Clean Chemistry for Fuel Cell Technology

We are living in a time where an abundance of energy resource exploration is underway. Engineers are engaged in developing the cleanest and most efficient power that is also affordable, durable, available and of high performance. Hydrogen fuel cell technology, a new power source that is still being developed for high efficiency, is the cleanest form of energy, as it has very low to zero emissions compared to combustion engines. One coatings company is collaborating with automotive Tier One suppliers that manufacture heat exchangers for vehicles operating with hydrogen fuel cells to keep them running as clean and efficiently as possible.

While Circle Prosco Inc. (Bloomington, Indiana) has been supplying lubricants for stamping radiator header plates and the thin fins that zig zag between the tubes for 30 years, its technical team has earned a reputation for problem solving. When their Tier One customers were required to meet a higher internal cleanliness specification for radiators built for hydrogen fuel cell vehicles, they asked CPI for help. Now the company is applying its 50 years of metal finishing expertise to meet the stringent cleaning specifications of new energy heat exchangers. The new chemistry cleans the inorganic contaminants inside a heat exchanger and forms a pretreatment/conversion coating that cleans the inorganic contaminants inside a heat exchanger, which also keeps the coolant clean that runs through the system. When all components are clean, the fuel cell runs more productively, and its life is increased.

Specializing in chemistry used in high volume automotive applications, Circle Prosco is designing its latest formulation to clean these parts in a short amount of time, making the solution commercially viable.

“One of the challenges of this project is that the major contaminant must be cleaned from within the small passages of the fully manufactured radiator,” says Bill Morton, product application manager, lubricants/aluminum coatings at Circle Prosco. The standard automotive heat exchanger manufacturing process leaves a lot of residual inorganic material on the interior of the heat exchanger.

“The contaminant is very tenacious and hard to clean,” Morton continues. “It’s been sitting on aluminum, and aluminum can be damaged and degraded by strong acid chemistry and strong alkaline chemistry.”  

Despite the obstacles, Morton has been successful in leading efforts to create an aluminum-safe cleaning chemistry that has taken three years of R&D. After the project that began with close collaboration with customers and simultaneous developments in the heat exchangers for hydrogen fuel cells, the new cleaning chemistry is ready to be implemented, although R&D is ongoing.

Stages of the cleaning process

Circle Prosco works together with its customers to move their projects from feasibility testing to prototyping, process validation and the start of production. In general, its new cleaning chemistry is designed to be implemented in the first step of the radiator’s cleaning process.

Morton explains that this cleaning solution will circulate through the radiator parts with standard chemically compatible piping, hoses and pumps. “It is not so exotic that it can’t be implemented by our customers as we move forward,” he says.

He adds that like any chemical process, concentration of chemistry, time of exposure and temperature will control the reaction which occurs during this stage.

Then, the rinsing step is next, which is typical of a metal finishing process.

The passivation step is the third step, which imparts a thin corrosion-resistant coating that’s between 25 and 30 nanometers and reacts to the aluminum surface. “We want it to coat all the interior surface evenly and completely, but we don’t want the film to be so thick that it would impede the heat exchange capability or close off the passages through this heat exchanger,” Morton explains.

Passivation provides the surface with a corrosion resistant coating. As a result, part longevity and clean coolant will be compatible with the fuel cell, giving it long life as well.

Morgan Fraga, director of sales and marketing at Circle Prosco, adds that the thin nano coating layer uses the same technology that is in zirconium pretreatment chemistry for steel. “The longer your iron phosphate touches a product, the more coating will develop,” she says. “The zirconium coating is self-limiting, so you can leave it on a part for 10 minutes in a phosphate-free zirconium stage, and you’ll get the same coating you get after 1 minute. But the iron phosphate is going to keep building and building.”

After the passivation process, another rinse cycle occurs. Then, the product is ready to be presented to the customer per its criteria, which will be either a fully dry or not fully dry subassembly, Morton explains.

R&D continues

Circle Prosco persists in its R&D work on the cleaning step chemistry and the process design. The application process and results will depend on different variables in the heat exchanger that is still undergoing development and incremental changes. 

The company will continue to develop its passivation process alongside of the evolution of hydrogen fuel cell technology.