Multifunctional surface structure for condensation enhancement and preparation method and use thereof
The invention belongs to the technical field of phase-change heat transfer enhancement, and particularly discloses a multifunctional surface structure and a preparation method and use thereof for condensation enhancement. The multifunctional surface structure for condensation enhancement includes a copper substrate. A plurality of Tesla valve passages are parallelly arranged on a surface of the copper substrate. A diamond bump with a flared slope is arranged on the surface of the copper substrate between each side passage and the corresponding main passage. The surface of the copper substrate and surfaces of the diamond bumps and the Tesla valve passages are covered with a composite hydrophobic coating. The heat-transfer performance of the surface structure is remarkably improved.
1 . A multifunctional surface structure for condensation enhancement, comprising a copper substrate, wherein a plurality of Tesla valve passages are parallelly arranged on a surface of the copper substrate, each said Tesla valve passage comprises a main passage and a plurality of side passages distributed on two sides of the main passage, a diamond bump with a flared slope is formed in the copper substrate between each said side passage and the corresponding main passage, and pointed ends of the diamond bumps are distributed to be parallel with at least a portion of a flow direction of the Tesla valve passages and at least one pointed end of the diamond bumps intersects at least one portion of the Tesla valve passages; and the surface of the copper substrate and surfaces of the diamond bumps and the Tesla valve passages are covered with a composite hydrophobic coating.
2 . The multifunctional surface structure for condensation enhancement according to claim 1 , wherein the diamond bumps have a height of 0.506 mm and a width of 1.016-1.644 mm, and a distance from a top to edges of the diamond bumps is 1.56-2.19 mm; and the Tesla valve passages have a depth of 0.51 mm and a width of 0.935 mm.
3 . The multifunctional surface structure for condensation enhancement according to claim 1 , wherein the composite hydrophobic coating is an Ag/PTFE hybrid coating.
4 . The multifunctional surface structure for condensation enhancement according to claim 3 , wherein a silver coating in the Ag/PTFE hybrid coating is a porous silver coating and has a thickness of 1.2 μm; and a PTFE coating in the Ag/PTFE coating has a thickness of 1.2 μm and a water contact angle of 112.03°.
5 . The multifunctional surface structure for condensation enhancement according to claim 2 , wherein the diamond bumps have a width of 1.337 mm and a length of 2.018 mm, and the distance from the top to the edges of the diamond bumps is 1.90 mm.
6 . A preparation method of the multifunctional surface structure for condensation enhancement according to claim 1 , comprising:
(1) pretreatment of a base material: soaking the copper substrate in a 0.1 mol/L diluted hydracid solution for 10 min; then, washing the surface of the copper substrate with deionized water; then, cleaning the surface of the copper substrate in acetone and ethyl alcohol; and finally, washing again the surface of the copper substrate with deionized water, and blow-drying the surface of the copper substrate;
(2) machining of the diamond bumps and the Tesla valve passages: machining the diamond bumps and the Tesla valve passages on the pretreated surface of the copper substrate; and
(3) preparation of the composite hydrophobic coating: adding 0.04 g of perfluorooctanoic acid powder to 53 g of deionized water, and stirring until the perfluorooctanoic acid powder is completely dissolved; next, adding 17 mL of a AgNO 3 solution with a concentration of 0.1 mol/L to obtain a AgNO 3 /perfluorooctanoic acid solution; soaking the surface of the copper substrate with the diamond bumps the and Tesla valve passages in the AgNO 3 /perfluorooctanoic acid solution for 2 min, then taking out the surface of the copper substrate, and naturally air-drying the surface of the copper substrate; and immersing the treated surface of the cooper substrate in a PTFE nano-coating solution by a dip coating method, then taking out the surface of the copper substrate, and naturally air-drying the surface of the copper substrate for more than one day to form the Ag/PTFE hybrid coating on the surface of the copper substrate and the surfaces of the diamond bumps and the Tesla valve passages.
7 . The preparation method of the multifunctional surface structure according to claim 6 , wherein the PTFE nano-coating solution has a mass fraction of 5% and a nano-particle size of 500 nm.
8 . A condensation heat transfer device comprising a multifunctional surface structure for condensation enhancement according to claim 1 .