Better Cooling Via Improved Chillers

April 5, 2002
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Trane says the simpler design of its S-Series (left) has 40% fewer parts than conventional centrifugal chiller designs (right).
WASHINGTON, DC — The Earth Technologies Forum, an international conference on climate change issues held at the Hyatt Regency on Capitol Hill, focused on the solutions that industry can, and is, providing regarding ozone protection and global warming. One important way involves new technology.

Two of the biggest hvacr equipment manufacturers introduced significant new chiller technologies to boost efficiency and help protect the environment.

The Trane Company (La Crosse, WI) showed its new S-Series EarthWise™ CenTraVac™ centrifugal chiller that eliminates the use of oil. The patented machine is said to have a simpler design that offers high efficiency, reduces emissions, and lowers the total cost of ownership.

Carrier Corp. (Syracuse, NY) introduced its Evergreen VSS screw chiller technology, which the company says integrates a variable-frequency motor speed controller, among other design features, and provides an efficiency improvement of as much as 48%.

OIL-FREE CENTRIGUAL CHILLER

Trane’s S-Series technology, which will be available in 2003, incorporates hybrid ceramic ball bearings, HCFC-123, and a direct-drive design in order to achieve oil-free operation.

Jerry Arndt, vice president and general manager of the company’s La Crosse Business Unit, said that the company worked with SKF USA Inc. (Kulpsville, PA) to develop the ceramic bearings for hvacr use. With these bearings, plus the direct drive that eliminates gears, the refrigerant can be used for bearing lubrication, doing away with the need for an oil lubrication system, he said.

With the elimination of oil, the overall parts count is reduced by approximately 40%. Reductions include:

  • Gasketed joints — 20%;
  • Solder joints — 30%;
  • Threaded fittings — 50%;
  • Welded components — 75%; and
  • Flared fittings — 100%.

    The HCFC-123 refrigerant allows for 5% to 20% greater chiller efficiency, and the simple, hermetically sealed design contributes to “sustainable” efficiency, said Arndt.

    It’s built to “maintain the same efficiency as on day one,” he said. There is no oil to contaminate the refrigerant, a common and potentially significant cause of efficiency loss in traditional chillers. Thus, over the life of the chiller, it decreases utility-generated greenhouse gas emissions and reduces operating costs, he said.

    Mike Thompson, marketing manager, noted that “An oil-free machine eliminates oil concerns” — no oil checks, no filter changes, and no oil changes, can translate into reduced maintenance costs.

    Regarding emissions, Arndt said the leak tightness of the chiller means “You may never have to open up the machine. The initial [refrigerant] charge may be the lifetime charge.” To ensure a full charge and peak efficiency, an EarthWise purge is provided to expel noncondensables from the system.

    Trane’s Integrated Comfort™ systems (ICS) and Tracer™ building management system (which will be standard features) will monitor and document chiller operation. Customers will be able to monitor such information as purge run time, condenser and evaporator approach temperatures, real-time energy consumption, and evaporator and condenser temperature differential, said Arndt.

    Arndt related that the technology has been five years in development and has been undergoing testing for four years in the lab. A machine was installed and operating in the Hyatt Regency’s equipment room and was on display for visitors to the Forum.

    Summing up this new development, Arndt remarked, “Doing what’s right for the customer’s bottom line and doing what’s right for the environment are not mutually exclusive.”

    Shown is a color rendering of Carrier’s Evergreen VSS screw chiller.

    VARIABLE-SPEED SCREW CHILLER

    Carrier’s Evergreen VSS technology combines HFC-134a and a high-efficiency Variable Speed Screw (VSS) compressor-based chiller system.

    According to the company, the system incorporates innovations in screw compressor design, advanced materials and manufacturing processes, bearing and lubrication systems, sound and vibration prediction and reduction, advanced variable-frequency motor speed control, power factor improvement, harmonic distortion reduction, and controls integration.

    The technology, which will be available in the second half of 2002, is being offered in the water-cooled chiller market’s largest segment — below 500 tons, the size range that represents 60% of unit volume, according to Doug Bishop, P.E., large chiller global products director.

    “The new Evergreen VSS technology will provide up to 48% better efficiency than comparable tonnage chillers that meet the ASHRAE 90.1 energy standard,” Bishop stated. The system also represents an industry first, he said: “It’s the first time that a variable-frequency motor speed controller has been integrated into a chiller and controls design as a standard product.

    “The result is the optimization of efficiency across the entire operating range, increased reliability, as well as reduced system complexity and cost.”

    Working in conjunction with the United Technologies Research Center (UTRC), Carrier started developing the technology five years ago, with the goal of bringing its commercial customers the highest performance that is affordable on a payback basis.

    Other benefits cited by the company include:

  • Full-load efficiencies below 0.52 kW/ton, to reduce peak demand charges as well as power distribution equipment size requirements;

  • Integrated Part Load Value (IPLV) efficiency of 0.30 kW/ton, which reduces energy usage and cost. “The IPLV is what we’re very excited about,” said Bishop;

  • Use of a nonozone-depleting refrigerant not subject to phaseout;

  • Power factor of 0.99 or better, vs. the industry average of 0.90, to reduce energy transmission losses by nearly 20%;

  • Total harmonic distortion (THD) of less than 5% at the machine vs. at point of common coupling, exceeding the IEEE’s industry standard, to minimize interference to electrical equipment;

  • Sound level below the industry average of 85 dBa; and

  • Integrated, communicating microprocessor controls for system optimization and ease of customer interface.

    The technology is undergoing final operational testing. “Once the testing is complete and our manufacturing process is ready, we’ll bring this technology to market,” he said.

    The new chillers will be “best-in-class in efficiency,” and will “set the standard for innovation and large commercial customer value,” Bishop added.

    The chillers produced with the Evergreen VSS technology will be the latest product addition to the company’s “E3 Solutions” systems. These are systems designed to provide improvement in energy efficiency, environmental impact, and economy.

    As integrated systems (from small packaged systems to large central cooling plants), they deliver low cost of ownership while providing environmentally sound technology, says the company.

    “Through an integrated systems approach, Carrier is offering its commercial customers affordable hvac systems that can deliver real, tangible energy efficiency, with savings that can go right to the bottom line,” said Mary Milmoe, vice president, commercial marketing.

    Publication date: 04/08/2002

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