Plastic Shipping Container For Hot Water Storage

[WStayton]

I'm contemplating use four each plastic shipping containers for hot water storage for my whole-house system.

  These containers are inside of a metal framework that supports them . . . sort of!  The metal framework is made out of metal that is something like 0.150 or maybe eighth inch (0.125) steel rod that constrains the internal plastic tank.

  These containers are only rated for 120 F, so I contemplate inserting a sheet of 0.250 plywood inside of the metal framework to provide support for the plastic tank which I anticipate having at a temperature higher than 120 F.

  The containers measure, externally, 43 inches wide by 45 inches high by 48 inches long outside of the cage and all supporting structure, and the internal tank dimensions are more like 40" x 42" x 45", for a volume of about 320 gallons if filled full.

  I would use four of these tanks, side by side, with a short length of 1" tube attached between adjacent tanks at approximately the 90% fill point, so there would be about 30 gallons of capacity above the connecting tubes.

  I would use a grid made up of 9 pieces of copper finned baseboard heat tube, each about 43" long, soldered in parralell for a heat exchanger in each container for each of two circuits, one for the engine-generator and one for the roof mounted solar water heaters.

  The fluid to be cooled (automotive antifreeze/water 50/50) in each circuit would enter the first heat exchanger, flow through it, flow out and into the 2nd heat echanger in the second container, then flow out of that heat exchanger and into the 3rd heat exchanger in container 3 and then out of the container and into the 4th heat exchanger in container four and then out of that heat exchanger and back to the engine.  The circuit for the solar water heaters would be similar with four additional heat exchangers, one in each container.

  The wood fired boiler would heat water that would flow into container one directly, with no heat exchanger.  The "filling" of container one would cause it to overflow, via the 1 inch connector, into container two which would then overflow into container three which would then overflow into container four and then it would circulate back to the pump and to the wood fired boiler.

  Similarly, hot water for the baseboard heating in the house would be drawn out of container one and returned to container four allowing the water to run via the interconnecting lines to the other containers.

  Additionaly, domestic water to supply hot water would flow through a copper line through tank four and then through tank three and then through tank two and finally through tank one before it flowed to the domestic hot water outlets such as sinks/baths/washing machine/etc./etc.  There would be a couple of extra loops in each tank for adequate heat transfer.

  With the engine-generator running at 20 kW, I will be producing about 26 horsepower which equals about 66,000 BTU per hour.  I think I will be able to recover, between the engine cooling water and the exhaust manifold cooling water, about 1.5 times this amount of heat, so I should get about 99,000 BTU/hr in round numbers, with another 33,000 BTU/hr lost via exhaust and radiated heat.  Since I have 280 gal/tank x 4 tanks x 8 lbs/gal = 8,960 lbs of water and 1 BTU raise the temp of 1 pound of water 1 degree Farenheit, I should raise the temperature of the total water storage about 11 degrees F per hour.  Since I think I will have to run about 6 hours at a time, I will thus raise the temperature of the tanks by about 66 degrees F.  I expect that I will have about a fifteen degrees per tank temperture differential, so if my hot tank is 210 degrees after six hours, the cool tank will be 165 degrees F.  All of these are above the temperature for which these tanks are rated.

  My specific question is, if I completely support the tanks, using a 0.250 marine plywood inside of the approximately 5" x 5" grid of eighth inch steel support rods, so that the tank reallly has to do nothing except retain the water, and all the support is provided by the steel rods and the plywood, will they (the tanks) stand up to the 210 degree F temperature of the hottest tank???

  I picked these tanks because they are, like me, cheap!  I can aquire them locally for about $100 each.  A 1500 gallon tank, which is slightly more than the four smaller tanks, fabricated from a plastic material having higher thermal capability and rated for 220 degree fluid will coist about $3,000 and four smaller tanks of an equal capacity, of the same high temperature material, will cost more than that.  I would really like to save $2,600, but I don't want to save that much and then have to replace the tanks once a week - especially since I envision foaming them all in place with 12" of closed cell foam for insulation, so digging one, or more, out will be a big time PITA!  <grin>

  My less specific question is:  What's wrong with this set-up?  What could I do that is better and/or would work better/more-efficiently?

