https://orcid.org/0000-0002-0689-3546
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Abstract
Heat rejection radiators of nuclear reactor power systems for space exploration and for planetary surface power are the largest component by volume and mass, depending on the radiator’s design and surface average temperature. This work developed designs for lightweight radiator modules for waste heat rejection on the lunar surface at a surface average temperature of 600 K. The modules each have a cesium (Cs)–titanium (Ti) heat pipe (HP) and highly oriented pyrolytic graphite (HOPG)/Ti heat spreading fins. The assembled panels of 10 Cs-HP modules hydraulically coupled in parallel are armored with carbon-carbon composite to protect against impacts by micrometeoroids and space debris for 10 years. The performance of the developed armored radiator panels is much superior to the current state of the art, with an areal density of 2.98 to 3.6 kg/m2, specific power of 3.36 to 3.98 kW/kg, rejected thermal power of 56.3 to 96.3 kW, and rejected power density of 7.56 kW/m2.
Acronyms
| AFSPS: | = | affordable fission surface power system |
| AMTEC: | = | alkali metal thermal to electric conversion |
| C-C: | = | carbon-carbon [composite] |
| CBC: | = | closed Brayton cycle [energy conversion] |
| CFD: | = | computational fluid dynamics |
| Cs: | = | cesium |
| EOL: | = | end of life |
| FOM: | = | figure of merit |
| FPSE: | = | free piston Stirling engine |
| FSPS: | = | fission surface power system |
| He: | = | helium |
| HOPG: | = | highly oriented pyrolytic graphite |
| HP: | = | heat pipe |
| HPTrAMTM: | = | Heat Pipe Transient Analysis Model |
| HP-STMCs: | = | heat pipe-segmented thermoelectric module converters |
| JIMO : | = | Jupiter Icy Moons Orbiter |
| Li: | = | lithium |
| L-V: | = | liquid-vapor [interface] |
| Mo: | = | molybdenum |
| Na: | = | sodium |
| NaK-78: | = | sodium-potassium eutectic (sodium-potassium alloy with 78 wt% potassium) |
| NASA: | = | National Aeronautics and Space Admini-stration |
| RANS: | = | Reynolds-averaged Navier-Stokes |
| Rb: | = | rubidium |
| SAIRS: | = | Scalable AMTEC Integrated Reactor space power System |
| SCoRe-TE: | = | Sectored Compact Reactor with TE [conversion for lunar surface power system] |
| SiGe: | = | silicon-germanium |
| SOA: | = | state of the art |
| SST: | = | Shear Stress Transport |
| TE: | = | thermoelectric [energy conversion] |
| TI: | = | thermionic [conversion] |
| Ti: | = | titanium |
| UNM-ISNPS: | = | The University of New Mexico Institute for Space and Nuclear Power Studies |
| Ver(s).: | = | version(s) |
| Xe: | = | xenon |
| 2-D: | = | two-dimensional |
| 3-D: | = | three-dimensional |
Nomenclature
| Avap = | = | heat pipe vapor flow area (m2) |
| DHP = | = | heat pipe curvature diameter (m) |
| Dh = | = | equivalent hydraulic diameter (m) |
| hfg = | = | latent heat of vaporization (kJ/kg) |
| L = | = | length (m) |
| Lcd = | = | heat pipe condenser length (m) |
| Lev = | = | heat pipe evaporator length (m) |
| Lhp = | = | heat pipe total length (m) |
| ṁ = | = | liquid NaK-78 flow rate (kg/s) |
| MW = | = | molecular weight of working fluid (kg/mol) |
| Prt = | = | turbulent Prandtl number |
| Rg = | = | gas constant (J/mol∙K) |
| Rp = | = | geometric radius of pores in sintered wick in heat pipe (m) |
| Q = | = | heat pipe power throughput (W) |
| Qent = | = | heat pipe entrainment limit (W) |
| T = | = | temperature (K) |
| Tex = | = | circulating liquid NaK-78 exit temperature (K) |
| Tev = | = | heat pipe evaporator temperature (K) |
| Tin = | = | circulating liquid NaK-78 inlet temperature (K) |
| Ts = | = | radiator surface average temperature for heat rejection (K) |
| Wfin = | = | width of the HOPG/Ti heat spreading fins (cm) |
| Greek | = | |
| ΔPcap = | = | heat pipe capillary pressure head (Pa) |
| ΔPl = | = | liquid pressure losses (Pa) |
| ΔPv = | = | vapor pressure losses (Pa) |
| ε = | = | radiator surface emissivity |
| μl = | = | liquid viscosity (Pa∙s) |
| ρv = | = | vapor density (kg/m3) |
| σl = | = | liquid surface tension (N/m) |
Acknowledgments
NASA funded this work, under grant number 80NSSC22K0263 to UNM-ISNPS. We are grateful for the access to the resources of the High-Performance Computing Center at Idaho National Laboratory, supported by the Office of Nuclear Energy of the U.S. Department of Energy and the Nuclear Science User Facilities under contract number DE-AC07-05ID14517, and at The University of New Mexico Center for Advanced Research Computing, supported in part by the National Science Foundation, for providing access to its high-performance computing capabilities.
Disclosure Statement
No potential conflict of interest was reported by the author(s).