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Fixed Packed Bed Reactors in Reduced GravityWe present experimental data on flow pattern transitions, pressure drop and flow characteristics for cocurrent gas-liquid flow through packed columns in microgravity. The flow pattern transition data indicates that the pulse flow regime exists over a wider range of gas and liquid flow rates under microgravity conditions compared to 1-g and the widely used Talmor map in 1-g is not applicable for predicting the transition boundaries. A new transition criterion between bubble and pulse flow in microgravity is proposed and tested using the data. Since there is no static head in microgravity, the pressure drop measured is the true frictional pressure drop. The pressure drop data, which has much smaller scatter than most reported 1-g data clearly shows that capillary effects can enhance the pressure drop (especially in the bubble flow regime) as much as 200% compared to that predicted by the single phase Ergun equation. The pressure drop data are correlated in terms of a two-phase friction factor and its dependence on the gas and liquid Reynolds numbers and the Suratman number. The influence of gravity on the pulse amplitude and frequency is also discussed and compared to that under normal gravity conditions. Experimental work is planned to determine the gas-liquid mass transfer coefficients. Because of enhanced interfacial effects, we expect the gas-liquid transfer coefficients k(L)a and k(G)a (where a is the gas-liquid interfacial area) to be higher in microgravity than in normal gravity at the same flow conditions. This will be verified by gas absorption experiments, with and without reaction in the liquid phase, using oxygen, carbon dioxide, water and dilute aqueous amine solutions. The liquid-solid mass transfer coefficient will also be determined in the bubble as well as the pulse flow regimes using solid benzoic acid particles in the packing and measuring their rate of dissolution. The mass transfer coefficients in microgravity will be compared to those in normal gravity cocurrent flow to determine the mass transfer enhancement and propose new mass transfer correlations for two-phase gas-liquid flows through packed beds in microgravity.
Document ID
20040084203
Acquisition Source
Glenn Research Center
Document Type
Conference Paper
Authors
Motil, Brian J.
(NASA Glenn Research Center Cleveland, OH, United States)
Balakotaiah, Vemuri
(Houston Univ. TX, United States)
Kamotani, Yasuhiro
(Case Western Reserve Univ. Cleveland, OH, United States)
McCready, Mark J.
(Notre Dame Univ. IN, United States)
Date Acquired
August 21, 2013
Publication Date
June 1, 2004
Publication Information
Publication: Strategic Research to Enable NASA's Exploration Missions Conference
Subject Category
Fluid Mechanics And Thermodynamics
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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