The phase-change help thread

[matttheniceguy]

A water chiller isn't as effective as a direct die unit. There are a lot of losses in all the different themal contacts. The chiller systems you usually see are so big because people typically make them out of air conditioning units. These units are pretty big, and their evaorators are quite large as well. Once you put the evaporatr in a tank big enough for it and a pump, you end up with a very large setup.

-50c isn't very typical for a waterchiller. I would say most units will give cpu temperatures in the -15 to -25 range, although some are better. A direct die sytem with the same compressor and consensor as a waterchiller will probably be at least 10 degrees colder on the cpu. (best guess, not really sure)

 

[sandman001]

Well, I'm making a chiller for jot that fits in the same cheiftec dragon case as his computer, it's very possible to make a compact chiller, and one that performs aswell.

If you plan it out, it's very possible to make one that performs to say -40C or so, and is compact.

 

[redken]

Well, I'm making a chiller for jot that fits in the same cheiftec dragon case as his computer, it's very possible to make a compact chiller, and one that performs aswell.

If you plan it out, it's very possible to make one that performs to say -40C or so, and is compact.

How? I'm very interested.

You see, I'm trying to make an investment that will last me a LONG time. So, a waterchiller would be perfect for me since I can "mold" it easily to my needs now and in the future, just by adding (or subtracting) more waterblocks. Right now I want to cool one CPU and one GPU, but if in the future I want to get two GPU's working together. A waterchiller system would give me the flexibility I need. Just add another GPU block and I'm good to go. And all this, within my current case (which is what I'm looking for).

With a direct-die setup, I would have to make a choice between:

1- One dual evaporator unit for GPU/CPU and live with no option of upgrading to a dual GPU setup in the future, but all inside my current case.

2- One single direct-die setup to the CPU on a separate box underneath my case, keep my watercooling system and pelt the GPU's.

See my dilemma I’m trying to see what my options are in the phase change world , so I can better decide what to do.

My current watercooling system took me about 3 months to plan out and custom build the way I wanted it. This will probably take me the same amount of time.
I love it!


P.S.: What is a cascade? Is it a phase change system using two compressors? And, what is an autocascade? Why does it use only one compressor?

This is a bit confusing. Still have a lot of reading to do.

 

[matttheniceguy]

Cascade: 2 or more phase chage systems running in series. The first stage uses a regular condensor, and regular gases (r290, r22, r134a etc.) The evaporator of this first stage is a heat exchanger that acts as the condensor for the second stage. This makes it possable to use a different gas in the second stage that will only condense at low temperatures (ie -40 achieved by the first stage) but will evaporate at very low temperature. There is a lot of informaton about cascades over at xtremesystems.org.

Autocascade: A cascade system which only uses one compressor. This is a little hard to explain. Imgaine you have r290 and co2 in one system. After going through the condensor the r290 is a liquid and the co2 is still a gas. You run this mix though a tank and seperate the liquid from the gas. The liquid runs to an evaporator/heatexchanger, which acts as a condensor for the co2. The co2 is then liquified and runs to the evap on the cpu, where it evaporates and get's very cold. The evaporated co2 and r290 then go back to the compressor. There are other variations on the design, but that is essentially how it works.

You can make a waterchiller fit in a regular case by making a much more compact evaporator and resevoir. Another advantage of this is that the water will get down to temperature much faster.

Here is an idea, not sure how well it would work though, but a good solution to those who want multiple things cooled. Imagine making a regular direct die evap, but then putting a coil around the suction line right as it leaves the evap. You can then charge the system a little more so there is still some evaporation in this section of the suction line, and run water through the coil. This would allow you to run direct die on the cpu and chilled water on the gpu, with only one system.

 

[sandman001]

How? I'm very interested.

You see, I'm trying to make an investment that will last me a LONG time. So, a waterchiller would be perfect for me since I can "mold" it easily to my needs now and in the future, just by adding (or subtracting) more waterblocks. Right now I want to cool one CPU and one GPU, but if in the future I want to get two GPU's working together. A waterchiller system would give me the flexibility I need. Just add another GPU block and I'm good to go. And all this, within my current case (which is what I'm looking for).

