Simultaneous design and off-design operation optimization of a waste heat-driven organic Rankine cycle using a multi-period mathematical programming method

Abstract

The organic Rankine cycle (ORC) has been regarded as one of the most potential technologies for converting low-grade heat into power. In the past decades, the design and operation optimization of ORC has undergone investigation, and most approaches use a sequential or step-by-step approach by separating the off-design operation from the system design and typically lose solution optimality. The current study proposes a simultaneous optimization of the design and off-design operation for a waste heat-driven ORC. The detailed component configuration models for the heat exchangers are developed. A multi-period optimization model is developed to synchronously obtain the configurations of components and scheme of off-design operation that minimizes the annual average electricity production cost. A case study validates the superiority of the proposed multi-period optimization method over a two-step optimization. The ORC obtained using multi-period simultaneous optimization method features 5.7%–16.6% lower average electricity production cost than those achieved with the conventional two-step method.