Water Production Rate

In a hydrogen-oxygen fuel cell, 1 mol of water is produced for every two electron charges. Thus, the water production rate is given as 

In Equations 4.84 and 4.85, the number of electron charge transferred for each mole of water produced is = 2 for a hydrogen-oxygen fuel cell. 

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Effect of Temperature on Separation and Pure Water Production Rate(P.W.P.). Fig. 7 shows some results obtained at various temperature with the concentration of NaOCl as 50 mg/l. At lower temperature, sepairation and pure water production rate kept almost constamt value. But with increasing temperature, separation decreases and pure water production rate increases steeply. 

Effect of Concentration on Separation and P.W.P. Fig. 8 shows the effect of concentration on decrease of separation of membranes at 35°C. At lower concentration, separation kept almost constant and pure water production rate decreased. But increasing the concentration 30,UO, and 50 mg/l, separation decreases steeply and pure water production rate contrary increases. At 20 mg/l, deterioration phenomenon is observed after 100 hours as an increase of pure water production rate. In the case of UO and 50 mg/l, steep decrease of separation and increase of pure water production rate are observed. 

Figure 7. E ect of temperature on the change of separation and pure water production rate due to membrane deterioration by sodium hypochlorite [NaOCl] =...

The object of well testing is to determine oil, qas, and water production rates and to establish correlations for production control and allocation. Unfortunately, well flow rates cannot be measured directly because of three phase flow. Consequently, a well rate must be measured by flowing the well individually to a test separator. The well testing process is completely automated and controlled from the HOC, requiring no action on the part of the GC operators during normal operation. Figure 3 shows a test separation train, typical of each of the three... 

From such information, the performance of a proposed solar distiller installation can be anticipated and the area requirements for a specified water production rate determined. 

As implied in Fig. 7, at —3°C the cell can operate indefinitely at steady state. How, then, is the water production rate of 0.0037 mg/cm2/s (40 mA/cm2 current density) balanced by the water removal rate from the cathode CL Assuming the exhaust gases from the cell are fully saturated with water vapor at cell... 

Estimates for the formation rates of Weddell Sea Deep and Bottom Waters, production rate of Antarctic Bottom Water and pathways and time-scales for spreading into the North Atlantic. 

A comparison of the circular polarization with nightly averaged visual magnitudes compiled from [88], which are sensitive to the dust and gas production rates, and the water production rate [89-91] for this observational period shows that the degree of circular polarization in the tail is strongly correlated with cometary activity (Fig. 10). 

Coward, W. A., Prentice, A. M., Murgatroyd, P. R., Davies, H. L., Cole, T. J., Sawyer, M., Goldberg, G. R., Halliday, D., and Macnamara, J. P. (1984). Measurement of COj and water production rates in man using H, -labelled H2O comparison between calorimeter and isotope values. In Human Energy Metabolism Physical Activity and Energy Expenditure Measurements in Epidemiological Researdi Based Upon Direct and Indirect Calorimetry (A. J. H. van Es, ed.), pp. 126-128. EURO-NUT, The Netherlands. 

Figure 3.7. Water production (fuel cell current) and water removal rates as functions of the membrane water activity for an autohumidification PEM fuel cell. The rates are expressed in terms of the current through the external load resistor. A set of curves represents the water production rates for different external load resistances. The water production is based on Eq. (3.1), substituting the membrane resistance as a function of membrane water activity given by Eq. (3.2). Water removal is linearly dependent on the vapor pressure.

Excess water is transported by diffusion through the porous electrode to the cathode plate either in vapor or in liquid phase. The humidity of the incoming oxidant and the electrochemical water production rate need to be in balance to prevent drying out of the electrolyte membrane as well as flooding of the porous electrode stmcture by liquid water. 

In both cases, the reactor which provides thermal or electric energy may be similar to those used for energy production, except that the power must match the water production rate. Some aspects connected with the desalination process which may be relevant to nuclear safety are ... 

Balancing water is the most difficult task for a PEMFC due to the high water production rate and the various water movement possibilities. Although a previous estimate is very helpful in determining the values of certain key parameters, such as the reactant humidification temperature, the stack inlet and outlet temperatures, the coolant flow rate, and the reactant stoichiometric ratio (mainly air), automatic adjustment by the fuel cell system itself is important in achieving the optimal operation conditions, especially if the fuel cell is in the load-following mode. 

Figures 4, 5 and 6 show bed water content, water production rate and bed temperature, respectively.

Figure 5 Multiple-step-ahead predicted values of water production rate in dry basis and experimental values for culture 3.

Effective operation and precise imderstanding of PEM fuel cells can be hindered by the wide scale range of the physical processes, for instance from flow phenomena in millimeter-size stractures to reactant diffusion followed by adsorption on the catalyst clusters. The interrelated character of the various physicochemical processes is another difficulty for the technological/scientific issues for instance, water management depends on temperature and humidity, then on heat and water production rates, thus on current density. .. which can be locally affected by formation of liquid water, i.e. insufficient water management (Fig. 12.1). 

This shows the water vapor flux relative to the water production rate. When the value is greater than unity, all of the produced water can be transported through the MPL in vapor form. 

In case of the Sedimentation Tanks a very long average renewal time (T ) is observed as the water production rate is considerably lower than the design value (two Tanks can provide the max water capacity) and consequently the Operator does not endeavour to optimise the cleaning period. 

CF — total cash flow related to the number of elements necessary for average water production rate,... 

In this chapter, the thermod5mamic principles of fuel cells are presented to estimate the reversible open circuit voltage. Additionally, the procedure for estimating the required reactant gas flow rates, heat generation, and water production rates based on thermodynamic principles is presented. 

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