Combined cycle-coupled high-temperature and very high-temperature gas-cooled reactors: Part I-Cycle optimization

Very high-temperature gas-cooled reactors (VHTRs) have attracted worldwide attention because of their multiple uses, which include hydrogen production and high-efficiency power generation. Efficient power conversion is a key to improving the competitiveness of VHTRs. The combined cycle is a cyclic form of energy cascade utilization that makes full use of the high-temperature heat source of VHTRs. In this paper, a theoretical optimization method of combined-cycle efficiency is proposed for combined cycle-coupled high-temperature gas-cooled reactors (HTGRs) and VHTRs without considering specific engineering constraints. Based on a total differential analysis combined with a numerical analysis, the multi-variable combined-cycle efficiency was reduced to a function of two key parameters: the reactor outlet temperature and the main steam pressure. The remaining parameters can be determined by optimization within the defined domain. The theoretical optimization method proposed in this paper is conceptually clear and solves the problems presented by the many variables involved in combined cycle-coupled HTGRs without a clear variable optimization strategy. The results of this study provide guidance for the theoretical analysis and parameter design of combined cycle-coupled VHTRs. (C) 2019 Elsevier Ltd. All rights reserved.