Optimal design of an organic Rankine cycle system considering the expected variations on heat sources

Abstract

This paper addresses the optimal design of an organic Rankine cycle (ORC) system with consideration of the expected variations on heat sources in multi-product plants and multi-period operation processes. For a series of the given heat sources with variable numbers and temperatures, a two-step method was proposed to reach the maximum thermal efficiency and to reduce the investment cost of the system as much as possible. In the first step, a multi-period optimization model that contains a rigorous thermodynamic sub-model is developed to determine the optimal configuration of ORC system, including the optimal working fluid and the corresponding operating parameters of an ORC system. In the second step, the heat recovery network connecting the heat sources and the ORC system is optimized to minimize the investment cost of the integrated system through a multi-period time-sharing mechanism. The effects of the heat source variations on the selection of working fluid, the performance and economy of ORC system are thus analyzed. The effectiveness and application of the proposed method are finally verified via a case study of a keto-benzene dewaxing process.