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Moving Boundary Models for Dynamic Simulations of Two-Phase Flows

Munch Jensen, Jakob and Tummescheit, Hubertus LU (2002) In Modelica'2002 Proceedings p.235-244
Abstract
Two-phase flows are commonly found incomponents in energy systems such as evaporators and boilers. Theperformance of these components depends among others on thecontroller. Transient models describing the evaporation process areimportant tools for determining control parameters, and fast loworder models are needed for this purpose. This article describes ageneral moving boundary (MB) model for modeling of two-phase flows.The new model is numerically fast compared to discretized modelsand very robust to sudden changes in the boundary conditions. Themodel is a $7^th$ order model (7 state variables), which is asuitable order for control design. The model is also well suitedfor open loop simulations for systems design and optimization.It is... (More)
Two-phase flows are commonly found incomponents in energy systems such as evaporators and boilers. Theperformance of these components depends among others on thecontroller. Transient models describing the evaporation process areimportant tools for determining control parameters, and fast loworder models are needed for this purpose. This article describes ageneral moving boundary (MB) model for modeling of two-phase flows.The new model is numerically fast compared to discretized modelsand very robust to sudden changes in the boundary conditions. Themodel is a $7^th$ order model (7 state variables), which is asuitable order for control design. The model is also well suitedfor open loop simulations for systems design and optimization.It is shown that the average void fraction has a significant influenceon the system response. A new method to calculate the average voidfraction including the influence of the slip ratio is given. Theaverage void fraction is calculated as a symbolic solution to theintegral of the liquid fraction profile. (Less)
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published
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in
Modelica'2002 Proceedings
pages
235 - 244
publisher
Modelica Association
language
English
LU publication?
yes
id
6936b47e-6487-489a-9b20-ae4e87df8d4e (old id 537723)
alternative location
http://www.modelica.org/events/Conference2002/papers/p31_Jensen.pdf
date added to LUP
2007-09-24 09:04:18
date last changed
2016-04-16 08:32:27
@inproceedings{6936b47e-6487-489a-9b20-ae4e87df8d4e,
  abstract     = {Two-phase flows are commonly found incomponents in energy systems such as evaporators and boilers. Theperformance of these components depends among others on thecontroller. Transient models describing the evaporation process areimportant tools for determining control parameters, and fast loworder models are needed for this purpose. This article describes ageneral moving boundary (MB) model for modeling of two-phase flows.The new model is numerically fast compared to discretized modelsand very robust to sudden changes in the boundary conditions. Themodel is a $7^th$ order model (7 state variables), which is asuitable order for control design. The model is also well suitedfor open loop simulations for systems design and optimization.It is shown that the average void fraction has a significant influenceon the system response. A new method to calculate the average voidfraction including the influence of the slip ratio is given. Theaverage void fraction is calculated as a symbolic solution to theintegral of the liquid fraction profile.},
  author       = {Munch Jensen, Jakob and Tummescheit, Hubertus},
  booktitle    = {Modelica'2002 Proceedings},
  language     = {eng},
  pages        = {235--244},
  publisher    = {Modelica Association},
  title        = {Moving Boundary Models for Dynamic Simulations of Two-Phase Flows},
  year         = {2002},
}