Design and fabrication of an internal condensation loop for effectiveness and robustness testing of nanostructured superhydrophobic steam condenser

Abstract

The Rankine cycle is at the heart of steam-electric power stations, which are responsible for generating about 90% of the world's electricity. Improving the efficiency of the cycle thus of great importance, and the greatest possible gain lies in improving the condensation process. Industrial condensers feature once-through water cooling, and the substantial amount of water they consume coupled with the increasing scarcity of freshwater supplies provides further motivation to focus on the condensation process. Condensation in these systems occurs predominantly via the filmwise mechanism, in which a thin film of water forms upon the condensing surface, adversely affecting its heat transfer abilities. However, forming a nanostructure and adding certain hydrophobic coatings on the heat exchanging surface of the condenser can render them superhydrophobic. This causes condensation to instead occur via the jumping droplet mechanism, which promises drastically improved heat exchanging performance. This thesis discusses the design and fabrication of an internal condensation loop which will allow us to test the heat transfer, fluid dynamic performance of the novel jumping droplet internal mode, and the durability and robustness of various hydrophobic coatings at the lab scale.