Simulation eines Parabolrinnenkollektors mit direkter Dampferzeugung

Kurzfassung

Simulation of a Parabolic Trough Collector with Direct Steam Generation In this diploma thesis, a model library for the simulation of a parabolic trough collector with direct steam generation in the absorber tubes is created. The model library is written in Modelica, a unified object-oriented language for physical systems modelling. The translation of the Modelica-code into C-code is performed by the simulation programme Dymola. The modelling of the two-phase flow is done under the assumption of a homogenous equilibrium model. By means of the theory of characteristics the underlying partial differential equations of flow are simplified and the changed properties of the resulting, simplified equations are examined. The used models for the phase distribution, the heat transfer and the pressure drop are presented. Different finite difference schemes for the discretization of the conservation equations of fluid flow are investigated and their properties are explained theoretically. The validation of the collector model is done by means of an already existing, validated model and by comparison with measurements of a test facility. Some simulations are performed for examining the dynamic behaviour of a single collector of the evaporator and superheater section after a step change in irradiation, inlet mass flow, inlet specific enthalpy and injection mass flow. One simulation study investigates the part of the collector which contains the preheater and evaporating section. In the last chapter, a simulation of the superheater section of a test-facility for direct steam generation with real boundary conditions is presented. The performed simulations should be considered as exemplary and not as a detailed study of the dynamics of a solar steam generating system. The focus of this thesis is on the creation of the model library.