissions, particularly the impact of alcohol content on NO_x and soot emissions. Based on the analysis, it can be concluded that adding alcohol fuel to diesel in a CI engine increases ignition delay (up to 57%), p_max (by approximately 15–20%), HRR_max (by approximately 80%), and PPR_max (by approximately 70%). Most studies indicate a reduction in combustion duration with increasing alcohol content (by up to 50%). For simple alcohols, an increase in thermal efficiency (by approximately 15%) was observed, whereas for complex alcohols, a decrease (by approximately 10%) was noted. The addition of alcohol to diesel slightly worsens the stability of the CI engine. Most studies pointed to the positive impact of adding alcohol fuel to diesel on NOx emissions from the compression ignition engine, with the most significant reductions reaching approximately 50%. Increasing the alcohol fuel content in the diesel blend significantly reduced soot emissions from the CI engine (by up to approximately 90%).