Investigating influence of geometry and operating conditions on local current, concentration, and crossover in alkaline water electrolysis using computational fluid dynamics

Abstract

We use a three-dimensional computational fluid dynamics model to examine the liquid saturation, KOH concentration, and gas crossover in an alkaline diaphragm water electrolysis device. The effects of cell potential, solution feed rate, and aspects of the design such as the locations and widths of channels on performance and crossover were studied. The results build a case for implementing a separator transport model and an electrode/separator interface model because of the concentration changes observed at the anode and cathode. Simulations suggest a strong relationship between solution feed rate and the nature of dissolved gas crossover through the diaphragm due to the differential liquid pressure driving force. This work underscores the importance of three-dimensional modeling for the design of electrochemical cells, as it can identify issues linked to the geometry, e.g., low local current density or high local gas crossover.