Oxygen stoichiometric ratio

The disagreement in magnesium to oxygen stoichiometric ratio in the final product is very likely due to the slow reaction of MgO rod surface under ambient conditions with CO2 and H2O yielding magnesium hydroxide and magnesium carbonate ... 

Current-voltage curves at 200 °C (filled square), 210 °C on the 5th (filled circle) and 15th (open circle) day of operation and 220 °C (filled diamond) and (c) cell potential versus time at 0.2 A cm and at several operating temperatures between 200 and 220 °C. For (b) and (c), the MEA was based on the cross-linked Copolymer XIIcl-btt(IOO) (.X = 70, z = 10). Active area 4 cm. Dry gases with hydrogen and oxygen (stoichiometric ratio of 1.2 and 2, respectively) at ambient pressure. Reproduced from [27] with permission of the Royal Society of Chemistry... 

An H2/Air fuel cell operates with hydrogen utilization of 84% and oxygen stoichiometric ratio of 2. Both hydrogen and air must be fully saturated at the cell operating pressure and temperature. Which of the following is tme ... 

Air is fully saturated with water vapor at fuel cell inlet and at fuel cell outlet (actually there is also liquid water dripping at the outlet). The air temperature is the same at the inlet and at the outlet. The fuel cell operates with oxygen stoichiometric ratio of 2. Air passes through a singlechannel serpentine flow field. 

In the case of an air-breathing fuel cell, higher oxygen stoichiometric ratio ... 

A fuel cell has 100-cm active area covered by six parallel channels on the cathode. Each channel is 0.8 mm wide and 0.8 mm deep, with equal spacing between the channels of 0.8 mm. The fuel cell generates 0.8 A/cm. Air at the inlet is fully saturated at 60°C. Pressure at the inlet is 200 kPa, and there is a 15-kPa pressure drop through the flow field. Oxygen stoichiometric ratio is 2.5. Calculate the velocity and Reynolds number at the air inlet and outlet (neglect liquid water at the outlet). 

Consider a fuel cell stack that can operate at either 300 kPa or 170kPa (inlet pressure) with oxygen stoichiometric ratio of 2. The stack performance (polarization curve) is shown in Figure 5.1. Calculate the net power output and the net efficiency at both pressures. Assume current density of 800mA/cm. ... 

FIGURE 9-31. Efficiency of a PROX reactor as a function of oxygen stoichiometric ratio and CO content at the inlet. 

From Eq. (4-la) the stoichiometric concentration of methane in oxygen is 1 part in 3 = 33.3 mole percent methane. From Eq. (4-lb) the approximate stoichiometric concentration of methane in air is 1 part in 3 -E (158/21) = 9.5 mole percent methane. Tims, a mixtnre of 15 mole percent methane in oxygen has a stoichiometric ratio (p = 15/33.3 = 0.45 (lean), while the same methane concentration in air has a stoichiometric ratio (p = 15/9.5 = 1.58 (rich). 

For paraffins the stoichiometric ratio decreases as the nnmber of carbon atoms increases. Using a more precise calcnlation (which inclndes other species snch as CO, OH, etc.) than that shown in Eq. (4-lb), methane s stoichiometric ratio in air is 9.48 mole percent, propane s is 4.01 mole percent, and hexane s is 2.16 mole percent. Hydrogen, which combines with oxygen to form only water, has a stoichiometric ratio of 29.6 mole percent in air. 

Stoichiometric ratio The precise ratio of air (or oxygen) and flammable material which would allow all oxygen present to combine with all flammable material present to produce fully oxidized products. 

Such tight mixture control is beyond the capability of the traditional carburetor. Consequently, after sorting through a number of alternatives, industry has settled on closed-loop-controlled port-fuel injection. Typically, an electronically controlled fuel injector is mounted in the intake port to each cylinder. A sensor in the air intake system tells an onboard computer what the airdow rate is, and the computer tells the fuel injectors how much fuel to inject for a stoichiometric ratio. An oxygen sensor checks the oxygen content in the exliaust stream and tells the computer to make a correction if the air/fuel ratio has drifted outside the desired range. This closed-loop control avoids unnecessary use ot an inefficient rich mixture during vehicle cruise. 

Oxygen inhibition of NO reduction may operate by its greater affinity for hydrogen and CO. Several authors have found that when the molar ratio of 02/C0 is between the stoichiometric ratio of 0.5 and 0.7, the rate of reduction of NO rapidly falls to zero. They concluded that NO reduction can proceed only with an excess of hydrogen and CO 38, 39, 102). Jones et al. have found that below the temperature of 400°F, hydrogen prefers to attack NO instead of oxygen over platinum and palladium. This preference does not extend above 400°F 103). 

Hydrocarbon-rich conditions imply that oxygen is the limiting reactant, due to the high oxygen-to-hydrocarbon stoichiometric ratio in n-hexane ammoxidation. Therefore, the conversion of the hydrocarbon is low this should favour, in principle, the selectivity to products of partial (amm)oxidation instead of that to combustion products. 

The maximum rate of fuel that can bum in the control volume dz in Figure 10.5(a) is that which reacts completely with the entrained oxygen or with a known stoichiometric ratio of oxygen to fuel, r. Thus, we can write... 

In addition to the hydrogen partial pressure in the feed, the 02/C0 stoichiometric ratio also influences the selectivity of the catalyst. If excess oxygen is present in the reactor feed (1 = 2.5), more oxygen is available for the hydrogen oxidation reaction to form water as compared to the case when these two reactants are present in the stoichiometric ratio equal to 1 (/. = 1), which is clear if we compare full and open circles as well as full and open squares in Figure 7.11a. 

Suppose you also wanted to know how many grams of oxygen it would take to react with the 19.9 mol of iron. All you would need to do would be to change the stoichiometric ratio and the molar mass ... 

Equation (59) states that the amount of CO diffusing out is proportional to the oxygen diffusing in. The proportional function is determined by the intrinsic kinetics and is the stoichiometric ratio of CO to oxygen. The splutions to Eqs. (55) and (56) are ... 

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