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Author Topic: What material to use for a coolant tank?  (Read 3845 times)

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Offline Interested Observer

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Re: What material to use for a coolant tank?
« Reply #30 on: February 09, 2019, 02:06:52 PM »
Ref. reply #24
Rex,
While it seems easy to add a reinforcing strip to the model, it actually involves incorporating special contact elements between the original and the strip, which can be somewhat tedious and tricky to work with.  Besides, it is easy to say what the effect will be--the maximum stress will be marginally reduced and the location will move radially inward to where the ID of the strip winds up.  I don’t see much point in doing that.

Obviously, the 38ksi peak result of the elastic solution is useful to show where and to what degree there may be structural concerns, but 38 ksi would never be generated there since the yield strength of the aluminum is around 10 ksi.  The material would yield and larger local strains generated.  The problem is that the endload of the closure is having to be carried by the thin material at the radius in bending, which quickly generates high stresses--as can be seen since the same endload is carried in tension in the cylindrical wall at a much lower stress level.  To transfer the load into the cylinder without the bending, the closure needs to be much stiffer--added ribs across the end or a thicker, stiffer endplate.  (However, a thick/stiff endplate would not expand radially as fast as the cylinder wall, leading again to bending of the cylinder wall at the junction, although probably less so than the existing arrangement).  The tapered junction of a traditional elliptical tank head would also tend to transfer the load but with more compatible radial displacements.

As pressure is put into the tank as it stands, the stress at the radius would rise to the yield point, at which time the end cap would begin to permanently deform (balloon), changing the geometry, relieving the bending and moving toward a more tensioned stress state.  The question is, as pressure increases, whether the structure would obtain a stable geometry before the material ruptures.  (I may play around with an elastic/plastic analysis version of the existing model to see how it goes).

In any case, it would be prudent to do a proof test of the tank USING WATER to some pressure in excess of the service pressure before putting it into service.  Doing this in stages and observing deflections and any “permanent” distortion may give an indication of whether it can be made to work successfully as presently constituted.

Offline Stan Back

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Re: What material to use for a coolant tank?
« Reply #31 on: February 09, 2019, 07:10:30 PM »
Paul –

My solution was tested previously on a 250-MPH Monza.  Worked there – every time.  PM sent.  Give me a reply and we can talk.

Stan
Member of the San Berdoo Roadsters -- "California's Most-Exclusive Roadster Club".
Celebrating 67th anniversary of racing on the salt.

Offline jl222

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Re: What material to use for a coolant tank?
« Reply #32 on: February 09, 2019, 09:55:46 PM »

  Look at some of the large intercooler tanks they withstand a lot of boost and are not round. Some have added a strap
of metal overlapping along welds for reinforcement. We did expand and split welds on our rectangular tank when we torched thru the  head into  the water jacket and blew off water lines at engine. Not fun at 260+ when windshield fogged up. 2 chutes and 4 wheel brakes.

               JL222

Offline Rex Schimmer

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Re: What material to use for a coolant tank?
« Reply #33 on: February 11, 2019, 11:53:37 AM »
After reading IO's info it got me to thinking about going to a "radiator in a box" system as I believe that it is important to have a pressurized cooling system. I dug through some of my stuff and I found a nice Harrison liquid/air heat exchanger that I have had for quite a while, years ago I put some -10 AN fitting on it and it is just the right size to fit into our existing 12 inch dia tank. Another thing to get done before Bonneville! but probably a good idea. If I do it this year I will post some pics.

Rex
Rex

Not much matters and the rest doesn't matter at all.

Offline Interested Observer

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Re: What material to use for a coolant tank?
« Reply #34 on: February 11, 2019, 12:51:51 PM »
The FEA analysis was extended by considering the material to be bi-linear elastic-plastic.
Young’s modulus for the elastic portion of the stress-strain “curve” was 10.6e6 psi.
The plastic portion went from the 10,000 psi yield point of the elastic portion to a point at 18,000 psi and 0.25 strain as an approximation of a stress-strain curve since an actual curve for the material is unavailable. 
The von Mises stresses and total strain results are shown in the plots below.
The large red potion of the stress plot shows that that area had plastically deformed beyond the 10 ksi yield point up to a maximum of 10,242 psi (which is a point on the plastic portion of the curve).  The plot also shows that the end cap displaces a maximum of 0.188” axially, and that this displacement draws the radiused part at the corner radially inward.
The second plot shows the strain (or stretching) of the material with the maximum inside the radius and to the amount of 0.013.  This amount of strain is just beyond the yield point and well short of the assumed .25 strain at the assumed ultimate tensile load of 18,000 psi.
Upon relaxing the pressure load, the plastic portion of the tank would go into a more compressive state of stress, and the elastic portion would also acquire an array of residual stresses--not back to its original “unstressed” situation.  With a second pressure application the stresses would again return to substantially that of the original load.

Offline Sumner

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Re: What material to use for a coolant tank?
« Reply #35 on: February 11, 2019, 01:30:20 PM »
After reading IO's info it got me to thinking about going to a "radiator in a box" system as I believe that it is important to have a pressurized cooling system. I dug through some of my stuff and I found a nice Harrison liquid/air heat exchanger that I have had for quite a while, years ago I put some -10 AN fitting on it and it is just the right size to fit into our existing 12 inch dia tank. Another thing to get done before Bonneville! but probably a good idea. If I do it this year I will post some pics.

