Desalination setup coated by silicone epoxy nanocomposite: A study on hydrophobic characteristics and condensation mechanisms

Abstract

The formation of tortuous filmwise condensation in desalination setup alongside with reduction in thermal conductivity is a challenge accompanied by efficiency loss. This issue is directly influenced by hydrophobicity, which is a function of surface roughness, as well as surface chemistry. In this sense, the hydrophobicity of variant silicone epoxy based nanocomposites was evaluated to identify the optimum proportion composite for surface condensation of desalination setup. To this end, three types of fumed silica with distinct surface chemistry were utilized in a matrix at the weight percentage of 0.5, 1, 1.5, and 2. To investigate the hydrophobicity, roughness, and distribution of reinforcement, a series of characterization techniques, including contact angle, AFM, and FESEM were used. It was found that, in comparison to pure matrix, the nanocomposite modified with 5 wt % of hydrophobic additive and 0.5 wt % of hydrophilic fumed silica nanoparticles (SE/5B/0.5R200) has the highest contact angle (about 35%) and roughness (13 times), due to the migration of nanoparticle onto the surface. Also, coating the condensation surface of the desalination setup with optimum thickness, i.e. 60 × 10−6 m, resulted in the efficiency improvement by about 33 % compared to the uncoated setup, even after 168 hrs. Indeed, dropwise condensation, straight path movement of droplets, besides thermal conductivity adjust the efficiency.