Tags and keywords
It is assumed that where the example question is asking for 'how much outside air is needed per minute' it is asking for the volumetric flow rate of the humid air mixture. The result given is in fact for the "entry" State1:
The course PDF Answers (where available) from the worked example problem are given in the 3rd column in the custom table in the top of the image in IP units.
When handled by the MPsy class, we have 2 objects representing the before and after states. Note how the humidity ratio 'w' of the 1st object is used to set the humidity ratio of the 2nd object, because it is assumed that there is no change in the contained water mass within the humid air.
The 2nd table that shows the differences between them, as well as indicating the change in each main psychrometric variable, and the "direction" of change.
We see that for such a humidification process:
- The humidity ratio 'w' and the dew point temperature 'tdp' increase.
- The mass-specific enthalpy per dry air 'hda' increases.
There is a dedicated Psy library function for calculating the required volumetric humid air mixture flow rate for this humidification case.
The psychrometric chart function shows both states, as well as an arrow indicating the change.
In the next slide we see how such humidification can be represented as a 2-step (3-state) process.