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In the present work, the in-cylinder tumble/swirl flow and its effect on the homogeneity, turbulence, and combustion of methane are investigated in a canted valve engine using ANSYS. The study is focused on the impact of initial swirl and tumble on the charge preparation, turbulent kinetic energy, and combustion of methane. The flow simulation was performed in ANSYS using hybrid mesh for cold flow simulation to study the tumble/swirl flow variation. For combustion simulation, a 2D axisymmetric model was used with an initial swirl and tumble ratio for studying the effect on premixed combustion. The flow simulation was performed for suction and compression to see the variation in the swirl and tumble with crank position and engine speed. The combustion simulation was performed only for compression and power stroke to save the computation time. The results depict that the flow inside the cylinder plays a significant role in the preparation of a homogeneous charge.

Homogeneous charge compression ignition (HCCI) engines are attracting attention as next-generation internal combustion engines mainly because of very low NOx and PM emission potential and excellent thermal efficiency. Particulate emissions from HCCI engines have been usually considered negligible however recent studies suggest that PM number emissions from HCCI engines cannot be neglected. This study is therefore conducted on a modified four cylinder diesel engine to investigate this aspect of HCCI technology. One cylinder of the engine is modified to operate in HCCI mode for the experiments and port fuel injection technique is used for preparing homogenous charge in this cylinder. Experiments are conducted at 1200 and 2400 rpm engine speeds using gasoline, ethanol, methanol and butanol fuels. A partial flow dilution tunnel was employed to measure the mass of the particulates emitted on a pre-conditioned filter paper.

The homogeneous charge compression ignition (HCCI) combustion process is capable of providing both high ‘diesel-like’ efficiencies and very low NOx and particulate emissions. However, among several technical challenges, controlling the combustion phasing, particularly during transients is a major issue, which must be resolved to exploit its commercial applications. This study is focused on the experimental investigations of behavior of combustion timing and other combustion parameters during startup and load transients. The study is conducted on a gasoline fuelled HCCI engine by varying intake air temperature and air-fuel ratio at different engine speeds. Port fuel injection technique is used for preparing homogeneous mixture of gasoline and air. For fueling startup transient test, fuel injection was turned off, and the engine was motored for several minutes until the fire-deck, intake and exhaust temperatures stabilized.

In the present study, experiments of reactivity control compression ignition (RCCI) combustion mode is performed on a single cylinder automotive diesel engine with development ECU (electronic control unit). For achieving RCCI combustion mode, low reactivity fuel (i.e., gasoline/methanol) is injected into the intake manifold, and high reactivity fuel (i.e., diesel) is directly injected into the engine cylinder. Mass of fuel injection per cycle and their injection events are controlled using ECU. This study presents the experimental investigation on the effect of high reactivity fuel injection timings on peak pressure rise rate (PPRR) and combustion stability in RCCI engine. The combustion parameters, i.e., PPRR, indicated mean effective pressure (IMEP) and total heat release (THR) are calculated from the in-cylinder pressure measurement data. In-cylinder pressure is measured using a piezoelectric pressure transducer installed on the engine cylinder head.

Research in the utilization of hydrogen and syngas has significantly increased due to their clean-burning properties and the prospect of production from several renewable resources. Homogeneous charge compression ignition (HCCI) engine is low-temperature combustion (LTC) concept which combines the best features of conventional spark-ignition (SI) and compression-ignition (CI) engines. HCCI combustion engine has shown the potential for higher efficiency and ultralow NOx and soot emissions. In this study, syngas fueled HCCI combustion is simulated using stochastic reactor model (SRM) with a detailed chemical kinetic mechanism (32 species and 173 reactions). Detailed syngas oxidation mechanism included NOx reactions also. In SRM models physical parameters are described by a probability density function (PDF). These parameters does not vary within the combustion chamber, and thus the spatial distribution (due to local inhomogeneity’s) of the charge is represented in terms of a PDF.

Ethanol fuelled homogenous charge compression ignition engine (HCCI) offers a better alternative to tackle the problems of achieving higher engine efficiency and lower emissions. Numerical simulations were carried out for a HCCI engine fueled with ethanol by stochastic reactor model using newly developed reduced ethanol oxidation mechanism consists of 47 species and 272 reactions. Reduced mechanism used in this study is validated by measured engine cylinder pressure curves and measured ignition delays in constant volume reactors in the previous study. Simulations are conducted for engine speeds ranging from 1000 to 3000 rpm at different intake temperatures (range 365-465 K) by varying the air-fuel ratio. Parametric study for combustion and emission characteristics is conducted and engine maps are developed at most efficient inlet temperatures. The HCCI operating range is defined using combustion efficiency (>85%) and maximum pressure rise rate (<5 MPa/ms).