Hydrogen is a promising fuel for internal combustion engines, offering the
potential for efficient, environmentally friendly, and reliable operation. With
a large number of technical challenges, there is currently no mass production of
hydrogen-powered engines despite great efforts. One of the key challenges is the
complexity of optimizing hydrogen combustion and its control. Despite the
variety of proposed operation strategies, questions regarding their comparative
efficiency, interrelation, and mutual influence remain open, particularly in
turbocharged engines with direct multi-injection. To explore various hydrogen
operation strategies, a mathematical simulation of a turbocharged
hydrogen-powered engine was performed over its full range of loads and speeds.
This study employed a modified mathematical model based on Wiebe functions,
which describes the combustion of a premixed mixture in the flame front,
diffusion combustion, and relatively slow combustion occurring behind the flame
front, in lean mixture zones, and near-wall regions. The results revealed that
in hydrogen engines, the use of well-known mixture formation strategies in
combination with early direct injection, spark timing, and boost control
presents significant challenges. These challenges include an increased risk of
abnormal combustion, reduced maximum engine power, higher NOx emissions, and
increased mechanical stress on engine components. The study identified the
operating conditions under which these issues are most likely to occur. To
mitigate these problems and improve engine efficiency, the focus was placed on
implementing a late injection strategy in conjunction with dual injection (two
injections of hydrogen during a single engine cycle). A methodology for
selecting the optimal dual injection and ignition parameters was developed and
the engine power cycle under these strategies was simulated. The research
results showed that the proposed approach leads to an increase in engine power,
a lower probability of abnormal combustion, reduced peak cylinder pressures, and
decreased nitrogen oxide emissions.
