neubie need engine size explanations
09-01-2003, 10:43 PM
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neubie need engine size explanations
I am not an engineer but place a drop
of anything flamable on something else that is glowing redhot. What happens?
It ignites of course.
Ron
of anything flamable on something else that is glowing redhot. What happens?
It ignites of course.
Ron
09-02-2003, 12:53 PM
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neubie need engine size explanations
Yesterday afternoon, I set up my small chem lab in my garage and performed a few experiments with hobby fuel (methanol, nitro methane, natural castor, synthetic castor, & additives), platinum coil (ruined a few glow plugs before successfully extracting a coil). The coil was attached to a piece of aluminum wire (aluminum was selected it oxidizes quickly and becomes an insulator and should not impact the experiment).
I brought the fuel (in a glass flask) to a temperature of around 60 degrees C by submersing it in a pot of water (a hot plate was used to keep the water temperature consistent). This was done to promote evaporation of the methanol (needs to be in a gaseous state to burn).
I introduced the platinum coil to the methanol vapor with no reaction.
I heated the coil using a lit candle until it was red hot. While behind my lexan shield (just in case the flask exploded), I put the heated coil into the flask about an inch from the liquid fuel. By the time the coil was in the flask, it was no longer glowing (but still very hot). The coil became hotter as evidenced by it beginning to glow. The vapor ignited with a flame shooting out the top of the flask. The coil was no longer glowing. Within a second or two, the coil started to glow and the process started over again.
I redid this experiment with copper wire in place of the platinum. I found that it reacted in much the same way until the copper had completely oxidized.
My conclusions - The heat in the coil (hot but not glowing) was sufficient for the air/fuel mixture in contact with the coil to burn (methanol burns with an invisible flame in daylight) generating some heat. This in turn heat the coil. The additional heat is sufficient to burn more of the air fuel mixture making the coil hotter. Eventually, there is enough heat generated to cause all the vapor to ignite.
My observations imply that:
The heated platinum coil provides localized heat to allow the methanol and oxygen to react (or combust). The absorption/radiation properties (along with a low propensity to oxidize), help the continuous (and escalating) burn of the fuel mixture.
I observed the platinum playing a passive role (with respect to storing and releasing heat energy). Working in my garage, it is impossible to discern whether or not the platinum was an active catalyst (whether or not it temporarily reacted forming a molecule to react again braking the molecular bond and returning to platinum).
--------------
My previous explanations were incomplete (hence inaccurate) and did not include the complex localized burn that takes place at the coil which generates sufficient heat for the fuel charge to ignite.
I brought the fuel (in a glass flask) to a temperature of around 60 degrees C by submersing it in a pot of water (a hot plate was used to keep the water temperature consistent). This was done to promote evaporation of the methanol (needs to be in a gaseous state to burn).
I introduced the platinum coil to the methanol vapor with no reaction.
I heated the coil using a lit candle until it was red hot. While behind my lexan shield (just in case the flask exploded), I put the heated coil into the flask about an inch from the liquid fuel. By the time the coil was in the flask, it was no longer glowing (but still very hot). The coil became hotter as evidenced by it beginning to glow. The vapor ignited with a flame shooting out the top of the flask. The coil was no longer glowing. Within a second or two, the coil started to glow and the process started over again.
I redid this experiment with copper wire in place of the platinum. I found that it reacted in much the same way until the copper had completely oxidized.
My conclusions - The heat in the coil (hot but not glowing) was sufficient for the air/fuel mixture in contact with the coil to burn (methanol burns with an invisible flame in daylight) generating some heat. This in turn heat the coil. The additional heat is sufficient to burn more of the air fuel mixture making the coil hotter. Eventually, there is enough heat generated to cause all the vapor to ignite.
My observations imply that:
The heated platinum coil provides localized heat to allow the methanol and oxygen to react (or combust). The absorption/radiation properties (along with a low propensity to oxidize), help the continuous (and escalating) burn of the fuel mixture.
I observed the platinum playing a passive role (with respect to storing and releasing heat energy). Working in my garage, it is impossible to discern whether or not the platinum was an active catalyst (whether or not it temporarily reacted forming a molecule to react again braking the molecular bond and returning to platinum).
--------------
My previous explanations were incomplete (hence inaccurate) and did not include the complex localized burn that takes place at the coil which generates sufficient heat for the fuel charge to ignite.
09-02-2003, 03:37 PM
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neubie need engine size explanations
My little experiment showed me that halb0971 is correct in there is a "catalytic action" of the platinum coil in a glow plug, but not necessarily in the suspected manner. Having played with fire (litterally), I hope we all have a little better understanding of how it works (I've even got a few new ideas on how to build a simple pulse jet engine for r/c - I just hope I don't blow myself up first).
