Effect of Wetted Floating Fins on Water‐Atmosphere Heat Exchange

Abstract

Wetted fins floating on water could be an alternative to increase the efficiency of cooling and evaporation ponds. This possibility is explored by presenting the laboratory results of fin effectiveness versus wind speed. The effectiveness is expressed by the coefficient of additional effective area, ε, which determines the water surface area that produces the same heat transfer as the fin area. For example, ε=0.6 means that 1 cm2 of fin area exchanges as much heat as 0.6 cm2 of the water surface area. In heated water (45–65°C), with wind speeds of 5 m/s, fins perpendicular to the wind have an ε=0.76, while fins parallel to the wind have an ε of 0.16. In natural water (<20°C), with fins perpendicular to the wind, ε varies from 0.26 to 1.2, as the wind varies from 1 m/s to 5 m/s. An evaporation experiment with uncontrolled environmental conditions suggests an overall value of ε=0.6. A span between fins of five fin heights is considered appropriate to apply these results. Floating fins may increase evaporation up to 24%. However, experiments on an extensive water surface are needed to establish the wave effects.