  Speak, please!  <smile>

Regardz,

Wane Stayton

[mike90045]

I'd get one tank, frame it up, and apply hot water from the waterheater, and see what happens in a couple hours.  Does it melt to a puddle of goo ?    They came up with the thermal spec for some reason......

[LowGear]

These are neat containers.  So you're looking at 180 degrees.  Have you tried just pouring a quart of boiling hot water on a corner and see how soft it gets?  Is there a sticker that tells what they're actually made of so you can research the compound?  How about contacting the manufacture?

Casey

[Ronmar]

Interesting concept, a drawing might help us to better visualize this complex system, and fully smell what you are laying down:)

As for your prime question, will it work with the temps involved, I don't know.  If you can get them for $100, if it were me, I would buy one, modify it like you described, put some insulation around it and then heat the water inside to see if it will stand up to your intended application...

The first thing I see is that when running the engine, in order to get 210F in that first tank, you first must be feeding it greater than 210F coolant?  IE: heat transfer is from warmer coolant to colder storage tank, and you need a difference to transfer energy.  IMO, I think it would be better to add heat to all tanks in parallel.  I think this would make for more consistent numbers to the engine.  Also you must also plan for when the tanks can no longer accept as much heat as fast as the engine is putting it out, so a radiator on the engine coolant input to dissipate any remaining excess heat the tanks could not absorbe would be a good idea IMO.

Another problem with storing really high temperature fluids is loss.  The higher the temp difference between the tank and it's surroundings, the greater the heat transfer.  IE, it is probably more efficient to store a greater volume of a lesser temp, as it will loose less heat with a reasonable ammount of insulation.  Would 6 tanks be feasible, run at say 160F?  That would put the tank temps much closer to the speced 120F of the tank skin...

The wood fired boiler daisy-chaining across the tanks may be a problem, as the hot water input is less dense and just stays on the top and chains over to the next tank, never transfering all it's heat into the tank.  Before you know it, you have very hot water fed from the last tank back to the boiler input, and it starts making steam to be fed back to the storage tanks... Also you start approaching boiling without proper ventilation, and you have the potential for some pretty serious failures.  I like the mythbusters hot water heater shows as a wonderfull example of why not to approach boiling points in thermal storage:) Again, my reccomendation would be to draw the boiler feed water from the bottom of all 4 tanks simultaneously(coldest water in the system), and return the hot water from the boiler to the top of all 4 tanks simultaneously, with a double redundant thermal shutoff scheme so you don't melt or burst something.  Feeding the coldest water to the boiler will result in the greatest thermal transfer rate, and shorter boiler run times...  

Same goes IMO for the heating loops taken from the tank.  Draw the hot water into the heating loop(thru a tempering valve) from the top of all 4 tanks, and return the cold fluid to the bottom of all 4 tanks.  The tempering valve will determine the ammount of water taken from the tanks to maintain a particular heating loop temp.  So when the tanks are hot, it only uses a little water, and as the tanks cool down, the heating loop uses more and more tank water to maintain the heating loop at a constant temperature...

I guess what I am trying to say, is that in general, treat the 4 tanks as one.  Connect the bottoms together via manifold, and connect the tops together via manifold.  Draw your boiler supply from the bottom(cold) water, and return it's heat to the tank tops.  Draw your heating loop heat from the tank tops(hottest water) and put your solar and engine heat exchangers in the bottom(coldest) part of the tanks so they have the greatest temperature differential/greatest transfer rate...

[mbryner]

I'm skeptical about your tanks getting that hot (200+ F).   I have about 500 gal and with making a fire 2x/day in our masonry stove, the circulating heating loop never gets the tank above 110 F.    That's w/ 8 inches of styrofoam and R-max insulation.   

And, like Ronmar says, you have to have a significant temp differential for heat transfer.   There will be a point where your engine will overheat because the heat transfer can't keep up.

And, if your tanks do get that hot, I always worry about plastic tanks w/ high temps.   Like the others said, check some of the tank material with boiling water first.

