[yogeshnaik]

Idea is good. The suggested idea is implemented in Fighter planes. The fuel tank will have bladders which inflate after the fuel is filled. It is expensive too.

[Psycho]

1) What if you had a flat surface as a fake roof that moves up and down in the tank and is settled on the liquid fuel wouldn't that reduce evaporation?
2) If you have a good gas tank cap and no leaks in your hoses, your evaporation will reach a particular point and stop.
3) If you had more fuel in the car tank in the first place your evaporation would again reduce as you have lesser space for the gasses to occupy.

but still I still feel non leaking hoses and a good tank cap is still a decent solution.

[Lalvaz]

Brilliant idea Driverace, I'm sure there are lots of issues that will crop up during the implementation, but I like the kind of fresh thinking you have. Keep working on it, and I'm sure you'll learn a lot in the process, (even if your idea fails), BTW, I dont think its that difficult to overcome most of the obstacles pointed out by others.

For ex: for determining the volume of petrol left, I could use a sensor to weigh the balloon and calculate the volume of fuel left.
Also although the baloon will need to be replaced every so many years, it will also result in eliminating fuel tank cleaning. So, you change the rubber balloon every 3 years and come up with a brand new fuel tank.
As regards the volume of fuel being lost due to evaporation, well, no one knows how much is lost, cos no one measures it.

Keep working on the original idea, you might just hit bullseye.

[Sankar]

The bladder is not elastic, bladder will crumple down as the volume of fuel decrease, crumpling reduces the available free space inside. Since fuel is contained within a bladder fuel remains cooler too.

Fuel cell bladder is safer in the event of a crash, thats why racing adopted it. BUT these bladders do not last the life of the vehicle, it has to be periodically replaced. Since most of us Indians have a chalta hai attitude no one will spend money to replace the bladder until its too late.

For the masses whats needed is an idiot proof solution. Balloons and bladders won't work.

[singh.amrit]

Problems (as per my knowledge ):

1- Material of the tank, you will need a material with very high barrier properties ( to prevent vapors going through the rubber ), which are not usually elastic, an elastic material will have gaps in its structure to allow for coiling / uncoiling of polymer chains.

2- Petrol is an organic solvent ( a part of it is ) as we all know, hence , material will again prove to be a hinderance.

In short, if its expandable, it will have very high leakages.

what you can focus on instead, is the design of the fuel tank,
like :
or something better, it should have different compartments, one used after the other, hence, lesser vapors at a given time in theory.

[driverace]

Originally Posted by Psycho

Here are a few points that work against your idea:

1) you still need a metal casing for safety purposes
My idea starts with,
"Method:
I suggest we have a expandible Poly-Ethylene (high grade Plastic) forming a baloon like structure inside our fuel tank...,
2) Plastic is not elastic in nature hence ruled out
3) Rubbers harden over a period of time ruled out
I have not zeroed in on material yet!, Just mentioned what I require the material to do for it to work!
(the kind of technology we have here,, i dont think its going to be long before we find one.. and now I sure will !!

4) Well a good fuel tank with proper hoses and a decent tank cap does not allow the petrol to evaporate until it reaches a particular pressure, hence keeping the gaseous petrol inside the tank.

Dear Psycho , every fuel tank has breather arrangement.
It will allow to maintain a atm. pressure inside the tank, by allowing controlled ingress of air!, If air can go in--fuel (vapours) can come out too! ..

5) A balloon kind of structure will not be centrally positioned hence will add to the de-stability of the car based on the fuel in it.

Rather!, The Balloon kind of structure if sort-of-tied to the top of the tank and to the bottom will move the C.G. of the fuel volume as less as possible (definitely less than its free state.. )
Do tell me, If I need to explain more on this !!

6) you could run a fuel pump agree but what about fuel level only option is weighing, again wont work as the balloon can not be positioned in one place

Thank you Sprucegoose for thinking upon that !
7) Again "The tendency of the balloon will be to empty its contents, hence keeping the fuel under slight positive pressure at all times." would mean flooded carbs if you park for a longer duration i don't think it will make a difference in case of an MPFI car
Again, Not Many Carbs around in cars I think!
and, Sprucegoose, thinking about the cut off valve also was the first thought that came to me ! , thanks..

8) It cannot give you a long life as elasticity will reduce over a period of time.
Will work more on that.. and get back with proper material..

9) Your statement "and I think it sure will add to the FE 10+percent.. depends on the running/filling patterns/standing time/ambiente' temperature !!" is so a guestimate that it does not even begin to make sense.
Thank you for that!, I will try to come up with figures !
Hence I still believe in point 4 more than anything else. so stick to the original fuel tank.

