Development of an Indicating Analysis and comparison with Multizone combustion diagnostics in a H2 DI ICE

As it is well known, the attention to sustainable mobility has increased significantly in these years, resulting in a challenging period for the transport sector. The EU Commission is facing the energetic transition adopting the resolution “Fit for 55”, which mandates a 55% reduction by 2030 of the Green House Gases (GHG) emissions (compared to 1990), moving towards Carbon Neutrality by 2050. To meet these targets, in addition to battery electric vehicles, hydrogen represents a fundamental pillar in the transportation, both for Fuel Cells and Internal Combustion Engines. Hydrogen Internal Combustion Engine (H2 ICE) constitutes one of the best technologies due to its zero CO2 tailpipe emissions and its minimal criteria pollutant: extremely low HC, CO and PM engine-out emissions coming only from lubricant oil consumption and low NOx stemming from lean combustion. The high-speed flame propagation, the high knock resistance and the ability to burn also at high dilution levels makes the hydrogen a very promising fuel for ICE application; on the other hand, it has also a low density which reduces the volumetric efficiency on Port Fuel Injection (PFI) applications. In order to reduce such drawback on volumetric efficiency and the risk of combustion anomalies related to excessive premixing and oil contamination, Direct Injection (DI) technology is being investigated. The key to obtain good results in terms of power, efficiency and emissions comes through the study of the hydrogen combustion in order to control the fuel properties at best. In this framework, the aim of this M.Sc. Thesis is the study, by means of different tools, of a pressure-based Diagnostics of combustion in a hydrogen fuelled engine with DI. The first part of this work is devoted to the development of an Indicating Analysis tool of the hydrogen combustion and the associated study of the Cycle-by-Cycle Variability using a Python code. The tool starts with a Single Zone Heat Release Analysis and then performs a Dual Zone Analysis. The experimental input data of the tool come from a H2-DI Single Cylinder Engine 0.5 L. Beginning from some outputs of this analysis (NHRR, Xb, COVimep), it is possible to calculate other relevant combustion parameters like Start of Injection (SOI), End of Injection (EOI), Start of Combustion (SOC), End of Combustion (EOC) following different methodologies (dedicated functions are defined for this purpose). Furthermore, a statistical analysis is performed to find the distributions/trends of the main combustion parameters. An optimizer is also included in the script to find the best Wiebe coefficients that fit the Mass fraction burned (MFB) experimental curves. The tool is completely customized to hydrogen combustion: all the outcomes are the results of implementing the thermochemical properties of all the species involved in the combustion (adopting the JANAF tables). The second part of this work is focused on the investigation of the results of a Multizone Burning Rate Analysis software developed by the DENERG (Politecnico di Torino) research group PoliTo-Engine Research Center. A comparative analysis is performed among the results of the two different tools. The Multizone is also capable of calculating additional combustion metrics as the speed of flame propagation and the NOx emission formation. One of the most interesting findings is the correlation between the Woschni coefficients (C0, C2) and the COVimep of the different engine points examined.