Your SlideShare is downloading. ×
0
329 Kandavel
329 Kandavel
329 Kandavel
329 Kandavel
329 Kandavel
329 Kandavel
329 Kandavel
329 Kandavel
329 Kandavel
329 Kandavel
329 Kandavel
329 Kandavel
329 Kandavel
329 Kandavel
329 Kandavel
329 Kandavel
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×
Saving this for later? Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.
Text the download link to your phone
Standard text messaging rates apply
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
590
On Slideshare
0
From Embeds
0
Number of Embeds
1
Actions
Shares
0
Downloads
5
Comments
0
Likes
0
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide

Transcript

  • 1. Optimization of AB2 - type alloy composition with superior hydrogen storage properties for stationary applications Kandavel Manickam, David Grant and Gavin Walker Energy and Sustainability Research Division Faculty of Engineering The University of Nottingham ICAER 2013, IIT Bombay
  • 2. Outline 1. Introduction 2. Results of AB2 type alloys • • • • • Materials preparation and characterization P-C-I measurements Thermodynamics Hydrogenation kinetics HP-DSC studies of alloys 3. Summary of results and conclusions
  • 3. Introduction Year Limited reserves CO2 Global warming Alternative clean energies Hydrogen can be a clean energy carrier • High energy density (three time higher than the fossil fuels) • Environmental friendliness (H2O) Hydrogen economy • Production • Storage • Utilization
  • 4. BioCPV • Indo – UK BURD (Bridging the Urban and Rural Divide) Project • Integration of different types of energy sources and energy storage technologies 12 kWh 16 kWh 14 kWh H store End user Electrolyser 7.5 kWh 2520 litres CPV- 15 kWp 120 kWh per day Hydrogen 7 kWh 2350 litres Bio waste 22 kWh 14000 litres Bio gas plant (14 m3) Genset Village electrification 90 kWh
  • 5. Materials selection requirements Hydrogen storage • 7.5 kWh(H2) : 225 g H2 • equivalent to 2520 litres (stp) • Solid State Storage • 15 kg AB alloy (1.6 wt %) • 13 kg of AB2 alloy (1.8 wt %) Commercial Hydralloy C - AB2 alloy • Plateau Pressure : 13 bar • Capacity : 1.3 wt % Aim of the present work Requirements 1 g H2/min Kinetics • AB2 type Laves phase alloys • Composition variation to improve hydrogen storage properties • Effect of non-stoichiometry on the hydrogen storage properties • Identification of suitable composition for the BioCPV application
  • 6. Synthesis & Characterization 172.0 A1+xB2(x = 0, 0.05, 0.075 and 0.1) 40 50 60 70 3 Unitcell volume (Å ) 30 A1+xB2 171.5 x = 0.1 x = 0.075 171.0 170.5 170.0 169.5 Intensity (arb. units) 169.0 0.00 0.04 0.08 0.12 x in A1+xB2 x=0 x = 0.05 x = 0.075 x = 0.1 30 40 (201) 50 2 60 • Single phase formation • Hexagonal structure (C14) • space group P63/mmc (205) (302) (104) (213) x=0 (202) (004) (112) (200) (103) (110) x = 0.05 70 Composition is similar to initial composition (± 1%)
  • 7. Hydrogen storage Pressure – Composition Isotherms Equilibirum Pressure (bar) 100 α phase 2.1 wt % A1.05B2 10 β α+β 1 Plateau pressure o 32 C o 50 C o 60 C o 70 C 0.1 α 0.01 0.0 0.4 0.8 1.2 1.6 Hydrogen concentration (wt %) α+β phase 2.0 β phase
  • 8. Pressure – Composition Isotherms A1.05B2 100 100 Equilibirum Pressure (bar) Hydrogenation Dehydrogenation 15 bar 10 10 1 1 0.01 0.0 1.55 wt % o 32 C o 50 C o 60 C o 70 C 0.1 0.4 0.8 1.2 1.6 1 bar o 32 C o 50 C o 60 C o 70 C 2.0 0.0 0.4 0.8 1.2 1.6 Hydrogen concentration (wt %) Working capacity (1 to 15 bar) at 32 oC ~ 1.55 wt % 2.0 0.1 0.01