Thank you for your 'contructive' criticism !!

Originally Posted by Shan2nu

A tank needs to breath only when its rigid, since its volume remains the same irrespective of the amount of fuel inside. But a flexible material like a rubber balloon will expand and contract wth rise and fall in fuel level.
Thank you for that explanation Shan2nu!,
I think you understand what I want to say closely

....
.....
I think race/sports car are already using this to prevent fuel from flowing to one side of the tank when conering.

I rem Wolf having to abandon his track session midway due to the fuel moving away from the fuel pump inlet cutting off the fuel supply to the engine, everytime he cornered hard. I filled another 10ltrs of fuel in the car before my session and faced no issues.

Nice to know that bit !

Shan2nu

Originally Posted by SamtheLeo

My 2 Cents :

The amount of money spent in the making & maintaining such a Elastic balloon (as it may have leaks & other issues) will certainly over run the price of the fuel which is lost due to eveporation currently. SO the first question is Does it make economic sense.
Thank you ! for your feed..
Lets calculate that after the quality and safety part is ensured!,
How much fuel do you think we loose due to evaporation normally. I dont think it is that a great amount.
For that, we can put a spoonful of petrol in a beaker, see how fast that evaporates!

Originally Posted by BaCkSeAtDrIVeR

It was mentioned somewhere here that having a sort of "floating cover" on the fuel surface to prevent evaporation is compulsory as a part of Euro IV compliance.

I also remember reading that faintly though!, thank you backseatDriver!
that norm was in concern with safety I guess..

Originally Posted by n.devdath

+1 to that. The amount of fuel lost due to evaporation is very less if the vehicle is parked under shade and kept at a cool place.
Well, I have started off considering general usage, definitely I will consider the best case -worst case for further explanation..
though what you suggest still would result in considerable volume of evaporation!!
..There is no point in over researching the issue here.

Thank you for your opinion !
Take care..

Originally Posted by Sprucegoose

If the baloon has peizo electric strands in them then,
1> depending on the amount of strain they will out put a certain amoutn of electricity. that way the amount of fule can be checked.

2> if current is applied to the strands then they can be made to contract, hence negating the requirement of a fuel pump.

A cut of valve can be put to further restrict the amount of fuel flow.

Thank you Sprucegoose!
But the fuel could continue to evaporate inside the baloon, creating an vapor bubble which will throw off the fuel gauge.
About that.. I planned a vent, which is supposed to even feed in the air intake-- i.e. again resulting in burning the evaporated fuel too!!

Originally Posted by rajeev k

This resembles an Accumulator used in Turbine governing systems. THe accumulator has a baloon inside, which is filled with NItrogen which in the event of a sudden pressure drop inflates and pushes the oil into the system.
The problem in car fuel tanks would be whether the fuel can press against the gas pressure of the baloon.
Any how try.
Yes, it does..
I think it more resembles Oil reservoir in a Station TRansformer / Generator Transformer!
wlll post the analogy later..
but the purpose there is to stritcly keep off H2O from Oil.

Originally Posted by yogeshnaik

Idea is good. The suggested idea is implemented in Fighter planes. The fuel tank will have bladders which inflate after the fuel is filled. It is expensive too.
Thank you for your feed, But I think, we can go for a lesser graded 'bladder' than the one used in the jets.. and lesser requirements from the 'bladder' wrt jets..
But, I will surely put a calculation to that..
Lets see if it qualifies as a economy prod. or something else! (perhaps performance prod as its used in race cars/sports as mentioned by friends earlier.!!

Originally Posted by Psycho

1) What if you had a flat surface as a fake roof that moves up and down in the tank and is settled on the liquid fuel wouldn't that reduce evaporation?
So you are suggesting "moving surfaces" with "sliding (metal/nonmetal) contact" with "sealing requirements" in the tank filled with inflammable liquid
Nice!! No comments..
2) If you have a good gas tank cap and no leaks in your hoses, your evaporation will reach a particular point and stop.
There is a breathing facility in every fuel tank..
you may agree on that, so there is provision for air to come in/equal opportunity for the formed vapors to escape out!!, no saturation of vapors, just more scope for vapors !!
3) If you had more fuel in the car tank in the first place your evaporation would again reduce as you have lesser space for the gases to occupy.
Ok!, but we really cannot expect people to fill their tanks to fill to the brim & keep them that way all the while!!( and I am not asking anybody to do so!)
The cars will run, and the fuel level will go down !!
On the contrary if you do not use the vehicle for long time its even recommended to drain the fuel and store it safer!

but still I still feel non leaking hoses and a good tank cap is still a decent solution.

