bcavender
Electrical
- May 31, 2018
- 104
A friend asked me to calculate the exhaust products that would be produced by a propane powered IC engine generating 5kw electrical at a fuel efficiency of 33%.
This is my first cut at the solution … but engines are not my expertise at all and my chemistry skills are inexperienced at best.
I am seeking someone at a higher pay grade than myself to review this calc for any corrections or sanity mods needed.
All comments welcome!
Best regards,
B
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C3H8 MASS FLOW CALC
5 Kilowatts (Electrical) Delivered for 1 hour
33% Fuel Efficiency => 15kWh fuel input
1kg of propane = 14.019 kWh
1.07 kg propane mass required/hr
1kg propane = 22.678 moles
Propane fuel mass input = 24.265 moles
Chemistry:
C3H8(g) + 5O2(g) -> 3CO2(g) + 4H2O(g)
24.265 moles propane + 121.33 moles O2
produces:
72.795 moles CO2 + 97.06 moles H2O
Mass of nitrogen ingested for Stoich:
21% O2 in the atmospheric => 4.762 N2 ratio
N2 ingested = 122.33 molesO2 x 4.762N2 ratio
= 577.75 moles N2
Hourly Exhaust Mass @ 5 kWh(e):
72.795 moles CO2. (@44.01 g/mol)
97.06 moles H2O. (@18.015 g/mol)
577.75 moles N2. (@28.013 g/mol)
Makes:
3204 g CO2
1752 g H2O
16185 g N2
21.149 kg/hr total combust mass flow @
15.155% CO2, 8.287% H2O & 76.56% N2
VOLUMETRIC FLOW
STP Molar Gas Volume = 22.4 liters
747.60 total moles
747.60 mol x 22.4 liters = 16,746 liters/hr
.0353 ft3 / liter
591.1 cubic feet / hour @STP