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Japan Aerospace Exploration Agency (JAXA) is now developing polymer electrolyte fuel cell (PEFC) systems that can be applied to the high altitude balloon, transfer vehicle, and space craft. We designed the fuel cell system for low pressure environment where the working gases were supplied by the counter-flow method and the temperature of the system was passively controlled by the heat generated from the fuel cell stack. We assembled the system and are testing its performance under the thermal vacuum conditions. Furthermore, we started the development of a fuel cell system which can be operated by the propellants for spacecraft. We tried to operate the fuel cell using Hydrazine and Nitrogen Tetra Oxide. Through our measurements, stable generation of electricity was observed using PEFC. We also tried to measure the performance of the PEFC using the propellants with additives in order to decrease the melting point of the propellants., 資料番号: AA0049500056, レポート番号: JAXA-SP-06-006

We clarified the criteria for 100 W-class operation of the fuel cell system. We tested the fuel cell performance by the operation under low pressure condition (approximately 3 kPa). We operated the fuel cell without external humidifier and thermal controller. Though these operations, we confirmed the operational conditions by the passive control of the fuel cell system under low pressure condition., 資料番号: AA0049500060, レポート番号: JAXA-SP-06-006

The heat and moisture exchanger (HME) is a piece of medical equipment use for patients who cannot breathe voluntarily. The evaluation of HME is performed under ISO system; however, it includes that there exists a temperature distribution in a model system as well as temperature of the air to HME is required to be 23±1℃ although this temperature may be different in each hospital. Because HME is necessary to change once a day with no insurance, this could be a major burden for patients who are hospitalized for a long term. In this study, 1) basic trials were made in order to equalize the temperature in the model system, 2) examinations were made for the air with various temperatures to HME, and 3) development of a warmer to extend use of HME were conducted. The installation of a small fan made it possible to equalize the temperature in model system. The influence of a temperature of the air to a HME in the range of 2.9~37.5 ℃ may be very crucial. Performance of HME was improved by introducing a warmer that covers entire HME device.

Water balance of the closed-type transplant production system with artificial lighting was investigated. Sweetpotato (Ipomoea batatas (L.) Lam. cv. Beniazuma) plants were grown for 15 days at photosynthetic photon flux (PPF) on the tray surface of 100, 200 and 300μmol m^ s^ on days 0-2, 3-11 and 12-14, air temperature of 30℃, CO_2 concentration of 1000μmol mol^, relative humidity of 80/100% (photoperiod/dark period) inside the system and photoperiod of 16 h d^. Daily amounts of evapotranspirated and dehumidified water were increased with time due to increases in evapotranspiration area and PPF. Daily amount of dehumidified water was 90-950f the sum of evapotranspirated and humidified water. The amounts of irrigated, evapotranspirated, humidified and dehumidified water during the experiment were 49.5, 36.7, 24.3 and 55.9kg m^, respectively. Water contents of plants and soil at the end of the experiment were 1.6 and 10.8kg m^, respectively. Water utilization efficiency of the system was 0.93. These results show the amount of water use for transplant/plant production can be decreased to 24% the amount of irrigated and humidified water when dehumidified water was reused for irrigation and humidification. Thus, the closed-type transplant production system is suitable for minimizing the water use in transplant/plant production.

Water balance of the closed-type transplant production system with artificial lighting was investigated. Sweetpotato (Ipomoea batatas (L.) Lam. cv. Beniazuma) plants were grown for 15 days at photosynthetic photon flux (PPF) on the tray surface of 100, 200 and 300μmol m^ s^ on days 0-2, 3-11 and 12-14, air temperature of 30℃, CO_2 concentration of 1000μmol mol^, relative humidity of 80/100% (photoperiod/dark period) inside the system and photoperiod of 16 h d^. Daily amounts of evapotranspirated and dehumidified water were increased with time due to increases in evapotranspiration area and PPF. Daily amount of dehumidified water was 90-950f the sum of evapotranspirated and humidified water. The amounts of irrigated, evapotranspirated, humidified and dehumidified water during the experiment were 49.5, 36.7, 24.3 and 55.9kg m^, respectively. Water contents of plants and soil at the end of the experiment were 1.6 and 10.8kg m^, respectively. Water utilization efficiency of the system was 0.93. These results show the amount of water use for transplant/plant production can be decreased to 2427777710660f the amount of irrigated and humidified water when dehumidified water was reused for irrigation and humidification. Thus, the closed-type transplant production system is suitable for minimizing the water use in transplant/plant production.