An optimization based method has been presented to choose
the optimum concentration of the solvent, cosolvent and refrigerant,
as well as working pressures of a VARS at specified generator,
absorber, condenser and evaporator temperatures. The method
makes it possible to design VARS with complex multicomponent
mixtures and can be used with other multicomponent solvents as
well. In fact, it is also possible to use more than one cosolvent.
The COP of VARS does not decrease significantly when water is
used as a cosolvent with [emim][Ac]-NH3 and [emim][EtSO4]-NH3
combinations. However, there is a substantial reduction of circulation
ratio due to the increase in the difference between concentrations
of strong and weak solutions when water is added as the
cosolvent.
Only a small fraction of water is carried over to the condenser/
evaporator in most cases, particularly at heat source temperatures
of 100 and 120 C.