Heat current method for integrated analysis and optimization of thermodynamic systems

Abstract

Performance analysis and optimization of thermodynamic systems are important in increasing the efficiency of energy systems, but traditional approaches cannot meet the demand of high-efficiency performance analysis for complex thermodynamic systems. Based on the entransy theory, the recently developed heat current method, combined with the specialized simulation algorithm, offers a new and attractive solution for performance analysis of thermodynamic systems. This paper first presents the standardized heat current modeling strategy for thermodynamic systems, taking a Rankine cycle power generation system as an example to present the modeling procedure. Combining flow constraints and physical property constraints of working fluids, the framework of construction of a global system mathematical model is then presented. In the proposed framework, linear, nonlinear explicit, and nonlinear implicit system constraints can be separated. Consequently, the number of constraints needing to be solved iteratively is minimized. Based on this separation feature, this paper further proposes and presents a hierarchical and categorized algorithm that could reduce calculation time greatly and improve calculation stability significantly. Finally, a triple-pressure steam power generation system is investigated to demonstrate the advantages of the proposed hierarchical and categorized algorithm compared with conventional methods from the aspects of the time required for calculation and the initial values required.