Lead Center: JSC Participating Center(s): GRC, GSFC, JPL, MSFC Scope Title: Spacecraft Thermal Management Scope Description: NASA seeks new technologies that will facilitate low-mass and highly reliable thermal control systems for the exploration of our solar system. This solicitation specifically targets proposals for new technologies and methods that clearly address one of the following areas: Lunar surface habitat thermal technologies High-temperature heat acquisition and transport for nuclear electric propulsion (NEP) Topology optimization of thermal control systems These areas are considered of equal priority, and no award preference is expected for one area over another. 1. Lunar Surface Habitat Thermal Technology Development NASA is seeking focused efforts to develop thermal control technologies that will enable crewed habitats for extended stays on the lunar surface. Technologies should address a gap associated to long-duration habitation on the lunar surface, where temperatures range from -193 C or lower in shadow regions (including night) to 120 C at the equatorial subsolar point. Technologies are needed that allow a single mobile habitat to operate in all these environments. Technologies should address reduction in mass, volume, and power usage relative to current solutions. The addition of heaters can lead to increased vehicle mass due to additional power generation and storage requirements and is not considered a novel architecture approach. Proposed radiator technologies should also address micrometeoroid and orbital debris (MMOD) robustness and protection potential where appropriate. Examples of other challenges to address in this area include the deposition of dust on radiators leading to degraded optical properties, contamination-insensitive evaporators/sublimators to enable long mission life, self-healing coolant tubes for MMOD-impact resilience, and passive gas traps for removing gas bubbles from internal thermal control system loops that use low-surface-tension non-water coolants. Technologies should be suitable for use with habitats having variable heat loads averaging between 2 and 6 kW. All technologies should support a minimum operational duration of 5 years and be compatible with encountered environments. Alternatively, technologies that utilize the conditions provided by the lunar environment to provide a critical function may also be considered; for example, air-water separator technologies that leverage the gravity field of the lunar surface, or concepts that explore the viability of utilizing the lunar surface regolith to provide long-duration thermal control function. As appropriate, such systems should also address functional capability in the microgravity environment that will be experienced prior to lunar surface operations. 2. High-Temperature Heat Acquisition and Transport for Nuclear Electric Propulsion (NEP) NASA is seeking the development of thermal transport systems for NEP. This application requires the transfer of large amounts of thermal energy from a nuclear reactor to a power conversion system. NASA desires a high-temperature heat transfer system capable of transferring 4 to 10 MW of thermal power from a nuclear reactor, at a supply temperature of 1,200 to 1,400 K and a flux on the order of 0.3 MW/m2 with a goal of 1 MW/m2, to the hot-end heat exchangers of an electric power conversion system. The target distance for the power conversion system is 5 m from the reactor, but transport distances up to 10 m may be required. The system will need to be gamma- and neutron-radiation tolerant, be single-fault tolerant (a single leak should not render the system inoperable) and have an operating life of 15+ years. System mass and reliability should be addressed as part of the proposal. Example solutions include, but are not limited to, liquid metal heat pipes or pumped fluid loops. Special consideration should be given to interfaces (both at the nuclear reactor and at the power conversion system) to maximize heat transfer. Integration with the reactor may include solutions that run through the reactor core. For integration with the power conversion system, a helium-xenon working fluid in a Brayton cycle system may be assumed but is not required. 3. Topology Optimization of Thermal Control Systems Advanced design and manufacturing are rapidly transforming engineered systems. The advent of reliable additive manufacturing techniques coupled with robust optimization algorithms is facilitating the development of new high-performance systems. To date, the advanced design community has primarily focused on optimized structural systems that minimize mass and volume while meeting structural performance requirements. While some work has been done to develop advanced design tools for thermal control systems, considerable work remains to make it standard practice. This solicitation requests the development of a topology optimization (TO) tool that can optimize a thermal-fluid component (e.g., a heat exchanger). Specific goals include minimizing component (heat exchanger) mass, minimizing pressure drop, and maximizing heat transfer efficiency. Because of the inherent multiphysics characteristics of the problem (coupled structural/thermal/fluids behavior), proposals are encouraged to leverage existing TO software (e.g., see Watkins (2019) and other TO references below) that can already handle structural and thermal conduction optimization, and extend the code to handle systems that include single-phase laminar convective heat transfer. This solicitation requests the development of TO software capable of minimizing heat exchanger mass while meeting envelope volume, heat transfer, and pressure drop targets. The initial target