Engineered Systems - December 2008 - (Page 56)

Basics For Refrigerant Chillers condenser water at 85°. Conversely, the chiller energy usage increases as the condenser water temperature increases. At a condenser water temperature of 95°, screw-chiller energy usage increased 21%, and centrifugal chiller energy usage increased 19% as compared to condenser water at 85°. Effect of chilled water temperature difference. The standard chilled water temperature difference is 10°. Chiller capacity increases as the chilled water temperature difference increases (graph 3). At a chilled water temperature difference of 16°, the scroll and screw chiller capacity increases 2.1% as compared to chilled water difference of 10°. Conversely, the chiller capacity decreases as the chilled water temperature difference decreases. At a chilled water temperature difference of 6°, the scroll and screw chiller capacity decreases 1.4% as compared to chilled water difference of 10°. The chiller’s energy usage increases as the chilled water temperature difference increases. At a chilled water temperature difference of 16°, the scroll and screw chiller energy usage increased less than 1% as compared to chilled water difference of 10°. Conversely, the chiller’s energy usage reduces as the chilled water temperature difference decreases. At a chilled water temperature difference of 6°, chiller energy usage decreased less than 1% as compared to chilled water difference of 10°. This analysis is based on keeping the chilled water supply temperature at 44°. Effect of chilled water leaving temperature. The standard chilled water leaving temperature is 44°. Chiller capacity increases as the chilled water leaving temperature increases (graph 4). At a chilled water leaving temperature of 50°, the chiller capacity increased 12.8% for water cooled screw chiller and increased 34.7% for air cooled screw chiller as compared to chilled water leaving temperature of 44°. Conversely, the chiller capacity decreases as the chilled water leaving temperature decreases. At a chilled water leaving temperature of 40°, the chiller capacity decreased 7.2% for water cooled screw chiller and decreased 19.8% for an air cooled screw chiller as compared to a chilled water leaving temperature of 44°. Chiller energy usage decreases as the chilled water leaving temperature increases. At a chilled water leaving temperature of 50°, the chiller energy usage decreased 12% for the water cooled screw chiller and decreased 10.7% for an air cooled screw chiller, as compared to chilled water leaving temperature of 44°. Conversely, chiller energy usage increases as the chilled water leaving temperature decreases. At a chilled water leaving temperature of 40°, the chiller’s energy usage increased 13% for the water cooled screw chiller and 8.1% for the air cooled screw chiller as compared to chilled water leaving temperature of 44°. SUMMARY This article provided basic chiller component descriptions. It is important to note there are many additional chiller components and subsystems that were not discussed but require careful consideration during the design/selection process. A chiller selection analysis was not included due to site-specific limitations and requirements having a substanital impact on final chiller selection. Chiller selection analysis deserves to be a standalone article. Finally, it is important to understand the affect changing chiller operating parameters from the ARI Standard has on chiller operating performance with the following being noted: • It is important to use the IPLV for selecting a chiller with the best energy usage. • Modifying condenser water entering temperature has a higher impact on chiller energy than chiller capacity does. • Modifying chilled water leaving/return temperature difference has a higher impact on chiller capacity than chiller energy usage, when chilled water leaving temperature remains constant. • Modifying chilled water leaving temperature has a substantial impact on chiller capacity and chiller energy usage. ES ! NEW SECURE INSULATION IN A SNAP! INTRODUCING THE NEWLY-IMPROVED KLO-SHURE INSULATION COUPLING SYSTEM ® Installs in seconds! One piece design No metal clamps Superior vapor barrier Supports tubing and secures insulation Eliminates insulation compression Improved finish – no tape, no glue Meets the 25/50 flame spread/smoke developed index Now, installing pipe insulation is a snap with Klo-Shure. Our new one piece design lets the installer insert the Klo-Shure Coupling into channel and lock the top – all in the snap of a ﬁnger. No glue, no tape and no separate parts. Visit www.klo-shure.com to see all of our systems and request a FREE catalog. Learn how Klo-Shure Insulation Couplings can improve your next project! 1-800-839-0891 www.klo-shure.com Sakraida is a senior project manager with Jacbons Consultancy in their Denver office. He is a graduate of Georgia Institute of Technology with a BME and has 25 years of experience designing mechanical systems for laboratories, pharmaceutical prodcution, industrial, and other high-technology facilities. He has extensive experience designing central plant systems (steam, chilled water, hot water) lab utilities (RO, DI, compressed air, N2), and HVAC systems. Reach him at Vincent. Sakraida@jacobs.com. Input 75 at www.esmagazine.com/instantproductinfo 56 En g i neer ed Sy stem s December 2008 http://www.klo-shure.com http://www.klo-shure.com http://www.klo-shure.com http://www.esmagazine.com/instantproductinfo

Table of Contents Feed for the Digital Edition of Engineered Systems - December 2008

Engineered Systems - December 2008 Contents Editor's Note HVAC Challenge Back2Basics Case In Point Commissioning Building Automation HVACR Designer Tips Applications Checklist Lakefront Library: Radiant Systems Meet Natural Ventilation Before (And After) The Flood Basics For Refrigerant Chillers Wire-To-Shaft Efficiency For HVAC Pumps Products Glossary Classifieds Advertiser Index Tomorrow’s Environment

Engineered Systems - December 2008

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