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Browsing by Author "Carvalhais, Daniel Campanudo"

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  • Thermal Modelling and Experiments for Small Satellites
    Publication . Carvalhais, Daniel Campanudo; Brojo, Francisco Miguel Ribeiro Proença; Figueiredo, Paulo de Vasconcelos; Guerra, André Gomes da Costa; Machado, Miguel Sousa
    There has been an increasing interest in CubeSat missions due to its small size, low cost and flexibility to accommodate different payloads. New missions with highly temperature sensitive payloads, increased power dissipation (by continuous miniaturization of electronic components and systems) and reduced radiating surfaces lead the thermal loads issues into a bigger challenge. One of the causes of failure in a satellite in space is the temperature peaks suffered during a full orbital cycle. Therefore, proper thermal control system design and test should be performed to guarantee the reliability of a spacecraft prior to launch. 3-AMADEUS is a unity CubeSat currently being developed in a partnership between CEiiA and UBI. The purpose of this mission is to demonstrate that a attitude determiner and control system exclusively magnetic is able to provide a three axis orbital attitude for the nanosatellites. The present work aims to perform thermal analysis to 3-AMADEUS CubeSat in order to ensure its survival as soon as it is placed in orbit. Therefore, it is required the understand the main heat transfer processes within a satellite, conduction and radiation, in order to validate the current methodologies used for thermal analysis. Hence, with the purpose of developing thermal models with higher reliability, two experiments were devised to be performed in a vacuum environment. The first experimental test consists in a study of heat exchange between two aluminum plates through radiation, using an infrared lamp as a heat source. Three distance configurations between plates and two lamp types were tested to comparison. This would emulate, for example, the heat transmission between different components within the satellite. Regarding the conduction experiment, most nano and micro satellites are composed of stacked PCBs, held together by spacers and rods and linked to the main structure. This is the primary mean to conduct the heat from the different components to the external radiating surfaces. A high thermal resistance is associated with the interface between the PCB and the spacers, which is an unknown parameter with a high impact on the thermal analysis. Therefore, a second experiment is carried out to study thermal contact resistance (or conductance) between them. In parallel, finite element software (MSC Nastran) is used to carry out a numerical study of the same experiments. The temperature distribution results of both numerical and experimental solutions were then compared, and the results were discussed. It was concluded that the results obtained in both experiments, in general, presented a good agreement. Finally, with the results obtained in the numerical simulations and using the validated methodology, a steady state thermal analysis was performed to 3-AMADEUS
    2019-12-10Master thesis Open access Show more