Methods for calculating fuel heating at injection with pressure of up to 400 MPa in a diesel engine

The study is driven by the trend of the rapidly growing injection pressure in diesel and gasoline engines with fuel injection into the combustion chamber. Experimental results were obtained by pouring fuel through a model nozzle and through the electrohydraulic diesel injectors. The paper describes reasons for the fuel significant heating at the injection and proposes its mathematical substantiation. For different tasks and fuels, three methods for the heating calculation during fuel injection at the ultra-high pressures were demonstrated. It was revealed that most important was fuel heating by the Joule-Thomson effect in the injector nozzle. Due to action of several heat release factors, fuel temperature could reach 240...260°C at the injection pressure of 350...400 MPa. The paper proposes most convenient relationships for computational analysis of the thermal conditions of the fuel supply process. Fuel heating assessment makes it possible to find the boundary conditions for calculating the intra-cylinder processes and the fuel outflow crisis at the ultra-high pressures.

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