Polymeric surface coatings with nanoporous microparticles for boiling intensification in advanced steam accumulators

Pool boiling of liquid water has many practical applications in daily life and industry, including steam accumulators. Thus, pool boiling on polymeric surface coatings with nanoporous microparticle addition for boiling heat transfer coefficient (HTC) enhancement and potential for solid-solid phase change material (PCM) encapsulation have been studied. The study focuses on the effect of surface wettability on the boiling HTC and the vapor barrier properties of the different polymeric surfaces, measured by means of corrosion analysis on the substrate surface.Pure polyvinylidene fluoride (PVDF) yields high HTC at low wall superheat (ΔTwall) values, both with hydrophilic and binary nanoparticle addition. Moreover, combination of polyimide (P84) with hydrophilic and binary mixture of nanoporous microparticles shows great thermal performance in the same ΔTwall regime. In addition, PVDF and P84 seem to be promising candidates for solid-solid PCM encapsulation, as they showed good mechanical resistance and vapor permeation properties, with and without containing hydrophilic silica nanoporous microparticles. Hydrophobic silica nanoporous microparticle addition led to an immediate vapor blanket generation that significantly hindered heat transfer and augmented substrate surface corrosion.