.AixLib.Fluid.Storage.BufferStorage

Information

Overview

Buffer Storage Model with support for heating rod and two heating coils.

Concept

It represents a buffer storage stratified into n layers where 1 represents the bottom layer and n represents the top layer. The layers are connected to each other allowing heat and fluid transfer.The heat transfer between the layers can be selected to model the conductance between the layers or different models that additionally represent the buoyancy:

HeatTransferOnlyConduction: Model for heat transfer between buffer storage layers. Models conductance of water. An effective heat conductivity is therefore calculated. Used in BufferStorage model.

HeatTransferLambdaSimple: Model for heat transfer between buffer storage layers. Models conductance of water and additional effective conductivity (in case the above layer is colder than the lower layer). Used in BufferStorage model.

HeatTransferLambdaEff: Model for heat transfer between buffer storage layers. Models conductance of water and buoyancy according to Viskanta et al., 1997. An effective heat conductivity is therefore calculated. Used in BufferStorage model.

HeatTransferLambdaEffSmooth: Same as HeatTransfer_lambda_eff. In addition, the smooth() expression is used for the transition of the buoyancy model.

HeatTransferLambdaEffTanh: Same as HeatTransfer_lambda_eff. In addition, a tanh function is used for the transition of the buoyancy model (VariableTransition model). Attention: the initial value of the FullTransition model is 0.5. This may lead to a mixture of the storage at the beginning of the simulation.

HeatTransferBuoyancyWetter: Model for heat transfer between buffer storage layers. Models buoyancy according to Buildings.Fluid.Storage.BaseClasses.Buoyancy model of Buildings library, cf. https://simulationresearch.lbl.gov/modelica. No conduction is implemented apart from when buoyancy occurs.

The geometrical data for the storage is read by records in the DataBase package. The model also includes heat losses over the storage walls (wall, top and bottom). No pressure losses are included. Thus external pressure loss models are required for the use of the model.

Sources

• R. Viskanta, A. KaraIds: Interferometric observations of the temperature structure in water cooled or heated from above. Advances in Water Resources, volume 1, 1977, pages 57-69. Bibtex-Key [R.VISKANTA1977]

Example Results

AixLib.Fluid.Storage.Examples.BufferStorageCharging

Contents

Revisions

• November 27, 2019, by Philipp Mehrfeld:
  - #793
  - Replace MSL pipe by AixLib.Fluid.FixedResistances.PlugFlowPipe.
  - Add energyDynamics and tidy up with heat transfer models.
• October 12, 2016  by Marcus Fuchs:
  Add comments and fix documentation
• October 11, 2016  by Sebastian Stinner:
  Added to AixLib
• March 25, 2015  by Ana Constantin:
  Uses components from MSL
• December 10, 2013 by Kristian Huchtemann:
  Added documentation of storage and new heat transfer models.
• October 2, 2013  by Ole Odendahl:
  Added documentation and formatted appropriately
• February 19, 2013 by Sebastian Stinner:
  mistake in losses calculation corrected (thickness of "wall" and "insulation" was only considered once but has to be considered twice, additionally the components "wall" and "insulation" were exchanged )
  and mistake in bouyancy model "Wetter" corrected (bouyancy flows were flowing in the wrong direction)