Energy conversion efficiency and performance analysis of hydrogen-fueled hydraulic engine (HFHE) using integrated simulation

In response to the global concern for carbon emission reduction and the challenges posed by climate change, the efficient conversion of energy across different forms is essential for modern energy systems and power plants. Thus, a novel hydrogen-fueled hydraulic engine (HFHE) is proposed in this study, capable of directly converting hydrogen energy into hydraulic energy while simultaneously outputting both mechanical and hydraulic energy. An integrated HFHE model, which accounts for time-varying and nonlinear factors, is established by modeling the internal combustion engine and the integrated synchronous plunger pump using GT-Power and AMESim, respectively, with data exchange facilitated through Simulink. The results indicate that efficiency improvements in the HFHE are primarily concentrated in medium-speed conditions, and the regulation of mechanical and hydraulic energy distribution significantly influences system efficiency. With increasing hydraulic load pressure (HLP), efficiency improvements gradually rise, and the peak efficiency region shifts toward lower mechanical load conditions. A maximum system efficiency of 43.8% is achieved under an HLP of 8 MPa, a mechanical load of 38 N m, and a speed of 1600 rpm. Parameter analysis further reveals that speed exerts a significantly greater impact on system efficiency and output power compared to HLP and air-fuel ratio.