Using the Compound Editor

The Compound Editor is a new feature in CADSIM Plus v2.6. It allows you to perform two related functions: creating a new user-defined chemical compound for use in CADSIM Plus, or overriding one or more properties of an existing CADSIM Plus compound. The compound editor replaces the previous physical properties override mechanism that was introduced with CADSIM Plus v2.4.

The Compound Editor is invoked from the Stream Definition (SDEF) Wizard, where you can select and edit the properties of an existing compound, or create a new compound. The Compound Editor allows you to name your new compound, specify its molecular formula, (optionally) base its chemical properties on another existing compound and choose which categories the new compound will appear under (such as liquids, gases, etc.) in the SDEF wizard.


Once the basic information for the new compound has been established, you can click on the individual property tabs to enter your own chemical properties data. Or, you can choose to use the specified property of another known compound on a per-property basis. Note that if you decide not to explicitly select data for each of the available properties, those properties that are not set up will use the properties of some default compound (eg. water is the default for liquids in water-based streams, and methane is the default for liquids in HyProc streams).

Some chemical properties may be described by a simple constant value, while others may require a choice of one of several supported equation types. Supported equation types include Shomate, Polynomial, Yaws Antoine and Rational. Note that some properties, such as Vapor Pressure, require data to be in a specific format, such as the three coefficient Antoine equation.

Specific properties may require additional information. For example, much of the available chemical properties data is only valid within a specified (tested) temperature or pressure range. Setting this range on a property page will prevent CADSIM Plus from doing something that is unpredictable, if the compound is used outside of that range. However, you need to be aware that property data that is used outside of its range will produce less accurate simulation results.


It is important to set up test models to insure that the results of your properties customizations meet your expectations. One useful method of inspecting custom properties, is to use the PROPERTIES module in your test drawing, which exposes the current data for each chemical property of the selected compound using current stream conditions. Sometimes re-correlating the data (eg. from polynomial to rational) can allow the range of accuracy to be significantly expanded.

Chemical property data can be obtained from several different sources. You may have assay lab data from your own research or from a university or research organization. Or you may wish to purchase data from an organization such as DECHEMA, which provides online access to thermophysical property data for about 36,500 compounds and 124,000 mixtures. There are many other sources of properties data available on the web and in reference books.

The Compound Editor automatically stores your customized compound data in the current CADSIM drawing file. Compound data is shared between all stream definitions in the drawing, meaning that if you override the boiling point rise of water, it will have the same effect in all of the stream definitions in your current drawing/model.

There is also a report mechanism built into the Compound Editor, that allows you to generate a report of all of the customized compound properties in your model.

You can also export customized properties data to an external XML formatted data file, which can then be imported into other CADSIM Plus drawings, allowing you to reuse the data in other CADSIM Plus models.

The Compound Editor allows you to create comprehensive compound properties, or to simply create aliases to existing compounds. The choice is yours.