Self-Pressurising Storage Tank Under Isochoric Constant Volume Conditions

1 Self-Pressurising Storage Tank Under Isochoric (Constant Volume) Conditions 

If a tank of cryogenic liquid is allowed to pressurise, with zero boil-off, flien the evaporation is progressively suppressed as the ullage pressure rises, and a surface layer is created with a rising saturation temperature in equilibrium with the increasing ullage pressure. 

The superheated wall boundary flow feeds into this surface layer without evaporating, and a saturated upper layer builds up above a lower layer at the initial filling temperature. As the pressure rises, the density difference between the two layers remains small, so that the auto-stratification is very stable wifli no sudden spontaneous mixing and therefore no rollover (see Chap. 7). 

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