Analysis on the operating performance of 5-kW class solid oxide fuel cell-internal combustion engine hybrid system using spark-assisted ignition

Jaehyun Kim, Yongtae Kim, Wonjae Choi, Kook Young Ahn, Han Ho Song

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30 Scopus citations


The objective of the proposed hybrid system is to increase the system efficiency by using the residual fuel of the anode off-gas from a solid oxide fuel cell in an internal combustion engine (ICE). In this study, a novel hybrid system using spark-assisted ignition (SAI) in an ICE operation is proposed. Since this is the first attempt of using a new combustion concept in a hybrid system, feasibility of SAI and its effect on the system operation are investigated in this study. To analyze the effect of the combustion on the system, the engine experiments on the SAI were conducted by changing the engine operating parameters, such as the intake temperature, equivalence ratio, and spark timing. For the system-level analysis, a zero-dimensional model for the fuel cell and the balance of plants was developed and validated. The results of the engine experiments were integrated directly with the system model. The performance of the hybrid system using SAI was analyzed from the energy and exergy perspectives. Under the operating conditions of this study, the anode off-gas combustion can be controlled stably (COV: 5–7%) through the SAI, even though the intake temperature is decreased to ~280 °C at the low compression ratio of 8.2. It leads to an increase in exergy efficiency of the engine to ~37%. Consequently, thermal self-sustainability is improved and the indicated efficiency of ~61.6% is achieved in the hybrid system. The SAI engine is responsible for ~14% of the system power and produces considerably low NOX emissions (<~3 ppm at 15% O2 on a dry basis).

Original languageEnglish
Article number114231
JournalApplied Energy
StatePublished - 15 Feb 2020

Bibliographical note

Funding Information:
This study was supported financially by the Korea Evaluation Institute of Industrial Technology (KEIT) in South Korea through the Institute of Advanced Machinery and Design (IAMD) in the Seoul National University , (Project Number: 10082569 ). Support was also provided by the Brain Korea 21 Plus Project in 2019. We are grateful for the support by MiCo Corporation. Appendix A

Publisher Copyright:
© 2019 Elsevier Ltd


  • Homogeneous charge compression ignition
  • Solid oxide fuel cell–internal combustion engine hybrid system
  • Spark ignition
  • Spark-assisted compression ignition
  • Synthesis gas combustion
  • System efficiency


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