hollow evaporator?

[ellsworth]

is saw a few pics of aenigma's hollow blocks that he uses and decided to make one for myself for my new system.

its just a 1 1/4" pipe with 2 end caps on either end with a hole in the tope for a flare fitting. the cap tube will run thru the suction line and into the flare fitting for some nice sub cooling action.

i was wondering why everyone made a maze design block. i would think that a hollow design would work just as well, but the only draw back is that the mobo has to sit flat (which is no problem).

anyways, here is my evap that i brazed together sitting pretty next to my 2100+ ;) . i lapped the bottom flat from 120 - 800 grit. if it works it will be the cheepest and easiest block to make...haha i think it cost me <$5.

i need some feedback to those who have had expierience with hollow blocks vs maze blocks.

[ellsworth]

a pic of the underside

[TheDude]

Cool idea! How do you plan to connect it to cpu? How about insulation? Just wondering what ideas you have on it. Thanks:D

[ellsworth]

well i have to give all the credit to aenigma, it was his idea and i think he uses one. (just havnt seen him on in a long time to ask him how it performs)

insulation is a breeze becasue all you need is some pipe insulation or insulation tape to wrap it around it.

connecting to the cpu...havnt quite decided exactly but i think im just going to use the old piece of acrylic hold down method, or im going to make an insulation box like bowman did. actually i already made a prototype metal insulation box similar to bowmans, but the hold down i made doesnt work quite right so i will be making another one in the near future.

im surprised nobody has gond this route...its so cheep :D
hope it performs well. it seems like flooding the evap or liquid slugging would occur very easy. is this going to be a problem?

i cant test anything untill i get home in mid may. :(

[TheDude]

Best to wait for the master...Bowman on this. I have seen posts where people advocated the hollow evap like yours. Bowman has made his own. I'm sure he will see this before long and jump in.

[bowman1964]

Originally posted by TheDude
Best to wait for the master...Bowman on this. I have seen posts where people advocated the hollow evap like yours. Bowman has made his own. I'm sure he will see this before long and jump in.

yea i just back into work,been on the road all day .
but anyway.

ok i have made a hollow block design.and i was very disappointed in it's proformance.major problem i had was heat removeal.
ok now i have friends that use hollow blocks and they work great to learn with.but other than having a drawback of having to lay flat,they dont work as well.let me try to explain why.

refrigerant needs to boil off( evaperate) to cool.now a maze design gives many times the surface area and keeps the refigerant moving and evaperating.a single hollow block does alow it to evaperate but has little surface area so a very poor way to transfer heat to the refrigerant.and that is what you need.
there is nothing wrong with a hollow block,it is easy and will work.
but i havent seen them proform any where close to a maze or spiral design.
the heat of todays cpu's need the most effecient heat removal possable,and i just dont like the proformance a hollow block gave me.all though my hollow block did give close to the maze ,no load temps.when i applied a heat load there was no compairison.
but i know aenigma got his better by adding some area to the inside of the block,to aid in heat removeal.
i still like the more surface area.

[ellsworth]

well im glad i was informed before i started testing, you saved me a lot of frustration heh.

i am aiming at the best performance i can get out of a single stage phase change system so i might as well look into having a block milled.

can you point me to some good designs to look at? i might be able to "mill" my own with a drill press if the channel pattern is simple enough to do without a cnc.

thanks for the input bowman.

[bowman1964]

since i have these hosted myself i dont mind reposting the pics i showed in another post...I hope this helps my friend.



ok here are two of my designs.same block differant view.these are to my multilayer blocks i designed.http://members.fortunecity.com/ajr011/bowmanscoolingextreeme1/Scan10003.JPGhttp://members.fortunecity.com/ajr011/bowmanscoolingextreeme1/cnc.jpg

[Tweaked!]

ellsworth, we've also got another member around here who has shown a very good talent at milling blocks. He's Morphling1, and he's made some awesome water cooling blocks. He's located in belgium if I remember correctly, and i plan to eventually have him make mine for me. Give him a shout, he might be willing to create whatever design you think will work for you.
As far as your current design goes, might be worth giving a shot if you're able to add some directional channels or fins to the interior of the canister. But like Bowman said, it's all in the exposed surface areas, inside the block and out. By adding the "maze" or "channeling" effect to it, you're adding exposed surface to coolant area, and adding a turbulence factor in there which aids tremendously.
Even in residential air conditioning, the insides of the copper lines of the coils and linesets are rifled to constantly keep the coolant changing it's contact within its properties. I hope that made sense, it did in my head anyways;) :cool:

[nyTroX]

When you clamp that down to the cpu, won't it bend a bit and lose contact with the cpu in the middle of the hollow block? If you brazed it, wouldn't the copper be somewhat annealed and soft enough to bend easily and be tight at the corners, and somewhat bowed up at the middle?

[ellsworth]

If you brazed it, wouldn't the copper be somewhat annealed and soft enough to bend easily and be tight at the corners, and somewhat bowed up at the middle?

well i thought of that so when i was done brazing i lapped the bottom surface to get it nice and flat/smooth, but i was thinking that when i added pressure it might bow in and out with changing vaccum and pressure...(not good)

thanks for the drawings bowman :D
i will use your drawings for some ideas.
how wide/tall is your block bowman? just to get some perspective.
is it necessary for 2 layers?? thats a lot of copper hah.
is a maze shape better than a spiral since it has more turns? i guess more turns would add turbulance which would be a good thing i would imagine.

tweaked: i think im going to see if i can do it myself, and if i cant do it or i cant find the right tools i might give him a shout, thanks for the suggestion ;) his water blocks are superb.

i think i will be ordering some copper soon and drawing up some ideas. i like a round block since its so easy to insulate.

