Civil Engineering Reference
In-Depth Information
Fig. 12.5
An absorption refrigeration system
be installed to keep the temperature of the absorber as low as possible and to
allow a strong refrigerant-absorbent solution.
• Upstream of the condenser (point 2), the refrigerant vapor must be retrieved
from the liquid solution (as a result, the strong refrigerant-absorbent solution
becomes a weak solution) before entering the condenser. This is an endothermic
process and consequently a thermal input power, which represents the main
input of the system, is needed. Steam or waste heat are generally used; natural
gas or other fuels can be burned to provide the heat source. The choice of heat
source is determined mainly by cost.
The refrigerant vapor passes to the condenser and the remaining solution,
which is a refrigerant weak solution, flows back into the absorber tank through a
valve without entering the condenser.
The commonest cycles use lithium bromide-water solution in which water is the
refrigerant and lithium bromide the absorbent; pressures are always lower than the
atmospheric value. Another type of absorption system uses ammonia-water solu-
tion in which ammonia is the refrigerant and water the absorbent.
