Influence of Pipe Channel Inclination on Heat Exchange during Complete Condensation of R245fa Freon

Abstract

The design options for horizontal condensers for freon, petroleum products, and other chemicals are presented. The layout of such devices, in which air or water is used to cool steam, should preferably be carried out with minimal vertical dimensions. The process of condensation in horizontal and vertical pipes has been studied in a number of works; however, it is recommended in each specific case to have specific experimental data for engineering calculations. The article describes an experimental setup for studying the complete condensation of a promising freon, R245fa, in horizontal and inclined pipes. A copper pipe with grooves for installing thermocouples is built into the working section, which is cooled by water using the “pipe in pipe” scheme. Thermocouples are placed in the gap through which the cooling water flows to measure its temperature as it heats up, which allows determining the local value of the heat-transfer coefficients of the freon. As a result of experiments on the condensation of R245fa freon, the values of the average heat-transfer coefficient along the length of the pipe were obtained at different angles of inclination of the pipe and the mass velocity of the liquid, and it was established that, with an increase in inclination to 5°–10° to the horizon, the heat-transfer coefficient during condensation increases to the greatest extent. The distribution of the heat-transfer coefficient along the length of the pipe for complete condensation of R245fa was also obtained. At the initial stage, the value of the heat-transfer coefficient decreases rapidly and then stabilizes. The experimental results are useful for calculating heat-exchange devices, such as horizontal and slightly inclined air condensers for steam of various substances.