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Pressurized Fuel/Air Mixture

09/15/2021 8:42 AM

I remember seeing a blow torch,the type that used gasoline as a fuel.

It burned with a pure,clear blue flame.

The fuel was pressurized in the fuel tank and was vaporized as it left the nozzle and was ignited by the hot nozzle,which had been pre-heated by a fuel bowl underneath the nozzle.

Gasoline that is not pressurized does not burn that cleanly,so I think the pressurization of the fuel forces oxygen,as well as all of the other atmospheric gases into the fuel.The result is a cleaner burning fuel.

I emptied the fuel tank of the blow torch into a container and noticed that it was bubbling like a carbonated beverage.

I suggest :Feed highly pressurized,(with atmospheric gases) fuel instead of ambient pressure fuel into a internal combustion engine.

This will increase the available oxygen in the fuel,and make the atomizing of the fuel more efficient when the pressurized air/fuel hits the vacuum of the combustion chamber,like shaking a soda and popping the lid.

I think this principle should be tried in internal combustion engines to improve combustion and reduce pollution.

I know fuel pumps slightly pressurize the fuel,but not in the presence of atmosphere,and not at very high pressure.

Perhaps diesel engines could incorporate this at the pre-injector stage where the pressure is highest,and/or gasoline engines could use a small auxiliary pressure tank.

Of course,the engine control computers would need to account for the added oxygen content and adjust mixture accordingly.

I realize this may have already been explored and had no merit,but just in case:

I put this idea in the public domain so that it may be freely utilized by anyone,and not sequestered or claimed by any single entity.

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#1

Re: Pressurized Fuel/Air Mixture

09/15/2021 11:28 AM

I think the compression stroke of a piston engine does exactly what you are describing.

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#2
In reply to #1

Re: Pressurized Fuel/Air Mixture

09/15/2021 11:45 AM

That is true,but there is value in oxygen laden fuel,like alcohol.

I think pressurizing the fuel/air before combustion may be of a benefit..maybe not so

much, but worth exploring anyway.

Pressurizing the fuel/air to a much greater pressure than the engine compression at

the time of injection would make the fuel/air atomize more thoroughly,especially

when the engine is cold.

This could reduce or eliminate piston "wash down" contamination of oil which occurs

on startup of a cold engine.

I also think the better atomization of the fuel will help efficiency.

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#7
In reply to #2

Re: Pressurized Fuel/Air Mixture

09/15/2021 10:27 PM

Yeah nitrous oxide injection...that is a thing....

What is a high pressure fuel pump?

The high-pressure pump is responsible for compressing the fuel supplied by the electric fuel pump to the pressure required for high-pressure injection up to 20 MPa (200 bar). around 3k psi

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#9
In reply to #7

Re: Pressurized Fuel/Air Mixture

09/16/2021 3:33 AM

https://www.convertunits.com/molarmass/Nitrous+Oxide

Element

Symbol

Atomic Mass

# of Atoms

Mass Percent

Nitrogen

N14.0067263.648%

Oxygen

O15.9994136.352%
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#3

Re: Pressurized Fuel/Air Mixture

09/15/2021 4:03 PM

Pressurizing the fuel to overcome the chocking of the nozzle actually increases its speed when exits the nozzle where actually its pressure drops, by design even vacum is produced localy and that kinetic energy and fast turbulant motion is really what makes it absorb and mix with air, making efficient combustion possible. Because as we know liquid fuels actually don't burn, only their vapors do, having the chance to come in contact with oxygen. Preheat also helps here, more so on thicker, less volatile fuels. On gasoline for example, preheating is not even necessary. But it does improve burning efficiency. The risk factor with heavier fuels is that since pressurizing was obviously done with air from a hand pump this under certain temp conditions is succeptible to self-ignition, creating disaster. The same self ignition that we exploit on diesel engines. Anyway I don't think pre-mixed pressurized air-fuel is a good Idea anywhere except in a combustion chamber. (That will likely survive even if you have ignition at the "wrong" time that is) The best you can do is (high pressure) direct fuel injection INSIDE the already fully pressurized combustion chamber milliseconds before ignition. And it's already done in production (for exomple by a company that is also famous for manipulating engine memory maps depending on car being during emission testing or not. Enough said. And by now possibly by others -it is rather technically challenging because gasoline does not provide nearly as good lubrication as diesel fuel to components (pump parts, injectors, solenoids etc)-. S.M.

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#10
In reply to #3

Re: Pressurized Fuel/Air Mixture

09/16/2021 3:40 AM

You are correct about the lubrication ability of diesel fuel.

There are many engines and generators,forklifts,etc. from Iraq that were junked

because of using jet fuel in them when they ran out of diesel fuel.

