Study On Biomimetic Hydrophilic/Hydrophobic Gradient Surfaces Suitable For Fog Collection In Arid Areas

Scallions are rich in minerals,vitamins,and carbohydrates,and have antibacterial properties,making them an indispensable part of human consumption.However,the northwest region is short of water.In order to save water and preserve soil moisture,green onions are generally planted in greenhouse.However,due to the lack of water,the common irrigation methods are not practical.According to the investigation,there is a large amount of water in the air,so collecting water from the air is also a way to irrigate scallions.The main research content of this article is as follows:(1)Preliminary construction of a hydrophilic/hydrophobic gradient surface.This article first considers the perspective that the back of desert beetles and cactus spines can collect water vapor in the air,and then designs a surface that can achieve precise drip irrigation on the roots of scallions based on their shape and size.Through observation,the leaf veins of camphor trees are arc-shaped,which can adapt to the external dimensions of scallions.Then,combined with the structural characteristics of desert beetles’ backs and cactus spines that can transport water,a hydrophilic/hydrophobic gradient surface is preliminarily designed.(2)Optimize the parameters of the circular arc water delivery path.The preliminarily designed hydrophilic/hydrophobic gradient surface requires theoretical verification of its shape parameters for transporting droplets at all levels of water transport paths,and then the optimal parameters can be obtained through exploration.The main parameters of the water conveyance path are angle and arc radius,and the angle and arc radius of the first and second water conveyance paths are the same.Therefore,first take a section of the water delivery path and explore the impact of different angles and arc radii of the water delivery path on the transportation of droplets.Through experiments,it is concluded that the water delivery path with an angle of 4 ° and an arc radius of 40 mm is the most suitable application.Secondly,in order to prevent the wide water delivery path from affecting the efficiency of mist collection,the water delivery path is divided into multiple segments and connected in series.However,the narrow to wide ratio at the junction can affect the passage of droplets,so it is necessary to explore the narrow to wide ratio that droplets can pass through.Experiments have shown that when the width to width ratio is 0.6,droplets can pass through the junction.In addition,by laying a water film on the water delivery path and optimizing the shape of the connection,we explore whether it is possible to reduce the critical value of the narrow to width ratio of the droplet passing through the connection.Research has shown that laying a film can make the droplet pass through the connection with a narrow to width ratio of 0.45,which can reduce the critical value of the droplet passing through the connection.However,optimizing the shape of the connection has little effect on the droplet passing through the connection.Therefore,the width to width ratio of the connection is set to 0.45,and a water film is laid to extend the series water delivery path to the length of the preliminary construction of the primary water delivery path.The experimental results indicate that droplets can still pass through the connection and move to the endpoint.(3)Construct a new hydrophilic/hydrophobic gradient surface to achieve mist collection.According to the previous research results,a new fog water collecting surface was designed.The wedge angle of the water delivery path was set to 4 °,the arc radius was set to 40 mm,and the width ratio at the connection of the water delivery path was set to 0.45.Experiments were carried out in the space simulating the temperature and humidity in the greenhouse.After that,experiments were also carried out on the preliminarily constructed fog water collecting surface.Through comparison,it was found that the newly designed hydrophilic/hydrophobic gradient surface had a large amount of fog water collecting,High water collection efficiency.