Enhanced steam condensation heat transfer on a scalable honeycomb-like microporous superhydrophobic surface under various pressures

Abstract

Steam condensation was studied experimentally over a honeycomb-like microporous superhydrophobic surface, as fabricated by electrodeposition method, under various condensing pressures. The condensing pressure was varied from 4 kPa to 13 kPa, based on the typical operating conditions of condensers in coal-fired power plants. Over this range of pressure, stable coalescence-induced condensate droplet jumping was realized on the honeycomb-like surface with hierarchical micro-/nanostructures, leading to a significantly enhanced condensation heat transfer over that on a smooth hydrophobic surface at low degrees of subcooling (<10 K). Both the frequency and amount of jumping droplets were observed to decrease at lower pressures because of the slower condensate production, and at higher degrees of subcooling as a result of the occurrence of surface flooding. However, increasing the pressure was found to lead to delayed onset of surface flooding due to the pressure-boosted droplet jumping phenomenon. The good performance and rapid, scalable fabrication of this type of modified surface on curved copper objects shed light on its great potential for applications in industrial condensation equipment operated under multiple pressures.