Master's Thesis Jiewei Liu


Generalization and Extension of a Simulation Model of an Air Handling Unit

AHU_model Copyright: EBC Schematic representation of an AHU model

To determine the energy demand of buildings, a simulation model of an air handling unit is usually implemented. Because the energy demand of an air handling unit makes up a large proportion of the total energy consumption of the building. An existing model of an air handling unit is used to simulate the important energetic behaviour of real systems within a short time. In order to improve and generalize the existing model, a generic simulation model of an air handling unit is implemented in this thesis. For this purpose, reusable component models of air handling units are modelled in the Modelica in a general way, so that they can be used for different types of air handling units. The modular model is parametrized according to requirements and is used to calculate the energy demand of an air handling unit.

Furthermore, the simulation model is validated by using experimental measurement data from a test rig. These experiments are under various operating states heating, cooling and dehumidifying performed. The deviations between measured and simulated results are evaluated and the assumption in the modelling is analysed.

Additionally, three comparisons with different simulation models of an air handling unit are carried out. A comparison with AHU-Model in the AixLib is used to check the functionality of the model, and a good match of both models is achieved. Subsequently, a comparison with a complex model is made with the aim of analysing the computational effort, thus the simplified model achieves an excellent simulation time saving compared to the complex model. In a last step, the model is compared to a Python model to discuss the differences between simulation software. The simulated energy consumption also achieve a good agreement, the quality of this congruency is expressed by the coefficient of determination.