1. Performance Analysis of High Temperature Sensible
Heat Storage System during Charging and
Discharging cycles
By
Likhendra Prasad, Hakeem Niyas, P.Muthukumar
Department of Mechanical Engineering
IIT Guwahati
4th International Conference on Advances in Energy Research
IIT Bombay

2. Outline of Presentation
• Introduction
• Objectives of present work
• Thermal modelling
• Results and discussions
• Conclusions
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3. Potential of Renewable Energies
Global Primary Energy Consumption (GPEC)
Solar energy (1800
Wind energy (200
Biomass (20
GPEC)
GPEC)
GPEC)
Geothermal energy (10
GPEC)
Ocean energy (2
GPEC)
Hydro energy (1
GPEC)
Source: Nitsch, 2007
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4. Solar Power
Solar
Energy
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Solar
PV
Solar
Thermal
Solar
Cell
CSP
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Solar
Power
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5. Concentrating Solar Power (CSP)
(a) Parabolic Trough
(b) Linear Fresnel Reflector
(c) Parabolic Dish
(d) Solar Tower
Source: www.csp-world.com
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6. Solar thermal power plant with TES system
HTF
Steam
Superheater
Turbine
Solar
Boiler
TES
Field
Preheater
P
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P
Condenser
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7. Thermal Energy Storage Methods
• Sensible Heat Storage (SHS) Q   s V C p s Tch ( J )
• Concrete, Cast steel, Concrete, etc.
• Latent Heat Storage (LHS)
Tm
T2
Q    s , pc m V C p s , pcm dT  l , pc m  H f g   l , pc m  C pl , pcm
T1
Tm
• Phase change material (PCM)
• Thermochemical Heat Storage (THS) - Reversible chemical reactions
• Metal Hydrides
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(J )

8. Materials for SHS
 Requirements of
SHS Materials
OperatingTemper
Specific heat
Thermal
ature (K)
(kJ/kg K)
conductivity
SHS materials
•
Large operating
temperature
(W/m K)
Reinforced concrete
673
1.00
1.5
2200
Silica fire bricks
973
1.00
1.5
1820
Solid NaCl
773
0.85
7
2160
Cast iron
673
0.56
37
7200
Cast steel
973
0.60
40
7800
•
High heat capacity
•
High thermal
conductivity
•
High Density
•
Stability
•
Low cost and availability
High thermal conductivity materials
Low cost and easily available materials
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9. Objectives of the present work
 To develop a 3-D thermal model for predicting the performances of SHS systems.
 To optimize the number of charging tubes in the storage bed based on charging
time.
 To predict the performance of SHS bed of high conductivity solid material (cast
steel) of capacity 50 MJ.
 To predict the performance of SHS bed of low conductivity solid material
(concrete) of capacity 50 MJ by incorporating the axial fins (copper) on charging
tube surfaces.
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10. Design and Optimization of SHS model
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11. Thermal modelling of SHS model
 Assumptions
• The inlet velocity profile of HTF is fully developed.
• SHSM is isotropic.
• The flow is considered as unsteady, laminar and
incompressible.
• Axial Conduction is negligible
 Governing Equations:

Physical model of SHS bed
Fluid flow: Continuity and N-S Eq.

. v  0


Dv
2
f
  P    v
Dt


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Heat transfer: Convection (solid- liquid interface)
Heat transfer: Conduction (solid)
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Schematic of mathematical model 11

