Cryogen delivery apparatus and method for regulating the cooling potential of a flowing cryogen

A cryogen delivery apparatus for regulating the cooling potential of a flowing cryogen, said cryogen delivery apparatus comprising:

• a pressure vessel having an inlet for receiving the flowing cryogen within the pressure vessel;
• means for maintaining the flowing cryogen within the pressure vessel so that a liquid-vapor interface is produced within the pressure vessel with a gaseous form of the cryogen having a low cooling potential situated above the liquid-vapor interface and a liquid form of the cryogen having a high cooling potential situated below the liquid-vapor interface;
• conduit means extending into the pressure vessel for delivering the flowing cryogen from the pressure vessel as a two phase flow, the conduit means having a moveable section adapted to move above and below the liquid-vapor interface to form, within the conduit means, a first mass flow rate of the gaseous form of the flowing cryogen and a second mass flow rate of the liquid form of the flowing cryogen;
• actuable movement means adapted to move the moveable section above and below the liquid-vapor interface in an oscillating motion for combining the first and second mass flow rates within the conduit means and thereby forming the two phase flow;
• the oscillating motion having a period defined by a sum of first and second time intervals during which the moveable section is above and below the liquid-vapor interface, respectively, and the two phase flow containing the gaseous and liquid forms of the flowing cryogen in average amounts proportional to the first and second time intervals;
• and
• a controller having registration means for registering at least one set of the first and second time intervals and actuation means responsive to the registration means for actuating the actuable movement means to move the moveable section in the oscillating motion and at the period, whereby increasing the first time interval increases the average amount of the gaseous form of the flowing cryogen contained in the two phase flow and alternately, increasing the second time interval increases the average amount of the liquid form of the flowing cryogen contained in the two phase flow to alternately decrease and increase and thus, regulate the cooling potential of the flowing cryogen as delivered.