Water management strategy

Detailed validation for low humidity PEFC, where the current distribution is of more interest and likely leads to discovery of optimal water management strategies, was performed most recently. Figure 35 shows a comparison of simulated and measured current density profiles at cell potentials of 0.85, 0.75, and 0.7 V in a 50 cm cell with anode and cathode RH of 75% and 0%. Both experimental data and simulation results display the characteristics of a low humidity cell the local current density increases initially as the dry reactants gain moisture from product water, and then it decreases toward the cathode outlet as oxygen depletion becomes severe. The location of the peak current density is seen to move toward the cathode inlet at the lower cell potential (i.e., 0.7 V) due to higher water production within the cell, as expected. 

Nguyen, T., Knobbe, M. (2003). A liquid water management strategy for PEM fuel cell stacks. /. Power Sources 114,70-79. 

The key parameters to be controlled in this sub-system are air mass flow rate and pressure. Therefore, this section is focused on the characteristics of devices capable to realize useful pressure and flow rate of the oxidant feed (blowers and compressors), postponing the discussion about the integration of air supply system with the other FCS sub-systems to the successive three sections, which are dedicated to thermal and water management strategies and to overall system performance optimization. 

Object of research is the complex surface water system of the cities of Berlin and Potsdam (Fig. 1). To evaluate the ecological effects of the water management strategies on the surface waters, not only the evaluation of each indicator representing a certain scenario characteristic is of interest, but also where these patterns appear. Thus, to detect local effects of the scenarios, the water system has been split into 14 sections, each of which contributes its own characteristics to the decision procedure. 

Table 1. Water management strategies. Abbreviations of wastewater treatment plant names are given in Fig. 1. Example how to read Table 1 Scenario 2 includes the following measures Module (A) reduced amount of water flowing towards Berlin, carrying same nutrient concentration as in the current state. Module (B) technical upgrade of all operating wwtps. Three Wwtps, namely Falkenberg (Fkb), Marienfelde (Mfd) and Oranienburg (Obg) are assumed to be shut down. Module (C) current state of storm water discharge into the surface waters...

The modular structure of the scenarios as described in section Water Management Strategies facilitates to predict the ecological effects of the measures within each module, at least as an ordinal quantity. Therefore, an evaluation solely based on the knowledge of experts, here by members of the project group, becomes possible. To transform the experts expectations into a data matrix, indicators for qualitative evaluation of the measures within each module are defined (see below). For consistent compari-... 

The application of mass-integration tools to the watersheds estabhshes tradeoffs between several objectives such as cost of managing water versus environmental impact [52]. For instance, in the case study given by Lira-Barragan et al. [52] for the Balsas watershed system located in Mexico, a new chemical plant is to be installed. There are 20 candidate sites as shown by Fig. 4.23. Mass integration coupled with MFA can be used to evolve water-management strategies and to aid in the site selection for the chemical... 

To stop the unsustainable exploitation of water resources by developing water management strategies at local, regional, and national levels that promote both equitable access and adequate supplies. 

Flooding Membrane Dehydration Water Management Strategies... 

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