[amin_u50]

Hello,

I was wondering how we can find the LHV of predefined fuel (e.x. DIESEL2) in CONVERGE. If I use SAGE model for natural gas/diesel dual-fuel engine, how can I find the LHV of natural gas (or methane) from the Mechanism?


Amin

[MFGT]

Thats the procedere for v2.3

Originally Posted by dprobst

The LHV of the fuel is calculated using property data in therm.dat. If you do not want to calculate it from the therm.dat data, you can get the calculated LHV of the fuel as an output from Converge. To get the LHV as an output, you will run a simple test case:
- create a hidden.in file with the following line:
1 lhv_flag
- create a file called lhv.in with the following lines:
2.0 lhv_value LHV VALUE TO BE ACHEIVED IN J/kg
1 lhv_num_species NUMBER OF FUEL SPECIES TO BE MODIFIED FOR LHV
c8h18 1.0 massfrac RELATIVE FRACTION OF EACH FUEL SPECIES


Run this test case for a short time - a file called lhv_info.out file will contain the calculated LHV as the second line (LHV SURROGATE). As this is a new feature, it is still in trial mode and has not been moved to a regular file input, and you will need a recent version of v2.3.

[amin_u50]

Originally Posted by MFGT

Thats the procedere for v2.3

Thank you for your answer. So, how we can calculate LHV from therm.dat?

[nitesh.attal]

Amin,

The Lower Heating Value is the difference between heat of formation of products (gas) and reactants. Note that the lower heating value also accounts for heat of vaporization, e.g for water.

Please see the section "Heat of Formation and Equilibrium Constants" in the following paper,
McBride, Bonnie J., Sanford Gordon, and Martin A. Reno. "Coefficients for calculating thermodynamic and transport properties of individual species." (1993).

Additional e.g.
HeatOfFormation(H2O gas)@1000K = Enthalpy(H2O gas)@1000K - Enthalpy(H2)@1000K - 1/2 Enthalpy(O2)@1000K
The polynomials coefficients in therm.dat can be used to calculate Enthalpy of H2, O2 and H2O.

Thanks,