Electric cars are a pipe dream

I understand it all, but again it is an irrelevant comparsion of a single square tube to single round tube. Has nothing to do with what I have claimed. Can't you understand and address my mathematically PROVEN claim? I.e. tell which number step in post 2151 has an error. If none does, my conclusion is mathematically proven.

 

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Good. But keep in mind that a corner fillet of one mm radius could be considered to be a quadrant of a 2 mm diameter tube. And the fact that at these pressures, 1mm is dozens of if not a hundred of mean free paths. I.e. the near corner region does not "know" it is not part of a 2mm diameter tube.

 

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Easily.

Your error is in the first step.

You start with the erroneous assumption that the wall thicknesses for a cylinder and a square at the same pressure are the same, but as I have shown they are not.

The walls of a cylinder are CONSIDERABLY thinner than a square for the same pressure gas.

Indeed I gave you a chart so you could figure out how much thicker a square tube has to be.

Hint: Cylinders can handle 20 to 120 times higher pressure for equivalent wall size of a square tube.

So you have to START with figuring out how much thicker a single Square tube has to be for the same pressure BEFORE you calculate how much you could possibly save on the total wall thicknesses by putting multiple square tubes together.

Arthur

 

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That seems true. Why I suggested that all corners have a 1mm radius fillet - I.e. eliminate the corners on the same scale as they do not exist in a 2mm diameter tube.

In other words, once you are 1mm from where the corner was, the pressure force is locally exactly normal to the surface, not at an angle as you suggest. At the fillet it is also exactly normal to the surface. I.e. every where only exactly normal to the surface force force exists, like in a round tube.

 

Absolutely.

From my source on Pg 77:

http://www.gowelding.com/pv/square.pdf

Arthur

 

I have already suggested that the two extreme edges of a flat 102 tube tank may need to "bow outward" and you do have a point that so do the top and bottom of each tube.

OK -lets go to the 3:1 rectangular cross section tube and the extreme of making all sides that need to bow into semi-circles.

Then the top and bottom arcs of each of100 of the internal tubes of the 102 tube flat tank with the internal walls spaced one unit of length apart, are a "split circle" or two separated semicircles. I.e. these two half circles have total arc length or perimeter of pi (which I will continue to call 3.14) just like the unit diameter circle does. Likewise with the total internal area of these two semicircles is 3.14/4 square units of area, again the same as the unit circle.

Note the vertical internal walls, each 3 units long in the 3:1 rectangular cross section case, are exactly flat as they have the same pressure on both sides; however, the area between these two three-unit-tall flat walls is 1x3 = 3.

Thus the total internal cross section area for each of the 100 internal tubes is 3 + (3.14/4) = 3.785 square units of area.

Now let's add up the total perimeter of one of these 3.785 cross section area internal tubes, but remember only one of these 3 unit tall walls "belongs" to each tube. (Its other vertical wall "belongs" to the adjoining tube.) That perimeter is 3 + 3.14 = 6.14 so the cross section area to perimeter ratio for an internal tube is 3.785/ 6.14 = 0.61645 but the ratio of the area of a unit circle (the two semicircles at top and bottom make one unit circle) to its perimeter is: (3.14/4) / 3.14 = 0.25

I am assuming here that the wall thickness everywhere in the 3:1 "rectangular" tubes is t and also than the unit circle has walls everywhere t thick. That is a necessary fact, not really an assumption. I.e. t is the wall thickness which just prevents the unit circle from being split into two semicircle by the internal pressure. Likewise the top and bottom semicircle of the 3:1 tube need walls t thick not to rupture or be "blown off" the 3 by 1 rectangle between them. Likewise the vertical internal flat walls need to be t thick, not to be pulled apart vertically by the forces on the two end semicircles. I hope this is clear.

It is not easy to put this into words. If you have any doubt I will try again. Point is that for both the unit circle and the 3:1 "rectangle" the walls are everywhere t thick. (I put "rectangle" in quotes as it is really a 3:1 rectangle with a semi circle of diameter 1 stuck on each end.)

Thus the Efficiency, E is just the ratio of the A to the perimeter, P or E = A/P since the walls are all t thick.

From above, for the 3:1 "rectangle" A/P = 3.785 / 6.14 = 0.61645 as stated earlier.

From above, the E for the unit circle is only 0.25 and recall ALL circles are equally efficient. Have E =0.25; for example to get a single circle which has the cross section area of one of the 3:1 "rectangle" (3.785 sq units ) instead of 3.14/4 sq units that the unit circle has, its diameter must increase by the sq root of the needed increase in cross section area or the larger diameter required is sq. root of {(4x3.785) /3.14} or sq root of 4.821656... or 2.1958 ... but this larger circle will still have E = 0.25 as the wall thickness and perimeter are both 2.1958 times larger.