Or do what I did and build the darn thing even though people tell you it won't work.   

Marcus

[LowGear]

The common thread I see in this thread so far is "Start with One".

Casey

[mr.fixit]

 Lots of good discussions on hot water storage tanks at http://www.hearth.com/econtent/index.php/forums/viewforum/21/  aka the boiler room. Use the search function.
Personally I used a used 500 gallon propane tank for my boiler storage,closed system. works well.                           Not so sure about the long term stability of the plastic tanks when used at higher temps,they may degrade over time.

[WStayton]

mike90045

  You are exactly right - the only way to know, for sure, is too go get one and try it!!

  I was just hoping that somebody had already done that and I could learn something without going and getting one - they are for sale about 80 miles from me, and strapping my butt to the truck and arcing off to get ONE is exactly the same amount of trouble as going to get FOUR of them.  If I could learn something without driving the 160 miles, roundtrip, I was all for it!  I don't do EVERYTHING the hard way, though it probably seems as though I do!!!  <grin>

LowGear:

  Everything that I have seen has been resellers selling used itams and they tell you exactly jack-squat about the material.  I guess, as mike90045 has suggested, the solution to the problem is to buy one then I can read off of it what the material is and actualy try iut and see if it melts into a pile of goo!  I'm inclined to think that they won't completely melt, since they are most probably thermosetting and not thermoplastic, but I have no way, short of going to where they are available, 80 miles away, to know this.


Ronmar:

  A drawing?!?!?! Perish the thought!  When I was working as an engineer I was always being kidded about my "cartoons" masquerading as engineering drawings.  Also, there was always a pool of people betting on how long it would be, after I presented a drwaing at the machine shop, before a machinest would show up to ask me "What in hell do you REALLY want here, so I can go ahead and make it?" <grin>  My absolute specialty was overdimensioning things, so that they couldn't be built to my drawing!  So, on balance, I think we are better off WITHOUT one of my drawings!

  What I am envisioning is pretty simple conceptually - just a set of tanks in series with a set of heat exchangers, simlarly in series.

  About the 210 final temp of tank one:  The Mercedes uses a 15 psi pressurized cooling system which should give me something like 235 F.  With about 36 feet of finned tubing as a heat eachanger, I think that 210 is ultimately achievable, for a delta T of 25 F across the medium.  I selected finned copper tubing in parallel because that would give me relatively low liquid velocities for a fairly long transit time, and so, lots of heat transfer.  To solve the the heat transfer equations for this case is a lot more effort than I am willing to put into it, so I SWAG'ed it.  Also, I don't know the characteristics of the finned tube completely, so I would have to make a bunch of assumptions and figured that even IF I did the heat transfer equation it was still a SWAG, so I picked the easy way!  <grin>

  I elected for the series configuration instead of a parallell configuration thinking that when there wasn't mush excess heat, such as during the summer and there is enough solar to produce enough electricity to so I don't need to run the generator, and it is warm enough that I won't have the auxilary wood fueled boiler running, but it is still cloudy enough that the solar collectors are not runing at optimum, I would still have enough solar heat to warm one tank and thus supply domestic solar hot water.  I'm NOT a fan of cold shower's!  (But, I think I will probably have an "instant" gas fired water heater in the domestic circuit to ensure that this will, absolutely not happen!)  But, again, I am cheap, so if I can get by without spending money for gas for the water heater, I will try to do it!  <grin>  If all the tanks are in parallell, I will, maybe, only have tepid hot water in the marginal solar wter heater periods.  Also, I think (always dan . . .) that there is more heat transfer if I have four tanks in series and four heat exchangers, likewise, in series, rather than just having what is essentially one big tank and one big heat exchanger which is what I will have if I put them all in parrallel.  Not sure if this is correct, though!

  Since six hours of engine running approaches maxing out my heat storage, you are right that I need some way to discharge excess heat - I hadn't though of this problem!  <grin>  Maybe a modest sized automotive radiator in the engine coolant circuit, after the storage tanks, with a DC cooling fan on the radiator that is set to come on when the incoming coolant is above 165 F?  I can fiddle with the set temp with an adjustable thermostat until I get some setting that works.  Glad I asked, because I hadn't even considered this problem!  Thanx!