Rex



Has worked well for us...

http://purplesagetradingpost.com/sumner/Hooley%202013/13%20-%20construction%20menu.html

... and believe in all the advantages you mentioned in having a pressurized system on the engine side,

Sumner

Offline Stainless1

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Re: What material to use for a coolant tank?
« Reply #36 on: February 11, 2019, 03:27:36 PM »
Sumner... Happy Birthday my friend
Stainless
Red Hat 228.039, 2001, 65ci, MSA Bockscar Lakester with a little N20 
MSA Bockscar Lakester #1000 my fastest mile 245 and change, 84 ci turbobusa motor... but Corey's 233 MPH H/BFL record is still 3MPH faster than mine.

Offline SPARKY

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Re: What material to use for a coolant tank?
« Reply #37 on: February 11, 2019, 07:37:26 PM »
SS1  do you think Sum was trolling us for a happy birthday card? 

Happy B'Day Sum!!!!!!!!!!!!!1 :cheers:
Miss LIBERTY,  changing TKI  to noise, dust and RUST!!!

The # 1 issue is: TO KEEP THE REPUBLIC      
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"Security is mostly a superstition. It does not exist in nature, nor do the children of men as a whole experience it. Avoiding danger is no safer in the long run than outright exposure. Life is either a daring adventure or nothing."   Helen Keller

Offline Sumner

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Re: What material to use for a coolant tank?
« Reply #38 on: February 11, 2019, 10:08:54 PM »
SS1  do you think Sum was trolling us for a happy birthday card? 

Happy B'Day Sum!!!!!!!!!!!!!1 :cheers:

Thanks guys, but not really  8-).  The yard will put us in the water Wed.  Hope the rebuilt transmission and old diesel are good to go.  It has been a lot of work to go maybe 8 mph  :cry:

Sumner

Offline SPARKY

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Re: What material to use for a coolant tank?
« Reply #39 on: February 11, 2019, 10:28:40 PM »
How romantic Valentines day on the water  :cheers: to you, Dottie and crew
Miss LIBERTY,  changing TKI  to noise, dust and RUST!!!

The # 1 issue is: TO KEEP THE REPUBLIC      
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"Security is mostly a superstition. It does not exist in nature, nor do the children of men as a whole experience it. Avoiding danger is no safer in the long run than outright exposure. Life is either a daring adventure or nothing."   Helen Keller

Offline Stainless1

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Re: What material to use for a coolant tank?
« Reply #40 on: February 12, 2019, 08:38:05 AM »
Sum... most of us do a lot of work to go a couple miles and hour faster.... I'm guessing your boat was a 6-7 KPH boat 8 would be 15% worse case increase... most of us would give our left nut for that number  :roll:
Hope you had a great birthday... Stop by again sometime  :cheers:
Stainless
Red Hat 228.039, 2001, 65ci, MSA Bockscar Lakester with a little N20 
MSA Bockscar Lakester #1000 my fastest mile 245 and change, 84 ci turbobusa motor... but Corey's 233 MPH H/BFL record is still 3MPH faster than mine.

Offline tallguy

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Re: What material to use for a coolant tank?
« Reply #41 on: March 06, 2019, 11:30:30 PM »
If you do end up building a custom tank of aluminum, I strongly suggest a wall thickness substantially more than .062".  It's a lot easier to weld .125" thick aluminum, and weight probably isn't much of an issue for this application.  Keep all radii large, for pressure concerns, okay?  A round tank with domed ends (similar to an air compressor's tank) would be good.  I like the idea of using an existing steel tank, but would make sure it's a new one that hasn't rusted.  Good luck.  I wouldn't try to economize too much.  $39 or so seems too scary for me.  A SAE or ASME -approved tank is likely to be pretty safe.
« Last Edit: March 06, 2019, 11:33:14 PM by tallguy »

Offline Paul P

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Re: What material to use for a coolant tank?
« Reply #42 on: May 13, 2019, 08:06:48 AM »
I took everyone's advice and the result is shown in the attached photo.  As you can see I modified an old fuel tank I had in the shop.  My calculations show the tank to be around 21.6 gallons. The hold-down straps are 2"x1/8" steel straps that are bolted through the floor with 1/2" bolts and through plates underneath.  The remote electric water pump is a Meziere 55 gpm that will feed the mechanical pump on the motor.  The AN16 fitting next to the pump is for a drain.  I also installed my dry sump tank as you can see in the photos.  My total coolant capacity should be around 25 gallons if you include the radiator and hoses.  I know some advised to run a pressurized system but I am running it unpressurized for now.  I am going to rely on the volume to keep it cool.
« Last Edit: May 13, 2019, 08:11:20 AM by Paul P »

Offline SPARKY

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Re: What material to use for a coolant tank?
« Reply #43 on: May 13, 2019, 10:01:00 AM »
What size vent line did you go to--I noticed you said a 16 drain that size would make a good vent also
Miss LIBERTY,  changing TKI  to noise, dust and RUST!!!

The # 1 issue is: TO KEEP THE REPUBLIC      
   Center for Self Governance            tncsg.org     mrspowell.org

"Security is mostly a superstition. It does not exist in nature, nor do the children of men as a whole experience it. Avoiding danger is no safer in the long run than outright exposure. Life is either a daring adventure or nothing."   Helen Keller

Offline Paul P

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Re: What material to use for a coolant tank?
« Reply #44 on: May 13, 2019, 11:18:20 AM »
What size vent line did you go to--I noticed you said a 16 drain that size would make a good vent also

I was planning a 8 vent line.  I assume you think that is too small.