If you want to ignore the warnings and run HeatExchanger:AirToAir:SensibleAndLatent outside of the approved range, then it is important to input the same effectiveness values at 75% and 100% flow. Those values create a linear model for effectiveness vs. flow and it can easily be the case that out-of-range flows produce nonsense effectiveness values. You need a flat, or at least very shallow, slope for that linear model and setting the effectiveness values to be the same at 75% and 100% does that.
From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Jean marais
Sent: Tuesday, November 01, 2011 2:21 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] Re: Demand Ventilation Control and Enthalpy Wheel
So what happens currently when the bounds are exceeded? Does the wheel turn off? I could live with that.
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Richard Raustad <RRaustad@...> wrote:
>
> This issue has come up many times in the past. The manufacturer cannot
> guaranteethe ratings of the HX when the flow rate ratio is <50% or >130%
> of design. It's as simple as that. And there was no guidance of what to
> do inside the model when the air flow ratio was out of bounds since even
> the manufacturer could not tell us. If you want to use this HX model,
> keep the air flow ratio within the boundaries of where the model is
> valid. Otherwise, change to a flat plate HX (no latent heat transfer).
>
> On 11/1/2011 4:04 PM, Jean marais wrote:
> >
> > Had exactly the same issue doing exactly the same thing for the summer
> > case. I don't know any way to suppress warnings. Obviously, the amount
> > of heat exchange at the enthalpy wheel reduces to very small amounts
> > when the flow from exhaust is <50% the supply side. It seemed as if
> > the wheel stopped working, when I watched the outputs, but I actually
> > have no idea how the object is programmed to react in these
> > conditions. PS in the project I was simulating, an evapourative cooler
> > was cooling the
Primary EnergyPlus support is found at:
http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx
The primary EnergyPlus web site is found at:
http://www.energyplus.gov
The group web site is:
http://groups.yahoo.com/group/EnergyPlus_Support/
Attachments are currently allowed but be mindful that not everyone has a high speed connection. Limit attachments to small files.
EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
Change settings via the Web (Yahoo! ID required)
Change settings via email: Switch delivery to Daily Digest | Switch to Fully Featured
Visit Your Group | Yahoo! Groups Terms of Use | Unsubscribe
__,_._,___