Experimental study on the droplet formation around pins of different geometry for the design of a compact falling-droplet absorber

Absorber downsizing for the development of compact absorption chillers is a known challenge of this type of refrigerator. Past studies have revealed how a droplet flow regime can increase the interface area and enhance absorption rates, especially during the droplet formation. This study proposes a...

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Main Authors: Cola, Fabrizio, Romagnoli, Alessandro, Hey, Jonathan
Other Authors: School of Mechanical and Aerospace Engineering
Format: Journal Article
Language:English
Published: 2020
Subjects:
Online Access:https://hdl.handle.net/10356/139435
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author Cola, Fabrizio
Romagnoli, Alessandro
Hey, Jonathan
author2 School of Mechanical and Aerospace Engineering
author_facet School of Mechanical and Aerospace Engineering
Cola, Fabrizio
Romagnoli, Alessandro
Hey, Jonathan
author_sort Cola, Fabrizio
collection NTU
description Absorber downsizing for the development of compact absorption chillers is a known challenge of this type of refrigerator. Past studies have revealed how a droplet flow regime can increase the interface area and enhance absorption rates, especially during the droplet formation. This study proposes a space-efficient design for an adiabatic absorber based on a bank of solid pins coupled with a droplet flow regime. Manufacturing through 3D printing technique is used to study the effect of different fin shapes during droplet formation. Droplet behavior is firstly studied analytically through a variational approach. Experiments on pure water are then carried out to validate the model and produce design guidelines for a H2O-LiBr absorber. Results show that the analytical model is more accurate in the regions close to the droplet bottom. The rhomboidal geometry with 120° returned the smallest droplet volume without allowing coalescence of more droplets, ensuring the maintenance of droplet flow and a high surface area for mass transfer. Disturbances in the droplet profiles were observed, caused by the pin-droplet interaction. A map has been then created to allow a quick sizing of the absorber and find its main geometrical and operational features.
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spelling ntu-10356/1394352021-01-08T02:58:13Z Experimental study on the droplet formation around pins of different geometry for the design of a compact falling-droplet absorber Cola, Fabrizio Romagnoli, Alessandro Hey, Jonathan School of Mechanical and Aerospace Engineering Energy Research Institute @ NTU (ERI@N) Engineering::Mechanical engineering Droplet Absorber Absorber downsizing for the development of compact absorption chillers is a known challenge of this type of refrigerator. Past studies have revealed how a droplet flow regime can increase the interface area and enhance absorption rates, especially during the droplet formation. This study proposes a space-efficient design for an adiabatic absorber based on a bank of solid pins coupled with a droplet flow regime. Manufacturing through 3D printing technique is used to study the effect of different fin shapes during droplet formation. Droplet behavior is firstly studied analytically through a variational approach. Experiments on pure water are then carried out to validate the model and produce design guidelines for a H2O-LiBr absorber. Results show that the analytical model is more accurate in the regions close to the droplet bottom. The rhomboidal geometry with 120° returned the smallest droplet volume without allowing coalescence of more droplets, ensuring the maintenance of droplet flow and a high surface area for mass transfer. Disturbances in the droplet profiles were observed, caused by the pin-droplet interaction. A map has been then created to allow a quick sizing of the absorber and find its main geometrical and operational features. 2020-05-19T08:02:25Z 2020-05-19T08:02:25Z 2018 Journal Article Cola, F., Romagnoli, A., & Hey, J. (2018). Experimental study on the droplet formation around pins of different geometry for the design of a compact falling-droplet absorber. Heat and Mass Transfer, 54, 3599-3616. doi:10.1007/s00231-018-2381-8 0947-7411 https://hdl.handle.net/10356/139435 10.1007/s00231-018-2381-8 2-s2.0-85047665909 54 3599 3616 en Heat and Mass Transfer © 2018 Springer-Verlag GmbH Germany, part of Springer Nature. All rights reserved. This paper was published in Heat and Mass Transfer and is made available with permission of Springer-Verlag GmbH Germany, part of Springer Nature.
spellingShingle Engineering::Mechanical engineering
Droplet
Absorber
Cola, Fabrizio
Romagnoli, Alessandro
Hey, Jonathan
Experimental study on the droplet formation around pins of different geometry for the design of a compact falling-droplet absorber
title Experimental study on the droplet formation around pins of different geometry for the design of a compact falling-droplet absorber
title_full Experimental study on the droplet formation around pins of different geometry for the design of a compact falling-droplet absorber
title_fullStr Experimental study on the droplet formation around pins of different geometry for the design of a compact falling-droplet absorber
title_full_unstemmed Experimental study on the droplet formation around pins of different geometry for the design of a compact falling-droplet absorber
title_short Experimental study on the droplet formation around pins of different geometry for the design of a compact falling-droplet absorber
title_sort experimental study on the droplet formation around pins of different geometry for the design of a compact falling droplet absorber
topic Engineering::Mechanical engineering
Droplet
Absorber
url https://hdl.handle.net/10356/139435
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AT romagnolialessandro experimentalstudyonthedropletformationaroundpinsofdifferentgeometryforthedesignofacompactfallingdropletabsorber
AT heyjonathan experimentalstudyonthedropletformationaroundpinsofdifferentgeometryforthedesignofacompactfallingdropletabsorber