Considered technologies are: • mobile alkaline electrolyte systems conventional advanced • immobile alkaline electrolyte systems • proton exchange membrane (PEM) systems. For mobile alkaline electrolyte (KOH) electrolyzers as well as for fuel cells a very wide knowhow exists in Europe for terrestrial applications. A big advantage of this technique is the easy and efficient heat- and water management. An interesting variant is the ELOFLUX technique, which allows a very compact and lightweight design. Furthermore, the gas/electrolyte separator inside the electrodes could be an important characteristic for space application. Immobile alkaline electrolyte systems, which are already used for space application in the US are, due to the very high efficiencies, of great interest for space application in Europe, too. The European experience on these systems is growing. In the field of PEM technologies new membrane developments and improved designs led to good efforts. This system also has good opportunities for space application. A comparison of the characteristics, advantages and disadvantages of the different systems concerning their application in space will be given. Mass and volume of all components and storage units, efficiencies, heat- and water management, behaviour under «-g environment, during launch and re-entry, lifetime, reliability, maintenance as well as safety aspects will be regarded. The comparison will also include comparable battery systems. An important aspect of comparison will be the required power level, the duration and load profile of the space mission. A combination with other systems, e.g. life support for long-term missions or lunar basis will be discussed. (Paper number IAF-ICOSP89-6-1.) 6-4. Development of Closed Brayton Cycle Engine for Solar Power LOX/LH? Production System K. Kishimoto & M. Yasui Mitsubishi Heavy Industries, Ltd., 1200 Higashitanaka, Komaki-city, Aichi-pref., Japan. As we reported in IAF-87-253, we (Mitsubishi Heavy Industries, Ltd.) are now in the process of developing the LOX/LH2 production system. High pressure ratio closed Brayton cycle technology is essential for this program. We have been developing the scaled closed Brayton cycle engine as research and development in-house. Recently we finished the first phase of the program. The paper will describe our experience and test the results of this first phase. (Paper number IAF-ICOSP89-6-4.) 6-5. Considerations of Power Conversion Techniques in Future Space Applications Praveen Jain, J. Bottrill & M. Tanju Canadian Astronautics Ltd., 1050 Morrison Drive, Ottawa, Ontario K2H 8K7, Canada. This paper presents some advanced concepts of DC/AC, DC/DC and AC/DC power conversion for high power space applications. Main design driving factors for these types of power conversion are presented. For high power applications, the resonant mode converters offer high efficiency, low mass and volume, reduced EMI, and high reliability. For DC/AC power conversion three types of resonant inverter configurations—parallel, series-parallel and hybrid—are investigated. Two basic control techniques, phase shift and pulse
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