Z-Latent Heat Storage for Process Heat Applications.pdf
-
Upload
ajit-kamble -
Category
Documents
-
view
226 -
download
0
Transcript of Z-Latent Heat Storage for Process Heat Applications.pdf
-
7/30/2019 Z-Latent Heat Storage for Process Heat Applications.pdf
1/22
Folie 1 >Latent Heat Storage for Process Heat Applications >J ochen Buschle
Latent Heat Storage for Process Heat Applications
J ochen BuschleDLR German Aerospace CenterInstitute of Technical Thermodynamics Stuttgart
Co-Authors: Wolf-Dieter Steinmann, Rainer Tamme
The Tenth International Conference on Thermal Energy Storage,Atlantic City, 31. May 2. June 2006
-
7/30/2019 Z-Latent Heat Storage for Process Heat Applications.pdf
2/22
Folie 2 >Latent Heat Storage for Process Heat Applications >J ochen Buschle
Content
Presentation is presenting first results obtained in the national projectPROSPER dealing with industrial process steam storage.Possible contribution of Germany to planed new Annex 19.
Project partners are XELLA AG and SGL Technologies GmbHDuration 07/2004 06/2007
The project is funded by the Federal Ministry of Economy (BMWi) under
the contract FKZ 032736017
Latent heat steamstorage in process heat applications
Comparsion macro-encapsulation and external arrangement
Simulation results
Concepts to increase the power density of the storage
Conclusion
-
7/30/2019 Z-Latent Heat Storage for Process Heat Applications.pdf
3/22
Folie 3 >Latent Heat Storage for Process Heat Applications >J ochen Buschle
Gas concrete manufacturing process
Hardening of gas concrete (steamatmosphere; max 13 bar)
Batch process, 2 cycles per day
155 kg steamat 13 bar for 1 m gas concrete = 100 kWhth
Xella Porenbeton GmbH (300.000 m/a corresponds to 30 GWhth/a)
weighing and mixing
hardeningcuttingbulking0
4
8
12
pressure[bar]
0 1 2 3 4 5 6 7 8 9 10
time [h]
-
7/30/2019 Z-Latent Heat Storage for Process Heat Applications.pdf
4/22
Folie 4 >Latent Heat Storage for Process Heat Applications >J ochen Buschle
varying-pressure accumulator - Ruths storage
Charging pipe
Discharging pipe
Water feed pipe
Steam
Water
Pressure vessel
-
7/30/2019 Z-Latent Heat Storage for Process Heat Applications.pdf
5/22
Folie 5 >Latent Heat Storage for Process Heat Applications >J ochen Buschle
Process description - State of the art
varying-pressure accumulators
2 Ruths steamaccumulators
70% of the required steamper cycle
is produced in the boiler
live steam;
70%
overflow;10%
Ruths-lowpressure;
15%
Ruths-high pressure; 5%
boiler autoclave 5-8 bar3-5 bar
-
7/30/2019 Z-Latent Heat Storage for Process Heat Applications.pdf
6/22
Folie 6 >Latent Heat Storage for Process Heat Applications >J ochen Buschle
Potential for introducing latent heat steam storage
Isothermal steamaccumulators withPhase Change Material (PCM)
2 PCM enhanced steamaccumulators
(Tm = 152C and 171C)40% of the required steam per cycle isproduced in the boiler
live steam; 40%
overflow; 10%
Latent-high pressure;
25%
Latent-lowpressure; 25%
Latent heatstorage
Latent heatstorage
8 barboiler autoclave 5 bar
-
7/30/2019 Z-Latent Heat Storage for Process Heat Applications.pdf
7/22
Folie 7 >Latent Heat Storage for Process Heat Applications >J ochen Buschle
Macro encapsulation
PCM Gas
Stiff encapsulation required
Definition of minimal gas volume inside capsules
Compensationof volume variation PCM
Avoidance of significantpressure variations
Gas volume requires about 20% of theinternal volume of the capsules
-
7/30/2019 Z-Latent Heat Storage for Process Heat Applications.pdf
8/22
Folie 8 >Latent Heat Storage for Process Heat Applications >J ochen Buschle
External arrangement of PCM
PCM
Additional required:
Headers for the tube register
Unpressurised containment forthe PCM
Pump for circulation required
-
7/30/2019 Z-Latent Heat Storage for Process Heat Applications.pdf
9/22
Folie 9 >Latent Heat Storage for Process Heat Applications >J ochen Buschle
Comparison macro encapsulation and external
arrangement
PCM steam
Boundary conditionstemperature step: 10 Kelvin
pipe diameter: 40 mm
heat transfer coefficient to the steam: neglected
thermal conductivity PCM: 0.5 W/mK
density PCM: 2000 kg/m
same amountof PCM
-
7/30/2019 Z-Latent Heat Storage for Process Heat Applications.pdf
10/22
