Data for Academic Use
How can I access DDB data as a researcher at an academic institution?
- First step could would be to install the free explorer version containing a lot of data for the 30 common compounds and their mixtures.
- The educational version contains all data for the 30 common compounds and their mixtures.
- If you are interested in data for a certain compound or mixture, look at our online search (Prices are given here)
- If you are interested in all data or a large subset of the data for one or more properties (VLE, LLE, …), licensing a database is a good option. There is a 50% academic discount but 1-year only licenses are not available
for universities. Subset prices (e.g. all alcohol-alkane data) can be calculated upon request.)
Empty Data Sets in the DDB
In addition to the data licensed by my company or the few demo data it is possible to display empty sets (checkbox in the top of the data set table in the DDB Query result dialog). What is this about?
- In addition to the licensed and demo data (in the free Explorer version only demo data) your installation contains a complete directory of all DDB data sets. Data sets not available in your license are "empty".
You can request these data from support@ddbst.de or preferably via our online search (Prices are given here).
Literature Data Missing in the DDB?
I checked for certain data and found out that data from a reference are not stored in the DDB
- We at DDBST try to cover the data available in the open literature to the highest possible completeness. Stored data come from open literature and other sources and only experimental data from the
original reference are considered. Data from confidential reports and own measurements are usuall available only via the DDB.
If you are aware of data missing in the DDB we would gratefully appreciate any information that would help us to also include these measurements. If you should have data from sources
like MSc. or PhD.
theses or the like we would be happy to have a copy available so that we can enter also this data.
Artist Group Fragmentation
Why are group fragmentations not consistent with e.g. groups used in the Aspen-simulator?
- Aspen Tech is using a different fragmentation algorithm that may produce undesirable results in some special cases. In addition, some groups are defined in a more strict way in Artist leading to different results.
Where are the group definitions for the different methods stored?
- Usually these definitions are stored in files with the extension ink. In a typical installation, most of these files are integrated into the code and therefore are not on the DDB-directory. If a file like e.g. UNIFAC.ink is
stored on the DDB-directory, it is used instead of the UNIFAC.ink that is integrated into the code. This is for example important for the Consortium members, who have a special consortium UNIFAC.ink, UNIFACDO.ink
, … on their DDB-directory.
Entrainer Selection
Why does the entrainer selection program find no suitable entrainer for the system acetic acid/water.
- The entrainer selection software would usually find a list of entrainers. If you entered a low temperature for the separation (e.g. T=323 K), the pure component vapor pressures of acetic acid and water are 8.4 kPa resp. 13.5 kPa.
These values together with the other limiting condition that the "Minimum Vapor Pressure Difference Entrainer - Binary Mixture" must be -10 kPa leads to the effect that no component can meet this criterion (would be Psat<(8.4-10) kPa, a negative value).
Suitable entrainers can therefore only be found if you increase the temperature to a higher value where the lower saturated vapor pressure of the both components exceed this 10 kPa barrier or lower the value of the minimum vapor pressure difference.
If you choose e. g. T=350 K some entrainers will be found.
COSMO-RS Calculation
Where are the sigma-profles for the calculation stored and how do I add profiles from my own quantum chemical calculations?
- The sigma profiles are usually stored under a special directory under your public DDB. In order to use your own calculation results the .cosmo file first has to be averaged. Please look
here for details.
How do I set a different directory for the sigma profiles?
- In the private DDB directory (start "DDB Configuration" from the jumpstart menu to identify it's location) there may be a text file called "ddbsp.ini". If it does not exist, create a textfile with this name. Add the following two lines to this file:
[COSMO]
path=< path to .cosmo directory>
The path must end with the character "".
The directory must include the subdirectories "cosmo-rs(ol)" and "cosmo-sac" with the averaged profiles. Please look
here for details about the averaging.
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