09-02-2003, 09:33 PM
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neubie need engine size explanations
Originally posted by i8tweety
My little experiment showed me that halb0971 is correct in there is a "catalytic action" of the platinum coil in a glow plug, but not necessarily in the suspected manner. Having played with fire (litterally), I hope we all have a little better understanding of how it works (I've even got a few new ideas on how to build a simple pulse jet engine for r/c - I just hope I don't blow myself up first).
My little experiment showed me that halb0971 is correct in there is a "catalytic action" of the platinum coil in a glow plug, but not necessarily in the suspected manner. Having played with fire (litterally), I hope we all have a little better understanding of how it works (I've even got a few new ideas on how to build a simple pulse jet engine for r/c - I just hope I don't blow myself up first).
Very interesting.
One other thing to consider in your pondering over your experiment though, it was performed at ambient pressure, although at an elevated temp. Also in the engine we are not dealing with liquid, we are dealing with gasses, which you attempted to simulate with temperature. Very interesting to see that all the engine/ glow plug/ fuel manufacturers were correct in at least a simplistic explanation of how the methanol ignites, and the glow plug stays litIt still makes one wonder though why top fuel dragsters who run methanol do not run a glow ignition instead of a typical electronic ignition to save a few more pounds. I guess they would rather sacrifice the precision for the weight.
Sean
09-03-2003, 01:57 AM
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neubie need engine size explanations
Actually, I was dealing with a vapor, not a liquid. The heated coil was suspended above the liquid.
It's an interesting question with respect to the top fuel dragsters. With the high compression ratios and the desire to adjust ignition timing depending on conditions, I think the tuning disadvantages would outweigh the weight savings. Then again, I've been wrong before.
It's an interesting question with respect to the top fuel dragsters. With the high compression ratios and the desire to adjust ignition timing depending on conditions, I think the tuning disadvantages would outweigh the weight savings. Then again, I've been wrong before.
09-03-2003, 10:11 AM
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neubie need engine size explanations
Originally posted by i8tweety
Actually, I was dealing with a vapor, not a liquid. The heated coil was suspended above the liquid.
It's an interesting question with respect to the top fuel dragsters. With the high compression ratios and the desire to adjust ignition timing depending on conditions, I think the tuning disadvantages would outweigh the weight savings. Then again, I've been wrong before.
Actually, I was dealing with a vapor, not a liquid. The heated coil was suspended above the liquid.
It's an interesting question with respect to the top fuel dragsters. With the high compression ratios and the desire to adjust ignition timing depending on conditions, I think the tuning disadvantages would outweigh the weight savings. Then again, I've been wrong before.
Right, as I said you simulated the vapor, via the temp increase, I was just pointing out that although your test conditions were close, there were still some other variable not accounted for. Just on a purely scientific aspect though, isn’t the phase change vapor form of the fuel going to react differently than the misted liquid particles in air of the fuel? My chemistry education was not all that extensive, and a few years behind me so my memory is getting foggy. I realize the intent is to induce a vapor into the cylinder and compress it, but that vapor is not actually a phase changed vapor is it, or at least not completely? In which case I think you experiment might be a little easier to combust. I'm not sure.
I agree on the Top Fuel engines, i mean when you are putting out 8,000 hp what’s a 5 pounds or so.
Sean
09-03-2003, 10:21 AM
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neubie need engine size explanations
and you lacked compression too which helps cause the catalytic reaction
compression causes heat by itself and by compressing the gas inside the cylinder in close contact with the platinium wire it causes combustion. otherwise they would use copper or some other wire to do the same job
compression causes heat by itself and by compressing the gas inside the cylinder in close contact with the platinium wire it causes combustion. otherwise they would use copper or some other wire to do the same job
09-03-2003, 08:46 PM
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neubie need engine size explanations
I used copper wire in my experiment as well. It worked for a short period of time, but it oxidized quickly and the chain reaction stopped.
As for compression to cause the chain reaction (repeated burn cycles), it didn't need it. I do agree that it is needed in a hobby engine as it is required to help regulate engine timing.
As for compression to cause the chain reaction (repeated burn cycles), it didn't need it. I do agree that it is needed in a hobby engine as it is required to help regulate engine timing.
09-04-2003, 12:01 AM
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controled combustion
The thing that is missing is a car engine with high compression is VERY sensitive to timing advance. detonation will take out a top fuel engine in a 1/2 second.
with a glow engine there is no way to "time" when the fuel ignites. how do you set it to ignite at lets say 20 degrees before TDC?
Also isn't the cyl wall an upside down icecream cone?
if so then the compression comes up all of a sudden at the top of the stroke. Maybe this is how a glow eng "adjusts" timing
with a glow engine there is no way to "time" when the fuel ignites. how do you set it to ignite at lets say 20 degrees before TDC?
Also isn't the cyl wall an upside down icecream cone?
if so then the compression comes up all of a sudden at the top of the stroke. Maybe this is how a glow eng "adjusts" timing
09-04-2003, 01:28 AM
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neubie need engine size explanations
yes it is, they controll the "spark" by the compression. more compression fires sooner so you cut the amount of nitro to compensate and vice versa
john
john
09-04-2003, 09:48 AM
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Re: Oh yeah
Originally posted by avoor1
.18 is cubic inches. 3.0 is cubic centimeters. Right? A .18 cubic inch is a 3.0 cubic centimeter motor.
