Unbalanced Flow

[cgeneroso]

Hi,

I am designing a solar chimney and have it placed over a small air space. When I try to run microflo, I get an unbalanced flow error with inflow showing 0 and outflow showing -143.22. When I look at the MacroFlo Arrows in VistaPro, I can see that I am getting an equal inflow and outflow. I would assume then that my issue is in exporting and importing the boundary data or has something to do with the intake opening as on just one occasion I have managed to resolve the issue by moving this opening to another surface. If it helps, I only started receiving this error when I introduced the small air space to the chimney and started modeling it in SketchUp. I have tried both to connect the two in ModelIT and in creating a multi-zone space in MicroFlo to no change.

Any advice would be appreciated, thanks!

[harshadj]

Hi,

Check whether you have created a multi-zone space out of all spaces connected via holes. If two of the spaces are connected by opening other than a hole, then a multi-zone space is created but flow may not be balanced for every zone. Also check if you have accidently deleted any of the flow boundaries.

Cheers

[cgeneroso]

Thanks for the advice. I have made sure that spaces are connected via holes and I unfortunately still get the error.

I recently made another model in SketchUp using only a single space and am still having an unbalanced flow. I first ran microflo with the exterior openings closed. I then opened them, ran apache, exported the new boundary information, cleared the old boundaries and imported the new ones in microflo and then got the unbalanced flow error. I checked the Macroflo Arrows on VistaPro and can see that at any time, my total inflow and outflow are not exactly the same, but within 10 cfm of each other. Microflo is reporting a difference -740cfm. Do you think the issue is in the boundary information?

[harshadj]

Are you importing boundary conditions for each zone separately and then creating the multi-zone space? If so, then this is the reason for your flow imbalance.

Remedy is clear all imported boundaries from all zones, re-create the multi-zone space, create the multi-zone space boundaries and then import the boundary conditions only for the parent zone. The boundary conditions for the child zones are imported automatically and the flows are balanced along with it.

[cgeneroso]

I select all the connected zones in the output options in Apache and then take the steps you've describe, but unfortunately still have an unbalance.

[harshadj]

Hi,

You can submit your query to the support team to have a better look at the model here.

http://www.iesve.com/support/contact-support-team