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Design of a compact absorber with a hydrophobic membrane contactor
at the liquid–vapor interface for lithium bromide–water absorption chillers

Research Authors
Ahmed Hamza H. Ali
Research Member
Research Year
2010
Research Journal
Applied Energy
Research Vol
vol 87 - no 4
Research Rank
1
Research_Pages
1112-1121
Research Abstract

In this study, design of a compact plates-and-frames absorber possessing a hydrophobic microporous
membrane contactor at the aqueous solution–water vapor interface is performed analytically. The absorber
is a component of a 5 kW cooling capacity single-effect lithium bromide–water absorption chiller that
incorporates a hot water thermally driven generator and a water-cooled absorber and condenser. Good
agreement prevailed for the analytically evaluated water vapor mass transfer flux and aqueous solution
outlet temperature when compared with measured values at similar operating conditions. At design
point conditions, the main design parameters obtained are a membrane contactor area of 6.06 m2, a ratio
of the mass transfer area to absorber net volume (Am=Vnet) of 130.1(m2/m3), and ratio of the membrane
area (mass transfer area) in this design configuration to the area required for heat transfer is 1.162,
respectively. The results clearly indicate that the aqueous solution channel thickness is the most significant
design parameter that affects the absorber size compactness; the thinner the thickness of the solution
channel, the higher the ratio (Am=Vnet ). The results also show the countercurrent refrigerant flow
with the aqueous solution has positive effects on the absorber size compactness.