【作者】

Raphael Ryser

【摘要】

该论文已在赫尔辛基举行的第28届CIMAC世界大会上发表，论文的版权归CIMAC所有。 In recent years fuel costs have become the predominant part of operating costs of low-speed engines. Therefore the thermodynamic cycle of uniflow scavenged 2-stroke engines needs to be optimized in the direction of highest efficiency. Additionally, within the boundaries implied by the powertrain layout there is some potential in changing cylinder geometries, power density and the corresponding turbocharging system for improved system efficiency. Application of variable exhaust valve timing, a state of the art technology, enables to set effective compression ratio according to the requirement to limit NOx and black smoke emissions. If in addition to this independent intake port opening and closing timing is introduced, the expansion stroke can be maximized without shortening the duration of gas exchange. Charge air pressure and supercharging efficiency need to be adapted to changing conditions in the gas exchange process to preserve sufficient scavenging. In this context the change from a 1-stage to a 2-stage turbocharging, ABBs Power2® package, offers a high potential due to the reserves in compression pressure ratio and system efficiency, which would also allow to increase mean effective pressure. In this paper the performance potential of variable intake port timing and especially its impacts on the layout and matching of the turbocharging system are presented. Furthermore the design parameters for the low- and highpressure stages of Power2® are discussed according to the results from parametric analysis.

【会议名称】

第28届CIMAC会议

【会议地点】

芬兰 赫尔辛基

【下载次数】

2

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