ASHRAE Journal - February 2009 - (Page 26) compared to the propylene glycol secondary systems used today, however systems need to be carefully designed and optimized to ensure they can be produced in an economically viable manner. Additionally, in early 2008 the first low-temperature CO2 cascade system was installed and started in a U.S. supermarket, and this site will be used as a pilot installation to evaluate the technology. Questions still remain regarding system cost compared to today’s HFC direct expansion systems and low-temperature CO2 secondary systems, and laboratory investigations will continue to optimize energy consumption and determine how to best commercialize this technology. Discussion can be implemented with energy consumption better than traditional HFC direct expansion systems by 3% to 12% depending on system type and configuration. Finally, a TEWI analysis demonstrates that these systems are of great importance when reductions in carbon emissions are required. Author’s Note A version of this paper was presented at the IIR Gustav Lorentzen Natural Working Fluids Conference held in 2008 in Copenhagen, Denmark. Calculations have been updated to reflect the latest available GWP values for the HFC refrigerants, U.S. average leak rates for supermarket systems, and carbon production per energy output used in TEWI calculations. References 1. Kazachki, G., D. Hinde. 2006. “Why secondary coolant systems for supermarket refrigeration?” Proceedings from International Refrigeration and Air Conditioning Conference. Paris: IIR/IIF. 2. Melinder, A. 2007. “Choosing secondary working fluid for two common types of indirect system applications.” Proceedings from International Congress of Refrigeration. Paris: IIR/IIF. 3. 2005 ASHRAE Handbook—Fundamentals, pp. 3.15. 4. EIA. 2002. “Updated State-Level Greenhouse Gas Coefficients for Electricity Generation 1998 – 2000.” Washington, D.C.: Energy Information Administration. A basic understanding of the operation of low-temperature CO2 secondary coolant systems has been established through experience with the first pilot installations in the field. A detailed study of the effects of heat gain into the distribution piping network was presented and indicates that careful consideration of these effects is necessary to avoid misleading conclusions when comparing technologies of fundamentally different types. CO2 systems have also demonstrated to have significant installation savings in terms of the amount of required copper piping. An energy analysis was presented, which indicates both low-temperature CO2 secondary and direct expansion systems CRITICAL CLEANING DEMANDS GOODWAY. CHILLER TUBE CLEANERS FOR SMOOTH AND ENHANCED TUBES Goodway’s line of Ream-A-Matics® makes tough tube cleaning a simple, one-person operation. Each machines uses a variety of quick connect brushes and cleaning tools mounted to the tip of a rotating flexible shaft, along with a simultaneous water flush, to remove deposits. Both electric and air powered units are available, as well as units with reversible shaft rotation, a shaft feeder gun, chemical injection, and a 500 PSI power flush. So the next time you need to clean your chiller — clean it the good way. To find out more, call Goodway today at 800-333-7467, or visit us online at www.goodway.com. ELECTRONIC FLOWHOOD FLOWHOOD DIRECT DIGITAL READOUT 25-2500 CFM AUTOMATICALLY CORRECTS FOR AIR DENSITY & BACKPRESSURE CHOICE OF METERS - AIR FLOW ONLY, OR AIR FLOW, VELOCITY, PRESSURE & TEMPERATURE OPTIONS INCLUDE: MEMORY, AVERAGE & SUM TO 2000 READINGS, SEQUENTIAL RECALL, AUTO-READ REPAIR POLICY - TWO WEEK TURNAROUND OR LESS CUSTOM TOPS MADE TO ORDER Shortridge Instruments, Inc. 7855 East Redfield Road • Scottsdale, Arizona 85260 www.goodway.com Innovative Maintenance Solutions (480) 991-6744 www.shortridge.com FAX (480) 443-1267 www.info.hotims.com/23932-10 www.info.hotims.com/23932-23 26 ASHRAE Journal February 2009 http://www.goodway.com http://www.shortridge.com http://www.goodway.com http://www.goodway.com http://www.shortridge.com http://www.info.hotims.com/23932-23 http://www.info.hotims.com/23932-10
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