Heat Exchanger for Fuel Lines?
09-13-2003, 05:20 PM
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Heat Exchanger for Fuel Lines?
I read in the Mileage Enhancement thread that you guys were looking to heat up the fuel so that it atomizes better.
In my old drag racing days, I used a Cool Can which held dry ice and the aluminum fuel line wound through the can. The purpose was to cool down the feul to eliminate vapor lock, i.e. fuel atomizing before it is supposed to.
Unless the laws of physics have changed, I don't think heating the fuel is going to help at all, unless you're truckin' at the North Pole.
In my old drag racing days, I used a Cool Can which held dry ice and the aluminum fuel line wound through the can. The purpose was to cool down the feul to eliminate vapor lock, i.e. fuel atomizing before it is supposed to.
Unless the laws of physics have changed, I don't think heating the fuel is going to help at all, unless you're truckin' at the North Pole.
09-13-2003, 06:02 PM
#2
reaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaly
that all makes sense now! I couldn't agree that some schmuck came up with a magic can with a hose on it that increases efficiency. As if the engineers who have been building cars for 60 years didnt think of that and discard it already. I knew that there had to be a reason that someone didnt simply run the fuel line next to the exhaust to REALLY heat it up. Hey then you might get like 600 mpg right! NOT!
So-- the idea is to keep the fuel cool until its supposed to be used huh, great idea. Since the laws of physics dictate that a liquid of lower temperature is more dense than one of higher temperature. Then you could get more fuel into the engine if it were cooler. Hmmmmmmmmmmm--- maybe that could have been a nice ping fix from the beginning huh--makes ya wonder about a lot of things.
Tim
that all makes sense now! I couldn't agree that some schmuck came up with a magic can with a hose on it that increases efficiency. As if the engineers who have been building cars for 60 years didnt think of that and discard it already. I knew that there had to be a reason that someone didnt simply run the fuel line next to the exhaust to REALLY heat it up. Hey then you might get like 600 mpg right! NOT!
So-- the idea is to keep the fuel cool until its supposed to be used huh, great idea. Since the laws of physics dictate that a liquid of lower temperature is more dense than one of higher temperature. Then you could get more fuel into the engine if it were cooler. Hmmmmmmmmmmm--- maybe that could have been a nice ping fix from the beginning huh--makes ya wonder about a lot of things.
Tim
09-13-2003, 06:26 PM
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iirc those cans are for the carborated cars that are considerably modified, and running there pressure at aroud 7psi now we are talking about something a little different. most fuel injection will see 35-80 psi at the injector. dont know too much of the physics but i would think the vapor temp for the fuel has risen proportionatly (maybe) plus the fuel isnt vented to the atmosphere like that of a carb. not to mention that the modified cars didnt worry about the economy of the engine thats why they wanted all of the fuel they could get into the combustion chamber hence the cool cans for the gas (cold gas is dense gas)
09-13-2003, 06:42 PM
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I'm not sure how true that is but I design temperature control systems and heat exchangers for a living, and I have had a few engineers ask about controlling the fuel temp to provide better fuel economy. Of course they won't tell me exactly what they are doing.
09-13-2003, 07:40 PM
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It's similar to running a lower temp thermostat. When you switch from a the stock 192 degree thermo to the 180 degree TRD thermo, your gas mileage will go down. Why, because the temps of the fuel are cooler, along with the engine as a whole, which reduces the atomization of the fuel, which decreases gas mileage.
Chris
Chris
09-13-2003, 08:00 PM
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Let's think about this another way:
1) Hotter fuel = less dense = better gas mileage = possibly less power
2) Cooler fuel = more dense = worse gas mileage = possibly more power
Makes sens to me! And Duffdog, in reference to you comment about reducing pinging, this is the whole reason TRD came out with the cooler 180 degree thermo: to reduce pinging when supercharged!
Chris
1) Hotter fuel = less dense = better gas mileage = possibly less power
2) Cooler fuel = more dense = worse gas mileage = possibly more power
Makes sens to me! And Duffdog, in reference to you comment about reducing pinging, this is the whole reason TRD came out with the cooler 180 degree thermo: to reduce pinging when supercharged!
Chris
09-13-2003, 08:23 PM
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Congradulations on your first post. Welcome.
You are wrong about the heating fuel thing. I know for a fact it works and have done it in the past. There are several manufacturers that are infact working on fuel heaters for production vehicles. Siemens is working on a way to heat it in the fuel injector. Generally, their angle is emmissions, but increasing MPG is also a great benifit of it.
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You are wrong about the heating fuel thing. I know for a fact it works and have done it in the past. There are several manufacturers that are infact working on fuel heaters for production vehicles. Siemens is working on a way to heat it in the fuel injector. Generally, their angle is emmissions, but increasing MPG is also a great benifit of it.
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09-13-2003, 08:43 PM
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Originally posted by ravencr
Gadget, is there a point in which the fuel becomes too hot?
Chris
Gadget, is there a point in which the fuel becomes too hot?
