1) Boiling temperature of water is a function of pressure. At lower pressure it boils at lower temperature.
2) Lithium Bromide salt has the property to absorb water due to its chemical affinity. It is soluble in water. As the concentration of Lithium Bromide increases its affinity towards water increases and as its temperature increases its affinity decreases.
3) Water Hash cools to about 4″C at an absolute pressure of 6 mm Hg. produces the refrigeration effect by picking up the latent heat from the external Chilled water line. The vaporized refrigerant needed to be liquefied by absorbed heat of dilution, is removed by using cooling water.
The water lithium bromide absorption system is used in these machines. This is a based on three basic facts – The Lithium Bromide is heated by an external heat source. Refrigerated vapour (water) leaves Lithium Bromide concentrated solution. The refrigerated vapour is condensed using external cooling water in the condenser.
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This operation is for single stage absorption cycle. In the double stage the generation of refrigerant vapour is generated in the first stage acting as the heating source for the second stage.
These machines are used from 70 to 1400 TR.
Advantages
(a) Easy maintenance less moving parts, noise free, less vibration.
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(b) Less electricity is needed
(c) Low operating cost
(d) Restriction on the manufacture of chlorofluro carbon which is used in vapour compression cycle
(e) Low system cost.
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(f) Cold and hot water both can be obtained.
(g) No standby is required.