I am tired and going to bed. Sorry if this is too long and confusing. Perhaps tomorrow I can state it more clearly but the efficiency of the 3:1 "rectangle" to the circle of any size is 0.61645 / 0.25 = 2.4658 or a little less when the 2 outer side tubes of the 102 flat panel are also considered. I.e. the 3:1 "rectangular" flat panel, with zero tendency to have any outer wall "bow out" as they are all arcs of a circle already, is about 240% more efficient than any circle, if I have no calcultion error.

 

Nope, same wall thickness of a rectangle only holds a tiny fraction of the pressure of a cylinder Billy.

Quit making shit up.

The data was posted that shows why we don't see rectangular pressure vessels.

Arthur

 

You may have built such a car differently - but it is, in fact, a purpose built natural gas car, made by one of the biggest car companies in the world.

A square cross section tank requires much thicker walls than a more spherical (in most cases, cylindrical) tank - and the additional piping makes it more prone to failure.

 

Yep. And if you look at the guts of any Level I or Level II charger, that's all it is - a cable with a GFI in it.

Yes, that's a Level III charger (DC.) It should be pointed out that you can charge at any rate with a Level III charger; it's only the faster (>1C) rates that Nissan advises against using very often.

 

That is true, but the Honda GX is just a very slightly modified Honda Civic, NOT a car designed for NG. I.e. the NG tank was just stuck in the trunk of a Civic, reducing the useful trunk space by 50%, etc.

A car designed for NG would have a full size trunk as the NG tank would be integrated into the body, probably a "flat panel" tank of more than 100 long, small cross section, rectangular tubes, adjoining side-by-side, so they share a common wall. I.e. each rectangle (except for one - one extreme edge of the "flat tank") has only three, not four, walls. This economy of walls, makes the weight of the tank very significantly LESS than the conventional single large round tank holding the same volume. This flat tank serves as the floor board and lowers the center of gravity, compared to a big round NG tank 100% above the floor board, improving the car's stability.

Below I give a crude cross sectional picture of the extruded floor board, which is also called the "flat NG tank", but image each of the "interior Cs" has only three straight sides:

CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCO This final O tube is the one that has four sides, but as I will soon discuss and illustrate below, it is really a "flattened D".

The C rectangles would be at least three times taller than their separation - the horizontal space between their centers. For example, they might be 1cm wide and 4 cm tall. If on average (they are shorter where the wheels are) in a front wheel drive car, they might be be 1.6 meters long. Thus, the average volume of one tube would be: 1x4x160 = 640cc or 0.64 liters. If the width of the car is 1.4 meters, then there could be about 125 parallel tubes. So the flat tank's total volume could be: 125x0.64= 80 liters, which is 21.134 gallons, bigger than most gasoline tanks, yet making the floor less than two inches thick.

That would be a "car designed for NG." More stable and with approximate the same travel range as a typical small car between fill ups and an equivalent fuel cost per mile driven of less than $1/gallon cost gasoline! If you want approximately 400 miles range between fill ups, make the roof a "flat tank" also - nice thing about NG is the tank does not need to be lower than the fill point connection as a gasoline tank does. Another nice thing is that there is no "sloshing around" when the tank is only half full. That also helps the stability - possibly compensating for the elevation of the CoG with a roof flat tank added for greater range. Some people have huge heavy baggage ON TOP OF the roof with little stability problems so I would not be concerned with an extra 100 pounds of NG, IN THE Roof.

Correct if speaking of one square tank, but not if speaking of 125 "side-by-side" tanks only 1 cm wide. I will admit that the top and bottom of each "rectangular" tube may need a little bowing outward as it spans the 1cm gap between the 4 cm tall vertical internal walls. I also admit that the two edge tubes of the flat tank also bow out significantly. Perhaps each is a 4 cm diameter semicircle.

Then the stress in the two edge tanks would be EXACTLY the same as in 4cm radius round tube. I would expect that 3, instead of 4cm would be adequate "bowing out" to safely span 4 cm. As the flat tank is extruded*, the two extreme sides of it could have thicker walls. Thus these two outer most tubes could only "bow out" 2 cm wide instead of be only 1 cm wide. Effectively the tank would have only 123, not 125 tubes or hold perhaps only 21 gallons, but even with a slight bowing out in the top and bottom sides of the interior tubes, as they span 1 cm between the "web supports" (also called "internal, strictly flat, dividers") the floor board this 21 gallon tank makes is less than two inches thick!

