Use this URL to cite or link to this record in EThOS: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.817590
Title: Heat and mass exchanger design for inter-seasonal liquid absorption heat storage
Author: Fumey, Benjamin
ISNI:       0000 0004 9357 6681
Awarding Body: Ulster University
Current Institution: Ulster University
Date of Award: 2020
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Abstract:
Sorption heat storage gives perspective for renewable space heating in buildings. Benefits put forth are, loss free storage over time and increased energy density exceeding that of hot water storage. Critical performance parameters in this application are: gross temperature lift, volumetric power density and volumetric energy density. Heat and mass transport in light of these parameters is a challenge holding back this technology from commercialisation. In this thesis, an effective heat and mass exchanger design for liquid absorption heat storage with aqueous sodium hydroxide for compact inter-seasonal heat storage is presented. In this work, global sorption heat storage performance parameters and operating temperatures were defined, followed by a categorisation of sorption heat storage process types and analysis of performance potential. The closed transported process with single pass and true counterflow was found favourable. Mass transport was recognised as the dominant boundary in this process, and detailed analysis from milligram to kilogram scale was undertaken. Still film absorption measurements showed the need for extended exposure time for sufficient absorbent exchange (energy capacity). Hereto a novel vertically installed spiral finned tube heat and mass exchanger was developed. Highly temporally and spatially resolved analysis of the mass diffusion in thin absorbent film as present on the spiral finned tube was undertaken with Raman spectroscopy. Mass diffusion in the film was found to be the limiting parameter, indicating that there is potential for improved mass flux through mixing. Visual evaluation of absorption and mass transport was carried out with neutron imaging. In this approach, strong concentration stratification due to buoyancy force was detected. A method towards engaging this buoyancy movement for increased absorption kinetics was found by flooded spiral finned heat and mass exchanger. The functionality of this advanced approach was extensively examined on the lab test bench and good performance was found.
Supervisor: Griffiths, Philip ; Hewitt, Neil Sponsor: Swiss Innovation Agency Innosuisse ; Swiss Federal Office of Energy (SFOE)
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.817590  DOI: Not available
Keywords: Sorption heat storage for buildings ; Performance parameters ; Application specific testing ; Spiral finned heat and mass exchanger ; Mass transport ; Absorbent mixing
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