Plate Shell Heat Exchanger + Vahterus External Separator
In the refrigeration industry, evaporators are mostly used for cooling down liquids or for condensing gases. The evaporation side of the unit can be operated either in flooded or direct expansion mode. Flooded type evaporators are typically used with applications using ammonia as refrigerant. Systems with flooded circulation of the refrigerant can be designed with external and internal circulation. External circulation always has a separator above the evaporator and external piping between the separator and the evaporator. With internal circulation the heat exchanger is integrated into the separator shell with no external piping (see Combined Manual, Private Area).
PSHE&VES-units have been developed to reduce the dimensions of the separator by using a specially designed droplet separator inside the vessel (demister). In the separator there is volume available for liquid storage during stand still or for other applications in the total system. In this way, the unit may be used in applications with air cooled or evaporative condensers and with a high pressure float valve as the expansion device. In these systems, the refrigeration charge in the condenser could be rather high compared with a water cooled condenser. (Of course these units can also be used with water cooled condensers.)
Because of the specially designed separator with demister the separator vessel is much smaller compared to more common separators and increases the potential acceptance of the natural refrigerant NH3 even further. The PSHE&VES-units gives high performance for larger temperature differences and high surface load.
