Propane flowrate, Day 5 & 6, a little late

For propane:

The formula for subsonic mass flow rate through an orifice is:

http://en.wikipedia.org/wiki/Orifice_plate#Calculation_of_expansion_factor

mdot is mass flowrate (kg/s)

C is the orifice flow coefficient (unitless), .61-.9 (we pick .7)

A₂ is cross-section area of orifice (m^2), ((.0265 in)^2) * pi = 1.42334131*10^-6 m^2

ρ₁ is upstream gas density (kg/m^3), ~11 kg/m^3

P₁ is upstream gas pressure (Pa or N/m^2), 80 psi = 551580 Pa

P₂ is downstream gas density (Pa or N/m^2), 60 psi = 413685 Pa

k is the ratio of specific heats (dimensionless), 1.127 (for propane at room temp)

http://www.google.com/search?q=.7*(.0265in)^2*pi*sqrt(2*11kg/m^3*80psi*(1.127/(1.127-1))*((60/80)^(2/1.127)-(60/80)^((2.127)/1.127))) = 0.00143057116  kg / s

So, the mass flowrate for propane will be about 1.4 grams per second, about the same as for the air flowrate (except we are operating the propane at a lower pressure). This means I'm going to have to have a much different orifice size for the propane versus the air, since the propane should only be about 4% of the total mixture by volume.

It's after midnight, and I didn't get to show pictures of the existing orifices for air and propane. I'll do that Monday sometime.