Analysis of steam storage systems using Modelica

Abstract

Industrial process heat applications have been identified as a promising new area of application for thermal energy storage systems. Storage systems offer not only the reuse of thermal energy in cyclic processes which facilitates the integration of solar energy due to the availability of storage capacity. The bulk of process heat applications require steam at pressures between 1 and 20. While the application of phase change materials (PCMs) is straightforward for isothermal energy storage, no commercial system is available in this temperature range today. Modelica is used to analyse different kinds of steam storage systems for applications in power plants and process industry. The analysis includes varying pressure steam accumulators, which are state of the art, and a novel kind of steam accumulator with a phase change material (PCM). For the analysis of steam accumulators a vertical discretisation of the storage vessel is elemental. Based on the Fluid and Media Library models for the simulation of multiphase flows are developed. The drainage and flooding of volumes can be reproduced as well as the vertical stacking. Based on the media library a general multiphase media package is build for the handling of multiphase applications.