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lakeside53
03-14-2017, 09:32 PM
OK smart guys.. How much (in theory) dry ice (assume it's at sublimation temp of -78C) will it take to cool 1 gallon of Ethyl alcohol (97%) from -12C (my freezer) to -70C? I'm making a dry ice cooling bath to cool a cylinder sleeve for shrink fit insertion... tomorrow. I'd rather not buy 20lb to find 5lb worked... or 5lb and need more.

Lee Cordochorea
03-14-2017, 10:50 PM
OK smart guys.. How much (in theory) dry ice (assume it;s at sublimation temp of -78C) will it take to cool 1 gallon of Ethyl alcohol (97%) from -12C (my freezer) to -70C? I'm making a dry ice cooling bath to cool a cylinder sleeve for shrink fit insertion... tomorrow. I'd rather not buy 20lb to find 5lb worked... or 5lb and need more.

Mass of alcohol x specific heat of alcohol x temperature change desired < mass of dry ice x heat of sublimation

Therefore mass of alcohol x specific heat of alcohol x temperature change desired / heat of sublimation < mass of dry ice

lakeside53
03-14-2017, 11:22 PM
1 gallon Ethyl alcohol is 2.99 kg.
Specific heat of EA is 0.6cal/gm
Temp change desired = -70- (-12) = 58C
Heat of sublimation is 32.3kJ/mol

The mol part leave me uncertain... CO2 molar mass is 44g/mol.

Now what?

Lee Cordochorea
03-14-2017, 11:36 PM
32.3kJ/mol x 1mol/44g = 32.3kJ/44g = 734J/g

One calorie = 4.184 Joule

lakeside53
03-14-2017, 11:52 PM
I'll give you $1.00 if you tell me the answer ;)


My guess...

2999 * 0.6 = 1799.4 cal per deg C. X 58 = 104365.2 cal. heat to be removed.

104365.2 / (734 x 4.184) = 33.93 grams dry ice.

WRONG... confused...

RichR
03-15-2017, 12:07 AM
I think you misplaced the 4.184
(104365.2 x 4.184) / 734 = 594.91 grams dry ice.

lakeside53
03-15-2017, 12:14 AM
lol.. yes... One beer too many.

Heck... that's only 1.3lb of dry ice! I can afford at least 2X that ;) Petty cheap considering I'll get back most of my Ethyl Alcohol.


I want the 8 inch deep cast iron cylinder sleeve to drop into a cast iron block. I bored the block for a 2 thou interference fit. I hope to heat the Block to 100 - 125C... I get one chance to pop it in or i'll have to resort to driving in cold with a big press. Don't want to do that with a thin wall sleeve.

RichR
03-15-2017, 12:23 AM
Does that mean I get the dollar?:rolleyes:

lakeside53
03-15-2017, 12:28 AM
yep!

Dan_the_Chemist
03-15-2017, 12:49 AM
OK smart guys.. How much (in theory) dry ice (assume it's at sublimation temp of -78C) will it take to cool 1 gallon of Ethyl alcohol (97%) from -12C (my freezer) to -70C? I'm making a dry ice cooling bath to cool a cylinder sleeve for shrink fit insertion... tomorrow. I'd rather not buy 20lb to find 5lb worked... or 5lb and need more.

Ethanol/dry ice baths are good to about -72 C... so you are okay there.

https://en.wikipedia.org/wiki/List_of_cooling_baths

However, the calculation that shows that about 1.3 lbs will be enough has forgotten several things ...

1) cooling the container
2) freezing the water
3) cooling the cylinder sleeve

The container is probably relatively low thermal capacity... but I'd add 10 to 20% just to offset that.

It's only 3% water, but the heat capacity of the phase transition of water to ice is high. To make it more complicated the actual freezing temp of the water in a EtOH/H2O mix depends on the composition of the mix so it's possible that only part of the water will freeze out. Looking that data up looks like a lot of bother, so I'd just assume that all of the water freezes out and use that to calc the heat required to freeze 3% of 1 gallon of water. Oh heck, that seems like a lot of work. Just add another 10% of dry ice to compensate.

You didn't mention the weight and metal of the cylinder sleeve. If it's a thin sleeve that only weighs a couple dozen grams it's not a big thing... but if it's thick and tall and weighs a few pounds then you better add the heat capacity of that.

