Pressure Loss & Transfer Coefficients

The new version of the software gives a graphical representation of both the transfer coefficients and pressure drop contributions of the various relevant components of the cooling tower. These values will help cooling tower designers to identify areas that can be optimised to improve cooling tower performance. Higher transfer coefficients and lower pressure drop values are generally required for optimal performance. The next two graphs give the relative contribution of the cooling tower components to the transfer and pressure drop respectively.

Transfer Contribution

Pressure Drop Contribution

Plenum Chamber & Fan Coverage

The new version of the software has a visual tool to help the designer to evaluate the fan coverage ratio and angles. These variables are checked against API recommended values. The coverage angle is indicated in green when it complies to API requirements. It will be indicated in red if the fan coverage falls outside API recommendations.

Fan Coverage

Software Convergence

The new version of the software that is under development will inform the user about the convergence of the solution algorithm. It was mentioned in a previous blog post that the software employs an iterative solution scheme. The image below shows how much the solution variables changes from one iteration to the next. The algorithm will stop when the tolerances of all the solution variables are below pre-defined values. These tolerance levels are also indicated on the graphs. It is evident that the water outlet temperature, or Two, was the last variable to reach the predefined tolerance level. The values on the y-axis are shown on a log scale.

Convergance Tolerance

The next image shows how the values of the solution variables converge to the final values.
Convergance Values

Supersaturated psychrometric chart

The new version of the software will generate psychrometric charts, showing the path of the air as it moves through the cooling tower. This visual graphical representation will aid cooling tower designers in designing hybrid cooling towers, ensuring that outlet air is unsaturated, thus eliminating visible plumes.

An example where the inlet air is already saturated with water vapour is shown below. The air becomes becomes supersaturated as it gets in contact with the water.

Psychro Supersaturated

Here is an example where the inlet air is hot and dry.

Psychro HotDry

The psychrometric saturated chart will be a standard feature of the new software.

New software version under development

I am excited to let you know that I am working on a new version of the software. The first version of the software was developed as a tool to do academic research. It was therefore not necessarily very user friendly as it included many futures that were not needed for the practical design of cooling towers. The software served its purpose as many journal articles were published using it. Some of the features in the original version will be excluded in the new version. Some of these excluded features are:
  • Input humidity profiles
  • Different integration options for the Merkel method (i.e. Simpson, trapezoidal rule)
  • Some of the iteration parameters like tolerances and the maximum number of iterations in the Poppe method will be removed.

There is unfortunately not an expected date of completion at the moment, but I will publish updates on the progress.
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