  About the loss of heat problem:  I was thinking to insulate with 12 in of closed cell foam which would be something like R-84.  I would do this on the sides and the top, top to be a removable "block" so I can get in the tanks if I have to.  There is about 4" to 5" of space in the metal "pallet" that is part and parcel of the containment cage, so I was thinking to fill this space with foam also, but that would only be R-28 to R-35 on the bottom and the "runners" for the pallet are a direct thermal pathway from the bottom of the wood under the plastic tank to the underlying concrete, they are, however, of a pierced metal construction so the total metal bridging the gap between the wood, which will underlie the plastic containment vessel, and the concrete is something like 32" by 0.125 inches, which I THINK I can live with!

segregating/layeing of hot water problem:  I thought about this problem, too.  One possible solution is to have the connection between the tanks come from the bottom of the hotter tank to the top of the cooler tank.  This way, any time there was flow through the system, it would also mix the water in each tank.   This would add to the thermal isloation of the hottest tank vs a vs the coolest tank, since the coolest water from the hottest tank is what would be transferred to the next tank.

  I was thinking to draw the boiler "cooling" water off of the bottom of the cool tank and discharge it into the top of the warm tank. And likewise, discharge solar heated water into the top of the hottest tank and withdraw it from the bottom of the coolest tank.

  Having seen the result of a large boiler over heating and blowing out on end ot the boiler, and, subsequently, one end of the building that was its home, I am more than a little shy about having large quantities of pressurized hot water around.  However, the only thing in my sytem that won't be at atmospheric pressure is the engine coolant "loop"; everything else will have, at most, a couple of psi generated by the small circulating pumps working against the resistance of the piping.  The tanks themselves will be at exactly atmospheric pressure since there will be a vent on the top of each of them.

  I AM a little nervous about the possibility of one of the interconnecting 1" pipes getting plugged and then having the circulating pump, pump three tanks full of coolant out on the floor and whats worse, into the insulation package.  Closed cell foam isn't SUPPOSED to absorb water, but I'm not absolutely sure that anybody told the foam that!  <smile>  My risk analysis was that it shoudn't be a problem since the connecting pipes were of pretty substantial size and there wasn't really anything floating around in the sytem to plug them up, but I'm thinking at least a quarterly peek and maybe a yearly drain-down and rodding of the connecting pipes is warranted - at least once to confirm that there was nothing accumulating in the pipes.

  On a side issue:  I have been concerned about how to keep something from growing in the tanks.  Since I am going to have a total volume of something like 1160 gallons, that is far and away too much to think about putting permanant antifreeze in, at least in anything like a meaningful percentage with respect to freezing point.  But would a VERY dilute concentration, say 5 gallons in the whole volume, provide enough biocidal action to prevent anything from growing in the "water"?  Or an ongoing gallon-a-week just for Mom and the underwriters?  <grin> Or are there commercial biocidal agents that are manufactured for just such cases/uses?

  Other than the thought's of catastrophe, is there any other reason, Ronmar, that you think I would be better off with a parrallell system instead of a series system?  Again, I think I remember from a heat transfer course, long, long ago (and NOT my favorite subject, even then!) that the heat transfer is increased by having the the sequential set of cascading temperatures vs just having one big tank and one big heat exchanger. 

  Does anybody remember heat transfer better than I do???


mbryner:

  "Or do what I did and build the darn thing even though people tell you it won't work."

   Well, I'm not really interested in doing something just for the exercise (though I could use a little more of that!  <grin>) so that is why I asked before I, fat-dumb-and-happy, did something stupid and had a swimming pool with melted plastic floating in it!

  I've always been more of a "come-let-us-reason-together" type than a "my-way-or-the-highweay" type - that's why I asked.  If I was just going to do it my way, no matter what, I wouldn't have joined up with this loose confederation of "experts" so I could present my case and hear conflicting/contrary opinions.  I don't expect that everybody will agree with me - heck, the world would probably be a boring shade of gray if everybody agreed about everything - but I DO value the ernest exchange of ideas - different from mine or not and I hope that you do too!  <smile>

That's my story and I'm sticking to it!

