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Friday, 11 January 2013 22:11

Fire zones

Question:

Can Flownex design and model fire zones?

Answer:

No.

 

Published in Simulation
Saturday, 12 January 2013 04:04

Smoke extraction

Question:

What smoke extraction simulation (like in HVAC systems) capabilities does Flownex have?

Answer:

Flownex cannot model smoke generation. However, it is possible to build a 3-D representation of a building (using a 1-D approach) and to predict where concentrations of a contaminant will disperse. This is based on the pressure difference and concentration different between adjacent volumes.

 

 

Published in Simulation
Friday, 23 November 2012 16:00

Mixtures

Question:

Why is it that Flownex gives me an error message when I select gases and liquids at the same time, whilst there are gases and liquids in the Mixed Fluids dialog?

Answer:

When Flownex gives you an error message, then it simply means that Flownex cannot make that specific mixture.

Published in Simulation
Friday, 23 November 2012 18:00

Steam generation model

Question:

What could be possibly wrong with my Steam generation model if I keep getting the warning: “WARNING, Quality at compressor inlet/exit is smaller than 1. The set of dimensionless parameters were derived for gasses. Evaluate solution, Solve Steady State”?

Is the fluid (two-phase water) supposed to be pure vapor as it enters/leaves the compressor?

Answer:

A compressor is designed such that a fluid in its gas phase has to be supplied at the inlet. Thus, the quality must be close (for a compressor that can handle a wet gas) and larger than 1. A quality of a value less than 1 means that the compressor is compressing water which is in a liquid phase. For these operating conditions, compressors will not work because water in a liquid phase is a noncompressible fluid. That is why Flownex gives a warning.


Published in Simulation
Friday, 23 November 2012 14:00

De-rating model

Question:

I’m trying to work through the slurry setup available in theory manual under section 7. When I assign the multi-curve pump, I do not get the option to apply a De-rating model to the pump.  What is the reason why the option shown in figure 7.28 wouldn’t show?

Answer:

The option was also not directly available to me when I worked through the example, what I've done was to save my project and reloaded it. After doing that, the option “Apply De-rating model” was available to me.

 

Published in Simulation
Friday, 23 November 2012 12:00

Positive Displacement compressor

Question:

If my working fluid is a liquid, can I make use of the positive displacement compressor?

Answer:

Make use of a pump component.

 

Published in Simulation
Friday, 23 November 2012 06:00

Multiple restrictor error

Question:

When using multiple restrictors with loss coefficients the following error appears:

"ERROR, Independent variable Restrictor with Loss Coefficient - 41 -  
     User Description is not of type IPS::Properties::Double. Designer
     aborted, INACTIVE

How do I correct this?

Answer:

A flow-solver error property needs to be changed:

1. In the Flownex library tree, click on the Solver/Utilities tab.

2.  Select ‘Flowsolver’.

3. Uncheck “Treat phase change warnings as errors” in the Inputs tab.

4. Run the designer again to see if it works.

 

Published in Simulation
Friday, 23 November 2012 08:00

Fluid quality

Question:

Does the property quality in "Flow and Geometry variables" of the results tab not indicate "dryness level" rather than humidity? The value is often minus or more than 1. If the property is quality, should it not be between 0 and 1?

Answer:

According to the traditional thermodynamic definition, it is correct to assume that Quality should be between 0 and 1, because it is an indication of the quality in the two-phase region. What Flownex does in the case when a fluid is super-heated (e.g. all the water turned into steam), then the Quality is indicated as a value above 1. When the fluid is fully saturated (e.g. only liquid water is present), then Flownex indicates a negative Quality value. Therefore, as implemented in Flownex, the thermodynamic definition of quality has been extended to indicate when the fluid is not in the two-phase region.

 

Published in Simulation
Friday, 23 November 2012 08:00

Abnormal Designer termination

Question:

When a wrong input is made in a component’s property entry and the escape button ‘esc’ is pushed during the Designer procedure, the Designer often terminates abnormally. What causes this?

Answer:

When trying to stop the Designer, rather use the Deactivate button on the Simulation Control tab on the Ribbon to stop the calculation process.

 

Published in Simulation
Friday, 23 November 2012 08:00

Deleting projects

Question:

How do you delete a project from the Flownex project tree?

Answer:

The project tree allows you to delete pages inside the project. The project as a whole can be deleted in the explorer. Flownex can only have one project opened at a time; however a project can have multiple pages. 

 

Published in Simulation
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