اثر حجم تولوئن بر احتراق و انتشار موتورهای دیزل
Abstract
1- Introduction
2- Numerical model
3- Validation of the numerical model
4- Results and discussion
5- Conclusion
References
Abstract
A computational fluid dynamics (CFD) simulation model has been established to study the effects of toluene content in surrogate fuel on combustion and emissions for a large two-stroke marine diesel engine. In order to find more accuracy simulation model, the effects of toluene physical parameters were researched. Meanwhile the paper suggests a multi-components mechanism as surrogate fuel of diesel. The results indicate that the toluene content in surrogate fuel has an important impact on performance of marine engine. The ignition delay times increases with an increase in toluene content. However, the nitrogen oxide and soot mass are increase. The combustion will be influenced when the physical parameters of toluene are used in liquid fuel mixture. The nitrogen oxide has a peak value when the toluene content is used in the liquid fuel mixture. However, it has little influence on the in-cylinder pressure. The liquid parameters have also effect on the accuracy of simulation model. The in-cylinder pressure and emissions are higher when n-tetradecane is used in the liquid fuel mixture. By comparing the key parameters determined from simulations and experiments, it is found that the n-tetradecane-toluene with 30% of toluene is applicable to use as surrogate fuel of diesel.
Introduction
The introduction and enforcement of stringent environmental regulations has made it necessary for engine manufacturers to produce marine diesel engines with lower exhaust emissions. According to the International Marine Organization Tier III regulations, nitrogen oxide (NOx) emissions need to be reduced from 14.4 g/kWh (Tier II regulations) to 3.4 g/kWh [1]. Various techniques have been developed over the years to produce marine diesel engines that fulfil this requirement such as exhaust gas recirculation (EGR), selective catalytic reduction (SCR) and humid air motors (HAMs) [2–4]. Numerical simulations are now widely used to simulate the performance and exhaust emissions of marine diesel engines with advances in computer technology and software. Compared with real-world testing, numerical simulations are used to investigate the performance and exhaust emissions of marine diesel engines over a wide range of conditions while reducing significant resources and time associated with conventional experimentation. Ji et al. [5] researched the effects of Miller cycle, exhaust gas recirculation and intake air humidification coupled with fuel injection strategies on the NOx emissions using CFD software CONVERGE. A CTC/SHELL model was used to simulate auto-ignition of fuel. The surrogate fuel and combustion model were also used by Jiang et al. to research the effects of multiple-Injection coupled with EGR on combustion and NOx emissions in a marine diesel engine [6]. Zhou et al. [7] investigated the effect of injection direction and exhaust valve close timing on performance and emissions for a slow speed marine engine. The multi-zone sub-model was selected in combustion model. Sigurdsson et al.