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
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......
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
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...
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
The common thread I see in this thread so far is "Start with One".
Casey
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.
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
Hi Wayne,
QuoteEverything that I have seen has been resellers selling used itams
QuoteHow 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 (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
I have three of those transportable tanks. I have heard them referred to as a 'Tote'. They might be medium/high density polyethylene.
Quote from: WStayton on April 02, 2011, 11:15:03 AM
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:)
Quote from: WStayton on April 02, 2011, 11:15:03 AM
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.
Quote from: WStayton on April 02, 2011, 11:15:03 AM
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?
Quote from: WStayton on April 02, 2011, 11:15:03 AM
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?
Quote from: WStayton on April 02, 2011, 11:15:03 AM
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...
Quote from: WStayton on April 02, 2011, 11:15:03 AM
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:)
This may help-
http://en.wikipedia.org/wiki/Intermediate_bulk_container
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
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.
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
EDPM sheet is what you're thinking of.
Have you considered using good condition 200 gallon oval steel home heating oil tanks? You should be able to acquire these with a bit of searching for in the ballpark of $50 each.
All EDPM is not created equal. I've seen it used for roofing and for water features. Not the same stuff exactly.
But let us return to the original question. 275 gallon totes and their ability to store hot / warm stuff?
They sell for around $100+ in the Seattle area in nice shape.
How hot is hot?
How many BTUs are in a gallon one degree above ambient?
How many degrees above 70 (a nice room temperature) do you have to be in order to harvest heat from your stored water?
Isn't a floor heated to 120 degrees pretty warm? (What was the label warning about temperature?)
Do you need to consider that one of these puppies weigh (275*7.5=2,062) or a clean ton?
Can we get the water cold for use during the summer?
Casey
A 4x4x8 box of water weighs just under four tons...
and stores the energy of 6-1/2 gallons of gasoline (787400 BTU) if you raise the temperature 100 degrees from a 55°F ground-water temperature.
I think that much water needs more than 2x6 framing.
The thing to keep in mind (I think therefore I make mistakes) is that it takes no more strength to hold back four foot of sea than four feet of bathtub. That comes to less than 2 psi at the bottom foot and something like .43 for the top foot. You have seen how flimsy above ground pools are and they have no top straps. There are far better trained minds than mine that can explain this phenomena.
6.5 gallons of gasoline. 100 degrees? Nearly 1000 gallons of water. This is starting to sound feasible. So to raise one of the totes (slightly more than 1/4th the volume) to 140 degrees is looking like 1.5 gallons of gasoline or less? How many BTUs in water heat does his engine put out? Capture-able exhaust heat?
So back to the basic questions:
Quote
How many BTUs are in a gallon one degree above ambient?
How many degrees above 70 (a nice room temperature) do you have to be in order to harvest heat from your stored water?
Isn't a floor heated to 120 degrees pretty warm? (What was the label warning about temperature?)
Do you need to consider that one of these puppies weigh (275*7.5=2,062) or a clean ton?
Can we get the water cold for use during the summer?
Casey
Quote from: LowGear on April 04, 2011, 06:36:20 PM
So back to the basic questions:
How many BTUs are in a gallon one degree above ambient?
That depends on what your starting point or ending point is... 1 BTU will raise 1 pound of water 1 degree F. So to get that 1 gallon of water to warm 1F above it's starting point(ambient temp?), you expended 8 BTUs...
Quote from: LowGear on April 04, 2011, 06:36:20 PM
How many degrees above 70 (a nice room temperature) do you have to be in order to harvest heat from your stored water?
It depends on your heat transfer method and time available. heat transfer is mainly about temp difference, flow rates and time. A large heatex needs less time and heat difference to move a given ammount of heat than a smaller heatex. In-floor radiant heating for example has a large surface area, so uses a much lower transfer temp, perhaps 90F or even less depending on other structural factors such as sealing and insulation. Small baseboard heaters have less surface area, so need greater temps to heat air, say in the 110+ degree range
Quote from: LowGear on April 04, 2011, 06:36:20 PM
Isn't a floor heated to 120 degrees pretty warm? (What was the label warning about temperature?)
from what I have studied, 120 would be way too hot to feed a radiant floor... You use a tempering valve to mix hot source water with returning cool water to maintain as constant a floor loop temp as possible...
Quote from: LowGear on April 04, 2011, 06:36:20 PM
Do you need to consider that one of these puppies weigh (275*7.5=2,062) or a clean ton?
water is heavy:)
Quote from: LowGear on April 04, 2011, 06:36:20 PM
Can we get the water cold for use during the summer?
cooling is a whole nother can of worms with it's own engineering challenges.
Wayne
As for the tank, your best bet for integrity is to go round. the 1500 gallon above ground pool I set up each year has no 2X4's or heavy plywood... it just has a continous band spreading the outward force evenly to the other side. I will be building my own tank also and it will be round as that is the easiest structure for me to make self supporting. you also need to consider the weight per square foot. What sort of structure is this much water going to be setting in/on?
Jens alluded to one of the issues you will run into with the engine feeding the tanks. it is going to cycle as it gulps cold coolant. The problem this makes, particularly with series tanks is it will be circulating cold water right on top of the hot water in the tank, with the engine burping pockets of hot water in there as it cycles. You will end up with the heat spread out throughout the tanks, instead of heating the first tank first, then working on down the line. What you need is a thermostat in the secondary loop to only let out a desired temp of water. IT, no flow till the water gets warm, or only warm water leaves the engine heatex. This is what I do on mine and it works very well. It only outputs 120F water from the engine heatex(engine runs at 195F).
Jens:
Do you think that a box constructed out of 2"x4"'s which is 12' long by 4' wide by 6' deep will be structurally sound? I was afraid that the top would slowly spread apart until something finnaly gave and dumped the whole 2200 gallons of 180 F water in the middle of the space filled with a generator, an inverter, a bunch of batteries and lots of 120/240 AC running around - making the ORIGINAL vert big mess!!! I thought of putting 3/8" threaded rods across every four feet or so, to contain this spreading but, since these are going to be in a hot wet environments, they would need to be stainless adding still more cost. My plan that I thought might (!) work was to build it out of 2"x6" studs on 16" centers with 15/32" Plywood on the inside and have every fourth side stud stick up six inches above the tank and then run a 2"x4" across it to contain the spread. But, if I build it out of 2'X6" and 15/32" ply, and make it waterproof I have already got more money in it than the $100 per 320 gallon tank the other way.