12.  ICs and BCs :
 Performance parameters
•
Charging / discharging time.
•
Energy stored / recovered
•
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Exergy efficiency
Q  s V C p s T ( J )
 Exergy 
Tch  T (t)
Tch  Tatm
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13. Validation of SHS model
Fig.10 (a)
Input parameters for validation [4]
Sl.
Parameters
1
Density of concrete (kg/m3)
2200
2
Specific heat of concrete (J/kg K)
1000
3
Thermal conductivity of concrete (W/m K)
1, 2, 5
4
Diameter of the charging tube (m)
Values
0.02
5
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[31]
623
6
663
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14. Flow and temperature variation of HTF inside the charging tube
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15. Heat Transfer into the cast steel bed during charging
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16. Results and Discussions - Charging
3650 s
683 s
62.39 MJ
Charging time of concrete and cast steel beds
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62.85 MJ
Energy storage rate of concrete and cast steel
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beds
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17. Results and Discussions - Charging
4493 s
3650 s
3379 s
Effect of HTF velocity on charging time of
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concrete bed
1400 s
683 s
430 s
Effect of HTF velocity on charging time of cast
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steel bed
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18. Results and Discussions - Charging
Axial Temperature variation of HTF during
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charging of concrete bed
Axial Temperature variation of HTF during
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charging of cast steel bed
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19. Results and Discussions - Discharging
7200 s
1820 s
59.78 MJ
Discharging time of concrete and cast steel beds
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62.75 MJ
Energy discharge rate of concrete and cast steel
beds
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20. Results and Discussions - Discharging
Effect of HTF velocity on discharging time of
Effect of HTF velocity on discharging time of
concrete bed
cast steel bed
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21. Results and Discussions - Discharging
Axial Temperature variation of HTF during
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discharging of concrete bed
Axial Temperature variation of HTF during
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discharging of cast steel bed
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22. Results and Discussions
Exergy efficiency variation
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23. Conclusions
•
Thermal models for predicting the charging and discharging characteristics of SHS systems have been developed.
•
The number of charging tubes has been optimized based on the charging time of the SHS bed.
•
Heat transfer enhancement technique is implemented by adding fins on the outer surface of charging tubes.
•
The charging time and energy stored in the SHS bed are found to be 3650 s and 683 s, 62.39 MJ and 62.85 MJ for concrete
and cast steel respectively.
•
The predicted discharging time of SHS beds are 7200 s for concrete bed and 1850 s for the cast steel bed.
•
The energy discharged from the beds in their respective discharging times are found to be 59.78 MJ for concrete bed and
62.75 MJ for cast steel bed.
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24. References
[1]
Gil A., Medrano M., Martorell I. and Cabeza F. (2010) State of the art on high temperature thermal energy
storage for power generation. Part 1-Concepts, materials and modellization, Renewable and Sustainable Energy
Reviews, 14, pp. 31-55.
[2]
Khare S., Knight C., and McGarry S. (2013) Selection of materials for high temperature sensible energy
storage, Solar Energy Materials and Solar Cells, 115, pp. 114-122.
[3]
Sragovich, D. (1989) Transient analysis for designing and predicting operational performance of a high
temperature thermal energy storage system, Solar Energy, 43, pp. 7-16.
[4]
Tamme, R., Laing, D. and Steinmann, W. (2004) Advanced thermal energy storage technology for parabolic
trough, Journal of Solar Energy Engineering, 126, pp. 794-800.
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25. References
[5]
Laing, D., Steinmann, W., Tamme, R. and Richter, C. (2006) Solid media thermal storage for parabolic trough
power plants, Solar Energy, 86, pp. 1283-1289.
[6]
Nandi, B.R., Bandyopadhyay, S. and Banerjee, R. (2012) Analysis of high temperature thermal energy storage for solar
power plant, Proceedings of the 3rd IEEE International Conference on Sustainable Energy Technology, pp. 438-444.
[7]
John, E.E., Hale, W. M. and Selvam, R. P. (2011) Development of a high-performance concrete to store thermal
energy for concentrating solar power plants, Proceedings of the 5th ASME International Conference on Energy
Sustainability, pp. 523-529.
[8]
Tian, Y. and Zhao, C.Y. (2013) A review of solar collectors and thermal energy storage in solar thermal
applications, Applied Energy, 104, pp. 538-553.
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26. THANK YOU
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