Cleaner Coils Boost Cooling Capacity

When a large food distribution facility was faced with major issues resulting from evaporator and condenser coils coated with dust, dirt, and production debris, it turned to EcoClear in Georgia and its deepcleaning system. The facility was looking to improve air flow, increase dehumidification, improve energy savings and reduce maintenance cost through a deep cleaning of the coils.

Coils with a layer of dust the thickness of a dime lose up to 21 percent in efficiency, because the coat of dust insulates the surfaces, thus reducing the cooling capacity. As reported by Tony Lundell, IIAR assistant technical director, in Condenser in June 2014, dirty evaporator coils “increase discharge head pressures, reduce compressor capacities, increase delivered supply air temperatures and overall increase energy usage.”

Simply put, properly cleaned evaporator coils will prevent food contamination, improve air flow and reduce operating costs.

“We had an area that needed more air flow,” the food distribution facility’s refrigeration manager said. “The evaporator coils had frosted up. Initially, we had a mechanic clean them and we thought it was thoroughly done, but we couldn’t see deep enough into the coils.”

The process involves self-contained pressure-washing rigs that are designed to deliver a high volume of water hot enough for sanitation. (While being treated, units are taken off-line for a limited amount of time.)

The technique employed is more important than the amount of pressure in order to avoid flattening the coil fins, causing a further reduction in the coil heat-transfer performance, and unknowingly pushing dirt deeper into the coil due to a lack of water volume.

Three employees worked on two five-foot-long evaporator coils, removing the fans from on top of the coils, removing the side panels, and then using biodegradable soaps and high-volume pressure washers to penetrate deep into the coils.

“With a clean coil, the temperature drop across the coil is typically 10 to 15 degrees. This company had a threedegree drop, which meant 50 percent less air flow. That costs around $5,000 per unit in energy efficiency annually,” said Brian Hindt, EcoClear owner.

That translates for a company that has 20 units to as much as $100,000 in energy savings.

The company’s deep-cleaning system improved heat transfer and air flow, allowing the facility to reduce running time and maintain temperature. “It takes longer for the cleaning, about one full day, but it’s the right way to do it,” the facility’s refrigeration manager said. “They put some pressure on the coils and they got them clean. Just looking at the coil I can see more humidity being picked up out of the air, more condensation falling off the coils into the drain pans, and the coils definitely aren’t freezing. I can also tell that the air flow has increased.”

EcoClear uses a proprietary software to estimate the cost savings produced by their complete cleaning and coatings. The cost of this process is typically covered in four to six months.

“If you have a totally clean system you will reduce the running time on your compressor, and therefore reduce the frequency of oil changes. You’re also not blowing foreign matter, which stops production and results in wasted product,” Hindt said.

Following the deep cleaning, a proprietary disinfectant was applied that kills listeria, salmonella, E. coli to a log reduction of six.

The company said its disinfectant is a registered EPA and NSF product. The unique blend provides many advantages to current market chemicals, including the ability to be applied in unconditioned space, is food-safe with no wipedown required, and does not have any VOCs.

A specialized GreenScreen coating is then applied to the unit, which is onehalf to one micron thick. The GreenScreen protective coating is a photocatalyst of nanocrystals that acts as a “wetting agent” to help water run off in sheets, instead of typical beading that leaves spots.

The coating forms a thin water film, which easily runs off, taking dirt, oils and contaminants with it. With less spotting, easier dirt release and oil removal, reduction in cleaning costs and faster evaporation, the coating provides superior heat transfer by inducing film flow and evaporation. Essentially, the coating prevents the surface from growing bacteria and does not allow anything to stick to it. Therefore, the coils will remain cleaner longer, which makes for easier future cleanings. The coating lasts, on average, one to two years.

The deep cleaning resulted in an eight-degree temperature drop across the coil and increased air flow from 7,500 to 13,900 cubic feet per minute in one coil, and from 8,100 to 14,000 cfm in the second coil. In addition, the post-coil dry-bulb split went from five to 9.8 degrees in the first coil, for a 70 percent improvement, and from 4.8 to 10.7 degrees in the second coil, for a 100 percent improvement.

“After the cleaning, we’re using less horsepower and fewer kilowatt hours to run the coil,” the refrigeration manager said. “The unit runs 40 percent less than before. This has made a big difference. We are able to maintain temperature much more easily.”