A new concept for long-term solar thermal storage is based on the absorption properties of aqueous calcium chloride. Water, diluted and concentrated calcium chloride solutions are stored in a single tank. An immersed heat exchanger and stratification manifold are used to preserve long-term sorption storage, and to achieve thermal stratification. The feasibility of sensible heating the tank via large-scale natural convection without mixing salt solutions is demonstrated via measurements of velocity, CaCl2 mass fraction, and temperature in a 1500 l prototype tank. Experiments are conducted over a practical range of the relevant dimensionless parameters. For Rayleigh numbers from 3.4 × 108 to 5.6 × 1010 and buoyancy ratios from 0.8 to 46.2, measured Sherwood numbers are 11 ± 2 to 62 ± 9, and the tank is thermally stratified. Convective mixing between salt layers is inhibited by the presence of a steep density gradient at the interface between regions of differing mass fraction. The predicted storage time scales based on mixing via natural convection for the reported Sherwood numbers are 160–902 days.

References

References
1.
Hadorn
,
J. C.
,
2008
, “
Thermal Energy Storage: Overview of Technologies and Status for Solar Heat
,”
Proceedings Eurosun 2008
,
Lisbon, Portugal
,
October 7–10
.
2.
Bales
,
C.
,
Gantenbein
,
P.
,
Jaehnig
,
D.
,
Kerskes
,
H.
,
van Essen
,
M.
,
Weber
,
R.
, and
Zondag
,
H.
,
2008
, “
Chemical and Sorption Storage—Results From IEA-SHC Task 32
,”
Proceedings of Eurosun 2008
,
Lisbon, Portugal
,
October 7–10
.
3.
Hauer
,
A.
,
2008
, “
Sorption Storages for Solar Thermal Energy—Possibilities and Limits
,”
Proceedings of Eurosun 2008
,
Lisbon, Portugal
,
October 7–10
.
4.
Quinnell
,
J. A.
,
Davidson
,
J. H.
, and
Burch
,
J.
,
2011
, “
Liquid Calcium Chloride Solar Storage: Concept and Analysis
,”
ASME J. Sol. Energy Eng.
,
133
, p.
011010
.10.1115/1.4003292
5.
Kessling
,
W.
,
Laevemann
,
E.
, and
Kapfhammer
,
C.
,
1998
, “
Energy Storage for Desiccant Cooling Systems Component Development
,”
Sol. Energy
,
64
, pp.
209
221
.10.1016/S0038-092X(98)00081-4
6.
Bales
,
C.
,
2006
, “
Thermal Storage With the Thermo-Chemical Accumulator
,”
Proceedings of Ecostock
,
Galloway, New Jersey
,
May 30–June 2
.
7.
Weber
,
R.
, and
Dorer
,
V.
,
2008
, “
Long-Term Heat Storage With NaOH
,”
Vacuum
,
82
, pp.
708
716
.10.1016/j.vacuum.2007.10.018
8.
Quinnell
,
J. A.
, and
Davidson
,
J. H.
,
2012
, “
Distributed Solar Thermal: Innovations in Thermal Storage
,”
Annu. Rev. Heat Transfer
,
15
, pp
7
35
.10.1615/AnnualRevHeatTransfer.2012004617
9.
Woods
,
J.
,
Pellegrino
,
J.
,
Kozubal
,
E.
,
Slayzak
,
S.
, and
Burch
,
J.
,
2009
, “
Modeling of a Membrane-Based Absorption Heat Pump
,”
J. Membr. Sci.
,
337
(
1–2
), pp.
113
124
.10.1016/j.memsci.2009.03.039
10.
Thorpe
,
S. A.
,
Hutt
,
P. K.
, and
Soulsby
,
R.
,
1969
, “
The Effect of Horizontal Gradients on Thermohaline Convection
,”
J. Fluid Mech.
,
38
(
2
),
pp 365
400
.10.1017/S0022112069000231
11.
Popiel
,
C. O.
,
Wojtkowiak
,
K.
,
Bober
,
K.
,
2007
, “
Laminar Free Convective Heat Transfer From an Isothermal Vertical Slender Cylinder
,”
Exp. Therm. Fluid Sci.
,
32
, pp.
607
613
.10.1016/j.expthermflusci.2007.07.003
12.
Holman
,
J. P.
,
2002
,
Heat Transfer
,
9th ed.
,
McGraw-Hill
,
New York
.
13.
Wirtz
,
R. A.
, and
Reddy
,
C. S.
, “
Heat and Mass Transport Across Diffusive Interfaces Bounded by Turbulent Convecting Regions
,”
Int. J. Heat Mass Transfer
,
19
, pp.
471
478
.10.1016/0017-9310(76)90159-9
14.
2009
,
TSI Insight 3G Data Acquisition, Analysis, and Display Software Platform User's Guide
,
Shoreview, MN
.
15.
Bergman
,
T. L.
, and
Ungan
,
A.
,
1988
, “
A Note on Lateral Heating in a Double-Diffusive System
,”
J. Fluid Mech.
,
194
, pp.
175
186
.10.1017/S0022112088002940
16.
Nishimura
,
T.
,
Sakura
,
S.
, and
Ogata
,
Y.
,
2000
, “
Mass Transfer Through the Diffusive Interface in a Two-Layer Salt-Stratified System Under a Horizontal Temperature Gradient
,”
Chem. Eng. Sci.
,
55
, pp.
5301
5309
.10.1016/S0009-2509(00)00154-8
17.
Liu
,
W.
,
Davidson
,
J. H.
, and
Kulacki
F. A.
,
2004
, “
Natural Convection From a Tube Bundle in a Thin Inclined Enclosure
,”
ASME J. Sol. Energy. Eng.
,
126
(
2
), pp.
67
75
.10.1115/1.1677432
18.
Conde
,
M. R.
,
2004
, “
Properties of Aqueous Solutions of Lithium and Calcium Chlorides: Formulations for Use in Air Conditioning Equipment Design
,”
Int. J. Therm. Sci.
,
43
, pp.
367
382
.10.1016/j.ijthermalsci.2003.09.003
19.
Woods
,
J.
,
Burch
,
J.
, and
Kozubal
,
E.
,
2011
, “
High-Solar-Fraction Heating and Cooling Systems Based on Liquid Desiccants
,”
Proceedings of the American Solar Energy Society
,
Rayleigh, NC
,
May 17–20
.
You do not currently have access to this content.