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Technical Paper

Computational Optimization of Syngas/Diesel RCCI Combustion at Low Load in Different Engine Size

Syngas is considered to be a promising alternative fuel for the dual-fuel reactivity controlled compression ignition (RCCI) engine to reduce the fuel consumption and emissions. However, the optimal syngas compositions and fuel supply strategies in RCCI combustion are significantly affected by engine configurations, which have not been investigated yet. In this study, by integrating the KIVA-3V code and the non-dominated sort genetic algorithm II (NSGA-II), the optimizations for a 0.477 L single-cylinder engine with shallow/wide piston bowl (Engine A) and a 1.325 L single-cylinder engine with conventional omega-type piston (Engine B) under the syngas/diesel RCCI combustion were performed. The optimized operating parameters include the fuel-supply strategies, syngas compositions, and intake conditions. The results indicate that the fuel-supply strategy is flexible in Engine A due to the shallow/wide piston bowl and the relatively small cylinder bore.
Technical Paper

Numerical Investigation of the Potential of Late Intake Valve Closing (LIVC) Coupled with Double Diesel Direct-Injection Strategy for Meeting High Fuel Efficiency with Ultra-Low Emissions in a Heavy-Duty Reactivity Controlled Compression Ignition (RCCI) Engine at High Load

The potential of diesel/gasoline RCCI combustion coupled with late intake valve closing (LIVC) and double direct injection of diesel for meeting high fuel efficiency with ultra-low emissions was investigated in this study. The study was aiming at high load operation in a heavy-duty diesel engine. Based on the reactivity stratification of RCCI combustion, the employment of double injection of diesel fuel provided concentration stratification of the high-reactivity fuel, which is to further realize effective control of the combustion process. Meanwhile, late intake valve closing (LIVC) strategy is introduced to control the maximum in-cylinder pressure and nitrogen oxides (NOx) emissions.
Technical Paper

The Study of an Optimum Method for Inlet Port Performance in a D.I. Diesel Engine

A new concept of “synthetic performance coefficient of inlet port” in D.I. diesel engines has been proposed from a viewpoint of efficiency of energy conversion in this paper. It makes the performance of various kinds of inlet ports in D.I. diesel engines compared with each other. Based on the regression analysis of the experimental results, it is found that the synthetic performance coefficient of inlet port has a close linear relation to the engine performance, and it can be used as a criterion to optimize the design of inlet port in D.I. diesel engines.
Journal Article

Evaluation of Spray/Wall Interaction Models under the Conditions Related to Diesel HCCI Engines

Diesel homogeneous charge compression ignition (HCCI) engines with early injection can result in significant spray/wall impingement which seriously affects the fuel efficiency and emissions. In this paper, the spray/wall interaction models which are available in the literatures are reviewed, and the characteristics of modeling including spray impingement regime, splash threshold, mass fraction, size and velocity of the second droplets are summarized. Then three well developed spray/wall interaction models, O'Rourke and Amsden (OA) model, Bai and Gosman (BG) model and Han, Xu and Trigui (HXT) model, are implemented into KIVA-3V code, and validated by the experimental data from recent literatures under the conditions related to diesel HCCI engines. By comparing the spray pattern, droplet mass, size and velocity after the impingement, the thickness of the wall film and vapor distribution with the experimental data, the performance of these three models are evaluated.