Cooling by a Dispersed Flow Performing a Phase Transition of a Modifies Surface

Abstract

Cooling of a modified surface by a dispersed flow of distilled water has been investigated experimentally, and the results have been compared with cooling of an unmodified surface. The modification of the heat-exchange surface of the copper working region has been performed by processing with a high-energy electron beam; as a result, a unique microporous surface has been obtained. The macrograph of the modified surface has been obtained and profiles have been measured using a profile meter. Four series of experiments for various heat carrier parameters have been performed for the modified and unmodified surfaces. The excess pressure of the heat carrier at the sprayer input was (4–14) × 10⁵ Pa, the mass flow rate of the heat carrier (distilled water) was (2.1–4.3) × 10^–3 kg/s, and the spraying density varied in the limits (3.0–6.1) kg/(m² s). The variations of the heat flux densities for these surfaces were compared. The convective component and the component of the phase transition of the removed heat flow during cooling the surface by a dispersed flow were estimated, and the conclusion was made concerning the key contribution of the phase transition to this process was made. The amount of evaporated liquid for the considered cooling modes were compared, and the dependence of this quantity on the heat flux density was obtained. The maximal heat flux density during the cooling of the surface by a dispersed flow attained 8.5 MW/m².