Thesis - Oztek_Muzaffer_T_200508_MA

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The dehydriding procedure was initiated immediately after the system reached ambient temperature at the end of hydriding process. For this procedure, the exit valves were opened to release hydrogen and a minimal argon flow was established using the needle valves. The system was purged with argon for 15 minutes after which the inlet valves were closed followed very quickly by closing the exit valves to maintain atmospheric pressure argon within the system. Dehydriding was accomplished by holding the furnace at the initial temperature for 180 seconds and then heating to T 2 with a ramp rate of 5 °C/min. The furnace was held at T 2 for 180 seconds and then cooled at a rate of 10 °C/min. Dehydriding in a closed system allowed quantization of the H 2 given off by the sample. Hydriding and dehydriding cycles were repeated without removing the sample from the DSC. Because LaNi 5 and LaNi 5 Al x will absorb and release H 2 at ambient temperatures, their dehydriding characteristics were determined using a slightly modified procedure. For these samples, excess H 2 pressure after the hydriding experiment was reduced to 1 atm. Then pressure and thermal data acquisition were started immediately. The system was heated to 150 ºC with no delay period. 2.2.1.2. Thermal Activation Procedure Some samples were not sufficiently activated by ball milling alone. The activation of these samples was accomplished by a thermal cycle in the DSC following milling. This was done by placing the sample in the DSC in a hydrogen atmosphere at 28
approximately 5 atm, and heating the furnace to 150 °C, followed by cooling to ambient temperature. During this activation step, samples were hydrided to some extent, if not completely. Therefore, these samples were heated up to 150 °C under a minimal flow of argon to ensure no hydrogen was left in the sample. 2.2.2. U-Tube Reactor A 1 foot long, 1 inch O.D. seamless stainless steel pipe was bent into a U shape to hold up to 300 grams of sample. The reactor was fitted with 0.5 micron pore size inline filters and needle valves on each end, Figure 7. The compositional analysis of the effluent gas was done by a Buck Scientific type 910 gas chromatograph fitted with a Hayesep DB 100/120, 30 ft, 1/8 inch O.D. stainless steel column obtained from Alltech. The GC utilized a TCD detector and the carrier gas was argon. Samples were taken from a three neck flask connected to the downstream. Sample injection was done with a gas tight 100 µL syringe. The GC was connected to a Dell GX110 PC and the data was recorded using PeakSimple chromatography software. 29
Page 1 and 2: RECOVERY OF HYDROGEN AND HELIUM FRO
Page 3 and 4: ABSTRACT Waste streams of hydrogen
Page 5 and 6: I dedicate this work to my family m
Page 7 and 8: I also would like to cheer for my f
Page 9 and 10: 2.2.2.1. Hydriding and Dehydriding
Page 11 and 12: LIST OF FIGURES Figure 1. Pressure-
Page 13 and 14: Figure 34. Pressure profiles under
Page 15 and 16: 1. INTRODUCTION The focus of this s
Page 17 and 18: ecause of the difference in partial
Page 19 and 20: hydrides by dissolving large amount
Page 21 and 22: hydrogen storage alloy has a specif
Page 23 and 24: • Insensitivity to poisoning by i
Page 25 and 26: hydrogen capacity was not reproduci
Page 27 and 28: showed the lowest plateau pressure
Page 29 and 30: grain boundaries increases the tota
Page 31 and 32: These parameters are generally inte
Page 33 and 34: Figure 4. CaCu5-type P6/mmm structu
Page 35 and 36: In this study, the addition of Al t
Page 37 and 38: 2. EXPERIMENTAL 2.1.Chemicals and R
Page 39 and 40: Figure 5. The high energy Spex 8000
Page 41: 2.2.1.1. Hydriding and Dehydriding
Page 45 and 46: determined by the start and end of
Page 47 and 48: 450 400 coating thickness (Å) 350
Page 49 and 50: 3. RESULTS AND DISCUSSIONS 3.1. Hyd
Page 51 and 52: DSC 111 heat flow/mW Exo 300 Figure
Page 53 and 54: The thermogram associated with the
Page 55 and 56: total time was broken into three 30
Page 57 and 58: The VTiNi sample was subjected to d
Page 59 and 60: solid solution of hydrogen rather t
Page 61 and 62: DSC 111 Heat Flow/mW 180 Exo Figure
Page 63 and 64: 100 rpm setting, the milling vial w
Page 65 and 66: BPR, 400 rpm, 5 minutes) did not re
Page 67 and 68: Table 1: Effects of various milling
Page 69 and 70: Due to the fast kinetics observed a
Page 71 and 72: The mole % Al after milling was les
Page 73 and 74: Figure 24: Percent hydrogen capacit
Page 75 and 76: the start of the heating period, wh
Page 77 and 78: However, it was noted that the part
Page 79 and 80: percent hydrogen was decreased. The
Page 81 and 82: 3.2.2.4. AuPd and Pt Coating on LaN
Page 83 and 84: 1.0 0.8 (a) (b) Wt. % H absorbed 0.
Page 85 and 86: After dehydriding by the sample, th
Page 87 and 88: 19 18 P (atm) 17 16 15 14 0.74 %Al
Page 89 and 90: GC output, arbitrary units 0 5 10 1
Page 91 and 92: sample was LaNi 5 . This may indica
Page 93 and 94:
30 min. 15 min. Intensity (arb. uni
Page 95 and 96:
After milling the percentages of Al
Page 97 and 98:
4. CONCLUSIONS This study has been
Page 99 and 100:
16. Van-Vucht, J.H.N., Kuijpers, F.
Page 101 and 102:
47. Suryanarayana, C., Progress in
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Thesis - Oztek_Muzaffer_T_200508_MA

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