Login    Register
User Information
Username:
Password:
We are a free and open
community, all are welcome.
Click here to Register
Sponsored
Who is online

In total there are 49 users online :: 5 registered, 0 hidden and 44 guests


Most users ever online was 155 on Mon Aug 15, 2016 1:40 am

Registered users: Bing [Bot], Google [Bot], Google Adsense [Bot], MSNbot Media, Yahoo [Bot] based on users active over the past 5 minutes

The Team
Administrators
Global Moderators
global_moderators.png CS

Gasoline stochiometric mixture.

Post questions and info about hybrid (compressed gas with fuel) powered cannons here. This includes discussion about fuels, ratios, ignition systems, build types, safety, and anything else relevant.
Sponsored 
  • Author
    Message

Gasoline stochiometric mixture.

Unread postAuthor: Necrosis » Sat Mar 22, 2008 8:19 pm

What is the perfect mix of air and gasoline in percentage of gasoline for the given volume?

I found that a ratio of 14:1 was best or something.. but this does not ring a bell.
14 parts of air for 1 part of gasoline?

I don't know..

I'm probably going to build a hybrid sometime this week, wish me luck. :oops:

And thanks in advanced!
  • 0

Allthough we may be the most intelligent creature on this planet, we are also the most inconsistent.
To find peace within our existence we often create a logic that endangers our lives.
User avatar
Necrosis
2nd Lieutenant
2nd Lieutenant
 
Posts: 239
Joined: Tue Jul 03, 2007 10:03 am
Reputation: 0

Unread postAuthor: LikimysCrotchus5 » Sat Mar 22, 2008 8:25 pm

Lets see if i can be jimmy. (I know stoichiometry too, let me just find the formula for gasoline or whatever you call it.)

Well i found out that its common chemical formula is C8H18. So my stoichiometry will be based on that.

combustion is: 2C8H18 + 25O2 = 16CO2 + 18H2O.

So gasoline to oxygen ratio is 2:25 or .08.

Now since 20.95% of the earth's atmosphere is oxygen, you need to multiply that by gasoline/oxygen ratio, .2095*.08 = .01676 or 1.676%

So that percentage should be the amount of gasoline in the chamber, correct me if im wrong jimmy.

EDIT: But yea gasoline is a bunch of hydrocarbons, what i found out from 5 min of research, so this ratio may not be right because your gas may not be C8H18.
  • 0

Last edited by LikimysCrotchus5 on Sat Mar 22, 2008 8:48 pm, edited 2 times in total.
4SPC, My 4" piston 3" porting cannon
Memo:
Fix up copper cannon
Fix up 4SPC
Start Stirrup pump
Start Toolies piston bazooka
User avatar
LikimysCrotchus5
Brigadier General
Brigadier General
 
Posts: 1100
Joined: Tue Sep 04, 2007 10:16 pm
Reputation: 0

Unread postAuthor: DYI » Sat Mar 22, 2008 8:28 pm

Gasoline is composed of a LOT of different hydrocarbons. Doing stoichiometry for it is a whole different beast compared to things like air/propane. Considering how widely used gasoline combustion is, you should be able to find numbers somewhere.
  • 0

Spudfiles' resident expert on all things that sail through the air at improbable speeds, trailing an incandescent wake of ionized air, dissociated polymers and metal oxides.
User avatar
DYI
Lieutenant General
Lieutenant General
 
Posts: 2861
Joined: Sat Jul 07, 2007 8:18 pm
Location: The People's Republic of Canuckistan
Country: Turks and Caicos Islands (tc)
Reputation: 9

Unread postAuthor: mark.f » Sat Mar 22, 2008 8:56 pm

The stoichiometric ratio commonly quoted is 14.7% gasoline to air (mass). At least, that's the base mixture used for engines before optimization.
  • 0

User avatar
mark.f
Donating Member
Donating Member
 
Posts: 3464
Joined: Sat May 06, 2006 11:18 am
Country: United States (us)
Reputation: 21

Unread postAuthor: jimmy101 » Sun Mar 23, 2008 12:17 pm

LikimysCrotchus5 hit it dead on. The stoichimotric ratio for gasoline in air is about ~1.7 mole percent. If the gasoline is vaporized then the mole percent is the same as the volume percent. I suspect that if you convert markfh11q 14.7 wht. percent into mole percent you'll get ~1.7.

Gasoline is a mixture of a bunch of stuff but the vast majority has the same, or nearly the same, chemical formula (but not chemical structure) as octane. You can go through the calc's with hexane, heptane, octane, iso-octane, nanane (sp?) and you'll find they are all very similar so it really doesn't matter too much. Other things introduce much larger errors than the uncertainty in the exact chemical composition.

The tricky part is measuring the correct amount of a liquid fuel since the volume of the liquid is so much less than the volume of the gas. According to my "liquid fuels" page a 100in<sup>3</sup> chamber takes 0.184mL of gasoline for a stoichiometric mix with air. (Notice how I mix english and metric units to keep folks on their toes :roll: ) That is something in the vicinity of 2 drops liquid gasoline for the 100ci chamber.

Since it is very difficult to measure 2 drops with any kind of accuracy, especially since the high vapor pressure of the gas makes it piddle out of an eyedropper, the exact stoichiometry is the least of your worries.
  • 0

Image

jimmy101
Lieutenant General
Lieutenant General
 
Posts: 3129
Joined: Wed Mar 28, 2007 9:48 am
Location: Greenwood, Indiana
Country: United States (us)
Reputation: 7

Unread postAuthor: LikimysCrotchus5 » Sun Mar 23, 2008 12:23 pm

jimmy101 wrote:LikimysCrotchus5 hit it dead on


thank you, so i know i was right.

I guess chem class really was useful. I though i might give you a break ne way, you do way to many calculations a day :D .
  • 0

4SPC, My 4" piston 3" porting cannon
Memo:
Fix up copper cannon
Fix up 4SPC
Start Stirrup pump
Start Toolies piston bazooka
User avatar
LikimysCrotchus5
Brigadier General
Brigadier General
 
Posts: 1100
Joined: Tue Sep 04, 2007 10:16 pm
Reputation: 0

Unread postAuthor: Necrosis » Sun Mar 23, 2008 3:13 pm

My mom uses really tiny syringes for her reuma, I figured i'd use those.. but.. that's a really tiny amount.

I might just use a buthane lighter and stuff now, thanks a lot!
  • 0

Allthough we may be the most intelligent creature on this planet, we are also the most inconsistent.
To find peace within our existence we often create a logic that endangers our lives.
User avatar
Necrosis
2nd Lieutenant
2nd Lieutenant
 
Posts: 239
Joined: Tue Jul 03, 2007 10:03 am
Reputation: 0

Sponsored

Sponsor
 


Return to Hybrid Cannon Discussion

Who is online

Registered users: Bing [Bot], Google [Bot], Google Adsense [Bot], MSNbot Media, Yahoo [Bot]

Reputation System ©'