hrvatski

Entropy analysis of adiabatic mixing of boiling liquid and superheated water vapour at equal pressures

The paper presents an analysis of entropy production at the adiabatic mixing of boiling water and superheated steam at constant pressure. The analysis is performed in dependence on the mass ratio of the boiling water for different pressures and temperatures of the superheated steam. The critical ratio of the boiling liquid in the mixture is defined, as the ratio at which the entropy production due to mixing is the largest. For the determination of the state parameters of the superheated steam, functional relationship describing the dependence between specific enthalpy and entropy to pressure and temperature were used in the analysis. The thermal state of the steam at the stationary point was determined using the Newton-Raphson iteration method. The dependence between the critical ratio, the according mixing temperature and the maximum entropy production on the mixing pressure is presented graphically, for the pressure range 0, 01 bar to 100 bar and steam superheat temperatures from 0 to 600 degrees C. Also the dependence on the entropy production on the boiling water mass ratio is graphically presented for some characteristic mixing pressures and temperatures. The obtained results give a complete insight into the entropy production, and therefore they present a good basis for the exergy (availability) analysis of more complicated processes in heat turbines.

adiabatic mixing; analysis; entropy; mixing; water; water vapour; heat water

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