The Experimental Analysis of Local Heat and Mass Transfer Data for Vertical Falling Film Absorption

Conference · Sun Nov 14 04:00:00 EST 1999

OSTI ID:9280

Keyhani, M ^[1]; Miller, W A

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1. ORNL

In pure heat transfer, specifications of effectiveness, fluid properties, and flows enable calculation of the heat exchanger area. In the case of falling film absorption, a simultaneous heat and mass transfer governs the performance of the absorber. The exchange of mass across the liquid-vapor interface involves the generation of heat. The heat effects associated with the mass exchange increase the temperature, which affects the equilibrium state of the pressure and composition and in turn affects the mass. The falling film flow rate coupled to the physical properties of kinematic viscosity and surface tension govern the flow regime of a vertical falling film. Wavy-laminar, roll-wave laminar, and turbulent flows will develop convective contributions that can enhance the transfer of mass into the film. The combined interaction of all these factors makes the absorption process very difficult to analyze and predict. A study of simultaneous heat and mass transfer was therefore conduct ed on a vertical falling film absorber to better understand the mechanisms driving the heat and mass transfer processes. Falling films are characteristically unstable, and a wavy-laminar flow was observed during the experimental study. The wavy flow further complicates the problem; therefore, only limited information is known about the temperature and concentration profiles along the length of the absorber that describe the local heat and mass transfer rates.

• Research Organization: Oak Ridge National Lab., TN (US)
• Sponsoring Organization: Gas Research Institute; USDOE Office of Science (US)
• DOE Contract Number: AC05-96OR22464
• OSTI ID: 9280
• Report Number(s): ORNL/CP-103985; EC 12 02 00 0; EC 12 02 00 0
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
ABSORPTION
FALLING FILM ABSORPTION
FILM FLOW
HEAT EXCHANGERS
HEAT TRANSFER
MASS TRANSFER
PHYSICAL PROPERTIES
SURFACE TENSION
TEMPERATURE DEPENDENCE
TURBULENT FLOW