How Many Liters of Diesel Can a Generator Run for Forty Hours?
Understanding the fuel consumption rate of a generator, typically measured in liters per hour (L/h), is crucial for determining how much diesel you need to power your generator for a specific duration. In this guide, we will delve into how to calculate the total amount of diesel required and explore the factors that influence fuel usage, such as load and RPM.
Calculating Diesel Consumption for a Generator
To estimate the amount of diesel a generator can consume over a forty-hour period, you first need to know the fuel consumption rate in liters per hour (L/h). This information is typically found in the generator's specifications.
The formula to calculate the total diesel needed for a forty-hour runtime is as follows:
Total Diesel Needed (L) Fuel Consumption Rate (L/h) x Operating Hours (h)
Let's work through an example to illustrate this calculation.
Example Calculation:
Given a generator with a fuel consumption rate of 2 liters per hour (L/h) and a runtime of 40 hours:
Total Diesel Needed 2 L/h x 40 h 80 liters
If you have the specific fuel consumption rate for your generator, you can plug it into this formula to determine the exact amount of diesel required.
Factors Influencing Diesel Consumption
The amount of diesel consumed by a generator also depends on the load it is carrying. In general, the more load the generator is under, the more fuel it will consume. Conversely, operating under no load or at a lower load can increase the fuel consumption.
The formula to estimate fuel consumption can be simplified as:
Fuel Consumption Heating Value × (Fuel per Hour) × Efficiency
For diesel, the heating value is approximately 41 MJ/kg. Therefore, the calculation becomes:
Fuel Consumption (Liters/hour) 41 MJ/kg × (Fuel per Hour) × Efficiency
Engine RPM and Power Output
The performance of the generator, including fuel consumption, is influenced by the RPM of the engine. For instance, a Series 60 Detroit engine in a truck, rated at 500 horsepower (HP) at 2100 RPM, would be restricted to 1800 RPM for a 4-pole generator operating at 60 Hz. Assuming linear horsepower scaling with speed and 80% efficiency, the engine would be able to drive a 450 kW generator. At idle (600 RPM), the engine would burn around 3 liters per hour.
When cruising at 60 MPH, the engine would not be delivering maximum output, leading to higher fuel consumption. A rough estimate places this at around 10 "shrunken Yankee gallons" per hour, which is approximately 38 liters per hour. Without data on sustained maximum torque at 1800 RPM, we cannot provide an exact figure.
Comparison with Another Generator
For a larger generator, the consumption rate can be vastly different. For example, a locomotive’s SD40–2 engine, with a 3000 HP rating, and assuming it can drive a 2.7 MW generator, would burn around 18 liters per hour at idle, more at no load, and around 225 liters per hour at partial load.
A smaller generator rated at 9500 watts continuous has a 16 HP gas engine, with an 8-gallon fuel tank. It is rated for 6 hours of runtime at full load, which translates to a fuel consumption of 5 liters per hour at full load. Diesel engines are slightly more efficient in terms of fuel consumption.
Conclusion
While the general formula to calculate diesel consumption is straightforward, various factors, such as load and RPM, can significantly impact the actual fuel usage. Understanding these factors and the specific specifications of your generator is crucial for efficient operation and accurate budgeting.