Liquid Refrigerant Receivers are designed to hold excess liquid that would otherwise back up in the Condenser Coil and essentially reduce the size of the Condenser Coil.
During pump down, Receivers also act as a holding tank.
Receivers in standard HVAC&R units will have the IN connection as free flowing and the OUT connection will have a long dip tube which goes up to the bottom level of the vessel.
But machines designed with reversible cycles also called as Heat Pumps or Heating and Cooling air-conditioners need a change in Liquid Refrigerant Receiver Design.
Receivers for the Heat Pump are designed with both IN and OUT connections having a long dip tube of the same length going up to the bottom of the vessel.
This design makes sure that in both cases (Heating or Cooling) the liquid line will receive liquid refrigerant only.