Analysis of performance, emissions, and lubrication in a spark-ignition engine fueled with hydrogen gas mixtures.

Hydrogen is one of the main alternative fuels with the greatest potential to replace fossil fuels due to its renewable and environmentally friendly nature. Due to this, the present investigation aims to evaluate the combustion characteristics, performance parameters, emissions, and variations in the characteristics of the lubricating oil. The investigation was conducted in a spark-ignition engine fueled by gasoline and hydrogen gas. Four engine load conditions (25%, 50%, 75%, and 100%) and three hydrogen gas mass concentration conditions (3%, 6%, and 9%) were defined for the study. The investigation results allowed to demonstrate that the injection of hydrogen gas in the gasoline engine causes an increase of 3.2% and 4.0% in the maximum values of combustion pressure and heat release rates. Additionally, hydrogen causes a 2.9% increase in engine BTE. Hydrogen's more efficient combustion process allowed for reducing CO, HC, and smoke opacity emissions. However, hydrogen gas causes an additional increase of 14.5% and 30.4% in reducing the kinematic viscosity and the total base number of the lubricating oil. In addition, there was evidence of an increase in the concentration of wear debris, such as Fe and Cu, which implies higher rates of wear in the engine's internal components.

Energy Self-Sufficiency Conditions of Ethanol Autothermal Reforming: a Simulation Study

Abstract Natural gas steam reforming is commonly used for hydrogen production. However, research has shown that ethanol autothermal reforming can produce cleaner hydrogen gas efficiently. Despite this, there is a lack of studies on the energy self-sufficiency conditions of the ethanol autothermal reform. In this paper, we use simulations and the Response Surface Methodology (RSM) for the multivariate analysis of the energy self-sufficiency conditions in this process. First, we constructed and validated an industrial flowchart. After that, RSM allowed us to assess the process variables effects. The process variables studied were temperature (0 to 1000 ºC), pressure (20 to 30 bar), steam/ethanol ratio (2 to 5 mol/mol) and O2/ethanol ratio (0 to 1.5 mol/mol). We observe that the temperature and steam/ethanol ratio increase have a positive effect on hydrogen production. On the contrary, the O2/ethanol ratio increase has a negative effect, and the pressure increase is not statistically significant on hydrogen production. Therefore, the pressure was used at its minimum level (20 bar) while the temperature and the steam/ethanol ratio at its maximum levels (1000 ºC and 5 mol/mol). We also evaluated the energy consumption for the Autothermal Reactor (ATR). The reactor consumed 477.92 kJ/mol ethanol to produce 5.12 mol H2/mol ethanol when we use 1000 ºC, 20 bar, steam/ethanol 5 mol/mol, and O2/ethanol 0 mol/mol. ATR's energy self-sufficiency is achieved by using 1000 ºC, 20 bar, steam/ethanol 5 mol/mol, and O2/ethanol 0.86 mol/mol. In these conditions, 3.95 mol H2/mol ethanol is produced with 0 kJ/mol ethanol.