Modified surface for condensation

Patent metadata

Field	Value
Publication number	US-11536520-B2
Application number	US-201916966751-A
Country	US
Kind code	B2
Filing date	Feb 2, 2019
Priority date	Feb 2, 2018
Publication date	Dec 27, 2022
Grant date	Dec 27, 2022

Abstract

The present invention relates to a method of enhancing heat transfer of metallic surfaces by (1) fabricating hierarchical micro-nanostructured surfaces using etching processes, and (2) fabricating hydrophobic and hydrophilic regions, using a printing or a coating technique, followed by etching. The said method enhances the density of condensation sites over a metallic surface and additionally facilitates the departure of condensed droplets from the surface. Such a surface also enhances the sensible heat transfer characteristics, and improves the coefficient of performance (COP) of refrigeration systems for applications like atmospheric water generators, dehumidifiers, air conditioners, etc.

First claim

We claim:

1. A modified metal surface for condensation of fog, humidity and water vapor comprising a metal and scalable hierarchical micro-nanostructures, wherein said metal is aluminium and said scalable hierarchical micro-nanostructures are made of AlOOH/Al 2 O 3 ,
wherein said modified metal surface contains hydrophilic-hydrophobic patterned regions created by a coating technique or a printing technique selected from spray coating and screen printing,
wherein said scalable hierarchical micro-nano structures are prepared by an etching process, and
wherein said scalable hierarchical micro-nano structures are etched onto a coated or printed surface formed by the coating technique or the printing technique, to regulate a condensation process.

2. The modified metal surface as claimed in claim 1 , wherein the scalable hierarchical AlOOH/Al 2 O 3 micro-nanostructures comprise micron-sized cones with nanostructured bumps, as nucleation sites for droplets.

3. The modified metal surface as claimed in claim 1 , wherein the scalable hierarchical AlOOH/Al 2 O 3 micro-nanostructures comprise micron-sized conical structures of 10-20 μm in height, the micron-sized conical structures being completely covered with nano-bumps of 500 nm in height.

4. The modified metal surface as claimed in claim 1 , wherein the modified metal surface is etched in a mild basic medium selected from the group consisting of dilute NaOH and KOH, or is etched in a mild acidic medium selected from the group consisting of dilute FeCl 3 , atmospheric H 2 O 2 , HF, and HCl.

5. The modified metal surface as claimed in claim 1 , wherein the modified metal surface is etched using an etching process involving soft chemistry using a solution selected from the group consisting of glucose, sugars and amino acids.

6. The modified metal surface as claimed in claim 1 , wherein ink used in said printing or coating technique is a graphenic/graphitic ink which is etch-resistant, hydrophobic, thermally conducting, and coatable or printable on a metallic surface.

7. The modified metal surface as claimed in claim 1 , wherein the modified metal surface improves heat transfer efficiency of heat exchanger coils for applications in heating, air conditioning and is capable of being used for condensation and water collection for atmospheric water generators.

8. The modified metal surface as claimed in claim 1 , wherein the coating technique is spray coating and the printing technique is screen printing.

Assignees

• Indian Inst Tech Madras

Inventors

• Thalappil Pradeep
• Nagar Ankit
• Kumar Ramesh
• Pillalamarri Srikrishnarka

Classifications

• C23F1/20

  for etching aluminium or alloys thereof · CPC title

• F28F2245/04

  hydrophobic · CPC title

• F28D2021/0063

  Condensers · CPC title

• C23F1/36

  for etching aluminium or alloys thereof · CPC title

• F28F2245/02

  hydrophilic · CPC title