A CFD Study on Two-Phase Frozen Flow of Air/Water Through a Safety Relief Valve
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Moftah Alshaikh
Abstract
The air-water two phase critical flows through a safety relief valve commonly used in the refrigeration industry is examined with particular emphasis on the prediction of the critical mass flowrates using CFD based approaches. The expansion of the gas through the valve and the associated acceleration is coupled to the liquid phase and results in changes to the velocity slip with the possibility of influencing the choking conditions and the magnitude of the critical mass flows. These conditions are poorly reported in the literature for safety valves. This paper presents a study where the ability of established two phase multi-dimensional modelling approaches to predict such conditions are investigated. Comparison with the simplified mixture model will show that this model tends to underestimate mass flowrates for medium to high liquid mass fraction. However, the two fluid model can adequately account for the thermal and mechanical non equilibrium for these complex flow conditions with the use of simplified droplet sizing rules.
References
1. Alger, T.W., 1978. Droplet phase characteristic in liquid-dominated steam-water nozzle flow, PhD Thesis, Lawrence Livermore Laboratory, University of California.Search in Google Scholar
2. Darby, R., July 2004. On two-phase frozen and flashing flows in safety relief values: Recommended calculation method and the proper use of the discharge coefficient. Journal of Loss Prevention in the Process Industries 17, 255–259.Search in Google Scholar
3. Dempster, W.M., Lee, C.K., Deans, J., 2006. Prediction of the flow and force characteristics of safety relief valves, Proceedings of PVP2006-ICPVT-11 2006 ASME Pressure Vessels and Piping Division Conference, July.Search in Google Scholar
4. Dempster, W., Elmayyah, W., 2013. Two phase discharge flow prediction in safety valves. International Journal of Pressure Vessels and Piping, 110, 61–65. ISSN 0308–0161.Search in Google Scholar
5. Elmayyah, W., May 2010. Theoretical and experimental investigations of multiphase flow in safety relief valves PhD Thesis, Department of Mechanical and Aerospace Engineering, University of Strathclyde Glasgow.Search in Google Scholar
6. Fluent 6.3 User Guide, 2006.Search in Google Scholar
7. ISO standard, 2010. Safety devices for protection against excessive pressure Part 10: Sizing of safety valves for gas/liquid two-phase flow, ISO-4126-10.Search in Google Scholar
8. Kolev, N.I., 2007. Multiphase Flow Dynamics 2 Thermal and Mechanical Interactions, 3rd ed, Springer, ISBN 978-3-540–69834.Search in Google Scholar
9. Lemonnier, H., Camelo-Cavalcanti, E.S., 8–11 Aug 1993. Droplet size and velocity at the exit of a nozzle with two component near critical and critical flow, National Heat Transfer Conference; Atlanta, GA (United States).Search in Google Scholar
10. Leung, J.C., 1986. A generalized correlation for one-component homogeneous equilibrium flashing choked flow. AIChE Journal.Search in Google Scholar
11. Manninen, M, Taavassalo, V., 1996. On the mixture model for multiphase flow, Finland: VTT Publications 288, ISBN 951-38-4946-5.Search in Google Scholar
12. Ranz, W.E., Marshall, W.R., March 1952. Vaporation from drops, Part I. Chemical Engineering Progress 48(3), 141–146.Search in Google Scholar
13. Schiller, L., Naumann, Z., 1935. Z. Ver. Deutsch. Ing. 77. 318.Search in Google Scholar
14. Schmidt, J., Egan, S., 2009. Case studies of sizing pressure relief valves for two-phase flow. Chemical Engineering and Technology 32(2), February, 2009, 263–272.Search in Google Scholar
15. Song, A., Cui, L., Cao, M., Cao, W., Park, Y., Dempster, W., 2014. A CFD analysis of the dynamics of a direct-operated safety relief valve mounted on a pressure vessel. Energy Conversion and Management 81, 407–419.Search in Google Scholar
©2015 by De Gruyter
Articles in the same Issue
- Frontmatter
- Editorial
- Special Issue Published in the Occasion of the 13th International Conference on Multiphase Flows in Industrial Plants (13th MFIP) held in Sestri Levente (Italy) from the 17th to the 19th of September 2014
- Special Issue Articles
- Behaviour and Stability of the Two-Fluid Model for Fine-Scale Simulations of Bubbly Flow in Nuclear Reactors
- A Model on the Stability of a Pipe in an Aerated Silo
- Enhancement of MSF Using Microbubbles
- Single Air Bubble Breakup Experiments in Stirred Water Tank
- Frictional Pressure Drop during Two-Phase Flow of Pure Fluids and Mixtures in Small Diameter Channels
- A Practical Approach to Operational Hydrodynamic Slug Analysis in Pipelines
- The Thermosiphon Cooling System of the ATLAS Experiment at the CERN Large Hadron Collider
- Energy Intensity Reduction of Ca-Looping CO2 Capture by Applying Mixing Loop Seals and Cyclonic Systems
- A CFD Study on Two-Phase Frozen Flow of Air/Water Through a Safety Relief Valve
- CFD Study of the Hydrodynamics of Slug Flow Systems: Interaction between Consecutive Taylor Bubbles
- CFD Simulations Devoted to the Study of Fitting Effects on the Phase Distribution in Parallel Vertical Channels
Articles in the same Issue
- Frontmatter
- Editorial
- Special Issue Published in the Occasion of the 13th International Conference on Multiphase Flows in Industrial Plants (13th MFIP) held in Sestri Levente (Italy) from the 17th to the 19th of September 2014
- Special Issue Articles
- Behaviour and Stability of the Two-Fluid Model for Fine-Scale Simulations of Bubbly Flow in Nuclear Reactors
- A Model on the Stability of a Pipe in an Aerated Silo
- Enhancement of MSF Using Microbubbles
- Single Air Bubble Breakup Experiments in Stirred Water Tank
- Frictional Pressure Drop during Two-Phase Flow of Pure Fluids and Mixtures in Small Diameter Channels
- A Practical Approach to Operational Hydrodynamic Slug Analysis in Pipelines
- The Thermosiphon Cooling System of the ATLAS Experiment at the CERN Large Hadron Collider
- Energy Intensity Reduction of Ca-Looping CO2 Capture by Applying Mixing Loop Seals and Cyclonic Systems
- A CFD Study on Two-Phase Frozen Flow of Air/Water Through a Safety Relief Valve
- CFD Study of the Hydrodynamics of Slug Flow Systems: Interaction between Consecutive Taylor Bubbles
- CFD Simulations Devoted to the Study of Fitting Effects on the Phase Distribution in Parallel Vertical Channels
