Morphing Air Conditioner into Autocascade System

[yngndrw]

Very nice work Michael, may I ask how heavy that stack is ?

Looks like it will be fun making sure that it's all insulated internally. (Between the coils.)

[godmod]

Yes Xeon, I completely agree! Michaels skills are so amazing, couldn't hold me back asking

[mytekcontrols]

Oh damn that looks nice and promising! Will you post the whole progress again?

No can do on this project, but I will post highlites from time to time.

Very nice work Michael, may I ask how heavy that stack is ?

14.5 lbs

[[XC] gomeler]

Must find your address and "borrow" that copper to resell Looks like a ginormous stack, best of luck on that -150C goal, hope you crush it.

[yngndrw]

hope you crush it.

If you can't "crush" the temperature, you can atleast crush it with the copper.

Good luck.

[mytekcontrols]

My Base Pan arrived late last week, so I have begun the initial assembly phase.

Below are a few images of some of the main components bolted in place, and the De-Superheater/HXC connected between the compressor discharge and the condenser (I call this my Regenerative HXC, it'll be used to create an oil free Hot Gas source for Defrost).

The HXC Stack is just sitting on the base pan to show its basic area of residence, although in the final process it will be insulated from the pan.

The frame and HXC Stack insulation box utilize what is called T-Slot framing members for the main structural supports. The final assembly will use polycarbonate plastic sheets slid into the T-Slot channels, to create a box around the HXC Stack. And there will be aluminum panels bolted around the outer perimeter to form the unit's enclosure.

[Marvin]

that will be a wonderfull news.

[berkut]

That's a really mean machine you're building there.

I love the heat exchangers, would you be willing to share with us the technique you use to coil them so neatly ? Or is it just the fact you're 50cm around the fore arm and 80 cm biceps ?

When i made mine there was no way i could make them look as good as yours. Coiling them in a flat disc was the only option to make them look neat.

[[XC] gomeler]

Curious, is that small condenser all you are using to dump heat from the system? If I gather correctly, you are using that looped 3/8" copper to separate the oil and that little capillary line coming out of it will be used for your hot-gas defroster. I take it you'll be depending on butane or a similar gas to dump massive amounts of heat through the condenser?

[EvoCarlos]

Michael - when i grow up i want to be just like you
your work is great and i relly enjoy reading this thread
carl..

[tiborrr]

That surely is one hell of a stack Would a e.g. 10-plate HX we normally use in cascades cause too big pressure drop if used instead? Perhaps two 10-plate HXes if one intends to make single-stage autocascade (e.g. R123/R744)?

[Unseen]

Amazing skills
Thanks for being here. I am learning from you.

@Berkut
One good way i used in the past for bending is to fill the pipe with thin sand,
like the one you can find in Greek beachs.

[[XC] gomeler]

That surely is one hell of a stack Would a e.g. 10-plate HX we normally use in cascades cause too big pressure drop if used instead? Perhaps two 10-plate HXes if one intends to make single-stage autocascade (e.g. R123/R744)?

Plate HXs work just fine for autocascades. I plan on using plate HXs since I can't bend copper as neatly

[tiborrr]

So in your opinion two 10-plate HXes will not cause too big pressure drop which could harm the performance?

Would two 6-plate HXes (if one could get a hand on them) be a better solution?

[Moc]

@Berkut
One good way i used in the past for bending is to fill the pipe with thin sand,
like the one you can find in Greek beachs.

not really?

[mytekcontrols]

I love the heat exchangers, would you be willing to share with us the technique you use to coil them so neatly ? Or is it just the fact you're 50cm around the fore arm and 80 cm biceps ?

I do have Popeye arms. Probably from all the years of bending tubing with my bare hands. As for how do I coil the tubing so neatly; it literally is because of many years of experience, and having created quite a few HXC designs. But I'll let you in on a trick. It is very... very important to fix the starting end of the coil wind to the mandrel that you are using to wind it on (fire extinguisher in my case for the outer coil, and large filter dryer for the inner ones). If you let this end slip, then the coil will both grow in diameter as it is wound, and it will most likely kink as well. Also when winding; try to come close to overlapping the previous turn, and let it roll off to the side of it. This will keep the coils tight together.

Curious, is that small condenser all you are using to dump heat from the system? If I gather correctly, you are using that looped 3/8" copper to separate the oil and that little capillary line coming out of it will be used for your hot-gas defroster. I take it you'll be depending on butane or a similar gas to dump massive amounts of heat through the condenser?

