Fuel Consumption Rate

Approximate Diesel Generator Fuel Consumption Chart

Only the manufacturer would know definitely. (Your numbers are wildly inconsistent.)

0.1 US gallons/kWh which converts to 0.3785 L/kWh as IdeaSmith says sounds about right. With density 0.85 kg/litre and CV 44 MJ/kg it comes to an overall efficiency ~ 25%.

Depending how the generator is used and loaded for a camp application, the 25% overall efficiency might be a little high. But this does seem to be the best answer so far. GA

Thanks Ried

If we ignore the conversion error, the OP is saying that he has been told both .37 l/kWh and .3/kWh. Given that even small diesels can be over 40% efficient and the generator can be over 90%, (for 36% overall) then the lower consumption number is plausible. Therefore, picking one number over the other seems premature, given that we don't know how accurate the OP wants to be.

Your efficencies are at peak operating points. Since this gen set will run at a wide variety of loaded conditions, 20-25% is probably a reasonable number for new condition.

I agree that efficiency could be as low as 20-25%. However, the OP appears to want a relatively precise figure, given that he already has two figures that differ by a little more than 20%. I'm guessing he is asking for a source because he wants to be able to pin down a number based on his loading conditions.

We can only guess about his loading pattern. From his other post, however, we at least know the rough size of the generator, and we could guess that it runs at half load.

From this chart, we can see that a 400 kW generator running at half load uses only .28 l/kWh, substantially better than 20-25% efficiency. (This is a bit lower consumption than the lower figure OP was given.)

Surprising a generator this size is not being delivered with a manual, or sold by someone without access to actual consumption figures.

These figures are usually present in advertising and user manuals for a given generator. If you don't have thse then try googling the manufacturers data.

If you don't want to do that - at least tell us the brand and capacity (model number) of the device.

I just looked up the fuel consumption for a Caterpillar diesel engine in one of my crawler tractors. It was published in several places, including the Chinese clones of the Cat engine...it was in units of grams of diesel per kW-hr of engine output. As a cross-check for your data, the numbers were 200gm/kW-hr for a 950 cubic inch 6 cylinder turbocharged engine.

If you can get the specific fuel consumption from the manufacturer of the engine you are using, then you should be able to calculate the fuel usage, given your loads and some allowances for inefficiencies.

If you are talking about a manufactured genset, you should be able to get the data directly from the manufacturer of the genset.

Google is your friend here.

Jon.

I think you don't have the latest "app" to convert US gals to EU litres do you?

not to worry help is at hand...

1 US gal = 3.785L

I think you got your decimal point in the wrong place.. easy done when using fingers!

Cant you try to move away from the books? Try to do the following proceedure:

1. Fit new filters to your prime mover, change lube oil and air cleaner. Ensure there is no play at the coupling between prime mover and the alternator.

2. Feed you fuel supply line and return line into an empty container which will be your temporally tank. Put in 50 to 100 litres of diesel depending on the size of your engine. Bleed the fuel system and start engine.

3. Try to keep the engine running for an hour with all your electrical appliances on (at full load).

4.Measure the fuel remaining in the container to know how much fuel has been used in an hour. You should be able to calculate how much fuel you will be requiring in a day at full load. Am sure all you are looking for is to know the cosumption and use this in your badgeting, isnt it?

I have suggested this because you have not indicated the age/condition of your prime mover, the type and even model. On top of this, a number of factors may affect the fuel consuption of an engine -thus diverting from what the manufacture says. So, the proceedure above will be unique to your engine and not all the engines of the same type and make like yours.

just in case you need further help...

Contact the generator manufacturer. Most, if not all, generator manufacturers have test done on each model they produce that will give the gallons per hour used at full load and at half load.

Why are you asking the same question for a second time in 5 days?

We seem to be flodded with people who ask questions and can't comprehend the simple straight-forward answers provided by this forum.

I think the old post was was understood to be an existing installation, and he was basicly told to measure rather than calculate the results.

This post seems to indicate a proposed design, and the poster wants to extimate how much fuel might be used so to estimate the cost of fuel used.

The 0.1 gal/kwh seems to be a reasonable estimate for fuel consumption. The estimated camp energy consumption would possibly be 50% of the connected load.

Multiply the weekly kwh consumption by 0.1 gal per kwh, and you will have the approximate fuel used. Or at least a number you could use to estimate how often to full the tank each week.

Your conversion is not correct.

But aside from that, there is no substitute (assuming you want an accurate number) for looking at the manufacturer's data. We can throw out guess and estimates all day long, but the numbers vary dramatically from small cheap generators to large expensive ones, (etc. etc.). The alternative, also stunningly obvious, is to test the fuel consumption. Load with a representative load, and see how much fuel is used.

Understand, of course, that the figure in (kg/kWh or other units) changes with load. The closer the generator is running to its design loading, the better the match with the "book" figure. If the generator is large, and the manufacturer thoughtful, then you should be able to get the fuel consumption map (or at least a curve) which will show the BSFC (brake specific fuel consumption) for different loading conditions.

Also need to consider altitude

I believe the most appropriate approach in determining the actual consumption of your generator is first to check the basic technical data it has such as genset model, serial number (or arrangement number), name of manufacturer, etc. These are normally found from the serial number label of the affected generator. Next is to verify such data that you need from the local generator dealer within your area. I believe they will not be hesitant to do so since this is part of their product support responsibilities.

Certain considerations you have to put in place before determining your generator fuel consumption. First is to evaluate the actual loading of your generator set for a specified period of time. Since loads vary depending on condition, I believe it will be more appropriate to get the average. Specific fuel consumption released by the manufacturer are obtained when engine are at ' full load ' or ' at rated '.

If your generator does not operate at such, that is the time you have to consider the average load within specified time (i.e. 8 hours, 12 hours, one week, etc.). Normally fuel consumption are measured at lbs/kw-hr. This you will need a calculator to either convert them into liter or gallons. Lastly, your engine and alternator assembly should be operating in A1 condition in order to determine its actual fuel consumption against specification. Some indicators of generator not running within standard condition are excessive black smoke from the exhaust especially at full load operation, engine overheating indication from the water temperature gauge, voltage fluctuation, engine hunting, etc.

You can check your local generator dealer for help on this area to correct such problem occurrences. Looking forward in hearing from you.

Engr. Henry L. Maghinang

Best most accurate method would be to install a meter.

See my detailed post in the other thread.

Dipstick.