Thermodynamic similar indicator diagrams of the heat engines Energy non-dimensional diagram of the heat engine closed cycle

Abstract

To provide an analysis of the thermodynamic processes occurring in a heat engine and its efficiency the indicator diagrams are used. The diagrams are constructed in the dimensional values of the parameters of the working fluid: volume, entropy, pressure, temperature, and other parameters. Exceptions include, for example, experimental studies and thermodynamic calculations performed, when designing a Laval nozzle for jet engines. These studies are based on the Similarity Theory. The paper shows graphoanalytical calculation of the efficiency of the idealized cycle of a heat engine in dimensionless working body parameters. Research methods using dimensionless parameters - similarity criteria are a characteristic feature of the Similarity Theory. In addition to the dimensionless indicator diagram, an energy dimensionless diagram of a circular closed loop of a heat engine was developed and described. The energy diagram depicts the thermodynamic processes of the exchange of heat and mechanical work between the working fluid and the environment in the dimensionless coordinates of heat and mechanical work. It is shown in the paper that the use of an energy dimensionless diagram is the simplest and most obvious graphoanalytical method for determining the efficiency of a heat engine. With regard to the analysis of the operation of a heat engine, the importance of using the Similarity Theory is determined by the fact that the only analytical, graphic or experimental study of a heat-specific engine with the least difficulties can be extended to the study of an infinite number of thermodynamically similar engines. For example, in the proposed work, the dimensionless calculation of the idealized Otto engine cycle is performed.