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This study explores the potential for ethanol use in the DI-HCRI (direct-injection homogeneous-combustion radical-ignition) diesel engine with its periphery-mounted secondary radical-generation chambers (mini-chambers). The aim of this simulation study is to determine whether HCRI alone can extend the lean burn region of this four-stroke ethanol engine to include low NOx operations at normal diesel compression ratios. The simulation employs a highly modified variant of an earlier single-phase full-kinetics formulation and a new chemical-kinetics mechanism with 57 species and 371 reactions. The fuel is injected in the liquid phase within both of the separate-but-connected open systems representing the main and mini chambers. Thus a droplet spray model is included in this full chemical-kinetics formulation to account for the vaporization and mixing of the liquid fuel in both chambers.

This paper examines the use of radial ignition (RI) at much lower than normal diesel compression ratios (CR's) in a novel direct-injection (DI) diesel rotary-combustion engine (RCE). Unique to this engine are periphery mounted secondary radical generation chambers (mini-chambers) capable of controlling the rates of radical generation. For this preliminary study the engine is operated on hydrogen under conditions conducive to homogeneous combustion RI (HCRI). One goal at the lower CR's normally needed in rotary-engine operations (<10:1) is to see whether HCRI alone can substantially extend the lean burn region of this rotary diesel engine with hydrogen as fuel. The ultimate aim is to enable high-power density operations with both low NOx emissions and low heat rejection. With these ends in mind a detailed examination is made (via simulation) of the effects of internally generated “radicals” on the combustion chemical-kinetics of this engine.

This study numerically examines the effects of select “radical species” on the hypergolic combustion of methanol fuel in a direct-injection (DI) naturally aspirated diesel engine at reduced compression ratios. These select radicals are generated via a set of micro-chambers (Figure 1) strategically placed within the piston at a location adjacent to the combustion bowl. Investigated are the effects of these radical species on the chemical-kinetics of main chamber autoignition. Also studied is the subsequent interactive radical generation processes and radical frozen equilibrium in both the micro and main chambers. In this new four-stroke numerical simulation, two open systems continuously interact, passing energy and chemical species between one another (through connecting vents) and with the manifold (via valves), while attempting to equalize pressure differences. The fuel is injected in such a way that the methanol enters the cylinder in a super-critical gas state and remains gaseous.

This study examines the novel use of a strong presence of radical ignition (RI) species to augment flame front propagation in a two-stroke spark ignition (SI) engine. Periphery mounted secondary chambers enable the generation of these RI species in one cycle for use in the next cycle. These chambers are outfitted to enable fuel-insertion and rapid heat addition. The new technology examined in the study employs the chemistry of homogeneous combustion radical ignition (HCRI) for the RI species enhancement of pre-mixed charge (PC) SI. The aim is to see if this chemistry can increase the lean burn threshold of this 2-stroke engine with natural gas (NG). The analysis uses experimental data together with a full chemical-kinetics simulation formulation that also accounts for thermo-chemical and hydro-dynamic exchanges that are both between the chambers and with the environment. The mechanism for the chemical kinetics consists of 97 chemical reactions involving 33 species.