A CFD study on two-phase frozen flow of air/water through a safety relief valve

Moftah S. Alshaikh, William Dempster

Research output: Contribution to conferencePaper

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.

Conference

Conference13th International Conference on Multiphase Flow in Industrial Plants, MFIP13
CountryItaly
CitySestri Levante
Period16/09/1419/09/14

Fingerprint

Safety valves
Pressure relief valves
Two-phase Flow
Computational fluid dynamics
Safety
Water
Air
Liquids
Liquid
Refrigeration
Two-fluid Model
Gases
Mixture Model
Droplet
Slip
Non-equilibrium
Fluids
Industry
Tend
Predict

Keywords

  • two-phase flow
  • CFD analysis
  • multi-dimensional modelling
  • refrigeration engineering

Cite this

Alshaikh, M. S., & Dempster, W. (2014). A CFD study on two-phase frozen flow of air/water through a safety relief valve. Paper presented at 13th International Conference on Multiphase Flow in Industrial Plants, MFIP13, Sestri Levante, Italy.
Alshaikh, Moftah S. ; Dempster, William. / A CFD study on two-phase frozen flow of air/water through a safety relief valve. Paper presented at 13th International Conference on Multiphase Flow in Industrial Plants, MFIP13, Sestri Levante, Italy.10 p.
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Alshaikh, MS & Dempster, W 2014, 'A CFD study on two-phase frozen flow of air/water through a safety relief valve' Paper presented at 13th International Conference on Multiphase Flow in Industrial Plants, MFIP13, Sestri Levante, Italy, 16/09/14 - 19/09/14, .

A CFD study on two-phase frozen flow of air/water through a safety relief valve. / Alshaikh, Moftah S.; Dempster, William.

2014. Paper presented at 13th International Conference on Multiphase Flow in Industrial Plants, MFIP13, Sestri Levante, Italy.

Research output: Contribution to conferencePaper

TY - CONF

T1 - A CFD study on two-phase frozen flow of air/water through a safety relief valve

AU - Alshaikh, Moftah S.

AU - Dempster, William

PY - 2014/9/18

Y1 - 2014/9/18

N2 - 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.

AB - 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.

KW - two-phase flow

KW - CFD analysis

KW - multi-dimensional modelling

KW - refrigeration engineering

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M3 - Paper

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Alshaikh MS, Dempster W. A CFD study on two-phase frozen flow of air/water through a safety relief valve. 2014. Paper presented at 13th International Conference on Multiphase Flow in Industrial Plants, MFIP13, Sestri Levante, Italy.