Folie 10 >Latent Heat Storage for Process Heat Applications >J ochen Buschle
Macro encapsulation vs. external arrangement
40
60
80
100
solidifiedPC
Mm
ass[%]
External arrangement
Macro encapsulation20
0
0 500 1000 1500 2000 2500 3000 3500
time [s]
External arrangementshows higher power level assuming the sameamountof pipe material
-
7/30/2019 Z-Latent Heat Storage for Process Heat Applications.pdf
11/22
Folie 11 >Latent Heat Storage for Process Heat Applications >J ochen Buschle
Macro encapsulation vs. external arrangement
Outside pressure load demands higher wall thickness than inside
pressure load due to buckling
0
0,2
0,4
0,6
0,8
1
1,2
1,4
1,6
2 6 10 14 18 22 26 30
pressure [bar]
wallt
hick
ness[mm]
externally arranged PCM
encapsulated PCM
External arrangement
Macro encapsulation
-
7/30/2019 Z-Latent Heat Storage for Process Heat Applications.pdf
12/22
Folie 12 >Latent Heat Storage for Process Heat Applications >J ochen Buschle
Comparison steam accumulator concepts
varying-pressure
accumulator
Macro-encapsulated
PCM
externally arranged
PCM
pressure vessel:
diameter: 1m; height: 3m; volume: 2.36 m; water level: 80%
PCM enhancement:
diameter tube: 4 cm; mass PCM: 1250 kg; thermal conductivity: 0,5 W/(m K)
-
7/30/2019 Z-Latent Heat Storage for Process Heat Applications.pdf
13/22
Folie 13 >Latent Heat Storage for Process Heat Applications >J ochen Buschle
Simulation modell
ramp
I
Pump 1
true -1000Po...
5050
-
7/30/2019 Z-Latent Heat Storage for Process Heat Applications.pdf
14/22
Folie 14 >Latent Heat Storage for Process Heat Applications >J ochen Buschle
Results simulation
1000 2000 3000 4000 5000
0
20
40
60
80
100
1000 2000 3000 4000 5000
0
1428
42
56
kW
time [s]
time [s]
Power
Provided heat
kWh
-
7/30/2019 Z-Latent Heat Storage for Process Heat Applications.pdf
15/22
Folie 15 >Latent Heat Storage for Process Heat Applications >J ochen Buschle
Required thermal conductivity
0
200
400
600
800
1000
1200
0 5 10 15 20 25 30
k [W/mK]
time[sec.]
h = 100000 W/(mK)
h = 10000 W/(mK)
h = 1000 W/(mK)
thermal conductivity above 5 W / (m K) is advantageous
-
7/30/2019 Z-Latent Heat Storage for Process Heat Applications.pdf
16/22
Folie 16 >Latent Heat Storage for Process Heat Applications >J ochen Buschle
Basic concepts to increase the power density of
thermal energy storage tested at DLR
Increase of the effectivethermal heat conductivity
Increase of the heat transfer area
PCM - Composite Integretion of fins
-
7/30/2019 Z-Latent Heat Storage for Process Heat Applications.pdf
17/22
Folie 17 >Latent Heat Storage for Process Heat Applications >J ochen Buschle
PCM Composite
Solution: Compression of Saltand expanded graphite
Advantages expanded graphite:
Hight thermal conductivity
Corrosion resistance
material canbe machined
-
7/30/2019 Z-Latent Heat Storage for Process Heat Applications.pdf
18/22
Folie 18 >Latent Heat Storage for Process Heat Applications >J ochen Buschle
Integration of Fins
Solution: Foils made of expandedgraphite
Advantages graphite foils:
Hight thermal conductivity(approx. 150 W/mK)
Corrosion resistance
Arrangement of foils verticalto the axis of the heattransfer pipes is optimal
with respectto theanisotropic heatconductivity of expandedgraphite
PCMPCM PCM
PCMPCM PCM
Graphite-foil
PCM
Steam pipe
10 mm
0,5 mm
Graphite-foil
-
7/30/2019 Z-Latent Heat Storage for Process Heat Applications.pdf
19/22
Folie 19 >Latent Heat Storage for Process Heat Applications >J ochen Buschle
Lab scale experiments at DLR
-
7/30/2019 Z-Latent Heat Storage for Process Heat Applications.pdf
20/22
Folie 20 >Latent Heat Storage for Process Heat Applications >J ochen Buschle
Conclusion
Isothermal energy storage is importantespecially for steamprocesses
External arrangementof PCM is advantageousThermal conductivity of 5 W / (m K) is required
Future work:
Lab scale experiment for validationof models
System simulation of gas concret production process with latent heatsteamaccumulator
-
7/30/2019 Z-Latent Heat Storage for Process Heat Applications.pdf
21/22
Folie 21 >Latent Heat Storage for Process Heat Applications >J ochen Buschle
Thank You
for Your Attention
-
7/30/2019 Z-Latent Heat Storage for Process Heat Applications.pdf
22/22
Folie 22 >Latent Heat Storage for Process Heat Applications >J ochen Buschle
Latent heat steam accumulator