Don't forget that while you are cooling the sleeve, there will be heat transfer through the container walls. Better add 10% for that.

How soon after you buy it are you going to use it? It's going to be be subliming on the way home. Better add a little for that.

Oh heck, buy a lot ... :)

lakeside53
03-15-2017, 12:58 AM
yep.. all a consideration! I just wanted to get into the zone.. I'll call it 2lb per gallon and never calc it again. This time a 5lb pack will do it.

I'll post pics soon... The bath is thin wall stainless in 3 inches of spray foam. Tiny losses there. Cylinder sleeve - yep - frozen in the freezer so same 58C drop required, but some compensation required. The Ethyl is actually a lab grade mix of 97 parts ethyl, 1 part methanol and 2 parts of other stuff to make it undrinkable. It doesn't list water content but I'm sure it has some by now. I'll add a few more cubes of dry ice!

Much of this is a grand experiment. I need to shrink stuff often but never seem to have the time to figure it out or have a bath ready. Now i will have.

Might have time to freeze some flowers and smash them with a hammer! Or deal with those rubber coated shafts that need turning, , or...

MattiJ
03-15-2017, 01:43 AM
I Dont know how much you pay or how long drive you have, but in some cases getting co2 ice from bottle is easier and cheaper. And you dont need to use more than necessary, rest of it can be used year later, unlike dry ice.

lakeside53
03-15-2017, 01:49 AM
3 miles.. our local supermarkets carry it! Last time I bought it year ago it as 99c a lb. I''m sure its more now, but not expensive.

MattiJ
03-15-2017, 02:08 AM
3 miles.. our local supermarkets carry it! Last time I bought it year ago it as 99c a lb. I''m sure its more now, but not expensive.
Sucks to be you, around here its anything from 20 to 100 mile drive, you have to order it 2 days in advance and smallest amount is something like 20 pounds and 100 usd! :mad:

Forrest Addy
03-15-2017, 05:11 AM
Lots of miscellaneous variables (heat radiation, mass of the work, dally time, drafts, spills, ambient temperature, etc) to screw up a precise answer so I suggest you simply roughly it out and add a safety margin. I'd start with a couple pounds of dry ice as being cheap enough and a little waste excess wont break the bank.

Besides, dry ice is fun to play with. Smudge under your eyes with soot, develop a hideous cackle, and wander the shop dragging a foot, chanting "Brains! Want brains!" carrying a coffee cup of dry ice in water drooling curdled looking vapor over the top.

You can't heat the cylinder? Generally simpler and you don't have to deal with the iron hard bark of condensate ice that instantly forms on parts at cryogenic temperatures. Move fast from bath to insertion. Rehearse every step.

lakeside53
03-15-2017, 12:37 PM
Rough was what I was aiming for.

I'm heating the cylinder block also. Can't use the wife's convection oven so I'm limited by how I can heat it. I did a test run with air blow heaters inside a box and in 3 hours got to to 190F evenly distributed. Not great but the limiting factor is the exit air temp of the heaters. I just need the extra differential the dry-ice bath provides. I get about 1.5 thou per 100F, have a 2 thou interference fit, worry about my interior bore measurements, Ra of the surfaces, the length of insertion (8 inches), the bark of ice that will form on the sleeve (thanks for that extra worry!), and much more. Anyhow, it's more of grand experiment that many result in a big hammer or press.

6PTsocket
03-15-2017, 01:08 PM
yep.. all a consideration! I just wanted to get into the zone.. I'll call it 2lb per gallon and never calc it again. This time a 5lb pack will do it.

I'll post pics soon... The bath is thin wall stainless in 3 inches of spray foam. Tiny losses there. Cylinder sleeve - yep - frozen in the freezer so same 58C drop required, but some compensation required. The Ethyl is actually a lab grade mix of 97 parts ethyl, 1 part methanol and 2 parts of other stuff to make it undrinkable. It doesn't list water content but I'm sure it has some by now. I'll add a few more cubes of dry ice!

Much of this is a grand experiment. I need to shrink stuff often but never seem to have the time to figure it out or have a bath ready. Now i will have.

