Fuel Consumption Per Load in Kw or Kva

Use "the data provided by the manufacturer", "to make comprehensive comparison table to see the saving".

What's the problem?

First, one cannot do a theoretical calculation of fuel consumed to electric power because there are too many energy transfers happening simultaneously (chemical to thermal, thermal to mechanical, mechanical to electrical). Additionally there will be the complication of the random, variable electric load changes that will happen through out the day. So using the manufacturers numbers will be your best bet.

Having said that... I would expect that at close to maximum load, one larger diesel generator will be more efficient than two half the size smaller diesel generators. However, a large generator operating at just under half of its capacity will be less efficient than one half the size generator operating at most of its capacity. On the other hand operating any system at close to full load will likely produce early failures.

Most manufacturers will provide charts of fuel consumption versus load- generally not linear. These only provide approximations, but are reasonably close to actual measured values in the installations where I have done this.

The issue is that the load is never going to be constant. Trying to use an "average" load to calculate this can be misleading, since the relationship between load and fuel consumption is not going to be linear (except over a small range of values). Power factor can also play a role, as can any load imbalance.

The quickest way to conduct the investigation of two 400 kW vs one 8 KW generators is to compare the manufacturer-provided curves for the candidate plants.

The most exacting way to determine the actual fuel consumption is to measure the fuel consumed over a period of time (not the fuel flowing to the generator- some of that goes back to the tank. You have to measure how much fuel has been sucked from the tank over the given period).

From the specifications you cited, I would say that "L/ph=107" is most likely Chinese or Korean for "Liters per hour", but you do not mention the make of generator you are using...Sounds about right from an energy standpoint.

Dear dar76,

The fuel consumption will NOT HAVE LINEAR RELATION WITH LOAD. The best performance is achieved at Loads more than 80% to 85% of RATED or FULL LOAD.

You have not indicated the load pattern. If the load will not come below 60% of Rated Load. then use single generator set. If the load drops below 50%, for example 30%, it is advisable to have 2 sets and at lower loads, isolate the 2nd set. This also depends upon how often the load comes down or goes up.

Manufacturers Consumption data is valid only the set is loaded to certain minimum level and when there is NO-LOAD, the DG Set will run in idle and fuel will be consumed perhaps 8 to 10% of fuel at Full Load, which is a waste.

THANKS,

DHAYANANDHAN.S

A dipstick and a clock is one method.

Intervals between quantities supplied is another.