Hanbell RC2-F Series, Manual

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a. Economizer by sub-cooler
With this form of operation, a heat exchanger (refrigerant sub-cooler) is used to cool down liquid refrigerant. The
sub-cooling is achieved by injecting a small part of the refrigerant from the condenser into the sub-cooler. The
superheated vapor is pulled into the compressor at the Economizer connection and mixed with the vapor from the
evaporator, which has been already slightly compressed.
The sub-cooled liquid is at condensing pressure with this form of operation, the pipeline to the evaporator does
not therefore require any special features, aside from insulation. The system can be generally applied. Figure 6.24
shows the system with Economizer, sub-cooler.
ECO application by heat exchanger
b. Economizer by flash tank
The liquid sub-cooling is achieved by reducing the boiling point pressure in an intermediate pressure vessel (flash
tank). This physical effect leads to the cooling of the liquid down to the boiling point, due to evaporation of part of
the liquid. To stabilize the pressure of the vessel, a regulator is used which at the same time controls the quantity
of vapor flowing to the Economizer connection of the compressor.
This form of operation gives the most economical thermodynamic performance due to direct heat exchanging. As
the intermediate pressure is reduced to the boiling point temperature, this system should only be used with
flooded evaporators. Figure 6.25 shows the system with Economizer, flash tank.