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Absorption Systems

TypesAmmonia Absorption Ammonia water/ hydrogen

Lithium Bromide Absorption Lithium bromide water

- Ammonia Absorption: Is not used in commercial building applications due to the quantities of

ammonia gas. There for normally used where hazards are very slight

- Lithium Bromide: Is commonly used for chilled water systems in commercial + industrial

applications

- Major Components:-Absorber

-Condenser

-Evaporator

-Generator or Concentrator-Pumps

Major liquids Used:

-Water: Used as the refrigerant located in the evaporator

-Lithium Bromide: Used as an absorbent for water vapor found in the absorber

Terminology:

Absorbent: Is the liquid that has the ability to absorb large amounts of water vapor (Lithiumbromide)

Absorber: Component where the vapor is absorbed by the absorbent

Condenser: Component used to condense the water vapor returning from the generator

Evaporator: Component used to absorb heat from the area to be cooled or the chilled watercircuit

Strong Bromide Solution: A solution of lithium bromide and water (Which has a relatively lowconcentration of water vapors). The solution which leaves the generator back to the absorber

Weak Bromide Solution: A solution of lithium bromide and water (which has a relatively high

concentration of water vapors). The solution which leaves the absorber and enters the generator

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Solution Pumps: Used to move system fluids

-Between absorber + Generator

-Circulate water with in the evaporator

High Side: Contains the condenser + Generator - 1.47 PSIA

Low Side: Contains the evaporator + absorber 0.12 PSIA

Heat Exchanger: Used to cool strong solution from the generator before entering absorber aswell as heating up weak solution from absorber before entering the generator

Crystallization: Is when the salt crystals precipitate out of the solution. This is normally with in

the heat exchanger because the strong bromide solution has been dropped below 110F at 65%

concentration

Purge Units:Non condensables are always present in absorption machines. If allowed to

accumulate they can have the following affects-Reduction in capacity (Higher leaving chilled water temp.)

-Crystallization (Because of a reduction in load)

-Corrosion = oxygen + salt solution

Methods of Removal:

-Mechanical vacuum pump

-Non-mechanical continuous purge units

*Note: Crystallization starts at a higher temperature

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