-   DIY / How-to (
-   -   why do we burn gasoline so foolishly? (

peterrr 07-18-2014 12:51 PM

why do we burn gasoline so foolishly?
Because most tinkerers haven't the slightest idea about partial pressures I wrote this theory. Look in the last part for the tinkerer advice

gone-ot 07-18-2014 02:49 PM

...because playing around with hydrazine is dangerous to life & limb.

aerohead 07-18-2014 06:17 PM

We had unsymmetricaldimethylhydrazine rocket fuel at Edwards Air Force base and I was told that we were very fortunate to never have had to dispense any of it in the 30-months I was there.:o

gone-ot 07-18-2014 08:57 PM

During WWII the Germans used it in both aircraft and missiles...sometimes with BOOM results. It's considered a hypergolic fuel.

peterrr 07-19-2014 02:57 AM

Thank you for your concerns about the formed chemicals. Hydrazines are reputedly unstable, but they are used with far less C atoms than this. Nitrates are also used in explosives (diesel fertilizer bomb) but the formed nitrate molecule has far less N atoms in it. If anyone would know the formation enthalpies for these big molecules it would be greatly appreciated. As for tinkering your only concern is the condensing fuel. By the way treating the cylinder with steam would also work for diesels, they condense even more fuel due to the fact diesel has a high boiling point. (And you would have guessed that by looking at the soot that comes out)

peterrr 07-19-2014 04:01 AM

steam converter
I found a nice picture of an LPG vaporizer using exhaust heat at Cats citroen It boils LPG with the vaporizer on the exhaust .

2000mc 07-19-2014 04:36 AM

Sorry, what temperature do you figure fuel is condensing at? 100C like the coolant temperature? But then use the pressure of the compresion, and ignore the temperature the compresion creates?

peterrr 07-19-2014 05:32 AM

The example given is only to demonstrate how you could make use of the exhaust heat to boil and make steam of water. In this 2CV they boil liquid LPG in this thing so they have gas at sufficient pressure. And I thought it would give you an idea of how something like that would look like. (mostly it is better to steal idea's than to come up with your own rubbish and this works so..... why not use as an example for a steam converter?)

2000mc 07-19-2014 11:24 AM

I thought a lot of this was trying to fix an issue about fuel condensing.

What temperture do you figure fuel is condensing?

peterrr 07-19-2014 12:02 PM

pressures an temperatures
The temperature is kind of unknown because we don't know the inside temperature of the cylinder head. But we do know the temperature of the coolant (its a dial on the dashboard) and it is kept mostly at 80-85 C(and this varies a bit per engine type). However if you really step on it (you will have to transport a lot of heat from inside to outside) there will be a difference between the inside (which is heated) and the outside (which is cooled). My guess for the inside temperature when you really step on it constantly(going up a hill) would be 100C. But when you are accelerating and the water pump still turns slowly and the thermostats is still closed I guess it could run up to 110C.
The pressure at which the fuel condensates will vary with the temperature. The condensation pressure is something like P= 10Power(a/T). The boiling point of septane is about the same as water so as a first guess you could look the pressures for 80 100 and 110C up in a steam table. And once you've done that fill it in in the Raoult law sum.
However the car will enrich the fuel (with a acceleration pump) and with an enrichment formula for heavy loads. So you could take the condensation pressure of the fuel constant. The water vapour pressure would vary.

All times are GMT -4. The time now is 06:33 AM.

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright