Enhancing the Heat Exchanger Performance Through the Use of High Temperature Resistant Superhydrophobic Nanocomposite Coatings

Steam-to-liquid heat exchangers are used extensively in industrial applications, including chemical and food processing and electric power generation. In present systems, the formation of a condensate film of water on the surface of a heat exchanger tube reduces the heat transfer coefficient. This effect occurs because the thermal conductivity of the condensed water is only a fraction of that of the metallic heat exchanger tube material, leading to an overall reduction of the thermal conductivity. One means of overcoming this effect is to promote the vapor condensation in the form of droplets, instead of a continuous film. However, to date, it has remained a challenge to achieve this "dropwise" condensation in practical heat exchangers. This project will demonstrate the feasibility of dropwise condensation in industrial heat exchangers through the use of a high-temperature-resistant and durable nanocomposite coating that is superhydrophobic. An ultra-thin nanocomposite coating will be deposited on an aluminum heat exchanger tube, which will be tested first in the laboratory and then in an industrial setting. Commercial Applications and other Benefits as described by the awardee: Changing filmwise condensation to dropwise condensation would enhance the heat transfer coefficient by an order of magnitude, leading to substantial savings in energy in retrofit applications and additional savings in size reductions of new heat exchanger installations.