Ok..

Originally Posted by Lalvaz

Brilliant idea Driverace, I'm sure there are lots of issues that will crop up during the implementation, but I like the kind of fresh thinking you have. Keep working on it, and I'm sure you'll learn a lot in the process, (even if your idea fails), BTW, I dont think its that difficult to overcome most of the obstacles pointed out by others.

Thanks a lot for your support and your kind words!!
I appreciate it a lot, and I am even more motivated to work further..

For ex: for determining the volume of petrol left, I could use a sensor to weigh the balloon and calculate the volume of fuel left.
Also although the baloon will need to be replaced every so many years, it will also result in eliminating fuel tank cleaning. So, you change the rubber balloon every 3 years and come up with a brand new fuel tank.
Now, I swear, I did not think of that!
That tank cleaning cost, I can consider in my calculations, I guess
As regards the volume of fuel being lost due to evaporation, well, no one knows how much is lost, cos no one measures it.
Yes, But, I am sure, about the volume, since a visual idea is right in front.. as in splashing of oil that takes place, we can only imagine! with all the bumps, speedbreakers, and more!
I will try to come with figures to get a hold-support to what i propose!
Keep working on the original idea, you might just hit bullseye.
Again thank you for the positive energy!

Originally Posted by singh.amrit

Problems (as per my knowledge ):

1- Material of the tank, you will need a material with very high barrier properties ( to prevent vapors going through the rubber ), which are not usually elastic, an elastic material will have gaps in its structure to allow for coiling / uncoiling of polymer chains.

2- Petrol is an organic solvent ( a part of it is ) as we all know, hence , material will again prove to be a hinderance.

In short, if its expandable, it will have very high leakages.

what you can focus on instead, is the design of the fuel tank,
like :
or something better, it should have different compartments, one used after the other, hence, lesser vapors at a given time in theory.

I will surely study that more.. thank you too..

I wanted to say further more,
thank you for your feed and the kind words above.
I am studying more about the material and nature of material as expected.
How far can we justify it economically (since I am suggesting it as a FE improvement device to begin with!)

More to say,
I feel the astronomical averages that we see in the "Mileage Rallies" that we see and read, might just be the answers as to how much fuel "may be" lost in evaporation!!..
I am saying just may be !! since they dont at all waste any time after the fuel goes in, I think..
(Is that so? anyone?)

P.S. Sorry for the delay! had a 24 hr marathon at work on Monday!!

Care.

Ace.

[Psycho]

Originally Posted by driverace

Originally Posted by Psycho
1) What if you had a flat surface as a fake roof that moves up and down in the tank and is settled on the liquid fuel wouldn't that reduce evaporation?

So you are suggesting "moving surfaces" with "sliding (metal/nonmetal) contact" with "sealing requirements" in the tank filled with inflammable liquid
Nice!! No comments..

Well i don't think you understood, if you have a film on top of a fluid where does the evaporated fluid go??? It condenses on the film.

Similarly imagine being able to have a simple flat plastic sheet in the shape of the tank that would effectively float on top of the fuel, what would that do???

Originally Posted by driverace

4) Well a good fuel tank with proper hoses and a decent tank cap does not allow the petrol to evaporate until it reaches a particular pressure, hence keeping the gaseous petrol inside the tank.

Dear Psycho , every fuel tank has breather arrangement.
It will allow to maintain a atm. pressure inside the tank, by allowing controlled ingress of air!, If air can go in--fuel (vapours) can come out too! ..

Well a simpler solution block the breather with a 1 way valve that allows air in but not out.

[driverace]

Originally Posted by Psycho

Well i don't think you understood, if you have a film on top of a fluid where does the evaporated fluid go??? It condenses on the film.

I have mentioned clearly in my earlier threads that there will be a venting arrangement that will be out to air intake of cylinders!
'That' is where the vapors will go!,
If it condenses, it will settle back in the bladder too!

Similarly imagine being able to have a simple flat plastic sheet in the shape of the tank that would effectively float on top of the fuel, what would that do???

Now Plastic sheet!, thats coming close to my balloon idea in the first place!
But again the plastic sheet behavior while filling/turbulences inside the tank/ and may end up still allowing some fuel to come on top of it..
You can visualise the same with analogy of a plastic bag floating on water, it floats alright, but againit allows some water to come over it too!, that defeats the whole point of putting the plastic!


Well a simpler solution block the breather with a 1 way valve that allows air in but not out.

