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 :: 4 registered, 0 hidden and 45 guests


Most users ever online was 218 on Wed Dec 07, 2016 6:58 pm

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

The Team
Administrators
Global Moderators
global_moderators.png CS

Iso Octane Fuel

All non-spudgun related discussion goes here such as projects, theories, serious questions, etc. All "off-topic" posts (aka useless posting, determined by moderators) will be removed.
Sponsored 
  • Author
    Message

Iso Octane Fuel

Unread postAuthor: rcman50166 » Thu Oct 29, 2009 10:50 am

Hey I can't figure out the theoretical flow rate of Isooctane fuel through a small engine. I keep getting numbers on the order of 4 L/min. It's ridiculously high and I don't know how I keep getting it. I'm basing the ratios off of the stoichiometric ratio of fuel to air. 12.5O2+C8H18->9H20+8CO2. Attached I have an excel sheet containing all of the calculations and figures I've used to get my answer. Maybe one of you can help me?
  • 0

Attachments
Engine Balance2.zip
Here is the file. I'm reasonably sure everything is correct.
(14.52 KiB) Downloaded 41 times
Image
User avatar
rcman50166
Colonel
Colonel
 
Posts: 697
Joined: Sat Jan 19, 2008 7:11 pm
Location: Bethel, CT
Reputation: 0

Unread postAuthor: Technician1002 » Thu Oct 29, 2009 11:35 am

Must be using the new version of Office. I can't open the file. Can you save it in an older format such as office 97 or 2K?
  • 0

User avatar
Technician1002
Chief of Staff
Chief of Staff
 
Posts: 5190
Joined: Sat Apr 04, 2009 11:10 am
Reputation: 14

Unread postAuthor: rcman50166 » Thu Oct 29, 2009 4:12 pm

Technician1002 wrote:Must be using the new version of Office. I can't open the file. Can you save it in an older format such as office 97 or 2K?


Here ya go
  • 0

Attachments
Engine Balance2 (2).zip
(10.49 KiB) Downloaded 39 times
Image
User avatar
rcman50166
Colonel
Colonel
 
Posts: 697
Joined: Sat Jan 19, 2008 7:11 pm
Location: Bethel, CT
Reputation: 0

Unread postAuthor: psycix » Fri Oct 30, 2009 6:18 am

You are calculating it by multiplying the intake consumption with the volumetric fraction (why are you dividing it by two?!), that seems okay.
This indeed yields 4,3 (or 8,7 when not divided by two).

This is the volume of gaseous fuel that passes the engine in one minute.
I don't get why you are dividing by two so I'll work with 8,7 from now on.

Divide the volume by the molar gas constant:
8,781295781/24,12941111=0,363924993 mol
This is the number of mol of fuel that passes in one minute.

Multiply this by the molar mass:
0,363924993*114,2656=41,58410773 g
This is the mass of the amount of fuel that passes in one minute.

Density of liquid: 688 kg/m^3
Divide by 1000 and then by the density.
(41,58410773/1000)/688=6,0442E-05 m^3
This is the volume of the liquid fuel that passes in one minute.

Multiply by 10^6 to convert m^3 into cm^3:
60,44201705 cm^3 (or mL, or cc) per minute!

So it consumes about 1 cc of liquid fuel per second.
Feel free correct me if I'm wrong, but I think this is it.
  • 0

Till the day I'm dieing, I'll keep them spuddies flying, 'cause I can!

Spudfiles steam group, join!
User avatar
psycix
Donating Member
Donating Member
 
Posts: 3684
Joined: Mon Jun 25, 2007 7:12 am
Location: The Netherlands
Reputation: 0

Unread postAuthor: rcman50166 » Fri Oct 30, 2009 7:35 am

psycix wrote:You are calculating it by multiplying the intake consumption with the volumetric fraction (why are you dividing it by two?!), that seems okay.
This indeed yields 4,3 (or 8,7 when not divided by two).

This is the volume of gaseous fuel that passes the engine in one minute.
I don't get why you are dividing by two so I'll work with 8,7 from now on.

Divide the volume by the molar gas constant:
8,781295781/24,12941111=0,363924993 mol
This is the number of mol of fuel that passes in one minute.

Multiply this by the molar mass:
0,363924993*114,2656=41,58410773 g
This is the mass of the amount of fuel that passes in one minute.

Density of liquid: 688 kg/m^3
Divide by 1000 and then by the density.
(41,58410773/1000)/688=6,0442E-05 m^3
This is the volume of the liquid fuel that passes in one minute.

Multiply by 10^6 to convert m^3 into cm^3:
60,44201705 cm^3 (or mL, or cc) per minute!

So it consumes about 1 cc of liquid fuel per second.
Feel free correct me if I'm wrong, but I think this is it.


You sound right. Thank you. Oh and by the way it is divided by two because it is a 4 stroke engine. This means in only takes fuel in every other down stroke
  • 0

Image
User avatar
rcman50166
Colonel
Colonel
 
Posts: 697
Joined: Sat Jan 19, 2008 7:11 pm
Location: Bethel, CT
Reputation: 0

Return to Non-Spudgun Related Discussion

Who is online

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

Reputation System ©'