Purge duration

Figure 12. Time evolution of cell HFR for four experiments with different purge durations, (reproduced with permission from Tajiri et al.33)...

In order to estimate the fuel utilization, the amount of fuel being sent to the stack must be known. If there is a hydrogen flow meter, the flow rate given by this meter can be used. During purging, the flow rate is likely to be different from that when the fuel cell is in operation at a fixed load. However, since the purging duration is very short (100-500 ms), the flow difference caused... 

Initiators, usually from 0.02 to 2.0 wt % of the monomer of organic peroxides or azo compounds, are dissolved in the reaction solvents and fed separately to the kettie. Since oxygen is often an inhibitor of acryUc polymerizations, its presence is undesirable. When the polymerization is carried out below reflux temperatures, low oxygen levels are obtained by an initial purge with an inert gas such as carbon dioxide or nitrogen. A blanket of the inert gas is then maintained over the polymerization mixture. The duration of the polymerization is usually 24 h (95). 

Processing temperatures should not exceed 180°C, and the duration of time that the material is in the melt state should be kept to a minimum. At the end of a run the processing equipment should be purged with polyethylene. When blow moulding, the blow pin and mould should be at about 60°C to optimise crystallisation rates. Similarly, injection moulds are recommended to be held at 60 5 C. 

In addition to these specialized adsorption designs there are a number of variations on regeneration and cooling processes. The pulse regeneration technique has been practiced for several decades. In this variation we introduce a pulse of hot purge gas over a somewhat limited duration and then follow that with a cooling... 

Duration is the length of time Quick-Purge was used and does not include follow-up monitoring. 

Figure 13.7 Differential pulse voltammetric peaks (argon-purged MeCN/Et4NPF6 0.05 M, room temperature, glassy carbon electrode, scan rate 20 mV/s, pulse height and duration 75 mV and 40 ms) corresponding to the first reduction of the branched compound 56+ and its rotaxanes...

In order to study the annealing behavior of the hydrogen-related defects, infrared absorbance spectra were recorded at 10 K after each step in a series of isochronal heat treatments (annealings) at temperatures in the range 400-1200 °C. The annealings were performed in a furnace purged with argon gas and the duration of each treatment was 30 min. 

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