Keeping Cool With Plastic
May 9, 2011
On what would normally have been a mild September day, Southern California was blasted by a record-breaking heat wave with temperatures spiraling upwards to 116°F in the Los Angeles basin. The heat was far above the normal highs, which would typically be in the mid-70s.
Naturally, the fierce heat combined with high humidity would be a considerable challenge to maintaining the air conditioning in buildings of all types, but particularly in office buildings, where tenants can be sensitive to uncomfortable temperatures.
For the tenants of an LAX Airport Center office building, the cooling tower that works in conjunction with the building’s HVAC chillers had just been replaced. And it maintained proper temperature for the offices.
“This was a very fortunate situation,” said Pat McGuire, sales manager of Centrifugal Technologies Inc. of Azusa, Calif., an air conditioning specialist who worked with L.A.T. Investment Corp. on the new tower design and specifications.
The 16-story, 500,000-square-foot structure built in 1982 was originally equipped with injector cooling towers.
“This was a conventional system design back in the 1980s,” McGuire explained, “but over time the injectors can corrode and clog, causing performance and maintenance problems.”
TO REPLACE OR UPGRADE?As a mechanical contracting HVAC specialist, McGuire often evaluates newer cooling tower designs for both new and replacement installations.
“We felt that a newer type of cooling tower, designed with a shell of engineered plastic, would be more efficient and less maintenance-intensive for the application than simply replacing the old injector system with a new one,” McGuire said.
The engineered plastic cooling tower from Delta Cooling Towers had been used in industrial and commercial applications of many types because of its inherent resistance to corrosives, as well as high-efficiency features.
Because the building was located near Los Angeles International Airport, it was exposed to the corrosive effects of industrial effluents, jet fuels, and the nearby Pacific salt air. Those corrosive effects, as well as prevailing high humidity, were contributing to the increasingly waning performance of the building’s old injector cooling tower system, thus the attention given to the plastic model.
“I like the Delta design,” McGuire said. “The double-wall plastic shell is impervious to UV light, pH or corrosives, so it’s very low in maintenance. The tower operates well in high humidity. The shell has a 15-year warranty. Also, I think it’s got strong price advantages.”
The model that McGuire recommended was a single, 500-ton Delta TM series cooling tower to replace the old injector tower. The TM Series is an induced draft, counterflow design that is modular and capable of providing from 250 to over 2,000 cooling tons.
The cooling tower fan runs off a variable-speed drive, so the fan runs slower, consumes less energy and creates less wear and tear on the motors, according to the manufacturer. In office building applications, the variable-speed fan gradually starts in the morning as the weather warms, typically running at 30 percent until it shuts off in the evening.
GOING WITH TECHNOLOGYStill, there was the matter of convincing building management and ownership that switching to a new cooling tower technology was the right thing to do.
“Centrifugal Technologies had serviced our cooling towers and chillers for about 20 years, so we had a lot of faith that Pat’s recommendation was solid,” said Barron Lowery, the building’s chief engineer. “The main factor that convinced us that we should go with the engineered plastic cooling tower was the avoidance of unhappy tenants. Plus, we learned that if we replaced the old cooling towers with the newer technology, we would have lower operational costs and could avoid the need to replace the tower for quite a bit longer.”
Lowery said that because the new tower promised higher efficiency, cooling would be greatly improved. Therefore he would avoid the need to engage the backup system during peak demand periods in the middle of the day.
“That would save us money and save on energy consumption. So, it was the green thing to do, and we decided to go with it,” he said.
And a few weeks after installation, when the uncharacteristic heat wave hit the Los Angeles basin, the new cooling tower was put to an extreme test.
“It performed very well,” Lowery said. “In fact, I would say it exceeded everyone’s expectations. And the tenants all stayed perfectly comfortable.”
EDITOR’S NOTE: This story was supplied by Delta Cooling Towers (www.deltacooling.com), who noted it was prepared by Ed Sullivan, a technology writer based in Hermosa Beach, Calif.
Publication date: 05/09/2011