Credit: Rosser
Architects and engineers working at Armstrong American State University in Savannah, Ga., have installed an aesthetically pleasing ceramic water-cooling tower for the school’s student Union and Memorial College Center that they say will provide heating, ventilation and air conditioning for decades.
The basic technology behind this system is fairly low tech: Water is sprayed over ceramic fill material resulting in evaporative cooling. The cooled water is circulated through a heat exchanger that is connected to a separate air circulation system. In the case of AASU’s 400-ton system, a single large fan circulates water over a grid of 25,000 tiles.
The first big difference between the ceramic-tile fill system and a typical institutional HVAC PVC-fill system is the appearance of the equipment, itself. Instead of the large and unsightly steel and PVC box systems found on top or outside of big office buildings and hospitals, designers can create architectural towers that nicely blend into the lines of a building and landscaping. As apparent above, the AASU cooling tower turns the set of water streams into something that looks more like a fountain.
But there are also some dollar-and-cents reasons why these types of cooling towers may – or may not – make sense. One consideration is the time horizon of the building owner. Short term investors may be averse to the extra capital cost (some estimates peg the initial cost of a ceramic tower at four-times a regular air-cooled HVAC system). On the other hand, those in it for the long haul, such as a university or hospital, can justify the initial expense of the towers for several reasons.
First, the ceramic systems are rugged and impervious to the elements and designed to last 30-40 years. This contrasts with typical air-cooled HVAC systems that require regular maintenance and still must be replaced every decade or so because the fill clogs, UV rays degrade the tubing and moisture corrodes the metal surfaces.
Gary Drummond of Tower Engineering Inc., the cooling tower manufacturer that assisted Rosser architects with the AASU project, says ceramic systems maintain 100% thermal performance for life and are also immune to freeze-thaw cycles and are impervious to biological growth and chemical attack.
Drummond says he and others at the company have experience constructing these towers since 1968. The technology actually began in 1947 and one of the recent innovations is a change to a tile-grid system such as the one used in AASU instead of having the water pass over brick-like pieces. “We call it high-performance ceramic fill because the tile system is much more efficient because of increased wetted surface area and less static pressure requirement. We also can use TEI’s variable-speed fan motor system to provide even more savings with less horsepower and less maintenance,” he says.
Rosser’s Chuck Hanning, who has been involved with the school project for about two years, tells the AASU student newspaper that standard air-cooled chillers require 1.2 to 1.3 kilowatts of power per ton of cooling, compared with ceramic towers that only require 0.5 to 0.7 kilowatts per ton.
A final plus for ceramic fill cooling towers is design freedom. Rosser and TEI tout that these systems easily can be designed around a number of parameter besides appearance, including an ability to withstand hurricanes and earthquakes.
Drummond says TEI guarantees the thermal performance of the company’s ceramic fill systems for 25 years. He also notes the tiles and blocks used in the company’s towers aren’t extraordinary in themselves. He says they are just hard-burned clay that can be readily supplied through global brick making facilities.