D0 Silicon Upgrade: Calc. to Determine Need for a N2 Phase Separator

A nitrogen phase separator is recommended on the liquid supply line at the helium refrigerator plant. This engineering note documents the calculations done to reach that conclusion. The steady state liquid nitrogen consumption rate for the refrigerator, VLPC and solenoid systems is about 30 gal/hr. The estimated heat leak for the piping run to the refrigerator location is 50 watts. The calculated quality at the refrigerator was 0.032. Given this quality, a two phase flow model based on Lockhart-Martinelli and also incorporating Baker diagram nomenclature was run on TK solver. The result of this program was that without the use of a phase separator we could expect a slug flow pattern with a volume fraction of gas of 65%. Based on this, I recommend that we use a phase separator to siphon off the gas before the nitrogen is sent to a standard saver type subcooler. Including the phase separator will help ensure proper operation of the subcooler. The subcooler will help us attempt to deliver single phase liquid to the nitrogen control valves.