Design and Performance Analysis of Solid Polymer Electrolyte (SPE-type) Water Electrolyzer
Date Issued
2005
Date
2005
Author(s)
Hsu, Ying-Ying
DOI
zh-TW
Abstract
Due to the exhaust of petroleum and the global emission control of green-house gas, “Hydrogen economic” gradually becomes the most potential solution instead of recent carbon-based economic system. With the improvement of renewable energy and fuel cell techniques, the time is ripe for the new market of hydrogen energy. But the key point of this economic system is if the basic facilities for hydrogen evolution are ready or not to support the new market needs. This issue makes the hydrogen evolution technique plays an important role in the future hydrogen economic system.
The main purpose of the SPE-type water electrolyzer is to operate with renewable energy power sources or grid power network, converts electric power into hydrogen gas by electrochemical reaction. The advantages are 1. No corrosive electrolyte is used. 2. Higher hydrogen gas purity without extra purification. 3. Higher energy conversion efficiency and easy to operate under high current density. The design process starts from basic water electrolysis theory and selection of electrode materials, assisted with computational fluid dynamic (CFD) software to find the optimum flow field geometry design. Finally we set up an experimental prototype with self-made MEA and transparent acrylic flow field plates. In order to verify the operating characteristic, conversion efficiency and how gas bubble removal from flow field, the prototype is operated under different operating parameters.
The results reveal that the cell voltage could greatly low down by increasing operating temperature. However, the effect of different recirculation flow rate did not affected much. The most effective method was increasing the anode catalyst amount; this made the maximum energy conversion zone moved to higher current density and increased conversion efficiency. Gas generation rate only affected by input current; in our results, the conversion rate between electrons and hydrogen molecules could reached 90%. Gas purity test reported that the gas purity can up to 97%, which means the sealing is reliable. The flow field observation result revealed no gas was piled up inside flow field; the only thing needs to be noticed is the recirculation flow rate should be set in appropriate value to help removing gas and makes no waste in power required.
Under the situation that cathode catalyst amount 0.4mg/cm2, anode catalyst amount 3.0mg/cm2, operating current density 200mA/cm2, the self-designed electrolyzer single cell can achieve cell voltage 2.8V, gas generation rate 60mL/min, voltage efficiency 53.8%, Faraday efficiency 89.6%, energy conversion efficiency 50.67%.
Subjects
水電解
固態電解質
氫氣生產
water electrolysis
solid polymer electrolyte
hydrogen generation
SDGs
Type
thesis
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