Not computer related, but cooling related

Hey guys, i know this isn't computer related but it sure is cooling related and you're the only guys I know that might now the answer. I work for a sculptor/artist and he is interested in making some freezing related sculptures etc. but they would need to be frosted over at all time. For example he would want to cool a metal table (best metal for this?) and have the whole top of it frost over and perhaps if you put something on top like a small sculpture or a bronze piece so it would frost over as well. I was looking at the OCforums freeze gallery and I see alot of surface area that can be frozen using a phase change unit. So heres the actual question. Whats the best way to accomplish this project, what size could the area be (max), what type of cooler, what metal would be best for the freeze transfer and could it also make bronze frost (considering the bronze consists of 95% copper, 2% silica, etc.) thanks

Hey guys, I was trying to see what we have laying around the warehouse that we could use and this is what I found. Perhaps I could scavange parts from this? Its about 20 years old but was only used for about half a year, looks pretty dirty but should work fine.

You could make several evaporators and place them strategically throughout the underside of the table. I don't know if you'll be able to get it cold enough with just that unit though. What are the specs on the compressor?

It looks like a decent sized condensing unit.

One big coil in coil under a table would be an option as well.. and as far as materal to use it would be the same suspects. silver, copper bla bla bla or whatever is reasonable for the project..

and you do reilize that phase as it's used for this hobby is increadbly small right? your comments about IF it can do it and maximum area are a matter of sizeing the unit correctly thats about it.
How to calculate it? heck your dealing with open air who knows how much surfase area and mass

Yeah thanks, the surface area I'll have to most likely find out by trial and error. Oh and i got some specs off the unit.

R22
29,000BTU
3493 Watts
16.3Amps

Yea.. thats big
~2 1/14- 2 1/2 HP

thats quite a bit bigger then anything needed for computer related projects (well other then some auto-cascade experiments that are rather new to the hobby)

If there is a decent budget for the project get the R22 recovered out of the unit by a HAVC shop.

you could attach the new evap right up there at last bend going to the current evap. and just remove the current evap/fan/fan shroud off the unit and encolose it if you like
Just an idea

It just occured to me to mention that that compressor could probilby use an oil change

ya notice the oil cooling circuit (At least that is what it looks like)

Best thing to do is select your metal toped table and insulate the top and bottom with the blue cyanofoam board and cut holes into it where you will have the sculpture the unit its self can use a thorough cleaning and as green had mentioned an oil change. For a system like that a TXV will be essential and a suction line accumulator. you'll want a 1/4th liquid line and depending on length of the run either 3/8 suction if it is a short run or 1/2 if it is a long run

TXV Size 2.5Tons, Liquid line receiver 2 Pounds capacity, Suction line accumulator = 1 to 2 Pounds,

I don't see the metering device (no cap tube out in the open) there might be a TXV and reciver under the evap's shroud

And I don't see the oil cooling circuit (or what your seeing as one) but you would know what one looks like Xeon
*edit-(Is it the extra plumbing through the condensor??)

Thanks for all the help guys, Xeon... you totally lost me... I always wanted to build a phase change unit for a PC but never got around to it so this opportunity might be a good time to learn. If you could link to where I could read about TXV and the suction lines etc. I do understand how an air conditioner works, and technically shouldnt the current evap start frosting over if theres no fan/shroud, etc.? If you could educate me a bit more guys it'd be greatly appreciated.

The lack of enough air getting pushed through the current evap while its running will make it freeze over.

TXV (thermal expantion valve) is a type of refigerant metering deivce (most air conditioners I've seen use the capalarty tube method). it uses a reciver (basicly a small tank that lets the liquid refigerant settle down at the bottom) and injects the refigerant based on the temp. of the suction line leaving the evap (there is a bulb of refigerant that controlls the valve)

I would give you a link If I knew were one was explained all that well

I wouldn't use compressor cooling, the noise would be a real detriment imo. LN₂ is noiseless and will do a much better job of freezing a larger surface area. There are of course several challenges with his conception. The safety of anyone viewing the 'art' is important. I don't know what scale your thinking about but it could be easy for someone (especially kids) to be burned from the extremely low temperatures. Also the flow of liquid inside the piece, for instance a flat horizontal surface would be harder to freeze because the liquid flowing underneath it would probably not be touching it. You could either pump the liquid (more challenging & would allow for a more varied use of frozen areas), or let it sit static (no pumping system to worry about but less flexible in the use of frozen areas in the piece).

Yes it will freeze bronze in addition to most other metals you might be using.

This has to be semi-permanent though. I would have to keep adding LN2 wouldn't I? The idea is just to have it sitting there without any maintenance.

http://hvacwebtech.com/marksM2.htm < Link to details of TXVs.

Green yes, it is the extra piping that you see, they could be doing some thing ells but at that capacity I think it would be safe to say it is indeed a cooler for the oil.


Phase system is the only approach, LN2 is not an option, try thinking about suggestions and feasibility, That recommendation is dangerous in that sort of setting, it could even deplete the oxygen levels in a room fairy fast if the vent system isn't up to par for that type of usage of the space.

The over all surface of the table MUST be fully insulated along with the bottom and sides, then the holes cut for the base of the artwork this will reduce loade.

at 2.5 Tons nominal cappacity and 2Tons Viable Opperating that will most likely have close to a pound of R-22 in it or so, so you'll definately have to have it emptied by a certified tech, then do the work and have it commissioned to be legal and safe.

