In this paper, the local and average heat transfer during the condensation of water vapor on a horizontal copper pipe without and with a hydrophobic coating was investigated in conditions of gas content. The coating is formed by a combined structure consisting of a layer of carbon nanoparticles, microroughness and silicone oil. Microroughness was formed by abrasive sand blasting. The deposition of a layer of carbon nanoparticles led to an increase in the contact angle up to 160 degrees. The study of condensation was carried out on an experimental setup, which consisted of the main and auxiliary circuits. A copper pipe with a diameter of 12 mm and a heater were installed in the working chamber. Descriptions of the experimental setup and research methodology are given. To determine the average heat transfer coefficient during condensation on the pipe, the heat load in the working area and the temperature difference are found. The heat power supplied to the water that cools the working section was determined by the difference in the temperatures of the coolant at its inlet and outlet. Before carrying out the experiments, the heat losses were calibrated. The temperature difference in the boundary layer on the liquid side is determined using the Petukhov B.S. formula for the heat transfer coefficient. for fluid flow in the channel. Local and average heat transfer during condensation on a water vapor pipe was studied in the range of temperature difference from 10 to 40 ℃, gas rcontent fom 20 to 80% and pressure from 0.009 to 0.1 MPa. Platinum resistance thermometers and thermocouples were used to determine the wall temperature. When measuring local heat fluxes during condensation on a horizontal pipe, a gradient heat flux sensor based on a bismuth single crystal was used. Experimental data and dependencies are obtained for calculating the average and local heat transfer during the condensation of water vapor on a horizontal pipe without coating and with a developed coating under the studied conditions. The developed coating leads to an increase in the average heat transfer during condensation on a horizontal pipe by a factor of two.
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