Founded in 1837 and named after the only physician to sign the U.S. Constitution – Benjamin Rush – Rush University Medical Center (RUMC) is now Chicago's second-largest hospital with multi-story buildings that dominate the city's medical district. But that prestigious location posed problems when RUMC's 11-story Professional Building 2 needed to replace two aging centrifugal chillers. It appeared the only alternative was to move a crane down a crowded street to lower new chillers through the roof. But some simple surgery made it possible for Smardt split-shell chillers with Danfoss Turbocor® compressors to simply take an elevator up to the penthouse mechanical room, a solution that cut installation costs while boosting energy savings.
“The professional building was using two fixed-speed 300-ton water-cooled centrifugal chillers,” said Mike Scalleta, Mechanical Systems Manager at RUMC. “They were installed when the building was built in the 1970s. Consequently, the old centrifugal chillers were using twice the energy compared to today's more efficient variable-speed chillers. It was time for them to go. The problem was we'd have to cut open the mechanical room and use a crane to drop in conventional replacement chillers. Fortunately, we learned Smardt had a solution. Their split-shell Smardt chiller design with compact Danfoss Turbocor centrifugal compressors could be taken apart to fit into our freight elevator. Using the elevator would minimize building disruption and reduce installation costs, and the efficiency of a variable-speed Smardt chiller would dramatically cut our energy costs."
RUMC replaced two aging fixed-speed 300-ton water-cooled centrifugal chillers (shown here) with energy-efficient Smardt split-shell chillers with Danfoss Turbocor compressors, reducing installation costs and saving $75,000 in annual operating costs.
As the worldwide leader in oil-free magnetic bearing chiller technology, Smardt sought to significantly reduce installation costs and boost efficiency – helping the overall bottom line.
Split-shell Chiller Fits Big Efficiency in a Tight Space
The energy efficiency of the Smardt chiller turned out to be a big plus that fit into a small space. According to Bullock, Logan and Associates’ Curt Bullock, Jr., a Chicago representative for Smardt, the difference between the Smardt chiller and the old centrifugal chiller was night and day. Bullock calculates that when the old chiller was new, its integrated part-load value (IPLV) was 0.716 kW/ton but used oil-lubricated bearings. Because oil fouls heat exchanger tubes over time, actual efficiency was worse.
“In comparison, the IPLV of the Smardt chiller is 0.315 kW/ton – 57% more efficient," said Bullock. "That's partly because there are no oil-related heat transfer losses and no mechanical-bearing friction losses. Another energy-saving feature is the compressor's ability to adjust automatically to off-design conditions. The Danfoss Turbocor TT400 compressor can turn down capacity to 10% of its total capacity. By automatically matching capacity to the load, the compressor reduces its speed, which also reduces energy consumption.”
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