One other point - after some reflection, I thought that it was better to have several containers, in series, so that I could be assured of having enough 150F water to heat domestic hot water, etc., etc. - If I have 2200 gallons of 85F water, I have kind-of missed the temperature boat. I'm trying to design something that works for when I have lots of waste heat AND for when I only have a little. If I create something that only serves one end of the spectrum, I have missed the boat!!
About insulation: I have noticed that some closed cell foam, especially the environmentally friendly stuff that is made out of soybeans, etc., has a max operating temperature of 180F. I have also noted some petroleum based foams are okay up to 250F. Note sure what happens if you insulate your attic in Phoenix with the soybean stuff . . . well, actually, it probably melts and makes a mess! <grin>
rcavictim:
I thought about the steel tanks, usualy ex-fuel oil tanks, around here. One problem: If assembling a heat exchanger is a PITA through a 10" hole, it is REALLY a PITA through a 3" diameter fill-port. With steel tanks I would either have to 1) Take a gas hatchet and cut the end out of the tank, or at least a BIG access hole through it or 2) scrap the idea of assembling heat exchanger's from domestic heating finned tubes and just use smooth copper formed into a circle. I figured it would take a LOT of smooth tube to equal the heat transfer of a finnned tube! Not undoable, but I think that the cost of four or five times as much smooth tube as finned tube, which I figure to get used finned tube pretty reasonably, would be a not insignificant item for a tight-wad like me! <grin> Also, the fuel tanks wouldn't let me lay a whole array of finned tubes side-by-side. Not sure how much they will stratify, temperature wise, and thus I would, maybe, have some finned tubes 30F warmer/cooler than the one on the other side of the array. The possible problems overrode my cheapness, in this case!
LowGear:
"How many BTUs are in a gallon one degree above ambient" 1 gallon = 8 pounds = 8 BTU per degree F for pure water - adding antifreeze degrades the capacity by 20'ish %, for a 50:50 mix. Since I would use pretty much straight water in the holding tank, and I'm thinking to use the 320 gallon ones filled to 300 gallons, so I've got 2400 BTU per degree per tank.
"Isn't a floor heated to 120 degrees pretty warm? " I think that 110 is recommended to unde floor just so that uyou don't burn your tootsies. I was thinking to use baseboard heater's with the same finned tubing in them that I was talking about for a heat exchanger. Baseboards are more accepting of higher temps, though 180F water does make them creak and groan when the water is first turned on and they grow thermally and creak across all the metal suports. Silicone spray lube helps, but still doesn't cure the creaking from very hot water. I CAN live witha fedw creaks and groans, however! <grin>
Weight: They (300 gal) are 2450 pounds +/-, counting the container. My slab is 5" concrete with one layer reinforcing mesh in the middle of it. I would be happier if it had some rebar in it, but it was poured before I arrived on the scene, and, in its previous life, it wasn't really expected to take much of any load since the space doesn't have a door big enough for a vehicle and was built by an amish guy who doesn't/didn't have a vehicle, anyhow! My SWAG is that it will probably crack a little, but since my load is a one time thing, not repetative, the cracks will probably be okay.
"Can we get the water cold for use during the summer?" Um, this is upstate NY - it hits 90 about three days a summer and I'm VERY coldblooded, so I'm not planning on any AC, at all! If it gets hot, I'll just open the window and if it gets into the 90's, I'll use a box fan, that's it! <grin> It only take about three ice cubes for my martini and I like my scotch neat, so I don't see having a big cold storage reservoir! <grin>
DanG:
"I think that much water needs more than 2x6 framing."
Actually, I think 2'x6" is enough if you solve the spreading apart problem, but I would rather have several smaller containers anyway, so it kind of a moot point.
LowGear:
"So to raise one of the totes (slightly more than 1/4th the volume) to 140 degrees is looking like 1.5 gallons of gasoline or less?" Gasoline??? Huh? I'm planning on a diesel - the only gas will be in a can in the corner for the lawn mower and maybe to mix with the WVO for viscosity control! <smile>
" How many BTUs in water heat does his engine put out? " I figured that the engine would be at a 20 kW average overall. A diesel engine rejects about twice as much heat as it turns into work - figure an amount equal to the work in the cooling water and a similar amount in the lube oil and exhaust. I'l be able to recover all of the cooling heat and about half of the exhaust-heat/lube-oil heat becuase I have to leave engough heat in the exhaust that it doesn't condense any where in the system - also, my marine wet exhaust probably isn't all that efficient since their objective was to make the exhaust system cool enough that it didn't catch anything on fire not to extract every last BTU of heat. So, I've got about 30 kW's of heat to use as I see fit. 1 kW-hr = 3414.4 BTU, so I have about 100,000 BTU per hour to play with. For my six hour run time, I will have 600,000 BTU - so my four each 300 gallon tanks, with 1200 lb of water, will increase about 60F.
In summary - I'm pretty convinced that I should use several small tanks instead of one large tank in order to ensure that I have at least some water with useable heat when I only have solar heated water as the source and have a couple of cloudy days.
I WILL get a tank (though probably not in the next two or three days! <grin?) so that I can see if 1) I can, indeed, insert the 1/4" liner and 2) after heating for at least 30 days it doesn't spring a leak or three. If I can't put in a liner, or, if it leaks, I will have to go to something like a metal tank like rcavistim suggested.
I'm pretty comfortable with the amount of heat storage that I will have, since, in the winter, I will have a pretty reasonable heat load - the domestic for a 30' x 40' building with R-11 in the walls and something like R-22 in the ceiling. I probably will increase the ceiling R-value but even with R-22 the heat flow should be manageable. And, I will be able to have as much additional through wood fired boiler, as I want.
Remember, I'm only planning on running the engine for two six hour sessions a week, in the winter, once a week in the spring and autumn and not at all in the summer.
Of course, EVERYTHING is subject to change when, after I get it installed, I discover that I need more or less electricity than the solar electric panels are delivering - the solar electric panels are what really drives everything electric, with the generator just doing pick-up duty for the solar electric panels when they can't handle the load. If I find that I need more solar panels in the long day times, there is room and I will do that, which would also increase the electricity in the winter, but I can't imagine a system that just meets my needs in the long day periods, would be able to meet it in the winter. I will have some significant electrical loads in the winter that won't be there in the summer - namely running the circulator for the dwelling baseboard heating.
