Engineered Systems - March 2009 - (Page 37)

www.dedietrichboilers.com Basics For Absorption Chillers 0.1 ATM 5 1 Steam Condensor Chilled water out Cooling water out 3 0.01 ATM Evaporator D e D i e t r i c h BOILERS Makes a Difference Input 219 at www.esmagazine.com/instantproductinfo Solution Heat Exchanger 2 Absorber Chilled water in 4 6 Evap. spray pump Absorber spray pump Purge pump Cooling water in Generator pump FIGURE 1. Single-effect absorption refrigeration cycle. denser) and low-pressure side (expansion pipe, evaporator, absorber). The following component descriptions will include some available options and standard operating parameters: • Condenser. In the condenser, the cooling water absorbs the heat of condensation from the vaporized refrigerant, changing the refrigerant into a liquid. • Expansion. The liquid refrigerant (water) travels from the condenser (0.1 atm) through expansion piping to the evaporator (less than 0.01 atm) during which the liquid refrigerant experiences a drop in pressure and temperature. The liquid refrigerant is discharged into a pan within the evaporator. • Evaporator. The liquid refrigerant (water) is pumped to the chilled water tube bundle top and sprayed on the tube bundle. At the low evaporator pressure (less than 0.01 atm), the liquid refrigerant vaporizes at approximately 38°, removing energy from the chilled water. Most lithium bromide absorption chillers can only produce chilled-water supply temperatures down to 40°. Liquid refrigerant that is not vaporized drops down to the pan and is recirculated. Liquid refrigerant that is vaporized travels from the evaporator to the absorber. • Absorber. The vaporized refrigerant enters a liquid lithium-bromide solution spray within the absorber. The lithium bromide solution absorbs the vaporized refrigerant and the cooling water absorbs the heat of vapor absorption. After the absorption, the liquid lithium-bromide solution takes one of two paths. One path has the liquid bromide solution mixing with a concentrated lithium bromide solution and being pumped to the absorber spray nozzles. The other path has the liquid bromide solution being heated and pumped to the generator/ concentrator. • Generator/concentrator. The lithiumbromide solution enters the generator/ concentrator and is heated by steam or hot water, raising the lithium bromide solution to a temperature where the liquid refrigerant (water) vaporizes and travels to the condenser, completing the refrigerant cycle. The concentrated lithium bromide solution flows down to the absorber, com- w w w. esmag a zin e. c o m 37 http://www.dedietrichboilers.com http://www.esmagazine.com/instantproductinfo http://www.esmagazine.com

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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