Supercritical carbon dioxide(S-CO_2) power generation technology is considered as one of the most promising technologies for future coal-fired power generation due to its high efficiency and compact equipment. In view of the lack of research on global design and multi criteria evaluation of small capacity S-CO_2 cycle system components

this paper proposes a simultaneous system structural design-flow and heat transfer calculation-multi index evaluation computation method

and through calculation

it analyses the thermal economic performance of 50 MW S-CO_2 coal-fired power plant with different cycle systems and design parameters. The results show that

with the turbine inlet parameter of 25 MPa/620 ℃

the power generation efficiency of the recompression reheat cycle coal-fired power plant is 3.29% higher than that of the recompression cycle

and the levelized cost of electricity of the turbine is 2.52% lower than that of the recompression cycle. At different design parameters

the total investment cost of the two systems is both below 3.9×10~8 yuan

and the boiler cost accounts for about 80% of the total equipment investment cost.