For heat, the heirarchy is First) Heat from solar panels, Second) Waste heat from the generator and Third) Heat from the wood burning boiler.
My SWAG is that in the short days of winter, the solar will meet the domestic hot water needs ONLY - domestic heating will have to come from the diesel and the wood boiler. I think that the diesel waste heat will be enough for domestic heat on the days that it is running and the wood fired boiler will have to cover the other five days a week.
The diesel thould burn about a two gallons an hour at 20 kW output - so if it also cover the domestic heating load, I will be heating with twelve gallons a day - fuel oil burned in a furnace is about 140,000 BTU per gallon - so if I burned twelve gallons per day in a furnace, could I heat the 1,200 sq ft dwelling?
I'm planning for a wood burning stove in the living room, BTW - so at least one spot in the place will be warm! <grin>
Thanx, everybody, for the input!
Regardz,
Wayne Stayton
here is a link to the TANK part of the Solar Shed. http://www.builditsolar.com/Projects/SpaceHeating/SolarShed/Tank/Tank.htm
A pretty good article, worth the read for the whole thing.
"decided on a plywood tank with an EPDM liner. These tanks have been successfully used for quite a while, and are reported to have a life of 10 to 20 years and more. They can be built to fit the space you have available. The tanks are easy to build, but the tanks must be structurally up to withstanding the fairly large loads from the water -- 500 gallons weighs 4150 lbs."
I've been collecting pieces for a solar DHW tank for a while and am interested in your project. I'd not be worried about the 'catastropic' failure, it'd be watching the slow-motion train wreck of a wooden tank relaxing over time that would kill my buzz. The 100-year-old Minnesota cellar here is too damp for plywood. Just having the tank down there un-insulated would make this house much happier, it averaged 52°F all winter and has now just warmed up to 57°F. Makes 1st floors floor cold and I hate cold floors.
300 gallons of hot water in a wire cage sounds like a recipe to have tote plastic look like magnum sized bubble-wrap after a heating season. Adding slats between the rods and wrap-insulating the outside sound do-able, beware the thermal expansion heave & shrink of the plastic where any bulkhead fittings go through, a little loose so it can move might dodge some grief.
mike90045:
Would you please make your posts in 24 point type from now on, so the big dummy (ME!! <grin>) will see them right away and notice them. While the rest of us have sort of run around looking at the pennies and nickels dropped on the ground you have, again, hit upon the $1,000 bill!!!! I had previously read some of Solar Gary's stuuf, but either had forgotten that he had a tank, etc. in his system, or completely missed it on my way by.
I had not thought, at all, about EPDM liner material - not sure why - just negligence, I guess. That does, indeed, look like the correct way to line the tank(s) - no problems with temperature capability and I hadn't realized that these were fabricated by lapping the uncut corners up to form a "pleat' and thus eliminate any possibility of having a leaky seam.
Although Solar Gary doen't specifically refeernce any thing like it, aren't there some special fittings for installation through a wall lined with the EDPM material that have big bases with a seal to eliminate/reduce leaking problems?
Disregard all previous references to "storage totes" those ideas are hereby relegated to the scrap heap!
Thanx for pulling my head out of my A$$, AGAIN, mike90045!!!
Jens:
About size of container vs a vs structural integrity: I'm thinking that if I built the tanks out of 1 and 1/2 a sheet width, for height, and made them on 4'x4', L X W, with 1.5"x1.5" around the bottom exterior edge, instead of 1.5"x3.5". I would have 450 gallons each with a fill depth 5.5', leaving room for interconnections that don't go through "under water" and thus reduce the leak chance, and used 1" of polyisocyanurate on the inside, to cover up screws heads, etc., etc, for liner "health". I was planning on my "containers" being insulated by 12" of R-7 foam, and I see no reason to do anything different with these boxes. The only change that I really envision making, besides slightly altering the dimensions, is to make the "encircling" mechanism out of laminated 1"x4" stock, alternating the corner laps, thus making the weakest part of the "encirclement" a bit stronger and a bit easier on the eyes. (Who said that engineers make everything with a chainsaw, and ugly? <grin>) I'm not sure if it should have a vertical "stud" up the middle of each side or not, but it is far easier to put one in and not need it that to build it without one and, later, have a "flood". I would use a 3/4" ply "scab" of 8" x 3/4" marine ply over the joint between the bottom 48" width and the top 24" width of the side material.
Another thing I see that I would do differently is seal and paint with good, oil based, exterior grade paint. Not sure why Solar Gary didn't do that with his, since it isn't a lot of money for a great deal of water proofing and, again, its a little easier on the eyes!!!
I'm not sure if I am wild about that 4' square "box" being unsupported in the middle of the box, though in Solar Garys design I suppose he could have cut the underlying foam to fit in it and not shown that.
"I would suggest at least three tanks in your system - one small tank, an 80 gallon steel hot water tank for example, and then two large 4*8*4 tanks." If I use four 4x4x6 tanks built as above and make one end of the daisy chain hot, shading the temperature to the other end, do you still think I need the small, 80 gallon tank for "HOT" water. I'm thinking that the first tank would be hot enough, even when only getting solar heating to have a reserve for three or four days of cloudy weather. If I have 450 gallons of water, I will have 2700 BTU per degree stored in there - which means that I could draw 3,600 pounds of hot water, warming it 50 degrees and still only have to draw the temperature of the first container down by 50F. So if it was at 180F before my "cloudy" period, it would still be at 130 at the end of it. Why the little tank?
About the temp of the hot water finned tube domestic heating: I only suggest that 180F will work, since that is what my dad had in the house that he built in about 1958. The oil fired boiler came with a large package that contained the tempering valve that mixed the recirculated water with reheated water to give you whatever temp of circulating water you selected. My dad looked at the box full of various valves and sensors and only saw yet another way for something to screw up, so he installed the system without the tempering valve AT ALL. It worked just fine, but, as elucidated previously, cracked, snapped and popped on start up due to thermal growth over all of the supports. My mother b!#$%@d and moaned about the noise, so he siliconed everything, several times, but that only attenuated the noise, it certainly didn't eliminate it, though it eliminate the noise from my mother!!! <grin>
I intend to pull the "hot" water for domestic baseboard heating off of the bottom of the coolest tank - at least until experience demonstrates that that won't work! <smile>
"I am almost willing to bet that you are not going to see that " What do you doubt? The amount of heat rejected by the engine? How much of the waste heat will be absorbed by the water storage bank? Some other part of the analysis? Please elucidate - If I screwed something up, I would much prefer to know about it now, rather than after it is built and trying to operate? I'm expecting to make mistakes - the last guy that didn't make any mistakes, wound up with his feet nailed together, and I'm not, it goes without saying, in that league! I'm hoping that if you see something that you think is "hinky" you will wave a red flag and scream!!! I'm a little slow, to grasp the whole meaning, but if you scream loud enough and long enough, I WILL come around! <grin> So, speak, PLEASE!
