An Experimental Investigation of the Maximum Load Limit of Boosted HCCI Combustion in a Gasoline Engine with Negative Valve Overlap.

HCCI;Maximum Load Limit;Negative Valve Overlap;Experimental Investigation;Gasoline;Mechanical Engineering;Engineering;Mechanical Engineering

Klinkert, StefanLavoie, George A. ;

University of Michigan

关键词: HCCI;    Maximum Load Limit;    Negative Valve Overlap;    Experimental Investigation;    Gasoline;    Mechanical Engineering;    Engineering;    Mechanical Engineering;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/107167/klinkert_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Use of homogeneous charge compression ignition (HCCI) combustion mode in engines offers the potential to simultaneously achieve high efficiency and low emissions. Implementation and practical use of HCCI combustion, however, remain a challenge due to the limited operating load range. Most studies on high load extension of HCCI have been done on engines with conventional positive valve overlap (PVO) strategies, which use a heater to control intake temperature and adjust combustion timing. Although there has been work on engines employing a more practical negative valve overlap (NVO) strategy, which controls charge temperature by varying the retained amount of hot internal residual gas, most of these studies were confined to a limited boost pressure range and/ or did not explore and isolate the effects of individual thermo-physical parameters on combustion and the maximum load limit. This research work is unique in that a practical yet highly flexible NVO engine, allowing for independent control of intake boost pressure, charge temperature and composition, thermal/ compositional stratification (NVO) and exhaust back-pressure, was used to independently investigate the effects of these variables on burn duration and combustion phasing limits. Results showed that maximum achievable loads for the NVO engine were less than those obtained by previous workers on a boosted PVO engine due to less efficient breathing, less stable combustion, which limits the achievable combustion phasing retard, and lower maximum allowable peak cylinder pressure.This research provides new insights into how boost pressure and other operating parameters in a NVO HCCI engine impact the maximum attainable load and combustion phasing limits. The results suggest that the maximum load is more dependent on the combustion stability limit and overall engine constraints, such as maximum allowable peak cylinder pressure and limited cam-phasing authority, than on burn rates.