I.e. to again crudely illustrate the right edge of the flat tank (its cross section):

........CCCCCCCCCCCCCCCCCCCCCCCD with 123 of these tubes giving approximately a 21 gallon NG tank less than 2 inches thick, which also serves as the car's floor board. (The left most edge tube is the mirror image, but I can't print a reversed "D") I have not done the calculation yet for the 4:1 "rectangular" tubes, but based on the 3:1 calculation results, I guess the weight of the tank would be approximately 50% LESS than a 21 gallon single circular tank "eating up" more than half of the car's trunk!

Note that the weight economy is mainly, but not only, due to tanks having only 3, not 4, walls but also due to the fact than the wall thickness required is directly proportional to the diameter. Thus, much thicker walls are required by a circular tank which is, say 60cm in diameter, than one which has an effective diameter of only 1cm. True there are 123 of these "3-sided" tanks but they are 1.6 M long, not less than 1 meter before the diameter starts to reduce in the two hemispherical ends as needed when tank is placed sideways in the car's trunk. Also note that each interior tube of the 4:1 flat "rectangle" tank has 4 cm of flat wall and less than 3 cm of of curved wall for each tube's top and bottom. (Flat walls weigh less than curved walls do when spanning the same gap.)

Please join in the argument I am having with others, especially if you believe math analysis gives valid results even if they conflict with common practice of tank design.

* The extrusion would used a binder and short carbon fibers for strength - probably the same mix as used in Boeing's new 787 "dreamliner."

 

Clearly Billy has no expertise in engineering or materials and the proceeding is not based on anything but wishful thinking and ignoring the actual engineering evidence provided.

The fact is that rectangular tubes for the same wall thickness hold AT BEST 1/20th of the pressure. Indeed, the more rectangular the shape, the worse it is (square being best of the rectangular shapes) and yet Billy not understanding even the basics, chose a pretty poor 3 to 1 ratio.

The second fact is that SMALL tubes, like Billy is suggesting still have to hold gas at 3,600 PSI and thus would still need thick walls, which is why you don't see small tubes for sale for CNG because too much material is needed for the walls compared to the amount of gas the small tube could contain (in Billy's analysis he did not even consider the wall thickness issue)

Looking at what is available, it's clear that this is why small tanks just aren't made.
The smallest tanks are ~35 liters, over 50 times larger than Billy's hundred plus tiny material intensive .65 liter tanks.

http://www.fabercylinders.com/list/cng_l.asp?da=269&a=330

The Third fact is Billy has not been able to show ANY extruded tanks, indeed the composite tanks are all WRAPPED with continuous fiber each layer at a significant angle from the previous layer for strength. (he needs this extruded capability because no carbon fiber wrapping system or existing metal fabrication technique could actually build the overly complex tank system he designed)

http://lincolncomposites.com/products/cng-fuel-tank-sizes/

Finally, considering the pressures involved, after any accident with a tank molded into the frame, one would have to have those tanks inspected to insure their safety. Billy's design would make this inspection next to impossible and if damaged, since they are as Billy says, "integrated into the body" their replacement impossible to very expensive.

In contrast to Billy's BS, here's what is ACTUALLY happening in this field.
Notice no one uses rectangular tanks.

http://www.mcs-international-gmbh.de/downloads/mcs_cng01_engl.pdf

The only attempt to do something like this is to use pore storage, because the pressure is far lower:

http://munews.missouri.edu/news-releases/2007/0216-natural-gas.php
http://www.energtek.com/t/1008-ang-technology

Give it up Billy, you aren't an engineer and your poor understanding of the issues around CNG gas storage is blatantly obvious.

Arthur

 

Again just irrelevant comparison to existing SINGLE tank designs. Also still no indication of any error in the mathematical analysis which PROVES less weight for the "flat tank," made of many adjoining 1cm wide tubes sharing common walls (Most of the wall area in the 4:1 adjoining "rectangular tubes" are flat* as it has same pressure on both sides.) for less weight. i.e. until you point out an error in the math proving these flat tanks to be lighter for a fixed volume stored, I will trust the math in contrast to irrelevant facts about how a single round tank is much lighter than a single square tank. (And of course, I agree that the single tank should be round, not square or rectangular.)

*A flat wall covers a space, or spans a gap, with less material than a curved one does when the pressure on both sides is the same as it is for ~2/3 of all the wall in my "flat tank" design. The wall thickness in a 60cm diameter round tank MUST be 60 times greater EVERYWHERE, (all round the cylinder) than the wall thickness in a 1cm diameter tube of two semicircle sharing a common near5 zero thickness boundary plane between them with the pressure on both side of the boundary plane always the same. All of my "shared walls" are flat as they have the same pressure on both sides. They are 60 times thiner than the walls of 60 cm diameter circular tank.

