Status and Prospects of Glow Plug-Assisted Ignition Technology for Methanol Engines: A Review

Methanol has attracted growing attention as a low-carbon alternative fuel for internal combustion engines. However, its low cetane number and high auto-ignition temperature pose significant challenges to achieving reliable ignition and efficient combustion in compression-ignition engines. To overcome these challenges, various advanced combustion strategies have been developed, among which glow plug-assisted ignition (GPAI) technology has emerged as an effective approach for initiating and sustaining methanol combustion under compression ignition conditions. This review systematically summarizes the recent advances in GPAI technology for methanol engines. The fundamental combustion strategies for methanol engines and the operating principles of GPAI are first introduced, followed by a comprehensive review of recent progress in GPAI methanol engines from the perspectives of engine performance, ignition characteristics, in-cylinder flame evolution, combustion behavior, and pollutant formation. This review highlights the critical role of the glow plug in promoting the formation of the initial ignition kernel and regulating subsequent combustion evolution in methanol engines. The existing literature demonstrates that GPAI technology can effectively facilitate methanol ignition and support high-efficiency combustion under compression ignition conditions. However, current research remains predominantly based on numerical simulations, while experimental investigations are relatively limited, particularly for large-bore engines. Overall, this review provides a comprehensive understanding of the ignition and combustion mechanisms of GPAI methanol engines and identifies key research needs to support their further development and practical application.