Mechanical Ventilation

[Vera-MVD]

Hi everyone.

Some of you have seen my other discussion about using CFAST for an inert environment. While I am currently struggling with making manual changes to the source code to reflect the desired environment (especially a different initial pressure on the inside), I've decided to test the mechanical vent CFAST feature to set the sub ambient pressure inside my compartment. I have just a cube with 10m side (and 0.5m thick walls all around). 40C inside, 20C outside, 0% humidity. The wall-ceiling-floor material: I am just using the default CFAST numbers for now. The task is to get the pressure inside the cube to 100331Pa (relative pressure: -4 in w.g). Since, there is no inside pressure input parameter, I am starting with ambient pressure (at 40C) on the inside and using a mechanical vent (the setup is shown in the screenshot attached). I run first to see pressure profile and see when it drops to the target value. After that I added a time ramp for the mechanical vent turning it off the next second after the reaching the target. There are no other vents/opening in the cube. So, with the mechanical vent closed off, I was expecting to see the cube pressure staying at the same level after that, but it still continues to drop as if the vent was still ON. What drives the inside pressure at that point, why is it still dropping? What am I doing wrong?

Also, while testing the mech vent feature, I've noticed that the compressed output file (txt format) does not show the correct value for the vent area and the vent rate. It looks like it shows the rate instead of the area, and visa verse. I've opened one of the built in examples (User_Guide_example) just to double check and the numbers are flipped there as well. Another question here, how can I see the mech vent ramp in the compressed output file? It clearly has a place holder for that, but it is not filled with numbers. Is there a checkbox somewhere that needs to be checked for that? I am attaching a screenshot for this observation as well.

Thanks you in advance for any help with this and I am sorry if the questions are trivial, I am still trying to figure out how everything works, mostly by trial and error.

Vera