VisCalc Module 2

Friction Theory Blending Package

This is a proprietary unique module for the prediction of the properties of commingled fluids using state-of-the-art Friction Theory models. This module consists of two basic units:

  • Blend generation.
  • Blend reduction.

1.1 Blend generation

When a fluid is characterized using Module 1, a text file of parameters is automatically incorporated in a library of already characterized fluids. Module 2 may also produce another fluid (a blend) for which a similar text file can be generated, which in turn can also be incorporated to the library of characterized fluids. That is, the library of characterized fluids may be composed by basic fluids and/or commingled fluids. All this is done on a continuous space, not on discretized fluids, resulting in files of parameters always of the same structure (regardless whether they represent basic fluids or blends).

Out of the library of available fluids, the user can choose what fluids (basic or blends) will be further used in the elaboration of a new blend.   This sub-module will first read the characterization parameters for each of the fluids that may integrate the new blend. Subsequently it will make use of the most advanced Friction Theory mixture models we have developed, some of which are not of public knowledge, and predict with a high degree of accuracy the viscosity behavior of the suggested blend. The capabilities of our current approach are depicted in Figure 2.1, which illustrates the predictions that can be achieved when a light fluid is blended with a heavy one. This case shows the FT models performance on a full four orders of magnitude viscosity variation at 20 ºC. As this figure illustrates, even in such an extreme case, the blend prediction results fall within the experimental uncertainty.


Figure 2.1. Viscosity prediction results for a blend between a light and a heavy fluid.

1.2 Blend reduction

This is an extremely powerful proprietary sub-module. Once a blend has been defined and the user decides to keep it as a reference fluid, the routines in this sub-module will eliminate all mixing rules and reduce the blend to a single fluid. In this way a parameters file with exactly the same structure as those files that are generated in Module 1 is produced. The result is that the new blend can now be treated as one more basic fluid and further used for commingling with other fluids. Even a template similar to the one that is directly filled from a pvT laboratory report is automatically generated with predicted blending data. This allows for the results to be exported, compared and tested with other applications the user may consider.

In summary, at the end of this procedure we may have a new fluid that may be considered as one more basic fluid in spite of being the product of the commingling of a number of basic fluids and/or previously made blends. A distribution function form which new pseudo-compounds can be derived represents this new fluid. The new fluid can be blended again, and again, and combined with other basic fluids or blends as much as it may be required and new fluids, product of successive blending, can be produced and recorded.

Similar to the Module 1, the final step of the Bending Module is the generation of well-defined text files with the specific blended fluids characterization parameters. These files can also be further read to generate reports that may include tables of properties or even a pseudo-compounds EoS pvT representation of the fluid for exporting purposes into other applications.

2 Software example

The results just descried have also been incorporated into an user-friendly software. Couple examples of screen-shots of a version in Spanish are shown in Figure 2.2, multiple languages are an option of our VisCalc software. The example 2.2a corresponds to a two-fluids blend while the 2.2b to a more general blend. The software is capable of fast calculations allowing a dynamic interaction with the engineer working on the definition of optimal blends. In fact, two fluids blend can be made by simply dragging the mouse along the density plot shown in the lower part of the Figure 2.2a. In the case of multiple-fluids blends, the interface shown in Figure 2.2b is provided.

Figure 2.2. Screen dump for two fluid and multi-fluids blends.

F-Thermo Services GmbH
Zülpicher Str. 58b
50674 Cologne, Germany