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• Recent advances in supercritical carbon dioxide power system are summarized. • The general and unique problems in coupling of supercritical carbon dioxide power cycle and different heat sources are identified. • The multiscale features of supercritical carbon dioxide power system are demonstrated. • Applications of supercritical carbon dioxide power system in nuclear, solar energy and fossil fuel are discussed. • An outlook on technical challenges is presented to promote industrial applications. Under the background of carbon reduction, the development of efficient power conversion system has drawn more important attention. The advantages of high efficiency and compactness have triggered increasing industrial interests in the applications of supercritical carbon dioxide power system for broad heat sources. However, when the supercritical carbon dioxide power cycle is coupled with different heat sources, there exist both general problems mainly associated with the supercritical carbon dioxide cycles and unique problems due to the heating processes of supercritical carbon dioxide. Moreover, the multiscale features of the supercritical carbon dioxide power system lead to significant challenges to theoretical analysis and engineering design. This review work provides the recent advances of supercritical carbon dioxide power systems, especially for the applications in heat sources of nuclear, solar and fossil fuel. With a focus on the category of general problems and unique problems, the current studies concerning the coupling of supercritical carbon dioxide power cycle with a specific heat source are further divided into three scales of system, component and process. The designs of the reactor core in nuclear, the receiver in concentrated solar power plant and the boiler in coal-fired power plant are discussed in detail at the scales of system, component and process. Future research directions for supercritical carbon dioxide power system are identified at different scales and more accurate integrated modelling for the coupling of supercritical carbon dioxide power cycle with specific heat sources are encouraged. The present work will benefit the in-depth understanding and further promotion of supercritical carbon dioxide power systems in industrial applications. [ABSTRACT FROM AUTHOR]

• Integration and conversion of supercritical carbon dioxide coal-fired power cycle and high efficiency energy storage cycle are discussed. • A three-step strategy is proposed and various cycles are presented and assessed. • First step: the tri-compression coal-fired integrated energy storage cycle has a high efficiency. • Second step: the integrated energy storage cycle with various heat sources needs to consider the trade-off of performance criteria. • Third step: the high efficiency split expansion adiabatic energy storage cycle is proposed. The emission peak/carbon neutrality calls for significantly improved coal-fired power plants. Sustainability of the power plants is critical to meeting the net zero targets in 2050/2060. In this context, it is necessary to investigate the integration and conversion of the supercritical carbon dioxide coal-fired power cycle and the supercritical carbon dioxide energy storage cycle. In this work, the thermodynamic model and performance criteria are firstly presented. After comparison of the two cycles, a three-step strategy for the development of the power cycle is proposed and assessed. First step: when coal still plays an important role as a main energy resource, the integrated tri-compression coal-fired supercritical compressed carbon dioxide energy storage cycle has the highest round-trip efficiency of 56.37%. Second step: with the challenge in utilization of coal energy, a trade-off among the performance criteria must be struck in the integrated cycle with various heat sources. Third step: the adiabatic supercritical compressed carbon dioxide energy storage cycle is proposed, and a high round-trip efficiency of 72.34% is achieved in the split expansion cycle. The present research provides not only a new prospect of the conventional power plants but also design guidance for the supercritical carbon dioxide energy storage cycle. [ABSTRACT FROM AUTHOR]

The S–CO 2 Brayton cycle has been considered as a promising alternative in coal-fired power plants due to its high efficiency and high compactness. However, the high inlet temperature and low heat transfer coefficient of S–CO 2 in the cooling wall tubes arranged in the furnace could lead to thermal fragile in practical operation. In present study, thermal-hydraulic-structural evaluation on S–CO 2 cooling wall tubes is investigated. Firstly, it is found that the stress distribution is mainly dominated by the circumferential temperature gradient. Secondly, a new criterion, the thermal deviation factor (TDF), is proposed to evaluate the tube thermal stress. It indicates the plastic deformation if exceeding the critical value of TDF = 1, which is more efficient than conventional structural analysis. Thirdly, based on the TDF , two typical methods of inserting twisted tapes and unilaterally arranging dimples inside the tube are proposed to reduce the thermal stress. A novel configuration of elliptic dimple with rounded corners is finally proposed to reduce the local stress concentration efficiently. The results show that the elliptic dimples have the highest comprehensive performance, which is recommended as the heat transfer enhancement structures in S–CO 2 cooling wall tubes. • Thermal-hydraulic-structural performance of S–CO 2 cooling wall tube is investigated. • A new thermal deviation factor (TDF) is proposed to evaluate thermal stress. • Twisted tapes and unilaterally arranged dimples are used to reduce thermal stress. • A novel elliptic dimple can release local stress concentration and improve comprehensive performance. [ABSTRACT FROM AUTHOR]