Generalized component design model by combined heat and mass transfer analysis in NH3-H2O absorption heat pump systems

Yong Tae Kang, Weibo Chen, Richard N. Christensen

Research output: Contribution to journalConference articlepeer-review

34 Citations (Scopus)


This paper develops a generalized design model using combined heat and mass transfer analysis for components used in absorption heat pump systems. The model can be applied to the design of an absorber, desorber, rectifier, condenser, or evaporator in NH3-H2O absorption heat pump systems. The physical significance of the ammonia composition in the absorbing/desorbing vapor, z, was studied. A composition map was generated by solving the diffusion and mass balance equations simultaneously for each component. It was found that the ammonia concentration in the absorbing/desorbing vapor cannot be found using only the liquid concentration or vapor concentration but must be determined using combined heat and mass transfer analysis. The composition of ammonia, z, should be z < x1 for the rectifier, x1 < z < xvb for condensers, xvb < z for absorbers, xvi < z for desorbers, and x1 < z < xvi for evaporators. The results show that the mass transfer of ammonia and water is in the same direction for the rectifier, evaporator, and condenser, while it may be in the opposite direction for the absorber and desorber. The generalized design model developed in this paper can be used to investigate the effects of variable parameters, such as the heat transfer coefficient in each region, the vapor velocity, and the temperature deviation from the equilibrium, on the performance of each component.

Original languageEnglish
Pages (from-to)444-453
Number of pages10
JournalASHRAE Transactions
Issue number1
Publication statusPublished - 1997
Externally publishedYes
EventProceedings of the 1997 ASHRAE Winter Meeting - Philadelphia, PA, USA
Duration: 1997 Jan 261997 Jan 29

ASJC Scopus subject areas

  • Building and Construction
  • Mechanical Engineering


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