Demonstartion eines Absorptionswärmespeichers mit Natronlauge - COMTES Line B

Transcription

1 EU Project COMTES: Combined development of compact thermal energy storage technologies Düsseldorf, march 16 th 2016 Demonstartion eines Absorptionswärmespeichers mit Natronlauge - COMTES Line B Seasonal Solar Thermal Absorption Energy Storage Development Aqueous sodium lye sorbent water sorbate combination P. Gantenbein 1, X. Daguenet-Frick 1, B. Fumey 2, R. Weber 2, K. Goonesekera 3 and T. Williamson 3 1 Institute for Solar Technologies SPF, University of Applied Sciences Rapperswil (CH) 2 EMPA Swiss Federal Laboratories for Materials Science &Technology (CH) 3 Kingspan Renewables Ltd. (Northern Ireland)

2 EU financed project COMTES in the seventh framework programme (FP7 / FP7: COMTES Combined development of compact thermal energy storage technologies COMTES development lines A (adsorption), B (absorption), C (super-cooling of PCM) Research partner: Industry partner: 2

3 Sorption Storage Demonstrator system Type: Liquid Sorption / Absorption Material: Sodium lye (NaOH-H 2 O) / Water Photo of the system container and collector field. EMPA A/D & E/C units EMPA 3D Drawing of the demo-system. A/D & E/C units Photo of the container inside. 3

4 Heat and mass design and construction: Absorption & desorption processes combined heat and mass transfer Components description simulation & design Water (liquid) NaOH - Water NaOH pellets Photo: Liquid Sodium Lye & Solid Sodium Hydroxide Extrinsic parameters - Location (climatic conditions) - Building type - Geometry, Flow rates, etc. Thermo-physical properties of the materials - Concentration c i ; i=1, 2 (1=Water, 2=NaOH) - Temperature T - Pressure p(c, T), boiling and condensing curves - Surface tension s(c, T) - Viscosity h(c, T) etc. 4

5 Liquid sodium lye sorption energy storage concept: Why ABSORPTION? Separation of the units for POWER and CAPACITY process steps in unified chambers CAPACITY Tank size POWER HEX-MEX 5

6 Liquid sodium lye sorption energy storage concept: Seasonal storage with low thermal losses and high volumetric energy density Thermochemical storage based on water absorption/desorption in sodium hydroxide (NaOH) High renewable energy fraction by using solar collectors and environment heat Thermal heat pump principle: - charging: CAPACITY Tank size POWER HEX-MEX 6

7 Liquid sodium lye sorption energy storage concept: Seasonal storage with low thermal losses and high volumetric energy density Thermochemical storage based on water absorption/desorption in sodium hydroxide (NaOH) High renewable energy fraction by using solar collectors and environment heat Thermal heat pump principle: - discharging: CAPACITY Tank size POWER HEX-MEX 7

8 Introduction Heat and mass transfer unit construction: Overview Absorption /Desorption and Evaporation/Condensation units Components description : Wetting measurements Heat storage charging mode Heat storage discharging mode Comparison with the modeling Conclusion and 8

9 verdünnte Lauge diluted lye Tube bundle falling film heat and mass transfer concept: Successful application in absorption chillers (but fixed operation point) High heat transfer rates - mass transfer(?) Process steps combination (seasonal sequential running, costs reduction, compact) Tube bundle technology for the two heat an mass exchangers (A&D and E&C) Simple design & low costs Wasserdampf Recirculation (?) Recirkulation konzentrierte Lauge concentrated lye Schematic of the charging process step 9

10 Modelling of the tube bundle falling film / the heat and mass transfer unit: Model set-up and Desorber modelling Schematic of a single tube bundle row model Daguenet-Frick et al., Solar Energy,

11 Introduction Heat and mass transfer unit construction: Overview Absorption /Desorption and Evaporation/Condensation units Components description : Wetting measurements Heat storage charging mode Heat storage discharging mode Comparison with the modeling Conclusion and 11

12 Overview A/D and E/C unit: Vacuum tight containers (operation under exclusion of non-condensing gasses) Process stages combination (sequential running, costs reduction, compactness) Choice of the tube bundle technology for the two heat an mass exchangers (compactness) A/D unit (chamber 1) vapour feed through E/C unit (chamber 2) NaOH-H 2 O inlet (sorbent) tube bundle flanges heat transfer medium collectors NaOH-H 2 O outlet discharging charging inspection glass water inlets (sorbate) level measurement cell water outlet 12

