Gray's Cascade project

[Gray Mole]

Well I put together the first stage off and on today. Hard to find all the time you need, and my work area is pretty small, so it's slow going.

The enclosure is more ready than the pics show, but the 1st stage is pretty much together. I wanted to put in the suction accumulator, but I'll need to repair the joint on it. It leaked on the pressure test.



I was trying to get pics before the digicam's battery died, so there's not much to look at, but that's the basics of it. The compressor is just the smaller one I have. 1/2HP 404/507 Electrolux. I had some issues getting the larger one brazed, so I'll be changing that one over with the suction accumulator as time goes on. I put a coil in on the suction line to help balance the system. I didn't want the discharge side to be too much larger than the suction, though it still is a fair bit larger.



That's teh first stage's condensor. It's quite big, and the fan is about 150-200mm though I haven't measured it. It blows well, though isn't as loud as I'd expected. It's 240v like the compressor.

Suction line is just barely icing back to the compressor. Ready for finetuning. I wrapped the suction coil I made with a cloth to help insulate it just a little.



Heat exchanger coil. Should do a fine job of cooling/condensing the second stage. Picked it up from Extremecorvette a while ago. Thermal expansion valve is Danfoss 502 TY2 rated -60 to -25. It's been set up to handle up to 700 watts and should be just about right for the second stage to be adequately cooled.



Coldest I got to see was around -47 on the coil. The camera died just after these few pics, and I don't have a spare battery for it so you'll have to wait for more updates. Once the coil is insulated along with the suction line, the temps will be even better, but if the coil can maintain -40 or so with the second stage running I'll be pretty happy.

Pressures were about 6psi Low and 160psi high. I don't like the startup pressures, I have a feeling the TXV is giving grief til it's within it's rated temp. Pulls pretty quick to -20, hesitates for about 20-30 sec's, and then pulls pretty quick to about -40. Takes it's time after that, but no insulation as yet.

I'm using 402a refrigerant for this stage. Danfoss TXV with 00 orifice. Electrolux 1/2HP compressor. I need a couple more things for the second stage completion, and will swap the compressors when I get the bigger Sanyo 3/4HP unit sorted.

Gray

[andL64]

nice work till now

i m actually working on my first autocascade.

the temps are pretty nice for first stage also pressure i think insulated u will hit -50 easy.
which gas are you using for the second stage?

keep it up :wanna see moa:

seEn

[Gray Mole]

LOL should have said...

I'm using R23 for the second. No Ethylene here I'm sticking with the nonflammables for a while

I'm hoping for close to the -100 unloaded 'Money shot' hehehe but realistically I'd liek to see -70 to -80 with a 180w heatload. I don't know if I'm being overly optimistic, but time will tell if it's doable. I'm just kinda miffed that my accumulator gave me grief. Ah well, it's all part of the fun

Gray

[Noxious020189]

So many parts that I have no clue what they do...I know about temps good job I'm happy about getting my system down to a 32C so ummm thats a bit much for me ^ Anyways good job

[runmc]

It looks good so far.

I'm not saying I think it's wrong, and I'll probably get some arguement out of this, but in your situation with that large tube in tube interstage HX, I would have evaporated in the inside tube and condensed in the outside. You have you txv hooked up to the top of the HX with evaporating gas moving down which I think is not good. The evaporating liquid gas mixture should be entering the bottom and moving up as it absorbs the heat.

EDIT for pic and better explanation

[Gray Mole]

To be honest I was thinking about both, and couldn't make up my mind

There's advantages in both ways I suppose, for every one person saying it's better to use the inside, there's another to say the outside tube is better

I don't know. I might change that when it comes apart for the bigger compressor. It'd be nice to know what's the better configuration for sure but we'll see if this is ok with the second stage attached.

It's just nice to finally get some progress on it. Kills you when the parts are sitting there waiting for you

I guess all those years of flaring brake pipes has finally paid off too

All this is the result of a lot of research into 'what works' and it's funny, I think I've 'over-used' it to a certain extent. The desuperheat coil is a little small I think, and I really should have used 3/8" up to the condensor to cushion the startup. The mini-coil to the sightglass I kind of liked, works well enough for accumulation. Once it was all together I stated picking it apart myself though thinking it could be better

Gray

[pythagoras]

Hi Gray,

What are you missing? If I have it I'll send it on.

