Development and experimental characterization of a portable six-cell alkaline electrolyzer using 316L stainless steel electrodes

Abstract

A small alkaline water electrolyzer with a six-cell capacity, using 316L stainless steel as electrodes, has been designed and described to produce distributed hydrogen. Both electrodes has widths of 130 mm, heights of 170 mm, a thickness of 1 mm, and an active surface area of 221 cm². Potassium hydroxide electrolyte at four concentrations (10%, 20%, 30%, and 40% w/w) at atmospheric pressure and temperatures of 25-70°C is used to test the system. Using the ADC-3303D regulated power supply (12.5V/10A, 125W), we obtained a constant average current of 7.75 A at all concentrations. An SD-6000 flowmeter is used to measure hydrogen production with maximum output recorded at 30% KOH concentration and 70°C, 3.8 L/h. The purity of hydrogen is determined by gas chromatography analysis to be more than 99.5% in the absence of moisture. The results of the prolonged testing of greater than 1000 h showed the rate of corrosion of the electrode as low as 0.008 mm/year. It was shown that the system could perform optimally at 30% KOH with a thermoneutral potential efficiency of 72% and a Faraday efficiency of 96%. Its small size (15x20x25 cm) allows industrial applications to be deployed portably. Economic estimates show that the production of hydrogen will cost $28/kg at 2000 h per year
of operation.