Heat Exchanger Library - Release Information

Improvements

  • Added spatial temperature plots in plate heat exchanger test benches.
  • Test benches for gas-gas and liquid-liquid plate heat exchangers previously imposed that the same medium was used on both sides. This has been fixed.
  • Signal components that define boundary conditions in plate heat exchanger test benches are now replaceable.
  • Improved steady-state initialization robustness for flat tube heat exchangers.
  • Restructured condenser with integrated receiver to avoid conditional components which have limited access of variables.
  • Added the possibility to modify the solid mass of flat tube heat exchangers. This can now be done by a mass offset or scaling factor in the geometry record.
  • Improved compliance with the Modelica specification.
  • Improved documentation.

Bug fixes

  • Fixed an error where air side pressure drop over a multi-layered heat exchanger was not correctly computed in a stack configuration.
  • Fixed an error in Chevron plate heat exchanger heat transfer and pressure drop correlations by Chisholm. This fix affects simulation results and existing user models are converted to use the previous implementation by the provided conversion script.
  • Fixed an error in Chevron plate heat exchanger pressure drop correlation by Martin. This fix affects simulation results and existing user models are converted to use the previous implementation by the provided conversion script.
  • Fixed errors in two-phase heat transfer correlations by Chen and Kandlikar. These fixes affect simulation results and existing user models are converted to use the previous implementations by the provided conversion script.
  • Fixed an error in the summary record of condenser with integrated receiver. Outlet conditions were taken from the incorrect component.
  • Fixed an error in the propagation of steam quality plot variable in flat tube test benches. This caused quality not to be properly plotted in spatial plots. This fix does not affect simulation results.

Conversion of user libraries

The provided conversion script can perform all required conversions of user models. The script is available at modelica://HeatExchanger/Resources/Scripts/Convert_to_1.4.1.mos

User models using correlations affected by the bugs described above will be converted to deprecated correlation models to avoid result differences after conversion.

Requirements

Heat Exchanger Library 1.4.1 is based on Modelon Base Library 2.4 and Modelica Standard Library 3.2.2.  

It has been tested with:

  • Dymola 2017

Improvements

  • Improved compliance to the Modelica specification 3.3 rev 1.
  • Fixed an error that medium model definitions could not be displayed in the text layer.
  • Improved heat exchanger parameter dialogs

Conversion of user libraries

User models based on Heat Exchanger Library 1.3 does not need any conversions.

Requirements

Heat Exchanger Library 1.4 is based on Modelon Base Library 2.3 and Modelica Standard Library 3.2.1.  

It has been tested with:

  • Dymola 2016 FD01
  • Dymola 2016


Version 1.3 contains the changes described below.

New features

  • Gas-liquid plate heat exchangers components with plain plate surface, to be used in both counterflow and co-flow.
  • Gas-liquid plate heat exchangers components with Chevron plate surface, to be used in both counterflow and co-flow.
  • Liquid-liquid plate heat exchangers components with plain plate surface, to be used in both counterflow and co-flow.
  • Liquid-liquid plate heat exchangers components with Chevron plate surface, to be used in both counterflow and co-flow.
  • Gas-gas plate heat exchangers components with plain plate surface, to be used in both counterflow and co-flow.
  • Gas-gas plate heat exchangers components with Chevron plate surface, to be used in both counterflow and co-flow.
  • Testbenches for plate heat exchangers: gas-gas, liquid-gas and liquid-liquid.
  • A set of heat transfer and pressure drop correlations for Chevron plate heat exchangers.
  • A new two-phase/air flattube heat exchanger component which contains a receiver after a given pass.

Improvements

  • Improved in library documentation, in particular for the Kandlikar correlation.
  • Improved Modelica compliance.

Library structure changes

Renamed classes

  • HeatExchanger.HeatExchangers.Experiments -> HeatExchanger.HeatExchangers.FlatTube.Experiments

Conversion of user libraries

Automatic conversion of user libraries from version 1.2 is supported using the included conversion script.

Requirements

Heat Exchanger Library 1.3 is based on Modelon Base Library 2.2 and Modelica Standard Library 3.2.1.  

It has been tested with:

  • Dymola 2015 FD01
  • Dymola 2016

New features

  • Added support for moist air and condensation on the ambient side of the heat exchanger
  • Added an optional, more detailed representation of the air side pressure drop and heat transfer. This option is selectable from the heat exchanger paraemter dialog, and is optimized for simulation of stand-aone heat exchangers with high resolution gridded boundary conditions. The original implementation is also available and is recommended for use in heat exchanger stack models.
  • Added the possibility of computing the total internal liquid or working fluid volume and mass. When included in a system model based on the Liquid Cooling Library or Vapor Cycle Library, the total properties will be computed for the whole system including the heat exchanger.