is optimization for laminar single-phase flow. An extended goal is to be able to optimize a heat exchanger for turbulent single-phase flow while accommodating manufacturing constraints to ensure the heat exchanger design is manufacturable. Expected TRL or TRL Range at completion of the Project: 3 to 5 Primary Technology Taxonomy: Level 1: TX 14 Thermal Management Systems Level 2: TX 14.2 Thermal Control Components and Systems Desired Deliverables of Phase I and Phase II: Analysis Prototype Hardware Software Desired Deliverables Description: Phase I awards in this area are expected to demonstrate analytical and/or empirical proof-of-concept results that demonstrate the ability of the organization to meet the goals stated in the solicitation. At the conclusion of a Phase II contract, deliverables are expected to include a functioning prototype (or better) that demonstrates the potential to meet the performance goals of the technology or software. Any delivered math models should include supporting data that validates the assumptions used within the model. State of the Art and Critical Gaps: These focus areas strive to reduce mass, volume, and power of a thermal control system in the next generation of robotic and human-class spacecraft and to enable long-term missions to the Moon and Mars. These improvements may come through either novel hardware solutions or modernization of software tools. The current state of the art in thermal control systems is vehicle power and mass impact of greater than 25 to 30% due to old technologies still in use. Furthermore, as missions become more variable (dormancy, environments, etc.), the need for intelligent design and control (both actively and passively) within the thermal control system becomes more apparent. For topology optimization (TO) in particular, it has become a well-established structural design tool, but it has yet to penetrate the thermal design community. Multiple research efforts have shown that TO of thermal-fluid systems is possible and can be successfully implemented to obtain optimized designs; however, a robust commercial code that can do this is yet to be demonstrated. Additionally, science payloads will continue to decrease in size, increase in power, and require precise temperature control, all of which cannot be readily provided by traditional thermal control methods due to vehicle-level impacts of overall performance, mass/volume, and power. Relevance / Science Traceability: Long-duration habitats (Moon, Mars, etc.). Lunar surface power. Mars transit vehicles. SmallSats/CubeSats. Rovers and surface mobility. Nuclear electric propulsion (NEP) systems. References: Stephan, R. "Overview of the Altair Lunar Lander Thermal Control System Design and the Impacts of Global Access," AIAA 2011-5001, 2011. Ewert, M. K. "Investigation of Lunar Base Thermal Control System Options," SAE Transactions, J. of Aerospace, 102(1), 829-840, 1993. Leimkuehler, T. O., et al. Operational Experience with the Internal Thermal Control System Dual-Membrane Gas Trap, 33rd International Conference on Environmental Systems (ICES), Vancouver, British Columbia, Canada, July 2003. Leimkuehler, T. O., et al. Effects of Surfactant Contamination on the Next Generation Gas Trap for the ISS Next Generation Gas Trap for the ISS Internal Thermal Control System, 34th International Conference on Environmental Systems (ICES), Colorado Springs, CO, July 2004. Wetch, J. R., et al. Megawatt Class Nuclear Space Power Systems (MCNSPS) Conceptual Design and Evaluation Report, Volumes I-IV, NASA CR-179614, September 1988. General Atomics Project 3450. Thermionic Fuel Element Performance Final Test Report, TFE Verification Program, GA-A21596 (UC-224), Prepared under Contract DE-AC03-86SF16298, Department of Energy, 1994. Ashcroft, J., and Eshelman, C. Summary of NR Program Prometheus Efforts, LM-05K188, 2006. Aerojet, SNAP-8 Performance Potential Study, Final Report, NASA CR-72254, 1967. Horner-Richardson, K., et al. Fabrication and Testing of Thermionic Heat Pipe Modules for Space Nuclear Power Systems, 27th IECEC, San Diego, CA, Paper Number 929075, 1992. Ernst, D. M., and Eastman, G. Y. High Temperature Heat Pipe Technology at Thermacore An Overview, AIAA-85-0981, 1985. Voss, S. S., and Rodriguez, E. A. Russian System Test Program (1970-1989), American Institute of Physics Conference Paper 94-0101, 1994. Stone, J. R. Alkali Metal Rankine Cycle Boiler Technology Challenges and Some Potential Solutions for Space Nuclear Power and Propulsion Applications, NASA Technical Memorandum 106593, July 1994. Demuth, S. F. SP 100 Space Reactor Design, Progress in Nuclear Energy, Volume 42, Number 3, 2003. Ashcroft, J. and Eshelman, C. Summary of NR Program Prometheus Efforts, LM-05K188, 2006. Davis, J. E. Design and Fabrication of the Brayton Rotating Unit, NASA CR-1870, March 1972. Richardson-Hartenstein, K., et al. Fabrication and Testing of Thermionic Heat Pipe Modules for Space Nuclear Power Systems, 27th IECEC, Paper Number 929075, 1992. Watkins, Ryan. "Designing Optical Instruments for Space Applications: Multiphysics Topology Optimization," 2019. Watkins, Ryan. "Topology Optimization: A Shift Towards Computational Design," 2016. Kambampati, Sandilya, and Hyunsun A. Kim. "Level Set Topology Optimization of Load Carrying Heat Dissipation Devices," AIAA Aviation 2019 Forum, 2019. Kambampati, Sandilya, and H. Alicia Kim. "Level Set Topology Optimization of Cooling Channels Using the Darcy Flow Model," Structural and Multidisciplinary Optimization (2020): 1-17. Feppon, Florian, et al. "Topology Optimization of Thermal Fluid Structure Systems Using Body-Fitted Meshes and Parallel Computing," Journal of Computational Physics 417 (2020): 109574.
