Novel Ignition Approaches for Improved Hydrogen Ignition

The first study examined H₂ double injection ignition with varying dwell times. Experiments utilized a constant-volume combustion chamber (CVCC) with optical access, replicating compression-ignition engine conditions. Baseline environment: 23.8kg/m³ gas density, 21vol.% O₂, 1000K core temperature. Analysis methods: high-speed schlieren imaging, pressure trace analysis, jet mixing modeling, and constant-pressure homogeneous reactor (CHR) simulations. At 1000K, the 1st injection advanced 2nd injection ignition delay, reducing it from 9.66ms (single-injection) to 0.62ms relative to its start of injection, depending on dwell time. The shortest dwell time (1ms) reduced ignition events due to closely spaced injection interactions, while longer dwell times enabled robust ignition. CHR simulations revealed elevated local temperatures and flame intermediates from 1st injection influenced 2nd ignition processes. Temperature variations studies showed 1030K trends aligned with baseline, while 970K showed no ignition using identical schedules. Increasing the 1st injection quantity and extending the dwell time resolved this, demonstrating the strategy's sensitivity to ambient conditions. Findings highlight double injection potential for robust H₂ ignition in compression-ignition engines while emphasizing optimized injection parameters for specific operating conditions. The second study examined single H₂ jet ignition characteristics when interacting with Pt-coated rods under engine-like conditions (23.8kg/m³ gas density, 21vol.% O₂, 1000K core temperature). Experiments utilized a CVCC and a novel electromechanical device enabling Pt-coated catalyst rod insertion into the chamber for testing. At 1000K, average ignition delay for hydrogen jets interacting with Pt-coated rods was 4.13ms, significantly shorter than 9.02ms for H₂ free jets and 11.3ms when interacting with uncoated rods. At lower ambient temperatures (970K & 930 K), ignition occurred with Pt-coated rods (4.23ms and 6.25ms respectively), while H₂ free jets showed no ignition. Repeat tests with three additional Pt-coated rods showed measurable ignition delay reduction in only two rods, and only during isolated runs. Potential causes include catalyst degradation, manufacturing variability, and surface condition changes. These findings highlight both the potential and reliability challenges of Pt-assisted catalytic ignition in high-pressure H₂ direct injection applications.

Grantor dc:publisher

UNSW, Sydney

Year dc:date

2025

Author dc:creator

• Lin, Yijun

• Hydrogen
• Constant-volume combustion chamber
• Direct injection
• Multiple injection
• Hydrogen ignition
• Combustion
• Platinum
• Catalyst
• Engine
• Internal combustion rngine
• Fuel technology
• Renewable eneregy
• anzsrc-for: 4017 Mechanical engineering

Statement dc:rights

• open access
• CC BY 4.0
• free_to_read

Licence

• https://purl.org/coar/access_right/c_abf2
• https://creativecommons.org/licenses/by/4.0/

Language dc:language

en

Identifier

https://doi.org/10.26190/unsworks/31891

OAI identifier oai:identifier

oai:unsworks.library.unsw.edu.au:1959.4/106622