What is the method of dry expansion oil circuit in the chiller.?

The alternative method of returning oil from the evaporator to the compressor is to keep it moving, by ensuring a minimum continuous fluid velocity in all parts of the circuit. This is termed the dry expansion circuit this dynamic circulation method is the decisive

Factor in the design of nearly all halocarbon evaporators, the exceptions being ‘flooded’ evaporators. The critical section of the circuit is where there is no liquid refrigerant left to help move the oil, i.e. the evaporator outlet and the suction pipe back to the compressor. Entrainment velocities of5–7 m/s are required to ensure that oil droplets will be carried back by the dry refrigerant gas to the compressor. The principle of continuous fluid velocity means that the evaporator will be in a continuous circuit. This does not imply that it has to be one pipe, since many pipes may be arranged in parallel to get the required heat transfer surface, providing the minimum velocity criteria are met.