Effect of Valve Timing and Excess Air Ratio on Torque in Hydrogen-Fueled Internal Combustion Engine for UAV

Cheolwoong Park, Wonah Park, Yongrae Kim, Young Choi and Byeungjun Lim
Additional contact information
Cheolwoong Park: Engine Research Team, Environmental System Research Division, Korea Institute of Machinery and Materials, Daejeon 34103, Korea
Wonah Park: Engine Research Team, Environmental System Research Division, Korea Institute of Machinery and Materials, Daejeon 34103, Korea
Yongrae Kim: Engine Research Team, Environmental System Research Division, Korea Institute of Machinery and Materials, Daejeon 34103, Korea
Young Choi: Engine Research Team, Environmental System Research Division, Korea Institute of Machinery and Materials, Daejeon 34103, Korea
Byeungjun Lim: Engine Component Technology Team, Aeropropulsion Division, Korea Aerospace Research Institute, Daejeon 34133, Korea

Energies, 2019, vol. 12, issue 5, 1-14

Abstract: In this study, in order to convert a 2.4 L reciprocating gasoline engine into a hydrogen engine an experimental device for supplying hydrogen fuel was installed. Additionally, an injector that is capable of supplying the hydrogen fuel was installed. The basic combustion characteristics, including torque, were investigated by driving the engine with a universal engine control unit. To achieve stable combustion and maximize output, the intake and exhaust valve opening times were changed and the excess air ratio of the mixture was controlled. The changes in the torque, excess air ratio, hydrogen fuel, and intake airflow rate, were compared under low engine speed and high load (wide open throttle) operating conditions without throttling. As the intake valve opening time advanced at a certain excess air ratio, the intake air amount and torque increased. When the opening time of the exhaust valve was retarded, the intake airflow rate and torque decreased. The torque and thermal efficiency decreased when the opening time of the intake and exhaust valve advanced excessively. The change of the mixture condition’s excess air ratio did not influence the tendency of the torque variation when the exhaust valve opening time and torque increased, and when the mixture became richer and the intake valve opening time was fixed. Under a condition that was more retarded than the 332 CAD condition, the torque decreased by about 2 Nm with the 5 CAD of intake valve opening time retards. The maximum torque of 138.1 Nm was obtained at an optimized intake and the exhaust valve opening time was 327 crank angle degree (CAD) and 161 CAD, respectively, when the excess air ratio was 1.14 and the backfire was suppressed. Backfire occurred because of the temperature increase in the combustion chamber rather than because of the change in the fuel distribution under the rich mixture condition, where the other combustion control factors were constantly fixed from a three-dimensional (3D) computational fluid dynamics (CFD) code simulation.

Keywords: hydrogen; port fuel injection engine; torque; backfire; excess air ratio; valve opening time (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2019
References: View complete reference list from CitEc
Citations: View citations in EconPapers (3)

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