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Title: A Novel Absorption Cycle for Combined Water Heating, Dehumidification, and Evaporative Cooling

Abstract

In this study, development of a novel system for combined water heating, dehumidification, and space evaporative cooling is discussed. Ambient water vapor is used as a working fluid in an open system. First, water vapor is absorbed from an air stream into an absorbent solution. The latent heat of absorption is transferred into the process water that cools the absorber. The solution is then regenerated in the desorber, where it is heated by a heating fluid. The water vapor generated in the desorber is condensed and its heat of phase change is transferred to the process water in the condenser. The condensed water can then be used in an evaporative cooling process to cool the dehumidified air exiting the absorber, or it can be drained if primarily dehumidification is desired. Essentially, this open absorption cycle collects space heat and transfers it to process water. This technology is enabled by a membrane-based absorption/desorption process in which the absorbent is constrained by hydrophobic vapor-permeable membranes. Constraining the absorbent film has enabled fabrication of the absorber and desorber in a plate-and-frame configuration. An air stream can flow against the membrane at high speed without entraining the absorbent, which is a challenge in conventionalmore » dehumidifiers. Furthermore, the absorption and desorption rates of an absorbent constrained by a membrane are greatly enhanced. Isfahani and Moghaddam (Int. J. Heat Mass Transfer, 2013) demonstrated absorption rates of up to 0.008 kg/m2s in a membrane-based absorber and Isfahani et al. (Int. J. Multiphase Flow, 2013) have reported a desorption rate of 0.01 kg/m2s in a membrane-based desorber. The membrane-based architecture also enables economical small-scale systems, novel cycle configurations, and high efficiencies. The absorber, solution heat exchanger, and desorber are fabricated on a single metal sheet. In addition to the open arrangement and membrane-based architecture, another novel feature of the cycle is recovery of the solution heat energy exiting the desorber by process water (a process-solution heat exchanger ) rather than the absorber exiting solution (the conventional solution heat exchanger ). This approach has enabled heating the process water from an inlet temperature of 15 C to 57 C (conforming to the DOE water heater test standard) and interfacing the process water with absorbent on the opposite side of a single metal sheet encompassing the absorber, process-solution heat exchanger, and desorber. The system under development has a 3.2 kW water heating capacity and a target thermal coefficient of performance (COP) of 1.6.« less

Authors:
 [1];  [2];  [2];  [1]
  1. University of Florida, Gainesville
  2. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Building Technologies Research and Integration Center (BTRIC)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
1150906
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Conference
Resource Relation:
Conference: International Soprtion Heat Pump Conference, Washington, DC, USA, 20140331, 20140403
Country of Publication:
United States
Language:
English
Subject:
Membrane; Absorption Heat Pump; Water Heater

Citation Formats

CHUGH, Devesh, Gluesenkamp, Kyle R, Abdelaziz, Omar, and Moghaddam, Saeed. A Novel Absorption Cycle for Combined Water Heating, Dehumidification, and Evaporative Cooling. United States: N. p., 2014. Web.
CHUGH, Devesh, Gluesenkamp, Kyle R, Abdelaziz, Omar, & Moghaddam, Saeed. A Novel Absorption Cycle for Combined Water Heating, Dehumidification, and Evaporative Cooling. United States.
CHUGH, Devesh, Gluesenkamp, Kyle R, Abdelaziz, Omar, and Moghaddam, Saeed. Wed . "A Novel Absorption Cycle for Combined Water Heating, Dehumidification, and Evaporative Cooling". United States.
@article{osti_1150906,
title = {A Novel Absorption Cycle for Combined Water Heating, Dehumidification, and Evaporative Cooling},
author = {CHUGH, Devesh and Gluesenkamp, Kyle R and Abdelaziz, Omar and Moghaddam, Saeed},
abstractNote = {In this study, development of a novel system for combined water heating, dehumidification, and space evaporative cooling is discussed. Ambient water vapor is used as a working fluid in an open system. First, water vapor is absorbed from an air stream into an absorbent solution. The latent heat of absorption is transferred into the process water that cools the absorber. The solution is then regenerated in the desorber, where it is heated by a heating fluid. The water vapor generated in the desorber is condensed and its heat of phase change is transferred to the process water in the condenser. The condensed water can then be used in an evaporative cooling process to cool the dehumidified air exiting the absorber, or it can be drained if primarily dehumidification is desired. Essentially, this open absorption cycle collects space heat and transfers it to process water. This technology is enabled by a membrane-based absorption/desorption process in which the absorbent is constrained by hydrophobic vapor-permeable membranes. Constraining the absorbent film has enabled fabrication of the absorber and desorber in a plate-and-frame configuration. An air stream can flow against the membrane at high speed without entraining the absorbent, which is a challenge in conventional dehumidifiers. Furthermore, the absorption and desorption rates of an absorbent constrained by a membrane are greatly enhanced. Isfahani and Moghaddam (Int. J. Heat Mass Transfer, 2013) demonstrated absorption rates of up to 0.008 kg/m2s in a membrane-based absorber and Isfahani et al. (Int. J. Multiphase Flow, 2013) have reported a desorption rate of 0.01 kg/m2s in a membrane-based desorber. The membrane-based architecture also enables economical small-scale systems, novel cycle configurations, and high efficiencies. The absorber, solution heat exchanger, and desorber are fabricated on a single metal sheet. In addition to the open arrangement and membrane-based architecture, another novel feature of the cycle is recovery of the solution heat energy exiting the desorber by process water (a process-solution heat exchanger ) rather than the absorber exiting solution (the conventional solution heat exchanger ). This approach has enabled heating the process water from an inlet temperature of 15 C to 57 C (conforming to the DOE water heater test standard) and interfacing the process water with absorbent on the opposite side of a single metal sheet encompassing the absorber, process-solution heat exchanger, and desorber. The system under development has a 3.2 kW water heating capacity and a target thermal coefficient of performance (COP) of 1.6.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2014},
month = {1}
}

Conference:
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