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#1
12-30-2007, 06:12 PM
 Unregistered Guest Posts: n/a
LPG kWh conversion confusion

I find reputable sites that say LPG is 11.xx kWh per litre, and others that say LPG is 12.xx per kg.

But one litre of LPG is about half a kg.

What is the correct conversion factor for LPG?
#2
12-31-2007, 05:33 AM
 JohnS Moderator Join Date: Dec 2007 Location: SE Michigan, USA Posts: 9,758 Rep Power: 20
Re: LPG kWh conversion confusion

I don't know if I can post a link yet. My source is
Hydrogen Analysis Research Center (apparently a section is US Dept. of Energy), Lower and Higher Heating Values of Fuels. See link at bottom of the page for source spreadsheet.
http://hydrogen.pnl.gov/cocoon/morf/...canprint=false

Note: Higher Heating value assumes water vapor in exhaust is condensed and heat recovered, Lower Heating value assumes it isn't. Automotive manufacturers use LHV, not sure about furnace guys.

For propane (LPG):
HHV = 50.152 MJ/kg
LHV = 46.607 MJ/kg
Density = 0.508 kg/L

Note: You used kWh. 1 kWh = 3.6 MJ (because there are 3600 s/h)
#3
12-31-2007, 07:17 PM
 Unregistered Guest Posts: n/a
Re: LPG kWh conversion confusion

Thanks John. Seems no doubt that those reputable sites giving LPG at 11 or 12 kWh per litre are simply wrong.
#4
12-31-2007, 09:07 PM
 Mrs X can't count, can't spell! Join Date: Feb 2006 Location: New Zealand Posts: 2,326 Rep Power: 12
Re: LPG kWh conversion confusion

Quote:
 Originally Posted by Unregistered Thanks John. Seems no doubt that those reputable sites giving LPG at 11 or 12 kWh per litre are simply wrong.
These might be quite close, as LPG can contain varying amounts of ethane and butane, which will have differing values, too.

12kWh x 3.6 = 43MJ, which is close to the 46.6MJ JohnS gave for the lower heating value. These values can change a bit, as the temperature of the liquid will play a part, too.
#5
01-01-2008, 03:44 AM
 JohnS Moderator Join Date: Dec 2007 Location: SE Michigan, USA Posts: 9,758 Rep Power: 20
Re: LPG kWh conversion confusion

Quote:
 Originally Posted by Mrs X These might be quite close, as LPG can contain varying amounts of ethane and butane, which will have differing values, too. 12kWh x 3.6 = 43MJ, which is close to the 46.6MJ JohnS gave for the lower heating value. These values can change a bit, as the temperature of the liquid will play a part, too.
On the kWh/kg figure, I absolutely agree. Any better figure requires chemical analysis of the gas and accounting for the ethane, butane, etc. Based on litre spelling, I suspect OP is not in the US, but US LPG is mostly propane (95%). Some countries apparently approach 50% propane, 50% butane.

For the liter figure to be 11/12 of the kg figure, density has to be around 0.9 kg/L. Even liquid butane is around 0.57 kg/L, propane, 0.51 kg/L. As you point out, this density will vary with temperature. Density of hydrocarbon fuels is almost always stated at 60 degrees F (15.6 C), but the API jealously guards the volumetric expansion coefficients so they can sell books of figures to temperature adjust density.
#6
02-11-2010, 02:39 AM
 lukasm Guest Posts: n/a
Re: LPG kWh conversion confusion

Quote:
 Originally Posted by Unregistered Thanks John. Seems no doubt that those reputable sites giving LPG at 11 or 12 kWh per litre are simply wrong.
can you please share where do you find such data?

thanks
#7
07-10-2011, 01:49 AM
 logu002 Guest Posts: n/a
Re: LPG kWh conversion confusion

i want to know 1 kg of lpg gas tends to howmuch kwhr

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