University of Twente Student Theses
Lunar Water Extraction : Design, Optimization, and Development for Future Space Exploration
Heitkamp, M.J.F. (2024) Lunar Water Extraction : Design, Optimization, and Development for Future Space Exploration.
|
PDF
19MB |
| Abstract: | Major strides in space technology and exploration have confirmed the presence of water on the Moon, a discovery that has profound implications for sustaining human life and supporting a long-term space environment. Water is vital not only for human survival but also for its potential to generate rocket fuel through electrolysis, a process that separates water into hydrogen and oxygen, which are key components for propulsion. Lunar water exists both as isolated molecules and in the form of ice within the regolith, making it a crucial element of ISRU strategies aimed at creating self-sufficient Lunar bases and enhancing the feasibility of long-term space missions. The extraction of water from lunar ice involves complex processes, including sublimation, deposition, and liquefaction, each presenting unique challenges. These phase changes must be managed under the extreme conditions of the Moon’s environment, where minimal atmospheric pressure, significant temperature variations, and specific material properties can affect the efficiency of water capture and subsequent storage. Strategies for water extraction need to be meticulously designed to address these challenges, ensuring that the transitions between phases are optimised for maximum efficiency and effectiveness. Sublimation, the process in which solid ice transitions directly to water vapour, poses particular challenges on the Moon due to the extremely low atmospheric pressure. In such an environment, sublimation occurs at a much slower rate unless temperature control is carefully optimised. A key strategy to overcome this challenge involves stirring the icy-regolith mixture, which promotes better heat distribution throughout the sample. As the regolith moves, its effective thermal conductivity increases, leading to faster heat transfer and faster sublimation. The increased particle interactions that result from stirring contribute to a higher sublimation rate. However, the magnitude of these rates does not lead to significant pressure build-up, as even at the maximum sublimation rates, the operational pressures remain below the triple point of water (611.73 Pa). This ensures that the water remains in the vapour phase, preventing unwanted phase transitions. The results summarised in table 10.1 demonstrate the time and maximum rates of sublimation, deposition, and liquefaction under different operational conditions. Sublimation, powered by constant heating, achieves a maximum rate of 252 g/h after 16.4 hours. While this is effective, the challenge of managing the delicate balance between temperature and pressure remains. Deposition, the reverse of sublimation, where vapour directly transitions into solid ice, was successfully optimised in the cold trap. By carefully tuning the control parameters, the highest deposition rates were achieved, ensuring that the cold trap could match the high sublimation rates from the earlier stage. The 1D model used for this process showed expected behaviour, with the deposition rate stabilising at approximately 50 grams per hour before gradually approaching zero after about 0.7 hours. Given the significant discrepancy between the sublimation and deposition rates, the current cold trap design requires modification. By implementing a larger control volume to mitigate the effects of free molecular flow, the efficiency of connecting sublimation to deposition would be enhanced, leading to optimal water vapour capture. This phase is crucial to ensure that once the maximum ice growth is reached, the delamination process can begin. During delamination, only 7% of the initially deposited ice is lost through sublimation, allowing the Liquefaction, the transformation of solid ice back into liquid water, proved to be an efficient process, even at low heat fluxes. The time required for liquefaction was relatively short compared to the time needed to heat the ice to the required phase transition temperature. However, achieving this phase transition more efficiently can be further improved by increasing the power input during liquefaction or enhancing the thermal properties of the liquefaction chamber. One effective solution involves polishing the copper inlay inside the chamber to increase its surface emissivity, which improves heat transfer and accelerates the liquefaction process. Overall, these results highlight the successful management of sublimation, deposition, and liquefaction processes, even under the extreme conditions of the Lunar environment. The optimised strategies not only enhance the efficiency of water extraction but also provide valuable insights for the development of future systems aimed at harvesting water from the Lunar surface. The continuous refinement of these processes, particularly through careful control of heat fluxes and surface properties, promises to further improve the performance of water extraction systems, ensuring their viability for long-term Lunar exploration. remaining 93% to be retained in the liquefaction chamber for subsequent processing. |
| Item Type: | Essay (Master) |
| Faculty: | ET: Engineering Technology |
| Subject: | 30 exact sciences in general, 31 mathematics, 33 physics, 38 earth sciences, 39 astronomy, 46 veterinary medicine, 48 agricultural science, 50 technical science in general, 52 mechanical engineering, 57 mining engineering, 58 process technology |
| Programme: | Mechanical Engineering MSc (60439) |
| Link to this item: | https://purl.utwente.nl/essays/104609 |
| Export this item as: | BibTeX EndNote HTML Citation Reference Manager |
Show download statistics for this publication
Show download statistics for this publicationRepository Staff Only: item control page