Heat Rate for large Diesel engines

[21121956]

Hello everybody:

I would like to get information regarding to the Heat Rate for large stationary medium speed Diesel engines.

I wonder if technical papers exist showing the experiences that establish a band or something like that, for the increase in Heat Rate accordingly with the time of operation of the engines?

Any help will be highly appreciated.

 

[abeltio]

heat rate is a concept mostly used for turbines (steam and gas)

for diesel (and gasoline) motors the concept most widely used is:
efficiency and specific fuel consumption.
the relationship in International Units between heat rate and efficiency is:

Heat Rate = 3600/[η]

[Heat Rate]= KJ/KWh

the relationship between specific fuel consumption and Heat Rate is:

Heat Rate = sfc x LHV
KJ/KWh = [kg/KWh]x[KJ/kg]

for combined cycle plants using diesel engines the Heat Rate is also used.

if you google "diesel engine" "heat rate" you get 800+ results, e.g.

http://www.manbw.dk/documents/p291_0108.pdf

saludos.
a.

 

[21121956]

Hi abeltio:

The data supplied by you already form part of my knowledge about this subject, but anyway, thanks.

The intention of my post is to ascertain where the increase of sfc comes from.

Our engines during almost 12000 hours of operation (without overhaul) have experienced an increase in the Heat Rate from 7780 BTU/kWh to 8070 BTU/kWh with LHV.

We have in correct operating conditions the inlet air filters, the charge air coolers, properly calibrated the fuel injection pumps and injectors, clean nozzles rings of turbochargers, etc.

The only weak point we guess exists is that, for cleaning the turbines and compressors runners of the turbos, we have to reduce the nominal engine load from 16,5 MW to 2 MW during a period of 20 to 25 minutes.

 

[taylorg]

After 12,000hrs the wear on your piston rings and exhaust valves will be a major factor, plus all the factors you mention above. Any excess wear etc on bearings, cams, liners etc would also contribute.
Also, remember that your turbocharger compressor and turbine blades are never completely cleaned by water washing and will very gradually become fouled.
Your figures above show a 3.5% increase, which doesn't give a huge cause for concern but does suggest you should be getting ready for an overhaul!
As I think I mentioned in another thread, your fuel quality and operating regime have a huge impact on the condition of your engines.
By the way, are you are running 18V46 units? Your output looks pretty close to that.

 

[21121956]

Hi taylorg:

Thanks a lot for your comments. Yes, our engines are 18W46.