13 Components description (E/C heat and mass exchanger) Vapour feed through: low pressure losses, radiative disconnection Manifold: designed to ensure an homogeneous fluid distribution Tube bundle unit: - A/D sized without fluid recirculation, E/C with the lower rate possible - most of the connections/sensors placed on the flange Level measurement cell: limitation of the parasitical energy consumption feeding tube manifold plate with nozzles (fluid distribution) tube bundle hair pin (simples handling) vacuum flange E/C unit level measurement cell 13

14 Introduction Heat and mass transfer unit construction: Overview Absorption /Desorption and Evaporation/Condensation units Components description : Wetting measurements Heat storage charging mode Heat storage discharging mode Comparison with the modeling Conclusion and 14

15 Wetting measurements: A/D tube bundle characterization A/D A/D Acquisition of the pictures dark area = presence of droplets Statistics: Achieved on 1000 pictures, at each pixel minimal light intensity value of the field retained Nozzle manifold temperature sensors Post-processing: - Light intensity in function of position - Threshold; wetting fraction ratio calculation Distance 2m Tube bundle (3 x 6) CCD camera Pump Back lamp Light diffusor Front lamp 15

16 A/D tube bundle characterization: Wet surface fraction development in function of the mass flow rate at different positions Modelling with logarithmic trend lines at the top of the tube bundle possible Highest values of the wet surface fraction at the top of tube bundle implementation of temperature sensors => light wet surface fraction enhancement (max 8 % of relative increase at the tube bundle bottom) 16

17 Leakage detection: Helium leakage tests Operation principle: - container under vacuum - outside wall of the container sprayed with He - He ion current intensity variation measurement inside the container in function of time. - Raise of He concentration => leakage detected Leakage issues detected and repaired: - flat gaskets (feed through) - welding seam - dummy flanges Wetting with H 2 O: E & C unit A/D unit set up for mass spectrometry (He leakage test) 17

18 Heat storage discharging mode (absorption process) -1/2- Power in function of temperature difference Exchanged power value far away from numerical predictions Dependence of the exchanger power on the temperature difference between the evaporator and the absorber 18

19 Heat storage discharging mode (absorption process) -2/2- Power in function of flow rate (surface wetting) v e = 0.95 l NaOH-H2O /min; j i = kw; DT = 3-6 K Absorber flow rate: 0.4 l(naoh-h 2 wt=50 %, T=22 C 19

20 Heat storage charging mode (desorption process) -1/3- Power in function of temperature difference Logarithmic dependence of the exchanged power on the temperature difference between the desorber and the condenser. 20

21 Heat storage charging mode (desorption process) -2/3- Tube bundle surface wetting Condenser maximum flow rate: 12 l(h 2 T=20 C Desorber flow rate: 0.4 l(naoh-h 2 wt=30 %, T=50 C No significant influence of the mass flow rate G on the desorption power as the wetting is good already by low mass flow rates. 21

22 Comparison with the modelling (desorption process) -3/3- Desorber modeling in terms of power relatively accurate - especially around the nominal power value Model for the prediction of the heat transfer coefficient outside of the tube has to be improved - Nu=Nu(Re, Pr). 22

23 Introduction Heat and mass transfer unit construction: Overview Absorption /Desorption and Evaporation/Condensation units Components description : Wetting measurements Heat storage charging mode Heat storage discharging mode Comparison with the modeling Conclusion and 23

24 Conclusion: Reaction zone construction philosophy: Easy access to the tube bundles and their accessories ( easy maintenance) Good sight on the process ( fluid distribution / surface wetting & control) Reduced number of gaskets ( low air leakage rate) First measurements / assessments: System is vacuum tight reached E & C unit functioning as expected Manifold concept validated Tube bundles instrumentation do not severely disturb the fluid flow A/D E/C Photo: A/D and E/C units. 24

25 & assessments: Heat and mass exchanger design complies with the desorption process (charging) No heat transfer limitations due to the E & C unit o Absorption process (discharging) has to be improved Outlook further work: Absorption process improvement: - Increasing surface wetting fraction (surfactants, hydrophilic surface) - Increasing surface area (texturing, other geometry) - A/D unified component concept questionable Improvement of the heat and mass transfer model for the desorber tube bundle After 2 s Improved wetting by adding surfactant (NaOH solution + DHSS) 25

26 COMTES: Combined development of compact thermal energy storage technologies Development Line B: Thermal energy storage in a aqueous sodium lye. Thank you for your attention! Financial support by the European Union in the seventh framework programme (FP7 / ) under the grant agreement No is gratefully acknowledged. We gratefully acknowledge financial support of our research institutions EMPA Swiss Federal Laboratories for Materials Science and Technology and HSR University of Applied Sciences of Rapperswil. 26