There is a vacuum vessel at very high vacuum condition and inside the wall of vessel, there is a cooling pipe. Water flows in pipe at about 385 K temperature and 8 bar pressure. Due to some accidental condition if pipe raptures, then water ingress in vacuum vessel due to high pressure difference. Due to very low pressure in vacuum vessel (less then 1 pa) flashing evaporation occur. plus wall of vacuum vessel is at very high temperature (around 800 K),so boiling occur simultaneously at water-wall interface. So pressure increase in vacuum vessel with time (vessel is completely close).
I want to calculate:
(1) Time required to reach 1 bar pressure (from initially at 1 Pa) in vacuum vessel for above accident condition.
(2) Total mass ingress in in vacuum vessel in that time.
Hi. I think that your problem is similar to gas explosions, so I would suggest you to look for the modelization of these kind of problems. Specifically, I think that I read something about it by using SPH.
The time will depend on the water ingress mass flow. The process will also depend on the temperature the water will achieve. If you assume complete evaporation of the water and full thermal equilibration with the walls (i.e. T=800 K), then you can use thermodynamics to calculate the mass within the vessel to achieve water vapour at P=1 bar and T=800 K.
If these assuptions do not hold, using the mass flux from the rupture you can attempt a non-equilibrium CFD simulation including wall film and flashing. In the flashing jet droplet size is quite monodisperse, so you can use a Euler-Lagrange droplet model to predict the droplet transport and evaporation.
First of all you have to hypothesize the leakage equivalent diameter and consequently the mass flow rate, that is not constant but decrease increasing the pressure in the vacuum jacket. I think that the leakage inside start from small defect on material or on welding, so I will take a 10% diameter of pipe diameter as equivalent leakage. Normally the leakage start small and increase with time but in this situation you have immediately feeling of leakage.
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