Project Codename: Medusa, [*56k Beware*] Options

[Jabo]

Project codename:
‘Medusa’ or passive radiator design development.


Enthusiast level personal computer cooling solutions are well ridden with plethora of different problems and it is always a juggling act between price, noise, size and performance.
Overclocking community is the one that suffers the most from excessive noise problem since almost always at the end of any cooling solution sits a heat exchanger dumping waste heat into atmosphere (geothermal cooling aside).
There are ways of reducing noise levels as we all know of i.e. use of large fans at low speeds, use of sound dampening materials



My Chieftec's side panle lined with cut carpet tile - reminder from air cooling days


or even building special sound attenuating enclosures




Jabo design Cooling Tower TM


Using total water cooling solution (which includes water cooled PSU as well as CPU, GPU, NB) helps great deal to control sound by limiting noise source to one single place, your radiator. When you're done with all of the above you may be tempted to think whether there are even more advanced ways to get rid of the Boeing 747 take-off noise simulator from your PC workstation. The best way is to drill some holes in external wall, put pipes through and place your rad/fans assy outside. Advantages are two-old, no noise and almost always lower temps (unless you have AC in your room that is ).

The next step is usually to improve cooling efficiency by either burying substantial size tank into ground (petrol drum should do) or installation of geothermal cooling system (lattice of pipes over an area of land sunk quite shallow or vertical pipes installed in deep bore holes).
The above designs could be quite complicated and impossible to implement for most of hardcore cooling enthusiasts, even thou they are the most effective and the ‘greenest’ design possible (I am researching know feasibility of use photovoltaic cells and micro wind turbines to power my power hungry TEC ‘puter)

The ultimate in PC cooling and noise cancellation is combined chilled water and direct phase change cooling using remote heat exchange plant * slobber *.

Getting back to earth… I started to think about improving existing design of radiators and decided to go for passive cooling solution for my double (soon to be triple) TEC system. I just had enough of fan noise, period . Since TEC systems generally run hotter coolant than plain WC ones I thought it had some chances of success.

The key to my design lies in massive water-to-copper contact surface area. Regular radiators have lots of fins making large air-to-copper contact area with very small comparatively to coolant-to-copper contact area. To achieve this I decided to use manifolds and 8mm microbore soft copper tubing, 50 meters of it to be exact.


Wilo Gold 50 Domestic Central Heating Circulating Pump and 8mm coil

22m/6x8mm manifold

Soldered manifolds forming 'feed branch'

Large number of ‘branches’ was used to minimise head loss and to allow coolant longer time in contact with copper.
Now, after the whole thing was done I realised that with my current pump I do not need to worry about head loss and I’d be better off with much smaller number of longer ‘branches’. This would achieve even longer time period spent inside branch but at much higher coolant velocity creating much thinner boundary layer and substantially boosting thermal transfer rate (impingement technique is based on reduction of boundary layer simultaneous increase in coolants density over area unit in time unit).
Having large amount of coolant in direct contact with copper and lots of copper to tuck away I came up with this solution


One of the 12 pieces

The ideal would be to spread the pipes horizontally as wide as possible but it is rather unpractical approach, don’t you think? So I did this












and the whole thing in it's place

I also decided I want to hard plumb parts of my system to lower resistance at bends and connections


This connects GPU (and system) out with pump

It was my first attempt at Propane-Butane torch welding and my templating skills need some more practice (I did not do full ‘dry’ fit to check if all is perfect and ended up with bad line out from my vid card which screams for redoing. It exerts lots of force on my Swiffy block it ruins contact surface between GPU and cold plate which rose my temps by 10 degs C).

I am happy with results. Before Medusa I was using Saab heatercore installed inside my Cooling Tower and I was getting water temps of 26-28 degs. C and CPU temps as measured by WinBond util. of –4C idle and 9C load.
With Medusa I am getting 3C idle and 13C full load temps with water hovering about 38C – not a single fan pushing air over Medusa and it sits in the worst possible location being corner of dining room, next to radiator… For completely passive system I think it’s impressive.
Of course I could not help myself and I aimed domestic fan over it. CPU temps went as much down as –7C! (water 26C).

Improvements to be incorporated into Medusa 2 Project:
1. Use 4 way manifold – decrease in system’s flow cross-section inside Meduse will cause higher coolant velocities and much better heat transfer due to thinner boundary layer
2. Each branch would be full 20 meter coil wound in decreasing-diameter-spiral fashion over 2 meter high cone-like template – vastly increased coolant-to-copper contact time period and ‘stack effect’ occurrence (estimated, don’t know if temps are going to be high enough for ‘stack effect’ to happen)
3. Smaller foot print of radiator unit
4. Killer looks

What do you think? Would you change anything / improve something?

This post has been edited by Jabo: Nov 20 2004, 01:55 PM

[Jabo]

Ufffff, it is up and runing, finally, enjoy the ride and please be gentle with your flaming

EDIT: Great thanks to Marci for help and pictures hosting space:)

[Halloween]

Strewth! Go for it fella!

Love the plumbing!!!

