Heat exchange networks (HENs) account for a large proportion of initial investment in process engineering. It is of great significance for energy recovery and cost saving to integrate organic Rankine cycles (ORCs) with HENs. However, the difficulty lies in how to get the optimum integration scheme. In the optimization, the organic working fluid and its operating parameters determine the performance of the ORC, and the system configuration scheme affects the heat transfer matching degree and economic performance. Therefore, they are all important variables that affect the energy utilization, irreversibility, and economy of the integrated system. It is necessary to optimize them simultaneously. In this paper, we take them as variables and propose a simultaneous optimization method for directly integrating an ORC with a HEN. The total exergy destruction (TED) and the total annual cost (TAC) are adopted as two objectives. To solve this complex multiobjective mixed integer nonlinear programming problem, a solving strategy based on ε constraint method is adopted. We first determine two anchor points for obtaining Pareto Frontier. Then, the TED of integrated systems is equally divided into several intervals between the anchor points. Finally, a set of Pareto optimality is obtained by solving a series of optimization problems with TAC as a single objective until the end conditions are met. Two case studies are analyzed, and the results show that the proposed optimization method can effectively reduce the TED and TAC.
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 (Q
uc) 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 (R
ex), 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.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.