developments in thermochemical heat storage

Developments in thermochemical heat storage

8th Swiss Symposium Thermal Energy Storage – January 22nd 2021, HSLU Lucerne / held online

Dr. Luca Baldini – Empa, Building Energy Systems and Technologies Group BESTDr. Paul Gantenbein – OST, Institute for Solar Technology SPF

Overview thermochemical reactions/materials

8th Swiss Symposium Thermal Energy Storage - January 22nd 2021, HSLU Lucerne - Dr. Luca Baldini and Dr. Paul Gantenbein 2

Yu, N., R. Wang, and L. Wang, Sorption thermal storage for solar energy.Progress in Energy and Combustion Science, 2013. 39(5): p. 489-514.

Thermochemical energy storage - publications


Sorption storage (TES) - publications


IEA SHC32

IEA SHC42

IEA SHC58

Sorption storage process types


Fumey, B., R. Weber, and L. Baldini, Sorption based long-term thermal energy storage – Process classification and analysis of performance limitations: A review. Renewable and Sustainable Energy Reviews, 2019. 111: p. 57-74.

NaOH considered as sorbento Allowing for high volumetric

energy storageo Low cost / high availability

storage material(50wt%: 180 $/m3, i.e. ~ 0.5-0.8 $/kWh)

LiBr-H2O and LiCl-H2O are potential alternativeso Higher costso Competing with Li batteries

Liquid sorption – Sodium hydroxide (NaOH)


0.00E+00

2.00E+05

4.00E+05

6.00E+05

8.00E+05

1.00E+06

1.20E+06

1.40E+06

20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 100.0

DF (J

/kg)

c(H2O) (wt.%)

Absorption potential DF in function of load c

LiBr-H2O

NaOH-H2O

LiCl-H2O

Dc(NaOH-H2O)

Liquid

Solid(crystallization)

room temperature

Development roadmap


Phys

ical

scal

e

2014-2016 Time2017 2018 2020

COMTES pilot plant

Rededesign of heat and mass exchanger

Heat and mass exchanger upscaling

ehub / NEST demonstratorplant

2019

Lab-scale testing

Spiral finned tube HMX - Lab-scale test rig


Fumey, B., R. Weber, and L. Baldini, Applied Energy, 2017. 200: p. 215-225. doi.org/10.1016/j.apenergy.2017.05.056.

Liquid sorption modelling / building integration


SH Tank

Dry fluid coil

TankssupplydiverterDHWpriority

Brine/WaterHeatPump

High concentration tank Distilled water tank

DHW Tank

SorptionreactorHeating

loopHX

Low concentration tank

Stratos Tzinnis, Master thesis, ETH Zurich / Empa, 2020.

Seasonal load shifting / CO2 emission reduction


Baldini, L. and B. Fumey, Seasonal Energy Flexibility Through Integration of Liquid Sorption Storage in Buildings. Energies, 2020. 13(11): p. 2944.

o Power Unit: Tube Bundle -Heat and Mass Transfer Unit

o Absorber - Desorber (A-D)

Technology Development

8th Swiss Symposium Thermal Energy Storage - January 22nd 2021, HSLU Lucerne - Dr. Luca Baldini and Dr. Paul Gantenbein 11Liquid on Single Tube / Process Development

liquid flow

Heat & Mass Transfer UnitContaining Vacuum Envelope Simple dismountable A-D

(concept: gas / oil burner)

vapour flow

𝒈gravity


Optical visualisation of tube surface wetting - falling film formation

A-D: Optimized six-tube HMX

• Characterisation of the 5 falling film A/D HMX were carried out in both absorption and desorption modus

=> exchanged power, concentration difference as well as heat and mass transfer coefficients and process efficiencyeach HMX are the main output. => Absorption Discharging: temperature lift DT (TA -TE) = 35 K (TE 15 °C) & Dc = 10 wt.%

• Optical characterisation opened the view to some HMX weakness and initiated the start to develop versions with optimised geometries

• Encouraging results obtained with the optimised mesh wrapped tube geometry (up to 25 % more power compared to the reference smooth tube geometry in absorption - discharging - mode)

flow

Power and Concentration Change

Design of a laboratory test rigo Design and construction of a

test rig dedicated to the investigation on heat and mass exchangers as key components of an storage system

o Accurate control and monitoring of the process parameters of the heat and mass exchanger units and the lye feed (subsystem)

Liquid sorption storage – Falling film HMX


Experimental 1 kW absorption-desorption test rig

CAD view of the top part of 1 kW absorption-desorption test rig

Absorber/Desorber (A/D) unit

Balance

Magnetic stirrers

Radar level meters

Sorbent tanks (low and high concentration)

Sorbent pre-heating

Evaporator/Condenser (E/C) unit

Concentration measurement

Stainless steel frame

Hydraulic connections to the

bottom unit

Water tank

E-C

A-D A-D E-C

Tanks

Dosing Pumps

Tanks

Tubes

Major learnings:o Challenging to meet the goals of high concentration difference while achieving

sufficiently large power densitieso There are still mass transfer mechanisms/effects taking place in the HMX which are not

fully understood/exploited yeto There is the potential for low cost equipment and further process optimisation will

further improve this

Further researcho Further experimental assessment and systematic performance improvement of HMX

designo Building integration simulations, hardware-in-the-loop testing, real-scale implementation

and demonstration

Liquid sorption storage


Contact:[email protected]@ost.ch

Supported by:

Thank you for your attention…


mailto:[email protected]

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developments in thermochemical heat storage

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