Calibration of Diesel Generator Power and Fuel Consumption Rate

A.Calibration of diesel generator power.

The effective power and corresponding speed of the diesel generator are clearly specified on the nameplate of the diesel generator and in the instruction manual.The effective power and the speed marked on the nameplate are called the calibrated power (rated power) and the calibrated speed (rated speed), which are collectively referred to as the calibrated working condition. The calibration of diesel generator power is comprehensively determined according to the characteristics, service characteristics, life and reliability requirements of diesel generators.

At present, according to the national standard GB1105.1-1987 Standard environmental operating conditions and calibration of power, fuel consumption and oil consumption of internal combustion engine bench performance test methods, the rated power of diesel generators is divided into four types.

1.15min power: in the condition of a standard environment (atmospheric pressure 100kPa, relative humidity 0-30%, ambient temperature φo=298K or 25℃, the inlet temperature of the cooling medium of the intercooler Tc0=298K or 25℃. ) , diesel generators are allowed to run continuously for 15 minutes of rated power.

2.One hour power: under standard environmental conditions, the diesel engine is allowed to run continuously for one hour at the calibrated power.

3.12 hours power: under standard environmental conditions, the diesel engine is allowed to run continuously for 12 hours at the calibrated power.

4.Continuous power: The calibrated power allowed for long-term continuous operation of diesel generators under standard environmental conditions.

The 15min power is for automotive diesel generators, such as cars, motorcycles and motorboats. It runs at the highest speed when overtaking or chasing. It is allowed to run at full load within 15min. During normal driving, it runs at the calibrated power of the diesel generator. For vehicle diesel generators, usually 1h power is used as the rated power, 15min power is used as the maximum power, and the corresponding speeds are the rated speed and the maximum speed. Automobiles often run at lower than the rated power, therefore, under normal circumstances, the rated power of automotive diesel generators is marked higher to give full play to the working performance of diesel generators.

Diesel generators for generator sets, marine engines and diesel generator cars usually use continuous power as the nominal power, and 1h power as the maximum power. The durability and reliability of diesel generators are very high for generator sets and ship navigation, and the power cannot be calibrated too high. The calibration of the operating power is a complicated task. The higher the operating power of the diesel generator is calibrated, the shorter its service life.

At present, the calibration of the power used by the product is based on the user's requirements and product performance, and is calibrated by the manufacturer.

B.The influence of environmental conditions on the performance of diesel generators.

The calibrated power of diesel generators is for a specific environmental condition. Environmental conditions refer to the ambient atmospheric pressure, temperature and relative humidity where diesel generators operate, which have a great influence on the performance of diesel generators. When the ambient atmospheric pressure decreases, the temperature increases, and the relative humidity increases, the dry air sucked into the cylinder of the diesel generator will decrease, and the power of the diesel generator will decrease. Conversely, the power of diesel generators will increase.

Since environmental conditions have a great impact on the performance of diesel generators, standard environmental conditions must be specified during power calibration. If the diesel generator works under non-standard conditions, its effective power and fuel consumption rate should be corrected to standard environmental conditions.

C.Correction of diesel generator power and fuel consumption rate.

The correction of diesel generator power is stipulated in B 1105.1-1987 Standard environmental operating conditions and calibration of power, fuel consumption and oil consumption of internal combustion engine bench performance test methods. Two methods of diesel generator power correction are regulated and the equivalent oil volume Law. The following describes the adjustable oil volume method in detail.

The adjustable fuel quantity method: the power limit of diesel generators is only limited by the excess air coefficient α. Therefore, the correction of diesel engine power should be based on the principle of equal α. When the environmental conditions change, the fuel supply should be changed accordingly to keep α unchanged. Under this condition, it is considered that the combustion situation and the indicated power remain unchanged, and the indicated power is written in proportion to the amount of dry air entering the cylinder and the amount of fuel.

Then, considering the impact of environmental conditions on mechanical losses, the effective power and fuel consumption rate are corrected. In the formula, the subscript with 0 indicates the value under standard environmental conditions, and the one without 0 is the actual measured value under the on-site environmental conditions.

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