Re: [EnergyPlus_Support] Re: COMSI AIR FLOW:OPENING=>Discharge coefficient ?

["Joe Huang" <yjhuang@xxxxxxx>]

Ming,

My responses follow.

Joe
----- Original Message -----
From: "waspoorboy" <mingsbox@xxxxxxxxxxxxxx>
To: <EnergyPlus_Support@xxxxxxxxxxxxxxx>
Sent: Monday, December 08, 2003 10:53 PM
Subject: [EnergyPlus_Support] Re: COMSI AIR FLOW:OPENING=>Discharge
coefficient ?


> Joe,
>
> Thanks for your explanation.
>
> For crack, Q=Cp*(delta P)^n
>
> For opening, Q= Cd*A* f(delta P)
>
> 1.The airflow calculation for LVO is some complicated function in
> COMIS, much more complicated than crack flow. (Y/N)

Yes.

> 2.The calculation algorithm of LVO is not explained in COMIS 3.0 user
> guide, is there any manuals or publications that talk about it ?

The mathematics is explained in COMIS Fundamentals, edited by H. Feustel and
A. Rayner-Hooson, LBL-28560, Lawrence Berkeley Laboratory, May 1990.  I've
scanned in and attached a few pages describing the solution for air flow
through large openings. Please contact Brian Smith at BVSmith@xxxxxxx if you
want a copy of COMIS Fundamentals.
>
> 3.If Cd is specified by user (not zero), then COMIS will use it and
> not determine the Cd from the other input parameters. (Y/N)

Yes.

> 4.For EnergyPlus/COMIS to determine Cd itself, the user specify all
> Cd to zero for all opening factors. (I mean does this work in
> EnergyPlus/COMIS as in COMIS 3.0) (Y/N)

Yes.

> 5.Is it recommended to let COMIS determine Cd itself ? (Y/N)

Yes, unless you have a good value for Cd.

> 6.E+ I/O ref manual p.245 says Cd should be 0.0 ~ 1.0,
> but COMIS 3.0 manual p.62 says Cd can be up to ~ 1.5,
> does it work in E+ when Cd > 1.0 ? (Y/N)

Yes, I think so, although I haven't verified that.
>
> 7.COMIS AIR FLOW:Opening,
> W_Window, !- Name
> .0001,    !- Air Mass Flow Coeff Window or Door Is Closed
>
> some combinations of Air Mass Flow Coeff cause error message
> in E+/COMIS:
> **Fatal** Error in the ventilation part! MATRIX SINGULAR FOR ZONE #6
> Is there any solutions ?
>
> Thanks again,
> Ming
>
>
>
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