Methods of Increasing the BMEP (Power Output) for Natural Gas Spark Ignition Engines

981385

05/04/1998

Event
International Fuels & Lubricants Meeting & Exposition
Authors Abstract
Content
The present levels of the BMEP for natural gas fueled spark ignition engines, the BMEP of 1.0MPa for stoichiometric burn and 1.2MPa for lean burn, are lower than those of diesel engines. This paper discusses the reasons. The factors that limit the BMEP are mainly engine knocking and thermal loading such as exhaust temperature and boost pressure.
The Miller cycle and cooled EGR were applied to a turbo-charged, 324kW natural gas engine for co-generation. A lower compression ratio prevents engine knocking and a higher expansion ratio reduces the exhaust temperature in the Miller cycle. The EGR also improves the knock limit by reducing the exhaust temperature.
In the Otto cycle, the BMEP is limited by the EGR ratio (COV_IMEP) which is used to control the engine knocking and decrease the exhaust temperature, but in the Miller cycle with its high expansion ratio and low compression ratio, is limited by the boost pressure. The combination of the Miller cycle and EGR system demonstrates promising performance, substantially improving the BMEP to 1.7MPa under stoichiometric conditions compared to 1.0MPa by conventional engines. In this case, the following conditions were kept to ensure engine reliability.
No Caption Available
Meta TagsDetails
DOI
https://doi.org/10.4271/981385
Pages
11
Citation
Zhang, F., Okamoto, K., Morimoto, S., and Shoji, F., "Methods of Increasing the BMEP (Power Output) for Natural Gas Spark Ignition Engines," SAE Technical Paper 981385, 1998, https://doi.org/10.4271/981385.
Additional Details
Publisher
Published
May 4, 1998
Product Code
981385
Content Type
Technical Paper
Language
English