Homogeneous charge compression ignition combustion stability improvement using a rapid ignition system

Abstract

When compared to traditional engines, homogeneous charge compression ignition has the potential to significantly reduce NO x raw emissions, while maintaining a high fuel efficiency. Homogeneous charge compression ignition is characterized by compression-induced autoignition of a lean homogeneous air–fuel mixture. Since homogeneous charge compression ignition does not utilize direct ignition control, it is strongly dependent on the state of the cylinder charge and can suffer from high cyclic variability. With spark-assisted compression ignition, it has been demonstrated that misfires can be reduced, while preserving the high thermal efficiency of homogeneous charge compression ignition as a result of the more favorable physical mixture properties due to dilution. However, spark-assisted compression ignition reduces the NO x benefits of homogeneous charge compression ignition, as it increases the local combustion temperatures. To merge the advantages of the homogeneous charge compression ignition and the spark-assisted compression ignition combustion processes, a field-programmable gate array for detailed simulation of the physical gas exchange is combined with a rapid spark system. The low latency and computational speed of the field-programmable gate array allows the simulation process to be implemented in real time. When combined with the rapid reaction time of the high-frequency current-based rapid ignition system, a feedforward controller based on the cylinder pressure or heat release is realized. The developed model-based controller determines if a spark is required to assist the homogeneous charge compression ignition combustion process. The use of the field-programmable gate array and rapid ignition system allows for the calculation of combustion properties and controller output within 0.1 °CA. This article presents the development and experimental validation of the developed controller on a single-cylinder research engine. The combustion stability has been significantly improved as reflected in an improved standard deviation of the indicated mean effective pressure and a reduction of the combustion phasing variations. Furthermore, compared to a traditional homogeneous charge compression ignition system, the hydrocarbon emissions can be reduced, while maintaining low NO x emissions.

Analysis of experimental results with an active pre-chamber ultra-lean burn SI engine

“…3 It achieves very low HC and NOx emissions while achieving high efficiency. Even though there are many developments ongoing to improve the control and the cycle to cycle variations, 4–7 these combustion processes still have a narrow range of stable operation.…”

Experimental investigation of the effect of temperature on ignition of modified kerosene

“…A possible solution to this problem is to modify the specification of fuel by decreasing the total sulphur content allowed. Various experimental methodologies are used for combustion and ignition studies such as constant volume bombs, rapid compression machines, [33][34][35][36][37] Jet-stirred reactors, 38,39 continuous flow reactors 40 and Spray ignition 41 and shock tubes. [41][42][43] Among the methods used to study the ignition of fuels, the shock tube has been a very effective tool and remains an important means of investigation because of improvements in the measurement techniques.…”

Analysis of ion current signal during negative valve overlap of HCCI combustion with high compression ratio

“…Most of these controllers work on a cycle-to-cycle base and use representative parameters of the previous combustion cycle like the combustion phasing, defined by the position where 50% of the fuel mass burned (MFB50), or the indicated mean effective pressure (IMEP). 8–10 More complex algorithms include additional parameters like fuel mass and temperature. 11,12 A first control approach using the ion current sensor and direct water injection has also been published by Zhu et al 13…”