This study investigates the potential gain in operating volume flow rate and static efficiency for an induced draught fan arrangement by reducing the outlet kinetic energy loss. The reduction is achieved through pressure recovery, which is the conversion of dynamic pressure into static pressure. Downstream diffusers, stator blade rows, or a combination of these can recover pressure. Six different discharge configurations are tested for a fan. An annular diffuser with equiangular walls at an angle of 22° from the axial direction and a length equal to the fan diameter recovers the most pressure over a range of volume flow rates. The diffuser causes the operating volume flow rate and static efficiency to increase by 6.3 % (relative) and 20 % (absolute), respectively, compared to the initial design point of the particular fan.

No abstract

Wind generally reduces the thermal effectiveness of air-cooled condensers (ACCs). Therefore, this study investigates wind screens as a means to improve the performance of a 20-fan induced draft ACC under windy conditions. Two wind-screen configurations are tested: walls extending above the fan platform (termed wind walls), and walls extending below the fan platform (termed wind skirts). The performance of this five-by-four ACC is evaluated using the open-source computational fluid dynamics code, OpenFOAM. The performance is first analyzed under windless operating conditions and then when the ACC is subjected to wind speeds of 3, 6, and 9 m/s directed along the shorter and longer axes of the ACC. Under windless conditions, wind walls increase the ACC's thermal effectiveness by 1.0 %. Wind skirts, however, reduce the effectiveness by 1.8 %. Depending on the wind speed and direction, wind walls increase the mean thermal effectiveness of the ACC by 0.3 to 3.9 % under windy conditions. Wind skirts, on the other hand, are only beneficial at higher wind speeds: At 3 m/s, the effectiveness declines by 1.4 to 2.1 %; at 6 m/s, the change in effectiveness ranges from -0.4 to 2.2 %; and at 9 m/s, the effectiveness increases by 2.4 to 3.8 %. Wind walls are therefore considered more effective than wind skirts for the tested range of wind speeds.