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TRG-TRC011-EN 13
period one
Absorption Refrigeration Cycle
notes
Inside the absorber, the refrigerant vapor is absorbed by the lithium bromide
solution. As the refrigerant vapor is absorbed, it condenses from a vapor to a
liquid, releasing the heat it acquired in the evaporator. This heat, along with the
heat generated during the process of being absorbed, is rejected to the cooling
water that is circulated through the absorber tube bundle. Absorption of the
refrigerant vapor creates a low pressure area within the absorber. This lower
pressure, along with the absorbent’s affinity for water, induces a continuous
flow of refrigerant vapor from the evaporator.
Maximum surface area is provided by spraying the solution over the tube
bundle. This also provides maximum heat transfer to the cooling water. The
absorber spray pump mixes concentrated absorbent solution (returning from
the generator) with dilute solution (from the bottom of the absorber) and
delivers this intermediate solution to the absorber sprays.
There are two reasons for using an intermediate solution rather than a
concentrated solution in the absorber sprays. First, for effective tube wetting, a
greater quantity of solution is required than is available from the generator.
Therefore, dilute solution is mixed with the concentrated solution to increase
the total quantity of solution being sprayed over the tube surfaces. Second, if
concentrated solution were sprayed directly upon the absorber tube bundle, it
would be subjected to temperatures that could cause it to crystallize—a
solidification of the bromide salt. Therefore, the concentration is reduced by
mixing it with dilute solution.
cooling
cooling
water
water
refrigerant
refrigerant
vapor
vapor
concentrated
concentrated
solution
solution
intermediate
intermediate
solution
solution
absorber
absorber
spray pump
spray pump
dilute
dilute
solution
solution
absorber
absorber
Figure 16