Nexus unit can be used with transcritical CO2 systems.
BAC's Nexus hybrid fluid cooler
Baltimore Aircoil Company (BAC), Jessup, Md., has introduced a modular hybrid fluid cooler, called Nexus, that can be employed with a transcritical CO2 refrigeration system, as well as in HVAC and light industrial applications.
The stainless-steel Nexus, which was unveiled in January at the AHR Expo in Chicago, took five years to develop. It has a modular design that cab range between one and six modules, depending on capacity, noted Paul Noreen, BAC’s director of sales for North America.
When the Nexus fluid cooler is used with a transcritical CO2 system, the CO2 rack is fitted with a brazed plate heat exchanger, explained Noreen. CO2 gas from compressors condenses (or cools, depending on the ambient temperature) in the heat exchanger, with heat removed by water pumped from the fluid cooler on the roof. The fluid cooler in this scenario replaces a condenser/gas cooler on the roof.
The hot water brought back to the roof is cooled in the hybrid fluid cooler, either by water sprayed on a BAC-developed “hCore” heat exchanger or by air when the ambient temperature is less than 60°F.
This scenario is especially suited for a grocery store on the ground floor of a multi-story building, Noreen said. “CO2 pipes can hold 1,200 pounds of pressure, and you probably don’t want those running through somebody’s apartment. It’s a lot safer to run water with 30 pounds of pressure.”
The Nexus system in concert with a compressor rack heat exchanger uses less CO2 refrigerant, he said, adding that the Nexus requires 40% less water than a typical fluid cooler.
In addition, the Nexus, which can also be used inside a building, offers “more capacity in a smaller footprint,” said Noreen. The units are up to eight feet shorter in height, 40% smaller in footprint and 35% lighter in weight than traditional fluid coolers, said BAC,
The modular makeup of the Nexus allows it to be brought to a rooftop in a freight elevator instead of with a crane, he noted.
The Nexus system could also be used in a water-loop application for propane self-contained display cases.
“CO2 pipes can hold 1,200 pounds of pressure, and you probably don’t want those running through somebody’s apartment. It’s a lot safer to run water with 30 pounds of pressure.”
– Paul Noreen, BAC