A reduced combustion kinetic model for the methanol-gasoline blended fuels on SI engines.

A reduced combustion kinetic model for the methanol-gasoline blended fuels for SI engines was developed. Sensitivity analysis and rate constant variation methods were used to optimize the kinetic model. Flame propagation, shock-tube and jet-stirred reactor systems were modeled in CHEMKIN. The laminar flame speed, ignition delay time and change in concentrations of species were simulated using the reduced kinetic model. The simulation results of reduced chemical mechanism agreed well with the relevant experimental data published in the literature. The experimental investigations on engine bench were also carried out. The in-cylinder pressure and exhaust emissions were obtained by using a combustion analyzer and an FTIR(Fourier transform infrared spectroscopy) spectrometer. Meanwhile, an engine in-cylinder CFD model was established in AVL FIRE and was coupled with the proposed reduced chemical mechanism to simulate the combustion process of methanol-gasoline blends. The simulated combustion process showed good agreement with the engine experimental results and the predicted emissions were found to be in accordance with the FTIR results.

Experimental investigation on combustion and unregulated emission characteristics of butanol-isomer/gasoline blends

Effects of butanol isomers on characteristics of combustion and emission were studied on PFI SI engine. Experiments were operated under the condition of 3 and 5 bar brake mean effective pressure (BMEP) engine loads and different equivalence ratios (φ=0.83-1.25) with engine speed of 1200 r/min using blends made of 70 vol.% gasoline and 30 vol.% butanol isomers (N30, S30, I30 and T30). The results indicated that compared with gasoline, all butanol isomer blends have higher cylinder pressure. N30 has the highest and most advanced peak pressure, and T30 shows a higher brake specific fuel consumption (BSFC) and lower brake thermal efficiency (BTE). N30 presents a lower UHC emissions and I30 has slightly higher CO emissions than other blends. For unregulated emissions, compared with gasoline, butanol isomer blends have higher acetaldehyde, and N30 produces a higher emission of 1,3-butadiene than other blends. A reduction in benzene, toluene, ethylbenzene and xylene (BTEX) has been found with butanol isomer blends.

Numerical study of CNG engine combustion using CFD with detailed chemical kinetics

A three dimensional model which considers the effects of turbulence and detailed chemi cal kinetics is built to simulate the combustion process of engine fueled by compressed nature gas （CNG）. The model is accomplished by integrating CFD software KIVA3V and chemical kinetic soft- ware CHEMKINII. Meanwhile, a turbulence combustion model which is suitable for describing the reaction rate under the coupled simulation is developed to balance the effects of turbulence and de tailed chemical kinetics. To reduce the computation time, subsequent development of the simulation code is realized, which enables the simulation code to have the function of parallel computing and run on parallel computing facility based on message passing interface （MPI）. The coupled software is used to simulate the combustion process of spark ignition CNG engine. The results show that sim ulation data have a good consistency with experimental results and parallel computing has good effi ciency and accelerate ratio.

The Evaluation of Liquefied Petroleum Gas (LPG) Utilization as an Alternative Automobile Fuel in Nigeria

The utilization of liquefied petroleum gas (LPG) as an alternative automobile fuel in Nigeria was studied, focusing on varying different blend ratios of propane and butane as an alternative fuel in a single-cylinder, four-stroke, and spark ignition (SI) engine. Ricardo WAVE, 1-Dimensional engine simulator was used to model the internal combustion engine where the different blend ratios of propane and butane (P100, P90B10, P80B20, P70B30, P60B40 and P50B50) were tested and compared with a gasoline engine operating under same conditions. From the simulation results for the different LPG blends, there was no significant difference in the engine performance and emissions, but when compared with pure gasoline, it was observed that the LPG showed improved engine performance and lower emissions. The engine power output in using the blends was 25% higher compared to using gasoline;CO emission was 50% less, UHC was 20% less while NOx at low speed was significantly lower.

Performance Evaluation of Spark Ignited Engine Fueled with Gasoline-Ethanol-Methanol Blends

In this paper, experimental investigations are presented to assess the performance variations in a single cylinder spark ignited engine when run with three different gasoline-alcohol blends： （88% gasoline-12% methanol, 88% gasoline-12% ethanol and 88% gasoline-6% methanol-6% ethanol）. Additional tests are carried out with the basic gasoline fuel for comparison analysis and performance assessment. Engine performance is investigated under a variety of engine operating conditions. The results are presented in the domain of engine speed. In particular, the brake power of the engine is shown to be slightly increased. The brake thermal efficiency showed an increase compared with the basic gasoline engine. Similarly, it is shown that brake specific fuel consumption is enhanced compared with basic gasoline engine. The exhaust gas temperature showed a decrease compared with gasoline fuel which is preferable to reduce emissions. The alcohol additives are strongly recommended to enhance performance, increasing the mileage and reducing the emissions.

Evaporate prediction and compensation of intake port wall-wetting fuel film for spark ignition engines fueled with ethanol-gasoline blends

The fuel dynamic transfer process,including fuel injection,fuel film deposition and evaporation in the intake port,was analyzed for spark ignition(SI) engines with port fuel injection(PFI).The influence of wall-wetting fuel film,especially its evaporation rate,upon the air-fuel ratio of in-cylinder mixtures was also discussed.According to the similarity principle,Fick's law,the ideal gas equation and the Gilliland correlation,an evaporate prediction model of wall-wetting fuel film was set up and an evaporate prediction based dynamic fuel film compensator was designed.Through engine cold start tests,the wall-wetting temperature,which is the key input of the fuel film evaporate prediction model,was also modeled and predicted.Combined with the experimental data of the evaporation characteristics of ethanol-gasoline blends and engine calibration tests,all the parameters of the wall-wetting fuel film evaporate prediction model used in the fuel film compensator were identified.Square-wave disturbance tests of fuel injection showed that with the help of the fuel film compensator the response of the in-cylinder air-fuel ratio was significantly improved and the real air-fuel ratio always closely matched the expected ratio.The fuel film compensator was then integrated into the final air-fuel ratio controller,and the engine tests showed that the air-fuel ratio control error was less than 2% in steady-state conditions,and less than 4% in transient conditions.The fuel film compensator also showed good adaptability to different ethanol-gasoline blends.