Development and Application of an Open-Source Framework for Automated Thermal Network Generation and Simulations in Modelica

Abstract

District heating and cooling (DHC) networks, and in particular, the fifth generation of DHC networks, offer great potential in increasing the overall system efficiency and reducing CO2 emissions in the heating and cooling of urban districts. Due to the growing complexity of these energy systems, the use of new planning methods, such as the use of dynamic simulation models based on Modelica, becomes more important. However, especially with large, complex thermal networks, there is a high effort for manual model construction and parameterization. For this reason, we present a framework for automated model generation of DHC networks based on simulation models in Modelica written in Python. The core function of the Python framework is to transform a graph representation of a district heating network into a dynamic simulation model. The authors briefly describe the workflow and demonstrate its applicability with three different use cases. We investigate the impact of different design decisions, e.g., comparing the difference between central and decentral pumps as well as a combination of both in one network. In addition, we present the results of evaluating the impact of different network temperature levels or pipe insulation compared to the overall energy supplied to the network, leading to the conclusion that the presented framework is capable of reducing the manual effort for performing DHC network simulations with Modelicaand allows to easily perform parameter studies in an early planning phases in the future.

How to develop fifth-generation district heating and cooling in Sweden? Application review and best practices proposed by middle agents

“…The middle agents recommend the use of Modelica language for modeling 5GDHC systems since it offers features, including, but not limited to (i) multi-domain modeling covering thermal, fluid, control, and economic domains, (ii) hierarchical modeling from small components up to the assembly of large district systems, (iii) ability to model bidirectional mass flows, (iv) ability to reuse and/or edit existing component models (object-orientation), (v) acausal modeling where no strict definition of input/output relationships is required, (vi) easy adoption of design changes since the system architecture is retained. Such recommended use of Modelica as a physics-based modeling and dynamic simulation approach for 5GDHC systems confirms the latest findings in the literature (Abugabbara et al, 2020Abugabbara, 2021;Mans et al, 2022).…”

Planning the Design and Operation of Urban Energy Systems with Limited Data Availability: A Holistic Open-Source Tool Chain

“…For example, the district heating class sizes the hydraulic network based on a design pressure loss per pipe meter. Currently, uesgraphs includes three integrated system models: district heating, district cooling, and bidirectional models [10]. However, the framework is open to incorporating other network types.…”

“…In the last few years, numerous developments have been made to the models used; these address the extension of the optimization models [11] and the further development of substations for cold heating networks [10], as well as possibilities to calibrate the TEASER models with measurement data [4]. Besides the continuous improvements of the tools back-ends, the current major objective is to bring the tool chain from the planning phase into the operation phase of urban energy systems.…”