Home » Public Forums » GMCnet » Re: [GMCnet] yamaha inverter generator: how to run inside?
| Re: [GMCnet] yamaha inverter generator: how to run inside? [message #113183 is a reply to message #113181] |
Wed, 26 January 2011 13:36   |
Gary Worobec
Messages: 867
Registered: May 2005
Karma:
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Senior Member |
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Dr. Mike,
Excellent explanation. I really like the last paragraph. I think we should
all write our own Obit to avoid embarrassing ourselves when the time comes.
Thanks
Gary and Joanne Worobec
1973 GMC Glacier
Anza, CA
----- Original Message -----
From: "Michael Lincoln" <mlincoln1@gmail.com>
To: <gmclist@temp.gmcnet.org>
Sent: Wednesday, January 26, 2011 11:07 AM
Subject: Re: [GMCnet] yamaha inverter generator: how to run inside?
Lunch break time….
There was a question of oxygen starvation raised. As a pulmonary
physician, I couldn't let that go without trying to figure out if it was
likely to be true or not.
1. Combustion calculation:
1. Gasoline is a mixture of hydrocarbons, nominally about C8 H18
(isooctane), specific gravity 114.23 gm/mole
2. Stoichiometric complete combustion of hydrocarbons:
CxHy + (x + y/4)O2 --> xCO2 + (y/2)H2O
4. Substituting into the equation: C8H18 +(8 + 4.5) O2 à8CO2 +9H2O
5. Thus every molecule of isooctane completely combusted will yield 8
CO2 and 9 water molecules and consume 12.5 oxygen molecules
2. Determine how much isooctane is in a gallon of gas
1. Isooctane specific gravity 688 kg/m^3 liquid state
2. 1 m^3 = 1,000 liters = 264.172 gallons, so one gallon contains 2.60
kg of isooctane
3. 2,600 gms of gasoline / 114.23 gm/mole = 22.76 moles of isooctane.
3. Determine the waste products resulting from burning a gallon of gas
completely (assuming no CO, NO2, etc here…complete combustion into water and
CO2) All this goes out the exhaust pipe (Shan hopes!)
1. 22.76 moles burned x 9 = 204.84 moles water produced …at 18 gms/mole
that’s 18 * 204.84 = 3684.12 grams of water (almost a gallon)
2. 22.76 moles burned x 8 = 182.08 moles of CO2 produced…at 44.01
gm/mole that’s 8013.34 grams of CO2 produced. CO2 weighs (at standard temp
and pressure dry) 1.977 gm/liter, so that’s ca. 4000 liters of CO2 produced
(Global warming!)
4. Determine the oxygen consumed from burning a gallon of gas completely
1. 22.76 moles burned x 12.5 moles oxygen consumed/mole of gas burned =
284.5 moles of oxygen consumed.
2. With oxygen at 16 gm/mole, that’s 4552 gms of oxygen consumed when a
gallon of gas is burned. Oxygen’s density (100% oxygen) is 1.429 gm/liter
at zero centigrade (ok, you’re living in a cold coach). In room atmosphere
at sea level, with 21% oxygen, that’s ca. 0.30 gms oxygen/liter of room air.
3. If 4552 grams of oxygen are consumed, ca, 4552 / 0.30 = 15,173
liters of room atmosphere are going to be pumped through the engine. That’s
ca. 536 cubic feet of atmosphere. If the coach is 7.5 x 6 x 26 feet inside,
the total volume of the coach is ca. 1200 cubic feet.
Conclusion: A catalytic heater (which exhausts inside) doesn’t create
a negative pressure in the coach by dint of producing 8 CO2 and 9 H2O
molecules that take the place of every 12.5 molecules of oxygen consumed.
I'd say that a catalytic heater can surely deplete oxygen concentrations if
you burn enough fuel. If you could really use up 536 cubic feet of
atmosphere by running through a gallon of gas (or equivalent molar weight of
propane), using a catalytic heater, that'd be serious, and not just from
oxygen starvation but from CO2 acidosis. I suggest that nobody run a
catalytic heater without several windows open! On the other hand, an
internal combustion engine is a volume air pump and it exhausts all the air
it takes in. It thus creates a negative pressure that will be supplied by
leaks inward to the coach from the surrounding air. So I don’t think Shan’s
arrangement would necessarily cause oxygen starvation because as 21% oxygen
room air is consumed and pumped out more 21% oxygen atmosphere will leak
into the coach. I think one can practically guarantee that a 35 year old
coach _won't_ develop a subatmospheric pressure, even with the windows
closed: a multitude of small leaks will suffice to let in all the air
pumped out :-).
HOWEVER, I still have a dire concern that Shan will kill himself,
German engineering genes and all, from incompletely exhausted carbon
monoxide. Shan, think of how your obit might look: do you really want even
a small chance of that? Then there'd be the humiliating post-mortem
endowment, in your name, to the local firefighters. For the next 50 years
they'll to go to the elementary and high schools to warn kids about the
dangers of carbon monoxide poisoning, all in your name (imagine a
flower-wreathed picture on an easel in the gymnasium, standing to the
firefighter's podium, and the bored kids texting each other about what a
turkey you must have been to have engendered a perpetually endowed safety
assembly in your name). I know that such an ignoble end would be too
embarrassing for me by far.
Run the generator outside!
Now it is time to return to work!
Mike Lincoln
On Jan 26, 2011, at 12:59 PM, Shan Rose wrote:
>
>
> My Onan runs like a top, the reason for the smaller gen is 4 fold, one is
> the fact that it uses about .1 gal an hour at 1/4 load the onan with
> almost no load burns about .4 gallons an hour. Second is noise, unless
> running the roof AC, water heater, or some other electrical appliance
> which demands heavy current, the onan is overkill. Third is portability, I
> can take the smaller gen with me anywhere without having to drive the
> coach there. 4th is to reduce wear and tear on the onan, since mantainance
> costs are significantly more ofor the onan (last oil change for the onan
> was about $40, compared to just $6 for the yahmaha) the onan is a great
> genset, once I worked out the bugs, mine has provided me with several
> hundred hours or reliable service, and by splitting the load with another
> APU I can make the onan last even longer before a major overhaul will be
> required, so now I will only need onan under severe usage conditions and
> not just to nuke something or watch a little TV whe
> n im in my rig...
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