Theoretical investigation of Miller cycle characteristics

Baek, Hyun-Min; Jiwoong, Lee; Jung, Kyun-Sik; Choi, Jae-Sung

doi:10.5916/jkosme.2017.41.6.507

Cited by 1 publication

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“…In addition, the Miller cycle reduces NOx emissions by reducing the compression and combustion peak temperatures. The Miller cycle is one of the best methods to satisfy IMO (International Maritime Organization) Tier III regulations and improve thermal efficiency [38][39][40][41][42]. Therefore, determining the intake-valve closing timing, called the Miller timing, is one of the most important processes in developing auxiliary gas engines for ships.…”

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confidence: 99%

A Theoretical Study on the Thermodynamic Cycle of Concept Engine with Miller Cycle

Noh

Lee

2021

Processes

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The Atkinson cycle, where expansion ratio is higher than the compression ratio, is one of the methods used to improve thermal efficiency of engines. Miller improved the Atkinson cycle by controlling the intake- or exhaust-valve closing timing, a technique which is called the Miller cycle. The Otto–Miller cycle can improve thermal efficiency and reduce NOx emission by reducing compression work; however, it must compensate for the compression pressure and maintain the intake air mass through an effective compression ratio or turbocharge. Hence, we performed thermodynamic cycle analysis with changes in the intake-valve closing timing for the Otto–Miller cycle and evaluated the engine performance and Miller timing through the resulting problems and solutions. When only the compression ratio was compensated, the theoretical thermal efficiency of the Otto–Miller cycle improved by approximately 18.8% compared to that of the Otto cycle. In terms of thermal efficiency, it is more advantageous to compensate only the compression ratio; however, when considering the output of the engine, it is advantageous to also compensate the boost pressure to maintain the intake air mass flow rate.

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