**ABSTRACT**

Mars is the target of deep space exploration. The first problem of landing on Mars and building a satellite base is the energy source. For more than 50 kW high power demand, space nuclear energy system has the advantages of high output power, large energy density, small area, short working time and so on. Super-critical CO2 Brayton cycle with sodium cooled fast reactor is the most promising power solution because of the high energy conversion efficiency. The thermodynamic model of super-critical CO2 Brayton cycle system with sodium cooled fast reactor as the heat source has been established. After the analysis of circulation process, the relationship between temperature, pressure and enthalpy at working point has been discussed, and the relationship of circulation efficiency has been deduced. The real gas model is used to correct the thermophysical properties of super-critical CO2. The thermal efficiency of the system is analyzed under the typical working condition of Mars surface. What's more, the effects of pressure ratio, compressor inlet temperature, turbine inlet temperature, and the temperature ratio on the cycle efficiency are discussed to get the optimal cycle characteristic and condition parameters.

**KEYWORDS**

PAPER SUBMITTED: 2021-04-19

PAPER REVISED: 2021-06-18

PAPER ACCEPTED: 2021-07-10

PUBLISHED ONLINE: 2021-12-24

**THERMAL SCIENCE** YEAR

**2021**, VOLUME

**25**, ISSUE

**Issue 6**, PAGES [4659 - 4666]

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