Corroding Condenser Fins

The most prevalent thing that limits the life of an air-conditioning unit is the outside coil. This is more evident in climates that have a higher salt content in their air. Regular cleaning of the outside coil can eliminate this. Yet as most people are penny wise and pound foolish they do not want to spend the money to get a technician to come out and do it. Yet they do not do it themselves. This leads to an eroding of the unit that in not inline with the wear of the rest of the system.

The first step in solving a problem using the TRIZ method is to identify what the problem is. In our case we have condenser coils that are not being cleaned on a regular basis.

After we establish what is wrong we state the ideal result. In our case the ideal result would be to clean the coils periodically without a technicians presence.

Looking through the 39 Engineering Parameters we find;

16. Durability of nonmoving object: The condenser fins are made out of a thin metal to allow for heat loss but also creates a susceptibility for corrosion.

25. Waste of time: Brining out a technician to clean the coil is time consuming and can be expensive.

30. Harmful factors acting on object: When the condensation of the fins meets with the salt and abrasives in the atmosphere we find a galvanic corrosion occurring limiting the lifespan of the coils.

31. Harmful side effects: The constant heating and cooling of the coils increases the susceptibility to galvanic corrosion.
Now that we have established what our problems are we need to ask ourselves questions about how we can change them. Using the 40 inventive principles of TRIZ we can go about this in a more structured environment then unstructured brain-storming could allow.

2 Extraction:
a. Extract (remove or separate) a “disturbing” part or property from an object, or
b. Extract only the necessary part of property

Extract the salt or abrasive elements from the coil to limit one of the catalysts for galvanic corrosion.

3 Local Quality:
a. Transition from a homogeneous structure of an object or outside environment/action to a heterogeneous structure.
b. Have different parts of the object carry out different functions.
c. Place each part of the object under conditions most favorable for its operation.

Add a self cleaning apparatus to the outside unit itself.

5. Combining:
a. Combine in space homogeneous objects or objects destined for contiguous operations.
b. Combine in time homogenous or contiguous operations.

Add a self cleaning apparatus to the outside unit itself that operates off of the compressor in the unit itself.

11 Cushion in advance: Compensate for the relatively low reliability of an object by countermeasures taken in advance.

Place a corrosion resistant coating on the coil fins or place zinc anodes near the coils like what is placed on boat propellers.

15 Dynamicity:
a. Make an object or its environment automatically adjust for optimal performance at each stage of operation.
b. Divide an object into elements which can change position relative to each other.
c. If an object is immovable, make it moveable or interchangeable

If there is a cleaning coil system in place it can be attached to the outdoor unit itself. This will enable electrical systems to shut down when the cleaner is spraying.

30 Flexible membranes or thin film:
a. Replace traditional constructions with those made from flexible membranes of thin film.
b. Isolate an object from its environment using flexible membranes or thin film.

A thin membrane could be put on the surface of the fins to eliminate the ability of the moisture to collect on the metal itself. Care must be given for the heat transfer capability of the fins.

From this simple exercise we have come up with some good ideas for eliminating corrosion on the metallic fins of an outdoor air-conditioning coil. These solutions include some sort of spray system that cleans the coils, or a thin membrane placed over coil fins. How these could be created is in the hands of the engineers but the ideas are now out there.