Tajmar, Martin
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Tajmar, Martin
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Tajmar, Martin
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Tajmar, M.
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Item-typ:Veröffentlichung, Challenges and opportunities of green propellants and electric pump feeding for future european kick stages(Springer International Publishing, 2022); ; ; ; This paper analyses the synergy between two innovative technologies: green propellants and electric pump feeding, for a 500 N engine thrust range. The novel approach is then compared to the legacy configuration, i.e., an MMH/NTO pressure fed system. First, a discussion of the benefits and challenges of the different technologies is presented. Subsequently, the proposed configuration relying on green propellants and e-pumps is investigated. After selecting hydrogen peroxide as the baseline oxidiser, a comparative analysis of different fuel candidates is conducted, leading to the selection of propane as fuel. Furthermore, the second part of the paper weights the novel configuration against the standard one and confronts their propulsive performance and mass budget. Results show that the implementation of electric pump feeding can leverage the performance of the selected green propellant outpacing the conventional solution.Wissenschaftlicher ArtikelBand:101Heft:398 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Yield of dwarf tomatoes grown with a nutrient solution based on recycled synthetic urineExtended human spaceflight missions require not only the processing, but also the recycling of human waste streams in bio-regenerative life support systems, which are rich in valuable resources. The Combined Regenerative Organic food Production® project of the German Aerospace Center aims for recycling human metabolic waste products to produce useful resources. A biofiltration process based on natural communities of microorganisms has been developed and tested. The processed aqueous solution is, among others, rich in nitrogen present as nitrate. Nitrate is one of the main nutrients required for plant cultivation, resulting in strong synergies between the developed recycling process and plant cultivation. The latter is envisaged as the basis of future bio-regenerative life support systems, because plants do consume carbon dioxide, water and nutrients in order to produce oxygen, water, food and inedible biomass. This paper describes a series of plant cultivation experiments performed with synthetic urine processed in a bioreactor. The aim of the experiments was to investigate the feasibility of growing tomato plants with this solution. The results of the experiments show that such cultivation of tomato plants is generally feasible, but that the plants are less productive. The fruit fresh weight per plant is less compared to plants grown with the half-strength Hoagland reference solution. This lack in production is caused by imbalances of sodium, chloride, potassium, magnesium and ammonium in the solution gained from recycling the synthetic urine. An attempt on adjusting the produced bioreactor solution with additional mineral fertilizers did not show a significant improvement in crop yield.Wissenschaftlicher ArtikelBand:2094 99