Hydrogen flow rate

During the test, hydrogen flow rate was raised to a maximum of approximately 55 kg/s (120 Ib/s). About 23 seconds into the experiment, a reduction in flow rate began. Three seconds later, the hydrogen exploded. Electrostatic discharges and mechanical sparks were proposed as probable ignition sources. The explosion was preceded by a fire observed at the nozzle shortly after flow rate reduction began. The fire developed into a fireball of modest luminosity, and an explosion followed immediately. 

Injection port temperature Detector temperature Helium flow rate Hydrogen flow rate ... 

Injector temperature Detector temperature Hydrogen flow rate Airflow rate... 

This can explain why hydrogen flow rate has little effect on liquid phase distribution in the catalyst bed and on conversion. At the same time, higher flow rates of warm hydrogen intensify evaporation of liquid in the inert layer and remove the resulting vapor out of the reactor, leading to the decrease in liquid content in the inert layer. 

Effect of hydrogen flow rate on rate of reaction. Temperature, 25-26 °C pressure, O = 534 mm and = 741 mm of mercury catalyst weight, 0.974 g stirrer speed, 1500 rpm. 

What hydrogen flow rate is required to generate 1.0 ampere of current in a fuel cell (This exercise will generate a very useful conversion factor for subsequent calculations.)... 

Figure 15.7 Variation of the surface morphology of the deposits as a function of the substrate temperature Ts. (a) Ts = 973 to 1073 K, (b) Ts = 873 K, (c) Ts = 823 K, (d) Ts = 773 K. Distance between substrate and vaporization crucible = 2 cm. Hydrogen flow rate = 151/h.

Figure 4. Heating curves for (100) and 3°-misoriented and 6 -misoriented (100) InP surfaces at different hydrogen flow rates and heating rates. The time and temperature required for the nucleation of saturated indium droplets is indicated by arrows. R is the H2Jlow rate (expressed in standard cubic centimeters per minute [seem]), and V is the heating voltage (expressed in volts direct current). (Reproduced with permission from reference 62. Copyright 1983 The Electrochemical Society.)...

In Case B, the hydrogen flow rate is chosen with 2.72-10-6 mobs to approximate a linear change in the molar hydrogen fraction from 0.7 at the entry to 0.299 at the outlet of the anode along the cell area. In this range of the molar fraction, the Nernst voltage changes approximately inversely proportional with the fuel utilisation. 

H2out and H2j being the hydrogen flow rate at the outlet and inlet, respectively, LH Vh2 the lower heating value of hydrogen,. S anode the active surface of the cell, I the electrical current, and F the constant of Faraday. 

Fig. 4.10 (a) H2 concentration at anode/electrolyte interface (b) O2 concentration at cath-ode/electrolyte interface. The operating conditions are oxygen flow rate 12 N1 h 1, hydrogen flow rate 24 N1 h 1, cell voltage 0.8 V at 360 mA cm-1. 

All this uncertainty makes it unlikely that anyone would commit to spending billions of dollars on hydrogen pipelines before there are very high hydrogen flow rates with other means of transport, and before the winners and losers have been determined at both the production end and the vehicle end of the marketplace. In short, for all their virtues, pipelines are not likely to be the main hydrogen transport means over at least the next two decades. 

A sudden reduction of the hydrogen flow rate may thus be a reasonable explanation of the phenomena observed. However, according to the records the total gas flow rate was kept constant. 

Figure 8. Transient behavior upon a sudden reduction of hydrogen flow rate to 1 /4. For model equations and parameters see Table I.

Catalytic tests have been performed in a 500 ml stainless steel batch reactor under hydrogen pressure using 50 g of presulfided catalyst and 125 g of Safanyia atmospheric residue (SAR), The SAR feed had a specific gravity of 0,977 and contained 4.1 wt % S, 0.25 wt % N, 25 wt ppm Ni, 81 wt ppm V and 15.5 wt % C7-asphaltens, A set of used catalysts (symbol P) has been obtained by varying the pressure between 2 to 15 MPa at reaction temperature of 390 °C, contact time of 1 h and hydrogen flow rate of 30 1/h. Further experimental details are reported elsewhere (30). 

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