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enord
31st January 2010 - 12:24 PM
1 gallon of natural gas yields 2 gallons water after combustion?
Bivalves
31st January 2010 - 12:41 PM
QUOTE (enord+Jan 31 2010, 12:24 PM)
1 gallon of natural gas yields 2 gallons water after combustion?

More wrong than Joseph Fritzl - you incredible idiot!
adoucette
31st January 2010 - 02:42 PM
QUOTE (enord+Jan 31 2010, 07:24 AM)
1 gallon of natural gas yields 2 gallons water after combustion?

You asked about a gallon of natural gas.
Natural gas is the typical name for Methane (CH4) and is a gas that we measure in cubic feet.
Gasoline is a liquid that we typically measure in gallons.

I'm assuming your question refers to Gasoline and not Natural Gas.

If so, you can work it out based on atomic weights and get a reasonably accurate value for the amount of water produced.

First though, gasoline is not one chemical, and its makeup varies by manufacturer, oil used to make it, season etc.

However we can reasonably simplify this calculation since gasoline is predominately Octane which has carbon and hydrogen in the ratio of C8H18, (the ratio of the other hydrocarbons in gasoline are also generally CnH2n+2).

So assuming our gasoline is all Octane, then when it burns you get this:

2 C8H18 + 25 O2 = 16 CO2 + 18 H2O

Atomic Weights of the constituents:
H = 1
C = 12
O = 16

Thus Octane is 84% Carbon and 16% Hydrogen

Octane weighs 6.3 lbs per gallon

So when you burn a gallon of gasoline, 16% of that 6.3 lbs is Hydrogen or ~1 lb.

Since the weight of Water is 9 times the weight of the Hydrogen it contains, there is 1 lb of Hydrogen in 9 lbs of water.

Since water weighs 8.3 lbs per gallon, this means for every gallon of gasoline you burn you get a bit more than a gallon of water, or ~1.07 gallons.

Arthur




enord
31st January 2010 - 03:17 PM
thanx. i was analogyzing ng to propane. using i therm [100,000 btu] of NG as a gallon equivalent.
cH4 +2o2= co2 + 2H2o? molar weight of ch4 & h2o are similar enough i think.
adoucette
31st January 2010 - 08:12 PM
QUOTE (enord+Jan 31 2010, 10:17 AM)
thanx. i was analogyzing ng to propane. using i therm [100,000 btu] of NG as a gallon equivalent.
cH4 +2o2= co2 + 2H2o? molar weight of ch4 & h2o are similar enough i think.

Yes, they are close.

CH4 = 16
H2O = 18

With a molecule of water weighing a bit more than one of Methane.

So since CH4 + 2 O2 = CO2 + 2 H2O

means you get two molecules of water per molecule of Methane, then 1 lb of CH4 when burned will yield 2.25 lbs of water.

Arthur
enord
31st January 2010 - 09:00 PM
QUOTE (adoucette+Jan 31 2010, 03:12 PM)
Yes, they are close.

CH4 = 16
H2O = 18

With a molecule of water weighing a bit more than one of Methane.

So since CH4 + 2 O2 = CO2 + 2 H2O

means you get two molecules of water per molecule of Methane, then 1 lb of CH4 when burned will yield 2.25 lbs of water.

Arthur

thus i can assssssume 1 gal [100k btu] NG will yield 2 gal h20?
how about propane? 1 gal lp yields ? gal. h2o?
adoucette
1st February 2010 - 05:31 AM
QUOTE (enord+Jan 31 2010, 04:00 PM)
thus i can assssssume 1 gal [100k btu] NG will yield 2 gal h20?
how about propane? 1 gal lp yields ? gal. h2o?

Again, we don't measure a gas in gallons, so the statement 1 gal NG has no specific meaning.
It would depend on the pressure the gas was at.

Again 1 POUND of NG will yield 2.25 POUNDS of Water.

Propane is C3H8

So C3H8 + 5 O2 = 3 CO2 + 4 H2O

Which means you get 4 water for 1 propane, and a molecule of propane weighs in at 44 and water is 18, so 18 X 4 = 72, so you get 1.6 pounds of water per pound of propane.

But propane has a lower specific gravity than water, and weighs only 4.11 lbs per gallon.

Thus even at a 1.6 to 1 ratio, burning 1 gallon of propane will only produce 6.7 lbs of water, which is 4/5ths of a gallon.

Arthur


enord
1st February 2010 - 01:23 PM
QUOTE (adoucette+Feb 1 2010, 12:31 AM)
Again, we don't measure a gas in gallons, so the statement 1 gal NG has no specific meaning.
It would depend on the pressure the gas was at.

Again 1 POUND of NG will yield 2.25 POUNDS of Water.

Propane is C3H8

So C3H8 + 5 O2 = 3 CO2 + 4 H2O

Which means you get 4 water for 1 propane, and a molecule of propane weighs in at 44 and water is 18, so 18 X 4 = 72, so you get 1.6 pounds of water per pound of propane.

But propane has a lower specific gravity than water, and weighs only 4.11 lbs per gallon.

Thus even at a 1.6 to 1 ratio, burning 1 gallon of propane will only produce 6.7 lbs of water, which is 4/5ths of a gallon.

