A new theoretical model of steady-state characteristics of supercritical carbon dioxide natural circulation

Due to its commendable thermal properties in the supercritical region, supercritical carbon dioxide shows great promise as the working fluid of the Brayton cycle, which could achieve remarkable higher efficiency compared with steam Rankine cycle. The steady-state characteristics are essential for the design of supercritical carbon dioxide power conversion system. In the present article, the steady-state characteristics of supercritical carbon dioxide natural circulation were theoretically and experimentally studied. An one-dimensional theoretical model of steady-state characteristics of supercritical carbon dioxide natural circulation was put forward, which was developed in an analytical form. So far as is known to the authors, no similar theoretical model has been carried out ever. Experiments on the steadystate characteristics of supercritical carbon dioxide natural circulation were performed. The influence of system pressure, inlet temperature and enthalpy difference on the steady-state characteristics was discussed in detail. Results indicated that the steady-state characteristics of supercritical carbon dioxide natural circulation were closely related to geometrical parameters as well as thermal properties at the pseudo-critical point. The new theoretical model was further validated with present experimental data and available experimental results from the open literature. (C) 2019 Elsevier Ltd. All rights reserved.