Cooling NL11F Single-Stage

Hi everyone, this is my first post here . I'm Brett (aka Brettbeck), you might have seen me lurking around various other forums here and there. I'm from Sheffield, UK and i'm 16 (just left school).

Anyway I wanted to show people here a custom made phase change unit that I recently made. My friend Alan has recently also got into phase change cooling and he bought his parts down to mine so I could show him how to make them .

So a few weeks ago Alan came down to mine and we built this small single-stage. I don't actually know many specs about the unit (because quite a few of the parts have just been randomly put together lol ), although I know it has a Danfoss NL11F compressor, 3 row condenser and an acumulator lol .

Anyway here are some pics;

Getting some parts together



Started brazing the DSH coil on and a few other things here and there



Condenser from the side



Electrics need doing at some point



Vacuumed the unit for about half an hour or so to make sure Alan's vac pump worked ok



General view of the unit. You can also see we soft-soldered the captube on to the acumulator



With case top on



Front end



This unit is still far from finished but we will be working on it again soon. We still need to do the electrics, bolt everything to the base, screw the fan into the condenser, vacuum it out properly, insulate and some other things. We will update the thread as it is progressed .



UPDATE: From 29th May .

We had some problems with the electrics yesterday, so today we went to our local refrigeration supplier and got a new relay for the NL11F. The motor in the compressor now fires up perfectly .

Also we were both told that all new compressors come bone dry with no oil in. So, Alan filled the compressor with some proper POE oil and was then notified that the compressors do infact come pre-charged with oil. So last night at about 12am I went and choped the compressor out and drained the oil overnight.

At the refrigeration supplier today we got a nice 4.5litre jug of oil which I have been told can be used with any compressor and gas and works great, and so it does .

Also went to BOC today and got Alan an oxygen bottle on rent for his brazing kit .


Unit was charged at first with just 2.5bar static, which wasn't enough. We kept adding small shots and then the temperature plumeted to -49°c . We were going to use Alan's new refrigeration scales to tell you guys exactly how many grams the unit took but it needed a new battery so it wasn't possible.






Closer up picture of the units suctionline and evaporator frosting up.



Evap itself .



Running pressures for Dave .



Insulated with red cable sleeving, red heatshrink and enclosure on the lineset.










Something that we were both gobsmacked at was how quiet the compressor actually is ! When we fired it up the only thing we could hear was the fan... we thought the compressor motor wasn't even running at first. Ran quite cool too, after about 30mins running it was just warm.


Alan has a 300W cartridge heater which we will use to load test and tune the unit sometime soon. Stay tuned for more results .

Feel free to ask any questions .

 

That looks like a great little unit. Nice construction too, not sure I'd enjoy having a cylinder of pure oxygen kicking around, but there we are.

Want to see some load-temps now, although I think 300W is plenty tbh.

 

Thanks . We probably won't tune it for 300W, that's just the cartridge heater. The load tester will have a variac conncected to it so that we can adjust the heat output.

I think it will probably be charged for 200W... roughly for the spec of a dual core processor. The unit will probably end up on a Conroe chip so... . Loaded temps will be posted when it's tuned.

About the oxygen cylinder thing... it's ok to have them just as long as you know what you're doing with them. If you store them correctly and use proper equipment (regulators, flashback arrestors etc) you are fine.

I have this in the garage here lol . There is also another small bottle of propane behind that box on the floor. There are about 5 heavy duty chains rount the cylinders so they don't fall... that's one of the worst things that can happen.




And this is the workbench .

 

That's a great setup, love it. Where did you learn to weld? Seems like an unusual hobby for a 16-y-o, I must admit I'm jealous, too much watching scrapheap challenge.

I know the flashback arrestors etc are basically foolproof, but being in an enclosed space with a cylinder of O² would still make me worry a touch.

 

I learnt to braze (or light weld) mainly from experience and from talking to other builders. I also talked to the guys at our local BOC place and another welding shop. They were all really helpfull and told me what I needed to do . I found hands on experience was the best way to learn really.

I work in the garage mainly because I can open the door and there be plenty of ventilation, which is important when working with gases. As long as the cylinders are stored within the criteria on the data sheets for the gases, you shouldn't need to worry .

 

good to see that youve joined here as well as oczf brettbeck!!! guess ill be seeing you here and there then!

 

your only 16!!!! wo you have skills! how much did it cost ya/him to make????
how do you have the money for phase at 16? im soon to turn 17 and i hardly have anymoney!

 

. I thought it would be cool to post some of my builds on more than just 1 forum .

I'm not sure how much it all was together for that build. Most the parts are bought from abroad and imported because they are waaay too expensive here!! We are ripped off for everything in this country!

I've been into phase for a few years now. The only way i've been able to afford all the tools etc is by not upgrading my PC for about 2 years lol . I also look out for deals and make sure I pay the right price for things .

I'm 17 in September and i'm probably going to want a car, so I don't know what will happen to all this phase stuff yet. I will probably end up keeping the tools so I can build again in the future if I manage afford both things lol.

 

lol klkl! yer i have my case mod featured on here oczf and kustompcs!

i like the fact that my parents are buying my car!!!! lol

 

That's some mighty fine work you've got there!

And there's no need to tell me about the financial situation of being 16 it sucks for sure.