With a direct-die setup, I would have to make a choice between:

1- One dual evaporator unit for GPU/CPU and live with no option of upgrading to a dual GPU setup in the future, but all inside my current case.

2- One single direct-die setup to the CPU on a separate box underneath my case, keep my watercooling system and pelt the GPU's.

See my dilemma I’m trying to see what my options are in the phase change world , so I can better decide what to do.

My current watercooling system took me about 3 months to plan out and custom build the way I wanted it. This will probably take me the same amount of time.
I love it!


P.S.: What is a cascade? Is it a phase change system using two compressors? And, what is an autocascade? Why does it use only one compressor?

This is a bit confusing. Still have a lot of reading to do.

Well, it takes up alot of room inside the case, but it fits. If you pm me your E-mail address I'll send you some pictures of it.

A cascade is one phase-change system's evap cooling another system's condensor. To put it in to easily understandable terms.

An autocascade uses a blend of refridgerants that will condense at different temps/pressures. Basically, the lower pressure gas will condense and is seperated in a phase seperator.

It is then used like the first stage of a cascade, or this is how I understand it anyway. I'm not 100% sure how they work, but I've been reading up on them.

 

[Rekarp]

Im very interested in building a phases change unit over the summer. I understand how it works and everything but what is the size of the components. How big would a 1/2HP compressor be?

 

[sandman001]

Im very interested in building a phases change unit over the summer. I understand how it works and everything but what is the size of the components. How big would a 1/2HP compressor be?

Well, it varies by type, manufacturer, and it's intended application.

 

[redken]

Hi guys!

I'm thinking of going with two phase unit after all. One for my CPU and a dual-evap for my GPU's.
I do have one preoccupation. Since I'll be cooling top GPU's, I'm worried on how to exactly fit the evaporator arms and still be able to close my case. Also, actually hooking them up to the cards.
For example: If I were to use the DFI board, I would be using the bottom PCI slot for my audigy card. If I go over the Audigy card to hook up the evap on the second GPU it would be at a very uncomfortable downward angle and would be pulling on the card quite a bit. Same thing with the first GPU, I would have to go over the second VID card to mount the evap block. Even with the space they have between I don't think it enough because of all the insulation and stuff.
How can I resolve this? Can the tip of the suction arm be finished on an "~" shape and then end in the evap?
Sorry if I'm not explaining myself well, I'll post a rough painting of what I mean tomorrow.

Thanks for all the help, you guys are great!

 

[matttheniceguy]

You can make the suction line coming from the evap from copper pipe like the rest of the system, and put bends in it so everything fits nice. I didn't quite follow what you ment about a two phase unit. It sounds like you ment a single stage unit for the CPU, and then another single stage unit for the two GPU's?

Three evaps in one case... oh boy... your going to be spending a lot of time playing with the die electric grease, seal string and neoprene. Would sure be impressive though. Like I was saying in the other thread, don't bite off more than you can chew. This sort of build sounds like the way to go about it though. You can make the single evap system for the CPU first and once you get that up and running you can tackle the dual evap system.

 

[redken]

You can make the suction line coming from the evap from copper pipe like the rest of the system, and put bends in it so everything fits nice.

Actually I was thinking more in the lines of a flexible hose and at the end of it an "~" shaped copper pipe. At the end of the pipe would go the evap. Something like this:

I hope you guys can get the picture. The blue part would be the flexible hose, the orange would be the copper pipe and the red would be the evap.
I'm not sure if a bent tube like that will affect the PS in any way. The tube would be in that "~" shape and in a downward angle to be able to reach the GPU.

I didn't quite follow what you ment about a two phase unit. It sounds like you ment a single stage unit for the CPU, and then another single stage unit for the two GPU's?

Sorry it was very late last night and I was tired. But you managed to understand me quite well Yes, I'm going to have one PS for the CPU and one Dual-evap PS for the GPU's.
At least that is the best I have come up with…for now.

Three evaps in one case... oh boy... your going to be spending a lot of time playing with the die electric grease, seal string and neoprene.

