Chiller/ac unit

[jamaljaco]

Originally posted by kayl
hey all with chillers
how long you have to run the chiller to get good temps
before you turn the pc.
iv seen lots of people running over night to get -20.
what are some expected temps to get for running a chiller running say 10mins before turning on, (starting off with room temp h20)

In about 20 minutes I can boot my xp 2500+ @ 2500 mhz with -17c coolant temps after about 20 more minutes I can get her up to max clocks @ -25c coolant temps.

[Gary Lloyd]

You wouldn't believe what a TXV would do for your chiller, Jamal. Like night and day.

[Conflict]

Originally posted by kayl
hey all with chillers
how long you have to run the chiller to get good temps
before you turn the pc.
iv seen lots of people running over night to get -20.
what are some expected temps to get for running a chiller running say 10mins before turning on, (starting off with room temp h20)

My chiller when running was chilling the liquid down to close to -20 within only an hour of use

[jamaljaco]

Originally posted by Gary Lloyd
You wouldn't believe what a TXV would do for your chiller, Jamal. Like night and day.

ok, I'll bite , describe "night and day".

[Gary Lloyd]

Well below -40C in a fraction of that time.

[jamaljaco]

Originally posted by Gary Lloyd
Well below -40C in a fraction of that time.

Geek Goddess and I have been busy building a shop in our basement so we will have a place to work on such things. I'm also looking to score another ac for her chiller and another for me so I don't have any downtime.
I will have two complete systems, one to use and play on while the other is being modded in the shop.

[jamaljaco]

Also, why TXV as opposed to cap tube?

[Gary Lloyd]

A cap tube meters a fixed flow of refrigerant, removing a fixed amount of heat. A TXV opens up and provides a heavy flow, removing a lot of heat when the heat load is high (during pulldown), then tapers off as the heat load drops.

Its like the transmission on a car. The cap tube is like having one gear. The TXV is like having an automatic transmission.

Your chiller is currently in low gear. This gives you fast pulldown, but temps are not as low as they could be.

We can make the cap tube more restrictive. This would be like high gear. Slower getting there, but eventually lower temps.

The TXV gives you both faster pulldown and lower temps.

[chilly1]

A TXV will respond to load and close as it gets colder maintaining superheat. This will allow it to get a lot colder than with a cap tube. Have you heard of the capacity / temperature trade off of a cap tube? Well with a cap tube you can have it colder but you lose capacity or you can have capacity and you lose temperature, With a TXV it will maintain a set superheat and a predesigned capacity through a sensing element(Bulb) connected to the discharge line of the evaporator.

[Russell_hq]

Why dont you install 2 cap tubes, with the second controlled by a valve. Open the valve on start-up to give you greater capacity and quicker cool down times, then close it off to get the lower temps. This way you can change the flowrate without using a TXV, something to think about.

[DaBit]

wouldn;t that be just as expensive as using a TEV?

[zakelwe]

Well after 20 odd pages of people bending tube and being far more adventurous than I could ever be, my own very easy to build and to be honest very heath robinson affair is taking form. Stop laughing at the back Gary, chilly1 and dabit.

You have to walk the walk not talk the talk ...... OK, I am staggering

Now the disclaimers

1) My coolant sprung a leak tonight and covered the kitchen floor

2) I'm measuring all temps with a thermometer that is, although called Oregon Scientific, only as scientific as what NASA uses to measure the cooking food stuff in their cafe for lunchtime .

Right, here it is



spot purpling mess under chair ..oops
spot 1 metre of plumbers insolating tube on 3 metres or tube




The spare block is looking frosty so me thinks room temp has been broken ..yippee

But not by much if the turkey thermometer is to be believed !




-20C into the block -2C out .. maybe I should buy a Fluke ?

Stick it on my 80w Peltier



that's a bit better, have no idea what proper temps should be at this stage but obviously going in the right direction .



Double cascade will never beat that



Regards

Andy

[Gary Lloyd]

Red Green, eat your heart out.

