HEAT EXCHANGE DURING CONDENSATION OF PURE OZONE-FRIENDLY REFRIGERANT R404A ON LONGITUDINALLY FINNERED HORIZONTAL PIPES

A method for conducting an experimental study of freon (R404A, etc.) condensation and their oil-freon mixtures on smooth and developed horizontal surfaces has been developed. A smooth and longitudinally finned surface with a trapezoidal fin shape is presented as the heat transfer surface under study. As a result of the conducted experimental studies of the condensation process of ozone-safe pure mixed refrigerant R404A on a longitudinally finned horizontal pipe with short fins in height, the hydrodynamic characteristics of the condensate (condensate film thickness along the fin height, film velocity and condensate flow rate, heat flux density and heat exchange process intensity) of the condensate film gravitationally flowing down the elements of the finned surface have been experimentally established. The dependencies obtained during the experimental studies (heat transfer coefficient on heat flux den-sity; film thickness on heat flux density; film thickness on temperature difference; heat transfer coefficient on temperature difference) show that the experimental data on heat transfer coefficients and condensate film thickness match with the data, calculated using the Nusselt formula.