Thanx for the input, guys and mike90045, especially - once more I, and my bank account, have been led back from the precapice(sp?)! <smile>
Regardz,
Wayne Stayton
I don't know how they'll be affected by heat but bulkhead fittings are commonly used at depths greater than 4'
http://tinyurl.com/3mrsz6q
Thanks, Geno
Jens:
About holes in the liner:
My thouight was to only fill the tank to within 6" of its top, and then make the connection through the middle of this six inches, so the centerline of the hole would be 3.0 in above the liquid level - but, AGAIN, I think I am inventing a $500 solution to a $5 problem!
I was thinking about how to close the tank with a lid, which fit tightly, without having it interfere with tubes/pipes coming out of one tank and going into another one. A much better solution would be to make the adjoining sides 1.0" to 1.5" shorter than the other sides and just come up and over the 4.5" to 5" of tank side that is above the liquid level. I am a little wooried about being dependent on siphon action to accomplish all of the fluid travel, since if enough air gets trapped in the "loop" over the adjoining sides, it won't siphone anymore, but where is the air going to come form, anyway? I guess the worst case is that a little air will be in solution and come out of solution in the tube and then rise to the top of the loop as a bubble, but if that bubble is smaller than something like 20% - 30% (? - worst case?) of the volume of the loop exposed above the fluid level, it will simply be swept away by the next fluid flow through the loop. Not MUCH air is going to come out of solution, since I don't have an aerator in any loop, anywhere, and every loop discharges under the surface of the water, so, relatively soon, most of the dissolved air will escape and thier won't be any significant bubbles in the loops. The one hitch may be when the fluid sits quiessent (sp?) for the whole summer, with all the fluid flow coming from/through heat exchangers and the bubles can collect for four or five months, but even then, I don't THINK that they will be big, problem causing bubbles.
About joining sheets: If I do it with an 8" wide, 3/4" thick, "scab" that is glued with resourcinol, the joint will be stronger than the material it is made from, so if the sheet of 3/4" marine plywood is not in danger of breaking open, the joint should, likewise, not be in danger. I was thinking that screwing the joint together so that is adequately "clamped" while the resourcinol cures will be a little tricky, in that I don't want to have screws sticking out to potentially pierce the liner material, but if I use 1.25" screws and insert them from the inside of the tank and put the 1" of foam inside that Solar Gary recommends, I shouldn't THINK that I will have a problem. Of course cutting out the 3/4" x 8" slot in the uprignt suports, to go over the "scab", will be a PITA, but, in the scheme of things, it will be a lot less PITA than assembling 36 pieces of finned tubing through a 10" access hole! <grin> Just put the dado blade set in the table saw and keep-on cutting!
About having the 2"x4" bottom cleats on edge rather than on their sides:
Again, I am planning to glue them with resourcinol, so the joints should be stronger than the wood. For construction pine the strength is something like 6400 psi to the elastic limit. At the bottom I will have 5.5 feet depth x .433 lbs/ft = 2.3815 psi. Since the pressure is less than 2.38 psi everywhere except at the very bottom, the 5 psi is larger than the "real" load will be. I will have a 1.5" x 1" glued joint holding each 1" wide column of water, so the load on the wood joint is 5 / 1.5, or a little more than 3 psi. This load is WAY less than the strength of the material, and the joint is stronger than the material, so it should be safe by a large safety factor. Of course clamping/curing will be critacle for the joint to have anywhere near this ultimate strenght, but I think that if I through screw it with 3.5" screws every 3" along the length of the joint, from the bottom, that will be sufficient.
I intend to glue/screw the corner joints and the verticall 2" x supports in a similar fashion
About your lack of confidence in the amount-of-heat/temperature-of-water: I did a few numbers (engineer's favorite pass time! <grin>), and something is wrong somewhere!!!
If your engine is turning out 20 HP, it must have rejected/unused heat of something like twice that. Since don't think that you are capturing exhaust heat and lube oil heat and certainly not heat radiated off of the block, you SHOULD be getting about half of the waste heat, or another 20 HP worth of heat. Since you put all of this heat along with the electricity generated back into the storage container, you should be putting something like 40 HP worth of heat into the vessel. Since 1 HP = 2545 BTU (you can argue about European vs US horsepower, but that differance is only about 1.5%, so for purposes of this discussion, nevermind!), we should have something like 2545 BTU x 40 Hp x 4 hours = 406,400 going into the fluid storage container. If we have 240 gallons in the container, at 8 lbs/gal, we have 1920 pounds of water. Adding one BTU to one lb of water raises its temperature one degree F, no matter how you transfer the BTU to the water, so we should raise the temperature of the container 406,400 BTU / 1920 lbs = 211.67 F!!!! You report that your water heats an average of 75 F, so where in H#$L did the other 254,000 BTU go!!! <puzzled frown> Even if I make some assumptions about the amount of HP your making (Like you are off by 10%) and there is some loss from abient radiation and conduction and natural convection (Maybe another 10%) there is still close to half of the heat that is produced that is MISSING!!! <REALLY puzzled frown>
Energy can be neither created or destroyed, it only changes it "shape/form". like from the heat in a oil fired boiler flame to the energy contained in steam - so where it has gone, here, I have no IDEA!
That an internal combustion engine only puts about one-third of the fuel's energy into horsepower produced by the engine, is well established for about the last century. That the non-work energy is split roughly 50%-50% between cooling water and "other" is, similarly, widely held for about the last century. You can get p!$$y and argue that the thermal effeciency of an IC engine is not exactly 33%, and yes, you can find specific IC engines that are anywhere between 20% and 45%, but for a small diesel engine, I don't think that you will find a range larger than 30% to 40%, at the absolute outside limits. And, if your engine is a spark ignition engine, it efficiency is WORSE than a diesel, so there is still, yet, more, already, energy missing. I have absolutely NO idea where the answer to this is!
