Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
ON THE CONJUGATED HEAT TRANSFER PROBLEMS INVOLVING FILM CONDENSATION IN THE PRESENCE OF A NONCONDENSABLE GAS
Submission Author:
Kleber Marques Lisbôa , RJ , Brazil
Co-Authors:
Karoline da Costa Rocha Fernandes Ferreira , Kleber Marques Lisbôa
Presenter: Karoline da Costa Rocha Fernandes Ferreira
doi://10.26678/ABCM.COBEM2021.COB2021-0010
Abstract
Full understanding of condensation heat transfer in its many facets has many potential benefits for industrial processes. Since the pioneering Nusselt model for film condensation, many extensions have been accomplished; most notably, the presence of noncondensable gases, even in small concentration, was determinated to severely diminish heat transfer rates and condensate output. In this work, we explore the effect of the coupling between natural convection of an air-water mixture, film condensation in the presence of noncondensables, conduction through a metallic plate, and single phase convection. For this purpose, the mass, species, momentum, and energy conservation principles are solved under the boundary layer hypothesis using Karman-Pohlhausen’s integral method; a simple one-dimensional conduction model is employed for the metallic wall and it is responsible for the coupling of the boundary layer equations stemming from filmwise condensation and single-phase forced convection. Furthermore, vapor superheating is also evaluated in the process. The influence of operational parameters, like flow rate and temperature, and main dimensions are investigated with the aim at maximizing the heat transfer rate and, consequently, the condensate productivity. In particular, the effects of the coolant and the associated non-uniformity of wall temperature and heat flux are analyzed carefully. The conclusions from this work are expected to influence developments on water desalination using membrane distillation, condenser design, nuclear reactor safety, among others.
Keywords
Film condensation, noncondensable gases, Conjugated heat transfer, Boundary Layer