Improvements

  • All user calibration factors for heat transfer and pressure drop has been converted from parameters to inputs. Users may still assign them with fixed values in the parameter dialog, but can now also use variable expressions to define calibration factors.
  • Improved in library documentation.
  • Improved Modelica compliance.
  • Updated for compatibility with Modelon Base Library 2.1

Bug fixes

  • Fixed an error that caused models with internal discretization orthogonal to the flow direction not to be able to translate in some configurations.

Conversion of user libraries

Automatic conversion of user libraries is supported using the included conversion script.

Base library

HXL 1.2 is based on the Modelon Base Library 2.1 and Modelica Standard Library 3.2.1.

08-05-2014

Available for: Dymola 2015

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

Conversion from: 1.0,.1.0.1, 1.0.2

Heat Exchanger Library 1.1 is a major release with new features and other improvements.

New features

  • Flat tube type air - gas components have been added. These are designed to model charge air coolers, stand alone or as part of a stack model.
  • Flat tube type air - two phase components have been added. These are designed to model evaporators and condensers, stand alone or as part of a stack model..
  • A new type of fin geometry has been added. In addition to the louvered fin types, off-set strip fins can now be modeled. Design correlations as described by Manglik & Bergles are included for pressure drop and heat transfer. The new fin type is available for all of the included heat exchanger types.
  • It is now possible to discretize the flat tube internal flow orthogonal to the flow direction by the new parameter "n_orthogonal" for the air - gas and air - liquid heat exchangers. The wall is always discretized with the same number of segments as the internal flow channel. Currently the number of flow orthogonal segments is equal in all passes.
  •  Heat exchanger test benches are now included. These include automatic definitions of the air segmentation grid from user defined segmentation numbers and heat exchanger geometry, and spatial ploting of fluid, wall and air temperatures.
  • Added exhaust as selectable medium for gas in air - gas heat exchangers, represented as an ideal gas mixture of CO2, H2O, O2 and N2.

Other improvements

  • The fin flow resistance correlations for louvered fins by Kim & Bullard and by Chang, Hsu, et. al. have been protected against division by zero at zero mass flow rate.
  • Parameters defining the flow resistance of air flow bypassing the heat exchanger in a stack was not propagated to the top level of the heat exchanger. This has been fixed.

Changes to model structure

In order to support all different heat exchanger types using common base classes, there has been some changes to the internal structure of the model with this release.

  • A common template "PartialFlatTubeHX" for all flat tube type heat exchangers has been created. This defines the air side model and a replaceable internal flow channel. All geometric parameters are propagated from the geometry record to the flow channel components.
  • A separate template for each of air - gas, air - liquid and air - two phase has been created. These define the flow channel model of the internal flow and parameters for the specific type of heat exchanger. The template "PartialFlatTubeInternalLiquid" replaces the previous "AirCoolantBase".
  • The geometry records have been structured in a hierarchical way so that the air side geometry is defined in a class common for all types of heat exchangers.
  • The discretization of the wall has been changed from a single dimension defined from flow inlet to flow outlet, to a 3D discretiztion with dimensions x, y, z. This allows the orthogonal segmentation of the internal flow within passes.
  • The record "AirChannelGeo" which is used to propagate fin geometry from the main geometry record to the flow resistance and heat transfer correlations has been slightly modified so that it only includes parameters of the fins. This allows use of the same record for propagating parameters for fin on both the air and gas sides in the air - gas heat exchanger.

 

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.

Available for: Dymola 2014 FD01

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

  • Heat Exchanger Library 1.0.1 is a minor release for compatibility with the Modelon Base Library 1.9 and Modelica Standard Library 3.2.1
  • An error in the computation of heat transfer area on the liquid coolant side have been fixed. This error had little impact on typical components where the air side is the major limiting factor for the total heat transfer.
  • The internal coolant channel can be initialized with a temperature gradient in the flow direction by specifying the initial inlet and outlet temperatures.
  • The wall component is now replacable.
  • The summary record variable T_in now shows the actual inflowing temperature, rather than that of the first control volume

Introduction

Heat Exchanger Library (HXL) is targeted to heat exchanger design, dimensioning, and stacking. HXL contains flat tube heat exchanger models supporting several flat tube and louvered fin designs. The models accounts for effects of inhomogeneous air flow and temperature distribution and it is possible to model heat exchanger stacking along the air flow path.

The library is suitable for studying the effects of heat exchanger dimensioning and positioning on cooling performance. HXL has a native interface to the Liquid Cooling Library (LCL) for complete thermal management design. The models can be coupled to CFD-derived boundary conditions on the air side, bridging the gap between CFD and system simulations.

Main features

Highlight features of the library are:

  • Geometry based heat exchanger models for system simulations
  • Friction and heat transfer models for louvered fin designs
  • Captures effects of inhomogeneously distributed inlet air flow
  • Coupling to CFD data
  • Modeling of heat exchanger stacks with different heat exchanger geometries, sizes and positioning

Base library

HXL 1.0 is based on the Modelon base library 1.8.