I can ask a lot of questions about how many amps at how many volts, yada, yada, yada . . . but I'm pretty sure that you know, at least to within 10%, how much energy your engine is putting out, so, help me out here, guys, what am I failing to see? There has to be a LOT of energy going somewhere - where is it???
If I take worst case examples and assume 10% error on all the measurements, there still is half of the heat from the engine missing! <frown>
On that question, I'll rest my convoluted case! <grin>
As always, thanx, eveybody for the input!
Regardz,
Wayne Stayton
Jens:
Ok, so we are not making 20 HP, here but 9200 watts. 1 HP = 746 watts, so you are actually making 9200/746=12.33 HP. If you capture all of the cooling water heat and half of the rest of the heat, and turn the electricity into heat,, you have a total load over four hours of 12.33x2.5X4 hours=123.33 hp-hr of heat into the thermal holding tank. At 2545 BTU per hp hr, you have 313, 861 going into the tank in four hours.
At 240 gallons x 8 lb/gal, you have 1920 lbs of water. Since your waste water heats up 75 F during the four hours, you have 144,000 BTU being stored in the water - that only leaves 169,861 BTU to be accounted for! <grin> You state that the the cooling loop loses about 5F between where it comes out of the engine and where it goes into the tank - do you have any idea what the flow rate is when this happens? Also, do you have any idea what the temperature loss of the tank is, per hour, after you shut the engine off, with the tank just sitting there?
Also, you say " loss inside the house is irrelevant " - well it may be irrelevant in terms of heating the house, but in terms of accounting for the heat discharged by the engine it is VERY relevant.
Since the tank is not insulated, the heat transfer from it is probably pretty significant but by far the easiest way to estimate this is to know the heat loss for an hour. If you make any sort of heat transfer estimate you have to make some estimate of the R value of the tank, liner, etc. and if your just shooting in the dark, as I am, your apt to make as many bad guesses as good one's.
Anyhow, I'm still confused as to where a BUNCH of heat is going, but your descriptions have pointed out where it might be. At least we now know, with some degree of confidence, what the total heat rejection by the engine is. It is true that you can argue about how much of the exhaust heat is really transferred to the water tank, but guessing that is half of the available non-water jacket heat, at least gives a place to start. It may be 45% or 55% of the non-water jacket heat, but that 5%, or even 10% is relatively meaningless in the greater scheme of things since we are trying to guess at a lot of other values.
If you have any idea about the temperature decline in the sitting tank, and about the rate of coolant water flow, I would, VERY MUCH, like to hear it - just as a matter of intellectual curiosity! <grin>
Thanx of reading, guys!
Regardz,
Wayne Stayton
Wayne, the direct conversions don't work out quite right here as they do not take into account generator and drive efficiencies... Because of that I think your numbers are actually conservative:) At any rate, running a listeroid myself, and having done some pretty carefull fuel use measurements, .125 gallons per KW/HR is a pretty close estimate for fuel consumption in a listeroid on diesel fuel. At 9.2KW of electric load, Jens is probably burning close to 1.15 gallons of fuel. That at 140000 btu/gal is around 161000 BTU/HR consumed. 1/3 of that into the cooling system(something I have also confirmed out of my cooling system heat exchanger) is around 53,666 BTU/HR. Half of that from the exhaust heatex is another 26,833 BTU/HR. The 9.2KW of electric heating elements works out to around 31,408 BTU/HR for a grand total of around 111,907 BTU/HR. Over 4 hours by my figuring, that is 447,628 BTU into the water...
But having been in on a few discussions IRT Jens system isssues, the numbers have never added up:)
I see you have fallen in love with the notion of making joints in the ply sheeting; I think Jens gave you good advice there.
The figures are quite likely correct for the strengths of Resorcinol glue on wood under ideal conditions; theoretical values that do not take into account field condition effects of dimensional changes from moisture, heat, uneven and out of line forces that lead to spot loading and thus incremental failure. Bonding to one face layer does not engage nearly the potential tensile strength of the whole thickness. Progressive failure; divide and conquor!
A scarfe joint or a double sided scabbed joint would have mechanical advantages but is way more complicated than the nature of the job warrants. Going to a larger tank has some apparent advantage in volume to perimeter ratio, but the strength in the whalers gives very quickly diminishing returns re. lateral deflection.
Also you cannot consider liquid in a tank to be a static load based on calculated pounds per sq. in. Vibration from traffic etc. is a very real and magnifying effect. I have been party to several shit outs of formed concrete. Someone apparently forgot about vibrating.
I dont feel the construction you have in mind would fail but it does have some potential negatives labor wise and there is some benefit in having your eggs divided between two baskets.
Ronmar:
Something dpesn't add up in your numbers . . .
You say: " .125 gallons per KW/HR is a pretty close estimate for fuel consumption" Diesel fuel is 6.7 lb/gal, more or less, and I kW-Hr is .746 HP-Hrs, so that works out to a BSFC of 0.624775
lb/hp-hr, to put it into numbers that I mean something to me. My Mercedes OM616918 has a published BSFC of 0.48 lb/hp-hr. Since the Listeroid truns slower than the Mercedes and fluid friction, which is most of the internal friction of a diesel engine - two surfaces moving relative to each other with a layer of oil in between, the Listeroid SHOULD have BSFC lower than the Mercedes, other things being more/less equal - they are both indirect injection, the Mercedcs has an OHC while the Listeroid is pushrods, but that should be only a small (2% max) differance . . .
You seem to agree that 1/3 of the total fuel load goes into the cooling water and you seem to agree that another 1/3 goes into exhaust heat+engine jacket+oil+..., so I think that you are agreeing that i/3 of the heat in the fuel also goes into power output, no? Well, if we have 12.33 hp made from 1/3 of the heat in the fuel, then we must be using 12.33 Hp-hr X 2545 BTU/hr = 313, 861 BTU going into the water each hour from the electricity. If the HP is 1/3 of the total heat energy output of the engine, we must have 3 times that all together going somewhere - so the total heat energy out put of the engine is 941,583 BTU/Hr. Using 140,000 BTU/gallon, we should thus have a fuel consomption of 140,000 / 941,583 = .67 gallons per hour. So, Jens, what is the fuel consumption of your engine? I'm betting it will be between the two numbers proffered above, but closer to mine - any takers on that bet? <grin>
Crofter:
I was thinking to bevel the mating edges at 45 degrees, and then apply my "scab" over that. I realize that isn't a true scarf joint, which would be at more like 15 degrees, but it is BETTER THAN A BUTT joint, no? My table saw, and my table saw skill, limits my joints to something more than 15 degree angles, and rather than make it a 30/60 joint, which is about the limit of what "I" can cut, and then have all of the monkey-motion of trying to make it a good fit, I went simple and opted for 45 degrees. Time will tell, whether this is a good, or a bad, decision! <grin>
About the joint being stronger than the materials - that is one of the reasons that I thought that I should use marine plywood, at something like three times the cost of exterior plywoood, since marine ply does have better gluing - both in technique and materials.
