Daikin introduced an integrated water-side economizer (WSE) for its Pathfinder® Air-cooled Screw Chiller. The WSE, providing what is commonly known as “free cooling,” uses outdoor air to naturally cool water and other process fluids, reducing compressor work and increasing chiller efficiency. The Pathfinder with Free Cooling also operates without needing water from a cooling tower. This drastically cuts water use, as well as costs for water, sewer, and chemical treatment.
“Water availability is starting to become a widespread problem,” said Hugh Hudson, data center market manager, Daikin Applied. “For many organizations, water conservation is part of their sustainability efforts. And some facilities are in areas with water restrictions. By omitting a cooling tower or evaporative cooling system, free-cooling chillers put less stress on municipal infrastructure and the environment.”
Most free-cooling systems require two separate pieces of equipment, a chiller and dry cooler, along with a layer of controls for coordination. By adding an on-board economizer to the Pathfinder, both tuned at the factory to optimize control and performance, the Daikin technology decreases installation and commissioning times, and related expenses. Overall, the Pathfinder with Free Cooling can trim upfront capital costs by as much as 40% compared to traditional economizer applications.
The integrated waterside economizer (Free Cooling System) option adds fluid-to-air heat exchanger coils in series with the airflow of the primary chiller condenser coils in order to reject heat to the outdoor air without the need for vapor compression cooling. This type of cooling is possible when the outdoor air temperature is colder than cooling fluid temperature requirements.
The integrated layout is also more compact, reducing air-flow clearances and interconnecting pipes. Plus, the chiller’s pipe headers are made of multi-layer polypropylene to eliminate corrosion and contaminants while trimming weight and the load on a building’s roof. They are located on the exterior of the unit for service and maintenance access, and they are also removable, allowing the entire unit to fit in a standard shipping container.
Efficient cooling in a smaller footprint allows for larger facility scale and higher power densities. It enables code-compliant designs as well, helping meet ASHRAE 90.1 and 90.4 standards, and other regional and local codes.
“The Pathfinder with Free Cooling is particularly suited to data centers, which are rapidly growing in number, size, and power density,” Hudson said. “The chiller-WSE combination simplifies construction, which ultimately lowers cost while decreasing the risk of installation errors and schedule overruns.”
The Pathfinder functions in three different modes—free cooling, mechanical, and hybrid—to optimize energy performance and, for a data center, improve power usage effectiveness (PUE). And at low ambient temperatures, the WSE coils reject the heat, allowing the chiller compressors to shut down, eliminating power draw entirely. Daikin’s proprietary microchannel fluid coil design also allows the unit to operate at a lower air pressure drop, which decreases the energy required to run the fans, furthering efficiency and contributing to a faster payback.
When the unit operates in high ambient temperature conditions, the Pathfinder uses Daikin’s Variable Volume Ratio (VVR®) technology and a variable frequency drive to maximize efficiency, resulting in substantial cost savings for building owners over the life of the equipment. This is the first factory-packaged air-cooled chiller that provides both an integrated WSE and VVR compressor technology.