The Processes of Vaporization in the Porous Structures Working with the Excess of Liquid

Abstract

The processes of vaporization in porous structures, working with the excess of liquid are investigated. With regard to the thermal power plants new porous cooling system is proposed and investigated, in which the supply of coolant is conducted by the combined action of gravity and capillary forces. The cooling surface is made of stainless steel, brass, copper, bronze, nickel, alundum, and glass, with wall thickness of 0.0.5.10(-3)-2.10(-3) m. Visualizations of the processes of vaporization were carried out using holographic interferometry with the laser system and high speed camera. The operating conditions of the experiments were: water pressures 0.01-10 MPa, the temperature difference of subcooling 0-20 degrees C, an excess of liquid 1-14 of the steam flow, the heat load 1.10(4)-60.10(4) W/m(2), the temperature difference 1-60 degrees C, and orientation of the system +/- 0-+/- 90 degrees. Studies have revealed three areas of liquid vaporization process (transitional, developed, and crisis). The impact of operating and design parameters on the integrated and thermal hydraulic characteristics was defined. The optimum (minimum) flow rate of cooling fluid and the most effective type of mesh porous structure were also defined.