Numerical Simulation Of The Influence Of Direct Air-cooled Island On The Environment

In northern China, direct air-cooled condenser, which has water-saving features, has been widely used. Direct air-cooled system provides cool air by axial fan, cooling steam turbine exhaust. By heat exchange between the air and steam, air-cooled island exhaust large amounts of hot air. Air flow and heat flow not only change the surrounding environment, but also impact the pollutant movement dispersion. So it is critical to study the influence of direct air-cooled island on the environment.This paper study the influence of direct air-cooled island on the environment using Fluent software. By establishing the model of air-cooled island and surrounding flow field, loading the function of speed and temperature distribution, in order to make the results more close to actual.First, this paper simulates the flow field and the distribution of temperature field around the air-cooled island in different wind speeds and temperature distributions. The results show that, when the speeds of coming wind are different, velocity distribution trend is basically the same, but the effects of blocking of the air-cooled island and building are different. At stable temperature stratification condition, rising air is suppressed, the height of maximum loss rate appears lower than the unstable stratification. In the vertical direction, the turbulent kinetic energy decreases with altitude, but in the air-cooled platform and its upper part will be a peak respectively. When the wind speed increases, the wind shear will increase. Wind shear at stable temperature stratification condition almost all larger than the unstable stratification condition. In the case of low wind speed, air-cooled island have large influence on the momentum flux. Even under stable temperature stratification condition, momentum flux of air-cooled island area is still larger than that in other areas of the unstable temperature stratification.Then analyze the pollutant concentration distribution. When the wind speed becomes large, there is conducive to the spread of pollutants. In unstable temperature stratification, pollutants more easily spread due to strong convection. In stable temperature stratification, the influence of air-cooled island on pollutants are far less than the influence of temperature stratification on pollutants.