R04 -- Liquid Overfeed Systems (SI)

Overfeed systems force liquid in excess of the amount evaporated, either mechanically or by gas pressure, through organized-flow evaporators, separate it from the vapor, and return it to the evaporators. Mechanically pumped systems usually pump from a vessel at the connected suction pressure (i.e., low-temperature liquid). Gas-operated systems can be configured to deliver either low-temperature liquid directly like the mechanically pumped system, or subcooled liquid from a controlled pressure receiver at an intermediate pressure. With the latter, the accumulated overfed liquid is transferred from the low-pressure receiver back to the controlled-pressure receiver. Overfeed System Operation Refrigerant Distribution Oil in System Circulating Rate Pump Selection and Installation Controls Evaporator Design Refrigerant Charge Start-Up and Operation Line Sizing Low-Pressure Receiver Sizing