The thesis primarily investigates the possibility of adapting the high heat capacity displayed by some materials near their melting point, from henceforth called Phase Change Materials (PCM), for their use as a heat sink device aboard small satellites. Theoretically, under their optimum performing conditions not only do PCMs display better behaviour than conventional heat sinks, but they also lower the mass budget required for the thermal control of the spacecraft and its components, while simplifying the whole process of thermal control (by making it passive). However, PCM based heat sinks do have some shortcomings of which low thermal conductivity and high volumetric expansion (during phase change) are particularly significant and which make them difficult to be exploited for space based applications. While the thesis will tackle the problem of low thermal conductivity by the insertion of fins made up of high conductive materials, the problem of volumetric expansion of the PCM will be accounted by leaving a clearance volume in the PCM box (for this study), so as to avoid its failure. Finally to sum it up, the primary goal of the thesis is to validate the concept of PCM as an efficient heat sink device for its use aboard small satellites and to obtain an acceptable coherence between the simulation and experimental results with the intention of possessing the ability to simulate large variations of PCM boxes and to be able optimise one for a given application or mission in the future.
‘Il presente lavoro di tesi si concentra sull’analisi di materiali a cambiamento di fase (Phase Change Materials – PCM) per applicazioni aerospaziali, proponendo una innovativa soluzione tecnologica per il controllo termico di satelliti di piccole dimensioni. In condizioni teoriche ottimali i PCM, infatti, dimostrano non solo di essere molto piú performanti di un radiatore convenzionale ma anche vantaggiosi in termini di massa, consentendo una significativa riduzione del mass budget per controllo termico e quindi permettendo aumentazione della massa a disposizone per il payload. La bassa conducibilitá termica e l’espansione del materiale subita in seguito a fusione – elementi che appaiono proibitivi per un effettivo utilizzo dei PCM in ambito aerospaziale – vengono risolti ricorrendo all’espediente di fins metallici, opportunamente inseriti nella scatola contenente i PCM e lasciando un po di spazio vuoto nella scatola (per questo studio) rispettivamente. L’obiettivo dell’analisi condotta é dunque la validazione della suddetta tecnica adoperata, mostrando una buona corrispondenza tra i risultati numerici e sperimentali ottenuti testando diverse configurazioni di contenitori per i PCM allo scopo di pervenire ad un design ottimale che possa essere implementato in future missioni spaziali
Phase change material as a heat sink device for small satellites
TIWARI, SIDDHARTH SUDHIR
2013/2014
Abstract
The thesis primarily investigates the possibility of adapting the high heat capacity displayed by some materials near their melting point, from henceforth called Phase Change Materials (PCM), for their use as a heat sink device aboard small satellites. Theoretically, under their optimum performing conditions not only do PCMs display better behaviour than conventional heat sinks, but they also lower the mass budget required for the thermal control of the spacecraft and its components, while simplifying the whole process of thermal control (by making it passive). However, PCM based heat sinks do have some shortcomings of which low thermal conductivity and high volumetric expansion (during phase change) are particularly significant and which make them difficult to be exploited for space based applications. While the thesis will tackle the problem of low thermal conductivity by the insertion of fins made up of high conductive materials, the problem of volumetric expansion of the PCM will be accounted by leaving a clearance volume in the PCM box (for this study), so as to avoid its failure. Finally to sum it up, the primary goal of the thesis is to validate the concept of PCM as an efficient heat sink device for its use aboard small satellites and to obtain an acceptable coherence between the simulation and experimental results with the intention of possessing the ability to simulate large variations of PCM boxes and to be able optimise one for a given application or mission in the future.File | Dimensione | Formato | |
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https://hdl.handle.net/10589/95585