If they had added oil to the jet fuel,it would have been fine,but they didn't and the

fuel pumps locked up.

Plenty of large generators on the gov. surplus block.

The military is now specifying all new engines to use the same fuel so this will not

happen again.

It will also simplify deliveries by having a universal fuel.

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#4

Re: Pressurized Fuel/Air Mixture

09/15/2021 4:20 PM

I have an old Coleman lamp that works like that. You put gasoline in the tank and pump it up. The gasoline burning in the mantle puts out a lot of light.

My guess is that the gasoline/air ratio is more accurately controlled by vaporizing liquid gasoline and mixing gasoline vapor with air as is done with carburation or fuel injection rather than dissolving air in gasoline first.

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#5
In reply to #4

Re: Pressurized Fuel/Air Mixture

09/15/2021 4:58 PM

I don't mean substituting the fuel air mixture system that exists,but possibly

improving it with a oxygen rich mixture.

Not pure oxygen,just atmospheric (about21%).

I realize that the Engine Control Module on modern cars regulate the fuel/air mixture

by getting a signal from the Oxygen Sensor and other sensors on the engine.

I may experiment with a lawn mower engine which is carbureted,using a blow torch

tank(no flame) to pressurize the fuel,then emptying the bubbling fuel into the gas

tank of the mower.

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#6
In reply to #5

Re: Pressurized Fuel/Air Mixture

09/15/2021 9:01 PM

So, I think what you are driving at is getting more air and gasoline through the same engine to get more power, but by dissolving air in the gasoline rather than pressurizing the air with a supercharger.

The stoichiometric mixture for gasoline to air is 1:14.7 by weight. So, for example, to double the amount of power of your engine would require dissolving an additional 14.7 grams of air in 2 grams of gasoline to maintain the stoichiometric ratio (1:14.7).

Air–fuel ratio - Wikipedia

The density of gasoline is 0.75 g/cm3 so 2 grams of gasoline would occupy 1.5 cm3.

The density of air is 0.0013 g/cm3, so 14.7 grams of air at STP occupies 14.7/0.0013 =11307 cm3. So you would have to dissolve 11000 cm3 of air in 1.5 cm3 of gasoline.

It's an interesting idea, but there is no way to dissolve that much air in gasoline. A supercharger that doubles the air pressure (density) would accomplish the same 2:1 power ratio.

https://www.aqua-calc.com/page/density-table/substance/air

www.aqua-calc.com/page/density-table/substance/gasoline

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#8
In reply to #6

Re: Pressurized Fuel/Air Mixture

09/16/2021 3:28 AM

Not trying to increase power,merely trying to possible increase efficiency of the

combustion.

I have studied the modern car combustion systems since my first post and I see how

they have exploited nearly every means to improve efficiency of the fuel

burn,including piston shape,combustion chamber shape,placement of spark plugs

and ignition timing,monitoring air mass and temperature,load,ignition and fuel

injection timing and duration,re-burning of rich exhaust,and many other fine tuning methods.

After due consideration,I do not see much room for further development in the

fuel/air control system.

My idea is dead in the water.

Destination:File 13.

The main focus now is in the mechanical portion of the engine,such as valve

timing,variable displacement,etc.

Opposed piston diesels are an old technology that is much more efficient than the

current diesels,and cheaper to make,requiring no valves,no heads or head gaskets.

They are also much more durable and reliable.

They were used in ships in WWII

because of the simplicity and durability and power/weight ratio.

It would require a lot of capital to design new manufacturing processes for this

technology,but the demands for CO2 reductions may force it.

You gave a very good technical explanation why my idea would not work.Thanks!

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#11
In reply to #4

Re: Pressurized Fuel/Air Mixture

09/16/2021 3:47 AM

We used to have a kerosene heater when I was a kid that worked by pump....I always had to keep pumping it up, but man when it was pumped up it would really put out some heat....don't see 'em anymore...

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#15
In reply to #11

Re: Pressurized Fuel/Air Mixture

09/20/2021 4:48 PM

You can still find mil surplus camp stoves that work on same principle,but they use gasoline.

Lots of other stuff too.

https://www.govplanet.com/jsp/s/auction.ips?msg=64898&kwtag=auctionsec2

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#12

Re: Pressurized Fuel/Air Mixture

09/16/2021 5:06 AM

I think you might find that the fuel burned well in an unpressurised atmosphere, where in a cylinder the small atmosphere is pressurised. There is a difference from creating a flame to creating an explosion in a controlled chamber. And I guess the crankshaft and con rods would need to be beefed up, making the engine more costly and heavier.

