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Development of auxiliary electric power generation system for hydrogen-oxygen spacecraft - redesign of oxygen injector and first stage cylinder head
System that uses calcia-stabilized zirconia-ceramic electrolyte in oxygen concentration cell can directly measure oxygen fugacity in vertical-quench furnace, redox-control system. System can independently vary temperature and oxygen fugacity during experiments, and can record these parameters as function of time.
To provide insulation for tees, elbows, sumps, and valves that are used to pass or store fluids at cryogenic temperatures, individual parts are insulated in an environmentally controlled facility. It is desirable that such insulation be liquid oxygen compatible and be easily removable and reinstallable.
The storage of life support oxygen in the Extravehicular Mobility Unit in the liquid state offers some advantages over the current method of storing the oxygen as a high pressure gas. Storage volume is reduced because of the increased density associated with liquid. The lower storage and operating pressures also reduce the potential for leakage or bursting of the storage tank. The potential for combustion resulting from adiabatic combustion of the gas within lines and components is substantially reduced. Design constraints on components are also relaxed due to the lower system pressures. A design study was performed to determine the requirements for a liquid storage system and prepare a conceptual design. The study involved four tasks. The first was to identify system operating requirements that influence or direct the design of the system. The second was to define candidate storage system concepts that could possibly satisfy the requirements. An evaluation and comparison of the candidate concepts was conducted in the third task. The fourth task was devoted to preparing a conceptual design of the recommended storage system and to evaluate concerns with integration of the concept into the EMU. The results are presented.
NASA is developing a Fine Water Mist Portable Fire Extinguisher for use on the International Space Station. The International Space Station presently uses two different types of fire extinguishers: a water foam extinguisher in the Russian Segment, and a carbon dioxide extinguisher in the US Segment and Columbus and Kibo pressurized elements. Changes in emergency breathing equipment make Fine Water Mist operationally preferable. Supplied oxygen breathing systems allow for safe discharge of a carbon dioxide fire extinguisher, without concerns of the crew inhaling unsafe levels of carbon dioxide. But the Portable Breathing Apparatus offers no more than 15 minutes of capability, and continued use of hose based supplied oxygen systems increases the oxygen content in a fire situation. NASA has developed a filtering respirator cartridge for use in a fire environment. It is qualified to provide up to 90 minutes of capability, and because it is a filtering respirator it does not add oxygen to the environment. The fire response respirator cartridge does not filter carbon dioxide, so a crew member discharging a CO2 fire extinguisher while wearing this filtering respirator would be at risk of inhaling unsafe levels of CO2. Fine Water Mist extinguishes a fire without creating a large volume of air with reduced oxygen and elevated CO2. Compared to the carbon dioxide based Portable Fire Extinguisher, the flight qualification of Fine Water Mist systems requires special care. Qualification of the CO2 based Portable Fire Extinguisher began with the assumption that any fire on ISS would be extinguished if the air in the fire environment reached a critical concentration of CO2. Qualification of a CO2 based system requires the developers to make assertions and assumptions about vehicle geometry and the ability of the extinguisher to deliver CO2 in different geometric configurations, but the developers did not need to make assertions or assumptions about the size of the fire, the temperature, or the heat generation rate. Fine Water Mist systems extinguish a fire predominantly by removing heat -- so qualification standards must evaluate geometry, but also temperature, heat transfer, and heat generation rate. This paper outlines and describes the methods used to develop standards used to qualify Fine Water Mist systems for a human spaceflight environment.
NASA is developing a Fine Water Mist Portable Fire Extinguisher for use on the International Space Station. The International Space Station presently uses two different types of fire extinguishers: a water foam extinguisher in the Russian Segment, and a carbon dioxide extinguisher in the US Segment and Columbus and Kibo pressurized elements. Changes in emergency breathing equipment make Fine Water Mist operationally preferable. Supplied oxygen breathing systems allow for safe discharge of a carbon dioxide fire extinguisher, without concerns of the crew inhaling unsafe levels of carbon dioxide. But the Portable Breathing Apparatus (PBA) offers no more than 15 minutes of capability, and continued use of hose based supplied oxygen system increases the oxygen content in a fire situation. NASA has developed a filtering respirator cartridge for use in a fire environment. It is qualified to provide up to 90 minutes of capability, and because it is a filtering respirator it does not add oxygen to the environment. The fire response respirator cartridge does not filter carbon dioxide (CO2), so a crew member discharging a CO2 fire extinguisher while wearing this filtering respirator would be at risk of inhaling unsafe levels of CO2. Fine Water Mist extinguishes a fire without creating a large volume of air with reduced oxygen and elevated CO2. From a flight hardware design perspective, the fine water mist fire extinguisher has two major elements: (1) the nozzle and crew interface, and (2) the tank. The nozzle and crew interface has been under development for several years. It has gone through several design iterations, and has been part of more than 400 fire challenge and spray characterizations. The crew and vehicle interface aspects of the design will use the heritage of the CO2 based Portable Fire Extinguisher, to minimize the disruption to the crew and integration impacts to the ISS. The microgravity use environment of the system poses a set of unique design requirements specifically for the tank. The nozzle requirements drive a tank pressure that is 2-5 times higher than any commercially available water mist systems. Microgravity requires deliberate separation of gas and water, facilitated by a bladder, a diaphragm, a piston, or separate tanks. This paper will describe the design details of the tank and the nozzle, and discuss the trade studies that informed the decisions to select the tank and nozzle configuration.
