Author Topic: What material to use for a coolant tank?  (Read 11768 times)

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Offline Rex Schimmer

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Re: What material to use for a coolant tank?
« Reply #15 on: February 06, 2019, 01:26:04 PM »
I find it interesting that so many guys do not run pressurized cooling systems, especially on blown or turbo engines. As we all know cooling system water pressure increases the water boiling point and is especially critical around exhaust valves. Duke and I run a round 10 gallon tank made from 3003 aluminum, with crowned tank ends and a 17 lb pressure cap never had a problem but we do run methanol which really keeps the engine cooler. At 20 psi the longitudinal and hoop stresses are approx. 1000 psi and 2000 psi respectively and the material yield strength is  10,000 psi for annealed condition. The end caps are domed and the weld joint is designed to be in tension so its load is less than 3000 psi which gives us a safety factor of over 3:1 on yield strength. Based on these numbers we feel confident to run a pressurized cooling system.

Rex 
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Offline Paul P

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Re: What material to use for a coolant tank?
« Reply #16 on: February 06, 2019, 02:06:42 PM »
I find it interesting that so many guys do not run pressurized cooling systems, especially on blown or turbo engines. As we all know cooling system water pressure increases the water boiling point and is especially critical around exhaust valves. Duke and I run a round 10 gallon tank made from 3003 aluminum, with crowned tank ends and a 17 lb pressure cap never had a problem but we do run methanol which really keeps the engine cooler. At 20 psi the longitudinal and hoop stresses are approx. 1000 psi and 2000 psi respectively and the material yield strength is  10,000 psi for annealed condition. The end caps are domed and the weld joint is designed to be in tension so its load is less than 3000 psi which gives us a safety factor of over 3:1 on yield strength. Based on these numbers we feel confident to run a pressurized cooling system.

Rex 
Who rolled the aluminum for you?  I would prefer a round tank but I am having trouble  finding someone who can roll it.

Offline Glen

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Re: What material to use for a coolant tank?
« Reply #17 on: February 06, 2019, 02:50:39 PM »
Where are you located Paul P.????
Glen
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Offline Rex Schimmer

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Re: What material to use for a coolant tank?
« Reply #18 on: February 06, 2019, 06:46:52 PM »
Paul,
I cut a piece approx 38 x 20, divided the piece in the 20 inch direction approx 1 inch apart, 36 lines, and then used my tin break and incrementally bent along each line until the ends came together. I then put the largest radius wheel in my little english wheel and ran over each of the bends to make it a little more round. Made a quick buck from two pieces of plywood cut to 12 inch diameter with a piece of 4x4 between them and then a couple of ratchet tie downs around it to hold the ends together and tacked with the TIG welder, then had my son Duke, weld together. All welds except the final top to the tank are welded from both sides. Used one of the 12 inch dia plywood parts of the buck to make the end pieces, started with a piece of aluminum cut to about 13 inch dia, then rolled a slight dome with the english wheel and annealed the edges, routed a 1/2 inch radius on the 12 inch plywood and beat the edges of the aluminum over with a soft hammer. Messed around until I got a nice fit and Duke welded complete.
Rex
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Offline Stan Back

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Re: What material to use for a coolant tank?
« Reply #19 on: February 06, 2019, 08:05:55 PM »
We have an 18-gallon cubicle tank situated mainly over the right side of the rear end of our street roadster (offsetting the driver).  It's not under pressure, but has a relief outlet to the back of the roadster.  It's built of 1/8-inch steel with a 1/4-inch bottom.  It's successfully cooled the car 5+ miles time after time.  In fact, the same water is there after 15 years.  Maximum temp recorded in the engine at Bonneville was about 190º.  We've been choking it off with the gate valves to maybe get a few more horsepower at El Mirage.

Water, and its container, is cheap ballast. And, if you fill it up, it doesn't slosh around much.

Sometimes methinks some overthink all this (why not a refrigeration unit inside a radiator inside a tank, back 18% of the driver, controlled with a digital thermostat that allows a printable readout that we can put on Facebook?).

Stan Back
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Offline Paul P

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Re: What material to use for a coolant tank?
« Reply #20 on: February 08, 2019, 01:18:52 PM »
Where are you located Paul P.????

I am in Oklahoma City. 

Offline Paul P

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Re: What material to use for a coolant tank?
« Reply #21 on: February 08, 2019, 01:24:46 PM »
We have an 18-gallon cubicle tank situated mainly over the right side of the rear end of our street roadster (offsetting the driver).  It's not under pressure, but has a relief outlet to the back of the roadster.  It's built of 1/8-inch steel with a 1/4-inch bottom.  It's successfully cooled the car 5+ miles time after time.  In fact, the same water is there after 15 years.  Maximum temp recorded in the engine at Bonneville was about 190º.  We've been choking it off with the gate valves to maybe get a few more horsepower at El Mirage.

Water, and its container, is cheap ballast. And, if you fill it up, it doesn't slosh around much.

