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ISSN Online: 2377-424X

ISBN CD: 1-56700-226-9

ISBN Online: 1-56700-225-0

International Heat Transfer Conference 13
August, 13-18, 2006, Sydney, Australia

A STUDY OF HEAT AND MASS TRANSFER IN FALLING FILMS OF FILM-INVERTING ABSORBERS

Get access (open in a dialog) DOI: 10.1615/IHTC13.p12.490
12 pages

Resumo

With a view to developing a high-performance absorber of absorption refrigeration systems, a novel absorber-concept called “Film-inverting absorber” is introduced in the present study. The concept of this new absorber is based on the fluid flow characteristics of the falling film and the thermodynamic aspect of the absorption process. In this design, the falling film is inverted repeatedly as it flows over a series of horizontal tubes. The performance of the film-inverting absorber is analyzed theoretically using a detailed numerical model in which the conservation equations of mass, momentum and energy were solved simultaneously with appropriate boundary conditions. The computed mass flux of water vapor and the heat and mass transfer coefficients of the film-inverting absorber are compared with that of a continuous film absorber of the same total length under the same operating conditions. The simulation results show that the mass flux of water vapor could be improved significantly in the film-inverting absorber. The performance of the film-inverting absorber is investigated experimentally for different spray density of solution and coolant inlet temperature. A simplified lumped model has been developed to extract the heat and mass transfer coefficients of the film from the experimental data. This model can be used to design film-inverting absorber. The average transfer coefficients determined using the detailed and the simplified lumped model are in good agreement. The average heat and mass transfer coefficients for the film-inverting absorber are significantly larger than the corresponding transfer coefficients for a conventional round-tube absorber.