Regards

John.

[Gray Mole]

Flare nuts.

I can't believe I went to my supplier's and forgot to get the flare nut to fit the oil sep of all things! I'm pretty sure it's 1/4" but don't hold me to that. I'm in that area on tuesday anyway so it's not really a big deal, but I'm sure that's the only thing I don't have.

Well, I don't have my flexi yet either, but I found someone with some and I'm hoping to get a reasonable(ie cheap) deal on those anyway. Will find out tomorrow if that's gonna happen, but will order a couple in if it doesn't work out.

I'm going to stick with captubing on the second stage. I don't know if that's a mistake or not, but I'm going to try it out. After all the issues I've seen people with their cpev's lately I'm gonna steer clear of them for now.

I just need to sort out a evap block now really. I think Chilly's gonna see some of my ££'s for that. I will still have a one-off block done of the design I'm working on and see how it handles but I think his will be the final touch on this. I've got an evap for testing this out at first, but his will go on when it arrives.

Should be all set by next weekend to put the second stage on I hope. Just need to make the time for it

Gray

[pythagoras]

Well I have a chilly1 evap all brazed up with flare connection for suction and captube insitu

Regards

John.

[Gray Mole]

Evil man

I need to order some for some conversions in the future, but that would certainly speed things up Happen to have a couple of 1HP rotaries burning a hole in your pocket as well?

Are you still working on your cascade, John? I figured you'd be putting that chilly head to good use. Will have to PM you (if it get's to you ) and see if I can't talk you out of it

Gray

[pythagoras]

Your not allowed to sell or trade, apart from the in the classified forums, it would be bad form for a mod to do that If you want it its yours.

Regards

John.

[Gray Mole]

A very generous offer, that will be repaid in time

Looks like the project might make better progress than I thought.

Cheers John!


Gray

[runmc]

Okay John!! Now your busted. Your gonna have to turn that evaporator over to me I'm keeping it for evidence.

Your gonna get 30 lashes with a wet noodle for selling outside of the classies. and guess who's gonna give them to ya??

[the_new_guy]

cool man!

runmc why have u painted the hx orange (looks or functionality)?


-mohit

[Gray Mole]

Your gonna have to turn that evaporator over to me I'm keeping it for evidence.

Hehehe

One of the perks of being a mod?

LOL

It's being given as a gift, so no rule-breaking here Just a pile of guilt for me to contend with. The UK is a pretty lean phase community compared to you lucky souls in the US, so it's nice to stick together. I'd love to have John come up here and get in on my project too Would be even better than a Chilly1 evap

After some deliberation, I've decided to take your advice on the HX configuration, and use the central tube for evaporation, and also change the 1st stage inlet to the lower end of the coil, so that the upper end can be the inlet for the 2nd stage condensing. Makes more sense that way. I already went over it at your forum, but if you're trying to maximise gas transfer and minimise liquid heat transfer in the HX itself, then the inner tube is the better one for evaporation as the liquid 'drops out' and collects at the bottom of the tube, maintaining gas transfer. At least in theory lol


Gray

[Cossey]

whats the 2nd stage compressor going to be?

i need to get on and sort out my cascade, im waitng on some stuff from chilly1 (including one of the nice new rev evaps) then once ive got some ethene i can get on and build it.

[Gray Mole]

Actually that's meant to be the second stage compressor.

I've got a 3/4HP unit for the first stage, I just ran into a bit of grief with it, so I put this one on to see if the layout was sound and it's working great. I should ge similar temps and a lot more capacity out of the 3/4 over the 1/2HP one.

I'm looking forward to seeing you results too There's actually quite a few in the UK working on this stuff, it's good to see


Gray

[runmc]

cool man!

runmc why have u painted the hx orange (looks or functionality)?


