Hebei University of Engineering Zhang Jie Ren Yan Liang Huimin
Keywords: super-hydrophilic surface, super-hydrophobic surface, wettability, heat exchanger, cooling capacity
Household air conditioners usually use copper tube aluminum fin evaporators. In previous studies, great results have been achieved in the optimization and energy saving of air conditioning systems. In order to further improve its performance, this article starts from improving the surface performance of the heat exchanger, by studying the influence of the hydrophilicity and hydrophobicity of the heat transfer surface on the surface wettability, and adopting an optimized and reasonable heat exchanger surface to improve the work of the air conditioning system. Environment, improve the heat transfer efficiency of the heat exchanger. This article gives the concept of superhydrophilic surface and superhydrophobic surface, the domestic and international background and significance of these two concepts, and the current research status of various materials.
There are generally two preparation methods for super-hydrophilic surfaces: one is to use photocatalytic substances, and the other is to realize the modification of surface chemistry and geometric microstructure of the substance. Specifically, it includes methods such as immersing the copper surface with boiling water, dip coating, sputtering coating, chemical vapor deposition, liquid deposition and sol-gel. The author tested the evaporation and boiling process of the air conditioner heat exchanger and the condensation process of the finned tube heat exchanger through experiments, and analyzed the influence of the super-hydrophilic surface on the cooling effect of the air conditioner.
There are basically two methods for preparing superhydrophobic surfaces: one is to reduce the surface free energy of the solid by chemical methods, and the other is to increase the roughness of the solid surface on the hydrophobic surface. This paper qualitatively analyzes the steam condensation process on the hydrophobic surface of the fin and the influence of the size and shape of the superfluidic coating on the heat transfer effect.
The combination of superhydrophilic surface and superhydrophobic surface is of great significance for enhancing heat transfer. By using ultraviolet light to convert the surface from hydrophobic to hydrophilic or from hydrophilic to hydrophobic, the heat transfer can be controlled during boiling, heating and condensation, thereby improving the performance of the air conditioning heat exchanger. Therefore, in-depth study of the characteristics of various superhydrophilic and superhydrophobic surfaces is necessary to understand the influence of wettability on heat transfer efficiency during phase change heat transfer.