How is it for gettin rid of airpockets?

[Jabo]

It is dead easy to check for any since by touch one can imeddaitely establish where air is. All you need to do is shake it baby, shake it like a Polaroid picture!
He he he, and put it upside down like twice, all with pump runing and you sorted.

While changing coolant I need to do a 'live transfusion' - pump is running at low speed sucking fresh stuff from container and discharging crap the other end - very humane

[Silent]

Nice rad. I had the same idea but using 2 meter lengths of striaght pipe and a larger manifold and about the same length of pipe in total. My idea was to keep it compact but instead I didnt make one and am hoping to move my heatercores out into the garden.

Im interested in where you got the pump, Ive been following the debate on its performance at proforums, and Im thinking of getting one to (as nowhere has stock of the DD D4 atm). Do you know if they make one made of brass/other other material that doesnt corrose? or if it could be modified to a brass housing (I can make one, depending how complicated the insides are).
Is the pump submersable - not for sucking coolant I mean to cool it down, It runs very hot yes? Are the electric parts of it waterproof?

How much did the 50meters of copper cost? Also is the tubing easy to bend by hand or do you need some kind of tool to do it (Ive only used hard copper pipe).
Does the pump give almost mains pressure for the water?, maybe use two in parrelell for really high flow rate

[Twisted]

all I can say is I feel for ur wife (u do have 1 or has she left already) also if u gt kids wot r the chances of them goin over ther and ripping it 2 pieces!!???

[Gav2k]

very nice idea, just need to park it outside up high where the wind can get to it!

[NeKraNomaKoN]

heres an idea for ya.

dig a hole in the ground outside big enough to accept the medusa then fill it with cement mount the medusa Upside down in the cement so ur in/out tubes r exposed run some pipin into ur house with in/out attachments then stick ur pc close enough to the in/out so u can attach ur pc tubes to it and voila the cement is cooled by the ground and the water runs through the cement adding its own effective cooling a lot of messin around but just an idea.

my 2pence.

[Jabo]

Nice rad. I had the same idea but using 2 meter lengths of striaght pipe and a larger manifold and about the same length of pipe in total. My idea was to keep it compact but instead I didnt make one and am hoping to move my heatercores out into the garden.

Im interested in where you got the pump, Ive been following the debate on its performance at proforums, and Im thinking of getting one to (as nowhere has stock of the DD D4 atm). Do you know if they make one made of brass/other other material that doesnt corrose? or if it could be modified to a brass housing (I can make one, depending how complicated the insides are).
Is the pump submersable - not for sucking coolant I mean to cool it down, It runs very hot yes? Are the electric parts of it waterproof?

How much did the 50meters of copper cost? Also is the tubing easy to bend by hand or do you need some kind of tool to do it (Ive only used hard copper pipe).
Does the pump give almost mains pressure for the water?, maybe use two in parrelell for really high flow rate

Yeah, the road from the idea into actual device is the hard part
I went for this sizes due to large surface area of copper enhancing copper-to-water and copper-to-air heat transfer rates. It has 1256000mm^2 of surface area, more than most rads
I thinks I'll dig a pit in my garden fill it in and enjoy sub-ambient cooling at it's best

Pump is to be bought at almost every DIY store in UK. Alternatively you can go for many different brands, best being Grundfos.
Wilo is not submersible it is made to be run in-line and if you want to cool it using water you'd have to do a custom waterproofing job on electric box. Grundfos does fully submersible pumps but they cost much more:( I was to buy pump now I;d havd gone for Wilo Gold 60, more powerful than I have now for only fraction of a price more.
Considering finish of the pump, imho the best way around it would be sand blast it and brass plate it or chrome plate it. Making new housing does not seem to be feasible.
Hmmm while doing new finish jobbie you could polish insides of the pump making it run smoother and cooler:)
Speking of which, it runs hot when at top speed settings, anything below (two more speeds) is perfectly fine. I run mine wth slow fan blowing at it as you can see on the picture:)

Copper is quite cheap, I bought mine (as all the rest of plumbing stuff) at B&Q. If I remeber corectly I paid £35 for 2no20mx8mm coils and 1no10mx8mm coil.

[Jabo]

heres an idea for ya.

dig a hole in the ground outside big enough to accept the medusa then fill it with cement mount the medusa Upside down in the cement so ur in/out tubes r exposed run some pipin into ur house with in/out attachments then stick ur pc close enough to the in/out so u can attach ur pc tubes to it and voila the cement is cooled by the ground and the water runs through the cement adding its own effective cooling a lot of messin around but just an idea.

my 2pence.

The idea is fine m8:)
I'd have done a tad diff thou.
Dig a hole, as big as necessary in plan to recieve medusa and piping (hard plumbing) and roughly 600-800mm deep. Along the walls I'd pile in some steel reinforcement rods to keep side walls from collapsing and still keep the ground water flow. Next step is filling the botom with quite thick grit fill, sth like scottish pebbles (can buy them at garden centres for your garden paths) to 100mm deep, then another 100 is filled by coarse sand. On top of that Medusa is going to sit. Next fill the pit with Medusa in with fine sand. Alternatively, befor putting Medusa in and filling the pit it could be lined with fully water permeable membrane to allow for easy future maitenance. The pit then would be covered with a lid of some description:)

When I do Medusa 2 the current one is going to the ground

[kane75]

Out of interest, what is the overall dimensions of the thing? And what size do you expect Medusa 2 to be?