Might have time to freeze some flowers and smash them with a hammer! Or deal with those rubber coated shafts that need turning, , or...
Aw, when you first started talking about ethel, I thought you had one of those copper things with the squiggly tubes behind your house. Denatured is no fun. LOL!!


Sent from my SM-G900V using Tapatalk

RichR
03-15-2017, 02:35 PM
I did a test run with air blow heaters inside a box and in 3 hours got to to 190F evenly distributed. Not great but the limiting factor is the exit air temp of the heaters.

I'd like to suggest a different approach. Cardboard box for an oven. Incandescent lamps (60 - 100 watts) for heaters. Box sealed and insulated
to keep the heat inside. If you wish, a small fan inside the box to circulate the air within. This keeps all the heat inside the box and allows it to
build up.

garyhlucas
03-15-2017, 02:59 PM
Years ago I visited a pump manufacturer in California. The pumps had herringbone gears about 12" wide and 6" diameter with a 3" shaft that stuck out both sides. His assembly method was a $12 dollar hot plate with the gear that got as hot as it would go. The shaft was in the fridge with the beer.
He dropped the shaft right thru. I asked if it ever failed. Yep, took a 200 ton press that barely managed to finish the job!

lakeside53
03-15-2017, 03:44 PM
I'd like to suggest a different approach. Cardboard box for an oven. Incandescent lamps (60 - 100 watts) for heaters. Box sealed and insulated
to keep the heat inside. If you wish, a small fan inside the box to circulate the air within. This keeps all the heat inside the box and allows it to
build up.

That's basically what I have right now. 100lb of cast iron 8 inches above a 1000w hot plate. Definitely better than my fan heaters which only put out 200F air. 220F (1.5 hours) and rising... if I get to 275F... I'll scrub using the dry ice.

CalM
03-15-2017, 08:37 PM
That's basically what I have right now. 100lb of cast iron 8 inches above a 1000w hot plate. Definitely better than my fan heaters which only put out 200F air. 220F (1.5 hours) and rising... if I get to 275F... I'll scrub using the dry ice.

Commercial Dry Ice is anything but... lots of H2O in the stuff sold at the corner market.

That makes all "heat content" calculation unlikely to be anything more than a WAG.

lakeside53
03-15-2017, 09:27 PM
I figured out how to get the Cylinder up to 300F so didn't need to go the Dry Ice route... Just my freezer at 3F for the liner.

I don't want to be accused of ever engineering this.. hmmm.. what is the combustion temp for cardboard. lol


http://i238.photobucket.com/albums/ff150/lakeside53/Quincy%20340/20170315_121811%20Custom_zpsrkwjvjqk.jpg (http://s238.photobucket.com/user/lakeside53/media/Quincy%20340/20170315_121811%20Custom_zpsrkwjvjqk.jpg.html)

Used a harbor Freight laser pointer/temp reader to check the progress though various flaps I cut into the box. Took 2 1/2 hours to get the 100lbs of iron up up to 300F.

Took the cylinder from the freezer and ... it just dropped in. yay...

http://i238.photobucket.com/albums/ff150/lakeside53/Quincy%20340/20170315_134604%20Custom_zpscjn9o3ul.jpg (http://s238.photobucket.com/user/lakeside53/media/Quincy%20340/20170315_134604%20Custom_zpscjn9o3ul.jpg.html)

2 seconds later it was impossible to move

Wait an hour for it to cool... then onto the BP for cleanup.
http://i238.photobucket.com/albums/ff150/lakeside53/Quincy%20340/20170315_145657%20Custom_zpssll5ufnu.jpg (http://s238.photobucket.com/user/lakeside53/media/Quincy%20340/20170315_145657%20Custom_zpssll5ufnu.jpg.html)


http://i238.photobucket.com/albums/ff150/lakeside53/Quincy%20340/20170315_152251%20Custom_zpspkg7daia.jpg (http://s238.photobucket.com/user/lakeside53/media/Quincy%20340/20170315_152251%20Custom_zpspkg7daia.jpg.html)

Don't you just love the original casting slag from 25 years ago?

lakeside53
03-15-2017, 09:31 PM
Bottom side.