Regardz,

Wayne Stayton

[LowGear]

Hi Wayne,

Everything that I have seen has been resellers selling used itams

How about contacting the manufacture?

These puppies just might be made in the USofA.

http://www.google.com/#hl=en&sa=X&ei=qmuhttp://www.google.com/#hl=en&sa=X&ei=qmuXTdy2DovSsAPE1rnEBQ&sqi=2&ved=0CBkQBSgA&q=275+gallon+tote+manufacturers&spell=1&bav=on.2,or.r_gc.r_pw.&fp=c99decee79d1fe4a

If you get to the multiple tank process I'd look at getting one of those house insulation people to stop by.  Very low pressure high volume expansion.

Casey

[rcavictim]

I have three of those transportable tanks.  I have heard them referred to as a 'Tote'.  They might be medium/high density polyethylene.

[Ronmar]

 What I am envisioning is pretty simple conceptually - just a set of tanks in series with a set of heat exchangers, simlarly in series.

that might be ok ifyou were circulating the water 100% of the time to keep it intermixed.  But you also mentioned connecting the tops together?  That is not 4 tanks in series by my definition...  what you have is 4 large boxes of water with relitively small movement in the tanks.  add energy, and these tanks WILL stratify.  This is not a bad thing.  Hot is on the top, and cold is on the bottom.  You can use this to your advantage.  I know I am planning to:)

About the 210 final temp of tank one:  The Mercedes uses a 15 psi pressurized cooling system which should give me something like 235 F.  With about 36 feet of finned tubing as a heat eachanger, I think that 210 is ultimately achievable, for a delta T of 25 F across the medium.  I selected finned copper tubing in parallel because that would give me relatively low liquid velocities for a fairly long transit time, and so, lots of heat transfer.  To solve the the heat transfer equations for this case is a lot more effort than I am willing to put into it, so I SWAG'ed it.  Also, I don't know the characteristics of the finned tube completely, so I would have to make a bunch of assumptions and figured that even IF I did the heat transfer equation it was still a SWAG, so I picked the easy way!

The problem with the finned tube is it will build up laminar flow, and the water flowing along the inner skin of that smooth tube will give up it's heat then act like water in a wetsuit and provide insulation between the hot core current and the outer skin... One thing that will help is to add some bare strands of copper wire inside the tubes to disrupt the flow and force the hot center current out aginst the tube walls where it can give up it's heat.

 I elected for the series configuration instead of a parallell configuration thinking that when there wasn't mush excess heat, such as during the summer and there is enough solar to produce enough electricity to so I don't need to run the generator, and it is warm enough that I won't have the auxilary wood fueled boiler running, but it is still cloudy enough that the solar collectors are not runing at optimum, I would still have enough solar heat to warm one tank and thus supply domestic solar hot water.  I'm NOT a fan of cold shower's!  (But, I think I will probably have an "instant" gas fired water heater in the domestic circuit to ensure that this will, absolutely not happen!)  But, again, I am cheap, so if I can get by without spending money for gas for the water heater, I will try to do it!  <grin>  If all the tanks are in parallell, I will, maybe, only have tepid hot water in the marginal solar wter heater periods.  Also, I think (always dan . . .) that there is more heat transfer if I have four tanks in series and four heat exchangers, likewise, in series, rather than just having what is essentially one big tank and one big heat exchanger which is what I will have if I put them all in parrallel.  Not sure if this is correct, though!

Again, if you are chaining the tops of the tanks together, that is not series is it?  What will keep that heat from spreading to the tops of the other tanks?

segregating/layeing of hot water problem:  I thought about this problem, too.  One possible solution is to have the connection between the tanks come from the bottom of the hotter tank to the top of the cooler tank.  This way, any time there was flow through the system, it would also mix the water in each tank.   This would add to the thermal isloation of the hottest tank vs a vs the coolest tank, since the coolest water from the hottest tank is what would be transferred to the next tank.

