Experimental study of boiling on a modified surface of the evaporator of a heat pump unit

Аuthors

Ustinov D. A., Sidenkov D. V., Kuzma-Kichta Y. A.^*, Ustinov V. A., Ustinov A. K.

National Research University “Moscow Power Engineering Institute”, 14, Krasnokazarmennaya str., Moscow, 111250 Russia

*e-mail: kuzma@itf.mpei.ac.ru

Abstract

In this work, the boiling of Freon 134a on the modified surface of the evaporator of a heat pump unit was studied using optical laser methods for sensing a two-phase medium. Investiga-tion of interface oscillation during boiling was carried out by the method of laser diagnostics The analysis of the integrated values of the probe laser radiation intensity scattered by the vapor bubbles in the coolant flow based on the Mie scattering theory was completed. It became possi-ble to determine the average size of the vapor bubbles in the coolant flow. The time, correlation, and phase characteristics of the boiling process on a modified surface are obtained. The analysis of the time signal was carried out in the range up to 100 kHz. A comparison was made of the process of bubble boiling and a phase portrait of fluctuations in the intensity of the probe laser radiation using the Poincare section on a flat and modified heat exchange surfaces. It has been found that the modified surface generates ranges of steam bubbles 50 times larger than a flat surface. The materials obtained in this work indicate the chaotic nature of boiling.

Keywords:

boiling, modified surface, phase portrait, Poincare section, chaos.

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