Bachelor's thesis Thomas Dixius

 

Modelling and Simulation of a Heat Transfer Station for District Heating Grids

In order to make existing and future district heating networks more efficiently and to contribute
to a sustainable energy supply, it is useful to simulate the district heating networks. In contrast
to the common approaches that simplify the systems, the E.ON Energy Research Center in Aachen
choosed another way. This alternative approach is characterised by a more detailed model of a district
heating network and should give more detailed information on the grid behavior. Therefore,
in this thesis a real district heating substation wasmodeled. The used programming language was
Modelica and the used graphical development environment was Dymola. The goal was to develop
a model that uses the variables of the primary flow and the secondary return to determine the primary
return and the secondary flow. Thereby, greater emphasis was attached to the primary circuit
as this has a greater influence on the behavior of the district heating network. In order to develop
a model with these requirements, sub-models for the plate heat exchanger, the temperature regulation
and the differential pressure regulators were developed. A comparison of the simulation
results has shown a high correlation between simulated and measured values. In contrast to the
simulated temperatures, the simulated primary mass flow has a non-negligible deviation fromthe
real values. However, the deviation of the simulatedmass flow is partially caused by measurement
errors in the input data. Therefore it can be assumed that more accurate input variables provide
better simulation results. Finally the analysis of simulation results has shown that the developed
model is stable and provides plausible results.