Arthur

thanx. looks like my original assumption was only off by 100%! so
1 gal. propane= .8 gal. h2o
1 therm natural gas= .9 gal h2o

1 therm=100 cubic feet, 100,000btu approximately..........i forget what pressure the gas co. pipes it in at & wonder how much that 100 cubic feet of ch4 would weigh.
adoucette
1st February 2010 - 02:11 PM
QUOTE (enord+Feb 1 2010, 08:23 AM)
thanx. looks like my original assumption was only off by 100%! so
1 gal. propane= .8 gal. h2o
1 therm natural gas= .9 gal h2o

1 therm=100 cubic feet, 100,000btu approximately..........i forget what pressure the gas co. pipes it in at & wonder how much that 100 cubic feet of ch4 would weigh.

The DOE gives 22,453 BTU/lb as the heat value of fuel in a high efficiency burner.
Since these run around 95%, so that works out to 23,674 BTUs per pound, or 4.23 lbs of CH4 per Therm.

4.23 X 2.25 ratio = 9.52 lbs of water

9.52 = ~1.14 gallons of water per Therm.

Arthur
enord
1st February 2010 - 02:42 PM
QUOTE (adoucette+Feb 1 2010, 09:11 AM)
The DOE gives 22,453 BTU/lb as the heat value of fuel in a high efficiency burner.
Since these run around 95%, so that works out to 23,674 BTUs per pound, or 4.23 lbs of CH4 per Therm.

4.23 X 2.25 ratio = 9.52 lbs of water

9.52 = ~1.14 gallons of water per Therm.

Arthur



so 1gal. propane = .8 gal. h2o
1 therm ch4= 1.1 gal h2o

the resultant humidity from unvented combustion is my concern. THANX AGAIN
adoucette
1st February 2010 - 03:17 PM
You're welcome.

Arthur
enord
1st February 2010 - 08:06 PM
gotta add that i used the term "gal. of ch4" initially because "fuel cost calculators" use therm for ng & gal. for propane, so i figured there was a similarity which as u figured out = the weight of a therm is similar to the weight of a gal. of propane
light in the tunnel
2nd February 2010 - 02:14 PM
1 cubic foot = @7.5 US gallons

1 US gallon = @0.13 cubic feet

Just thought I'd post this since there were repeated statements about unconventionality of measuring LP and NG in gallons (and presumably measuring water in cubic feet).

Here's a radical idea: What about using liters and CCs standard for convenience?
enord
2nd February 2010 - 03:02 PM
QUOTE (light in the tunnel+Feb 2 2010, 09:14 AM)
1 cubic foot = @7.5 US gallons

1 US gallon = @0.13 cubic feet

Just thought I'd post this since there were repeated statements about unconventionality of measuring LP and NG in gallons (and presumably measuring water in cubic feet).

Here's a radical idea: What about using liters and CCs standard for convenience?

not convenient for explaining to the layman in the u.s. A did well rationalizing this i think. unvented gas heaters are a source of concern & illegal in some states
light in the tunnel
2nd February 2010 - 04:48 PM
QUOTE (enord+Feb 2 2010, 03:02 PM)
not convenient for explaining to the layman in the u.s. A did well rationalizing this i think. unvented gas heaters are a source of concern & illegal in some states

"Gallons of water per unit room volume" is also inconvenient for laymen.

If you want to convert the units to truly accessible layman terms, I would factor the volume of the living area and the temperature with the amount of water generated per-hour and talk in terms of relative humidity and the amount of condensation that will form.
enord
3rd February 2010 - 11:48 AM
QUOTE (light in the tunnel+Feb 2 2010, 11:48 AM)
"Gallons of water per unit room volume" is also inconvenient for laymen.

If you want to convert the units to truly accessible layman terms, I would factor the volume of the living area and the temperature with the amount of water generated per-hour and talk in terms of relative humidity and the amount of condensation that will form.

2complicated. RH is lolow near heatsource & high at colder areas [i think] & the affect of the wind drafting thru the house makes a diff. digital humidity meters are cheap & accurate. window condensation tells some of the story.
light in the tunnel
3rd February 2010 - 04:15 PM
QUOTE (enord+Feb 3 2010, 11:48 AM)
2complicated. RH is lolow near heatsource & high at colder areas [i think] & the affect of the wind drafting thru the house makes a diff. digital humidity meters are cheap & accurate. window condensation tells some of the story.

First you claim liters is inconvenient for "laymen." Then you say relative humidity is too complicated to calculate. Who do you want to cater to, laymen or people who understand science and unit conversions?
enord
3rd February 2010 - 09:09 PM
QUOTE (light in the tunnel+Feb 3 2010, 11:15 AM)
First you claim liters is inconvenient for "laymen." Then you say relative humidity is too complicated to calculate. Who do you want to cater to, laymen or people who understand science and unit conversions?

actually a laywoman who cares only to push a cheap,safe button to gain the creature comforts......imagine that!
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19th March 2010 - 07:11 AM
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Bloy
20th March 2010 - 06:25 PM
QUOTE (vvwin13+Mar 19 2010, 01:11 AM)
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buttershug
23rd March 2010 - 04:02 PM
QUOTE (Bloy+Mar 20 2010, 06:25 PM)
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