Tags and keywords
It is assumed that where the example question refers to '20 lb of air' it is referring to the mass of dry air.
The course PDF Answers (where available) from the worked example problem are given in the 3rd column in the custom table at the top of the image in IP units.
When handled by the MPsy class, we have 2 objects representing the before (State 1) and after (State 2) states, as well as an object representing the intermediate "State 0" when modelled as a 2-step process.
The 2nd table shows the differences between State 1 and State 2, as well as indicating the change in each main psychrometric variable, and the "direction" of change.
There is a dedicated Psy library function for calculating how much moisture is added for this humidification case.
The psychrometric chart function shows both states, as well as an arrow indicating the change between State 1 (initial) and State 2 (final), and dashed arrows indicating the process represented as a 2-step process via intermediate State 0.