Corrected fuel consumption 1

[Bribyk]

I am familiar with the methods of correcting power for ambient test conditions but how is this done for fuel consumption, particularly gaseous fuels? Is this addressed in the various correction methods (ISO, SAE, DIN, JIS, etc...)?

Corrected (brake-specific) fuel consumption isn't as simple as dividing your corrected power (bhp) by the fuel flow rate (g/bhp-hr or Btu/bhp-hr), is it? I'd think this would yield inflated economy figures... How do you find corrected fuel rate?

 

[ivymike]

if you know your fuel flow in g/hr, why would you expect to have a wrong answer when you use that with corrected power?

 

[black2003cobra]

I would suggest making your performance map by taking the measured fuel consumption and dividing that by the measured uncorrected power. As power goes up and down with air density, so will the fuel consumption for a given AFR. So I'd just calculate that ratio, and call it a day.

 

[patprimmer]

On a stationary engine t is that simple.

In a car being driven on a road, air density will also effect aero and then it gets real complicated.

Regards

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[Bribyk]

This is a stationary engine application. The engine manufacturer measures both corrected fuel (natural gas) rate and corrected fuel consumption in their testing. I have their corrected fuel consumption numbers and need to be able to compare our measured values with theirs but, obviously, the air temperature and pressure will be different. So, I'm wondering how they are correcting their consumption. If I divide corrected power (will be higher than measured) by measured fuel consumption (lower due to lower air density) I would expect optimistic consumption/efficiency values.

Black2003cobra confirmed my intuitions. I'd think this linear relationship would hold within the acceptable operating limits of the engine.

Maybe the manufacturer has some proprietary formula worked out or they're talking about correcting for the fuel gas composition and not ambient air conditions.

 

[catserveng]

Most large industrial engine manufacturers reference ISO 3046-1 for power and fuel correction methods. Your engine manufacturer will need to supply some of the information for the calculations.

When doing power plant commissioning and some larger gas compression systems this was the reference and procedures we used. Also look at ISO 3046-3 for reference on test measurements.

Hope that helps