Performance Analysis of Polymer-Electrolyte Water Electrolysis Cell at a Small-Unit Test Cell and Performance Prediction of Large Stacked Cell

Abstract

Recently the hydrogen energy system has been proposed as a countermeasure for the depletion of fossil fuel and global warming. The polymer electrolyte electrolysis cell ͑PEEC͒ can efficiently produce pure hydrogen under high current density. To design a PEEC properly and to optimize its operating conditions we have measured and analyzed the PEEC performance. Using measured overpotentials we have made a two-dimensional simulation code for PEEC. Calculated results show that the profile of current density and temperature are constant along the water flow direction, because the exothermic heat from overpotentials is almost canceled out by the endothermic heat of both entropy change and evaporation, and by heat transfer to the constant-temperature separators, resulting in a constant water-electrolyzing potential along the flow direction. The current densities measured at a segmented-electrode cell agreed well with the calculated values. By applying this simulation code to a large unit-cell with adiabatic boundary conditions, we have predicted the performance of a large stacked PEEC having an electrode length of 1 m. The predicted cell temperature and current density increase only a little along the flow direction. Under operating conditions with high pressure, the endothermic heat of water evaporation decreases greatly and the cell temperature is apt to increase downstream compared to the atmospheric operation.

Static–dynamic modelling of the electrical behaviour of a commercial advanced alkaline water electrolyser

“…Onda et al [64] developed a 2D mathematical model that was experimentally validated by means of a small PEM cell. Choi et al [65] and Harrison et al [66] proposed two complete models of the permanent electrical behaviour of a PEM electrolysis module giving physical sense to all their terms.…”

Mathematical modeling of high-pressure PEM water electrolysis

“…In the literature, only few papers are dealing with the modeling of PEM water electrolysers, and in most cases, the different aspects (electrode kinetics, mass-transfer in current collectors, mass-transfer and heat-transfer in flow channels) are treated separately. Onda et al [7] provided a model to account for current-voltage relationships. The cell voltage was described by the sum of Nernstian potential, ohmic potential, and also cathodic and anode overvoltages.…”

Mass Transport Limitations in Proton Exchange Membrane Fuel Cells and Electrolyzers

“…Cell efficiency will increase with decreasing resistance. Cell voltages will decrease with increasing cell temperature due to the decrease in overpotential and resistive losses (Onda, Murakami et al 2002). If the individual cell is upgraded to small stacks of approximately fourteen cells, enough heat is generated due to internal resistive losses to make the cell thermally self-sustaining (Badwal, Giddey et al 2006).…”

“…A uniform current density is important to prevent the formation of hotspots, which can further decrease the performance of the electrodes and membranes. If the electrolyzer ratio (flow rate of electrolyzed water divided by the flow rate of the feed water) is less than 10%, the current density distribution in the cell is uniform in the cell (Onda, Murakami et al 2002). At higher ratios, the current density will increase upstream where there is sufficient water and the current density will decrease downstream where there is insufficient water for the reaction.…”