Can someone tell me the definition of A:F ratio?

Is it A:F ratio by volume?

by mass?

or, by reaction stoichiometry?

In other words, when we say 13:1 ratio, how is the sensor measuring the ratio (by volume, mass or stoichiometric coefficient)? TIA.

-Sean

 

It sounds like it goes by volume.

To me, at least.

 

What is the context. In other words...what specific question are you trying to answer?

 

I THINK he means, when one says such and such has an AF of 13 parts air to 1 part fuel, what unit of measurement is the "part?" A cubic mm? cm? in? mg? etc.

 

http://www.globaldenso.com/TEC....html

maybe of some help

 

It can be by whatever unit of measure that you want since it's a ratio.

Each part is commonly measured either by volume (cc's/mL's), weight (pounds) or mass (grams), or moles. You can convert b/w any of them using conversion factors.

The theoretical AFr they speak of in the article is commonly referred to as lambda. Lambda is the theoretical AFR at which all of the air and fuel is consumed under ideal conditions. We use lambda instead of a single specific AFR b/c different fuels require different AFR's to achieve lambda. eg: Methanol requires 8:1, gasoline requires 14.7:1, propane 18:1. The numbers aren't exactly correct, but you get the idea.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by IN VTEC &raquo;</TD></TR><TR><TD CLASS="quote">It can be by whatever unit of measure that you want since it's a ratio.</TD></TR></TABLE>

But because airs mass and volume changes with things like pressure and temperature, and fuel probably not at the same rate, I would think, different messures could give different results.

 

If you really want to be particular about it, then you can use correction factors to adjust for temperature and pressure with the density when converting from volume to mass or moles.

 

it is a ratio...so i think it can be whatever you want to measure it in as long as the relationship is the same.

 

It's mass ratio. In kg. That's the only accurate ratio. You cannot use volume because it changes with temperature and pressure.

 

moles or mass...either one

 

moley moley moley moley moley moley.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by El Pollo Diablo &raquo;</TD></TR><TR><TD CLASS="quote">moles or mass...either one</TD></TR></TABLE>
If your eyes are good, you can count the molecules. I'd rather use mass.

 

have fun weighing air...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by El Pollo Diablo &raquo;</TD></TR><TR><TD CLASS="quote">have fun weighing air...

</TD></TR></TABLE>

Hehehehe. Some cars use Air Mass meters, like the Scoob. A hot wire at the intake.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DutchITR1689 &raquo;</TD></TR><TR><TD CLASS="quote">
Hehehehe. Some cars use Air Mass meters, like the Scoob. A hot wire at the intake.</TD></TR></TABLE>

which measures air velocity through the intake....which then corresponds to volume....and in conjunction with the temp sensor mas can be estimated

thanks for playing

although we're getting a bit off-topic though

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by El Pollo Diablo &raquo;</TD></TR><TR><TD CLASS="quote">

which measures air velocity through the intake....which then corresponds to volume....and in conjunction with the temp sensor mas can be estimated
</TD></TR></TABLE>

Hehehe. http://www.sablesys.com/dynpress.html

"A mass flow meter, therefore, effectively performs a continuous STP correction. It's called a mass flow meter because it measures the mass, or molar quantity, of gas flowing through it per unit time - not the volume, which is a function of ambient temperature and pressure, and therefore useless for accurate work."


Modified by DutchITR1689 at 5:29 PM 10/5/2004

 

you may want to read that link thoroughly...