[bowman1964]

Originally posted by ellsworth
thanks for the drawings bowman :D
i will use your drawings for some ideas.
how wide/tall is your block bowman? just to get some perspective.
is it necessary for 2 layers?? thats a lot of copper hah.
is a maze shape better than a spiral since it has more turns? i guess more turns would add turbulance which would be a good thing i would imagine.


the sections you see are 2"x2"x3/4" then milled.

i used mulitlayer because of the need for effecient evaperation of the refigerant.but i am not sure if all that is nesssary.sprial will work very well also.
i just decieded if i was going to make it from scatch with no other design to go on.i would use all that i know about water blocks,refigeration,and combine it into a design i thought would work.
i was the first person to ever design a mutilayer block.but it works.it may be a overkill but i normally do go overboard sometimes

[ellsworth]

thanks a lot for your input.
i think im going to make mine 2"x2"x1" with a similar design, but a single layer most likely unless i can find a mill. in that case i might do 2 layers thinner layers.

i cant do anything untill i get home from school besides make a few phone calls. :(

[aenigma]

Ok looks like I need to clear this up.Hollow blocks do work well when used what I like to call, the right way. ;)
Bowman used it in a conventional setup, motherboard mounted in a case.I use mine with my mother board laying flat, I don't think -32c loaded cpu die temps with my xp1600@1.94 1.85v is performing very poorly.The one problem with pipe caps is they warp from the pressure, the bottom of my block is convex.

Hollow blocks work great, I think -32c is pretty good considering my block has a convex bottom and my phase change system had too much capillary(12 feet of .026" :eek:).

Man I haven't been on the forums much, just taking a break for awhile.I am taking a break with my recent system as well, I got bored with it and spring is just so nice.

[ellsworth]

i had planned on having the motherboard lie flat for my new case design, so maybe ill give it a go just for kicks...it couldnt hurt.

if it doesnt work as well as planned i could just resort to making a maze type block, no big deal.

aenigma: my hollow block is 1 1/4" diameter and if i recall correctly yours is 1" and you said yours was convex. well mine is bigger a quarter of an inch bigger so it should be subject to higher forces when the system equalizes...maybe making it warp even more.

(off topic) how long is your cap tube aenigma...or how long SHOULD it be ;) ? i have a 4000btu compressor, and will be using propane and have plenty of .026" cap tube. my setup is very similar to yours if i remember it correctly.

[aenigma]

Well this is my old system, tore it down long ago.I have built anew one, just got tired of tinkering with it(fully built, just need to make a new evap).
I think the pipe caps are about 1/16" thick, pretty darn thin.
I had the whole roll of capillary on the system, I was too lazy to get the perfect ammount. :)
I think it was 12 feet?Should have been about 8 feet i'd say.

[]JR[]

http://www.phjrw.34sp.com/evap1.jpg
http://www.phjrw.34sp.com/DCP_1415.JPG
http://www.phjrw.34sp.com/DCP_1416.JPG

opposing C style block although my channels might be too thin, its simply flattened out copper pipe bent round various round things then soldered to the base to make the channels...

]JR[

[bowman1964]

Originally posted by ]JR[
JR[

good to see you over here.

these guys would love seeing your suff.as i do..:D

i havent told you yet but i like the design,i think it will work pretty good.i cannt wait until you get it going.


off topic.
i see we are still waiting on the startup circuit,sorry dude i guess he had some things come up.if he gets it going i will try and post a guide with his help ,so none of us will have this problem.

again good to see you

[aenigma]

Hey ]JR[.Nice block, looks great.Ssjwizard had an idea for a block that also used concentric channels like that.You could increase the height of those channels and put a plate over it with a small hole in the center for the capillary to go through, then 2 small holes on each side of the block on the outer channel for the suction line and it would work in a traditional setup.

[]JR[]

Its a copy of one of my home built waterblocks, just smaller :)

It has a plate with holes on it already aswell, it was always the plan, that pic was just showing the channels its a bit difficult with a copper plate ontop :)

Do i need to put anything like acid or anything to remove gunk before i finally stick it together?

EDIT or do i really need to make the channels higher?

]JR[

[bowman1964]

Originally posted by ]JR[
Its a copy of one of my home built waterblocks, just smaller :)

It has a plate with holes on it already aswell, it was always the plan, that pic was just showing the channels its a bit difficult with a copper plate ontop :)

Do i need to put anything like acid or anything to remove gunk before i finally stick it together?

EDIT or do i really need to make the channels higher?

]JR[

well i acid all my blocks then sand blast them.sand blasting cleans and i feal roughens the surface to aid in heat removal.

as far as the channels go.you have already built this one.do'nt change it untill you get to test it and see how it does.

[aenigma]

Yeah I always use acid to clean my blocks, your block looks very clean.When you braze a block they turn black.
Don't change your channel design, if you are going to change it just make a new block.

[]JR[]

What sort of acid, im sure ive got some sulphuric although its so strong itll wipe out the whole thing in minutes :D

Tomato ketchup seems to be fairly effective @ cleaning copper tho?

]JR[

[bowman1964]

Originally posted by ]JR[
What sort of acid, im sure ive got some sulphuric although its so strong itll wipe out the whole thing in minutes :D

Tomato ketchup seems to be fairly effective @ cleaning copper tho?

]JR[

I use what ever i have on hand.i use diluted sulphuric acid mostly.but just look for aluminium wheel cleaner thats cheap and effective.

[aenigma]

Yeah I use eagle one mag wheel cleaner.