Slippage on Porous Spherical Superhydrophobic Surface Revolutionizes Heat Transfer of Non-Newtonian Fluid

In this study, a new strategy to achieve high-efficient heat transfer for non-Newtonian fluids with slippage using a stably prepared superhydrophobic coating is presented. A superhydrophobic coating is prepared on the inner surface of a sleeve at specific shear stress. The slippage and heat-transfer processes of the typical non-Newtonian fluid–1% carboxymethyl cellulose solutions on the superhydrophobic coating are investigated simultaneously. A novel porous spherical type of superhydrophobic coating with a contact angle of 168° is obtained. It is found that the shear stress in electrodeposition is a key parameter to control the morphology and wetting ability of the superhydrophobic coating. The slip length and enhancement factor of heat transfer for the non-Newtonian fluid on the coating are found in a range of 20–900 µm and 1.47 experimentally. A new parameter is proposed as Reynolds number Re divided by the dimensionless slip length l_s* (Re/l_s*) for the heat-transfer enhancement with slippage, which can be used as the guide for designing coating and selecting the operating conditions. The Re/l_s* is <4, which can enhance the heat transfer via the slippage.