Browsing by Author "Cho, Wei-Lin"
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Item Development of a Mechanical Pump-Assisted Active Two-Phase Thermal Control System (MPA2PTCS) for High Power Satellite(2024 International Conference on Environmnetal Systems, 2024-07-21) Cho, Wei-LinHigh-throughput satellite (HTS) provides more throughput than a classic fixed satellite service (FSS), usually by a factor of 20 or more, for the same amount of allocated orbital spectrum, thus significantly reducing cost-per-bit. With the upward trending of the telecommunication satellite capability, the power consumption of the payload electronics, and thus the required heat rejection capability, has increased tremendously in the past decade. The power consumption for high throughput satellite can be upward to 25 kW. Passive two-phase (heat pipe, loop heat pipe, etc.), single-phase pump loop, and mechanical pump-assisted active two-phase thermal control system (MPA2PTCS) have been used in addressing the satellite thermal management issues. For high heat load, high heat flux, and long transport distance application, the passive two-phase and single-phase pump loop have reached their limits. Recent developments have shown that the MPA2PTCS is very promising in offering thermal management for HTS market. Additionally, MPA2PTCS has better architecture flexibility and better tolerance to late-stage design change. Compared to the single-phase thermal control system, the MPA2PTCS offers better temperature uniformity, lower pumping power, and potentially lighter system mass. With these benefits, the prospect of deploying two-phase thermal control technology in high power spacecraft is very promising. Collins Aerospace has been working on the development of an experimental high power MPA2PTCS for geosynchronous satellite. This MPA2PTCS consists of a pump, multiple evaporators, multiple condensers, and a two-phase accumulator. The operating principle of the MPA2PTCS and the performance of each component will be reviewed in this paper. Other performance-enhanced components such as recuperator, sub-cooler, and gas trap for the future MPA2PTCS will also be reviewed.Item Mechanically Pumped Two-Phase Flow Loop Evaporator Development and Performance Evaluations(50th International Conference on Environmental Systems, 7/12/2021) Cho, Wei-Lin; Adamson, GaryTwo-phase flow loop offers unique benefits in spacecraft thermal control system. Compared to the passive thermal control, the two-phase flow loop is more suitable for high heat load, high heat flux, and long transport distance applications. Additionally, it has better architecture flexibility and better tolerance to late stage design change. Compared to the single phase thermal control system, the two-phase flow loop offers better temperature uniformity, lower pumping power, and lighter system mass. With these benefits, the prospect of deploying two-phase thermal control technology in high power spacecraft is very promising. In general, there are four major components in the two-phase flow loop; a pump, an evaporator, a radiator/condenser, and a two-phase accumulator. In addition to these hardware, the development of the two-phase thermal control system architecture and system control scheme also play equally important roles in ensuring the system robustness. Collins Aerospace has been working on the two-phase thermal control technology development in the past few years. One of the efforts was to develop an evaporator with the features of high heat load/flux capability, minimum pumping power consumption, light weight structure, and high scalability. This paper reviews the test apparatus and the performance of the evaporators. The heat load was varied from 1,000 W to 8,000 W and the heat flux was varied from 6.5 W/cm2 to 22.6 W/cm2. The heat load was applied to the top, the bottom, or both sides of the evaporator. Water was used as the working fluid and the quality was controlled in the range between 0.1 and 0.8. Using the evaporator interface and outflow temperatures as references, with quality of 0.5 and single-sided heat load of 3,500 W, the 2-inch wide by 12-inch long evaporator thermal resistance is 7.0 x 10-5 �C-m2/W and the hydraulic power is 0.016 W.Item Parker Solar Probe Solar Array Cooling System In-Orbit Performance Review(49th International Conference on Environmental Systems, 2019-07-07) Cho, Wei-Lin; Miller, Christopher; Zaffetti, Mark; Hansen, Harold; Sears, Patrick; O'Neill, Jonathan; Bechard, Eric; Stewart, GaryAfter years of development, Parker Solar Probe (PSP) was launched on August 12, 2018 starting its seven-year journey to unveil the long-sought mystery of our solar system. The in-situ measurements and imaging, powered by a pair of solar array wings, will be used to understand how the sun's corona is heated and how the solar wind is accelerated. As the PSP orbits close to the sun, the cooling system removes the excess heat from the solar cells to prevent them from overheating. UTC Aerospace Systems (UTAS) started the development of the Solar Array Cooling System (SACS) in late 2008. After extensive studies, a single phase mechanical pump flow loop with water as the working fluid was selected due to the unique operating environment of the PSP. Although it is an excellent heat transfer fluid, water has a major disadvantage: its high freezing point. A unique operating strategy involving two activations and multiple hot slews was developed to prevent the water from freezing throughout the whole mission. The PSP SACS hardware includes two pumps and two motor controllers (one primary and one redundant), one accumulator, two Solar Array Platens (SAPs), four Cooling System Primary Radiators (CSPRs), three isolation valves, three service valves, and instruments. In November 2013, the PSP SACS completed the half scale thermal vacuum tests and achieved TRL 6 advancement. The subsequent full scale SACS thermal-vacuum test and the post-integration observatory level thermal-vacuum test were completed in March 2017 and February 2018, respectively. The PSP SACS has been operating successfully through four major operating points; the first activation, trajectory correction maneuvers, the second activation, and the first perihelion. This paper reviews PSP SACS hardware, the responses of PSP SACS at the aforementioned four operating points, and the overall performance of the PSP SACS in its early mission.