The amount of condenser subcooling needed is system dependent. The more pressure drops — friction and static — associated with the lines and accessories that carry the liquid in the system, the more need there will be for liquid subcooling to prevent liquid line flash gas. A quick review of the second article in this series (“Why Is Condenser Subcooling Needed?” published in the March 5, 2012, edition of The NEWS) will remind readers of the differences between friction and static pressure drops.
The only sure way to safeguard against liquid line flash gas is to subcool the liquid before it experiences any pressure drops.