On a slightly less related note, have you tried using different refrigerants before? you can get better performance with the same kit by using a different gas. IIRC, R22 might be better. Also, I don't notice an oil separator in there. It's a £5 investment that can save your system from getting clogged with oil.

 

you're so lucky!! My parents might pay for my driving lessons if i'm really lucky, but the car itself! No chance .

Thanks . I see i'm not the only one then with the crappy financial situation LOL .

Yes different refrigerants and gases will give you different temperatures. R22 is probably about the same as R404a. If we had it, we could have used R402a, R507a or R410a for colder temps and probably better load handling capabilities . R410a is really high pressure though.

Oil seperators aren't needed in single-stages. As long as you use good quality oil (like we have done)... it won't freeze until about -70°c or sometimes even colder. With these small systems you tend to find you don't need as much oil in as what you would if you were putting the compressor to its proper use. Most compressors used in phase change work in environments they really aren't supposed to.

Also, you can't get a proper oil seperator for £5 . For that you might be able to buy a small piece of wide copper tube and put some copper wool inside and braze that up, but then you would also need a hand-valve which is at least another £10!

 

lol they are paying for the lessons aswell! and insurance!!! lol i couldnt believe it either!!!

 

I've seen single stage systems get to -62, -65 ish and even with good oil, it can get very viscous at these temperatures.

That's the method I've used; a pipe with copper wool in it is sufficient 99% of the time. And can be made for a fiver.

But yeah, it's not absolutely required, but you've got a nice system there but to have to quit on you because the oil wasn't flowing would be a real pain in the ass!

 

To be fair cars aren't the expensive part - insurance is. You can easily get a good car for a couple of hundred quid, but the insurance will probably be more like 4x that for a newly passed driver.

 

a couple of hundred?????!!!!! what kind of car do you cosider to be 'good'

 

Oxygen's pretty safe, largely because there is so much of it already in the atmosphere. Even the big bottles like that only hold about 3 cubic metres (14 litres at 200 bar) worth of gas at atmospheric pressure, so they won't make enough of a difference to the atmosphere around you even if completely vented that things spontaneously combust.
Hydrogen's pretty nasty (big bangs) while Silane - should you ever come across it - spontaneously combusts when exposed to oxygen. We have them both at work.

 

Loving it, the fact that you built the unit your self is very cool, had myself a small modded vapo about a year ago but it's nothing compared to yours.

Happy OC'ing

-Fr4nk

 

Well alright it's no Ferrari, but you can't hope for a really nice car for your first one. Being realistic, there are plenty of good cars you can buy on a budget.

e.g. Pug 205, Renault Clio, old saloons, allsorts of stuff. Did you never see that Top Gear episode where they bought 3 cars for £100?

Doesn't make much difference if you just plain vent it, until you spray it directly onto something flammable, that's when I don't trust it.

 

:O lol. Insurance is gonna be the killer if it's insured under your name!

I've seen single stages idling at -88°c with no oil problems, also there is a guy in France who builds -100°c cascades without oil seperators . Noone seems to understand why he never has any problems although i'm sure on is imminent.

Remember we have put less oil in than the compressors' data sheet says because the system is so small .

Are you a builder too ? If you make your homemade oil seperator you normally install a hand valve with captube so you can return the oil to the compressor every once in a while. I've yet to see anyone who has made an oil sep with a float in it .

A lot of people building cascades use branded oil separators like the Danfoss OUB-1 which is known to be good.

But yeh, i've never seen anyone use an oil seperator in a single-stage .

Yep you're right, the insurance is easily the most expensive thing. I'm hoping if I can get a job soon I will be able to save up enough to afford a car for a year, then next year work again to keep it.

I'm not too bothered what car I get really, as long as it gets me from A to B that's all i'm bothered about . Even though it's known to be a boy-racer car, if I do get a car it would probably end up being something like a Vaxhall Corsa or something like that. Wouldn't want to spend a fortune on one.

Don't forget that 14 litres at 200bar would be in liquid form. Once the oxygen boils off (at about -188°c), it will expand in volume a huge amount, I don't know the figure exactly but I bet it could be pushing a few thousand times it's volume (from liquid to gas).

I know that dry-ice expands in volume about 1000 times as it boils off to a gas.

I'm using propane as the fuel gas (which works great, within a few hundred degrees of acetalyene). Hydrogen would probably be a bit hotter still but i've been told it's very expensive.

Thanks .

To be honest I think any VapoChill's being run on an overclocked Conroe or better must be modded to keep up. They just aren't tuned for the higher temps!

Oil is one of the worst problems you can have when working with compressed gases. Get the slightest bit of oil on a gas bottle regulator and BOOM! Alan told me a few experiences he had at work when someone cleaned a regulator with a cloth which had oil on it. Falling bottles is a really bad scenario too.

 

Only if you're keeping your cylinders very cold indeed - the critical temperature for Oxygen is -118.6°C, and no matter what the pressure it will be in gaseous form above this temperature. Hence, the Oxygen inside your cylinder will be gas at 200 Bar - so if it's a 14 litre cylinder there will be 200 x 14 litres of gas inside.

Hydrogen gas itself is cheap. Handling it safely is expensive, and welding with it is asking for an explosion. Remember also that a Hydrogen-Oxygen flame is invisible (the blue colour you get from burning methane is due to a Hydrogen-Carbon shift in the combustion process - remove the carbon and you don't get it, while the yellow flame from oxygen poor combustion is incandescent carbon).