Simulação térmica e geração de energia de um CubeSat

Abstract

CubeSat is a standard satellite based on the dimensions of a cube with 10 × 10 × 10 cm, about which academia and industry have already carried out several successful missions in the last decade and still have significant growth potential in the coming years. In space, these small satellites must survive in the vacuum environment, with intense temperature variation and thermal gradient, usually above 60◦C and, in a few minutes, below -30◦C. One of the critical subsystems of CubeSat is thermal control, which maintains temperature stability between the operational bands of the subsystems. Another equally critical subsystem is the power system, responsible for generating electrical energy used during the orbit. This dissertation focuses on the thermal and power simulation of a typical CubeSat 1U. The heat transfer simulation is divided between the irradiance and thermal models. The irradiance model determines the magnitude of heat sources, which are made up of solar radiation, albedo, and infrared emission from the earth; such sources depend on the attitude model (Pointing of CubeSat), orbit (orbital dynamics), and altitude (vertical distance). From the variation of the model, different thermal scenarios faced by CubeSat along the orbit are investigated. Then, to investigate heat transfer in space, a thermal model based on the Finite Volumes Method (FVM) is structured, using the irradiance model as a contour condition on the external surfaces of the solar panel. In total, five orbits are simulated: maximum solar exposure with eclipse (MES-0), maximum sun exposure without eclipse (MES-90), detumbling with eclipse (DET-0), detumbling without eclipse (DET-90), and maximum exposure to the eclipse coupled to a heat tube (MES-0-HP). In addition, recognizing that heat is an energy source, this work simulates a thermoelectric generator (TEG) coupled to the CubeSat, evaluating the potential of TEG for power generation. The results indicate that the different scenarios of the orbit impact the power generation and thermal control of CubeSat, being essential to predict the thermal conditions for the design of small satellites. During thermal simulations, a heat tube (HP) between solar panels is considered in the model, improving the power generation and performance of the photovoltaic panel and thermoelectric generator, compared to simulations without the heat pipe. However, the simulations show that the power of the thermoelectric generator is still low. In addition, the simulations show the impact of contact resistances (RTC) on the temperature and power generation of CubeSat.