I don't consider it a problem.  In fact, I consider it a benefit, as it helps me concentrate heat in a particular area ready for transfer to somewhere else.  So do you want a stratified tank with hot water readilly harvestable at the top, or 4 tanks of mixed lukewarm water?

 I was thinking to draw the boiler "cooling" water off of the bottom of the cool tank and discharge it into the top of the warm tank. And likewise, discharge solar heated water into the top of the hottest tank and withdraw it from the bottom of the coolest tank.

That is good for the last tank, as if the tops of the tanks are chained together, the heat again will just flow across the tops of the first tanks and only be drawn downward in the last tank that has outflow from the bottom...

 Other than the thought's of catastrophe, is there any other reason, Ronmar, that you think I would be better off with a parrallell system instead of a series system?  Again, I think I remember from a heat transfer course, long, long ago (and NOT my favorite subject, even then!) that the heat transfer is increased by having the the sequential set of cascading temperatures vs just having one big tank and one big heat exchanger.

I would say it would depend on the tank and heat exchanger.  Your best thermal transfer coms from opposing flows/temperatures.  IE: The hottest primary input flow meets the hottest secondary output flow, and as the two fluids exchange heat, they maintain a constant delta across the entire heatexchanger.  In a tank, one of your flows is going to be convection, so you need to size the heatexchangers to be large enough to deal with the slow secondary flow and transfer the heat in an acceptable ammount of time.

How are you planning on getting these heatexchangers into these tanks anyway?

I have a drawing I did for someone else, let me tweek it a lttle and I will upload it so we can pick it apart:)

[Bottleveg]

This may help-
http://en.wikipedia.org/wiki/Intermediate_bulk_container

[WStayton]

Okay, I just spent three hours pecking away at a response and had some sort of stupid attack and dumped it into the ether!!!

This will be the re-hash, thrifted since I'm gettng tired of hunting and pecking away!  <grin>

In the order in which they came in:

LowGear:

  Don't know if its me, my machine, or the link you posted, but all I get is the Google screen with a box to input your search criteria.  Don't know enough HTML to figure out if there is something wrong with your link or if its me,  so I'm kind stuck!  Thanx for the link - wish I could tell what it is to! <grin>

rcavictim:

  The computer Gods definately like you more than me - when I google "tote" all I get are lots of sights that have something like my grandma used to take out to the garden and come back with it full!!!  <grin>  I guess I just have to look further than two pages into the 48,00 returns I get for "tote".   Or, maybe, the damned machine just doesn't like my torture!  <smile>

  I did try "tote" with "shipping container" and get a few things that looked like what I was talking about, so you are right, that name is especially important to identify this object in question to the 'net!  Thanx!

Ronmar:

  I am thinking that I miscommunicated here - I envisioned connecting the bottom of the warmer tank to the top of the next cooler tank - so:  bottom of tank 1 to top of tank 2, bottom of tank two to the top of tank three, bottom of tank three to the top of tank four.  I THINK ( always dangerous, . .. yada. yada, yada) that this is in SERIES, not parallell, no?  Wouldn't I have to come out of the furnace heating loop into a "splitter" and then into all four tanks, then out of the tanks into a "joiner" and then back to the stove, to have them all in parallell?  Yes?

  Incoming hot water would all go to the top of tank one.  Outgoing, hopefully cooler, water would come out of the bottom of tank four.

  I made one FUBAR in my original description - the engine already has its own heat exchanger in the "box" that also has the cooling for the exhaust manifold, so this loop would also dump into tank one and the cool water back to the engine would come from the bottom of box four, eliminating four heat exchangers.

  The solar heat exchangers would, however, have to have their own set of four heat exchangers since I have to run antifreeze in that circuit to keep the solar heating panels from freezing, up on the roof.

