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Vapor Nucleation in a Cryogenic-Fluid-Dissovled-Nitrogen Mixture During Rapid Depressurization.


pdf icon Vapor Nucleation in a Cryogenic-Fluid-Dissovled-Nitrogen Mixture During Rapid Depressurization. (2030 K)
Yang, J. C.; Cleary, T. G.; Huber, M. L.; Grosshandler, W. L.

Royal Society of London Proceedings. Vol. 455. Series A. 1999, 1717-1738 pp, 1999.

Keywords:

depressurization; cryogenic fluids; fire suppression; pressure reduction; thermodynamics; nucleation; nitrogen

Abstract:

The behaviour of four cryogenic-fluid-dissolved-nitrogen mixtures inside a pressure vessel during rapid depressurization was investigated through experiment. The four fluids studied were CF3I, FC-218 (C3F8), HFC-125 (C2HF5), and CF3Br. Depressurization was achieved by discharging the liquid mixture through a solenoid valve at room temperature. Two initial total vessel pressures were used: (1) ca.2.8 MPa and (2) ca.4.2 MPa. Based on the experimental observations obtained by using a high-speed movie camera, the evolution of dissolved nitrogen was suggested for FC-218, HFC-125 and CF3Br in the cases of initial total pressures of ca.4.2 MPa. For initial vessel pressures of ca.2.8 MPa, vapour nucleation was not observed for any of the four fluid-dissolved-nitrogen mixtures. No degassing was observed for CF3I irrespective of the two initial total pressures. The predicted nucleation pressures based on the classical homogeneous nucleation theory for a binary-component mixture provided qualitative agreement with the observed vapour nucleation inside the vessel.