Cargando…

Thermophysical Characterization of Paraffin Wax Based on Mass-Accommodation Methods Applied to a Cylindrical Thermal Energy-Storage Unit

Two mass-accommodation methods are proposed to describe the melting of paraffin wax used as a phase-change material in a centrally heated annular region. The two methods are presented as models where volume changes produced during the phase transition are incorporated through total mass conservation...

Descripción completa

Detalles Bibliográficos
Autores principales: Silva-Nava, Valter, Hernández-Cooper, Ernesto M., Chong-Quero, Jesús Enrique, Otero, José A.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8876929/
https://www.ncbi.nlm.nih.gov/pubmed/35208977
http://dx.doi.org/10.3390/molecules27041189
_version_ 1784658286641938432
author Silva-Nava, Valter
Hernández-Cooper, Ernesto M.
Chong-Quero, Jesús Enrique
Otero, José A.
author_facet Silva-Nava, Valter
Hernández-Cooper, Ernesto M.
Chong-Quero, Jesús Enrique
Otero, José A.
author_sort Silva-Nava, Valter
collection PubMed
description Two mass-accommodation methods are proposed to describe the melting of paraffin wax used as a phase-change material in a centrally heated annular region. The two methods are presented as models where volume changes produced during the phase transition are incorporated through total mass conservation. The mass of the phase-change material is imposed as a constant, which brings an additional equation of motion. Volume changes in a cylindrical unit are pictured in two different ways. On the one hand, volume changes in the radial direction are proposed through an equation of motion where the outer radius of the cylindrical unit is promoted as a dynamical variable of motion. On the other hand, volume changes along the axial symmetry axis of the cylindrical unit are proposed through an equation of motion, where the excess volume of liquid constitutes the dynamical variable. The energy–mass balance at the liquid–solid interface is obtained according to each method of conceiving volume changes. The resulting energy–mass balance at the interface constitutes an equation of motion for the radius of the region delimited by the liquid–solid interface. Subtle differences are found between the equations of motion for the interface. The differences are consistent with mass conservation and local mass balance at the interface. Stationary states for volume changes and the radius of the region delimited by the liquid–solid interface are obtained for each mass-accommodation method. We show that the relationship between these steady states is proportional to the relationship between liquid and solid densities when the system is close to the high melting regime. Experimental tests are performed in a vertical annular region occupied by a paraffin wax. The boundary conditions used in the experimental tests produce a thin liquid layer during a melting process. The experimental results are used to characterize the phase-change material through the proposed models in this work. Finally, the thermodynamic properties of the paraffin wax are estimated by minimizing the quadratic error between the temperature readings within the phase-change material and the temperature field predicted by the proposed model.
format Online
Article
Text
id pubmed-8876929
institution National Center for Biotechnology Information
language English
publishDate 2022
publisher MDPI
record_format MEDLINE/PubMed
spelling pubmed-88769292022-02-26 Thermophysical Characterization of Paraffin Wax Based on Mass-Accommodation Methods Applied to a Cylindrical Thermal Energy-Storage Unit Silva-Nava, Valter Hernández-Cooper, Ernesto M. Chong-Quero, Jesús Enrique Otero, José A. Molecules Article Two mass-accommodation methods are proposed to describe the melting of paraffin wax used as a phase-change material in a centrally heated annular region. The two methods are presented as models where volume changes produced during the phase transition are incorporated through total mass conservation. The mass of the phase-change material is imposed as a constant, which brings an additional equation of motion. Volume changes in a cylindrical unit are pictured in two different ways. On the one hand, volume changes in the radial direction are proposed through an equation of motion where the outer radius of the cylindrical unit is promoted as a dynamical variable of motion. On the other hand, volume changes along the axial symmetry axis of the cylindrical unit are proposed through an equation of motion, where the excess volume of liquid constitutes the dynamical variable. The energy–mass balance at the liquid–solid interface is obtained according to each method of conceiving volume changes. The resulting energy–mass balance at the interface constitutes an equation of motion for the radius of the region delimited by the liquid–solid interface. Subtle differences are found between the equations of motion for the interface. The differences are consistent with mass conservation and local mass balance at the interface. Stationary states for volume changes and the radius of the region delimited by the liquid–solid interface are obtained for each mass-accommodation method. We show that the relationship between these steady states is proportional to the relationship between liquid and solid densities when the system is close to the high melting regime. Experimental tests are performed in a vertical annular region occupied by a paraffin wax. The boundary conditions used in the experimental tests produce a thin liquid layer during a melting process. The experimental results are used to characterize the phase-change material through the proposed models in this work. Finally, the thermodynamic properties of the paraffin wax are estimated by minimizing the quadratic error between the temperature readings within the phase-change material and the temperature field predicted by the proposed model. MDPI 2022-02-10 /pmc/articles/PMC8876929/ /pubmed/35208977 http://dx.doi.org/10.3390/molecules27041189 Text en © 2022 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Silva-Nava, Valter
Hernández-Cooper, Ernesto M.
Chong-Quero, Jesús Enrique
Otero, José A.
Thermophysical Characterization of Paraffin Wax Based on Mass-Accommodation Methods Applied to a Cylindrical Thermal Energy-Storage Unit
title Thermophysical Characterization of Paraffin Wax Based on Mass-Accommodation Methods Applied to a Cylindrical Thermal Energy-Storage Unit
title_full Thermophysical Characterization of Paraffin Wax Based on Mass-Accommodation Methods Applied to a Cylindrical Thermal Energy-Storage Unit
title_fullStr Thermophysical Characterization of Paraffin Wax Based on Mass-Accommodation Methods Applied to a Cylindrical Thermal Energy-Storage Unit
title_full_unstemmed Thermophysical Characterization of Paraffin Wax Based on Mass-Accommodation Methods Applied to a Cylindrical Thermal Energy-Storage Unit
title_short Thermophysical Characterization of Paraffin Wax Based on Mass-Accommodation Methods Applied to a Cylindrical Thermal Energy-Storage Unit
title_sort thermophysical characterization of paraffin wax based on mass-accommodation methods applied to a cylindrical thermal energy-storage unit
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8876929/
https://www.ncbi.nlm.nih.gov/pubmed/35208977
http://dx.doi.org/10.3390/molecules27041189
work_keys_str_mv AT silvanavavalter thermophysicalcharacterizationofparaffinwaxbasedonmassaccommodationmethodsappliedtoacylindricalthermalenergystorageunit
AT hernandezcooperernestom thermophysicalcharacterizationofparaffinwaxbasedonmassaccommodationmethodsappliedtoacylindricalthermalenergystorageunit
AT chongquerojesusenrique thermophysicalcharacterizationofparaffinwaxbasedonmassaccommodationmethodsappliedtoacylindricalthermalenergystorageunit
AT oterojosea thermophysicalcharacterizationofparaffinwaxbasedonmassaccommodationmethodsappliedtoacylindricalthermalenergystorageunit