Buildings.UsersGuide.ReleaseNotes

• Version 0.9.1 (June 24, 2010)
• Version 0.9.0 (June 11, 2010)
• Version 0.8.0 (February 6, 2010)
• Version 0.7.0 (September 29, 2009)
• Version 0.6.0 (May 15, 2009)
• Version 0.5.0 (February 19, 2009)
• Version 0.4.0 (October 31, 2008)
• Version 0.3.0 (September 30, 2008)
• Version 0.2.0 (June 17, 2008)
• Version 0.1.0 (May 27, 2008)

Package Content

Name	Description
Version_0_9_1	Version 0.9.1
Version_0_9_0	Version 0.9.0
Version_0_8_0	Version 0.8.0
Version_0_7_0	Version 0.7.0
Version_0_6_0	Version 0.6.0
Version_0_5_0	Version 0.5.0
Version_0_4_0	Version 0.4.0
Version_0_3_0	Version 0.3.0
Version_0_2_0	Version 0.2.0
Version_0_1_0	Version 0.1.0

Buildings.UsersGuide.ReleaseNotes.Version_0_9_1

Buildings.Fluid.Storage.

Buildings.Fluid.Storage.StratifiedEnhanced

The model Buildings.Fluid.Storage.BaseClasses.Stratifier had a sign error that lead to a wrong energy balance. The model that was affected by this error is Buildings.Fluid.Storage.StratifiedEnhanced. The model Buildings.Fluid.Storage.Stratified was not affected. The bug has been fixed by using the newly introduced model Buildings.Fluid.Storage.BaseClasses.ThirdOrderStratifier. This model uses a third-order upwind scheme to reduce the numerical dissipation instead of the correction term that was used in Buildings.Fluid.Storage.BaseClasses.Stratifier. The model Buildings.Fluid.Storage.BaseClasses.Stratifier has been removed since it also led to significant overshoot in temperatures when the stratification was pronounced.

Buildings.UsersGuide.ReleaseNotes.Version_0_9_0

• Added the following heat exchanger models
  • Buildings.Fluid.HeatExchangers.DryEffectivenessNTU for a sensible heat exchanger that uses the epsilon-NTU relations to compute the heat transfer.
  • Buildings.Fluid.HeatExchangers.DryCoilCounterFlow and Buildings.Fluid.HeatExchangers.WetCoilCounterFlow to model a coil without and with water vapor condensation. These models approximate the coil as a counterflow heat exchanger.
• Revised air damper Buildings.Fluid.Actuators.BaseClasses.exponentialDamper. The new implementation avoids warnings and leads to faster convergence since the solver does not attempt anymore to solve for a variable that needs to be strictly positive.
• Revised package Buildings.Fluid.Movers to allow zero flow for some pump or fan models. If the input to the model is the control signal y, then the flow is equal to zero if y=0. This change required rewriting the package to avoid division by the rotational speed.
• Revised package Buildings.HeatTransfer to include a model for a multi-layer construction, and to allow individual material layers to be computed steady-state or transient.
• In package Buildings.Fluid, changed models so that if the parameter dp_nominal is set to zero, then the pressure drop equation is removed. This allows, for example, to model a heating and a cooling coil in series, and lump there pressure drops into a single element, thereby reducing the dimension of the nonlinear system of equations.
• Added model Buildings.Controls.Continuous.LimPID, which is identical to Modelica.Blocks.Continuous.LimPID, except that it allows reverse control action. This simplifies use of the controller for cooling applications.
• Added model Buildings.Fluid.Actuators.Dampers.MixingBox for an outside air mixing box with air dampers.
• Changed implementation of flow resistance in Buildings.Fluid.Actuators.Dampers.MixingBoxMinimumFlow. Instead of using a fixed resistance and a damper model in series, only one model is used that internally adds these two resistances. This leads to smaller systems of nonlinear equations.
• Changed Buildings.Media.PerfectGases.MoistAir.T_phX (and by inheritance all other moist air medium models) to first compute T in closed form assuming no saturation. Then, a check is done to determine whether the state is in the fog region. If the state is in the fog region, then Internal.solve is called. This new implementation can lead to significantly shorter computing time in models that frequently call T_phX.
• Added package Buildings.Media.GasesConstantDensity which contains medium models for dry air and moist air. The use of a constant density avoids having pressure as a state variable in mixing volumes. Hence, fast transients introduced by a change in pressure are avoided. The drawback is that the dimensionality of the coupled nonlinear equation system is typically larger for flow networks.
• In Buildings.Fluid.Actuators.BaseClasses.PartialDamperExponential, added default value for parameter A to avoid compilation error if the parameter is disabled but not specified.
• Simplified the mixing volumes in Buildings.Fluid.MixingVolumes by removing the port velocity, pressure drop and height.

