fuel "boiling"
10-20-2007, 06:00 PM
#21
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... Hey I took my thermodynamics course last year and got an A!!! I know the ideal gas law forwards, backwards, thermal energy, heat, adiabats, isotherms, isochors, blah blah blah... 
But, uhh. Its not the LIQUID water that is increasing in temperature, it is the steam. With your analogy, you can say with an extremely large pressure, water would not turn to steam at 400*C? Maybe I am just misinterpreting your point.
I know that a higher pressure will equate to a higher temperature, I just don't think that the boiling point (at which an element or compound like water) would be changed because of that. A pressure cooker uses the pressure of the steam and not the water.
But, uhh. Its not the LIQUID water that is increasing in temperature, it is the steam. With your analogy, you can say with an extremely large pressure, water would not turn to steam at 400*C? Maybe I am just misinterpreting your point.
I know that a higher pressure will equate to a higher temperature, I just don't think that the boiling point (at which an element or compound like water) would be changed because of that. A pressure cooker uses the pressure of the steam and not the water.
10-20-2007, 08:03 PM
#22
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So you don't think the boiling pt of a liquid varies with pressure? Dude you're missing an important fundamental in chemistry. Here's some homework for you. The boiling pt of water at sea level is 212 degrees F, what is the boiling pt at 7000 ft above sea level? Assume an average atmospheric pressure for each elevation.
Last edited by mt_goat; 10-20-2007 at 08:18 PM.
10-20-2007, 08:40 PM
#23
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Got a better one whats the boiling point of water used in a US Navy Submarine Nuclear Reactor. Try around 900+ degrees F. Why doesnt the water boil till this point cause its pressurized, look up pressurized Nuclear reactors.
10-20-2007, 09:36 PM
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... Hey I took my thermodynamics course last year and got an A!!! I know the ideal gas law forwards, backwards, thermal energy, heat, adiabats, isotherms, isochors, blah blah blah...
But, uhh. Its not the LIQUID water that is increasing in temperature, it is the steam. With your analogy, you can say with an extremely large pressure, water would not turn to steam at 400*C? Maybe I am just misinterpreting your point.
I know that a higher pressure will equate to a higher temperature, I just don't think that the boiling point (at which an element or compound like water) would be changed because of that. A pressure cooker uses the pressure of the steam and not the water.
But, uhh. Its not the LIQUID water that is increasing in temperature, it is the steam. With your analogy, you can say with an extremely large pressure, water would not turn to steam at 400*C? Maybe I am just misinterpreting your point.
I know that a higher pressure will equate to a higher temperature, I just don't think that the boiling point (at which an element or compound like water) would be changed because of that. A pressure cooker uses the pressure of the steam and not the water.
I tried not to learn this stuff, but 2 1/2 years of chem and a year of physics drove it deep into my brain
I'm a chiropractor - I just wanted to pop people.
10-21-2007, 06:31 AM
#25
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No, I see what you are talking about 4biker in your last post.... I was imagining a different process. Closed system, equals a totally different... Uhh... outcome.
I was just reading too fast, listening to metal, and shooting herion at the same time to understand what was going on...
Last edited by BajaRunner; 10-21-2007 at 06:34 AM.
11-02-2007, 05:44 PM
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I have seen gasoline boil before. I once had a 5 gal steel military style gas can setting too close to a generator I was running. The generator ran out of fuel and as I opened the hot gas can a lot of pressure started venting and the can sides bulged as the gas started to boil, then the pressure in the can increased enough to stop the boiling. Then the venting released enough pressure it started boiling again, this cycle repeated 5 or 6 times as I was running away. I think that was one of my 9 lives used up.
My guess is your fuel is going through the fuel pump and high-pressure fuel line to your regulator on top of the engine where along the way it is picking up a lot of heat from an engine that is borderline overheating but your temp gauge doesn't show it because... well Toyota doesn't want you to worry about your coolant temp until it reaches about 240 F, where at that point the temp gauge starts to move from the center of the normal range...then the fuel that isn't needed for the fuel rail is returned to the fuel tank by the low pressure fuel return line. It is my guess that along this low pressure line trip back to the fuel tank that would be the most likely place for the gas to boil, especially after shuting down the cooling system and heatsoak has a chance to bake those fuel lines sitting on top of the engine. As the gas boils the pressure would just be released into the gas tank via the return line kind of like a kid blowing bubbles into a drink through a straw.
My guess is your fuel is going through the fuel pump and high-pressure fuel line to your regulator on top of the engine where along the way it is picking up a lot of heat from an engine that is borderline overheating but your temp gauge doesn't show it because... well Toyota doesn't want you to worry about your coolant temp until it reaches about 240 F, where at that point the temp gauge starts to move from the center of the normal range...then the fuel that isn't needed for the fuel rail is returned to the fuel tank by the low pressure fuel return line. It is my guess that along this low pressure line trip back to the fuel tank that would be the most likely place for the gas to boil, especially after shuting down the cooling system and heatsoak has a chance to bake those fuel lines sitting on top of the engine. As the gas boils the pressure would just be released into the gas tank via the return line kind of like a kid blowing bubbles into a drink through a straw.
I just got back from a week long trip to Mammoth Lakes, CA. The temps were in the 40's and the elevation about 8000ft. When I would remove my gas cap to top off the tank, I got the familiar hiss but no boiling/bubbling. I assume, of course, that I won't hear it again till summer.
Here's a pic from the trip, by the way:
Last edited by patin22; 11-02-2007 at 11:19 PM.
11-03-2007, 07:31 AM
#28
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That's pretty much what it sounds like. Is this something I should have looked at before the summer months. Is it a relatively normal occurrence due to the extreme temps? Could something damaged or not working properly? If it is normal, I have no problem with the noise. I just want to make sure that I'm not driving around a potentially explosive situation! lol
I just got back from a week long trip to Mammoth Lakes, CA. The temps were in the 40's and the elevation about 8000ft. When I would remove my gas cap to top off the tank, I got the familiar hiss but no boiling/bubbling. I assume, of course, that I won't hear it again till summer.
I just got back from a week long trip to Mammoth Lakes, CA. The temps were in the 40's and the elevation about 8000ft. When I would remove my gas cap to top off the tank, I got the familiar hiss but no boiling/bubbling. I assume, of course, that I won't hear it again till summer.
Maybe post some pics from under the hood, maybe something will jump out as unusual, especially of the "cold air" intake.
Last edited by mt_goat; 11-03-2007 at 07:37 AM.
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