Now what I'd do, is get a table that has a wooden deck, get a router and mill out the best patern for the piping on the wooden deck and then put in 3/8 for the evap with neropren foam under the pipe, so that 3 to 5mm of the pipe is above the cut in grooves, then bolt on some aluminium sheeting over the deck, then secure blue cyanofoam on top and bottom along with the sides with the two ends of the pipe sticking out 2 feet.

With the plant I would clean it up and get it emptied and pressure tested, Now if it was using a capillery tube, I would remove that, add a receiver that had a 2pound capacity (Basicly it should hold a 120% of the total systems charge) then after the reciver a filter dryer, and sight glass; For the Vacuum side I would add a 1/2" SAE Flare connecter this will be brazed on and secured to the frame of the Condencere plant and after the sight glass a 3/8" SAE flare connecter should be brazed on then secured to the frame of the condencer plant.

Now, with the 2feet of 3/8 pipe sticking out; Place the condencing plant (The A/C with out the evap) in a conveniant spot under or around the table where it will live and opperate; Start messuring how the tubing must be routed, make any needed bends, now cut off any access piping, now Braze on a 3/8 to 1/2 Inch converters and add 5" of 1/2 tubing, this is how the TXV and suction line will be connected; Put on a 1/2" SAE Flare Nut and then flare it (You'll have to probably get a proffesional to do the flaring as it is tricky) and on the other one add 3" of 1/2" pipe and braze on a 1/2" SAE flare and secure to the table.

Now at this point the the table and condencing plant will be totaly seperate; The condencing plant will have two connections, 1: 3/8th" male SAE Flare, and 1: 1/2" male SAE Flare. The Table will have 1: 1/2" Female SAE Flare and 1; 1/2" male SAE Flare.

The TXV will go onto the 1/2" Female flare and will connect to the 3/8th" Flare on the Condencing plant; And between the table and the condencing plant you will bolt on a 1/2" diameter peice of pipe for the suction.

This will make the unit portable to a degree, as in you'll be able to break it up and move it, how ever you'll have to get a tech to recover the refrigerant and vacuum it each time to charge it once re-assembled.

I will add in a MS paint later.

http://www.refrigerationbasics.com/1024x768/rb1.htm < FYI this will help you understand the system I have out lined.

Thanks for all the help guys, i'll give it a shot.

XeonStrikeForce said:

Phase system is the only approach, LN2 is not an option, try thinking about suggestions and feasibility, That recommendation is dangerous in that sort of setting, it could even deplete the oxygen levels in a room fairy fast if the vent system isn't up to par for that type of usage of the space.

Click to expand...

You must have missed my comment on safety, not to mention the fact that LN₂ effects are commonly used in theatre in much higher volumes than I was suggesting. I was simply trying to offer the best approach to freezing metal, not evaluate it's dangers. I would expect anyone trying something like this to be fully aware of the dynamics and how to handle them. You can easily find hundreds of pages of things online to do (play) with LN₂ that are far more dangerous, so please don't tell me I'm giving someone a bad suggestion.

The reason I made that recommendation is based on the thought of walking into a gallery or similar and the only thing I can hear is a compressor running. Not my idea of a nice experience particularly when I envision ice as a silent experience, except when overclocking Maybe the best idea is pelt cooling. No noise, not as cold as LN₂ or phase but still hopefully cold enough to get the desired effect.

In theatre (at least in closed box ones) They use a special fluid to make fog thats it not LN2 based, In open box or high mass volume air flow studios they use crushed dry ice and water. Secondly it would not be practical due to the fact it would need near constant refilling.

The phase system can be put into a separate room or sound isolated. The pelt Idea is a good but powering will be complex due to the high currents, and then cooling, it will require either a massive fan system or a water cooling system, IE there is noise so might as well go with the most functional and the least power consuming = Phase. I thought this through very care fully be for replying to the thread. When doing stuff like this there are alot of codes, the PELT Idea is good how ever getting it certified will be a night mare due to the electrical (They do not at all make it easy <_< )

The system he has is simplistic on the electrical circuit and by geting it commissioned by an HVAC tech he can use it with out issues.

Just a couple of examples

http://www.interesting-products.com/faq.html
http://www.plsn.com/Current-Issue/Feature/FTR1-June06
http://www.imageengineering.com/Library/Pages/FAQ_QnA.htm

I'm not sure how you propose to put the phase system into another room, that would be an interesting challenge. But from what trigger has said maybe he doesn't mind the noise and he already has something to work with. The other advantage with Nitrogen is it could cool whatever surface area you want, large to small. Phase would be very limited.

well here in BC we don't use it in any thing but BIG productions, for the smaller scale stuff I see it highely unlikely of being allowed & notice how they pump air into the area and lots of safety mechanisms? Again phase is the only realistic option for him and his application, as for limit it comes down to his skill.

Make the sculpture hollow and use it as the evap of the loop, it will get nice and frosty.

You can use a copper pipe as the evap and wrap it around or have it touch the sculpture in pultiple places.

Dont know if a cooled table would keep the top of the sculpture frosty if its pretty large.

XeonStrikeForce said:

as for limit it comes down to his skill.

Click to expand...

so true, that and money, this venture is not cheap, how deep are his pockets...