Chris, I am gambling that the condenser will be enough for what I am doing. I am also counting on the nature of the refrigerant blend in the autocascade to do a much better job of heat rejection vs. a single stage system (and yes there will be some butane in the mix).

Edit: For extra cooling, I can always add another fan on the opposite side of the compressor if need be.

The looped superheater is not for oil separation, but it is a HXC for creating hot gas from a cold gas source, that being gas taken from one of the downstream phase separation points. And it also serves as a vibration eliminator.

Michael - when i grow up i want to be just like you

Thanks carl. Perhaps when I do grow up, I'll be like me also

That surely is one hell of a stack Would a e.g. 10-plate HX we normally use in cascades cause too big pressure drop if used instead? Perhaps two 10-plate HXes if one intends to make single-stage autocascade (e.g. R123/R744)?

I agree with Chris's response to this question. Actually the plate heat exchangers probably have a little less pressure drop then my stack, and would work even better due to their extended internal surface area.

But as you can see, I didn't have a lot of room to play with in my new design, and using plates would have required much more than what I was willing to allocate. Also believe it or not, my HXC Stack design was very easy to build, and only took me 3 hours from start to finish.

Edit: Even though the pictures show extra space at present; by the time I am done with this build, there won't be hardly any unused areas left (the area above the condenser will be for electrical control, valves and instrumentation, and the space to the right of the expansion tank will be occupied by dual insulated cryo feed-thrus

Amazing skills
Thanks for being here. I am learning from you.

Thanks unseen

[tiborrr]

Thanks for the explanation, mytek, two plate HXes for me it is then!

You are doing fantastic job, keep it up! P.S.: In case your condensor wouldn't suffice, you can always stack another one on top of it.

[plasmatique]

Continuance in the exellence

[mytekcontrols]

Just a little longer, and I should have some more pics to post

Been side-tracked while working on new load controller product.

[mytekcontrols]

Ok here are some images of what I call the Cryo-Feed-Thru. It facilitates getting the final stage Feed and Return out from my insulated HXC box, into some real world connections (Swagelok VCR's). The inside of the stainless tube will be polyurethane foam insulated (same as HXC box), and a special saddle clamp (not shown) will be used to secure it to my Tslot frame.

I can only take credit for the silver solder work on the inside of the cap. A friend of mine at the place I contract to, did the excellent tig welding of the cap to the tube.

I should have more pics of the Feed-Thru being used in the complete assembly within the next week. I'll be sure to post them.

[systemviper]

I love the idea of "Morphing Air Conditioner into Autocascade System ", i have a stand up, rolling airconditioner that i am gonna take apart and see what we got,

thanks so much for all the info you posted, It has given me a wake u call to get rocking, my outside air/antifreeze set up will be warming up in the next 2 moth and i need a new snow maker.

Top notch work and mucho respect

[godmod]

Hey Michael, your new auto cascade is awesome! I have yet a question on your old one regarding the configuration of the high pressure cut out switches (the one for the exp tank/buffer valve and the other one as saftey device #2):

You wrote that you set the "Compressor High Pressure Cut-Out" to 400psi cut out and 300psi cut in. Du you think the compressor will start again? I think the compressors overload protection will "click". Did you think about using a relais to combine it with the buffer valve control switch to let them open both (to make sure the compressor CAN start again)?

next Q: have you put steel/copper wool inside the phase seperator #1?

edit:

I should have more pics of the Feed-Thru being used in the complete assembly within the next week. I'll be sure to post them.

it's next week, so we're waitin' for the pix

[before]

Very impressive.

[s0lid]

Good looking autoc this far once again

BTW could some of you guys add an schemastics for phase sep here (or why not directly to my pm)?

[mytekcontrols]

You wrote that you set the "Compressor High Pressure Cut-Out" to 400psi cut out and 300psi cut in. Du you think the compressor will start again? I think the compressors overload protection will "click". Did you think about using a relais to combine it with the buffer valve control switch to let them open both (to make sure the compressor CAN start again)?

godmod -- Although I see the HPCO as strictly a redundant safety device (The buffer will keep the compressor from ever seeing such a high pressure), I do believe the rotary compressor used on the system in mind could restart at 300 psi. However, in my new system, I have the motor start circuit set-up more like a professional motor-starter. It uses a latching relay activated by a momentary switch to turn the compressor ON, with the OFF switch as well as all safeties breaking the relay coil circuit, thereby unlatching the relay. This way if a fault occurs, the system will not restart after the fault clears, but instead requires the ON button to be pushed once again.

next Q: have you put steel/copper wool inside the phase seperator #1?

Yes on the AC-2 unit I used copper wool, but steel wool would also work.