-mohit

If you paint the brazed joints, it will help prevent rusting. It was just easier for me to paint it all. I used "Rustolem Paint" which help prevent rusting.

[stockhatch]

Great progress so far, and those HX temps are freekin awesome! I wish I could get my IHX down that low An FYI from someone who made the same mistake, dont freeze the IHX unless all tubes are sealed and vacuumed

[Gray Mole]

My lovely wife had some company today for her birthday, and I stayed out of her way as her gift

Hence, I've rebuilt the 1st stage with the larger compressor, and reconfigured the HX pipes as well. I'm vacuuming at the minute, hope to see some results in a bit

Sorry to hear your temps aren't 100% yet Stocky but I'm sure you'll get that sorted out

I think when I look at all the progress other's make on the forum, it's what keeps me motivated

Gray

[Gray Mole]

Maybe I should have left well enough alone

I changed the compressor over to the larger Sanyo, ran the suction through the oil cooler, as recommended for 502 on this compressor. I figured 402 would be a similar issue so that's connected.

I added the suction accumulator, and that seemed to work well enough. I thought it would balance the system a little more effectively.

I couldn't get the thing to run right this time though. I don't know if I had very good contact on the thermocouple, but the best I could get was about -40.

I had it running about 2-3psi on the low, and 160psi on the high to get that temp on the HX, but I couldn't seem to get a liquid head to save my life.

I used the same configuration of the coil to the sightglass as in the pics, and it seemed to be runnig the same kind of temps as before. I'd either be overcharged and high pressures to get liquid in the glass, or just on the edge or a little low on pressure and very little liquid action.

I also blew a start cap today, I don't know about this compressor now, it doesn't seem a very happy starter with any pressure in the system. Even at 50psi it's hard starting. I'll get a new start cap for it, something a little stronger this time and see if that's the problem. It did seem to be a little slow running, might be it's not getting what it needs, but still doesn't explain the lack of liquid.

Ah well, far too tired to keep it up tonight, will post pics of the new layout tomorrow anyway. I'm starting to think I might be looking for a new compressor for the project.

The 1/2HP 'lux worked well, and gave some good results, but I just don't know if it's got the capacity for what I'm trying to get.

Gray

[chilly1]

You do need to flip the condenser .. EVAP inside,... Condenser outside//
Delta T ... warmest to the outside..
And let gravity work for you.. TXV in the bottom will help flood the evap..,, YOu do not want to flood the condenser? Think Liquid trap..

[Gray Mole]

Yup, I'll get the pics up of what I changed, but I put the TXV on the inner tube of the HX, for better or worse and relocated it to the lower inlet. I can't believe I put it at the top before really. Must have been daydreaming

I think I'll be ordering a proper accumulator for the liquid head. I'm sick of trying to tune it 'just right' and that should make it easier. Ah well, just ONE more thing.

I found an online supplier for some start caps for cheap. I'll have to do some creative mounting, but they're just generic caps that would fit anything. 220uF 350v, seems ideal for UK and phase. Don't know if they'll last long, but I'd rather kill a cheap one testing a questionable compressor that a decent one.



That one.

The Supco starters look quite good though. If this will get the compressor going properly I'll look at getting something that's right for it. I realised I was using a 25uF cap. That's a little lean for 1/2HP plus. No wonder it decided to die

Ah well, should get 'em in a day or 2 and can test the compressor again. I hope it's ok, it took some stick to braze up the oil cooler and discharge ports on it. You'll see what I mean when the pics come out. Too short to flare, and too close to the compressor to easily heat it for brazing.

Cheers for confirming that Chilly

Gray

[chilly1]

Is the capacitor a nonpolarized electrolytic?
Does the stat relay drop out the cap after a few miliseconds?

The run capacitor on most 1/2 hp rotary compressors is 25 to 30 uF. SO you will need a Run cap and a start cap.

[wdrzal]

If you paint the brazed joints, it will help prevent rusting. It was just easier for me to paint it all. I used "Rustolem Paint" which help prevent rusting.

I never seen a brazed joint rust unless you are talking copper to steel?