Enhanced Steam Condensation on Meso-and Micro-scale Profiled Surfaces

Depending on their specific surface energy transition metals like copper, nickel and their alloys are appropriate to induce dropwise condensation, in particular of water steam on sub-cooled micro-scale profiled surfaces. Special tube probes made of alloyed steel No. 1.4301 with meso-scale profiled surface, micro-scale profiled probes and combined mesoand micro-scale profiled probes made of copper No. 2.0090 were designed, prepared and studied. The principal result is that drop condensation was induced successfully and a significant increase in heat flux density by at least 80% was obtained. This is correlated with augmented heat transmittance, condensate formation and the mass flow of the cooling fluid quantified by the Reynolds number. It could be transferred effectively to a newly constructed prototypic water steam condenser, evaluated by experiment and by modelling using methods of numerical calculation (CFD). Inherently, the micro-scale profiled surfaces cause an increase in the surface tension of the fluid as indicated by contact angle measurements. Further investigation is necessary regarding special meso-, microand nano-scale profiled surfaces potentially with additional substantial coatings or artificially prepared compound substrates and textured composites to adjust the specific surface properties, thereby achieving the ability to induce enhanced condensation of a wide range of polar, non-polar and olefin substances in energy and process technology.