Improved Heat Transfer by RF Plasma Produced Structured Surfaces

Structured surfaces are needed for improving the heat transfer in a lot of industrial processes. The paper deals with the production and the characterization of coatings with rough and porous surface. Structured coatings of inconel or copper are deposited on copper tubes by means of radio-frequency vacuum plasma spraying. The microstructure as well as the surface roughness of the coatings are investigated. Boiling experiments are carried out on the coated tubes to measure their heat transfer coefficient. The results show that the coated tubes exhibit improved heat transfer values in comparison to smooth tubes. The enhancement ratio can reach more than 20 for inconel coatings.