58735 - Effect of Tip Vortex Reduction on Air-Cooled Condenser Axial Flow Fan Performance: An Experimental Investigation 

In the quest for water conservation in arid and semi-arid countries such as South Africa, air-cooled condensers (ACCs) are popular dry cooling systems employed in modern power generation. These systems reject heat to the environment via banks of heat exchanger bundles and a multitude of large axial flow fans. Large power stations, such as Eskom’s Matimba plant, employs 288 fans of approximately 9m diameter each. The scale and continuous operation of these fans result in the ACC being a major power consumer. Ensuring optimal operating efficiency of these fans will therefore benefit auxiliary power consumption, cooling system stability and overall plant efficiency.

Secondary flows at the blade tip region play an important role in axial flow fan performance. Research by Corsini et al. (2007) indicates that fan blade endplate configurations have an impact on both fan performance and noise. An experimental study by Wilkinson and Van der Spuy (2015) concluded that single-sided blade tip endplates shows potential to improve fan performance at larger tip clearances. This study follows on the work by Wilkinson and Van der Spuy (2015) by targeting a further reduction in fan blade tip vortices to improve fan efficiency, through the experimental implementation of improved endplate concepts.

A 1/6^th scale fan of 1.5m diameter was used in experiments, which represents a model of a fan developed specifically for use in large ACCs. Tests were conducted in a standard BS848 type A fan test facility. The testing regime considered two improved endplate concepts and compared results to the un-modified fan performance.

Results indicate that the addition of the improved endplates to the fan blade tips make a significant difference to the fan performance. The implementation of such endplates may increase or decrease fan static efficiency, depending on the fan flow rate as well as the specific endplate configuration.

References

Corsini A., Rispoli F., Sheard, A., 2007. Development of improved blade tip endplate concepts for low-noise operation in industrial fans. Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy, Volume 221, pp. 669-681.

Wilkinson, M.B. and Van der Spuy, S.J., 2015. The effect of fan tip configuration on air-cooled condenser axial flow fan performance. Fan 2015, pp. 1-12, Lyon, France.