Thinking most will not get the reference here. Red Green is the star of one of my all time favorite comedy shows, "The Red Green Show". What he can do with duct tape is a wonder to behold. His motto is, "If you can't be handsome, at least be handy".

[afireinside]

Duct tape is amazing :O

[kommando]

Originally posted by afireinside
Duct tape is amazing :O

Yer its great it has many abilities including taping people up to poles and leaving them there.

[jamaljaco]

GeekGoddess turned me on to red green! Its one of her faves.

[jamaljaco]

Zakelwe , what you using for coolant? I'm also thinking a few bottles of vodka or higher prof alcohol might work better than the beer.

[jamaljaco]

Also thanks for the TXV explanations guys it helps.
However I do forsee some potential problems with reaching -40C. Pump and tubing concerns. I can't test gear for -40C till I get there ,lol.

[jamaljaco]

Cleaning out the paint shed at work the other day, I scored 10 gallons of straight ethyl alcohol denatured with Isopropyl, a lot less toxic than methyl alcohol, I also scored 5 gallons of pure methyl alcohol nasty stuff. Free is a very good price!

[kommando]

Damn i wonder what my idea will hit, hopefully -40 then the pump etc. problems.

[afireinside]

Tygon will be fine at -40C I'd think as long as you dont touch it...

Pump is another problem. -40C would probley crack my Eheim 1250 after a few weeks and slaughter the flow rate. Not to mention I'd need like a 75:25 meth/water mix :banana4:

[Gary Lloyd]

Well after 20 odd pages of people bending tube and being far more adventurous than I could ever be, my own very easy to build and to be honest very heath robinson affair is taking form. Stop laughing at the back Gary, chilly1 and dabit.

Nothing at all wrong with this strategy. There is a special place in my heart for ghetto systems. I love ingenuity.

Just a couple small drawbacks here. The compressor being small, it will take a while to get down to temp, and once the computer is running it will not be able to keep up, which means the temps will gradually rise. In the meantime, bypass the thermostat, and let's see how low it can go.

[aenigma]

In addition to what Gary has said, it looks as though your coolant is sitting in a reservoir and not touching the evaporator pipes.So your primary cooling is the cold air around the plastic container.

Way way back I used a chest freezer and it couldnt hold 5c it worked so poorly.It was alot bigger than yours so I didnt have the option to fill it all the way up(only filled the bottom) but later I ripped the sheet metal off the sides and then just tie straped some copper pipes to the evaporator pipes and hit -20c in no time.By then I wasnt using it but I was starting to get into refrigeration at that point and had to play with it!I think you should check and see if it is water tight and if it is, fill the whole thing with your coolant.

Congratulations on getting it working and good luck.

[zakelwe]

Well I have a hangover this morning

Thanks for the tips guys, yes it's certainly not optimised yet that's for sure. I run 3dmark benching so 1 to 2 hours is all I need out of it, however being in a plastic container not really touching the side meant the time to get down to -20C for the liquid was 24 hours, mainly down to surface cooling of the liquid I guess.


The freezer is not waterproof so it will have to be a container, metal ideally, I will keep my eyes peeled. Sitting under the tub is 15m of copper 10mm tubing so I might atach the plastic pipes to go through that to precool the hot returning liquid before it goes back into the lake. However this is 10mm and so will need another pump in series to keep speed up. I'm not an expert in thermodynamics but I have the logical thought that a lot of cold metal surface area in contact with the liquid will be the reverse effect of the hot copper on the block touching the cpu. I guess my think is right , no???

Nice idea to go by the evap pipes , I'd be a bit concerned I might break one.. I'm a bit hamfisted and maybe couldn't get duct tape on fast enough before all the gas escaped

Gary, how do I bypass the thermastat ? Can I have fun and use a hammer, or is it more technical than that ?

Regards

Andy

[Gary Lloyd]

There are two wires going to the thermostat. Put them together.

But unplug first.