Trane TRG-TRC011-EN manual Heat exchanger bypass

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period three

Capacity Control

notes

generator

heat exchanger bypass

evaporator

heat exchanger

absorber

Figure 50

As a second line of defense, most absorption water chillers include devices that allow the chiller to recover in the event that crystallization does occur. Some of these devices simply sense impending crystallization, put the chiller through a dilution cycle, and shut the chiller down. Other devices keep the chiller operating while regaining control of the solution temperature and concentration.

The device shown in the figure above is a heat exchanger bypass that allows the chiller to de-crystallize and continue to operate. If crystallization does occur, the heat exchanger begins to be blocked, and the flow of concentrated solution from the generator to the absorber is reduced. Dilute solution, however, continues to flow from the absorber to the generator, resulting in concentrated solution backing up inside the generator.

This backed-up solution will eventually rise enough that the concentrated solution spills over into the bypass pipe and returns directly to the absorber, bypassing the heat exchanger. As a result, the temperature of the solution in the absorber is increased, approaching the temperature in the generator. As this warmer solution flows from the absorber, through the heat exchanger, to the generator, it raises the temperature of the heat exchanger and de-crystallization occurs.

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TRG-TRC011-EN

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Contents Air Conditioning Clinic Absorption Water Chillers Absorption Water Chillers Preface Contents TRG-TRC004-EN Introduction TRG-TRC011-EN Period one Absorption Refrigeration CyclePeriod one Reject heat Heat energy Absorption System Fluids High affinity for water refrigerant Components of the Absorption Cycle Conditions Steam or Hot waterrefrigerant vapor Generator Condenser Refrigerant then flows into the evaporator pan Absorber spray pump Solution Heat Exchanger Dilute Generator pump Equilibrium Chart Heat Solution temperature Period two Absorption Chiller TypesSingle-Effect Chiller Absorber Evaporator spray pump Spray pump Generator pump Double-Effect Chiller Vapor Low Temperature condenser Cooling Generator Water Evaporator Absorber Low-temperature generator pump Generator pump Absorption Chiller Types Direct-Fired Chiller Evaporator High-temperature high-temperature Generatorgenerator pump Chiller/Heater Absorption Chiller Types Changeover Absorption Chiller Types Period three Capacity ControlPeriod three Energy valve Generator Crystallization 10C 37.8C Capacity Control Capacity Control Capacity Control Heat exchanger bypass Evaporator pan Purge System Isolation valve Period four Maintenance ConsiderationsPeriod four Maintenance Considerations Test run with alternate fuel, if dual-fuel burner Maintenance Considerations Maintenance Considerations Corrosion inhibitor and performance additive recommendations Period five Application ConsiderationsCooling-Water Temperature Limitations Combination Chiller Plants 58F Special Considerations for Direct-Fired Chillers Application Considerations Equipment Rating Standards Period six ReviewPeriod six Review Review Review Questions for Period QuizQuiz TRG-TRC011-EN Answers Glossary Glossary Glossary Trane Company