NASA is developing a Fine Water Mist (FWM) Portable Fire Extinguisher (PFE) for use on the International Space Station. The International Space Station presently uses two different types of fire extinguishers: a water foam extinguisher in the Russian Segment, and a carbon dioxide extinguisher in the US Segment and Columbus and Kibo pressurized elements. Changes in emergency breathing equipment make Fine Water Mist operationally preferable. Supplied oxygen breathing systems allow for safe discharge of a carbon dioxide fire extinguisher, without concerns of the crew inhaling unsafe levels of carbon dioxide. But the Portable Breathing Apparatus (PBA) offers no more than 15 minutes of capability, and continued use of hose based supplied oxygen system increases the oxygen content in a fire situation. NASA has developed a filtering respirator cartridge for use in a fire environment. It is qualified to provide up to 90 minutes of capability, and because it is a filtering respirator it does not add oxygen to the environment. The fire response respirator cartridge does not filter carbon dioxide (CO2), so a crew member discharging a CO2 fire extinguisher while wearing this filtering respirator would be at risk of inhaling unsafe levels of CO2. FWM extinguishes a fire without creating a large volume of air with reduced oxygen and elevated CO2. The following paper will discuss the unique functional and performance requirements that have been levied on the FWM PFE. In addition, the NASA ISS specific fire standards will be described which were developed to establish acceptable extinguisher performance. The paper will also discuss the flight hardware design. The fin e water mist fire extinguisher has two major elements: (1) the nozzle and crew interface, and (2) the tank. The nozzle and crew interface have been under development for several years. They have gone through several design iterations, and have been part of more than 400 fire challenge and spray characterizations. The crew and vehicle interface aspects of the design will use the heritage of the CO2 based Portable Fire Extinguisher, to minimize the disruption to the crew and integration impacts to the ISS. The microgravity use environment of the system poses a set of unique design requirements specifically for the tank. The nozzle requirements drive a tank pressure that is 2-5 times higher than any commercially available water mist systems. Microgravity requires deliberate separation of gas and water, facilitated by a bladder, a diaphragm, a piston, or separate tanks. This paper will describe status of the project to date, the design details of the tank and the nozzle, and discuss the trade studies that informed the decisions to select the tank and nozzle configuration.
The development of the Three-Man (2.2 lb CO2/man-day) Solid Electrolyte CO2 Electrolysis Breadboard consisted of a Phase 1 and 2 effort. The Phase 1 effort constituted fabrication of three electrolysis cell types and performing parametric testing, off-design testing, and cell life testing. The Phase 2 consisted of the preliminary design, incorporation of palladium (Pd) tubes for hydrogen separation from the electrolyzer cathode feed gases, design support testing, final design, fabrication, and performance testing of the breadboard system. The results of performance tests demonstrated that CO2 electrolysis in an oxygen reclamation system for long duration space-based habitats is feasible. Closure of the oxygen system loop, therefore, can be achieved by CO2 electrolysis. In a two step process the metabolic CO2 and H2O vapor are electrolyzed into O2, H2, and CO. The CO can subsequently be disproportionated into carbon and CO2 in a carbon deposition reactor and the CO2 in turn be recycled and electrolyzed for total O2 recovery. The development effort demonstrated electrolyzer system can be designed and built to operate safely and reliably and the incorporation of Pd tubes for hydrogen diffusion can be integrated safely with predictable performance.
