Impacts of Future NO_x and CO Emissions on Regional Chemistry and Climate over Eastern China

A coupled chemical/dynamical model （SOCOL-SOlar Climate Ozone Links） is applied to study the impacts of future enhanced CO and NO_x emissions over eastern China on regional chemistry and climate. The result shows that the increase of CO and NOx emissions has significant effects on regional chemistry, including NOx, CO, O_3, and OH concentrations. During winter, the CO concentration is uniformly increased in the northern hemisphere by about 10 ppbv. During summer, the increase of CO has a regional distribution. The change in O_3 concentrations near eastern China has both strong seasonal and spatial variations. During winter, the surface O_3 concentrations decrease by about 2 ppbv, while during summer they increase by about 2 ppbv in eastern China. The changes of CO, NO_x, and O_3 induce important impacts on OH concentrations. The changes in chemistry, especially O_3, induce important effects on regional climate. The analysis suggests that during winter, the surface temperature decreases and air pressure increases in central-eastern China. The changes of temperature and pressure produce decreases in vertical velocity. We should mention that the model resolution is coarse, and the calculated concentrations are generally underestimated when they are compared to measured results. However, because this model is a coupled dynamical/chemical model, it can provide some useful insights regarding the climate impacts due to changes in air pollutant emissions.

Simulation Analysis of CO Concentration Distribution in Beijing Yuntong Tunnel

In this paper, the concentration distribution of CO emitted by motor vehicles in Beijing Yuntong Tunnel is simulated and analyzed based on Fluent numerical simulation software. Firstly, the physical model of tunnel geometry is established. Secondly, the suitable control equations and boundary conditions are selected to describe the diffusion distribution of pollutants in the tunnel. At the same time, the reliability of the model is verified according to the measured data, and the distribution law of CO concentration in the tunnel is observed through the simulation results. The tunnel is unorganized at the entrance of the tunnel. In the simulation results, the CO concentration at the entrance of the tunnel is far more than the CO unorganized emission limit in Beijing. The CO emission of the tunnel should be purified to prevent pollution of the urban environment.

The Effect of Swirl Intensity on the Flow Behavior and Combustion Characteristics of a Lean Propane-Air Flame

The effect of swirl number(Sn)on the flow behavior and combustion characteristics of a lean premixed propane FlameФ=0.5 in a swirl burner configuration was numerically verified in this study.Two-dimensional numerical simulations were performed using ANSYS-Fluent software.For turbulence closure,a standard K-εturbulence model was applied.The turbulence-chemistry interaction scheme was modeled using the Finite Rate-Eddy Dissipation hybrid model(FR/EDM)with a reduced three-step reaction mechanism.The P1 radiation model was used for the flame radiation inside the combustion chamber.Four different swirl numbers were selected(0,0.72,1.05,and 1.4)corresponding to different angles(0°,39°,50°,and 57.8°).The results show that the predicted model agrees very well with the experimental data,especially with respect to the axial and radial velocity and temperature profiles.An outer recirculation zone(ORZ)is present in the combustor corner at Sn=0 and an inner recirculation zone(IRZ)appears at the combustor centerline inlet at a critical Sn=0.72.When the Sn reaches an excessive value,the IRZ moves toward the premixing tube,leading to a flame flashback.The flame structure and its length are strongly affected by changes in the Sn as well as the formation of NOx and CO at the combustor exit.