Energy conversion system optimization study for multimegawatt space nuclear power applications

A detailed description of the energy conversion system analysis and optimization procedures are presented that were part of a broader preliminary study aimed at designing a multimegawatt (MMW) space nuclear power system. In optimizing the energy conversion system it is assumed that the most-massive component of the system is the radiator, and therefore the subject of optimization is the radiator mass. The closed-loop Brayton and the liquid-metal Rankine cycles are analyzed for a 165-MWe system. The radiator-mass-optimized systems based on both cycles are compared for a wide range of operating conditions. For a 165-MWe power output, the MMW power system mass is calculated using an open-loop Brayton cycle. For the desired electric power output, results show that the hydrogen-cooled/potassium Rankine cycle is the recommended energy conversion system since it is superior to any closed-loop Brayton cycle. Results also show that the open-loop Brayton cycle system with a hydrogen working fluid has mass comparable to the selected Rankine cycle system