International Space Station United States Orbital Segment Oxygen Generation System On-orbit Operational Experience

Magnetic phase separation in microgravity

“…"Introduction", electrolyzers stand out as some of the most interesting applications. Electrolyzers are utilized for oxygen production in the Oxygen Generation Assembly on the International Space Station and suffer from the absence of buoyancy as gas bubble removal from the electrode surface is hindered 1,2,7,8 . The first studies of this phenomenon were carried out in the 1960s within the frame of developing a reliable spacecraft environmental control system for oxygen production 83 .…”

“…Numerous phase separation methods have been developed for microgravity conditions. Centrifuges 1,2 , forced vortical flows 3,4 , rocket firing 5,6 , membranes 7,8 , and surface-tensionbased technologies 9,10 , which include wedge geometries [11][12][13][14] , springs 15 , eccentric annuli 16 , microfluidic channels 17 , or porous substrates 18,19 , among others, are the most traditional solutions. As an alternative, the use of electrohydrodynamic forces has been studied since the early 1960s 20 and successfully tested for boiling [21][22][23] , two-phase flow management 24,25 , and conduction pumping 26 applications.…”

Electrolysis in reduced gravitational environments: current research perspectives and future applications

“…The first investigations of water electrolyzers for space applications date back to the 1960s 1,2 , when the main obstacles with developing the technology for space applications were identified: on Earth, the gravitational acceleration gives rise to buoyancy which leads to the detachment of gas bubbles from the electrode surface and a separation of oxygen and hydrogen gas bubbles from the liquid electrolyte. Given the near-absence of buoyant forces in reduced gravitational environments, alternative strategies (e.g., rotating water electrolyzers) have been investigated to artificially introduce gravitation and phase-separation 3,4 , although this is associated with an additional energy cost. Water electrolysis has been investigated intensively in microgravity environments (10 −2 g-10 −6 g) over the past three decades in order to increase the efficiency of devices utilized on spacecrafts and on the International Space Station (ISS) and to understand the governing interfacial processes at the electrode-electrolyte interface [5][6][7][8] .…”