Cool It Down
Indiana State University Saves on Cooling Towers
Perhaps more than many other industries, today's universities and colleges are beset by dramatically rising costs on every front. One of the areas where overhead can be contained or reduced is in the operation of the chilled water systems that support air conditioning throughout college campuses, specifically the cooling towers.
Like many institutional, office and processing facilities, some colleges are upgrading their cooling towers from the outmoded designs constructed with galvanized steel-sheeted shells to the more advanced models that are based on shells constructed of engineered plastics. These newer designs, particularly those constructed with seamless, HDPE (high-density polyethylene) shells, require much less maintenance, are more energy efficient, and often virtually eliminate costly downtime.
In a recent case, Indiana State University (ISU) began installing the engineered plastic cooling towers at its 190-acre main campus located near the center of Terre Haute in west central Indiana. ISU residences, academic centers, labs, recreational and sports facilities are situated in a park-like community that is separate from the rest of the city and maintains an impressive infrastructure of its own.
Several new cooling towers manufactured by Delta Cooling Towers Inc. have been installed or are planned to support the central and satellite chilled water systems that supply the campus's many academic, student and research facilities.
'Smarter' Systems Choices
"About two years ago we were nearing the completion of a renovated building that became the College of Education," said Mark J. Pupilli, ISU Building and Facilities Manager. "Because the capacity at the central chilled water plant had become nearly exhausted, we decided to install a standalone chiller and also allow the building to be connected to the chilled water plant. So, of course, we were going to need a cooling tower. At the suggestion of one of our suppliers, AC Equipment in Indianapolis, we looked at the Delta plastic cooling towers."
Pupilli explained that these towers offered many features that he liked, and the fact that they were engineered plastic meant that many maintenance issues could be avoided. He was also impressed with the selection of available models, the product quality and a long-term warranty on the double-walled HDPE shells.
After considering the applicable designs, Pupilli decided to purchase a 550-ton tower for the new College of Education building. This model is an induced draft, counterflow design, and features a low pressure drop, self-propelled PVC water distribution system. It also features a direct drive fan powered by a totally enclosed, energy-saving VFD motor. Modular construction allows this tower to be clustered to provide greater cooling tonnage. This model also is relatively light in weight, impervious to UV rays and virtually corrosion-proof.
More recently, ISU received funding to build a satellite chilled water plant to provide some redundancy, as well as much-needed additional capacity in the central chilled water system.
"When we were working on the design of the satellite chilled water plant, we realized that we wanted to utilize Delta cooling towers at that location as well. And so I have two four-cell TM Series towers with a cooling capacity of 2,500 tons at the new satellite chilled water plant. And each of the towers is connected to a VFD. Most of the construction is scheduled for completion in February and the facility is to be turned over to me at the end of March 2011.
The configuration at the satellite plant is two banks of four TM towers, Pupilli said, but that are operated as eight separate towers. "We also have the space to expand the facility in the future," he added. "For example, we could put in another 2,500-ton chiller in there at a later date, and also add two more banks of eight cooling towers."
The TM Series is a selection of induced draft, counter flow design cooling towers that are available in single unit capacities from 250 to 2,000 cooling tons.
"The towers that have been installed are working painlessly," Pupilli said. "We did have a minor fan motor problem, but the treatment we got from Delta has left a very positive impression, because they took care of the matter so quickly. But have never had any problems with the cooling towers, and look forward to many years of trouble-free operation."
Pupilli said the primary maintenance issue with the metal cooling towers was the need to do a lot of coatings and repairs. The main reason for going with the newer, engineered plastic technology was the expectation that those problems would go away.
In addition to the coatings problems Pupilli described, many of the galvanized metal-clad cooling towers require even more expensive repair as well as frequent replacement.
Because of the corrosive nature of water, the chemicals used to treat it, and locations where they are found metal towers will require extensive maintenance and costly repair or replacement bills.