Design and Simulation Model of Medium Scale Organic Rankine Cycles - Validation on Waste Heat Recovery Plant and Case Studies

Abstract

The document is divided in two parts. The first one proposes an ORC model developed at (and for) Enertime SA, a French company that sells medium scale ORC machines and engineering services. This model, developed in Python 3.4, is able to cover a wide range of medium to large scale machines, and to answer to simulation and design problems. It is designed to be as general as possible, but with sufficient accuracy and the opportunity for easy further development. The first part of the report is thus dedicated to the description of the model and its implementation.

In a second part, the model is confronted to two case studies. The first one is a waste heat recovery ORC of 3 MW based in China. Measurements were retrieved from effective operating points to analyze and validate the accuracy of the model. The second one focuses on a specific application of the model in order to illustrate the potential of it. The model is there used to answer to a specific industrial problem related to the design and the control of an air-condenser in a geothermal ORC application.

The model presented in this paper is able to design and simulate medium to large scale Organic Rankine Cycles (ORC) with shell and tubes heat exchangers in different configurations with good robustness. It allows to add a recuperator and/or a preheater in parallel or in series. The Moving Boundary Model that has been implemented allows to simulate almost all temperature profiles. Some simulation equations that have been used were simplified in order to obtain a user-friendly tool that does not require too much upstream research or information to get acceptable results. Of course, this implies a limited accuracy. Still, it is shown that model provides rather good order of magnitude, considering the apparent simplicity of some constituting equations.