||Diesel engine has better thermal efficiency than other engines, with the irreplaceable characteristics and advantages. Diesel engine is the first choice for the high torque output power machine, often used in heavy vehicles. However, the exhaust gas from diesel engine leads to a lot of serious pollution to the environment. To pursue the development of sustainability, it is not only to take into consideration of energy and economic, but also to pay much attention to the issues related to the exhaust pollution control from diesel engine.|
In this study, ANSYS FLUENT model is used as the research tool to explore the numerical simulation of two-dimensional of diesel engine pollutants, including gas velocity, exhaust gas temperature and pollutant emission concentration. According to different inlet speed, inlet temperature and other operation settings, pollutant emission concentration is analyzed and compared when C7H16 is used as fuel in this study. When it comes to the flow field analysis, the k-ε turbulence model is used to set up continuity equation, momentum equation and energy equation. Next, the reaction rate of C7H16, oxygen (O2), carbon monoxide (CO), carbon dioxide (CO2), nitric oxide (NO) and water vapor (H2O) are predicted by Arrenhnius equation.
Study one explores the result of changing the simulated inlet velocity when the air inlet temperature is fixed. The inlet temperature is 300K, with the simulation of inlet velocity changing from 20(m/s) to 60(m/s). The simulation results show: in exhaust gas, the concentration of CO reduces from 77.20×10-6 to 4.49×10-6 (kmol/m3), the concentration of CO2 reduces from 49.30×10-6 to 2.88×10-6 (kmol/m3), the concentration of NO reduces from 72.10×10-6 to 4.20×10-6 (kmol/m3) and the concentration of H2O decreased from 12.10×10-5 to 7.04×10-6 (kmol/m3). The research results can be seen that different inlet speed can affect the pollutant emission concentration. When the inlet speed is 60 (m/s), the pollutant emission concentration decreases significantly.
According to study one, study two explores the advanced result of changing the simulated air inlet temperature when the inlet velocity is fixed. The inlet velocity is 60(m/s), with the simulation of inlet temperature changing from 300K to 650K. The results show: in exhaust gas, the concentration of CO increases a little from 4.49×10-6 to 4.62×10-6 (kmol/m3), the concentration of CO2 increases a little from 2.88×10-6 to 2.96×10-6 (kmol/m3), the concentration of NO increases a little from 4.20×10-6 to 4.31×10-6 (kmol/m3) and the concentration of H2O increases a little from 7.04×10-6 to 7.23×10-6 (kmol/m3). Finally, the results show that the different inlet temperature has no significant impact on the concentration of pollutant emission.