engleski

Transfer from Carnot to Lorenz Process Using Zeotropic Mixtures

The paper refers to the thermodynamic efficiency of the left hand cooling-heating process operating with a zeotropic mixture R407C that is compared to the process operating with a pure refrigerant R22. The measurements are performed on the experimental refrigerating system that enables operation according to Lorenz (zeotropic mixture application) and Carnot process (pure refrigerant application). The zeotropic mixture, during evaporation or condensation, changes temperature and there is a possibility to match temperature change with temperature decrease of a cooled medium in the evaporator, and temperature increase of the cooling water in the condenser. But, this is possible only in the counterflow heat exchangers. Obtained results show that the refrigerant R407C is a good substitute for the refrigerant R22 at higher evaporation temperatures. Although theoretical analysis has led to the assumption that R407C will increase efficiency compared to R22, the experimental results did not confirm it. The reasons are lower heat transfer coefficients in the process when refrigerant R407C is used.

zeotropic mixtures; Lorenz process; thermodynamic efficiency

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