Tis a great thing you have made, and is a fair bit cheaper than the Zalman case

[Jabo]

Out of interest, what is the overall dimensions of the thing? And what size do you expect Medusa 2 to be?

Tis a great thing you have made, and is a fair bit cheaper than the Zalman case

I'll get the dims when I get home.
Funny ypou mentioned Zalman's heatpipe dream.
I checked RRP, guess how much? £898 !!!
I could buy parts for the whole rig AND build Medusa for that dough! LOL

[Jabo]

Very cool idea dude, thats a really interesting project. Cant wait to see your plans for #2

Keep up the good work

Cheers mate! Gonna be around summer time (need to send family for holidays to have some peace and quite.

P.S. Yes, I still have them, they have not left me as yet. Instead my wife demanded a laptop for herself and she spends hours on message boards. It looks lke this thing is quite contagious...

[Jabo]

I've some other ones waiting on my h'drive to be uleashed. Not so spectacular but should cause some stirr too:) (insulating material for Pelts) and water block kicking the snot out everything what's on the market atm...
Sadly, the latter depends on the sorry state of my bank balance (Little Modders have lots in common with Black Holes, at least whan it comes to dough;) ).

[Jabo]

At the moment Medus is 500mm wide x 650mm deep x 500mm high.
Filled with water is a tad heavy I must admit but hey, don't we all need some excercise?

Yes it is going to be even BIGGER but cheaper. I may increase pipe lenght by 10meters but that's not what is going to make Medusa 2 tick. I'll be trying to increase heat transfer rate substantially by thinning down coolant's boudary layer.
Medusa2 is going to have smaller footprint but will be taller. I wnt to be able to take it LAN you know.... *me smiles wickedly*

[Guest_Jabo's wife_*]

all I can say is I feel for ur wife (u do have 1 or has she left already) also if u gt kids wot r the chances of them goin over ther and ripping it 2 pieces!!???

Here's Jabo's wife Thank you, I appreciate your concern There is an increasing chance that I will actually do something similar to what you've suggested Or our son will
This thing has taken over our living room Is there any way you can convince Jabo to buy a shed and move there??

[Jabo]

HELP! She followed me here! I am DOOMED! H E L P !

P.S. She's got quite clever plan of buying me a garden shed, fully plumbing it, bed, fridge armchair, tv + my putter = getting rid of Jabo's mod shop and Jabo himslef that is ....

[Marci]

I know we'd be talking MASSIVE flow restrictions here, but with the way you've utilised the manifolds not so much of an issue, but have you thought about adding capillary tube runs within the network to further increase the surface area of water in contact with copper??

Either across the existing loops...



Or replacing the existing loops...



So for each loop, rather than having a static bend of pipe, you stop short of the loop, take a cluster of... er... (maths time... 0.09" OD Cap Tube vs 8mm Copper Pipe = 2.2mm OD) about 20 lengths of cap tube, jam them into the end of the 8mm pipe, braise em or solder em in, bend em round to next section and same again...

Dunno if it'd work or not tho... I'm just theorisin as per usual.... but, with the cap tube being much finer you can incorporate tighter bends whilst retaining the same (if not higher!!) total area of copper, thus allowing you to fit it all into a much smaller space....

[Jabo]

I can see where are you coming from, more and more time spend on phase change recently huh?

What you drew looks similiar to this

Originally I was thinkin 6mm piping but costs were prohibitive...
I'd love to do what you are suggesting but first of all I do not know how to braze (no equipment to do it neither). Secondly costs... I wanted it be quite cheap or better, good value for money and affordable to everyone.
Lastly this design is using off-the-shelf parts readily available at any DIY store here in UK. 6mm pipe is the thinnest you can go there...

Nuff of being negative here!
I tip my hat to you Sir since you gave one great idea of how to increase copper-to-air surface area. What's more, it is going to cost next to nothing, requires no tools (pliers...) and is dead easy to do.
Your drawing on which drew lines connecting two arms of bent pipe?
Imagine thin copper wire woven on 8mm piping... like a spider web... *me runs slobbering to nex door Wicks*.
Here comes Marci inspired Medusa mod!

[Marci]

What you drew looks similiar to this

Yep, just with smaller cap tube and more of it! It'll solder, doesn't have to be braised... I just always say braise cos with the phasechange stuff we braise everything to be safe, but fer watercoolin plain old soldering'd do the trick... But yeah, to get the cap tube means you need access to a refrigeration supplier (www.dean-wood.co.uk fer instance)

Like the sound of the spiderweb... should improve overall rigidity of the structure as well as copper to air... but for optimum thermal contact I'd recommend either lots of thermal compound where wire meets/wraps round the tube, or solder the wire directly to the tube...