Abstract
Polydimethylsiloxane modified SiO2/organic silicon sol (PDMS-SiO2/SS) hybrid coating was synthesized via a simple two-step modification route. The nanoparticles (NPs) of PDMS-SiO2 were synthesized through a high temperature dehydration reaction by using silica and excessive PDMS. The NPs lapped with each other and formed a branch and tendril structure. Organic silicon sol (SS) added as basement introduced a hydrophobic group and protected the structure of the NPs. The PDMS-SiO2/SS hybrid coating exhibits a superhydrophobic performance with a maximum water contact angle of 152.82°. The frost test was carried out on a refrigerator evaporator, and the results showed that the coating did not merely delay the frost crystal time about 113 min but also increased the frost layer process time. Meanwhile, the defrosted water droplets rolled off from the coated surface easily which is a benefit for frost suppression performance of the next refrigeration cycle.
Highlights
It is well known that frost will occur when water vapor in the air contacts a cold surface with a surface temperature lower than the dew point in refrigeration, low temperature storage, air conditioning heat pumps and other low temperature fields [1,2,3]
Numerous methods and techniques for inhibiting frosting have been reported, which can be classified into three categories, one is reducing air humidity [8]; the second is using the effect of external field energy [9]; the third is surface modification treatment [10]
The results showed that the surface properties and temperature played a key role in the frosting formation rate and frosting cycle time
Summary
It is well known that frost will occur when water vapor in the air contacts a cold surface with a surface temperature lower than the dew point in refrigeration, low temperature storage, air conditioning heat pumps and other low temperature fields [1,2,3]. As the frost layer is a porous material composed of ice crystals and air, its effective thermal conductivity is low. The existence of a frost layer on structures will increase the heat transfer resistance and reduce the heat transfer coefficient, cause serious problems, such as power transmission, economic losses, and even inability to work normally in cold regions [4,5,6,7]. Numerous methods and techniques for inhibiting frosting have been reported, which can be classified into three categories, one is reducing air humidity [8]; the second is using the effect of external field energy [9]; the third is surface modification treatment [10]. The methods of air humidity control and external field energy are seldom used in engineering. The surface modification method has broad application prospects because of its advantages such as low cost, convenient processing, and so on
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