CFD Simulation of Pollutant Emission in a Natural Draft Dry Cooling Tower with Flue Gas Injection: Comparison between LES and RANS

Accurate prediction of pollutant dispersion is vital to the energy industry. This study investigated the Computational Fluid Dynamics (CFD) simulation of pollutant emission in a natural draft dry cooling tower (NDDCT) with flue gas injection. In order to predict the diffusion and distribution characteristics of the pollutant more accurately, Large Eddy Simulation (LES) was applied to predict the flow field and pollutant concentration field and compared with Reynolds Average Navier-Stokes (RANS) and Unsteady Reynolds Average Navier-Stokes (URANS). The relationship between pollutant concentration pulsation and velocity pulsation is emphatically analyzed. The results show that the flow field and concentration field simulated by RANS and URANS are very close, and the maximum value of LES is about 43 times that of RANS and URANS for the prediction of pollutant concentration in the inner shell of cooling tower. Pollutant concentration is closely related to local flow field velocity. RANS and URANS differ greatly from LES in flow field prediction, especially at the outlet and downwind of cooling tower. Compared with URANS, LES can simulate flow field pulsation with a smaller scale and higher frequency.

[1]  Rodney R. Saldanha,et al.  An Air Pollutant Emission Analysis of Brazilian Electricity Production Projections and Other Countries , 2019, Energies.

[2]  Yoshihide Tominaga,et al.  AIJ guidelines for practical applications of CFD to pedestrian wind environment around buildings , 2008 .

[3]  Bert Blocken,et al.  CFD simulation of near-field pollutant dispersion on a high-resolution grid : a case study by LES and RANS for a building group in downtown Montreal , 2011 .

[4]  John Kaiser Calautit,et al.  Comparison between evaporative cooling and a heat pipe assisted thermal loop for a commercial wind tower in hot and dry climatic conditions , 2013 .

[5]  Xiaoxiao Li,et al.  Performance enhancement for the natural draft dry cooling tower under crosswind condition by optimizing the water distribution , 2017 .

[6]  M. Ahmadi,et al.  Impacts of Traffic Tidal Flow on Pollutant Dispersion in a Non-Uniform Urban Street Canyon , 2018 .

[7]  Di Yang,et al.  Large-Eddy Simulation-Based Study of Effect of Swell-Induced Pitch Motion on Wake-Flow Statistics and Power Extraction of Offshore Wind Turbines , 2019, Energies.

[8]  Ryszard A. Białecki,et al.  3D CFD modeling of natural draft wet-cooling tower with flue gas injection , 2015 .

[9]  Yoshiaki Miyamoto,et al.  Thermal hydraulic study on a high-temperature gas–gas heat exchanger with helically coiled tube bundles , 1998 .

[10]  Michael Schatzmann,et al.  Flue gas discharge from cooling towers. Wind tunnel investigation of building downwash effects on ground-level concentrations , 1987 .

[11]  V. Aneja,et al.  Characterization of Particulate Matter (PM2.5 and PM10) Relating to a Coal Power Plant in the Boroughs of Springdale and Cheswick, PA , 2017 .

[12]  J. Fröhlich,et al.  Hybrid LES/RANS methods for the simulation of turbulent flows , 2008 .

[13]  P. Córdoba.  Status of Flue Gas Desulphurisation (FGD) systems from coal-fired power plants: Overview of the physic-chemical control processes of wet limestone FGDs , 2015 .

[14]  Chao Li,et al.  Structural Analysis of Large-Scale Vertical-Axis Wind Turbines, Part I: Wind Load Simulation , 2019, Energies.

[15]  J. Smagorinsky,et al.  GENERAL CIRCULATION EXPERIMENTS WITH THE PRIMITIVE EQUATIONS , 1963 .

[16]  Andy Chan,et al.  Numerical simulation of dispersion in urban street canyons with avenue-like tree plantings: Comparis , 2011 .

[17]  Yoshihide Tominaga,et al.  CFD modeling of pollution dispersion in a street canyon: Comparison between LES and RANS , 2011 .

[18]  Leonidas Ntziachristos,et al.  Real-World Measurement of Hybrid Buses’ Fuel Consumption and Pollutant Emissions in a Metropolitan Urban Road Network , 2018, Energies.

[19]  Lan Li,et al.  Effects of ambient temperature and crosswind on thermo-flow performance of the tower under energy balance of the indirect dry cooling system , 2015 .

[20]  Chunjiang Zhao,et al.  A review of computational fluid dynamics for forced-air cooling process , 2016 .

[21]  Y. Tominaga,et al.  Numerical simulation of dispersion around an isolated cubic building: Model evaluation of RANS and LES , 2010 .

[22]  A. Sadiki,et al.  Numerical Investigation of Flow through a Valve during Charge Intake in a DISI -Engine Using Large Eddy Simulation , 2019, Energies.

[23]  Riccardo Buccolieri,et al.  Numerical simulation of atmospheric pollutant dispersion in an urban street canyon: Comparison between RANS and LES , 2011 .

[25]  Yoshihide Tominaga,et al.  CFD Modeling of Pollution Dispersion in Building Array: Evaluation of turbulent scalar flux modeling in RANS model using LES results , 2012 .

[26]  J. W. Hodgson,et al.  An investigation of the effects of flue gas injection on natural draft cooling tower performance , 1997 .

[27]  A. Jahangiri,et al.  Thermal performance improvement of the three aligned natural draft dry cooling towers by wind breaking walls and flue gas injection under different crosswind conditions , 2019, International Journal of Thermal Sciences.