Just build a $5 hydrogen cell and install that under the bonnet, then you have no pollution problems.

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#13

Re: Pressurized Fuel/Air Mixture

09/20/2021 7:59 AM

Recommended viewing, from 19 minutes in.

The pressure at which combustion takes place is of little substance.

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#14
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Re: Pressurized Fuel/Air Mixture

09/20/2021 1:38 PM

Maybe I misunderstand your statement but without compression you wont turn the crank. The more compression one gains the fuel burns more evenly creating a larger explosion, (more intense), therefore more downward thrust on a piston. No compression, no thrust.

Loose compression in a 4 cyclinder engine and the engine runs poorly.

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#17
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Re: Pressurized Fuel/Air Mixture

09/21/2021 5:39 AM

Whatever.

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#18
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Re: Pressurized Fuel/Air Mixture

09/21/2021 7:28 AM

Your 'whatever' moment explained:

Compression ratio is the ratio of volume occupied when the piston is at the bottom of its stroke to the volume, when the piston is at the top of the stroke.

The higher the compression ratio, the higher the thermal effieciency is. This is because when the energy of combustion is released as thermal energy it goes into expanding the combustion gasses. The air/fuel mixture is mostly nitrogen which is inert. As these gasses expand they are limited by the combustion volume. Since at any given point in the piston stroke the volume is fixed, the remaining quantities in the ideal gas equation,(which only loosely applies but gives context here), are pressure, number of moles/atoms and temperature. The temperature is going up do to the combustion process and the number of molecules is constant, therefore pressure has to rise. Pressure times and area is force, which in turn pushed the piston down creating torque. The smaller the volume the combustion gasses have to expand into, the more pressure is created to be turned into power. That means output for a given amount of fuel is higher, which means a more efficient engine.

High compression tends to make fuels ignite even without spark. For diesel engines this is what they are based on. For a petrol engine, this is bad news since they aren't designed to intentionally initiate compression ignition. With direct injection the allowable limit of compression ratios that pump fuel will support has risen. This is because the fuel isn't compressed with the incoming fresh air charge, therefore it won't suffer from compression ignition, or detonation.

High compression ratios require stronger components. This is why Diesel engines are so heavy.

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#19
In reply to #18

Re: Pressurized Fuel/Air Mixture

09/21/2021 7:33 AM

The topic was to do with an engine and not just setting alight some petrol vapors in a tin can in a classroom, and producing compression in free air. Doos.

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#20
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Re: Pressurized Fuel/Air Mixture

09/21/2021 8:05 AM

In raising the <...compression...>, one raises the temperature and vapourises the fuel, enabling it to mix with the air, creating a clean and quick explosion, as opposed to a smoky fire that goes on for a long time. Andrew Szydlo's demonstration illustrates this.

The pressure at which this takes place is determined by the properties of the fuel and the equipment in which the explosion happens.

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#21
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Re: Pressurized Fuel/Air Mixture

09/21/2021 9:10 AM

Ah Ha! So compression is important and has substance, and not as stated by yourself in your previous post.

The original post was referring to pressurizing petrol to obtain more oxygenation before burning, to improve an ignition of the fuel, to have it burn more efficiently and cleaner in a second pressurized chamber. Pressurized meaning compressed and hopefully infused with air. Yes, indeed Watson.

So we shall await the original posters result of converting his lawnmower to have a pressurized fuel delivery, as relative to a pressurized camping stove or burner.

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#16

Re: Pressurized Fuel/Air Mixture

09/20/2021 8:21 PM

This is a form of vapor carburetor

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#22

Re: Pressurized Fuel/Air Mixture

09/28/2021 4:57 PM

Would not an over rich oxygen supply cause oxidation of the metals?

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#23
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Re: Pressurized Fuel/Air Mixture

09/28/2021 5:23 PM

It would not be possible to introduce sufficient oxygen into a mixture of fuel to create oxidation on a fast scale. It would only create a better mixture for ignition and besides, in pressurising the mixture, it would contain other air born natural gases and not just oxygen.

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#24

Re: Pressurized Fuel/Air Mixture

10/01/2021 1:15 PM

With regard to atomization of a gasoline as a fuel, a couple of DIY'ers made a plexiglass carburetor and video'd it running on a single cylinder small engine.

Their Youtube video has both real-time and high speed views of the atomization of fuel as the fuel is sucked up the main jet and is atomized by the rush of air on the intake stroke. When the intake ends, droplets exit the main jet due to the inertia of the fuel flow through the jet from bowl.

Watch from 8:56 forward for about 30 seconds in the youtube video
https://www.youtube.com/watch?v=toVfvRhWbj8

I was amazed at how well the fuel atomized.

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