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As a contribution to the research into HCCI engines which have a potential of achieving low fuel consumption with low particulate and low NOx emissions, a six zone simulation model coupled with the cycle simulation code AVL Boost was previously developed. The model uses comprehensive chemical kinetics and shows good agreement with experimental results. At the point of transition from the gas exchange process to the high pressure cycle, which is multi-zonal, the model assumes equal gas mixtures in all zones. Therefore, the model is suitable for perfectly homogeneous mixtures, and since it has no ability to receive fuel during compression, the mixture has to be prepared outside the cylinder. Further development of this model, which will be shown in this paper, includes the introduction of initial conditions with non-uniform mixtures and the possibility of receiving fuel during compression.

Today, the potential of HCCI engines, i.e., their high efficiency with low NO and particulate emissions, is very well known. Besides this potential, the problems that are related to HCCI engines, particularly the control, are also known issues. In order to be able to develop and assess the control strategies for HCCI engines, one needs models for the control development. In addition to mean value models crank-angle resolved control-oriented computer codes have also been developed lately (e.g., Boost RT). In these codes, complex 1D gas dynamics and complex combustion models are omitted, while the in-cylinder calculation is crank-angle resolved. Simple combustion models are variations of Vibe and the combustion defined by a table. Since the HCCI combustion is controlled by the state of the gas in the cylinder, parameters of Vibe functions depend on the factors that define this state.

This paper follows a cycle-simulation method for creating an engine performance map for an ethanol fueled boosted HCCI engine using a 1-dimensional engine model. Based on experimentally determined limits, the study defined operating conditions for the engine and performed a limited parameter sweep to determine the best efficiency case for each condition. The map is created using a 6-Zone HCCI combustion model coupled with a detailed chemical kinetic reaction mechanism for ethanol, and validated against engine data collected from a 1.9L 4-Cylinder VW TDI engine modified to operate in HCCI mode. The engine was mapped between engine speeds of 900 and 3000 rpm, 1 and 3 bar intake pressure, and 0.2 and 0.4 equivalence ratio, resulting in loads between idle and 14.0 bar BMEP. Analysis of a number of trends for this specific engine map are presented, such as efficiency trends, effects of combustion phasing, intake temperature, engine load, engine speed, and operating strategy.

Nowadays, the main potential of the HCCI engine, i.e. high efficiency with low NOx and soot emissions, is a well-known fact. Main limitations that prevent the commercial application of the HCCI engine are the control of combustion timing and low power density. Higher power density could be achieved by boosting the engine, but low exhaust temperatures associated with the HCCI combustion require a different approach when trying to achieve a boosted HCCI engine. This paper presents a numerical study on two boosting configurations that will enable high boost levels and high load, as a consequence, in the Ethanol fueled HCCI engine, in the engine speed range of 1000 - 4000 rpm. For the purposes of this study, a four-cylinder HCCI engine model has been made in the cycle-simulation software. The model includes the entire engine geometry and all elements necessary for representing the entire engine flow path.

It is a well-known fact that HCCI combustion offers the possibility of achieving high efficiency with low emissions, but with the challenges in combustion control and ability to adjust to changing environmental conditions. To resolve the aforementioned challenges, a pre-chamber induced homogeneous charge compression ignition (PC-HCCI) combustion mode was experimentally tested with aim of providing initial operating boundaries in terms of combustion stability and obtaining initial performance results. The single cylinder engine equipped with active pre-chamber and compression ratio (CR) of 17.5 was fueled by gasoline. The initial experiments were performed at the engine speed of 1600 rpm with intake air temperatures varied from 33°C to 100°C to verify the possibility of achieving the PC-HCCI combustion mode and to compare the achieved engine performance and emission results with both PCSI and pure HCCI combustion modes used as reference cases.

Homogeneous charge compression ignition (HCCI) in natural gas fueled engines is thought to achieve high efficiency and low NOx emissions. While automotive applications require various load and speed regions, the operation range of stationary cogeneration engines is narrower. Hence, HCCI operation is easier to reach and more applicable to comply with future emission standards. This study presents computationally investigations of the auto-ignition ranges of a stationary natural gas HCCI engine. Starting from a detailed 1D engine cycle simulation model, a reduced engine model was developed and coupled to chemical kinetics using AVL Boost. Compression ratio, air-fuel ratio, internal EGR rate (iEGR) and intake temperature were varied for three different speeds, namely 1200, 1700 and 2200 rpm. Each examination includes a full factorial design study of 375 configurations. In the first step, the combustion was calculated using the GRI-mechanism 3.0 and a single zone combustion model.

Advanced combustion concepts that rely on the lean-burn approach are a proven solution for increasing the efficiency and reducing the harmful emissions of SI engines. The pre-chamber spark ignited (PCSI) engines utilize high ignition energy of the multiple jets penetrating from the pre-chamber, to enable fast and stable combustion of lean mixture in the main chamber. The combustion is still governed by the flame propagation, so the dilution level and efficiency benefits are highly restricted by strong decrease of laminar flame speeds. Homogeneous charge compression ignition (HCCI) combustion allows a higher dilution level due to rapid chemically driven combustion, however the inability to directly control the ignition timing has proven to be a major setback in HCCI deployment.