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Solar Hydrogen Project

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  1. Solar Hydrogen Project Group Update 21st July 2009

  2. CC-124 growth kinetics model Bojan Tamburic Fit Logistic (Sigmoid) curve of the form: Error caused by O2 bubble evolution Data outliers ‘brushed’

  3. ‘Guess’ initial r and t0 range Minimise the total least squared error of r and t0 Fix r and t0 values Use linear optimisation to recover K

  4. Regression coefficient = 0.98 So K is the maximum attainable OD t0 and r tell us something about the growth rate – but not easy to visualise Biologists typically use doubling time – not really appropriate for logistic curve Gradient at t0 – maximum growth rate

  5. Plan: • Fit logistic curves to existing growth kinetics data • Obtain new data to investigate the effects of light intensity, agitation and CO2 sparging on growth kinetics, but: • Sartorius reactor under modification • Algae appear to be contaminated • Need about 2 months of data collection to obtain ‘good’ results

  6. Solar Hydrogen Project: SD • Fe2O3 work: • First stage of comparative study of different types of Fe2O3: • Old EPFL CVD • Voltammetry • Impedance • Transient photocurrent measurements

  7. Solar Hydrogen Project: SD • Photocurrent transients: • Measured with 0.1M NaOH, solution = water or 80:20 water/MeOH • Set potential to 0.6 V, V = -0.1V • Chopped at ~3 Hz, recorded photocurrent transients at 10-5 s resolution

  8. Fe2O3 (EPFL): NaOH-H2O

  9. Fe2O3 (EPFL): NaOH-H2O/MeOH

  10. Fe2O3 (EPFL): 0.6V

  11. Fe2O3 (EPFL): 0.1V

  12. Fe2O3: EPFL

  13. Conclusions • Preliminary (and not concluded yet) • In the absence of MeOH see cathodic “dark” current, even at 0.6 V. • As applied potential is increased, the photocurrent becomes increasingly transient • As applied potential is increased the cathodic “dark” current increases (relative to the photocurrent)

  14. Photo-electrochemical Reactor Modeling:Week 3 Update Zachary Ulissi

  15. Reactor Design: Original & Wedges

  16. Reactor Design: Extra Post

  17. Reactor Design: Small Wedge

  18. Reactor Design: Extra Post

  19. Mass Transfer In the Laminar Regime(300 ml/min liquid flow) Goal: 2 A/m2

  20. Mass Transfer Limit for Laminar Flow Goal: 2 A/m2

  21. Mass Transfer Limit for Laminar Flow Goal: 2 A/m2

  22. Insufficient Mixing!

  23. Laminar Diffusion Completed