OpenModelica-based modelling and simulation of a laboratory-scale district heating system

The goal of this thesis is to model a laboratory-scale district heating system to help test its performance and simulate diJerent scenarios and configurations. The experimental system in question is located inside the Politecnico di Torino laboratories and it was built to replicate in a smaller scale the characteristic behaviour of a district heating system. Heat generation is accomplished with a natural gas water heater. The primary circuit is composed of a small network of steel pipes which distributes hot water to two secondary circuits. Each of the two secondary circuits features a substation, composed of a plate heat exchanger and a circulation pump, and an air heater to simulate heat load. A thermal energy storage system is also present in one of the two secondary circuits. The aim of this work is creating a “digital twin” of this system, coupling each component present in the real setup with a digital one, trying to preserve their specific characteristics and features in the most accurate way possible. The foundation is OpenModelica software, an open-source Modelica-based modelling, compilation, and simulation environment, which enables the study of complex multi-domain physics systems. The core of this project is proving the feasibility of digital twin modelling using open-source software, highlighting the eventual advantages and weak points of this method. A step-by-step explanation is provided, including the construction of this model using mostly Buildings and Modelica Standard Library components, commenting on their implementation and behaviour inside the model itself, while mentioning the problems encountered and their relative fixes. Finally, the results of diJerent simulations are showcased including a default system configuration and a few other ones, such as one setup that includes the sensible thermal energy storage, or one with diJerent operational parameters, such as temperatures and mass flow rates.