Hydrogen engine technology has been developed by researchers at the Korea Institute of Machinery and Materials (KIMM) and Hyundai-Kia Motor Company (HMC). This collaborative effort has resulted in the creation of a 2-litre class hydrogen engine capable of running entirely on hydrogen, marking a first in South Korea.
The joint research team, led by Principal Researcher Young Choi of KIMM’s Department of Mobility Power Research and Researcher Hong-gil Baek of HMC’s Zero-Carbon Engine Research Lab, has developed the “direct injection hydrogen engine.” This innovative engine injects hydrogen directly into the combustion chamber of an existing hybrid vehicle’s engine, utilizing a turbocharger to enhance performance. This approach not only ensures high thermal efficiency across all engine conditions but also allows for stable operation from ignition to maximum engine load.
Traditional hydrogen engines, known as “port injection engines,” mix hydrogen with air in the intake port before combustion. This method often leads to decreased air intake due to the gaseous state of hydrogen, resulting in lower fuel efficiency and the risk of backfire. However, the direct injection method employed by the KIMM and HMC team bypasses these issues by injecting high-pressure hydrogen directly into the combustion chamber. This technique resolves backfire problems, achieves ultra-lean combustion, and significantly boosts thermal efficiency.
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Young Choi, Principal Researcher at KIMM, highlighted the environmental benefits of this technology: “The newly developed hydrogen engine technology is an instantaneous and economical solution that can replace fossil fuels with carbon-free hydrogen fuels.”
The direct injection hydrogen engine cuts carbon dioxide and fine dust emissions by 99% and 90%, respectively, compared to traditional gasoline engines, aligning with the European Union’s stringent zero-emission standards. Furthermore, it emits less than 15 ppm of nitrogen oxides without needing an after-treatment system, achieving an impressive thermal efficiency of up to 40%.
The key to this breakthrough lies in the direct injection method, which uses high-pressure hydrogen fuel to overcome the limitations of port injection engines. The researchers injected hydrogen at over 30 bar directly into the combustion chamber, using a turbocharger to maintain performance. This method ensures that hydrogen does not occupy the intake air space, preventing backfire and optimizing fuel stratification and combustion.
This approach also allows for higher compression ratios and more effective fuel stratification, which leads to improved power performance and reduced harmful emissions. The ultra-lean combustion process further lowers combustion temperatures, resulting in minimal nitrogen oxide emissions.
The next steps for the research team involve rigorous testing to verify the engine’s durability and exploring its applications beyond passenger vehicles. Young Choi emphasized the broader potential of this technology: “Through collaboration with HMC, we will verify the durability of the engine and expand its application to commercial vehicles and electricity generation power units. Our continuous research and development of carbon-free fuel technologies will drive the realization of carbon neutrality.”
This development represents a significant milestone in the global race to develop hydrogen mobility technologies. By offering a viable alternative to fossil fuel-powered engines, the direct injection hydrogen engine developed by KIMM and HMC could play a crucial role in reducing greenhouse gas emissions and promoting sustainable transportation.
The research team’s work has been published in the journal Science Direct, providing a detailed account of the methodologies and findings that underpin this groundbreaking advancement.