  About the wire in the heat exchangers - it seems to me that I vaguely remember reading a paper by a Japanese researcher, once upon a time, on exactly that subject.  Something about the shape of the wire is as important as having it there - if I remember correctly, a wire diamiter of something like 1/50 of the diameter of the tube it was running in, and bending it in a spiral of about 3/4 of the diameter of the containment tube vastly improved its performance.  I'll have to go look for the paper, but it seems like a coil fabricated of the right size wire, in the right diameter coil with the right coil "pitch" something like doubled + the heat transfer of the tube compared to a bare tube.  Thanx for that input - I NEVER would have remembered ANYTHING about it if you hadn't reminded me!  Now I have got to go and find that paper!  <grin>  Thanx!  You don't, by any chance know who the author of the paper was, do you?  <hope> <hope> <hope>

About heat exchanger insertion:  Since the hole in the top of the tank is something like 10" diameter, they heat exchanger will have to be assembled in the tank, I think.  I was thinking to fabricate a manifold of 1.5" tubing having nine 3/4" holes along its side then braze a very short piece of 3/4'' tube into each of the holes.  The finned tubing lengths of 45" + / - ( as long as possible) would then be toined to the stubs with a compression union.  The heat exchanger length in hole # 1 on the inlet manifold would be joined to tube #9 of the outlet manifold, thus they would all have the same resistance to flow and the flow through all of them would be even.  It would be a PITA to fabricate this all while reaching through a 10" diameter hole, but I don't really see an alternative.

ANY drawing that you would care to produce would be vastly superior to anything I would concoct and so is heartily solicited!  <grin>

Jens:

  I HAVE to go get one of these containers - because the ONE that I remember seeing close-up, maybe ten years ago, I THINK had a wire up each corner and you could just pull it out and the whole thing would collapse so that it didn't take up so much room when shipping empty.  My inspection was less than comprehensive, so I don't really recall, if I ever knew, how stiff the plastic interior container was, but, if the "box" folded up, I would think that the inner container would also be somewhat flexible.

  My thought was to take the plastic container completely out of the containment vessel, add the 1/4" marine plywood sides - sealed and painted - with a piece of cove molding to elminate the sharp corner, everyplace that ply met ply, and then re-insert the plastic liner.  If I CAN do this, the net stress on the inner plastic container would have to be almost nil, since everything is suported.  The pressure is pretty modest - less than 2 psi max, so I don't think much of a membrane is required to keep that from leaking as long as the 1/4 " plywood lining supports everything else.  But, until I get my butt in gear and go get one and see if 1) I can indeed insert a plywood lining and 2) The lining DOES support everything so that the temperature doesn't cause a blow-out, it is all moot!

I see a drive in my future!  <grin>

See above about the exhaust-manifold/heat-exchanger, container-sequencing, etc., etc. . . .Engine won't be fed cold water since it will have its own supply of circulating coolant/antifreeze.

About it getting a little complex . . . the whole matter is clearly a large exercise in cutting the leg off of two hundred chairs and expecting them to all be level!!  I am sure that it will take more than a little tweaking - I'm just hoping that I have no major redesigns!  <girn>  Does anybody sell insurance on projects like this?  Yea, I know, the price of the policy is the value of everything involved plus the cost of the labor involved plus adjusting costs! <smile>

Bottleveg:

   That's it, exactly!  Too bad they don't tell you more about what it is made out of. . . You did find a picture, though, I wasn't able to do THAT!  Thanx.

Thnak-you, everybody, for you're input - it seems crystal clear that I need to go get one of the containers and determine experimentally, whether or not it will work.  In the last analysis, there is NO substitute for having your hands on the item in question.

Regardz,

Wayne Stayton

[Ronmar]

I have never heard of a paper discussing the turbulator wire design, but I would also be interested in reading it if you come across it:). I came across it in reference to home brewers trying to make their Wort chillers more efficient, and adding a twisted wire inside the tubes really helped.

[WStayton]

Ronmar:

  Paper about inserts in heat exchangers:  As I recall, it was an SAE (Society of Automotive Engineers) from some time back when I was still working for Ford - So that would make it in 1985, or sometime in the previous 14 years.  I guess I can google SAE papers and maybe find it that way.  All the SAE papers were circulated among the Ford Engineers when they came out, through company mail - that's how it found it's way to my desk and I just sort of casually flipped through it - never dreaming that it was something that I would REALLY be interested in 30 years later!  I'll let you know when/if I find it.

