G'day,
I'm trying to source a new chiller and am having a dickens of a time finding something suitable.
I need 80KW at -2°C water outlet temp to work at all / minimum acceptable production levels, but 120KW at -2°C water temp to work correctly / normal production levels.
I currently have a fairly heavily modified chiller which uses 3 x independant refrigeration systems using tube-in-tank evaporators in a ~2000L glycol tank @ 25% glycol to chill a 50,000L plain water tank via secondary heat exchangers. This means I can lose 1 of 3 systems and production can continue while repairs are carried out. Unfortunately we're at a point where our modified chiller is falling apart at the seams because it is damn near 30 years old.
No one seems to offer tube-in-tank any more, and BPHE is a no-go because they split too easily if you get a freeze condition.
The next best thing looks to be shell-and-tube, but I'm beggered if I can work out how to have multiple independant refrigeration systems using a single shell-and-tube evaporator. Any manufacturer I have approached has offered this solution but I can't get a straight answer about whether their unit uses 3 x compressors in stages to feed common lines, or if its 3 x independant systems. I want refrigerant loss on one system to not affect the others.
Q. Can you have multiple independant refrigeration systems using a single shell-and-tube evaporator?
A. Appears to be yes, but I cant find any visual examples (pictures, diagrams, video, anything except text) of one providing 3 x refrigeration circuits in a single vessel.
I am assuming(!!) that a flooded evaporator will have the water in the tubes and refrigerant in the shell.... How do you separate the refrigeration systems? Are there internal plates that provide multiple chambers within the shell?
Seen lots of shell and tube heat exchangers, but its always been 1:1 refrigeration:process so struggling to grasp the concept a 3:1 design.
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