Abstract

Silica Aerogel is material with a special structure consisting of interconnected solid particles of SiO2 forming the skeleton that enclose nanopores filled with confined air and occupying more than 90% of the volume. It is characterized by a thermal conductivity that can reach lower values than any other material. Our aim was to explain the causes of the super-insulation of this material with the use of a calculating method of conductive heat transfer flux in an aerogel structure and determine the equivalent thermal conductivity. For this purpose, numerical specific software was developed to generate random structure of silica aerogel with predefined concentration of solid particles and properties of both skeleton and confined air. Calculation of the conductivity at any point in the confined gas domain shows variable values as a function of the pore size and the location of the point in the pore. A new developed numerical method was used to calculate the equivalent thermal conductivity of the whole structure. Concentration of solid particles has proved not to be the only parameter in which determine the thermal conductivity of silica aerogel and the influence of tortuosity has been demonstrated. A correlation linking thermal conductivity to both concentration of solid particles and tortuosity of the material was suggested.

References

1.
Kistler
,
S. S.
,
1931
, “
Coherent Expanded Aerogels and Jellies
,”
Nature
,
127
(
3211
), pp.
741
741
.10.1038/127741a0
2.
Maleki
,
H.
,
Durães
,
L.
, and
Portugal
,
A.
,
2014
, “
An Overview on Silica Aerogels Synthesis and Different Mechanical Reinforcing Strategies
,”
J. Non-Cryst. Solids
,
385
, pp.
55
74
.10.1016/j.jnoncrysol.2013.10.017
3.
Gurav
,
J. L.
,
Jung
,
I. K.
,
Park
,
H. H.
,
Kang
,
E. S.
, and
Nadargi
,
D. Y.
,
2010
, “
Silica Aerogel: Synthesis and Applications
,”
J. Nanomaterials
,
2010
, pp.
1
11
.10.1155/2010/409310
4.
Takeshita
,
S.
,
Akasaka
,
S.
, and
Yoda
,
S.
,
2019
, “
Structural and Acoustic Properties of Transparent Chitosan Aerogel
,”
Mater. Lett.
,
254
, pp.
258
261
.10.1016/j.matlet.2019.07.064
5.
Alkemper
,
J.
,
Buchholz
,
T.
,
Murakami
,
K.
, and
Ratke
,
L.
,
1995
, “
Solidification of Aluminium Alloys in Aerogel Moulds
,”
J. Non-Crystalline Solids
,
186
, pp.
395
401
.10.1016/0022-3093(95)00060-7
6.
Esquivel-Castro
,
T. A.
,
Ibarra-Alonso
,
M. C.
,
Oliva
,
J.
, and
Martínez-Luévanos
,
A.
,
2019
, “
Porous Aerogel and Core/Shell Nanoparticles for Controlled Drug Delivery: A Review
,”
Mater. Sci. Eng.: C
,
96
, pp.
915
940
.10.1016/j.msec.2018.11.067
7.
Baetens
,
R.
,
Jelle
,
B. P.
, and
Gustavsen
,
A.
,
2011
, “
Aerogel Insulation for Building Applications: A State-of-the-Art Review
,”
Energy Build.
,
43
(
4
), pp.
761
769
.10.1016/j.enbuild.2010.12.012
8.
Shaid
,
A.
,
Fergusson
,
M.
, and
Wang
,
L.
,
2014
, “
Thermophysiological Comfort Analysis of Aerogel Nanoparticle Incorporated Fabric for Fire Fighter's Protective Clothing
,”
Chem. Mater. Eng.
,
2
(
2
), pp.
37
43
.10.13189/cme.2014.020203
9.
Woignier
,
T.
,
Duffours
,
L.
,
Colombel
,
P.
, and
Durin
,
C.
,
2013
, “
Aerogels Materials as Space Debris Collectors
,”
