Calorific value for hydrocarbons

Question

Calorific value for hydrocarbons

Emz80s (Chemical)

(OP)

15 Apr 22 15:22

Hi all
I ask why calorific value for ch4 is higher than all the other ( heavier hydrocarbons) like Ethane , propane ... despite all these heavier HC 'a should have more carbon atoms than ch4 !!

EdStainless (Materials) · Answer 1 · 2022-04-15 17:00:32

Chemistry.
Write out the reactions, calculate the Free Energy values.
It is a more optimal package.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

Emz80s (Chemical) · Answer 2 · 2022-04-15 17:58:25

I ask about the burning of Ch4
Why gives more heat than burning ethane for example ???
Reaction is the burning reaction
CH4 + 2 O2 → CO2 + 2 H2O (ΔH = −891 k J/mol,)

EdStainless (Materials) · Answer 3 · 2022-04-15 20:25:04

And your point is?
Look at the same for ethane, look at the ratio of CO2:H2O that you get.
And then covert moles to either a volume or a mass and compare.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

georgeverghese (Chemical) · Answer 4 · 2022-04-15 23:55:57

That is not what I see in Perry Chem Engg Handbook for std. net combustion heat values for methane and ethane:
C1 : 802kJ/gm mol
C2 : 1429kJ/gm mol

Values are based on product H20 in gas phase, while your value for C1 is for water in liquid phase

crshears (Electrical) · Answer 5 · 2022-04-16 00:05:01

Maybe the OP is running a condensing boiler and hasn't said so . . . another case of a paucity of information being provided . . .

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

pierreick (Chemical) · Answer 6 · 2022-04-16 05:59:03

Hi,
Take a look : https://www.engineeringtoolbox.com/heating-values-...

Pierre

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Calorific value for hydrocarbons