I have seen some marine plywood that has been tested to failure, and it did NOT fail along the internal glue joints, FWIW.
About drying/wetting making it weaker - that is why I was thinking to paint/prime the whole structure, interior and exterior and what kinda surprised me about Solar Gary's "tank" - it didn't look like he painted it at all, even though he was burying part of it in the ground. Paint/primer won't COMPLETELY eliminate swelling/shrinking but I think it will diminish it by at least a factor of ten!
Thanx for the input guys - all contributions greatly appreciated!
Regardz,
Wayne
Quote from: WStayton on April 08, 2011, 12:31:37 PM
Ronmar:
Something dpesn't add up in your numbers . . .
You say: " .125 gallons per KW/HR is a pretty close estimate for fuel consumption" Diesel fuel is 6.7 lb/gal, more or less, and I kW-Hr is .746 HP-Hrs, so that works out to a BSFC of 0.624775
lb/hp-hr, to put it into numbers that I mean something to me. My Mercedes OM616918 has a published BSFC of 0.48 lb/hp-hr. Since the Listeroid truns slower than the Mercedes and fluid friction, which is most of the internal friction of a diesel engine - two surfaces moving relative to each other with a layer of oil in between, the Listeroid SHOULD have BSFC lower than the Mercedes, other things being more/less equal - they are both indirect injection, the Mercedcs has an OHC while the Listeroid is pushrods, but that should be only a small (2% max) differance
That is why I made an earlier comment about you applying the direct conversions to these equations, they do not take into account real world drive and generator efficiency losses. Your BSFC numbers are for the ENGINE output in KW. The real world fuel consumption figure I provided is for the generator electrical output in KW, not the engine. It should be about 80% or so more than the engines raw BSFC. When you get your generator on line, I am guessing you will encounter similar fuel consumption figures. I have encountered comparable numbers with the few onan(kubota diesel engine) diesel gensets I work with.
Quote from: WStayton on April 08, 2011, 12:31:37 PM
You seem to agree that 1/3 of the total fuel load goes into the cooling water and you seem to agree that another 1/3 goes into exhaust heat+engine jacket+oil+..., so I think that you are agreeing that i/3 of the heat in the fuel also goes into power output, no? Well, if we have 12.33 hp made from 1/3 of the heat in the fuel, then we must be using 12.33 Hp-hr X 2545 BTU/hr = 313, 861 BTU going into the water each hour from the electricity. If the HP is 1/3 of the total heat energy output of the engine, we must have 3 times that all together going somewhere - so the total heat energy out put of the engine is 941,583 BTU/Hr. Using 140,000 BTU/gallon, we should thus have a fuel consomption of 140,000 / 941,583 = .67 gallons per hour. So, Jens, what is the fuel consumption of your engine? I'm betting it will be between the two numbers proffered above, but closer to mine - any takers on that bet? <grin>
Wayne.
1. I think you have a math error in there. 12.33 X 2545 is 31,380, not 313,861.
2. I fully agree that 1/3 of the fuel/BTU consumed exits thru the cooling system, as I have carefully measured it on my system. Where the other 2/3 go exactly I do not know as I have not built my exhaust heatex yet...
3. You can NOT possibly get more energy out than you put in, Sorry, I don't make the rules:(
4. And again, your use of these equations does not take into account real world efficiencies. For example, a good well proven rule is 2HP per electrical KW for SUSTAINABLE power generation. This rule takes into account real world drive and generation efficiencies. With that in mind, using your numbers, that 12.33HP/HR equates to 6.17 KW/HR. Now in this case since we are talking electric heating elements in water, which is a much more known conversion process, the standard conversion for KW to BTU is probably not far off the mark. So 6.17KW/HR X 3414 BTU = 21,047 BTU/HR into the water from the electricity generated with 12.33 engine HP...
I vote for one tote Mickey Moused to your engine and see where it thermosyphons to in 4 hours of loaded operation.
Casey
Jens:
I sort of disagree that it takes 2 HP to make 1000 watts of power - that would mean that your method of power generation is only getting about 2/3 of the power that the engine is generating turned into electricity. If you are losing a third of the power your are making, something is WRONG! I believe that the "2 HP = 1 kW' was dreamed up to cover the fact that if you have a spark ignition engine, in all probability you will be operating below the torque paek of the engine, so if you are at full throttle, i.e. 100% of available torque, adding .01 more HP to the requirement will cause the engine to slowly fold it's tent and quit! I also think that the rule of 2 HP per kW was introduced to allow some relief from running the engine at 100% and having it spit parts, though that is probably less of a problem with a Listeroid than with a more modern engine.
I think that I will have some losses in my setup, that was the principal reason that I wrestled with whether or not I should put a transmission in the drive train. Adding that transmission, takes about 5%(my guess- no known data that I could find) of the through power to overcome its internal fluid losses, etc, when it is in high gear at 1:1 gear ratio. If I have to use it in 3rd gear, the loss will be more like 10%(again, my guess - no published data that I could find) of the trough power. And, yes, there are some power losses in the lovejoy coupler that I intend to use, but those are more like 2% of through horsepower. The only other losses I will have are the bearing friction and cooling losses in the generator. Nobody publishes ANYTHING that even gives you a hint of what these losses are, but a rolling element bearing isn't going to be a real energy hog since you can walk up to a runing bearing and put your hand on it and NOT get FRIED, and if it is eating energy it must be getting changed into heat, there isn't any place else for it to go. So, maybe another 2% for the bearings (generous I think but . . .) The only other load is the cooling fan, and it doesn't appear to me to be a real hungry appendage - I would be very surprised if it was 5% of the rated power of the generator-head. So, if I am operating in fourth gear, there is 5% + 2% + 5% = 12%, which is a far cry from 33% Note: these are all predicated on operating at max power ie, the power loss is pretty constant - the bearings and the transmission and the fan don't care what power you are making, they have about the same load, no matter what. So, if I am losing 12% of the rated generator capacity, I have a waste load of 24kW x .12 = 2.88 kW, so will need another apx 3.9 horsepower. Since I don't think it is prudent to run at more than 85% of available hp from the standpoint of engine longevity, and I only have about 32 HP available, if I only use 85% of them, I only have 27 to play with. If the "friction" losses are 4 HP, I only have 23 left to make electricity, or 17 kW. If I am putting in 27 HP at 0.48 lb / hp hr (per the engine manufacturer), for a fuel consupmtion of 12.96 lb/hr. If I put in 12.96 lb/hr and get 23 hp in work, my "apparant" BSFC is .56, which is still substantially less than the apparent BSFC for your Listeroid, per Ronmar, which should be a more efficient engine than my OM616918. Unless you have a fluid coupling between your engine and your generator, the energy must be going somewhere and it almost certainly must be heat if it isn't electricity, and it isn't 33% of the power that the engine makes!
