A novel exergy-based concept of thermodynamic quality and ...
Thermodynamic strategies for Pumped Thermal Exergy Storage...
Transcript of Thermodynamic strategies for Pumped Thermal Exergy Storage...
Thermodynamic strategies forPumped Thermal Exergy Storage (PTES)
with liquid reservoirs
Pau Farres-Antunez
Dr. Alex White
Department of Engineering
UK Energy Storage ConferenceBirmingham. 1st December 2016
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Thermo-mechanical energy storage (TMES)
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Thermo-mechanical energy storage (TMES)
Compressed air energy storage (CAES)
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Thermo-mechanical energy storage (TMES)
Compressed air energy storage (CAES) Liquid air energy storage (LAES)
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Thermo-mechanical energy storage (TMES)
Pumped thermal exergy storage (PTES)
Compressed air energy storage (CAES) Liquid air energy storage (LAES)
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Thermo-mechanical energy storage (TMES)
Pumped thermal exergy storage (PTES)
Compressed air energy storage (CAES) Liquid air energy storage (LAES)
➔ High efficiency
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Thermo-mechanical energy storage (TMES)
Pumped thermal exergy storage (PTES)
Compressed air energy storage (CAES) Liquid air energy storage (LAES)
➔ High efficiency
➔ High energy density➔ Geographical
independence
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Solid and liquid storage media
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Solid and liquid storage media
PTES with solid reservoirs
➔ Large heat transfer area➔ Pressurised hot tank➔ Thermal fronts
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Solid and liquid storage media
PTES with solid reservoirs PTES with liquid reservoirs
➔ Large heat transfer area➔ Pressurised hot tank➔ Thermal fronts
➔ Limited temperature ranges➔ Unpressurised tanks➔ Tanks at single temperature
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Solid and liquid storage media
PTES with solid reservoirs PTES with liquid reservoirs
➔ Large heat transfer area➔ Pressurised hot tank➔ Thermal fronts
➔ Limited temperature ranges➔ Unpressurised tanks➔ Tanks at single temperature
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Different cycles
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Different cycles
Gas cycle➔ Sensible heat storage➔ High energy density➔ Low work ratio (~2.5)
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Gas cycle
Supercritical CO2
➔ Sensible & latent heat➔ Moderate work ratio (~5)➔ Low energy density
Different cycles
➔ Sensible heat storage➔ High energy density➔ Low work ratio (~2.5)
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Gas cycle
Supercritical CO2
Steam cycle
➔ Sensible & latent heat➔ Moderate work ratio (~5)➔ Lower energy density (x1/4)
➔ Very high work ratio (>100)➔ Latent heat exchangers in
development stage➔ Requires additional Ammonia
cycle for charging phase
Different cycles
➔ Sensible heat storage➔ High energy density➔ Low work ratio (~2.5)
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Thermodynamic strategies
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Thermodynamic strategies
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Thermodynamic strategies
➔ Increasing the top temperature improves WR (→efficiency) and energy density
➔ A limit for Tmax exists due to constraints on compressor and energy storage materials (e.g. common molten salts)
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Thermodynamic strategies
➔ We can continue to improve WR by lowering Tmin
➔ To do so, we require to incorporate a gas-gas regenerator:
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Thermodynamic strategies
➔ We can continue to improve WR by lowering Tmin
➔ To do so, we require to incorporate a gas-gas regenerator:
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Thermodynamic strategies
Same trend applies to power density!
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Thermodynamic strategies
Compressor/expander losses
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Thermodynamic strategies
Compressor/expander losses
Heat exchanger losses
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Thermodynamic strategies
Compressor/expander losses
Two compressions Heat exchanger losses
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Thermodynamic strategies
Compressor/expander losses
Three compressions Heat exchanger losses
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Thermodynamic strategies
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Thermodynamic strategies
➔ Additional stages at cold side allow to use O2 and further increase WR
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Can we build a HEX with +99% efficiency?
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Can we build a HEX with +99% efficiency?
Bejan (1996):
➔ Entropy generation is due to thermal resistance and pressure loss:
➔ For a given mass flux, exists and optimal that minimises
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Can we build a HEX with +99% efficiency?
Bejan (1996):
➔ Entropy generation is due to thermal resistance and pressure loss:
➔ For a given mass flux, exists and optimal that minimises
We can apply the analysis to a counter-flow HEX, flat plate or shell-and-tube:
➔ and
➔ Use standard heat transfer and flow-friction correlations
➔ Find an analytical expression:
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Can we build a HEX with +99% efficiency?
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Can we build a HEX with +99% efficiency?
Turbulent regime
Laminar regime:
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Can we build a HEX with +99% efficiency?
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Can we build a HEX with +99% efficiency?
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Can we build a HEX with +99% efficiency?
~1000m2/MW and ~1m3/MW at 99% efficiency
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Concluding remarks
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Concluding remarks
● PTES: high energy density and geographical independence
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Concluding remarks
● PTES: high energy density and geographical independence
● Using liquid tanks allows to:
Pressurise working fluid
Have lower self-discharge and a well-defined state-of-charge
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Concluding remarks
● PTES: high energy density and geographical independence
● Using liquid tanks allows to:
Pressurise working fluid
Have lower self-discharge and a well-defined state-of-charge
● Several strategies exist to improve Work Ratio
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Concluding remarks
● PTES: high energy density and geographical independence
● Using liquid tanks allows to:
Pressurise working fluid
Have lower self-discharge and a well-defined state-of-charge
● Several strategies exist to improve Work Ratio
● Designing a HEX with ~99% efficiency is key to success
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THANKS FOR LISTENING!
QUESTIONS?
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References:
Acknowledgements and references
Research Funding:● Peterhouse, Cambridge
Funding to attend UKES2016:● Peterhouse, Cambridge● Cambridge University Engineering Department, Ford of Britain Fund
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Extra slides...
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What is Pumped Thermal Exergy Storage?
Literature uses several names…
PTES: Pumped Thermal Energy Storage
PHES: Pumped Heat Electricity Storage
TEES: Thermo-Electrical Energy Storage
Electricity ElectricityThermal exergy Thermal exergy
Heat pump Heat engineStorage
CHEST: Compressed Heat Energy Storage
SEPT: Stockage d'Electricité par Pompage Thermique
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Can we build a HEX with +99% efficiency?
Turbulent regime
Laminar regime:
Min. Dh limited by min. practical LHigher pressures → Higher L and lower Dh