Modelling and optimization of an industrial plant using Modelica

Abstract

This thesis provides an insight into the design of industrial plants in order to achieve energy efficiency. Improvements in their models enable sustainable development and energy savings. For the evaluation of possible energetic optimizations, a new design concept is necessary. Therefore, the energy supply of an industrial plant is analysed. This plant consists of refrigeration systems which heat at temperatures around 100 ºC and provide coldness around -20 ºC. The installation of thermal energy storages (TES) to store and cover energy peaks point out the development of different scenarios and the possible areas of evaluation. In addition, the components which ensure refrigeration and provide the required heat to other processes are industrial heat pumps (HP). In order to use the waste heat produced, another HP can be combined in series. Their combination is expressed as a cascade HP. The modelling and simulation of two complete dynamic models (Model A and Model B) were developed accordingly using OpenModelica: • Model A: Coldness for a deep-freeze room and usage of the waste heat • Model B: Heating and fast cooling of the final products The modelling building strategy is defined with blocks of components. This adaption was required to avoid numerical issues and the difficulties to build large models with Modelica software. However, it has its own benefits as offers the possibility to test each component independently. Small design modifications enable the execution of different applications. Results evidence the robustness and reliability of the models. The ideal thermodynamic cycle represents the efficiency of the HPs at different operating conditions with COP efficiencies around 3. The charging and discharging process of the TES is regulated with a sophisticated control system. Every TES show a vertical stratification of temperatures defined by fluid layers. Both processes operate at different power consumption values over time. The possibility to reuse Modelica elements opens a wide range of opportunities for future development. This work is a starting proposal for the modelling of different industrial plants and aims to contribute to new research perspectives. Overall, further exergy analysis can be carried out to evaluate the performance of the process.