Environmental Control And Life Support Research Articles

Exergy Analysis of Electrochemical Systems for Space Exploration

Human exploration of space, facilitated by electrochemical systems, will require integration of many seemingly disparate systems including but not limited to power systems, in situ resource utilization (ISRU), and environmental control and life support (ECLS). Through combining expressions of the First and Second Laws of Thermodynamics exergy quantifies the useful work that can be obtained from a system, subject to environmental limitations. This approach provides a means of integrating diverse systems and components based on one consistent and physically meaningful property: exergy. Using this property as a basis, diverse systems can be analyzed and integrated effectively based on the exergy destruction and exergy efficiency. Here, the applicability of exergy analysis to systems design and integration is demonstrated through two examples involving electrochemical systems that support human space exploration.First, analysis of the ECLS system aboard the International Space Station (ISS) is conducted to assess its overall performance in terms of exergy destruction rates and exergy efficiency. The ECLS system is divided into constituent subsystems which are further divided into key components. Based on this system decomposition, exergy balances are derived for each component and subsystem. Special focus is given to the Oxygen Generation Assembly (OGA) within the ECLS Atmospheric Revitalization Subsystem. The results of parametric studies of the OGA proton exchange membrane electrolyzer performance are presented with an emphasis on the impacts of operational conditions on exergy efficiency. This electrolyzer is a significant contributor to system exergy destruction and exhibits a low exergetic efficiency. It therefore presents an opportunity for improving overall ECLS system performance.Following the example of ECLS exergy analysis, the application of exergy analysis to the integration of power and ISRU systems for lunar exploration is presented through system level models. Exergy destruction and efficiency are quantified over the lunar diurnal cycle for power and ISRU systems. The power systems analysis focuses on photovoltaic arrays paired with battery and regenerative fuel cell systems. The ISRU system analysis focuses on production of oxygen from lunar regolith through the reduction of ilmenite combined with water electrolysis. Here the application of exergy analysis identifies key opportunities for the use of byproduct heat and the optimal sizing of system components.The studies presented demonstrate the capability of exergy analysis to support the design and integration of electrochemical systems within larger power, ISRU, and ECLS systems supporting space exploration. This approach can enable the full and efficient use of a system’s available work potential based on a consistent, physically meaningful property. Therefore, exergy analysis is shown to be a key tool for the future design and integration of electrochemical systems for space exploration.

Microplasma Ionization of Volatile Organics for Improving Air/Water Monitoring Systems On-Board the International Space Station.

Low molecular weight polar organics are commonly observed in spacecraft environments. Increasing concentrations of one or more of these contaminants can negatively impact Environmental Control and Life Support (ECLS) systems and/or the health of crew members, posing potential risks to the success of manned space missions. Ambient plasma ionization mass spectrometry (MS) is finding effective use as part of the analytical methodologies being tested for next-generation space module environmental analysis. However, ambient ionization methods employing atmospheric plasmas typically require relatively high operation voltages and power, thus limiting their applicability in combination with fieldable mass spectrometers. In this work, we investigate the use of a low power microplasma device in the microhollow cathode discharge (MHCD) configuration for the analysis of polar organics encountered in space missions. A metal-insulator-metal (MIM) structure with molybdenum foil disc electrodes and a mica insulator was used to form a 300 μm diameter plasma discharge cavity. We demonstrate the application of these MIM microplasmas as part of a versatile miniature ion source for the analysis of typical volatile contaminants found in the International Space Station (ISS) environment, highlighting their advantages as low cost and simple analytical devices. Graphical Abstract ᅟ.

Integrated energy and media supply concepts for long-term space missions

In order to minimize the operational cost of future long-term manned space missions, an integrated regenerative energy and media supply system (EMSS) for spacecraft and Space Station is proposed. Based on H 2 O 2 - technology , the first step into a regenerative EMSS could be the integration of the subsystems energy supply, environmental control and life support (ECLS) as well as attitude and orbit control (AOC). Further extension of such a system may also comprise the nutrition system including then further elements as N 2 and C. Electrolyser and fuel cell systems play an important role within EMSS as energy converter while solar dynamic energy supply systems may offer thermal energy in parallel to electricity. Simultaneous availability of thermal and electric energy including adequate storage facilities will form an optimum basis to a variety of different chemical recycling processes as well as media and energy conversion. The motivation for such a technology is presented, the technical characteristics of subsystems technology are summarized and the first approaches of possible concepts are developed. Step by step solutions seem possible so that pilot test plants of low degree of integration may be investigated already in the course of the planned Space Station.

Emergency and rescue considerations for manned space missions

Man in space is totally dependent upon spacecraft systems, particularly those providing Environmental Control and Life Support (ECLS). It is therefore required that the design of manned spacecraft systems include provision for backup emergency and rescue modes of operation to insure adequate crew safety margin. This paper discusses safety, emergency and rescue provisions included in the Space Transportation System (STS), with emphasis on ECLS subsystems. Similar discussion is included for systems projected for use in future, extended duration manned space missions.