Special Features of Water-Lithium Bromide Solution
Here are some special features of the water and lithium bromide in an absorption refrigeration system:
1) Lithium bromide has great affinity for water vapor, however, when the water-lithium bromide solution is formed, they are not completely soluble with each other under all the operating conditions of the absorption refrigeration system. Because of this, the designer must take care that such conditions would not be created where crystallization and precipitation of the lithium bromide would occur.
2) The water used as the refrigerant in the absorption refrigeration system means the operating pressures in the condenser and the evaporator must be very low. Even the difference of pressure between the condenser and the evaporator must be very low. This can be achieved even without installing the expansion valve in the system, since the drop in pressure occurs due to friction in the refrigeration piping and in the spray nozzles.
3) The capacity of any absorption refrigeration system depends on the ability of the absorbent to absorb the refrigerant, which in turn depends on the concentration of the absorbent. To increase the capacity of the system, the concentration of absorbent should be increased, which would enable absorption of more refrigerant. Some of the most common methods used to change the concentration of the absorbent are: controlling the flow of the steam or hot water to the generator, controlling the flow of water used for condensing in the condenser, and re-concentrating the absorbent leaving the generator and entering the absorber.