Modeling of Solar District Heating: A Comparison Between TRNSYS and MODELICA
Abstract
In order to optimize their design, operation and control strategies, Solar District Heating (SDH) require thermalhydraulics simulations capabilities. In this paper, we present how SDH components and system models can be build both with the TRNSYS energy simulation program and the equation-based MODELICA simulation language. Therefore, three SDH components (pipe, substation and solar collector), a production plant and a recently built SDH network are modeled and simulated using TRNSYS and the Modelica/Dymola tool. The simulations performed show that both approaches yield similar results when comparable modeling details are considered in the software. However, the Modelica language has native multi-physics simulation capabilities. For instance, robust and publicly available solutions exist to account for hydraulics phenomena with the Modelica solution. On the other hand, extending the simulation scope of TRNYS to include hydraulics would be a very time-consuming task. On a general basis, it can be said that development costs are lower and modeling possibilities are wider for the Modelica solution. This overbalances the generally higher computational cost observed with the Modelica/Dymola solution. These reasons have led our research group to select the Modelica/Dymola tool to supplement the traditional solution based on TRNSYS for simulation activities related to SDH.