Effect of Multi-Irreversibilities on the Performance Characteristics of an Irreversible Air-Standard Diesel Heat Engine

An irreversible model of the air-standard Diesel heat engine cycle is established, in which the primary irreversibilities, such as the heat leak loss through the cylinder wall, friction loss, internal irreversibility and temperature-variable heat capacities, are considered. The analytic expressions of the power output and efficiency are derived. The relations between the power output and the ratio of the highest to the lowest pressure of the working fluid, between the efficiency and the ratio of the highest to the lowest pressure of the working fluid, as well as the optimal relation between the power output and the efficiency of the Diesel cycle are shown by numerical example. Moreover, the influence of these primary irreversible factors on the performance parameters of the Diesel heat engine is discussed. The results obtained here may provide some significant guidelines for the optimal design and operation of the practical Diesel heat engines.