.18 is cubic inches. 3.0 is cubic centimeters. Right? A .18 cubic inch is a 3.0 cubic centimeter motor.
Yes
.18 ci = 2.949 cc
Sean
09-04-2003, 10:47 AM
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neubie need engine size explanations
Originally posted by halb0971
Just on a purely scientific aspect though, isn’t the phase change vapor form of the fuel going to react differently than the misted liquid particles in air of the fuel? My chemistry education was not all that extensive, and a few years behind me so my memory is getting foggy. I realize the intent is to induce a vapor into the cylinder and compress it, but that vapor is not actually a phase changed vapor is it, or at least not completely? In which case I think you experiment might be a little easier to combust. I'm not sure.
Just on a purely scientific aspect though, isn’t the phase change vapor form of the fuel going to react differently than the misted liquid particles in air of the fuel? My chemistry education was not all that extensive, and a few years behind me so my memory is getting foggy. I realize the intent is to induce a vapor into the cylinder and compress it, but that vapor is not actually a phase changed vapor is it, or at least not completely? In which case I think you experiment might be a little easier to combust. I'm not sure.
My personal opinion with respect to compression is that it may expedite the process, but it doesn't create it. Compression is being used to change the conditions to precipitate the charge igniting at a desired time. I base this on the fact I can create a continuous cycle of evaporation (air fuel mixing in "combustion flask"), ignition, combustion chamber cooling (vaccuum pulling in fresh air), evaporation, combustion,..... Without controlling pressure, I cannot dictate exactly when this will happen (by changing the rate of evaporation, I suppose I could have some control).
This has turned into a great discussion! I might just have to add a link to it in the engine forum. They don't know what they are missing.
09-04-2003, 11:08 AM
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neubie need engine size explanations
Being an engineer and thinking about stuff like this on this kind of level makes one wonder what normal people think about all day long, doesn't it?
Sean
Sean
09-04-2003, 11:20 AM
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neubie need engine size explanations
It certainly is nice to exercise the brain once in a while.
I'm still looking for supporting documentation (or experiments) for platinum (or other similar metals) acting as a catalyst in the reaction (burn). It's hard to see electron transfer (or even chemical bonds for that matter) in my garage!
I'm still looking for supporting documentation (or experiments) for platinum (or other similar metals) acting as a catalyst in the reaction (burn). It's hard to see electron transfer (or even chemical bonds for that matter) in my garage!
09-04-2003, 12:11 PM
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neubie need engine size explanations
LOL you don't have an electron microscope handy to watch the combustion reaction with.
I am just looking forward to getting my garage added on in the near future and getting my hobby room done.
I am just looking forward to getting my garage added on in the near future and getting my hobby room done.
09-04-2003, 01:20 PM
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Your giving us to much credit!
Originally posted by halb0971
Being an engineer and thinking about stuff like this on this kind of level makes one wonder what normal people think about all day long, doesn't it?
Sean
Being an engineer and thinking about stuff like this on this kind of level makes one wonder what normal people think about all day long, doesn't it?
Sean
09-04-2003, 02:46 PM
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neubie need engine size explanations
Originally posted by halb0971
Being an engineer and thinking about stuff like this on this kind of level makes one wonder what normal people think about all day long, doesn't it?
Sean
Being an engineer and thinking about stuff like this on this kind of level makes one wonder what normal people think about all day long, doesn't it?
Sean
09-04-2003, 03:55 PM
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neubie need engine size explanations
Originally posted by RCFreakInFL
Isn't it the technicians that do the "work".....but the engineers that take all the credit
Isn't it the technicians that do the "work".....but the engineers that take all the credit
I wasn't attempting to take credit for anything, just pondering what normal people do all day. Sometimes it sucks being an enginerd, I mean engineer.
But to your comment, I have been on both sides of this argument, and yes there are extremes in any situation, but it has been my experience that the good engineers take credit where credit is due and address credit to those that deserve it. Which makes everything better.
Sean
09-04-2003, 05:58 PM
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neubie need engine size explanations
Originally posted by halb0971
I wasn't attempting to take credit for anything, just pondering what normal people do all day. Sometimes it sucks being an enginerd, I mean engineer.
But to your comment, I have been on both sides of this argument, and yes there are extremes in any situation, but it has been my experience that the good engineers take credit where credit is due and address credit to those that deserve it. Which makes everything better.
Sean
I wasn't attempting to take credit for anything, just pondering what normal people do all day. Sometimes it sucks being an enginerd, I mean engineer.
But to your comment, I have been on both sides of this argument, and yes there are extremes in any situation, but it has been my experience that the good engineers take credit where credit is due and address credit to those that deserve it. Which makes everything better.
Sean
