Development of cold start premixed compression ignition ammonia combustion engine for zero emission

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K04244
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 19020:Thermal engineering-related
• Research Institution: Sophia University
• Principal Investigator: Ichiyanagi Mitsuhisa 上智大学, 理工学部, 教授 (00584252)
• Co-Investigator(Kenkyū-buntansha): 鈴木 隆 上智大学, 理工学部, 教授 (20206494)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: 熱機関 / アンモニア燃焼

Outline of Final Research Achievements

To develop automotive engines that use ammonia as fuel, we carried out the followings. Ammonia has the shortcomings of a slow burning velocity and a high ignition temperature. For increasing the burning velocity, the engine with a sub-chamber was adopted and the gasoline was used as an auxiliary fuel. In addition, a high compression ratio engine and a preheater were used in order to raise the gas temperature. Through the three-dimensional numerical simulations, the experiments using a constant volume combustion chamber with a sub-chamber, and the experiments using an actual engine with a sub-chamber, it was found that both the use of a high compression ratio engine and the increase in intake air temperature are effective in increasing the ratio of ammonia quantity in the air-fuel mixture. However, it was also found that the increase in intake air temperature increases the combustion period and decreases the combustion efficiency and the indicated thermal efficiency.

Free Research Field

熱工学

Academic Significance and Societal Importance of the Research Achievements

アンモニアは，燃焼速度が遅いという特徴があるため，これまで発電用の燃料としての使用が主であった．本研究では，燃焼速度を上げる方法として，副燃焼室付きのエンジンを採用した．また，発火点が高く，ガス温度の上昇が必要であるという問題に対しては，高圧縮比のエンジンを採用することで，ある一定の成果が得られた．本研究では，アンモニアとガソリンの混焼実験に止まったが，吸気温度の上昇がアンモニア比率を上げられることがわかった．ただし，燃焼期間が長くなるため，燃焼効率および図示熱効率は低下する．以上より，アンモニア燃料を用いた乗用車用エンジン実現に向けた課題がわかってきた．