Influence of Imperfections in Working Media on Diesel Engine Indicator Process

Abstract

Several improvements to the mathematical model for the indicator process in a diesel engine cylinder are proposed. The thermodynamic behavior of working media is described by the equation of state valid for real gases. Analytical mathematical dependencies between thermal parameters (pressure, temperature, volume) and caloric parameters (internal energy, enthalpy, specific heat capacities) have been obtained. These equations have been applied to the various products encountered during the burning of fuel and the gas mixture as a whole in the engine cylinder under conditions of high pressures. An improved mathematical model, based on the first law of thermodynamics, has been developed by taking into account imperfections in the working media that appear under high pressures. The numerical solution of the simultaneous differential equations is obtained by Runge–Kutta-type method. The mathematical model is then used to solve the desired practical problems in two different two-stroke turbo-charged engines: 8DKRN 74/160 and Sulzer-RLB66. Significant differences between the values calculated using ideal gas behavior and the real gas at high-pressure conditions have been found. The numerical experiments show that if the pressure is above 8 to 9 MPa, the imperfections in working medium must be taken into consideration. The results obtained from the mathematical dependencies of the caloric parameters can also be used to model energy conversion and combustion processes in other thermal machines such as advanced gas turbine engines with high-pressure ratios.