International freight rate analysis

Detailed explanation of the calculation method of engine rated power The International freight rate analysisrated power of the engine refers to the maximum power that the engine can output under certain conditions. It is an important performance indicator of the engine, which is of great significance to the selection, application and maintenance of the engine. This article will introduce the calculation method of the engine rated power. I. Definition of engine rated power The engine rated power refers to the standard atmospheric pressure, the intake temperature is 15℃, the relative humidity is 60%, and the fuel is the standard reference fuel. Under the rated load of the engine, the gas inlet pressure is 0.1MPa, the cooling water inlet temperature is 84℃, and the cooling water outlet temperature It is 95℃, the fan braking power is 0, and the maximum power output of the engine.Generally speaking, it is the maximum power reached by the engine under specified working conditions. II. Engine rated power calculation method There are usually two calculation methods for engine rated power: measurement method and theoretical calculation method. 1. The measurement of the rated power of the measurement engine needs to be completed in a special experimental site. The method is to fix the engine on the test frame, measure the output power with a special power tester, and record the cooling water temperature, intake temperature, gas inlet pressure and other related parameters at the same time, and calculate them according to the power conversion formula. The measurement method can accurately obtain the rated power of the engine, but it requires more professional measurement equipment and site, and engineers also need to have rich experimental operation and technical experience. Two. Theoretical calculation method The theoretical calculation law is calculated based on the engine design theory and estimated the rated power of the engine in combination with the actual operating conditions.The calculation formula is: Pe = K1 × K2 × K3 × Ne, where Pe is the rated power of the engine, the unit is kilowatt (KW); K1 is the actual measured cylinder volume correction coefficient of the engine, K2 is the average effective pressure coefficient, K3 is the cooling efficiency coefficient of the heat dissipation system; Ne is The rated speed of the motive. Let's analyze the specific meaning of each coefficient one by one: K1 coefficient: Because in actual production, the actual measured cylinder volume will be different from the designed cylinder volume during engine manufacturing, so it needs to be corrected. The value range of the K1 coefficient is generally 1.05~1.15, and the value will also be different for different engine manufacturers and style series. K2 coefficient: The average effective pressure refers to the average value of the work done to the gas in the cylinder during the intake, compression, combustion, exhaust and other work processes in a cycle.The value range of the K2 coefficient is generally 0.75~0.85, and different types of fuel will also affect its value. K3 coefficient: the cooling efficiency coefficient of the heat dissipation system, that is, the proportion of the heat emitted by the engine, is usually 60~70%. With the continuous emergence of various high-efficiency cooling technologies, the K3 coefficient may be adjusted. Ne: The rated speed of the engine, that is, the speed of the maximum point of power. For the same type of engine, its rated speed is usually similar, so it can be selected according to the data given in the product parameter manual. Engines that meet user needs can also be realized through adjustment equipment such as transmissions. The above formula is only a general approximation, and the actual measurement comparison is the most accurate, but this calculation method can be used as an initial value in the selection, design and simulation stages. III.Conclusion The rated power of the engine is one of the important indicators of engine performance. Usually, the data obtained through theoretical calculation has a certain error with the actual measurement data, but it can still be used as an important reference for engine design and selection. For the selection of engines in different applications, comprehensive analysis and evaluation need to be carried out according to actual needs.

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