Post on 21-Mar-2017
Construction and Operation of Experimental Simulator with
Thermodynamic Modeling
John Koch (NSF SURF Mentee)Manpreet Bham
Dr. David K. Jeong (NSF SURF Mentor)
Mechanical Engineering, Arkansas State University
John Koch
Content
• Background
• Research Objectives
• Construction and Operation
• Thermodynamic Modeling
• Results and Discussions
• Conclusion
• Future Work
• Acknowledgements
John Koch
Background: CSP
Thermal Energy Storage with
Molten Salts
HotCold
Parabolic Trough
Technology
SOURCE: http://johnbrianshannon.com/spain/Manpreet Bham
Background: CSP• Typical thermal efficiency of renewable power plant is about 10%
• Energy is stored though the phase transition from solid to liquid form of the molten salts
• Energy is released through the phase transition from liquid to solid form during recrystallization of molten salts
• The recrystallization of the molten salts is used to create steam through heat transfer to power a steam turbine
Q=mCpΔTm= mass of molten salt
Cp= Specific Heat of Salt
ΔT= Temperature change
Manpreet Bham
Background: Molten Salts
• Liquid phase of salts that are solids at ambient temperature
• Typical synthetic salt temperature range (NaNO3-KNO3): 220-550°C
• Applications
– Heat transfer fluids for thermal energy storage in Concentrated Solar Power Plants (CSP) or other industrial applications
– Primary and secondary moderators for Nuclear Molten Salt Reactor
• Problem: Keeping the salts in molten phase
Manpreet Bham
Research Objectives
– Use computational methods to find the eutectic temperature and melting point of molten salt alternatives• Using Total Gibbs Energy Minimization
– G = H - TS
– Compare the computational results with experimental data
– Develop more efficient synthesized molten salt for CSP (Mixture of three nitrates: NaNO3,LiNO3,KNO3)
– Validate results with experimental simulator for long term operation
John Koch
Experimental Simulator
• Small scale simulator to test the performance of molten salt developed in our laboratory
• Simulator design mainly focused on molten salt region of Andasol Plant– Using Reynolds's, Thermal
and Geometric analogy of Andasol Plant (6000:1)
• First simulator in the world– 3 other universities have also
targeted construction similar simulators
John Koch
Experimental Simulator• Thermal energy storage simulator
• Equipment:
– 5.5 gallon tank with heating ring
– 0.5 hp Pump Motor
– Closed Pipe loop with heating coil
– K Type Thermocouples
– Watlow EZ-ZONE Controller
– Omega Multi-zone Controller
– 2 types of insulation held by TAPE
• Designed to produce results in time spans of 3, 6 and 9 months
• Maximum operating temperature for components is 500°C
John Koch
Experimental Simulator: Construction
• funded by ASTA and NSF– Design and construction of control panel
– Corrected spacing and orientation of the heating tapes around the pipes• Level the tanks and pipes
– Fabricate bridge for wires to run to the control panel
– Install bridge and connect the heating tapes, heating band, and thermocouples to the control panel
– Added Kaowool insulation around the piping over the heating tapes • After testing heated tapes and pump for appropriate behavior using water at 50°C as the
working fluid
– 20 days of observing the setup up running water at 50°C for leakage test
– Insulate tank with Kaowool insulation
John Koch
Experimental Simulator: Operation
• The system will be turned on
• The computer program will be started and calibrated
• Tank Containing Salts will be heated using Watlowcontroller
• Using Multi-Zone controller heating tapes on pipe will start transferring heat to maintain temperature
• Then pump on tank will be started to circulate the fluid at adjusted speed
• Temperature measurement program will start taking readings periodically
Manpreet Bham
Thermodynamic Modeling with Total Gibbs Energy Minimization
John Koch
Computational
• Program: Matlab R2011a
• NaNO3-KNO3 (Manpreet Bham)
• LiNO3-KNO3 (John Koch)
• Derivation of Gibbs Energy Minimization for a Binary System
• Develop programs for thermodynamic modeling to find melting point of binary salts
John Koch
Thermodynamic Modeling for Binary System (1/3)
EXCESSSTD
i
iitot GGGXG
2
1
ixsiiidi GXRTGG ,, )ln(
TT
T
TTC
T
TTHG mp
mp
p
mp
mp
fiid ln)(
,
2
21,
121,2,
1
21,
221,1,
X
GXGG
X
GXGG
xs
xsxs
xs
xsxs
Manpreet Bham
)ln(2121 cTTbTaXXG
1
21,
221,1,X
GXGG
xs
xsxs
2
21,
121,2,X
GXGG
xs
xsxs
Thermodynamic Modeling for Binary System (2/3)
LiNO3-KNO3 NaNO3-KNO3GIBBS EXCESS TERMS
)( 2112121 XcXbXaXXG
1
21,
221,1,X
GXGG
xs
xsxs
2
21,
121,2,X
GXGG
xs
xsxs
Manpreet Bham
2211 GXGXGtot
))ln(())ln(( 2,22,21,11,1 xsidxsid GXRTGXGXRTGX
)ln()1ln(ln)(
)1(
)ln()1()ln(ln)(
2
1122,
2,
2,
2,
2,
2,1
2
1111,
1,
1,
1,
1,
1,1
cTTbTaXXTRTTT
TTC
T
TTHX
cTTbTaXXTRTTT
TTC
T
TTHX
mp
mp
p
mp
mp
f
mp
mp
p
mp
mp
f
),( 1 TXfGtot
Thermodynamic Modeling for Binary System (3/3)
LiNO3-KNO3
2211 GXGXGtot
))ln(())ln(( 2,22,21,11,1 xsidxsid GXRTGXGXRTGX
)()1ln(ln)(
)1(
)2)(1()ln(ln)(
11122,
2,
2,
2,
2,
2,1
2
111111,
1,
1,
1,
1,
1,1
bXaXXTRTTT
TTC
T
TTHX
bXbXaXXTRTTT
TTC
T
TTHX
mp
mp
p
mp
mp
f
mp
mp
p
mp
mp
f
NaNO3-KNO3
Results: LiNO3-KNO3
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1350
400
450
500
550
600
650
mol KNO3
Te
mp
era
ture
(K
)
Figure 1. KNO3-LiNO3
w/o excess
Kleppa
ASU
• ASU data is from experimental method of DSC• Without excess is only the Standard Gibbs energy ( )
STDG
John Koch
Results: NaNO3-KNO3
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1400
450
500
550
600
650
Mol Fraction
Tem
pera
ture
[K
]
Figure. KNO3-NaNO3
w/o excess
Kleppa
ASU
KNO3Manpreet Bham
Conclusion
• Derived the Total Gibbs Energy Equation for binary system
• Mathematically modeled the Total Gibbs Energy minimization for predicting melting temperature or chemical composition at equilibrium
• Modeling accuracy can be enhanced by applying more accurate curve fitting regression method
• Accomplished construction of experimental simulator scaled down from Andasol CSP in Spain
John Koch
Future Work
• More accurate relationship for excess Gibbs energy in binary system– Experiment to find the coefficients
• Design computational modeling for ternary compounds– Compare with experimental data from the Differential
Scanning Calorimeter (DSC), Thermogravimetric Analyzer (TGA)
• Evaluate performance of salt with experimental simulator for long term application
John Koch
Ackowledgements
• Arkansas Science and Technology Authority (ASTA)
• National Science Foundation (NSF)
• Arkansas State University Office of Research & Technology Transfer (ORTT)
John Koch
THANK YOU!!