City Campus cooling tower project enters final phase

· 4 min read

City Campus cooling tower project enters final phase

Water rains down inside a cooling tower by UNL's City Campus utility plant at 14th and Avery streets. Construction of a new cooling tower to replace an old model will begin May 27.
Troy Fedderson | University Communications
Water rains down inside a cooling tower by UNL's City Campus utility plant at 14th and Avery streets. Construction of a new cooling tower to replace an old model will begin May 27.

A major upgrade to UNL’s City Campus heating, ventilation and air conditioning system enters its final phase this week.

Designed to increase the efficiency, redundancy and capacity of the campus heating/cooling system, the project is replacing two of the three cooling towers at the 14th and Avery streets utility plant. The first redesigned tower went online in fall 2013, while the second will be rebuilt this summer and start operating in the fall.

“The cooling tower system at the plant has been troubled with reliability issues for years due to the age and condition of the infrastructure,” said Charlie Griesen, utility project manager for Facility Planning and Construction. “This is the final phase of a multi-year effort to replace key components that the campus relies on for air conditioning of buildings.”

The City Campus system includes three cooling towers that remove heat from water used in the HVAC system. Inside the towers, nozzles spray water (up to 69,000 gallons per minute for all three towers) evenly through a specialized plastic material that is six feet thick. As the water flows through grooves in the plastic, giant fans draw air up and through the system. The upward flowing air helps draw heat out of the descending water, which pools in a concrete water basin before being drawn back into the HVAC loop.

Griesen said the new cooling towers use a plastic material with a counter-flow design, which allows for more efficient removal of heat.

“The cooling tower is designed so that water leaving a counter-flow tower is 10 to 15 degrees cooler than when it entered,” Griesen said. “During the summer, water enters cooling tower at about 90 degrees Fahrenheit and exits at 75 degrees. In the winter, the water can leave the tower as cool as 50 degrees.”

The new design also includes four cells in each tower that can be individually operated to meet demand or to allow for repair/maintenance. Previously, the two towers ran on an all-or-nothing design, which required a complete shutdown for repairs.

When complete, the newest tower, located by the sidewalk on 14th Street, will look different than the other two cooling units. Griesen said, where a corrugated fiberglass product was previously used on tower exteriors, UNL has opted for a double-wall design that will look more like architectural siding. The exterior wall will also extend to what was previously an exposed rail at the top of the tower to hide mechanical equipment.

“As this tower is the most visible, we decided to dress it up a bit,” Griesen said. “It’s definitely going to have more of an architectural look and feel.”

The next phase of work on the new $2.5 million tower is scheduled to begin May 27. This part of the project will include a temporary lane closure on 14th Street. A center turn lane will be used to allow traffic to continue to flow south toward Vine Street.

The tower will be brought online in the fall after it is connected to water and power lines.

For more information on the project, click here.

This rendering shows the exterior design for the new cooling tower by the City Campus utility plan. The new structure will feature a double-wall, fiberglass product that looks like architectural siding. Previous towers have used a corrugated fiberglass product.
Courtesy photo
This rendering shows the exterior design for the new cooling tower by the City Campus utility plan. The new structure will feature a double-wall, fiberglass product that looks like architectural siding. Previous towers have used a corrugated fiberglass product.
UNL has previously used a corrugated fiberglass material (left) on the exterior of its cooling towers. The new tower will use a double-wall fiberglass product that looks like architectural siding (right).
Troy Fedderson | University Communications
UNL has previously used a corrugated fiberglass material (left) on the exterior of its cooling towers. The new tower will use a double-wall fiberglass product that looks like architectural siding (right).
Inside a cooling tower, nozzles like this one evenly spray water across the top of the tower and onto a plastic material that helps remove heat.
Troy Fedderson | University Communications
Inside a cooling tower, nozzles like this one evenly spray water across the top of the tower and onto a plastic material that helps remove heat.
Water inside UNL's newest cooling towers flows through a plastic material that features a counter-flow design. The product is more efficient, helping remove additional heat from water in the HVAC system.
Troy Fedderson | University Communications
Water inside UNL's newest cooling towers flows through a plastic material that features a counter-flow design. The product is more efficient, helping remove additional heat from water in the HVAC system.
Computer screens inside the City Campus utility plant show how cooling towers (pictured) and other parts of the campus HVAC system are operating. The new tower design features four cells (represented by each fan) and allows for parts of the tower to be shutdown for repairs.
Troy Fedderson | University Communications
Computer screens inside the City Campus utility plant show how cooling towers (pictured) and other parts of the campus HVAC system are operating. The new tower design features four cells (represented by each fan) and allows for parts of the tower to be shutdown for repairs.

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