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Ethanol fuelled homogenous charge compression ignition engine offers a better alternative to tackle the problems of achieving higher engine efficiency and lower emissions using renewable fuel. Present study computationally investigates the HCCI operating range of ethanol at different compression ratios by varying inlet air temperature and engine speed using stochastic reactor model. A newly developed reduced ethanol oxidation mechanism with NO x having 47 species and 272 reactions is used for simulation. HCCI operating range for compression ratios 17, 19 and 21 are investigated and found to be increasing with compression ratio. Simulations are conducted for engine speeds ranging from 1000 to 3000 rpm at different intake temperatures (range 365–465 K). Parametric study of combustion and emission characteristics is conducted and engine maps are developed at most efficient inlet temperatures. HCCI operating range is defined using combustion efficiency (>85%) and maximum pressure rise rate (<5 MPa/ms). In HCCI operating range, higher efficiency is found at higher engine loads and lower engine speeds. Emission characteristics of species (NO x , N 2 O, CO, CH 4 , C 2 H 4 , C 2 H 6 , CH 3 CHO, and HCHO) found in significant amount is also analysed for ethanol fulled HCCI engine. Emission maps for different species are presented and discussed for wide range of speed and load conditions. Some of unregulated species such as aldehydes are emitted in significantly higher quantities from ethanol fuelled HCCI engine at higher load and speed conditions. [ABSTRACT FROM AUTHOR]

Ethanol is considered a potential biofuel for internal combustion engines. In this study, homogeneous charge compression ignition (HCCI) simulations of ethanol engine experiments were performed using stochastic reactor model (SRM). Detailed ethanol oxidation mechanism is developed by including NO x reaction in existing detailed oxidation mechanism with 57 species and 383 reactions. Detailed ethanol mechanism with NO x used in this study contains 76 species and 495 reactions. This mechanism was reduced by direct relation graph (DRG) method, which was validated with the experimental results. Existing Lu’s 40-species skeletal mechanism with NO formation were also compared with detailed and reduced mechanisms for predicting maximum cylinder pressure, maximum heat release rate and crank angle position of maximum cylinder pressure in HCCI engine. Reduced mechanism developed in this study exhibited the best resemblance with the experimental data. This reduced mechanism was also validated by measured engine cylinder pressure curves and measured ignition delays in constant volume reactors. The results showed that reduced mechanism is capable of predicting HCCI engine performance parameters with sufficient accuracy. Sensitivity analysis was conducted to determine the influential reactions in ethanol oxidation. Results also show that detailed and reduced mechanism was able to predict NO x emission in good agreement with the corresponding experimental data. [ABSTRACT FROM AUTHOR]