ORC and sCO₂ cycle for high temperature WHR applications

Department of Power System Engineering, Faculty of Mechanical Engineering, University of West Bohemia in Pilsen, Univerzitni 22, 306 14, Pilsen, Czech Republic.

^* Corresponding author: tereza.kubikova@doosan.com

Abstract

This article suggests a suitable closed thermodynamic cycle for waste heat from a cement plant by using alternative working fluids. A pair of closed working cycles is compared: supercritical CO₂ cycle (sCO₂) and the Organic Rankine Cycle (ORC). In the case of ORC, it was necessary to choose a suitable working fluid. The goal is to minimize the ODP (Ozone Depletion Potential) and GWP (Global Warming Potential), to maximize the thermal efficiency and to optimize the minimum working temperature difference (pinch points, approach points), the temperature profiles of the heat exchangers and their working pressure and temperature, which affects the cost. Both cycles (ORC and sCO₂) including a detailed component analysis are calculated using Python in Spyder IDE, which includes all the libraries for this task. According to the results of the calculations, the ORC cycle was chosen for further calculations of the components (condenser and turbine). The most suitable working fluids with high efficiency are hexamethyldisiloxane (MM), ethylbenzene and toluene, from which toluene was selected.