[aditya.purkar]

I have simulated 1 cylinder diesel engine and now I want to check combustion efficiency.. How to calculate this?

[Yaju]

Combustion efficiency can be calculated by monitoring the integrated/chemical heat release in the cylinder at EVO.
It will be the integrated_heat_release_EVO/(total_fuel_injected*LHV_fuel). To get the integrated heat release, look at column 11 of the thermo_region#.out file for the cylinder region.
Getting the LHV of fuel will take some work. You will need to run another case for a few iterations with some modifications in your setup. If you are using v2.4, make the lhv_flag = 1 in inputs.in file, and include another file called "lhv.in" in your run folder with the following content:

44000000.0              lhv 
1                       lhv_num_species         
<FUEL_NAME>             1.0

Run the case with the above modifications for few iterations/time-steps. CONVERGE is going to write a file called lhv_info.out. Look at the line with "LHV CALCULATED BY CVG", the value here is the LHV of fuel based on the therm.dat file you provided. Use this value for your combusiton efficiency calculation.

[aditya.purkar]

thank you for your reply, but IHRR @ EVO is not giving proper heat released in my case may be because I have started simulation with EVO and injection is approx. after 600CAD. I've attached IHRR graph with this, please guide further

[Yaju]

I should have said EVO after combustion. Assuming 130 CAD as your start time and EVO, the next EVO will be at 130+720 = 850 CAD. At 850 CAD, your IHRR is about 17000 J, divide this by LHV_fuel*total_fuel_injected to get the combustion efficiency.

[aditya.purkar]

Got it. Thanks for the help