Energy is neither created or destroyed (unless you do nuclear fission/fusion, and then, e=mxcxc governs the energy flow) it must be going somewhere and it almost certainly is going there as heat - so, where is it? I don't believe that it takes 2 HP to make 1 kW of electricity, sorry!
I don't mean to be argumentative, but some things just don't stand engineering scrutiny(sp?). <grin>
By the way, what IS your fuel consumption while you are making 9200 watts?
LowGear:
Umm . . .there isn't really any way that I can do that, since the engine uses a pump for coolant flow through the engine, and there is another Jabsco pump to push raw water through the heat exchanger, so what you suggest isn't really possible without eliminating several parts in the system that SOMEBODY thought were necessary! I don't think they put ANYTHING in/on the engine just because it was pretty!
That's my story and I'm sticking to it! <smile>
Regardz,
Wayne Stayton
Wayne, if you do a little internet searching of generators up to say 50KW or so, you will find pretty consistently the 2HP per KW rule is applied. Above 50-100 KW the ratio typically drops a bit bcause the ammounts being dealt with are so large. I have run a lot of powerplants, some propulsion sets up to 3000HP and even those held pretty close to that rule(1.5MW). The 15KW onan sets I work with now at my remote sites have, you guessed it, a 30HP kubota diesel... You might be able to get away with less for a little while, but for reliable/sustainable power, there is a reason 2hp is used.
How many of your own KW have you made? I am guessing not many... Like suggested, power up your genset, wire up some load(baseboard heaters from surplus center work great and are cheap) and plumb on a barrel or one of those totes, and start making power and measuring fuel, heat and load. We can throw numbers back and forth and burn bandwidth till we are blue in the face, but untill you have done it yourself, it reaches a point where we who have, and have TAKEN DATA are just wasting our time... Good luck with your project...
"I don't mean to be argumentative, but some things just don't stand engineering scrutiny(sp?). <grin>"
Wayne, throw that calculator away; it is making you blind and deaf!
Raw data calculations are not a whole lot more worthy than astrological predictions if they ignore (or are ignorant of) field conditions that can often greatly modify the outcome. It is amazing how easy it is to get blindsided by some of them.
been too the land of Oz (kansas) moving, thus i am late to this party
here is my .02 worth on the topic (er rather the discussion on hp vs generator output)
the 2hp per kw generated thing is a carry over from the gas engine days, and remarkably it seems to work
fairly well for most diesel engine's as well.
in my opinion the reason it works for diesels too is largely based on folks not running their engine right up against rated hp
for long periods of time, the differences in manufactures hp claims, or some combination (or all) of these and other factors.
it seems to hold fairly true as a rule for the listeroids, while it is not so clearly so with the S195 changfa
the changfa is rated at 12hp continuous and 13.2 hp for a one hour rating, which might indicated that it ought to only make
somewhere between 6 and 6.6kw electrical. the reality is it will comfortably make better than 7kwatts continuous and over 8 on
a one hour rating, however...
the limiting factor is the cooling system, if you stick with the hopper cooling you will likely be limited to 6-6.6kw electrical output
to assure proper cooling and not have excessive water use. on the other hand with a water pump, radiator, t/stat, pressure cap etc
the engine will have assured cooling and can make more kw output based on the factory rated hp. but...
the bottom line is knowing for sure what the hp rating really is, therein is the problem
too many factors have a marked effect on hp, everything from differences in manufactures rating (from conservative to optimistic), differences in fuels, elevation, timing, intake and exhaust, injection quality, and other factors including the cooling systems ability to
maintain stable engine operating temps.
the following is from many hours of testing a number crunching
the s195 is about 31% efficient at converting diesel btu's to kwatt output
the st7.5 single phase head is about 78% efficient at taking this mechanical power and converting it to electrical power
about 32% of the waste heat exits the cooling system
about 28% of the waste heat exits the exhaust
the balance goes out with convection, radiation, production of noise (lots of noise) and via the lube oil
Vbelt drives are about 2% loss if designed properly, serp about half that if done right
all of the coolant rejected heat can be harvested and used if done right with a t/stat and pump, while only about
75% of the available waste heat from the exhaust should be harvested and used, otherwise the exhaust gasses will condense
and create other issues.
the s195 direct driving an st7.5 can produce right at 10kwatt/hrs of power for each gallon of pump diesel consumed, this only if the cooling system is such as described and the engine is ran at max output
for whatever it is worth, and your mileage may vary
bob g
ps. i have also found reference in a couple of places to the use of another formula for calculating generator output
for a diesel engine,
take the amount of power needed in KWe and divide by 700, the result will be the amount of engine hp needed to produce this
amount of power.
while it comes closer to explaining the changfa it is not quite right either, so perhaps divisor shifts from maybe 600-700 depending on
engine type?
One brief comment and then we'll leave this issue! <smile>
One loss that I have been stumbling over and had my eyes too focused on other things to see, and I am surprised that nobody else said something, is the heat loss of the generator proper. It is, I am sure, proportional to how much electricity you are making and I'm also pretty sure isn't accounted for in the horsepower requirements. I've got no idea what the amount truly is, and the "scientific" way to measure it, sticking the generator in a calorimeter full of water, will make MANY more problems than it will solve. Any generator that I have ever put my hand on has been at least warm and some were actually "hot", so I am sure that it is a significant heat loss, and the big dummy ("ME"! <grin>) was so busy beating on everybody for "looking the other way", that I completely missed/ignored it.
