Session
Technical Poster Session 13: Thermal
Location
Utah State University, Logan, UT
Abstract
Satellite manufacturers and customers continue to trend toward higher power, duty cycle-driven components (high powered amplifiers) to get the most capability out of each small/CubeSat put in orbit. The result is more waste heat to manage, requiring engineers to develop a means of transferring or storing the energy without causing a substantial increase in thermal management system mass. Phase Change Material (PCM) heat sinks are being utilized by the industry as a solution to this challenge due to their fully passive operation and ability to reduce the mass of the thermal management system. PCM heat sinks for duty cycle applications are intended to absorb waste heat during operation, then utilize the dormant period of the orbit to fully dissipate the energy stored. This time-averaged dissipation allows the radiator panel to be designed for the average heat load rather than the peak value, resulting in significant surface area reduction in most applications. PCM heat sinks can also reduce the magnitude of temperature cycles, which can also reduce the severity of solder/bond line stresses that may accumulate as fatigue damage during cyclic operation. The construction of PCM heat sinks typically employ an aluminum enclosure with an internal conductivity enhancing (fin/foam/lattice) structure with the PCM encapsulated within. The internal conductivity-enhancing structure design of the heat sink and PCM selection must be optimized together to enable high performance, as the PCM material has relatively low thermal conductivity. Furthermore, because the PCM is chosen specifically for its material properties, it is imperative that the PCM retains these properties throughout the repeated melt/solidify cycles that it will experience during use. This is especially true for satellite and space applications where the PCM may see thousands of cycles due to orbital operational profiles. As such, designers in these markets must also focus on qualification of the design across long time periods with many cycles. Long term stability of common paraffin wax (or alkanes PCMs have been verified experimentally) through thousands of operational cycles. Two common hydrocarbon PCMs, Octadecane and Eicosane, have been subjected to over 10,000 phase change cycles and the results are presented here.
Passive Thermal Storage of Small Satellites for SWaP Improvements Over Thousands of Operational Cycles
Utah State University, Logan, UT
Satellite manufacturers and customers continue to trend toward higher power, duty cycle-driven components (high powered amplifiers) to get the most capability out of each small/CubeSat put in orbit. The result is more waste heat to manage, requiring engineers to develop a means of transferring or storing the energy without causing a substantial increase in thermal management system mass. Phase Change Material (PCM) heat sinks are being utilized by the industry as a solution to this challenge due to their fully passive operation and ability to reduce the mass of the thermal management system. PCM heat sinks for duty cycle applications are intended to absorb waste heat during operation, then utilize the dormant period of the orbit to fully dissipate the energy stored. This time-averaged dissipation allows the radiator panel to be designed for the average heat load rather than the peak value, resulting in significant surface area reduction in most applications. PCM heat sinks can also reduce the magnitude of temperature cycles, which can also reduce the severity of solder/bond line stresses that may accumulate as fatigue damage during cyclic operation. The construction of PCM heat sinks typically employ an aluminum enclosure with an internal conductivity enhancing (fin/foam/lattice) structure with the PCM encapsulated within. The internal conductivity-enhancing structure design of the heat sink and PCM selection must be optimized together to enable high performance, as the PCM material has relatively low thermal conductivity. Furthermore, because the PCM is chosen specifically for its material properties, it is imperative that the PCM retains these properties throughout the repeated melt/solidify cycles that it will experience during use. This is especially true for satellite and space applications where the PCM may see thousands of cycles due to orbital operational profiles. As such, designers in these markets must also focus on qualification of the design across long time periods with many cycles. Long term stability of common paraffin wax (or alkanes PCMs have been verified experimentally) through thousands of operational cycles. Two common hydrocarbon PCMs, Octadecane and Eicosane, have been subjected to over 10,000 phase change cycles and the results are presented here.
