A commercially available cryogenic direct-acting solenoid valve has been modified to incorporate a rapid-chill feature. In the original application for which this feature was devised, there is a requirement to ensure that at all times, the valve outlet flow consists entirely or mostly of liquid; that is, there is a requirement to minimize vaporization of cryogenic liquid flowing through the valve. This translates to a requirement to chill interior valve surfaces in contact with the flowing liquid.
The net effect of the modifications is to divert some of the cryogenic liquid to the task of cooling the remainder of the cryogenic liquid that flows to the outlet. Among the modifications are the addition of several holes and a gallery into a valve-seat retainer and the addition of a narrow vent passage from the gallery to the atmosphere. Even when the valve is closed, cryogenic liquid flows from upstream of the valve seat, through the holes, and into the gallery, where it circulates around the valve outlet and may be partly vaporized before being vented. As a result, the outlet and nearby valve components are maintained at a temperature close to that of the upstream cryogenic liquid. The rate of flow of cryogenic liquid diverted to the task of cooling is limited by the small diameter of the vent passage.
This work was done by James Richard of Marshall Space Flight Center, Jim Castor of Castor Engineering, and Richard Sheller of Sverdrup Technology, Inc. For further information, access the Technical Support Package (TSP) free on-line at www.techbriefs.com/tsp under the Mechanics category. MFS-32110-1