Didn't bore it quite deep enough (it had already been over-bored 20 thou) and now will be taken back to stock, so vertical ridge has to go.


http://i238.photobucket.com/albums/ff150/lakeside53/Quincy%20340/20170315_154340%20Custom_zpsxxxllvja.jpg (http://s238.photobucket.com/user/lakeside53/media/Quincy%20340/20170315_154340%20Custom_zpsxxxllvja.jpg.html)


http://i238.photobucket.com/albums/ff150/lakeside53/Quincy%20340/20170315_162930%20Custom_zpswapxt76g.jpg (http://s238.photobucket.com/user/lakeside53/media/Quincy%20340/20170315_162930%20Custom_zpswapxt76g.jpg.html)


Next.. bore and hone to fit my old stock piston... with tax and freight that's nearly $600 I saved on the piston alone.

http://i238.photobucket.com/albums/ff150/lakeside53/Quincy%20340/20170315_165146%20Custom_zpsnl6hiszu.jpg (http://s238.photobucket.com/user/lakeside53/media/Quincy%20340/20170315_165146%20Custom_zpsnl6hiszu.jpg.html)

Oh..how did I bore the cylinder for the sleeve orginally? I was going to use my BP, a Criterion boring head and 5 and 10 inch 3/4 carbide Boring bars, changing the boring bar length half way though. Not enough Z travel or clearance for an 8 inch bore, and even if I had the Z clearance (need riser), at 20 thou passes it would have taken about 800 turns of the knee handle. urghh... My buddy with real machines felt sorry for me and let me use his big VMC. Was still painful to hit the bore number within a few tenths, but WAY better than I could have done on my BP. I was just going to get close then hone to size. Didn't need to; aimed for 3.1883; ended at 3.1886 (for the 3.1903 avg. sleeve O.D.). Spent more time calibrating measuring tools than machining, but...



Kaiser boring head in 40 taper. My 100lb of cast iron looks puny.

http://i238.photobucket.com/albums/ff150/lakeside53/Quincy%20340/20170313_10533820Custom_zps5qjaaw5x.jpg (http://s238.photobucket.com/user/lakeside53/media/Quincy%20340/20170313_10533820Custom_zps5qjaaw5x.jpg.html)

RichR
03-15-2017, 10:03 PM
Nice job. Looks like you didn't those pesky dry ice calculations after all.


hmmm.. what is the combustion temp for cardboard. lol
I think it's somewhere around Fahrenheit 451, isn't it?

lakeside53
03-15-2017, 10:07 PM
I'll need them "next time" ;)

Insulated bath container made!

http://i238.photobucket.com/albums/ff150/lakeside53/misc%20linked%20uploads/20170315_114904%20Custom_zpsxgcsei2l.jpg (http://s238.photobucket.com/user/lakeside53/media/misc%20linked%20uploads/20170315_114904%20Custom_zpsxgcsei2l.jpg.html)

danlb
03-15-2017, 10:30 PM
I think it's somewhere around Fahrenheit 451, isn't it?

That's how I remember the flash point for books too. I mean paper. Flash point for paper. :)

dian
03-16-2017, 12:13 AM
interested in what happens with the condensate in a shrink fit. no rust because no air i assume. but does it stay there, gets squeezed out, does it influence friction?

lakeside53
03-16-2017, 12:53 AM
Interesting....

At 300F can't imagine any condensate being trapped in there. I'm betting it all turns to vapor as the gap closes (It would not close perfectly symmetrically). In my case at 2 thou interference and two very good surfaces, the iron to iron pressure would be immense - can you crush water molecules into iron or does it all get heated so much it turns to vapor?

dian
03-16-2017, 03:52 AM
lets assume there is no heat involved.

Lee Cordochorea
03-16-2017, 09:07 PM
If there's no heat involved, there's no temperature change, no size change due to thermal coefficient of expansion, and therefore no shrink fit. :o

I suspect you wanted "not enough heat to evaporate the condensate." The question would then become "how many moles of condensate get trapped?" I ain't educated enough to go there.:confused:

dian
03-17-2017, 03:12 AM
didnt he shrink the part in dry ice?

RichR
03-17-2017, 03:34 AM
didnt he shrink the part in dry ice?

No, he was able to heat the other part enough so he didn't need part.

lakeside53
03-17-2017, 11:33 AM
But I did put it in my freezer - it iced up (thin film) immediately on retrieval. So yes, there was 300F for the cylinder and 3-4F for the sleeve.