Fuel heating value calculation 2

[21121956]

Hello everybody:

The book "Gas Turbines Combustion" by Arthur Lefebvre, shows that the Lower Heating Value for a fuel oil can be calculated as follows:

LHV = 51,5 - (5,95/(1,53-dr)) [MJ/kg]

where dr = relative density of the fuel oil.
In other forum (unfortunately I am not able to find out) the engineer 25362 has set the following equation:

Pinf = 9380 + 26(ºAPI) [kcal/kg]

I have made some calculations for Bunker C (fuel oil grade Nº6) with an API of 12,1 to which corresponds a Relative Density of 0,9848 and the results are quite different.

Any comment on this subject will be very much appreciated.

 

[25362]

Using both formulas I got about the same answer:

51.5 [5.95[÷](1.53-0.9855)]=40.573 MJ/kg = 9691 kcal/kg

12.1[×]26 + 9380 = 9695 kcal/kg

Considering the accuracy of those two formulas, I'd say both results are equivalent. Wouldn't you ?

 

[21121956]

Hi 25362:

I accept that I have made a mistake calculating with the first formula; and you are right, both formulas give the same result. Thank you.

 

[quark]

LHV = NCV? Thanks to both of you, anyhow. I checked for few fuels and am getting NCV values using these equations, but confirm me.

Regards,

 

[25362]

Both above formulas refer to the NCV.
NCV = LCV; in Spanish, we used to call it Poder Calor[í]fico Inferior.

Quark, yours is a fitting question. Some equipment manufacturers indeed prefer to use the term heating value to indicate the amount of useful heat that can be extracted from a fuel, that is the CV multiplied by the efficiency.

Some years ago, UK practice preferred GCV (G for gross), while continental and US practice has been to use NCV, which for the same appliance results in a higher efficiency figure.