Two-phase discharge flow prediction in safety valves

William Dempster, Wael Elmayyah

Research output: Contribution to conferencePaper

Abstract

Safety Relief Valves (SRV) are necessary elements in the protection of any pressurised system and the prediction of the expected discharge flows is an important consideration for the valve sizing to ensure that rupture pressures do not occur. The high speed flows that occur inside the SRV are complex particularly when a two-phase flow is involved and lead to a less capable protection device which result in larger valves compared to single phase flows. In this paper the ability of a CFD based two phase mixture model to predict the critical flows of air and water through a safety valve is examined. An industrial refrigeration safety relief valve of ¼” inlet bore size has been tested experimentally over a pressure range of 6-15 barg and air mass qualities from 0.1-1 when discharging to near atmospheric conditions for a fully open condition. A two-dimensional mixture model consisting of mixture mass, momentum, and energy equations, combined with a liquid mass equation and the standard k- ε turbulence model for mixture turbulent transport has been used to predict the two phase flows through the valve. The mixture model results have been compared with the Homogenous Equilibrium Model (HEM) commonly used for in valve sizing in non flashing two phase flow conditions. The accuracy of the models over the two phase flow range are quantified and discussed.

Conference

Conference13th International Conference on Pressure Vessel Technology
CountryUnited Kingdom
CityLondon
Period20/05/1223/05/12

Fingerprint

Safety valves
Two-phase Flow
Pressure relief valves
Two phase flow
Safety
Mixture Model
Prediction
Industrial refrigeration
Predict
Equilibrium Model
Rupture
Turbulence Model
Range of data
Air
High Speed
Turbulence models
Momentum
Liquid
Computational fluid dynamics
Water

Keywords

  • safety relief valves
  • two phase discharge
  • prediction
  • CFD

Cite this

Dempster, W., & Elmayyah, W. (2012). Two-phase discharge flow prediction in safety valves. Paper presented at 13th International Conference on Pressure Vessel Technology, London, United Kingdom.
Dempster, William ; Elmayyah, Wael. / Two-phase discharge flow prediction in safety valves. Paper presented at 13th International Conference on Pressure Vessel Technology, London, United Kingdom.8 p.
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Dempster, W & Elmayyah, W 2012, 'Two-phase discharge flow prediction in safety valves' Paper presented at 13th International Conference on Pressure Vessel Technology, London, United Kingdom, 20/05/12 - 23/05/12, .

Two-phase discharge flow prediction in safety valves. / Dempster, William; Elmayyah, Wael.

2012. Paper presented at 13th International Conference on Pressure Vessel Technology, London, United Kingdom.

Research output: Contribution to conferencePaper

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T1 - Two-phase discharge flow prediction in safety valves

AU - Dempster, William

AU - Elmayyah, Wael

PY - 2012/5/20

Y1 - 2012/5/20

N2 - Safety Relief Valves (SRV) are necessary elements in the protection of any pressurised system and the prediction of the expected discharge flows is an important consideration for the valve sizing to ensure that rupture pressures do not occur. The high speed flows that occur inside the SRV are complex particularly when a two-phase flow is involved and lead to a less capable protection device which result in larger valves compared to single phase flows. In this paper the ability of a CFD based two phase mixture model to predict the critical flows of air and water through a safety valve is examined. An industrial refrigeration safety relief valve of ¼” inlet bore size has been tested experimentally over a pressure range of 6-15 barg and air mass qualities from 0.1-1 when discharging to near atmospheric conditions for a fully open condition. A two-dimensional mixture model consisting of mixture mass, momentum, and energy equations, combined with a liquid mass equation and the standard k- ε turbulence model for mixture turbulent transport has been used to predict the two phase flows through the valve. The mixture model results have been compared with the Homogenous Equilibrium Model (HEM) commonly used for in valve sizing in non flashing two phase flow conditions. The accuracy of the models over the two phase flow range are quantified and discussed.

AB - Safety Relief Valves (SRV) are necessary elements in the protection of any pressurised system and the prediction of the expected discharge flows is an important consideration for the valve sizing to ensure that rupture pressures do not occur. The high speed flows that occur inside the SRV are complex particularly when a two-phase flow is involved and lead to a less capable protection device which result in larger valves compared to single phase flows. In this paper the ability of a CFD based two phase mixture model to predict the critical flows of air and water through a safety valve is examined. An industrial refrigeration safety relief valve of ¼” inlet bore size has been tested experimentally over a pressure range of 6-15 barg and air mass qualities from 0.1-1 when discharging to near atmospheric conditions for a fully open condition. A two-dimensional mixture model consisting of mixture mass, momentum, and energy equations, combined with a liquid mass equation and the standard k- ε turbulence model for mixture turbulent transport has been used to predict the two phase flows through the valve. The mixture model results have been compared with the Homogenous Equilibrium Model (HEM) commonly used for in valve sizing in non flashing two phase flow conditions. The accuracy of the models over the two phase flow range are quantified and discussed.

KW - safety relief valves

KW - two phase discharge

KW - prediction

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Dempster W, Elmayyah W. Two-phase discharge flow prediction in safety valves. 2012. Paper presented at 13th International Conference on Pressure Vessel Technology, London, United Kingdom.