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    Analytical Investigation of Surface Temperatures for Different Sized CubeSats at Varying Low Earth Orbits
    (Asme, 2023) Atar, Cihan; Aktas, Metin; Sozbir, Nedim; Bulut, Murat
    Thermal management is a challenging engineering problem for CubeSats due to the limited available volumes restricting the thermal control applications. Therefore, performing thermal modeling and analyses of these small satellites is very crucial for applying proper thermal control measures to maintain safe operating conditions in space. Despite the growing interest in this field, there are still a limited number of studies investigating the thermal behavior of CubeSats. In this paper, surface temperature profiles of 1U, 2U, 3U, 5U, 6U, and 12U sized CubeSats are simulated for varying low earth orbits. The effects of altitudes changing from 400 km to 2000 km and the beta angles changing from 0 to 75 deg are analytically investigated. Not only the coatings with different absorptance and emissivity values but also different amounts of internal heat dissipations are examined to reveal their impact on the thermal balance of satellites. Results demonstrate surface temperatures are highly dependent on those variables. The amount of heat absorbed by satellite panels is affected by the different sizes of CubeSats, different coating properties of panels, and different orbital configurations. The outcomes of this research may be beneficial especially in the early design phase for designing small satellites and selecting proper orbital configurations.
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    Investigation of external heats for cubesats at various low earth orbits
    (Pamukkale Univ, 2023) Atar, Cihan; Aktas, Metin; Sozbir, Nedim
    In this paper, radiative heat loads on structural panels of small satellites are simulated for various orbital configurations. Thermal management of small satellites are challenging because of their limited available volumes. Satellites in orbits experience not only extreme temperatures but also rapid temperature changes. In order to provide safe operating conditions, the thermal environment in space must be carefully analyzed. This paper presents a numerical investigation of thermal environment influenced the panels of satellites for various orbital parameters by using Systema Thermica v4.9.0 software with Monte Carlo Ray Tracing (MCRT) method. The results of this study can be useful in the design stage of small satellites operating in similar orbits.
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    Performance optimization of PEM electrolyzers: An experimental and Taguchi-based approach
    (Pergamon-Elsevier Science Ltd, 2025) Kesercioglu, Muhammed Asim; San, Fatma Guel Boyaci; Sozbir, Nedim; Cay, Yusuf
    In this study, the performance of a proton exchange membrane (PEM) water electrolyzer with an active area of 9 cm2 was investigated under various operating conditions. At the anode, a three-layer titanium cross-mesh along with a fiber felt structure is employed. A total of twenty-seven experiments are conducted according to Taguchi's design of experiments to investigate extremes of operating temperature (40 degrees C, 60 degrees C, 80 degrees C), clamping torque (5 Nm, 7 Nm, 10 Nm), and water flow rates (10, 20, 30 mL/min) on hydrogen production and current density. From these experiments, it was noticed that temperature has the most notable influence by enhancing reaction kinetics and membrane conductivity. Clamping torque improves the electrode-membrane contacts and reduces internal resistance. Water flow rates have an effect on membrane hydration and gas removal, although somewhat less so. The three-layer mesh structure enables effective water distribution and gas evacuation, leading to lower overvoltage and steady operation. The best results came at 80 degrees C, torque of 10 Nm, and flow rate of 10 mL/min. Thus, the findings emphasize the dominant role of temperature and show that clamping torque should not only be regarded as a mechanical factor but also as an electrochemically active design factor in PEM electrolyzer design.
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    Thermal design for a communications satellite payload module
    (Sage Publications Ltd, 2025) Murat, Yunus; Mercan, Hatice; Sozbir, Nedim; Dalkilic, Ahmet Selim
    Satellite design and manufacturing studies have become crucial due to their exposure to extreme thermal conditions in outer space. Thermal management systems are necessary to maintain acceptable temperatures for equipment on satellites' structural panels. Accurate modeling, simulation, and testing are necessary to handle high-gradient temperature cycles, considering worst-case scenarios. The study aimed to design, model, and simulate a geostationary communication satellite using finite element method-based software, analyzing thermal modeling, and extraterrestrial satellites. The literature on controlling satellite temperature is limited, with most studies on cube and nano satellites. No scholarly work combines geosynchronous satellite thermal modeling with finite element analysis, which is crucial for understanding satellite thermal dynamics and solving structural and thermal problems in satellite design. A heat pipe network and MLI are placed on the panel, ensuring a homogeneous temperature distribution. In the worst-case scenario, a 2.8 m2 radiator area is used to eliminate heat dissipation from equipment. Analytical investigation is conducted to assess heat rejection capabilities of payload panels, followed by creation and implementation of reduced thermal mathematical models using commercial software. The worst hot-case analysis shows all equipment remains below upper-temperature limits, with heat pipes preventing excessive hot areas. The worst cold-case analysis requires a heater power of 480 W, with a 50% duty ratio aiming for 960 W. The FEM analysis reveals a duty ratio of 55% for panel heaters. Finally, the thermal design of the satellite can be used to maintain the equipment within its temperature limits.
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    Thermal Investigations of Solar Panel Deployment Angles for a 3U CubeSat Orbiting at LEO
    (Asme, 2024) Atar, Cihan; Aktas, Metin; Sozbir, Nedim; Camdali, Unal
    Designing and manufacturing of CubeSats have a rapidly growing interest lately as they can serve in a wide range of space missions. To ensure that they are safe, stable, and functional in harsh space environment, thermal studies are very important. New design approaches have been introduced to manufacture more efficient and long-lasting satellites, and deploying solar panels is one of them aiming to harness more solar energy. In the literature, however, the studies focusing on CubeSats with deployed solar panels at different angles are very limited. Due to this reason, we investigated the thermal influences of solar panel deployment angle for a 3U CubeSat at low Earth orbit in this study. With this aim, the solar panel deployment angles of 75, 60, 45, 30, 15, 0, -15, -30, -45, -60, and -75 deg were modeled and simulated thermally. Besides, various orbital positions corresponding to different Earth days were examined for the 3U CubeSat with fully deployed solar panels. In addition, the heat absorbed by CubeSat structural panels and its solar panels were analyzed in detail. The results showed that solar panel deployment angles are highly influential on the satellite heating, and hence, maximum heat input occurs at the deployment angle of 15 deg. It can be here noted that our results of this study may give rise to valuable contribution for optimizing the design and energy budget of CubeSats. Furthermore, the available energy harnessed by solar panels can be maximized accordingly.