  • 9. 100 A1+xB2 Increase in storage capacity • Modification of chemical environment of interstitial sites • Size of the interstitial sites 10 1 o T = 32 C 0.4 0.8 1.2 1.6 Hydrogen Concentration (wt %) 2.0 0.00 2.4 2.0 0.05 0.10 Storage capacity Working capacity Plateau pressure 20 Plateau pressure (bar) x=0 x = 0.05 x = 0.075 x = 0.1 0.1 0.01 0.0 Rietveld analysis and neutron diffraction Hydrogen concentartion (wt %) Equilibrium Pressure (bar) Pressure – Composition Isotherms 16 1.6 12 1.2 8 0.8 4 0.4 0.00 0.05 x in A1+xB2 0.10 0
  • 10. Thermodynamics van’t Hoff relation : 𝑙𝑛𝑃 𝐻2 = Hydrogenation ∆𝐻 ∆𝑆 − 𝑅𝑇 𝑅 Dehydrogenation 2.4 2.4 ln PH2 ln PH2 1.6 1.6 0.8 0.8 0.0028 x = 0.05 x = 0.075 x = 0.1 x = 0.05 x = 0.075 x = 0.1 0.0030 0.0032 Hydrogenation ΔH = - 25 to -28 kJ/mol H2 ΔS = - 92 to -100 J/K/mol H2 0.0028 0.0034 0.0030 0.0032 0.0 0.0034 1/T (1/K) Dehydrogenation ΔH = 28 to 32 kJ/mol H2 ΔS = 94 to 112 J/K/mol H2
  • 11. Hydrogenation Kinetics Avrami-Erofeev rate eq: F = 1- exp(-ktn); n = 0.54 to 3 2.0 6 First order rate equation : - ln(1-F) = kt 5 4 1.5 - ln (1-F) Hydrogen Concentration (wt %) Working Capacity o A1.05B2 1.0 0 0.0 32 C o 50 C o 60 C o 70 C 20 60 40 80 3 2 100 0 A1.05B2 0 20 60 Time (min) 80 100 β phase ln D vs 1/T -29.4 -0.7 -1.4 Ea : 24 ± 1 kJ/mol 0.0030 0.0032 1/T (1/K) 0.0034 2 π 𝐷 𝑟2 r = 5 μm Arrhenius relation D = D0 exp(-Ea/kbT) ln D ln k kd= 0.0028 40 Arrhenius relation k = k0 exp(-Ea/kbT) lnk vs 1/T o 32 C o 50 C o 60 C o 70 C α+β 1 Time (min) α+β phase β -30.0 -30.6 0.0028 Ea : 29 ± 1 kJ/mol 0.0030 0.0032 1/T (1/K) 0.0034
  • 12. Hydrogen gas Heating rate = 5 oC/min Flow rate = 100 ml/min van’t Hoff relation : 𝑙𝑛𝑃 𝐻2 = ∆𝐻 ∆𝑆 − 𝑅𝑇 𝑅 Validation of PCI measurements 0.2 20 bar 16 bar 12 bar 8 bar A1.05B2 0.1 2.8 Dehydrogenation ln PH2 DSC Heat flow (mW/mg) High Pressure DSC 0.0 2.1 Hydrogenation -0.1 1.4 50 100 150 200 250 Hydrogenation Dehydrogenation A1.05B2 0.0026 o 0.0028 0.0030 1/T (1/K) Temperature ( C) A2B2 Interstitial sites: 24l, 12k, 6h1, 6h2 Low temperature peak : 24l and 6h1 High temperature peak : 12k and 6h2 Hydrogenation ΔH = - 29 ± 2 kJ/mol H2 ΔS = - 100 ± 4 J/K/mol H2 Dehydrogenation ΔH = 32 ± 4 kJ/mol H2 ΔS = 117 ± 9 J/K/mol H2
  • 13. Summary of results PCI measurements DSC measurements Plateau slope factor ln(P2/P1) ΔH ΔS ΔH ΔS (kJ/mol H2) (J/K/mol H2) (kJ/mol H2) (J/K/mol H2) Alloy 1 (x = 0) 2.7 - - - 29 ± 2 - 100 ± 5 Alloy 2 (x = 0.05) 2.4 - 26 ± 2 - 98 ± 5 - 29 ± 2 - 100 ± 4 Alloy 3 (x = 0.075) 2.2 - 25 ± 1 - 92 ± 3 -26 ± 3 - 96 ± 8 Alloy 4 (x = 0.1) 1.9 - 28 ± 1 - 100 ± 2 - 28 ± 1 - 99 ± 1 Alloy
  • 14. Summary of results Alloy Plateau pressure (bar) Storage capacity at 15 bar Residual storage capacity (1 bar) Working capacity (15 to 1 bar) Charge time : 95 % (min) 1.7 32 oC 50 oC Max. Storage capacity (wt%) @ ~ 35 bar 1.6 0.3 1.3 6 Alloy 1 (x = 0) 6.0 3.2 Alloy 2 (x = 0.05) 5.3 2.8 8.2 5.6 2.1 1.85 0.3 1.55 5 Alloy 3 (x = 0.075) 3.0 1.7 5.4 3.5 2.1 2.0 0.55 1.45 5 Alloy 4 (x = 0.1) 2.2 1.4 4.1 2.4 2.2 2.1 0.7 1.4 5
  • 15. Conclusions Single phase non-stoichiometric AB2 Laves phase alloys have synthesized successfully Alloy 2 (x = 0.05) is most promising for the BioCPV application Working capacity reached within 5 min at 32 °C 16 % increase in storage capacity than Hydralloy C Interstitial sites can be modified by preparing non stoichiometric alloys
  • 16. Thank you Manickam.Kandavel@nottingham.ac.uk David.Grant@nottingham.ac.uk Gavin.Walker@nottingham.ac.uk Acknowledgement - Research group members

×