kristos

I looked this up earlier but I forgot about it but now, reading one of the threads here the question rises again.

I've been looking around to find out what the difference is between phase change and cascade phase change but all I'm getting is cascade watercooling (and here I have the same question, what's the difference between normal watercooling and cascade watercooling?) and regular phase change.

So what's the deal with this "cascade"? what's so special/different about it?

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jmke

cas·cade ( P ) Pronunciation Key (k-skd)
n.
** A succession of stages, processes, operations, or units.

so 2 phase change to increase the cooling power

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TeuS

a cascade consists out of a high stage and a low stage, both are phase changed cooling. the high stage chills the low stage (let's say the high stage is -40° ), and the low stage chills the hardware at e.g. -100°C

it's comparable to stacking 2 TEC's on top of each other

jmke

but stacking 2 TEC's on top of each other won't increase the cooling efficiently, while the "stacked" phase-change does

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TeuS

it does increase cooling efficiency, but most people don't understand how TEC stacking should be done correctly

you need to use a 72W TEC with a 172W TEC on top of it

kristos

now this is usefull info

although I don't get how you would "stack" phase change units

and what does this stacking mean in terms of watercooling?
does it mean two pumps in the circuit or am I getting this concept of stacking all wrong?

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TeuS

regular phase-change


with a cascade, you have two (or more) phase-change units. let's say unit A and B, each with their condenser and evaporator

Evaporator A chills the CPU. the condensor of A (that rejects the heat absorbed by the evaporator) gets chilled by the evaporator of B then

TeuS

stacking watercooling is impossible.

but you can use several pumps, yes. placing them in parallel doubles the flow, placing them in serial doubles the pressure. I've seen a guy line up three pumps, and one of them got shredded by the excessive pressure

pressure is more important then flow!

FreeStyler

You can stack watercooling, but for CPU cooling it's not going to help, quite the opposite actually. Look at a nuclear reactor, these are cooled by 3 loops. 2 closed and one open.

And pressure being more important then flow all depends on the cooling loop. If you have a low resistance loop, pressure won't even be much of an issue. In a high resistance loop high pressure will increase flow.
In the end it's all about the flow. Pressure just helps you get more of it.

ALL cooling solutions rely on dissapating the heat of the object to the surrounding air.
This can happen with or without extra help. A TEC and phase change use extra energy (that should also be removed) to create a below ambient cooling.
Cascading a TEC or PS with a watercooling is a very effective way to work. The temperature of the water doesn't matter as much as in a regular system because you have an active heatpump in the system.

But in the end, it's all about aircooling.

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TeuS

Amen!