Development of Low-Pressure Direct Injection Hydrogen Engine Based on Numerical Analysis of Mixture Formation Characteristics by LES

Nobuhiro Shimmura (Tokyo City University/Kawasaki Heavy Industries)･Kotaro Hata (Tokyo City University)･Masakuni Oikawa (Tokyo City University/HEET)･Sekai Miyamoto (Kawasaki Heavy Industries)･Yuji Mihara (Tokyo City University/HEET)･Yasuo Takagi (Tokyo City University)

In direct injection hydrogen engine, the air-hydrogen mixture formation would be drastically changed by reducing the fuel injection pressure, and this mixture state has a great influence on the engine performance such as thermal efficiency and NOx emissions. In this study, factors that deteriorate the performance are identified and countermeasures for the improvement of the mixture state are examined by using large eddy simulation (LES), which enable to predict the unsteady mixture formation process accurately. The simulation results are compared with the actual engine test results in the same operating conditions.

Effect of Fuel Jet Specifications on Engine Performance in Lowered Injection Pressure in Direct Injection Hydrogen Engines

Kotaro Hata (Tokyo City University)･Nobuhiro Shimmura (Tokyo City University/Kawasaki Heavy Industries)･Masakuni Oikawa (Tokyo City University/HEET)･Sekai Miyamoto (Kawasaki Heavy Industries)･Yuji Mihara (Tokyo City University/HEET)･Yasuo Takagi (Tokyo City University)

In a direct hydrogen injection engine, the reduction of hydrogen supply pressure from 10 MPa to 3 MPa revealed an observable increase in NOx emission concentrations. To address this issue, the Design of Experiments method was employed to identify optimized nozzle specifications. Implementing these refined nozzle specifications resulted in the simultaneous achievement of high thermal efficiency and NOx emission concentrations below several tens of ppm.

Influences of Argon Fraction on Characteristics of H2/O2/Ar Premixed Flames

Tatsushi Nagai･Yuichi Shirayama･Mizuki Sakuma･Ekenechukwu C. Okafor･Toshiaki Kitagawa (Kyushu University)

Influences of argon fraction on the characteristics of H2/O2/Ar laminar and turbulent premixed flames were investigated by the experiments using a constant volume combustion bomb. Experiments were carried out varying the argon fraction at the equivalence ratio of 1.0. The characteristics of flames such as laminar and turbulent burning velocities were obtained.

Examining Fuel Consumption Performance of Hydrogen-Fueled Heavy Duty Vehicle on Demonstration

Kota Takanohashi･Kaname Naganuma (Kanazawa Institute of Technology)･Tadashi Enomoto･Takuya Yamaura (Flatfield)･Akemi Ito (Tokyo City University)･Yosuke Wakaki (Hokusan)･Jun Yamashita (Tonami Transportation)･Yuto Ihara (Waseda University)

Heavy duty vehicle with hydrogen fueled ICE is being tested for the purpose of evaluating the practicality, environmental friendliness and economic efficiency. In this study, the fuel consumption performance of the vehicle under real-world driving conditions are evaluated. As a results, effect of climate, driving characteristics, loaded weight and other conditions are analyzed and reported that the hydrogen fueled ICE performance is comparable to diesel heavy duty vehicles.

Optimizing Efficiency and NOx Emissions: Experimental Investigations of Hydrogen High-Pressure Direct Injection on a Heavy-Duty Single-Cylinder Research Engine

Robbert Willems･Xander Seykens･Erik Doosje･Cemil Bekdemir･Peter Van Gompel (TNO)

The H2-ICE emerges as a promising pathway for complying with upcoming heavy-duty CO₂ regulations. Several concepts are being investigated, where HPDI stands out for its excellent efficiency and performance. HPDI combustion is characterized by a hydrogen diffusion flame ignited by a diesel pilot. Significant NOx formation arising from diffusive combustion limits the maximum efficiency. In this paper, use of EGR and various fueling strategies are explored to optimize NOx emissions on a 1.8L single-cylinder engine. Although peak efficiency is constrained by NOx, it is shown that >50% indicated efficiency is possible with sufficiently low NOx toward compliance with future legislation.