Jens points out that something like this is used in gas fired hot water heaters, but I THINK (yada, yada, . . .) that the hot water design is more of an elongated metal "tab" the is bent into a spiral to give better heat transfer characteristice to the hot exhaust stream.

Jens:

  Building a tank:  I looked at building a tank when I originally looked at the project.  I was thinking of a simple rectangular tank of 4' wide by 12' long by 6' deep, for a capacity of 2200 gallons or so.  My back of the envelope of cost quickly ran to more than $2,500 by the time I got it framed with something heavy enough to keep the whole thing from spreading apart, and prop it up off of the floow so that I could see under and, hopefully, identify leaks and their location before they had catastrophic consquences. This would be  then sheathed with marine plywod that wouldn't come apart when it got wet, and then linined with sheet metal to contain the liquid.  This included 12" of closed cell foam on six sides, whiich ain't cheap, but I'll have to buy some of that for the tote tank design, too.  Also, I couldn't figure out anyway to fasten the corners together on my sheet metal tank that wasn't going to be a pain, since my sheet metal welding skills are ZERO!  I also looked, briefly, at fabricating an epoxy resin fiberglass reinforced tank/liner but that was yet still, more money. In the end, I decided to let somebody who already knew how to make tanks, do that job, and not learn a whole new set of skills that I would only use once and in which I am not very interested, anyway!  <grin>

About the opening sides:  I was talking to my brother about this issue - since it was a tank that he had purchased full of molasses for inclusion in cattle feed, that I had remembered seeing.  He says, that when he was getting one of these a month, full of molasses, back ten years ago, that practically every one of them was different and as far as he remembers, the one's with the "zippers" in the corner were in the minority by a factor of at least ten.  He, too, said "The only way you're ever going to know if it works is to get one, insert the plywood sides, if, indeed you can, and then fill it up and  put a heater in it and see what happens."  He also suggested not doing it anywhere that water would be a problem! He also pointed out that I should leave it heated for at least thirty - better sixty or ninety -  days before I pronounce the experiment a success since plastic creeps slowly, it might work initially but leak like a seive after a period of time. <grin>

About going insane while assembling heat exchanger's inside of totes:  Most folks think that I am ALREADY insane, so what can a little aggrevation add to that?  <smile>  I agree that it will be a colossal PITA, but I think the additional heat transfer capability of the finned tubing, over a simple, easy to insert, copper tubing coil is worth the aggrevation.  There are 72 compression unions to put on on 36 lengths of finned tubing and if it takes me 30 minutes per union, that's a week of work.  I'm retired and I HAVE the time and I am willing to put it in, if necessary.  If my posts turn to gibberish (worse than they are already!!) you will know that it didn't work-out so well!  <grin>

About the engine cooling "loop":  The engine has its own, self contained cooling loop that uses the heat exchanger in the exhaust-manifold/heat-exchanger assembly to extract heat from the engine coolant.  I don't think that this can be 100% efficient - by a long shot - so the engine coolant returning from the heat exchanger must be at least warm - especialy since the water from my storage system that I am running through the heat-exchanger will only be as cool as the bottom of the coolest tank.  Also, Mercedes is fussy about details, and I don't think that they would sell engines to Nanni, to go out into the world with the Mercedes nameplate on them, that cooled in a way that would cause them to have a short service life.  Also, this means of cooling is used in lots of marine diesel engines, so I think it MUST work, otherwise somebody would have done something else.  I have done zero poking arond into the heat transfer of the internals of the Nanni heat exchanger, but they are still in business, making a very similar unit, installing it on a VW Motori four cylinder diesel that is very like the Mercedes (though I'm sure it is also about 50% of the first cost of the Mercedes) and, as far as I have been able to determine, they have had no cooling problems with these, or with the predecessor Mercedes, units.  I am not usualy one to take somebody's else's word for anything (You may have noticed! <grin>), but in this case, I think acceptance of their design IS warranted without any redesign on my part.

That's my story and I'm sticking to it! <smile>

Thanks for the input, guys!

Regardz,

Wayne Stayton