If you like, you can think of these "internal shared walls" as "tension webs" only 1cm part which hold the outer walls of the flat tanks parallel to each other. - I.e. prevent the internal pressure from blowing the "flat" outer walls of the flat tank into a circular shape. That is really their ONLY function. The fact that the divide the flat tank in to many separate "tubes" is of no real importance.

PS - So long as you continue to ignore the math analysis of the adjoined mulit-tube "flat tank", I will continue to ignore your irrelevant articles about single tanks.Your attacking me, my qualifications, etc. a personnel attack is not the same as attacking my math proof.

I happen to have very good qualifications. - I'm a graduate of a special 5-year experimental program called "Engineering Physic" at Cornell University. Compared to the regular 120 or less credit hours, we had 175 credit hours when we graduated, but less than half of my entering class did - most transferred out to less demanding, 4-year, disciplines, like electrical or chemical engineering. Because of this high "mortality rate" Cornell discontinued the 5 year Engineering Physic program experiment. - It was too tough for most to make it thru but I did and kept my GPA > 85 as that was required for my "full needs" scholarship. The after that, I got my Ph.D. in Physics at Johns Hopkins in Baltimore, MD.

BTW, after that education, I worked 30 years at the Applied Physic Laboratory of JHU, always on some aspect of engineering and /or physics. Spacecraft, bio-medical implants, nuclear physic, high power lasers, fusion research, the HARM anti-radar air defense missile, ship defense against "sea skimming" cruse missile attack (especially the French Exocet, which was widely sold), etc. - you name it and I did it! (not to mention several energy systems, including installing and evaluating a wind generator for the US Coast Guard at their facility near Norfolk VA, 40+ years ago!)

What are your qualifications and why do you keep citing irrelevant articles?

 

LOL

Billy if you look at your cross section what you have done is created an eliptical cross section to your tank, but the much lower strength of that design has already been covered:

Which is why people who make their living building tanks for every purpose imaginable (and you can imagine that a lot of people would like a rectangular tank if it was practical) DON'T build them like this.

No one does.

But Billy thinks he is so much smarter than the people who make their living at this that he, in his spare time and only because it was brought up in this thread, has come up with a revolutionary way of making rectangular tanks that are 240% more efficient then what the entire high pressure tank building industry has been able to accomplish.

So Billy I bow to you INCREDIBLE intelligence and your REMARKABLE design skills.

Let it never be said that NOWHERE on the internet, has anyone as BRILLIANT as our Billy T ever posted such amazing insights.

BILLY, BILLY, HE'S THE ONE, IF HE CAN'T DESIGN IT, IT CAN'T BE DONE.

rotflmao

Arthur

 

Except for this, I will just ignore your post 2178 as it ONLY a personnel attack, not even a reference to an irrelevant article.
Again why not instead attack the math proof that the multi-tube (or internally tension webbed) "flat tank" is lighter for the same stored NG?

 

No Billy, It's clear that your internally tension webbed flat tank is nothing more than just two Elliptical tanks joined together with spaced internal webbing. But the engineering article I posted already covered that and explained that the required thickness of a hemispherical head is one-half the thickness of an elliptical one for the same design conditions, material, and diameter. And that doubling of required material isn't going to be eliminated by your internal webs.

More to the point Billy, why don't you explain why your supposedly brilliant design which according to you is capable of making rectangular tanks that are 240% more efficient then what the entire high pressure tank building industry has been able to accomplish so far, is not being hailed as the engineering breakthough that you so obviously think it is?

What's keeping you from making a mint on this Billy?

Arthur

 

I usually try to answer direct questions, even though, in this case I already have: (1) I'm at least 20 years too old (not enough time left to lose all and start over again and (2) I'm conserving my assets for my grand children. I am a self-made on salary, but with good investing, millionaire, not the billionaire needed to make an entirely new car.

Now you tell why you don't attack the math proof, instead of me - take that as a question.

 

Ah but Billy, you claim this is a SURE thing.

According to you your supposedly brilliant design is capable of making rectangular tanks that are 33% more efficient then what the entire high pressure tank building industry has been able to accomplish so far.

Clearly they would pay you handsomely under a NDA for your idea.

No Billy, as I pointed out earlier your internally tension webbed flat tank is nothing more than just two Elliptical tanks joined together with spaced internal webbing. But the engineering article I posted already covered that and explained that the required thickness of a hemispherical head is one-half the thickness of an elliptical one for the same design conditions, material, and diameter. And that doubling of required material isn't going to be eliminated by your internal webs.

Indeed your math is filled with flaws, like: Note the tension in the walls of the square tube and the round tube is the same so the wall thickness is t for both with the same safety factor and same internal pressure

Yet the engineering article I posted says something quite different:

Arthur