Vapor Cycle Library - Release Information

Version 1.3 contains the changes described below.

Improvements

  • Improved simulation speed, through reduction of expensiveness of the media property function calls.
  • Improved Modelica compliance.
  • Improved Tutorial.
  • Improved documentation for the heat exchangers.
  • Improved icon layout.

Fixed issues

  • Kandlikar evaporationheat transfer coefficient correlation has been corrected. The change is expected to have an impact on heat exchanger results only, if the secondary side is not limiting the heat transfer. The erroneous correlation is included in this release for compatibility reasons but will be removed in subsequent releases.
  • Chen evaporation heat transfer coefficient correlation has been corrected. The change is expected to have an impact on heat exchanger results only, if the secondary side is not limiting the heat transfer. The erroneous correlation is included in this release for compatibility reasons but will be removed in subsequent releases.

Conversion of user libraries

Automatic conversion of user libraries from version 1.2.2 is supported using the included conversion script convert_to_1.3.mos located under LibraryName\Resources\Scripts.

Requirements

Vapor Cycle 1.3 is based on the Modelon base library 2.4 and Modelica Standard Library 3.2.2. It can be combined with Liquid Cooling Library 1.5 and Heat Exchanger Library 1.4.1.

It has been tested with:

  • Dymola 2016 FD01
  • Dymola 2017

Version 1.2.2 contains the changes described below.

Improvements

  • Improved Modelica compliance
  • Improved documentation

Conversion of user libraries

There is no need for conversion of user libraries.

Requirements

Vapor Cycle 1.2.2 is based on the Modelon base library 2.3 and Modelica Standard Library 3.2.1. It can be combined with Liquid Cooling Library 1.4.1 and Heat Exchanger Library 1.4.

It has been tested with:

  • Dymola 2016 FD01
  • Dymola 2016

Improvements

  • Improved Modelica compliance.
  • Improved Tutorial.
  • Improved documentation for the heat exchangers.

Conversion of user libraries

There is no need for conversion of user libraries.

Base library

Vapor Cycle 1.2.1 is based on the Modelon base library 2.2 and Modelica Standard Library 3.2.1. It can be combined with Liquid Cooling Library 1.3.1 and Heat Exchanger Library 1.3.

This library has been tested with:

  • Dymola 2015 FD01
  • Dymola 2016

Available for: Dymola 2014 FD01

DependenciesModelica Standard Library Version: 3.2

Conversion: None from 1.8.4

  • A new information section is included directly in the library, with guidelines on component testbench and cycle initialization.
  • Handling of refrigerant properties at the receiver outlet is improved for low or zero-flow simulations.
  • In- and outlet pressures, enthalpies and pressures in heat exchanger summary records properly take into account headers, in case those are activated. Previously, only the active heat exchanger part was considered for temperature and enthalpy variables. Enthalpy deviations from previous results are only expected, if heat transfer between headers is possible, temperature may be slighthly different in the two-phase region, due to the additional pressure drop in the headers. This concerns only summary variables, other model variables are unaffected.
  • The variability of correction factors for heat transfer and pressure drop in heat exchangers (CF_ ...) has been increased. They are now declared as input variables, which may change over time. As a feature request by many users, this increases the flexibility for user defined modifications. The default behavior of existing models is not expected to change. Manual steps may be required for the conversion of models for pressure drop and heat transfer correlations, which were copied and modified from previous versions of the library. Please, contact support, if you experience problems.
  • Display units in the four-value display visualizer are corrected to be consistent with the actual value.

New features

  • A static reversible valve , which can be used in architectures that change operation mode.
  • A turbine model parametrized with a mass flow lookup table and a efficiency look up table.
  • A compressor model with a parametrisation suitable for dynamic compressors. It is parametrised with an isentropic efficiency table and a mass flow table.
  • An ORC example experiment has been added to the libary
  • A bend component has been added to the library.
  • A counterflow internal heat exhanger has been added to the library.
  • Visualizers for all working fluids have been added to the library.
  • The library contains a new User's Guide and two Tutorials.

Improvements

  • Turbine or the compressor face correct inlet density also for two-phase inlet now. The default characteristics however do not take into account performance deterioration because of liquid at the inlet.
  • All heat transfer correlations and pressure drop correlations for pipes have been moved in order to improve user friendliness when working with a combination of different Modelon libraries. Their description and information is updated. Running the included conversion script is necessary for this update.
  • The default two phase medium model has been changed from R134a, reference properties by Tillner-Roth to R134a, short form Helmholtz EOS by Span. Its accuracy is slightly lower but still more than sufficient more most applications. The simulation speed is increased significantly with the simpler model.
  • Both the receiver and accumulator can be initialized using a liquid level.
  • Adding specific interfaces to the heat exchanger models increased replaceability and reusability of the models in a system context.
  • The default air model is replaced with one, which is better suited for challenging steady-state initialization. Basically the same assumtions apply except that the new model neglects the liquid volume in case liquid water droplets are transported by the air stream and assumes that they do not influence the specific heat capacity. The previously used model can still be selected from a drop-down list.
  • The medium model for CO2 has an improved robustness around the critical point.

Fixed bugs

  • An error in the modified Dittus-Boelter function, which is used in heat transfer correlations for evaporation has been fixed. The change is expected to have an impact on heat exchanger results only, if the secondary side is not limiting the heat transfer.
  • A small error in the heat transfer correlation for both evaporation and condensation has been fixed. The change is expected to have an impact on heat exchanger results only if the secondary side is not limiting the heat transfer.

Conversion of user libraries

Automatic conversion of user libraries from version 1.1 is supported using the included conversion script convert_to_1.2.mos located under LibraryName\Resources\Scripts.

Base library

Vapor Cycle 1.2 is based on the Modelon base library 2.1 and Modelica Standard Library 3.2.1. It can be combined with Liquid Cooling Library 1.3. and Heat Exchanger Library 1.2.

This library has been tested with:

  • Dymola 2015 FD01
  • Dymola 2015

28-05-2014

Available for: Dymola 2015

Dependencies: Modelica Standard Library Version: 3.2.1 and Modelon Base Library 2.0

New components:

  • A pump model with several different options for defining flow and power characteristics.
  • A turbine model with flow rate determined according to the Stodola law and a given nominal operating point. Constant isentropic and mechanical efficiency are assumed.
  • Splits and junctions with different options to define the flow resistance
  • A working fluid flow source which may be used to remove or add charge in a closed cycle according to a given setpoint.
  • Automatic aggregation of working fluid volume and mass in a system, see system examples for details.
  • A multi-port volume
  • An interface to the NIST REFPROP data base. Any single-component fluid from REFPROP can be included easily in the drop-down list for possible working fluids. REFPROP and its license have to be available on the computer and are not part of this library.

Improvements

  • Computational speed in medium property functions was increased by factor two.
  • Temperature is introduced as an alternative input to specific enthalpy in working fluid sources and sinks

 

Available for: Dymola 2014 FD01

Dependencies: Modelica Standard Library Version: 3.2.1 and Modelon Base Library 1.9

Features:

  • The library contains all components necessary to build a vapor-compression thermodynamic cycle
  • Wide range of refrigerants and other potential working fluids.
  • Heat exchangers form the interface to other fluid domains, such as air flow and liquid coolants
  • A wide range of working fluids, see package Media.
  • Two- and one-phase fluid flow with a choice of different heat transfer and pressure loss correlations that also cover phase change.
  • Ready-to use component models with example parameterization as well as interfaces and templates for user-specific modifications.
  • System examples that demonstrate the use of the library.