Enhancement of the Processes of Transfer of Heat in a Diabatic Fractionating Column

Raising energy efficiency in the course of heat- and mass-transfer processes in column fractionating apparatuses is one topical problem of applied science and industry. Consideration has been given to a method of raising energy efficiency during the rectification of liquid mixtures due to the diabatization of the columns, that consists in installing built-in heat exchangers. The aim of the research is to determine thermal characteristics of the flow with the classical method of enhancement of heat transfer: finning the tubes externally. A mathematical description of the condensation of ascending vapor on the horizontal surface of finned tubes was developed. As a result of the research, the authors have determined heat outputs, temperatures of the heat-transfer agent at exit from a tubular dephlegmator, flow rates of cooling water, heat-transfer coefficients, linear coefficients of heat transfer, and thermal resistances of heat transfer with finned and smooth dephlegmator tubes on each tray in the rectifying section of the fractionating column. Results of theoretical investigations have shown that enhancing the processes of transfer of heat when the exterior tube surface is finned made it possible to increase heat fluxes in the dephlegmators to 3.74 times. It has been shown that the use of heat-transfer enhancers in the form of finning on the outside of dephlegmator tubes allows equalizing thermal heat-transfer resistances. It has been established that the investigated structure of a tubular dephlegmator with finned tubes makes it possible to raise the Murphree efficiency of the valve tray by 7.7%.