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Performance evaluation of a membrane-based flat-plate heat and mass exchanger used for liquid desiccant regeneration

Bai, Hongyu; Zhu, Jie; Chen, Ziwei; Chu, Junze; Liu, Yiwen

Authors

Hongyu Bai

Junze Chu Junze.CHU@nottingham.ac.uk

Yiwen Liu



Abstract

Liquid desiccant dehumidification system has gained much progress recently for its considerable energy saving potential without liquid water condensation. Within the system, regeneration is of great importance since diluted desiccant solution after dehumidification needs to be re-concentrated. The operational characteristics of a membrane-based flat-plate heat and mass exchanger used for liquid desiccant regeneration are investigated in this study. The liquid desiccant and air are in a cross-flow arrangement, and separated by semi-permeable membranes to avoid carry-over problem. The regeneration performance is examined by numerical simulation and experimental test. Solution side effectiveness, temperature decrease rate (TDR) and moisture flux rate (MFR) are applied to evaluate heat and mass transfer in the regenerator. Effects of main operating parameters are assessed, which include dimensionless parameters (i.e. number of heat transfer units NTU and solution to air mass flow rate ratio m∗), solution inlet properties (i.e. temperature T sol,in and concentration C sol,in) and air inlet conditions (i.e. temperature T air,in and humidity ratio air,in). It is found that m∗ and NTU are two of the most important parameters and their effects on the regeneration performance are interacted with each other. There is hardly benefit to the performance improvement by increasing NTU at low m∗ or increasing m∗ at low NTU. Even though the regeneration performance can be improved by increasing m∗ and NTU, its improvement gradient is limited when m∗ and NTU exceed 2 and 4 respectively. It is also found that increasing olution inlet temperature is an effective approach to enhance the regeneration performance, while air inlet temperature and humidity ratio have negligible effects on it.

Citation

Bai, H., Zhu, J., Chen, Z., Chu, J., & Liu, Y. (2018). Performance evaluation of a membrane-based flat-plate heat and mass exchanger used for liquid desiccant regeneration. Applied Thermal Engineering, 139, https://doi.org/10.1016/j.applthermaleng.2018.05.011

Journal Article Type Article
Acceptance Date May 5, 2018
Online Publication Date May 9, 2018
Publication Date Jul 5, 2018
Deposit Date May 8, 2018
Publicly Available Date May 10, 2019
Journal Applied Thermal Engineering
Print ISSN 1359-4311
Electronic ISSN 1873-5606
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 139
DOI https://doi.org/10.1016/j.applthermaleng.2018.05.011
Keywords liquid desiccant, regeneration, numerical modelling, membrane-based flat-plate exchange
Public URL http://eprints.nottingham.ac.uk/id/eprint/51633
Publisher URL https://www.sciencedirect.com/science/article/pii/S1359431118315424?via%3Dihub
Copyright Statement Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by-nc-nd/4.0

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Copyright Statement
Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by-nc-nd/4.0





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