Buildings.UsersGuide.ReleaseNotes.Version_0_8_0

• In Buildings.Fluid.Interfaces.PartialLumpedVolume, added to Medium.BaseProperties the initialization X(start=X_start[1:Medium.nX]). Previously, the initialization was only done for Xi but not for X, which caused the medium to be initialized to reference_X, ignoring the value of X_start.
• Renamed Buildings.Media.PerfectGases.MoistAirNonSaturated to Buildings.Media.PerfectGases.MoistAirUnsaturated and Buildings.Media.GasesPTDecoupled.MoistAirNoLiquid to Buildings.Media.GasesPTDecoupled.MoistAirUnsaturated, and added assert statements if saturation occurs.
• Added regularizaation near zero flow to Buildings.Fluid.HeatExchangers.ConstantEffectiveness and Buildings.Fluid.MassExchangers.ConstantEffectiveness.
• Fixed bug regarding temperature offset in Buildings.Media.PerfectGases.MoistAirUnsaturated.T_phX.
• Added implementation of function Buildings.Media.GasesPTDecoupled.MoistAirUnsaturated.enthalpyOfNonCondensingGas and its derivative.
• In Buildings.Media.PerfectGases.MoistAir, fixed bug in implementation of Buildings.Media.PerfectGases.MoistAir.T_phX. In the previous version, it computed the inverse of its parent class, which gave slightly different results.
• In Buildings.Utilities.IO.BCVTB.BCVTB, added parameter to specify the value to be sent to the BCVTB at the first data exchange, and added parameter that deactivates the interface. Deactivating the interface is sometimes useful during debugging.
• In Buildings.Media.GasesPTDecoupled.MoistAir and in Buildings.Media.PerfectGases.MoistAir, added function enthalpyOfNonCondensingGas and its derivative.
• In Buildings.Media, fixed bug in implementations of derivatives.
• Added model Buildings.Fluid.Storage.ExpansionVessel.
• Added Wrapper function Buildings.Fluid.Movers.BaseClasses.Characteristics.solve for Modelica.Math.Matrices.solve. This is currently needed since Modelica.Math.Matrices.solve does not specify a derivative.
• Fixed bug in Buildings.Fluid.Storage.Stratified. In the previous version, for computing the heat conduction between the top (or bottom) segment and the outside, the whole thickness of the water volume was used instead of only half the thickness.
• In Buildings.Media.ConstantPropertyLiquidWater, added the option to specify a compressibility. This can help reducing the size of the coupled nonlinear system of equations, at the expense of introducing stiffness. This change required to change the inheritance tree of the medium. Its base class is now Buildings.Media.Interfaces.PartialSimpleMedium, which contains the equation for the compressibility. The default setting will model the flow as incompressible.
• In Buildings.Controls.Continuous.Examples.PIDHysteresis and Buildings.Controls.Continuous.Examples.PIDHysteresisTimer, fixed error in default parameter eOn. Fixed error by introducing parameter Td, which used to be hard-wired in the PID controller.
• Added more models for fans and pumps to the package Buildings.Fluid.Movers. The models are similar to the ones in Modelica.Fluid.Machines but have been adapted for air-based systems, and to include more characteristic curves in Buildings.Fluid.Movers.BaseClasses.Characteristics. The new models are better suited than the existing fan model Buildings.Fluid.Movers.FlowMachinePolynomial for zero flow rate.
• Added an optional mixing volume to Buildings.Fluid.BaseClasses.PartialThreeWayResistance and hence to the flow splitter and to the three-way valves. This often breaks algebraic loops and provides a state for the temperature if the mass flow rate goes to zero.

Buildings.UsersGuide.ReleaseNotes.Version_0_7_0

• Updated library from Modelica_Fluid to Modelica.Fluid 1.0
• Merged sensor and source models from Modelica.Fluid to Buildings.Fluid.
• Added sensor for sensible and latent enthalpy flow rate, Buildings.Fluid.Sensors.SensibleEnthalpyFlowRate and Buildings.Fluid.Sensors.LatentEnthalpyFlowRate. These sensors are needed, for example, to interface air-conditioning systems that are modeled with Modelica with the Building Controls Virtual Test Bed.

