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The synergism between heat and mass transfer additive and advanced surfaces in aqueous lithium bromide horizontal tube absorbers.

Author(s) : MILLER W. A.

Summary

A mini absorber test stand was used to test smooth tubes and a variety of advanced tube surfaces placed horizontally in a single-row copper tube bundle. Manufacturers of absorption chillers add small quantities of a heat and mass transfer additive to improve the performance of the absorbers. The additive causes surface stirring which enhances the transport of absorbate into the bulk of the film (Marangoni effect). Experiments were conducted over the operating conditions of 6.5 mm Hg absorber pressure, coolant temperatures ranging from 20 to 35 °C and lithium bromide mass fractions ranging from 0.60 through 0.62. Tube spacing and presence of additive were tested. The mechanical mixing of the advanced surfaces increased the mass transfer to about 75% of that observed on a smooth tube bundle, tested with heat and mass transfer additive. Testing with heat and mass transfer additive and advanced surfaces demonstrated a synergistic effect which doubled the mass absorbed from that observed with only the advanced surface. The overall film-side heat transfer coefficient for the advanced tube bundles doubled with the addition of 500-wppm of 2-ethyl-1-hexanol.

Details

  • Original title: The synergism between heat and mass transfer additive and advanced surfaces in aqueous lithium bromide horizontal tube absorbers.
  • Record ID : 2000-2932
  • Languages: English
  • Source: Proceedings of the International Sorption Heat Pump Conference.
  • Publication date: 1999/03/24
  • Document available for consultation in the library of the IIR headquarters only.

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