Chris
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09-14-2003, 04:25 AM
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Engines run at higher efficiency the hotter they get....too bad the metal doesn't like to get too hot. Back in engineering school we were working on ceramic piston / sleves for exactly this reason. Gadget is quite right on heating of the fuel.....it does produce better efficiency. Remember more power does not mean more efficiency and vise versa. This is an extreemly important concept to grasp.
Drag Racers could care less about fuel mileage while power is what they are after....so the denser the fuel....the more there is.....and the more power you make. The blowers they use can deliver more air than they could possibly use (measured in psi) so fuel is the limiting factor there.
The average public does care about gas mileage so fuel atomization and engine temperature are the keys. Since it is really unsafe to run the engine above the current temperatures we run at today (all automakers have done significant testing in this area already to maximize this) then the only thing to work on is fuel atomization.....this is what people were talking about with the heating of the fuel before injection.
Chris, I don't suggest heating the fuel past the boiling point either.
PS This is also why changing the thermostat changes the power AND fuel economy.
Drag Racers could care less about fuel mileage while power is what they are after....so the denser the fuel....the more there is.....and the more power you make. The blowers they use can deliver more air than they could possibly use (measured in psi) so fuel is the limiting factor there.
The average public does care about gas mileage so fuel atomization and engine temperature are the keys. Since it is really unsafe to run the engine above the current temperatures we run at today (all automakers have done significant testing in this area already to maximize this) then the only thing to work on is fuel atomization.....this is what people were talking about with the heating of the fuel before injection.
Chris, I don't suggest heating the fuel past the boiling point either.
PS This is also why changing the thermostat changes the power AND fuel economy.
Last edited by MTL_4runner; 09-14-2003 at 05:39 AM.
09-14-2003, 11:46 AM
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Purely Theoretical
I have no real world experience to back this up.
OK, with that out of the way. Here's how I see it. You want the fuel to be as hot as possible in the line under pressure without vaporizing. Since it IS under pressure in the line, the boiling point is higher than at atmospheric pressure. Then, when the fuel comes out of the line, the reduced pressure will cause it to instantly boil (vaporize), increasing dispersion and shrinking particle size, which in turn results in a more complete burn. The problem as I see it is making sure that the fuel does not vaporize in the line. This will require some kind of control system and thermostat to get up to the right temps (depending on fuel line pressure) and could be tough to engineer, depending on how much the variables change (flow rate, line pressure, temp). The idea IS sound so long as there is ANY unburned fuel after the cylinder, there is room for improvement. And in most engines, there is some fuel that exits the cylinder unburned - I can guarantee there's some in my 3.slow.
Disclaimer: Yes, I am a mechanical engineer, so everything I say is probably out of whack.
OK, with that out of the way. Here's how I see it. You want the fuel to be as hot as possible in the line under pressure without vaporizing. Since it IS under pressure in the line, the boiling point is higher than at atmospheric pressure. Then, when the fuel comes out of the line, the reduced pressure will cause it to instantly boil (vaporize), increasing dispersion and shrinking particle size, which in turn results in a more complete burn. The problem as I see it is making sure that the fuel does not vaporize in the line. This will require some kind of control system and thermostat to get up to the right temps (depending on fuel line pressure) and could be tough to engineer, depending on how much the variables change (flow rate, line pressure, temp). The idea IS sound so long as there is ANY unburned fuel after the cylinder, there is room for improvement. And in most engines, there is some fuel that exits the cylinder unburned - I can guarantee there's some in my 3.slow.
Disclaimer: Yes, I am a mechanical engineer, so everything I say is probably out of whack.
09-16-2003, 04:32 AM
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Originally posted by instigator
hey gadget, when are we gonna get the write up on your heat exchanger?
hey gadget, when are we gonna get the write up on your heat exchanger?
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09-16-2003, 04:33 AM
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What's up with that Gadget! You don't want to start sounding like Steve do ya? Just kidding! But, is it real easy to do or a reason you don't want to?
Chris
Chris
09-16-2003, 04:57 AM
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09-16-2003, 06:24 AM
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well its not like i cant devise my own, i mean i do work as a mech in one of atl largest airlines and the 3rd largest in the world. i do have resources, thanks big G for your..... whatever
Last edited by instigator; 09-16-2003 at 06:25 AM.
09-16-2003, 10:50 PM
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Originally posted by instigator
hey gadget, when are we gonna get the write up on your heat exchanger?
hey gadget, when are we gonna get the write up on your heat exchanger?
Try this:
Originally posted by instigator
Gadget-
Would you be willing to share your ideas or research on a heat exchanger? I would greatly appreciate any pointers or suggestions. Thank you!
Gadget-
Would you be willing to share your ideas or research on a heat exchanger? I would greatly appreciate any pointers or suggestions. Thank you!
Last edited by HaveBlue; 09-16-2003 at 11:10 PM.
09-17-2003, 04:28 AM
#20
Re: Purely Theoretical
Originally posted by mcsherbs
Since it IS under pressure in the line, the boiling point is higher than at atmospheric pressure.
Since it IS under pressure in the line, the boiling point is higher than at atmospheric pressure.
Then, when the fuel comes out of the line, the reduced pressure will cause it to instantly boil (vaporize), increasing dispersion and shrinking particle size, which in turn results in a more complete burn.
good luck guys...
