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Found via `codespell -i 3 -w -I ../coolprop-word-whitelist.txt` whereby whitelist consists of: ``` cas formate hel nd te tim ue uint ```
69 lines
2.5 KiB
ReStructuredText
69 lines
2.5 KiB
ReStructuredText
CoolProp Delphi Wrapper Demo.
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=============================
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Bruce Wernick, info@coolit.co.za
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13 December 2015
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project4 is a demo based on the win32 shared DLL downloaded from the CoolProp
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site.
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There are two parts:
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1. The actual DLL interface.
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2. A simple ph-chart builder.
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The original CoolProp code is written in C++. In the CoolProp source folder,
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you can find the text file exports.txt that details the complete list of functions
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exported by the CoolProp DLL.
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I have only implemented the essential ones but it would be
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easy to add any I have omitted. My interface mimics the C header file
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but there are a few considerations. The returning string is an array of char.
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In Delphi, you could use an array of AnsiChar parameter. Instead, I chose to use
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the PAnsiChar because it makes the dll interface clearer and more universal.
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One thing you have to be aware of - the calling program has to allocate memory
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for the result. If this is not sized sufficiently, then a blank string is
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returned. This could happen, for example, if a lot of fluids are added to
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the file.
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The graphical part draws the saturation curve on conventional log(p) vs enthalpy
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axes. The program main form has a Delphi VCL TListView and a TPaintBox.
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On startup, the program uses the DLL to populate the ListView with all of
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the available fluids. The PaintBox is a very basic components that is really
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just a canvas. The main program creates a TMolChart class that does all the
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work on a canvas. When the OnPaint fires in the main form, the chart is re-drawn.
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See the project4 output here
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.. image:: project4.png
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:width: 40pt
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The chart is auto scaled around the critical point and atmospheric pressure
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(where possible). This makes it quite convenient for comparing the shape of
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the various saturation curves. What it needs is some isotherms and some
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isentropic lines. If anyone has the urge to add these I would like to get
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an update.
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Just to highlight some of the other features, I have added a few simpler command line
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versions.
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Lazarus users
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-------------
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With some minor changes, you could quite easily run this code with Lazarus.
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Floating Point Exceptions
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-------------------------
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A note about some specific problems that I found with Delphi.
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Apparently, most compiers automatically disable floating point exceptions. The
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Delphi compiler does not do this. Actually, this does not fix the problem, it
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simply hides it.
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You can see the errors on this image
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.. image:: coolprop_error01.png
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:width: 40pt
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