Multiobjective Optimization Method for an Organic Rankine Cycle Integrated with the Heat Exchanger Network

Abstract

This paper presents a multiobjective mixed-integer nonlinear programming (MOMINLP) model to handle the trade-off issue between improving the heat recovery quantity and quality as well as considering economic feasibility in the integration of an organic Rankine cycle (ORC) with the heat exchanger network (HEN). The first objective is the minimum utility consumption (Quc) of the stand-alone HEN, after which ORC is constrained upon just absorbing heat below the pinch point of HEN. The second objective is the minimum equivalent thermal resistance (Rex), which represents the higher heat recovery quantity and quality of the HEN–ORC integration. The third objective is the minimum total annual cost (TAC) to ensure economic feasibility. Finally, the optimum working fluid, operating conditions, and the optimum structure for the HEN–ORC integration are obtained. Moreover, a well-studied example is solved to highlight the benefits of the proposed method.