Building and using temperature chart to determine thermodynamic efficiency of ship steam-compression heat transformers

The article highlights the method of constructing a temperature chart, which allows evaluating the thermodynamic efficiency of ship combined thermal transformers. Refrigerants R134a, R717 were selected as the analyzed refrigerants in the construction of the temperature chart. The results of calculating the degree of thermodynamic perfection of single-stage combined thermal transformers without a regenerative heat exchanger are presented. The dependence of changing thermodynamic perfection on the melting and condensation temperature is given. The separation and classification of the areas of this dependence is proposed. The process of determining and constructing the characteristics that set the limit of application of the considered thermal transformers is described. The values influencing the position of the selected regions on the temperature chart are revealed. For the selected refrigerants there have been presented the dependences for correcting position of the areas depending on the amount of overheating, degree of supercooling and temperature difference between the boiling point and the temperature of low-potential heat source. The application of the temperature chart is analyzed under the following initial data: refrigerant R134a; condensation temperature 40°C; boiling point –20°C; ambient temperature 20°C; steam overheating 20 K; supercooling of the liquid 8 K; temperature difference between the low-grade heat source and the boiling point 8 K. The graph illustrates an example of using a temperature chart to determine the possibility of using combined heat transformers with specified parameters on the refrigerant R134a. Equations are derived for correcting the position of the lines of temperature charts for refrigerants permitted for the ship power plants.