I am not sure how will that work, But I think that is a good idea too!

Its nice to see that you are putting so much thought into this too!
and, coming to the point almost identical to where I started thinking about solution for this, and came up with this balloon-concept!

I will post up a sketch today.
<after office!>

Care.

Ace.

[Sprucegoose]

rather than a baloon, how about having a large piston esque tank.
problem will be making it petrol / diesel tight.

you'll have fewer problems...

but the mechanics might be haevy & bulky, which would negate any advantage gained.

Edit: Piston with a large cross section & lower height

[alpha1]

First of all does anyone here has some figures for how much petrol is actually lost in evaporation?

[lsp]

Design inspired by the Gobar Gas plant design, in which the tank can rise up when the gas starts to accumalate.

• The fuel tank is a small modification on the normal fuel tank.The top plate (lid) of the fuel tank can move up down. The movement is linked to the fuel tank cap.
  
• The lid has a valve which would allow air to go in the tank when the lid is lifted up and the air to go out when the lid is pushed down.
  
• When the fuel tank cap is open the lid lifts up to its maximum position allowing fuel to be filled in to max capacity.
  Figure 2
  
• When the fuel tank cap is screwed back, the lid will slowly move down (under the influence of gravity) and rest at level with the fuel.
  Figure 4
  
• Fuel pump sits at he bottom of the tank. Unlike the normal fuel pumps, a more flattened one would be better suited for this design. I dont know if thats feasible.
  
• The lid, owing to its weight or some other mechanism, would always be in touch with the fuel surface and hence minimise the amount of air or blank space for fuel to vaporise.

Design drawbacks:-

The lid mechanism can be hard to create.

The best fuel tank shape to suport this design would have been long cylindrical fuel tank, but we all know that owing to the positioning of the tank it is not possible to have it in that shape.

Please provide your comments about the design.

[gharika]

Well the Bladder idea was actually used in World War II fighter aircrafts from US. It saved many a life as it prevented explosion of the vapors. Its good from a safety point of view but there is a rare chance of the fuel tank getting hit in a car

Also, before getting into the theory of the new design, it will be good to get an estimate on the loss thats happening in the typical design. Lets first find out what we are trying to save.

[driverace]

Originally Posted by Sprucegoose

rather than a baloon, how about having a large piston esque tank.
problem will be making it petrol / diesel tight.

you'll have fewer problems...

but the mechanics might be haevy & bulky, which would negate any advantage gained.

Edit: Piston with a large cross section & lower height

Well,
Some clarifications on my line of thinking:
I started to think about this, with a sliding/fake roof for the tank.
but that I had to dismiss, as anything like "friction" inside the tank is not a good idea, particularly when we are talking about such high grade inflammable fluids!
Either

1. Its metal to metal contact:
which means better sealing, but at the risk of sending in sparks, which is uncompromisable!
(even though we are talking about greater diameters and lesser bores)
2. Its a nonmetal contact: e.g. asbestos
which means sealing will degrade faster, will even shred bits inside the tank which we dont want at all!, and leading to early leakages
(here somewhat a lesser risk of sparks)

I dismissed this line of thinking owing to the shape and volume restriction/requirements of our Fuel tanks
plus - the modification/fabrications requirement!

Originally Posted by lsp

Design inspired by the Gobar Gas plant design, in which the tank can rise up when the gas starts to accumalate.
...
The lid mechanism can be hard to create.
YEs, but achievable (without major risk of sparking as written earlier)

The best fuel tank shape to suport this design would have been long cylindrical fuel tank, but we all know that owing to the positioning of the tank it is not possible to have it in that shape.
Thats the reason i felt the need of a "mouldable" device to work our trick!
Please provide your comments about the design.

Thats nice thinking ! Can be indegeniously developed as a replacement FT to standards!
Let me know your developments too!

Originally Posted by alpha1

First of all does anyone here has some figures for how much petrol is actually lost in evaporation?

OK.
Its really high time, I should start some work with that.
I was searching up that and more.
But All I got was that, its all dependent on the vapor pressure, and that (just like octane no.), volatility is defined with a reference point being "Propane".
Can anybody help me to get a number here?

Meanwhile,
I have found this link:
MAHALAXMI RUBTECH LIMITED

The exact same product I am talking about.
Just the intention here is to keep the contents of the air-cell to get in contact with any moisture from the air that will exist in rest of the tank!
Whereas my intention is pretty much inline with the intention of the linked product!

Working on: Volatility Index/ Calculation of evaporation rate and dependency on surface area.

Care.

Ace.