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Annular-finned sorption bed heat exchanger design for adsorption heat pump optimization.

Author(s) : RAYMOND A., GARIMELLA S.

Summary

Adsorbent temperature control is critical in adsorption heat pumps. During both adsorption and desorption, the thermal conductance of the sorption bed should be large to yield the greatest possible change in equilibrium uptake, thus maximizing refrigerant throughput and cooling duty. While thermal control is critical, the transient nature of adsorption heat pumps complicates sorption bed design. In steady thermal systems like absorption heat pumps, extended surfaces may be used liberally to intensify heat transfer, notwithstanding increased mass and cost. Adsorption heat pumps are subject to the same cost and mass constraints, but because the sorption bed is thermally cycled, any extended surfaces will detrimentally affect the coefficient of performance as energy stored in the inert heat exchanger during desorption will be discarded during the subsequent pre-cooling and adsorption stages. The annular finned geometry, which appears frequently in commercial and research adsorption heat pumps, is analyzed in this work. A thermodynamic model of a non-recuperative heat pump is developed and the effects of fin height, fin pitch and other parameters on the coefficient of performance are investigated Both silica gel-water and activated carbon fiber (ACF)-ethanol working pairs are investigated, and it is found that the heat exchanger geometry that yields a desirable balance of thermal conductance and COP is significantly different for these two working pairs as a result of their different densities, wall contact resistances and effective conductivities.

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Pages: 453-465

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Details

  • Original title: Annular-finned sorption bed heat exchanger design for adsorption heat pump optimization.
  • Record ID : 30001233
  • Languages: English
  • Source: Sources/sinks Alternative to the Outside Air for Heat Pump and Air-conditioning Techniques (Alternative Sources - AS), Padua, Italy, April 5-7, 2011. / International Sorption Heat Pump Conference (ISHPC11), Padua, Italy, April 6-8, 2011.
  • Publication date: 2011/04/06

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