Two alternate oxygen-hydrogen auxiliary propulsion system concepts for use with the space shuttle vehicle were evaluated. The two concepts considered were: (1) gaseous oxygen-hydrogen systems with electric or hydraulic motor driven pumps to provide system pressure and (2) liquid oxygen-hydrogen systems which delivered propellants to the engines in a liquid state without the need for pumps. The various means of implementing each of the concepts are compared on the basis of weight, technology requirements, and operational considerations. It was determined that the liquid oxygen-hydrogen system concepts have the potential to produce substantial weight reductions in the space shuttle orbiter total impulse range.
Hydrogen-oxygen space power supply system
A high pressure oxygen recharge system (HPORS), is being developed for application on board the Space Station. This electrolytic system can provide oxygen at up to 6000 psia without a mechanical compressor. The Hamilton standard HPORS based on a solid polymer electrolyte system is an extension of the much larger and succesful 3000 psia system of the U.S. Navy. Cell modules have been successfully tested under conditions beyond which spacecraft may encounter during launch. The control system with double redundancy and mechanical backups for all electronically controlled components is designed to ensure a safe shutdown.
A literature survey and analysis of the material and process factors affecting the safety of metals in oxygen systems is presented. In addition, the practices of those who specify, build, or use oxygen systems relative to the previous is summarized. Alloys based on iron, copper, nickel, and aluminum were investigated representing the bulk of metals found in oxygen systems. Safety-related characteristics of other miscellaneous metals are summarized. It was found that factors affecting the safety of metals in oxygen systems exit in all phases of the evolutionary process, from smelting and mill techniques through end-production fabrication. The safety of a given metal in an oxygen system was determined to be influenced by the particular service requirement. The metal characteristics should favorably influence fulfillment of these requirements. Thus, no singular metal or alloy could be classified as safest for all types of oxygen service.
A fast-response oxygen monitoring and control system, based on a Y2O3-stabilized ZrO2 sensor, was developed and tested in the laboratory. The system is capable of maintaining oxygen concentration in the CH4-O2-air combustion product gases at 20.9 + or - 1.0 percent. If the oxygen concentration in the exhaust stream differs from that in normal air by 25 percent or more, an alarm signal is provided for automatic tunnel shutdown. The overall prototype system response time was reduced from about 1 sec in the original configuration to about 0.2 sec. The basis of operation and the results of laboratory tests of the system are described.
Water management on ISS is responsible for the provision of water to the crew for drinking water, food preparation, and hygiene, to the Oxygen Generation System (OGS) for oxygen production via electrolysis, to the Waste & Hygiene Compartment (WHC) for flush water, and for experiments on ISS. This paper summarizes water management activities on the ISS US Segment as of March 2022 and provides a status of the performance and issues related to the operation of the Water Processor Assembly (WPA) and Urine Processor Assembly (UPA).
Metal-oxygen and metal-nitrogen systems for use as reduced pressure standards using Sieverts apparatus
Low cost, lightweight ignition system for hydrogen oxygen engine system incorporating multicombustor thrust chambers
The development and performance history of the Apollo extravehicular mobility unit and its major subsystems is described. The three major subsystems, the pressure garment assembly, the portable life-support system, and the oxygen purge system, are defined and described in detail as is the evolutionary process that culminated in each major subsystem component. Descriptions of ground-support equipment and the qualification testing process for component hardware are also presented.
The chemical reactions which occur when potassium sulfide, K2S, and potassium sulfite, K2SO3, are heated at temperatures where their vapor pressures are significant, were studied and the vapor pressures and the partial pressures of the chemical products were measured. Mass spectrometry of the vapor of potassium sulfide revealed only K(g). X-ray studies of the solid residues from vaporization experiments revealed K2S2(s) and chemical analyses of the same solid residues showed that the residues approached a composition K2Sx with x in the range 3-4. Vapor pressure of K2S was measured by simultaneous Knudsen-effusion and torsion-effusion (SKETE) in crucibles of aluminum oxide and of graphite. In each such experiment, the vapor pressures agreed initially, but then the apparent pressure by Knudsen-effusion increased suddenly and remained much greater than that by torsion-effusion for the remainder of the experiment. Results of third-law analysis of the torsion pressures imply a delta H (298K) of formation of K2S(s) of -364 + or - 12 kJ/mol. Vapor pressures over K2SO3(s) were measured by simultaneous Knudsen and torsion-effusion and by mass spectrometry. The vapor pressures of both K2S2O5(s) and K2SO3(s) were nonreproducible at a given temperature due to the vaporization reactions of the materials being irreversible under conditions in effusion cells.