An Investigation into the Mechanics of Joule-Thomson Valve Plug Formation
A. study was undertaken to examine the phenomenology of plug formation via contaminant condensation in sonic flow Joule-Thomson (J-T) orifices. An apparatus was constructed which allowed plug formation to be visually observed. The cold end of the apparatus consists of a pre-cooler, a counterflow heat exchanger and the J-T expander. Because this is the normal configuration of a cascaded J-T refrigerator cold end, the knowledge gained is directly applicable to existing systems. The test apparatus uses nitrogen gas as the refrigerant and water vapor as the contaminant. Plug formation in a glass J-T expansion valve was observed through a microscope and photographically documented. It was discovered that, for the straight sonic orifices used during these tests, plug formation occurred only in the orifice itself. No contamination condensation was observed on the orifice faces. Mechanisms are proposed which describe the observed characteristics of the plug nucleation and growth.
KeywordsEntropy Enthalpy Drilling Hydride Refraction
Unable to display preview. Download preview PDF.
- 1.K. Karperos, Operating Characteristics of a Hydrogen Sorption Refrigerator, Part I: Experiment Design and Results, Proceedings of the 1986 Cryocooler Conference, Easton, Maryland, Sept. 25–26, 1986.Google Scholar
- 3.K. Hedegard, G. Walker, and S. Zylstra, Temperature Sensitive Variable Area Flow Regulator for Joule-Thomson Nozzles, Proceedings of the 1986 Cryocooler Conference, Easton, Maryland, Sept. 25–26, 1986.Google Scholar
- 4.J. M. Lester and B. Benedict, Joule-Thomson Valves for Long Term Service in Space Cryocoolers, Spec. Pub. 698, National Bureau of Standards, Boulder, Colorado (1984), p. 257.Google Scholar
- 5.C. K. Chan, private communication, April 1987.Google Scholar
- 6.A. H. Shapiro, “The Dynamics and Thermodynamics of Compressible Fluid Flow,” Ronald Press Co., New York (1953).Google Scholar