Sometimes methinks some overthink all this (why not a refrigeration unit inside a radiator inside a tank, back 18% of the driver, controlled with a digital thermostat that allows a printable readout that we can put on Facebook?).

Stan Back
Holding Street Roadster Records for 17 Years with a Sledge Hammer
(Your Results May Vary)


That is the kind of feedback I needed.  If yours works mine should do the job.  I do have a tendency to overthink things but once I have thought it through I always want the simplest solution.   Simple means less to go wrong.  What size motor are you running?

Offline Paul P

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Re: What material to use for a coolant tank?
« Reply #22 on: February 08, 2019, 01:28:21 PM »
We have an 18-gallon cubicle tank situated mainly over the right side of the rear end of our street roadster (offsetting the driver).  It's not under pressure, but has a relief outlet to the back of the roadster.  It's built of 1/8-inch steel with a 1/4-inch bottom.  It's successfully cooled the car 5+ miles time after time.  In fact, the same water is there after 15 years.  Maximum temp recorded in the engine at Bonneville was about 190º.  We've been choking it off with the gate valves to maybe get a few more horsepower at El Mirage.

Water, and its container, is cheap ballast. And, if you fill it up, it doesn't slosh around much.

Sometimes methinks some overthink all this (why not a refrigeration unit inside a radiator inside a tank, back 18% of the driver, controlled with a digital thermostat that allows a printable readout that we can put on Facebook?).

Stan Back
Holding Street Roadster Records for 17 Years with a Sledge Hammer
(Your Results May Vary)





I had someone recommend using a fuel cell since I'm not going to run it under pressure.  What do you think?

Offline Interested Observer

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Re: What material to use for a coolant tank?
« Reply #23 on: February 08, 2019, 02:03:07 PM »
Ref. replies #15 and #18
Rex, and other interested parties--
Working backwards from the data you stated, it appears your tank is 12” in diameter with 0.060” wall aluminum material.  The photo doesn’t very well show the 1/2” radius mentioned at the joint of the cylinder and head, but I assumed it was there per your description.  While the radius is much improved from a sharp corner, it doesn’t really constitute a spherical or elliptic tank head insofar as nicely accommodating stresses from internal pressure.  Taking these dimensions, and assuming a 1/2” crown to the lid, an axisymmetric finite element model was made of the upper quadrant of the tank and was subjected to 20 psi internal pressure.  As you can see from the jpeg’s attached (if I can do that correctly), Pd/2t isn’t the last  word on the stress distribution of the vessel.
Given the number of commercially available pressure vessels of various sorts (air tanks, scuba tanks, beer kegs, gas transport tanks, etc., etc.) that are necessarily built to ASME or other criteria, it seems much easier and confidence inspiring to re-purpose such a thing as opposed to making one from scratch.  Pressure vessels are trickier to do correctly than they might appear to be.

Offline Rex Schimmer

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Re: What material to use for a coolant tank?
« Reply #24 on: February 08, 2019, 02:52:14 PM »
I.O.
Thank you very much for the FEA on our water tank! Looks to me that we might need to add some additional material in the area of the radius. Another thing on the "to do" list!
As long as you have the model what would it look like if we added an aditional ring of .062 in the area of highest stress?

Thanks again!

Rex
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Offline WOODY@DDLLC

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Re: What material to use for a coolant tank?
« Reply #25 on: February 08, 2019, 04:18:10 PM »
All models are wrong, but some are useful! G.E. Box (1967) www.designdreams.biz

Offline ronnieroadster

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Re: What material to use for a coolant tank?
« Reply #26 on: February 08, 2019, 09:55:24 PM »
I.O.
Thank you very much for the FEA on our water tank! Looks to me that we might need to add some additional material in the area of the radius. Another thing on the "to do" list!
As long as you have the model what would it look like if we added an aditional ring of .062 in the area of highest stress?

Thanks again!

Rex


  Run a no pressure system and you eliminate the stress like many of us are doing just saying.  :cheers:
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Offline will6er

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Re: What material to use for a coolant tank?
« Reply #27 on: February 08, 2019, 10:14:11 PM »
I run a non-pressurized rectangular (mostly) tank. It used to be the fuel tank. It has worked pretty well, but is rounder since I holed a piston.

Will Willis  #6302

Offline SPARKY

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Re: What material to use for a coolant tank?
« Reply #28 on: February 09, 2019, 12:15:51 AM »
I have run a fuel cell for cooling water for my radiator in a box and can tell you from first hand experience---you better have a VERY big vent if you ever start retuning steam to it--they blow up like a balloon and can definitely destroy body panels,  which then can induce aero steer which may lead to an unexpected high speed exit of the track  :-D
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Offline WOODY@DDLLC

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Re: What material to use for a coolant tank?
« Reply #29 on: February 09, 2019, 09:28:00 AM »
Pucker factor then approaches infinity!  :-o :-D :-P
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