Yes! Right now I'm doing some research to see how much do I have to cover a card with grease, at the temps of -45 to -50. I have read so far that from dew point to about 0 deg. Using foam and a bit of grease on the socket and around it will do great, but with temps around -50 I might even have to grease up the whole card plus the PCI-E slot, but I don't really know.
Another thing occurred to me while I was looking for info on the grease...dust! Dielectric-grease + Dust + Months of use = Very messy, dusty goo!
The best solution I have read so far is to wrap the card in "saran warp" after I have it covered in grease. On the other hand I read on another post not to use saran wrap because it has static properties and would damage the card.
Two steps forward one step back.

 

[matttheniceguy]

You diagram is exactly what I was talking about. That will work fine. The tricky thing will be making an evaporator thin enough to fit between the cards. I'm thinking you will probably have to have the suction line coming straight out the side of the evap instead of the top like usual.

With the amount of stuff you will have to insulate, I would look at putting the mobo and cards in an airtight container. I would think that would be easier than all the insulation, with the added bonus that if you make the container from plexi or something else clear, you will be able to see the bare copper evap right on the card. I don't know how well this works though, I have seen someone do it will chilled water around their CPU, and it looked and worked great, but phase change might be too cold.

 

[sandman001]

Just make some evap's with 90 degree copper elbos coming out of them for the suction line to attach to.

You have more room there to play with than you think. Insulating this is going to suck though.

 

[Yatta]

Nice great info. I am thinking of this but I didn't know how big to start sounds like 1/4hp is perfect for me.

 

[Rekarp]

hehe picked up a semi broken (door was knocked off) salad crisper yesterday
got a 1/5 HP compressor and a nice condensor on it. Pluged it in and froze the evaporator solid in about an hour. cant wait till summer so i can work on it.

edit/ Found out is uses R22 and its gross to look at. Looks like grease driped all over it

 

[ao`]

I'm thinking of trying to build my own phase change unit. I'm curious, what type of appliances could I find cheap (at a scrapyard, flea market, etc) that would have some of the components that I need (ie. a compressor, condenser, etc)? Where do you guys get your parts and how much do you typically spend?

 

[sandman001]

You can generally get all the parts from E-bay, but as far as a scrapyard, look for fridges, dehumidifiers, A/C's, freezers, anything that gets cold.

 

[Electron Chaser]

Great start to the thread. What I need is some good experience based advice. My Mach II is arriving in a few days. I would like some advice and recommendations on the various pitfalls to avoid when setting this thing up.

 

[XeonStrikeForce]

You discused every thing but the cap tube !, How do I calculate the length of my cap tube for a given heat load or flow rate ?

As for the filter dryer I can answer that. Simply said the Filter dryer does just as it name implies it removes any H2O that may have goten into the system as it was charged and filters out any particles of solder or dirt that was in the system when it was sealed. Sooo if you are a majour tinkerer like my self you will greatly benifit from a vacuume side filter dryer that is much larger then what you need, (becuase I constantly redesign my builds and remake them lol so I need alot a drying to be don!)

 

[XeonStrikeForce]

Secondly I noticed no one mentiond TXVs.

TXV stands for THERMAL STATIC EXPANSION VELVE. A TXV will adjust refridgerant flow to cominsate for heat load, IE As heat load increases the TXV will allow more refridgerant to go into the evap to remove the added heat.

Nice litle link for explaining them with nifty graphics > http://hvacwebtech.com/marksM2.htm

Idealy for water chillers or lager systems you should all ways use a TXV for efficancys sake. How ever a TXV must all ways have liquide condancate(Streight up liquid refridgerant(Known as condancate)) So to do this instead of a capilery tube you have a resivour for the refridgerant to collect in and the TXV will draw on this source to suply the evap.

This is a realy basic not so indepth explination of them as I too am not extensivly familiar with them so I will entrust a HVAC user here to fill out any blind spots if they're willing.

Thanks and hope this helps

 

[Rich2021]

I am planning to build a phase change setup form an old window A\C unit. I was just wondering how much you will see your electric bill go up. My computer is usually only on about 6 hours a day.
Also what would you recommend as the best refrigerant to use in a DD setup.