engleski

Entropy generation and exergy efficiency in adiabatic mixing of nitrogen and oxygen streams of different temperatures and environmental pressures

The paper presents a non-dimensional model of entropy generation and exergy efficiency in the adiabatic mixing of a nitrogen stream and an oxygen stream having different temperatures and the environmental pressure. The resulting mixture has the same, i.e. environmental, pressure. Non-dimensional variables in the model represent the ratio of thermodynamic stream temperatures u, the ratio between the thermodynamic temperature of one stream and the environmental temperature u1, and the mole fraction y1 of one of the streams. The model comprises the irreversibility due to different temperatures of streams, due to the mixing of different gases, while exergies of streams comprise also their mole fractions in the ambient air (atmosphere). In this respect, the model takes the standard values of mole fractions of oxygen and nitrogen of yO2 = 0.21 and yN2 = 0.79. The values of stream mole fractions at which maximum values of entropy generation and minimum values of exergy efficiencies occur are given. Calculation results are given in respective diagrams.

analytic model; entropy generation; exergy efficiency; mixing of nitrogen and oxygen streams

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