Adv. Mater. Sci. Eng.
,
2013
, pp.
1
6
.10.1155/2013/484153
10.
Buratti
,
C.
,
Moretti
,
E.
,
Belloni
,
E.
, and
Zinzi
,
M.
,
2019
, “
Experimental and Numerical Energy Assessment of a Monolithic Aerogel Glazing Unit for Building Applications
,”
Appl. Sci.
,
9
(
24
), p.
5473
.10.3390/app9245473
11.
Strobach
,
E.
,
Bhatia
,
B.
,
Zhao
,
L.
, and
Wang
,
E. N.
,
2018
, “
Thermal Performance of High-Efficiency Window Technologies
,”
Annu. Rev. Heat Transfer
,
21
, pp.
59
97
.10.1615/AnnualRevHeatTransfer.2019030886
12.
Guo
,
J. F.
, and
Tang
,
G. H.
,
2019
, “
A Theoretical Model for Gas-Contributed Thermal Conductivity in Nanoporous Aerogels
,”
Int. J. Heat Mass Transfer
,
137
, pp.
64
73
.10.1016/j.ijheatmasstransfer.2019.03.106
13.
Dorcheh
,
A. S.
, and
Abbasi
,
M. H.
,
2008
, “
Silica Aerogel; Synthesis, Properties and Characterization
,”
J. Materials Processing Technology
,
199
(
1–3
), pp.
10
26
.10.1016/j.jmatprotec.2007.10.060
14.
Fricke
,
J.
,
Hümmer
,
E.
,
Morper
,
H. J.
, and
Scheuerpflug
,
P.
,
1989
, “
Thermal Properties of Silica Aerogels
,”
Le J. de Phys. Colloques
,
50
(
C4
), pp.
C4
87
.10.1051/jphyscol:1989414
15.
Li
,
Z. Y.
,
Liu
,
H.
,
Zhao
,
X. P.
, and
Tao
,
W. Q.
,
2015
, “
A Multi-Level Fractal Model for the Effective Thermal Conductivity of Silica Aerogel
,”
J. Non-Cryst. Solids
,
430
, pp.
43
51
.10.1016/j.jnoncrysol.2015.09.023
16.
Bi
,
C.
,
Tang
,
G. H.
,
Hu
,
Z. J.
,
Yang
,
H. L.
, and
Li
,
J. N.
,
2014
, “
Coupling Model for Heat Transfer Between Solid and Gas Phases in Aerogel and Experimental Investigation
,”
Int. J. Heat Mass Transfer
,
79
, pp.
126
136
.10.1016/j.ijheatmasstransfer.2014.07.098
17.
Xie
,
T.
,
He
,
Y. L.
, and
Hu
,
Z. J.
,
2013
, “
Theoretical Study on Thermal Conductivities of Silica Aerogel Composite Insulating Material
,”
Int. J. Heat Mass Transfer
,
58
(
1–2
), pp.
540
552
.10.1016/j.ijheatmasstransfer.2012.11.016
18.
Bi
,
C.
,
Tang
,
G. H.
, and
Hu
,
Z. J.
,
2014
, “
Heat Conduction Modeling in 3-D Ordered Structures for Prediction of Aerogel Thermal Conductivity
,”
Int. J. Heat Mass Transfer
,
73
, pp.
103
109
.10.1016/j.ijheatmasstransfer.2014.01.058
19.
Spagnol
,
S.
,
Lartigue
,
B.
,
Trombe
,
A.
, and
Gibiat
,
V.
,
2008
, “
Modeling of Thermal Conduction in Granular Silica Aerogels
,”
J. Sol-Gel Sci. Technol.
,
48
(
1–2
), pp.
40
46
.10.1007/s10971-008-1759-3
20.
Moncho-Jordá
,
A.
,
Odriozola
,
G.
,
Martınez-López
,
F.
,
Schmitt
,
A.
, and
Hidalgo-Álvarez
,
R.
,
2001
, “
The DLCA-RLCA Transition Arising in 2D-Aggregation: Simulations and Mean Field Theory
,”
Eur. Phys. J. E
,
5
(
4
), pp.
471
480
.10.1007/s101890170054
21.
Alrifai
,
B.
, and
Al-Hamadeen
,
H. M.
,
2015
, “
Using Moore Dijkstra Algorithm With Multi-Agent System to Find Shortest Path Over Network
,”
Int. J. Adv. Comput. Sci. Appl.
,
6
(
6
), p.
187
.10.14569/IJACSA.2015.060626
22.
Hoseini
,
A.
,
McCague
,
C.
,
Andisheh-Tadbir
,
M.
, and
Bahrami
,
M.
,
2016
, “
Aerogel Blankets: From Mathematical Modeling to Material Characterization and Experimental Analysis
,”
Int. J. Heat Mass Transfer
,
93
, pp.
1124
1131
.10.1016/j.ijheatmasstransfer.2015.11.030
You do not currently have access to this content.