Abstract: Control system capable of controlling the refrigeration capacity of a refrigeration system adapted for cooling a fluid medium, the refrigeration system being of the type including a refrigerant; an absorbent having an affinity for the refrigerant; an evaporator for bringing the refrigerant into heat transfer relationship with the fluid medium, the evaporator having an inlet for receiving the fluid medium to be cooled in an outlet for discharging cooled fluid medium; an absorber in communication with the evaporator for removing refrigerant vapor therefrom; means for supplying a concentrated absorbent-refrigerant solution to the absorber; means for cooling the absorber to maintain the pressure therein below the pressure in the evaporator whereby refrigerant vapor migrates to the absorber to combine with the concentrated solution to produce a dilute solution; a concentrator for removing a portion of the refrigerant from the dilute solution for recirculation to the evaporator and for providing the concentrated so