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a b c d Figure 4.6. (a)-(d) Temperature Effect on Electrolysis In Figure 4.7, voltage responses of all the cells for varying water flow rates are given at 500mAmp/cm 2 . The figure shows the relation between temperature and voltage. For all water flow rates, as seen in Figure 4.7, temperature has a positive effect on electrolysis efficiency. In this respect, high cell temperature is advantageous for PEM water electrolysis but with respect to thermal stability of cell components used in this thesis, optimum cell temperature was selected as 50 o C. Temperature of the electrolyzers was controlled with an external fan to achieve isothermal operation (as much as possible) at 50 o C especially for high current densities. 50
Voltage 2,25 2,20 2,15 2,10 2,05 2,00 1,95 1 gr/min 3 gr/min 5 gr/min 10 gr/min 1,90 25 30 35 40 45 50 55 Cell Temperature o C Figure 4.7. Voltage of the cells at 500mAmp/cm 2 The temperature increase decreases the cell voltage since both –∆H and –∆G of the reaction change with temperature. The minimum and the thermoneutral electrolysis voltages also depend on temperature. The situation was indicated by LeRoy and coworkers. They calculated the ideal electrolysis voltage using thermodynamic data. Figure 4.8 plotted using data given in that research study summaries the effect of temperature on both thermoneutral and ideal electrolysis voltage (LeRoy et al. 1980). Voltage 1,50 1,45 1,40 1,35 1,30 1,25 1,20 1,15 Ideal Thermoneutral Electrolysis Voltage Ideal Electrolysis Voltage 1,10 0 20 40 60 80 100 120 140 160 Temperature ( o C) Figure 4.8. Minimum and Thermoneutral Electrolysis Voltage 51
Page 1 and 2:
HYDROGEN PRODUCTION FROM WATER USIN
Page 3 and 4:
ACKNOWLEDGEMENTS This study was car
Page 5 and 6:
ÖZET GÜNEŞ PĐLLERĐ ĐLE ÇALI
Page 7 and 8:
4.2. Results on a Single Cell PEM E
Page 9 and 10: Figure 4.16. Hydrogen Production an
Page 11 and 12: CHAPTER 1 INTRODUCTION World energy
Page 13 and 14: Table 1.1. Turkey`s energy usage as
Page 15 and 16: atmosphere according to their hydro
Page 17 and 18: The reaction goes through two half
Page 19 and 20: 2.1. Hydrogen Production Methods CH
Page 21 and 22: 2.2. Electrolyzers Figure 2.1. Vari
Page 23 and 24: electrode design are being sought t
Page 25 and 26: 1 285,830J/mol + H 2O(l) → H 2(g)
Page 27 and 28: another optimization should be done
Page 29 and 30: Figure 2.3. Molecular Formula of Na
Page 31 and 32: hydrophobic substances in electrode
Page 33 and 34: Different than Grigoriev’s work,
Page 35 and 36: voltages. This concept is also vali
Page 37 and 38: Interdigitated flow field is a diff
Page 39 and 40: generator is always working at its
Page 41 and 42: ecord the voltage and the current s
Page 43 and 44: Figure 3.2. Anode side of the elect
Page 45 and 46: 6. Cover the cathode GDL with 1mm t
Page 47 and 48: to deliver water. The front side of
Page 49 and 50: 5. Place the cathode side GDL into
Page 51 and 52: electrolyzer to monitor the potenti
Page 53 and 54: Figure 4.1. “X” type flow field
Page 55 and 56: MEA, there were no electrolysis on
Page 57 and 58: In fact, it was observed on the dis
Page 59: In each run, current density was in
Page 63 and 64: Therefore, for the current cell des
Page 65 and 66: 8Amp, respectively. The calculated
Page 67 and 68: At 500mAmp/cm 2 , the potential dif
Page 69 and 70: The installed system had 6 of this
Page 71 and 72: At 11.00 AM, as the current density
Page 73 and 74: Figure 4.19 shows solar radiance da
Page 75 and 76: On Iztech campus, the system constr
Page 77 and 78: voltage temperature trend observed
Page 79 and 80: REFERENCES Grigoriev S.A.,Porembsky
Page 81 and 82: British Petrol World Statistical Re
Page 83 and 84: Hydrogen Production (ml/min) Hydrog
Page 85 and 86: Hydrogen Production (ml/min) Hydrog
Page 87 and 88: APPENDIX B MASS BALANCE OF A FIVE C
Page 89 and 90: Table B.3. Mass Balance of Species
Page 91 and 92: Stream3; Species stream 3 at 314.6K
Page 93 and 94: Figure B.3. Input and output stream
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