A numerical study on the effect of roof windbreak structures in an air-cooled system

Abstract The ambient wind velocity seriously affects the heat transfer performance in a Direct Air-Cooled Condenser (DACC). The heat transfer rate of an upstream heat exchanger unit is lower than that in other heat exchanger units under unfavorable ambient winds. The current work uses Computational Fluid Dynamics (CFD) to numerically simulate and analyze the effect of roof windbreak system on the DACC in a 2 × 350 MW power station. The distortion of the air flow, and the hot air recirculation rate at the fan inlet surface were studied at different ambient wind velocities. Our results show that the vertical length L1, inclined length L2, and inclination angle α on the roof windbreak line screen affect the performance of the DACC significantly. The analysis further shows that the optimal performance of the DACC can be achieved under the structure size of L1 = 30 m, α = 60°, and L2 = 5 m. The air flow decreases at the no wind or low wind velocity due to setting of the windbreak line screen. Therefore, the height of the platform needs to be adjusted to meet the suction space requirement for the fan.

[1]  Bo Yu,et al.  Performance prediction of an improved air-cooled steam condenser with deflector under strong wind , 2010 .

[2]  Detlev G. Kröger,et al.  Effect of inlet flow distortions on fan performance in forced draught air-cooled heat exchangers , 1995 .

[3]  Peiqing Liu,et al.  Numerical investigation of hot air recirculation of air-cooled condensers at a large power plant , 2009 .

[4]  C. J. Meyer Numerical investigation of the effect of inlet flow distortions on forced draught air-cooled heat exchanger performance , 2005 .

[5]  Detlev G. Kröger,et al.  Contributors to increased fan inlet temperature at an air-cooled steam condenser , 2013 .

[6]  Yongping Yang,et al.  Measures against the adverse impact of natural wind on air-cooled condensers in power plant , 2010 .

[7]  J. P. V. Doormaal,et al.  ENHANCEMENTS OF THE SIMPLE METHOD FOR PREDICTING INCOMPRESSIBLE FLUID FLOWS , 1984 .

[8]  Detlev G. Kröger,et al.  Numerical investigation of fan performance in a forced draft air-cooled steam condenser , 2006 .

[9]  He Weifeng,et al.  Influence from the rotating speed of the windward axial fans on the performance of an air-cooled power plant , 2014 .

[10]  Xiaoze Du,et al.  Influences of wind-break wall configurations upon flow and heat transfer characteristics of air-cooled condensers in a power plant , 2011 .

[11]  Detlev G. Kröger,et al.  Numerical investigation of the effect of fan performance on forced draught air-cooled heat exchanger plenum chamber aerodynamic behaviour , 2004 .

[12]  Detlev G. Kröger,et al.  Performance Trends of an Air-Cooled Steam Condenser Under Windy Conditions , 2008 .

[13]  Detlev G. Kröger,et al.  The effect of screens on air-cooled steam condenser performance under windy conditions , 2010 .

[14]  T. W. von Backström,et al.  Effect of cross-flow on the performance of air-cooled heat exchanger fans , 2002 .

[15]  T. W. von Backström,et al.  Numerical investigation into the effect of cross-flow on the performance of axial flow fans in forced draught air-cooled heat exchangers , 2006 .