Comprehensive evaluation of integrated solar combined cycle system regarding fuel-savability under unified framework

Abstract

Integrated Solar Combined Cycle (ISCC) system is considered as a promising route to efficiently utilize both solar energy and fossil fuel. However, due to the absence of a unified framework, it is difficult to fairly compare the performance between numerous proposed integration schemes. In the present work, firstly, a generalized model of ISCC system is proposed with validation, based on which the unified expression of fuel-savability is derived for performance evaluations between different integration schemes under a common framework. Secondly, the “allocation effect” expressed by the “bridging” term of the unified expression is revealed that the proportion of total input exergy allocated to the Brayton and Rankine cycles varies due to the solar integration. Thirdly, the “superposition effect” is revealed that the total system fuel-savability is comprehensively determined by the superposed sum of the “basic” term, which is the direct benefit of local solar integration, the “floating” term, which stands for the explicit influence of solar integration on each main component, and the “bridging” term, which stands for the implicit inter-cycle influence of solar integration. Fourthly, six individual cases of ISCC schemes have been evaluated by the proposed unified expression as the example of practical application. Finally, the two above-mentioned effects have been further extended to be compatible with more complicated solar-integrated multicycle-combined system and the unified expression form of fuel-savability is rationally generalized, which may provide theoretical guidance for the future research and applications.