Modeling of a Membrane-Based Absorption Heat Pump

Jason Woods, John Pellegrino, Eric Kozubal, Steve Slayzak, Jay Burch

Research output: Contribution to journalArticlepeer-review

36 Scopus Citations

Abstract

In this paper, a membrane heat pump is proposed and analyzed. Fundamentally, the proposed heat pump consists of an aqueous CaCl2 solution flow separated from a water flow by a vapor-permeable membrane. The low activity of the solution results in a net flux of water vapor across the membrane, which heats the solution stream and cools the water stream. This mechanism upgrades water-side low-temperature heat to solution-side high-temperature heat, creating a "temperature lift." The modeling results show that using two membranes and an air gap instead of a single membrane increases the temperature lift by 185%. The model predicts temperature lifts for the air-gap design of 24, 16, and 6 °C for inlet temperatures of 55, 35, and 15 °C, respectively. Membranes with lower thermal conductivities and higher porosities improve the performance of single-membrane designs while thinner membranes improve the performance of air-gap designs. This device can be used with a solar heating system which already uses concentrated salt solutions for liquid-desiccant cooling.

Original languageAmerican English
Pages (from-to)113-124
Number of pages12
JournalJournal of Membrane Science
Volume337
Issue number1-2
DOIs
StatePublished - 2009

NREL Publication Number

  • NREL/JA-550-46281

Keywords

  • Desiccant
  • Energy storage
  • Heat and mass transfer modeling
  • Heat pump
  • Membrane distillation

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