Dynamics of propagation of the self-sustaining evaporation front in a mixture of Freons under the natural convection conditions

Vladimir Zhukov,Mikhail Moiseev,S.V Alekseenko

doi:10.1051/matecconf/201711508007

Abstract

The results of experimental studies on dynamics of propagation of the self-sustaining evaporation front at nonstationary heat release are presented in the paper. The experiments were carried out in a large volume at liquid saturation temperature and subcooling on a horizontal cylindrical heat-releasing surface with the diameter of 3 mm under nonstationary heat release. Freons R21, R114 and their mixtures were used as the working liquid. The experiments carried out in the range of concentrations of high-volatile component 0 C C = 0.62). At a fixed value of the temperature head in the range of high values of Δ T , liquid subcooling relative to saturation line leads to a decrease in the velocity of evaporation front propagation.

Highlights

Nonstationary heat release at the local section of the heat exchanger can cause significant overheating of liquid heat carrier contacting with a heated wall, and formation and propagation of a continuous vapor film
The purpose of this work is the experimental study of evaporation front dynamics and development of hydrodynamic instability on the interface in freons R21, R114 and their mixtures
Dependences of evaporation front velocity Vfr on temperature head relative to saturation temperature 'T are shown in Fig. 1 for different molar concentrations C of high-volatile component R114

Summary

Introduction

Nonstationary heat release at the local section of the heat exchanger can cause significant overheating of liquid heat carrier contacting with a heated wall, and formation and propagation of a continuous vapor film. This effect can be observed in the systems of film and droplet irrigation and in a large volume. There has been a tendency to use the mixtures instead of a one-component fluid as a working medium in the refrigeration machines, heat pumps and thermal transformers. The purpose of this work is the experimental study of evaporation front dynamics and development of hydrodynamic instability on the interface in freons R21, R114 and their mixtures The ozone-safe non-azeotropic mixture refrigerants R32/R134a and R32/R152a are considered in [2] as well as heat transfer at boiling in horizontal tubes.

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Conclusion