US20130305748A1

US20130305748A1 - Icephobic coating on the condenser cold side

Info

Publication number: US20130305748A1
Application number: US13/475,221
Authority: US
Inventors: Sapan N. Shah; Hal J. Strumpf; Adel Elsayed; Vipul Patel
Original assignee: Honeywell International Inc
Current assignee: Honeywell International Inc
Priority date: 2012-05-18
Filing date: 2012-05-18
Publication date: 2013-11-21

Abstract

An icephobic coating is disposed on at least a cold side of a condenser in an environmental control system (ECS) of an aircraft. By applying the icephobic coatings to the condenser, the adhesive strength of the ice can be significantly reduced. As a result, it is difficult for ice to stick on the condenser. The vibration in the system and the force of the air flow can then knock the ice particles off of the condenser, resulting in reduced ice buildup.

Description

BACKGROUND OF THE INVENTION

The present invention relates to apparatus and methods for preventing ice build-up and, more particularly, apparatus and methods for preventing ice build-up on the cold side of environmental control system (ECS) condensers.
The air temperature at the turbine exit in an ECS system can be sub-freezing. This causes moisture in the air to come out of the turbine as ice. This ice then sticks and starts building up on the cold side of the ECS condenser, which adversely affects the performance of both the condenser and the ECS.
Conventional processes to prevent ice from building up require features in the system such as a bypass gap, hot bars and the turbine bypass valve. These features decrease the overall performance as well as the reliability of the system.
As can be seen, there is a need for a method and apparatus that prevents ice from building up on a device because of sub-freezing air exiting a turbine in an ECS system.

SUMMARY OF THE INVENTION

In one aspect of the present invention, an icephobic composition for a structure in a sub-freezing air flow comprises of a silicon resin binder containing fumed silica and a chemical crosslinker.
In another aspect of the present invention, an environmental control system comprises a turbine supplying sub-freezing air to a condenser; a condenser adapted to receive the sub-freezing air; and an icephobic coating disposed on at least a cold side of the condenser.
In a further aspect of the present invention, a method for preventing ice buildup on a condenser comprises coating at least a cold side of the condenser with an icephobic coating.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of an environmental control system for an aircraft; and

FIG. 2 is a perspective view of offset fins that go into a condenser adapted to be coated with the icephobic coating of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description is of the best currently contemplated modes of carrying out exemplary embodiments of the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.
Various inventive features are described below that can each be used independently of one another or in combination with other features.
Broadly, embodiments of the present invention provide an icephobic coating that may be disposed on at least a cold side of a condenser in an environmental control system (ECS) of an aircraft. By applying the icephobic coatings to the condenser, the adhesive strength of the ice can be significantly reduced. As a result, it is difficult for ice to stick on the condenser. The vibration in the system and the force of the air flow can then knock the ice particles off of the condenser, resulting in reduced ice buildup.
Referring now to FIG. 1, air may be received by an ECS 20 from both the aircraft exterior as fresh air, and from the aircraft fuselage or other interior space as recirculation air. Fresh air can be supplied from cabin compressors 10 a, 10 b powered by motors 11 a, 11 b. The compressed air may pass through a primary heat exchanger 32 that may be disposed in a ram air heat exchanger circuit 56. The ram air heat exchanger circuit 56 may have ambient ram air passing therethrough, which cools compressed air in the primary heat exchanger 32, a secondary heat exchanger 34, and an air recirculation heat exchanger 36 located in the circuit 56. The ambient ram air may be drawn into the heat exchanger circuit 56 through a ram scoop during aircraft flight. When the aircraft is stationary, the ram air heat circuit 56 may be driven by an electric fan 54 disposed downstream of the heat exchangers 32, 34, 36 so the heat from the fan 54 is directed overboard rather than into the heat exchangers 32, 34, 36. The ambient ram air in the circuit 56 is cooler than the air passing through the heat exchangers 32, 34, 36, and therefore serves as a heat sink.
After the compressed air passes through the primary heat exchanger 32, the air is supplied to a bootstrap air cycle machine, referring specifically to a compressor 40 and a turbine 42 that either share the same rotating axis or are otherwise powered and rotated together. The compressor 40 can further pressurize and heats the air. The compressed air can then be supplied to the secondary heat exchanger 34, causing the compressed air to cool. During normal operation, an altitude valve 60 may be closed, causing the air to pass through a re-heater 44 and a condenser 46, and then through a water separator 48, which substantially dries the air. From the water separator 48, the air may again be heated in the re-heater 44, and then the hot and dry air may be supplied to the turbine 42. The turbine 42 may provide cooled air as a product of air expansion, and may forward the cooled air to the condenser 46, which supplies the air to the cabins in the aircraft fuselage 30.
The cooled air provided by the turbine 42 is typically sub-freezing. This can cause moisture in the air to come out of the turbine as ice. This ice may then stick and start to build up on the cold side of the condenser 46. When the condenser 46 is coated with an icephobic coating 50 (not shown in FIG. 1), the icephobic coating 50 may facilitate removal of ice by reducing adhesion to the underlying surface, allowing system vibrations or airflow to discard ice from the condenser.
Typical offset fins used in a condenser 46 is shown in FIG. 2. It should be noted that the icephobic coating 50 of the present invention may be applied to various condenser designs, including the offset fin surface 46, as shown, but also to plain fin and wavy fin condensers.
To create the coated condenser of the present invention, the icephobic coating 50 may be applied to the condenser surface 46 through any number of processes. For example, the icephobic coating 50 may be sprayed onto the condenser fins 46 or the condenser 46 may be dipped into the icephobic coating 50, for example.
In some embodiments of the present invention, the icephobic coating 50 may be applied to only a cold side of the condenser 46. For example, the icephobic coating 50 may be applied to about 50 percent of the length of the condenser 46. In some embodiments, the icephobic coating 50 may be applied to the entire surface of the condenser 46.
The icephobic coating 50 may be selected from a number of icephobic coatings. For example, the icephobic coating 50 may be applied as a silicone resin binder containing fumed silica particles and a chemical cross linker. The coating can be either sprayed onto the condenser fins or the entire condenser can be dipped into the coating.
It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.

Claims

We claim:

1. An environmental control system comprising:

a turbine supplying sub-freezing air to a condenser;

a condenser adapted to receive the sub-freezing air; and

an icephobic coating disposed on at least a cold side of the condenser.

2. The environmental control system of claim 1, wherein the icephobic coating is disposed on the entire condenser.

3. The environmental control system of claim 1, wherein the icephobic coating includes a silicone resin binder containing fumed silica particles and a chemical cross linker.

4. A method for preventing ice buildup on a condenser, the method comprising:

coating at least a cold side of the condenser with an icephobic coating.

5. The method of claim 4, wherein the icephobic coating is disposed on the entire condenser.

6. The method of claim 4, wherein the icephobic coating is disposed on a cold side of the condenser.

7. The method of claim 4, wherein the icephobic coating includes a silicone resin binder containing fumed silica particles and a chemical cross linker.

8. A method for preventing ice buildup on a condenser, the method comprising:

coating at least a cold side of the condenser with an icephobic coating, wherein the icephobic coating includes a silicone resin binder containing fumed silica particles and a chemical cross linker.