Buildings.UsersGuide.ReleaseNotes.Version_0_6_0

• Added the package Buildings.Utilities.IO.BCVTB which contains an interface to the Building Controls Virtual Test Bed.
• Updated license to Modelica License 2.
• Replaced Buildings.Utilities.Psychrometrics.HumidityRatioPressure.mo by Buildings.Utilities.Psychrometrics.HumidityRatio_pWat.mo and Buildings.Utilities.Psychrometrics.VaporPressure_X.mo because the old model used RealInput ports, which are obsolete in Modelica 3.0.
• Changed the base class Buildings.Fluid.Interfaces.PartialStaticTwoPortHeatMassTransfer to enable computation of pressure drop of mechanical equipment.
• Introduced package Buildings.Fluid.BaseClasses.FlowModels to model pressure drop, and rewrote Buildings.Fluid.BaseClasses.PartialResistance.
• Redesigned package Buildings.Utilities.Math to allow having blocks and functions with the same name. Functions are now in Buildings.Utilities.Math.Functions.
• Fixed sign error in Buildings.Fluid.Storage.BaseClasses.Stratifier which caused a wrong energy balance in Buildings.Fluid.Storage.StratifiedEnhanced.
• Renamed Buildings.Fluid.HeatExchangers.HeaterCoolerIdeal to Buildings.Fluid.HeatExchangers.HeaterCoolerPrescribed to have the same nomenclatures as is used for Buildings.Fluid.MassExchangers.HumidifierPrescribed
• In Buildings.Fluid/Actuators/BaseClasses/PartialDamperExponential, added option to compute linearization near zero based on the fraction of nominal flow instead of the Reynolds number. This was set as the default, as it leads most reliably to a model parametrization that leads to a derivative d m_flow/d p near the origin that is not too steep for a Newton-based solver.
• In damper and VAV box models, added optional parameters to allow specifying the nominal face velocity instead of the area.
• Set nominal attribute for pressure drop dp in Buildings.Fluid.BaseClasses.PartialResistance and in its child classes.
• Added models for chiller ( Buildings.Fluid.Chillers.Carnot), for occupancy ( Buildings.Controls.SetPoints.OccupancySchedule) and for blocks that take a vector as an argument ( Buildings.Utilities.Math.Min, Buildings.Utilities.Math.Max, and Buildings.Utilities.Math.Average).
• Changed various variable names to be consistent with naming convention used in Modelica.Fluid 1.0.

Buildings.UsersGuide.ReleaseNotes.Version_0_5_0

• Updated library to Modelica.Fluid 1.0.
• Moved most examples from package Buildings.Fluid.Examples to the example directory in the package of the individual model.
• Renamed package Buildings.Utilites.Controls to Buildings.Utilites.Diagnostics.
• Introduced packages Buildings.Controls, Buildings.HeatTransfer (which contains models for heat transfer that generally does not involve modeling of the fluid flow), Buildings.Fluid.Boilers and Buildings.Fluid.HeatExchangers.Radiators.
• Changed valve models in Buildings.Fluid.Actuators.Valves so that Kv or Cv can be used as the flow coefficient (in [m3/h] or [USG/min]).

Buildings.UsersGuide.ReleaseNotes.Version_0_4_0

• Added package Buildings.Fluid.Storage with models for thermal energy storage.
• Added a steady-state model for a heat and moisture exchanger with constant effectiveness. See Buildings.Fluid.MassExchangers.ConstantEffectiveness
• Added package Buildings.Utilities.Reports. The package contains models that facilitate reporting.

Buildings.UsersGuide.ReleaseNotes.Version_0_3_0

• Added package Buildings.Fluid.Sources. The package contains models for modeling species that do not affect the medium balance of volumes. This can be used to track for example carbon dioxide or other species that have a small concentration.
• The package Buildings.Fluid.Actuators.Motors has been added. The package contains a motor model for valves and dampers.
• The package Buildings.Media has been reorganized and the new medium model Buildings.Media.GasesPTDecoupled.MoistAir has been added.
  In addition, this package now contains a bug fix that is needed for Modelica 2.2.1 and 2.2.2. The bugs are fixed by using a new base class Buildings.Media.Interfaces.PartialSimpleIdealGasMedium (that fixes the bugs) instead of Modelica.Media.Interfaces.PartialSimpleIdealGasMedium. In the original implementation, initial states of fluid volumes can be far away from the steady-state value because of an inconsistent implementation of the the enthalpy and internal energy. When the Buildings library is upgraded to to Modelica 3.0.0, it should be safe to remove this bug fix.
• The package Buildings.Fluid.HeatExchangers has been revised and several models have been renamed. The heat exchanger models have been revised to allow computing the fluid volumes either dynamically, or in steady-state.
• The damper with exponential opening characteristic has been revised to allow control signals over the whole range between 0 and 1. This was in earlier versions restricted. In the same model, a bug was fixed that caused the flow to be largest for y=0, i.e., when the damper is closed.
• Additional models for psychrometric equations have been added. The new models contain equations that convert dew point temperature and water vapor pressure, as well as water vapor concentration and water vapor pressure.
• A new mixing volume has been added that allows latent heat exchange with the volume. This model can be used to model a volume of moist air with water vapor condensation inside the volume. The condensate is removed from the volume in its liquid phase.

Buildings.UsersGuide.ReleaseNotes.Version_0_2_0

Buildings.UsersGuide.ReleaseNotes.Version_0_1_0

First release of the library.

This version contains basic models for modeling building HVAC systems. It also contains new medium models in the package Buildings.Media. These medium models have simpler property functions than the ones from Modelica.Media. For example, there is medium model with constant heat capacity which is often sufficiently accurate for building HVAC simulation, in contrast to the more detailed models from Modelica.Media that are valid in a larger temperature range, at the expense of introducing non-linearities due to the medium properties.