Experimental study of heat transfer during boiling in a thin layer of liquid on surfaces with structured porous coatings

Abstract

The paper presents the results of the study of evaporation and boiling in a thin horizontal layer of liquid on microstructured surfaces in a wide range of changes in pressure. It is found that the thermal conductivity of materials of microstructured surfaces significantly affects the mechanism of steam removal from the pores and circulation of liquid along the heat transfer surface. It is determined that the pressure change leads to three regimes of heat transfer: evaporation, transition regime, and bubble boiling. The lowest values of the heat transfer coefficients and CHF were obtained in the transition regime; the highest ones were obtained in the bubble regime on both surfaces. Due to the higher thermal conductivity, the higher heat transfer coefficients and CHF were obtained on the bronze coating than on stainless steel over the entire pressure range.