Carbon Dioxide Power Systems: Research Lines at Initial Design Stages and Application Prospects in Russia

Carbon dioxide power systems (СО₂-PS) are thermal power facilities in which carbon dioxide (СО₂) is used as a working fluid. Given a fairly high initial temperature upstream of the turbine, their efficiency may be higher than that of steam turbine analogs. In all developed countries, intense studies aimed at development of СО₂-PSs for various purposes are carried out, as a rule, with active participation of the state sector, including the development of state programs and addressed budgetary financial support, with the majority of R&D works carried out in the capacity of national laboratories and research institutes, with planning the works and monitoring their progress. Special attention is paid to solving the problem of decreasing the metal intensity and cost of heat-transfer equipment. It is shown—taking as an example a feasibility study of modifying the domestically developed 1200 MW sodium-cooled fast nuclear power facility by replacing the steam power plant by a СО₂-PS—that such modification for large capacity power plants with moderate initial temperature levels results in degraded economic efficiency as a consequence of much higher metal intensity, larger overall dimensions, and cost of the heat-transfer equipment. Better economic efficiency in comparison with similar steam turbine plants can be achieved by increasing the initial temperature and decreasing the capacity of a single power unit. At the initial design stages, it is advisable to place the focus on developing a small capacity power part equipment of one standard size (with a standardized main compressor) intended for being used in СО₂-PS at solar, nuclear, and thermal power facilities. The development of an experimental demonstration (ED) small-capacity СО₂-PS intended for carrying out tests and experimentally perfecting the equipment and technology of its operation is a mandatory stage in the development of СО₂-PSs for different capacities and purposes. For decreasing the cost of ED СО₂-PS recuperators, it is necessary to construct a bench for testing the heat-transfer modules (HTMs) of which the СО₂-PS recuperators will be assembled. A basic thermal cycle circuit of the bench facility that will accurately replicate the operation conditions of HTMs as part of the ED СО₂-PS recuperators is developed. The tasks that have to be solved based on the experimental study results are described, and examples of the schematic diagrams of microchannel heat exchangers using which the HTMs can be made more compact are given. Detailed design documents for HTM equipment shall be developed in coordination with the development of technological documentation and plans for improving the technological preparation of manufacture at the industrial partner enterprise that will undertake the task of producing the ED СО₂-PS heat-transfer equipment.