Engineered Systems - March 2009 - (Page 46)

Basics For Absorption Chillers age potential and will allow projects exclusively using natural refrigerants to claim the credit without using the Enhanced Refrigerant Management formula. Absorption chillers can be a key component in meeting the USGBC strategy of reducing atmospheric damage. ABSORPTION CHILLER ENERGY EFFICIENCY Absorption chiller energy efficiency is based upon fuel consumption per ton cooling while motor driven vapor compression chiller energy efficiency is based upon kW/ton cooling. The COP is a method for determining overall chiller energy performance. For absorption chillers, the COP formula is: COP = Eu / Ea where: Eu = useful energy obtained (Btuh) Ea = energy used (Btuh) For motor-driven chillers, the COP formula is: COP = 12 KW/ton x 3.412 Per manufacturer supplied information, the coefficient of performance range for the different absorption chiller types are as follows: Absorption chiller type COP range Hot water or steam single-effect chiller . . . . . . . 0.60 to 0.75 Hot water or steam double-effect chiller . . . . . . 1.19 to 1.35 Direct fired double-effect chiller . . . . . . . . . . . . . . 1.07 to 1.18 Looking at the COP ranges, the single-effect chiller is the least energy-efficient absorption chiller type with the hot water, steam, and direct-fired, double-effect absorption chillers being almost twice as energy efficient. The hot water and steam double-effect absorption chillers are the most energy efficient absorption chillers, but how do they compare to motor driven vapor compression chillers? The two motor-driven vapor compression chillers being utilized for energy efficiency comparison are the water cooled rotary screw chiller and the water cooled centrifugal chiller. Per manufacturer supplied information, the water cooled rotary screw chiller has a COP range of 3.90 to 5.40 while the water cooled centrifugal chiller has a COP range of 7.00 to 8.79. The result is that motor driven vapor compression chillers are 4 to 7 times more energy efficient than absorption chillers. This leads to a question: Why would you want to use an absorption chiller? KEEPING THE COOL IN SCHOOL WITH TRANE RENTAL SERVICES. Distracted students, uncomfortable teachers, and missed instructional days are uncool. Trane Rental Services knows how important proper temperature and air quality is in educational institutions. We can make sure that your facility is up and running during the most trying times. With depots located across the We provide the following rental equipment: Americas, local service providers, and 24/7 corporate support, Trane Rental Services is your go to resource for: • Seasonal capacity needs • Planned service work • Facility expansions & renovations • One-time events • Disaster contingency planning • Chillers • AC units • Cooling towers • Air handlers • Power generators • Electrical cable • Transformers • Heaters • Pumps Call us at 1-800-755-5115 or visit us at www.trane.com/rentalservices © 2009 Trane. All rights reserved. Input 200 at www.esmagazine.com/instantproductinfo 46 En g i neer ed Sy stem s March 2009 http://www.trane.com/rentalservices http://www.trane.com/rentalservices http://www.esmagazine.com/instantproductinfo

Table of Contents Feed for the Digital Edition of Engineered Systems - March 2009

Engineered Systems - March 2009 Contents Editor’s Note Back2Basics Case In Point Commissioning Building Automation HVACR Designer Tips Application Checklist Teaching An Old School New Tricks Basics For Absorption Chillers A New Haven For Sustainable Schools Glossary Classifieds Advertiser Index Tomorrow’s Environment

Engineered Systems - March 2009

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