Numerical prediction of the solidification and melting of encapsulated nano‐enhanced phase change materials

Abstract

The thermal properties of Octadecane vary due to the addition of copper oxide (CuO) nanoparticles. The synthesis of two nano‐enhanced phase change material (NEPCM) required the implementation of the two‐step method, using Octadecane as the base phase change material and CuO nanoparticles at 2.5 and 5.0 wt%. The experimental characterization determined the specific heat capacity, and thermal conductivity of the NEPCMs solid phase, including phase change enthalpy and temperature. These experimental results were then utilized for computational simulation of the thermal charging (solidification) and discharging (melting) processes of NEPCMs within a spherical enclosure, employing the ANSYS/Fluent software. The incorporation of CuO nanoparticles led to an increase in thermal conductivity while causing a decrease in specific heat capacity, enthalpy, and phase change temperature of Octadecane. The computational results revealed a reduction in the melting period and an improvement in the solidification of both NEPCMs. In terms of melting, the convective heat transfer coefficient increased by approximately 27.4% and 3.2% for the NEPCM at 2.5 and 5.0 wt% CuO, respectively. During the solidification process, the overall heat transfer coefficient experienced a significant increase of 43.8% and 59.8% for the NEPCM at 2.5 and 5.0 wt%, respectively.

Full text

RESEARCH ARTICLE
Numerical prediction of the solidification and melting of
encapsulated nano-enhanced phase change materials
Jonathan Cofré-Toledo
1,2
| Francisco Muñoz-Cuevas
1
|
Emilio Jofré-Severino
1
| Luis A. Segura-Ponce
3
| Diego A. Vasco
1
1
Departamento de Ingeniería Mec
anica,
Facultad de Ingeniería, Universidad de
Santiago de Chile, Santiago, Chile
2
Sustainable Energy, Machinery and
Buildings (SEMB) Research Group,
INSPIRES Research Centre, Universitat de
Lleida, Lleida, Spain
3
Departamento de Ingeniería en
Alimentos, Universidad del Bío-Bío,
Chill
an, Chile
Correspondence
Diego A. Vasco, Departamento de
Ingeniería Mec
anica, Facultad de
Ingeniería, Universidad de Santiago de
Chile, Av.Libertador Bernardo O'Higgins
N3363, Estaci
on Central, Santiago, Chile.
Email: diego.vascoc@usach.cl
Funding information
Fondo Nacional de Desarrollo Científico y
Tecnol
ogico
Abstract
The thermal properties of Octadecane vary due to the addition of copper oxide
(CuO) nanoparticles. The synthesis of two nano-enhanced phase change mate-
rial (NEPCM) required the implementation of the two-step method, using
Octadecane as the base phase change material and CuO nanoparticles at 2.5
and 5.0 wt%. The experimental characterization determined the specific heat
capacity, and thermal conductivity of the NEPCMs solid phase, including
phase change enthalpy and temperature. These experimental results were then
utilized for computational simulation of the thermal charging (solidification)
and discharging (melting) processes of NEPCMs within a spherical enclosure,
employing the ANSYS/Fluent software. The incorporation of CuO nanoparti-
cles led to an increase in thermal conductivity while causing a decrease in spe-
cific heat capacity, enthalpy, and phase change temperature of Octadecane.
The computational results revealed a reduction in the melting period and an
improvement in the solidification of both NEPCMs. In terms of melting, the
convective heat transfer coefficient increased by approximately 27.4% and 3.2%
for the NEPCM at 2.5 and 5.0 wt% CuO, respectively. During the solidification
process, the overall heat transfer coefficient experienced a significant increase
of 43.8% and 59.8% for the NEPCM at 2.5 and 5.0 wt%, respectively.
KEYWORDS
computational fluid dynamics, heat transfer coefficient, melting, NEPCM, solidification
1|INTRODUCTION
The energy consumption of buildings in developed coun-
tries accounts for 20%-40% of global consumption,
exceeding other sectors such as industry and transport.
1
Furthermore, in line with the International Energy
Agency (IEA), building activity is responsible for 36% of
global CO
2
emissions.
2,3
In this sector, the heating, venti-
lation, and air conditioning (HVAC) equipment energy
consumption represents 40%-60% of the total.
4,5
For
example, in residential buildings, domestic hot water
production, and heating energy consumption reaches
70% in the IEA member countries, resulting in consider-
able CO
2
emissions.
6
Nowadays, the energy consumption of HVAC systems
has also increased due to the COVID-19 pandemic since, to
avoid COVID-19 infections, it is necessary to increase the
air infiltration rate. This results in longer running time for
air conditioning systems in buildings, with a consequent
increase in energy consumption and CO
2
emissions.
7,8
Application of latent heat thermal energy storage
(LHTES) with O-PCM as a renewable energy source is a
Received: 25 March 2023 Revised: 5 July 2023 Accepted: 4 September 2023
DOI: 10.1002/est2.521
Energy Storage. 2024;6:e521. wileyonlinelibrary.com/journal/est2 © 2023 John Wiley & Sons Ltd. 1of18
https://doi.org/10.1002/est2.521