Please use this identifier to cite or link to this item: https://hdl.handle.net/10356/151856
Title: Designing with phase change materials for satellite thermal management
Authors: Li, Wen Hao
Keywords: Engineering::Materials::Composite materials
Engineering::Materials::Nanostructured materials
Issue Date: 2021
Publisher: Nanyang Technological University
Source: Li, W. H. (2021). Designing with phase change materials for satellite thermal management. Doctoral thesis, Nanyang Technological University, Singapore. https://hdl.handle.net/10356/151856
Abstract: Due to the harsh environments experienced in space, multiple equipment, and subsystems on board satellites such as electronics, batteries, sensors, and transceivers, require thermal management to stay in the optimal performance temperature. Failure of any equipment could spell doom to the satellite mission, leading to huge loss of investments. Therefore, the thermal management system (TMS) on-board satellites are crucial for mission success. Conventional satellites have a greater luxury of power, on-board volume, and mass to house heavy, bulky, and power hungry TMS. Small satellites, or smallsats, that are typically less than 200 kg, do not have such luxuries. With limited resources, TMS on smallsats needs to be power efficient, compact in size and lightweight. Therefore, power passive TMS, are favoured over active TMS. The state of the art smallsat passive TMS include multilayer insulation, sun shields, paint coating, thermal louvers, flexible thermal straps, passive heat pipes, deployable radiators, and thermal storage units (TSU). Out of the passive TMS, TSU powered by solid-liquid phase change material (PCM) is an attractive solution which can provide long term temperature damping. Solid-liquid PCMs release and absorb large amount of stored heat at a relatively constant temperature when they melt and freeze, respectively. This temperature regulatory nature potentially enables TSU to substitute both the heating and cooling TMS of an equipment, hence freeing up volume on board and decrease overall cost. PCM have also been extensively researched on for a variety of applications. In this thesis, PCM enhanced with high thermal conductivity three-dimensional graphene (3D-C) micro-skeletal and carbon fibre honeycomb (CH) was developed and tested as potential PCM-based TSU. Paraffin PCM have application in space as early as 1970s on the apollo lunar rover. Paraffins are highly suitable for space application as they have low outgassing, high thermal cycling stability, high energy density and a variety of melting temperatures available for application, and are non-toxic, non-corrosive, and compatible with metallic and carbon-based materials commonly used on satellites. However, the poor thermal conductivity of paraffins, which results in slow heat spread, large thermal gradient within PCM and often insufficient temperature damping in equipment have greatly restricted their potential application and development, on this otherwise a great solution. Researchers have studied metallic and carbon allotrope inclusions for thermal conductivity enhancement of a PCM. Carbon allotropes have the advantage over metallics with their lower density and hence displacing less PCM when infused. Therefore, in this thesis, highly porous 3D-C and structurally sturdy CH are infused with PCM to form PCM composites with improved performances. These PCM composites are studied extensively to develop them for space application. Studies in literature have been conflicted whether percolating discrete fillers or three-dimensional scaffolds are the better solution to improve the thermal conductivity of PCM. Therefore, first and foremost in this thesis, a systematic study is conducted between 2 samples of paraffin PCM infused with, respectively, interconnected 3D-C and discrete graphene powder (GP) derived from 3D-C and in the same mass fraction, to determine the better solution with respect to smallsat application. It is observed that PCM sample infused with 3D-C (3DCPCM) has a significantly better shape stabilization over thermal cycling and a higher thermal conductivity improvement over neat PCM of 300% than PCM sample infused with GP (GPPCM), where thermal conductivity improvement over neat PCM was only 60%. The interconnected network 3D-C in 3DCPCM is found to spread the ullage that will otherwise have formed in the PCM sample, as observed in GPPCM and neat PCM samples. Hence interconnected 3D-C is shown to be superior to the discrete GP to improve the thermal conductivity of PCM. Subsequently, 3D-C of various densities (12.5 – 74.7 mg/cm3) are synthesized and infused in PCM to study the effects of 3D-C loading on thermal conductivity and latent heat of fusion of 3DCPCM. It is observed that the thermal conductivity of 3DCPCM increases with 3D-C density. A model is formulated using experimental results and the theory proposed by Ashby to predict the thermal conductivity of 3DCPCM using the density of 3D-C. To determine the suitability of the PCM composite with use-case heat inputs, a demonstrator test bench setup is built. The test bench can concurrently test up to 4 different PCM composites in identical packaging with the same heat load. Performance is analysed based on a series of figure of merits (FOMs). 4 identical packaging, respectively filled with 3DCPCM, CH+3D-C infused with PCM (CH3DCPCM), CH infused with PCM (CHPCM) and neat PCM were tested simultaneously, at 3 use-case heat loads of 20, 15 and 10 W. It was found that CH3DCPCM and 3DCPCM significantly outperformed the other samples, with CH3DCPCM performing 10 – 40% better than 3DCPCM based on the FOMs. Finally, to qualify 3DCPCM and CH3DCPCM for space, both sample in packaging were tested in two space environment tests: launch vibration and extreme temperature thermal cycling. The vibration test is conducted in operation conditions with PCM in the liquid state during the test. The results show that both samples retain their pre-test performance, hence showing that 3D-C structure can retain its structural integrity in launch vibration conditions in a liquid medium. The results of the extreme temperature thermal cycling show CH3DCPCM has a lower performance degradation as compared to 3DCPCM. It is interesting to note that CH3DCPCM post-test performs better than 3DCPCM pre-test, indicating both the significantly better performance of CH3DCPCM over 3DCPCM and the high resistance to extreme temperature cycles of CH3DCPCM.
URI: https://hdl.handle.net/10356/151856
DOI: 10.32657/10356/151856
Schools: School of Mechanical and Aerospace Engineering 
Organisations: Thales Solutions Asia Pte Ltd
Thales Alenia Space
Research Centres: Satellite Research Centre 
S4TIN
Rights: This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).
Fulltext Permission: open
Fulltext Availability: With Fulltext
Appears in Collections:MAE Theses

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