Monitoring Diesel Engine Fuel Consumption with Fuel Flow Meters

As carbon footprints and green-thinking come to mind, so does the inclination to steer away from gas engines and turn towards diesel fuel. Because of this, diesel engines are increasingly becoming utilized as a whole for a variety of power applications, such as:

  • Generators
  • Boats
  • Trains
  • Hydraulic packs
  • And more!

However, fuel consumption and efficiency are generally not monitored for diesel engines, which in turn, compromises the unit’s performance data. This must be gauged from the manufacturer’s test figures, and then is likely never checked again.

Following the increase of fuel cost and spending, the possibility of theft from remote installations or any other factors is certainly high. Consequently, monitoring fuel consumption of diesel engines becomes progressively important for transport industries in particular.

Vehicle manufacturers also take much time and effort checking their fuel consumption figures on dedicated dynamometers and sophisticated mobile setups for their diesel engines. These fuel systems are not only extremely costly, but also are unsuitable for general use.

On quintessential diesel engines, the fuel is supplied to the injectors at pressure from a “lift pump”. The injectors use the amount of fuel that is required for the engine load and return the remaining to the fuel tank. If the intention is to measure the amount of fuel used, it is very simple to place a single fuel flow meter in the supply line and one in the return line, using the electronics to subtract the difference.

Making this measurement, however, is not an easy task. The table below shows a hydraulic power pack running at a relatively constant speed, making the metering somewhat easier, as the ratio of maximum to minimum fuel consumption is small. Meanwhile, a commercial road vehicle would typically have a larger ratio compounding the metering issues.

Engine power Fuel consumption “Lift pump” Flow Return fuel Flow
kWm lph lph lph
970 224 570 346
880 202 567 365
660 151 560 409
440 102 555 453
220 54 550 496

Diesel Engine Fuel Consumption

Courtesy of Titan Enterprises

An example: if two low accuracy fuel flow meters in the flow and return lines of a diesel engine each have an accuracy of ±2% of reading and the instrument performing the subtraction is absolute, the figures are shown in the chart with the possible reading bands within the accuracy of the fuel flow meters.

To learn more about monitoring diesel engine fuel consumption, please contact JLC International today! Our experts are also able to explore any details pertaining to air velocity transmitters, shaw dew point meters, or even industrial humidity sensors.