Browsing by Author "Matsumoto, Yukitaka"

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Bubble Effects on Electrolysis for Water Purification in Microgravity
(51st International Conference on Environmental Systems, 7/10/2022) Matsumoto, Satoshi; Yoshioka, Nasa; Saruwatari, Hideki; Matsumoto, Yukitaka; Ishiwata, Kazuya
The electrolysis under high pressure and high temperature is one of promising water purification processes of urine for future human space exploration missions. Fine gas bubbles are generated around the electrodes by electrolysis. It is considered that the buoyancy acting on the bubbles promotes departure from the electrode and transportation in electrolyte solution. In microgravity where buoyancy disappears, the bubble motion might be different from nominal gravity conditions and affect efficiency of oxidization of organic carbon including urine. In this paper, the behavior of gas bubble is modeled and the effect of gravity on electrolysis process for water purification of urine is estimated. The electrolysis voltage and current experimentally processed in microgravity are compared with the experiment on the terrestrial conditions and the stability and efficiency of electrolysis are discussed.
The Status of JAXA’s Water Recovery System
(48th International Conference on Environmental Systems, 2018-07-08) Nagase, Tomoka; Goto, Masayuki; Ishiwata, Kazuya; Sakai, Yoko; Matsumoto, Yukitaka; Nakanoya, Sogo
Water Recovery System (WRS) is a key-technology for future manned space exploration. JAXA aims at the higher water recovery rate than the current ISS system with no consumable supplies in order to reduce water replenishment. This report summarize features of JAXA’s Water Recovery System, and describes technical challenges encountered. JAXA are planning on-orbit demonstration using a scale model JWRS (JEM Water Recovery System) for technical demonstration for future operational use. It will be launched in JFY2018 and be demonstrated in the Multi-purpose Small Payload Rack (MSPR/MSPR2) in JEM. JWRS is composed by three main units, cation exchange unit, electrolysis unit, and electrodialyzer unit. Main purpose of ISS demonstration is to verify effect of bubble behavior to its water recovery performance in microgravity. The updated system of JWRS is aimed to be used as a part of closed ECLSS for future exploration.
Technology Demonstration of New Water Recovery System onboard ISS
(2024 International Conference on Environmnetal Systems, 2024-07-21) Matsumoto, Satoshi; Akashi, Megumi; Shido, Yohei; Saruwatari, Hideki; Matsumoto, Yukitaka; Izawa, Shuhei; Ishiwata,Kazuya
Life support systems that support human activities even in future far and long-duration human space exploration need to be regenerative in order to minimize the supplies. JAXA is conducting research and development of next-generation water recovery systems to purify the waste water to drinkable water. Our system uses electrolysis under high temperature and high pressure, and electrodialysis to decompose organic carbon and deionize, unlike NASA's distillation and catalytic oxidation methods. The challenges of liquid handling under microgravity are profound, particularly in understanding the unique behavior of bubbles in space compared to the ground. We performed a technical demonstration on the ISS, assuming that water electrolysis exhibits gravity dependence due to bubble formation during the process. In the demonstration experiment, a sub-scale water treatment system was used to purify the artificially synthesis urine as raw water to be treated. At first, it was operated under the same parameters as those that had been previously verified on the ground. Next step, in order to confirm the effect of microgravity, data was obtained by changing the flow rate and electrolytic current. As a result, it was found that water electrolysis could be performed under microgravity conditions with almost the same performance as on the ground, and the flow rate thresholds that indicate microgravity effects were also obtained. In order to better understand the phenomenon, we modeled the bubble behavior and discussed the experimental results in conjunction with the analysis.