Effects of the forced convection induced by assistant fans on the thermal performance of an indirect dry cooling system

Abstract

Auxiliary forced convection induced by axial flow fans was introduced to improve the ventilation and heat dissipation of a large-scale dry cooling tower under crosswinds. A numerical model coupling aerodynamic characteristics of the fans, thermo-flow characteristics of the tower, and thermodynamic calculations of the condenser was developed. By altering fan layout position, compactness, and inclination, the induced effects on thermal performance of the indirect dry cooling system were studied. Results showed that at wind speeds below 6 m/s, it is best to arrange the fans horizontally on the inlet cross-section of tower body. On this basis, distributing the fans uniformly in three rings could reduce flow turbulence inside the tower and meanwhile increase the tower ventilation. A moderate inclination of the fans could improve the synergy between the ventilation directions of the fans and airflow directions inside the tower. The combination of these steps significantly enhances thermal performance of the indirect dry cooling system, and the caused drop in back pressure of the turbine exceeds 3 kPa. At high wind speeds, the vertical arrangement of the fans outside the radiators becomes the most-effective layout for alleviating the adverse wind effects by remarkably reducing air inflow deviation angles of the radiators.

Keywords

• Dry cooling tower
• Axial flow fans
• Mixed convection
• Thermal performance
• Numerical simulation