As to the beating on everybody to do things the "scientific" way: If sort of bothers me, being of a more less, orderly and thoughtful frame of mind, to see folks who estimate things by looking at the entrails of sheep, or the direction that the moss is leaniong on the side of a tgree where a dog has just pee'ed (sp?), but if you guys want to do things that way, far be it for me to try to introduce order and methodology into your world. I am curious, in fact some would say obsessed, to know the how, where, why . . . of things mechanical, but I do realize that some people prefer to just view the world as a set of "black boxes" that they twist dial "A" and result "B" occers, and they couldn't care less about why! So, I apologize foir trying to impose MY way of looking at things on everybody else - not everybody sees the world the way that I do, and I guess that is a good thing - if everybody looked at everything the same way, we would all drive the same autumobile in the same shade of gray with the same powertrain, etc., etc.
So, if I offended anybody, I am sorry, and I will make an effort to keep my "everything has to have a measureable, and accountable "reason for being" way of looking at things out fo everybody's face.
On that note, how about we close this thread out - we've learned all that we need to about using shipping containers for hot water storage!
Again, thaks for your input - whether I agreed with it or not!
Regardz,
Wayne Stayton
Quote from: WStayton on April 09, 2011, 10:41:42 AM
As to the beating on everybody to do things the "scientific" way: If sort of bothers me, being of a more less, orderly and thoughtful frame of mind, to see folks who estimate things by looking at the entrails of sheep, or the direction that the moss is leaniong on the side of a tgree where a dog has just pee'ed (sp?), but if you guys want to do things that way, far be it for me to try to introduce order and methodology into your world. I am curious, in fact some would say obsessed, to know the how, where, why . . . of things mechanical, but I do realize that some people prefer to just view the world as a set of "black boxes" that they twist dial "A" and result "B" occers, and they couldn't care less about why!
Wayne, I am very much the same way, and I have used many of those very same formulas to properly size components, or determine if my hairbrained scheme of the day is even feasable(never have found entrails or dog pee very usefull). But over the years I only continue to use the ones that I have proven thru experience to reasonably reflect reality... Get yours running, convert/transfer some energy and you will see what we are talking about...
Brainstorm alert on the EDPM thread concerning containers. Stay tuned and we'll reveal the truth right after these messages.
Casey
the problem with trying to do everything with formula and calculations is mainly with the fact that most folks eyes glass over long before
you get far into the weeds.
i am as guilty as anyone when it comes to trying to use scientific method and math to explain what i am either planning or observing with
experimentation.
what i have found to be most useful is the use of established methods and formula as a starting point to try and size components as close as i can to start with, then follow with carefully controlled experimentation with good instrumentation to see how close the reality is to what the math predicted.
once i get a sufficiently large body of data certain patterns emerge and replication of results start to also become apparent.
then i can go back and recrunch all the numbers, rerun all the calculations and tweak the constants to get an accurate set of formula that will allow me to predict with some degree of accuracy the performance of a specific engine/generator package under a specific set of parameters, using a specific fuel , at a specific set of load points etc. etc. etc.
what is key is coming to an understanding of what is happening, and being able to then lay out all the details so that someone elsewhere can replicate the same results using the same equipment under the same conditions.
you know you have it right when you can take the data and develop a logic problem to prove the results you are seeing.
as an example you know you are correct when you can prove through logic that your genhead is for instance 78% efficient and the engine is 31% efficient at a specific load when altering either efficiency would skew the other far outside what is likely for the opposing unit.
Ronmar and I have discussed and developed formula to predict the BSFC of a 6/1 driving an st5 across its output range to a high degree of accuracy a couple years back on another venue/forum. it takes a bit to get there and was only developed after we got a few data points established by careful observation/experimentation using good instrumentation.
in my opinion there are only a handful of folks that are really interested in working out detailed testing/ developing formulas and all that, however there are a few that are quite passionate about it, and once the formula is developed there are many more that will use it.
so in the end the result is generally always worth the effort.
also for what it is worth, there are at least a few published sets of data on commercially available generator sets and some cogen's
in the 4, 7 and ~12KWe class,
those sets of data are very useful as bench marks to compare to, you know you are doing well when you start to get close to the BSFC numbers the big boys get on their units, and really starts to get exciting when you can achieve better numbers than some of them
who's units can cost from 12k bucks to well over 30 grand.
also for whatever it is worth
it is a very good genhead (single phase) that can achieve 80% efficiency in the <10kva class, generally only the most expensive heads
can even come close and only at or near rated load. for an ST head the 78% number is likely very close to reality for most of them.
single phase heads don't get over 80% until you get up to or over 50kva or so, or spend over 2 grand for one. the losses seem to manifest mainly in heat, although there are some windage losses as well.
the rule of thirds is close enough for rough discussion when it comes to diesel engine's however the reality is likely quite different
the S195 changfa idi is about 31% efficient at best, while the 6/1 listeroid is in most cases no more than 28-29% efficient as generally deployed (but can be improved with better coolant temp control and a few other mods)
it is also very likely that either engine as used is likely much less efficient due to shifting, things like timing, leaky valves, slobbering injectors etc will reduce efficiency significantly over time, and this can be aggravated by alternate fuels and lack of proper setup and/or maintenance.
i mentioned earlier (and it might also have been noted by others) that the drive efficiency of a V belt can be about 98% (2%loss), but can be much worse if you don't follow good engineering and use quality components (pulleys and belts) losses over 5% can result.
generally serp drives do better if only because the engineering is generally worked out by someone else, the lack of cheap options also helps to keep the efficiency higher,,, generally speaking.
at the end of the day, if one is to get into serious testing, following scientific method, he will need some good instrumentation that is easy to use and interpret. things like a gram scale to measure fuel consumed, a watt/hr meter, a good thermometer, stop watch, load bank, volt, amp meters to name a few.
there are good electronic gram scales that won't break the bank, quality thermometers are also fairly inexpensive, and those electronic
kwatt meter heads can be programmed to read watt/hrs with very good and repeatable accuracy, they too can be found very inexpensively on ebay from time to time. load banks can be made up of surplus kitchen range heating elements, space heaters or any number of other methods.
an insulated coolant tank to measure recovered heat from the coolant system is also useful as is another for the exhaust if one is going to
try and recover exhaust heat and use it.
this is a topic i really like, even though it is getting astray of the OP topic a bit
bob g