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RE: [EnergyPlus_Support] Fancoil total cooling power rate & total water cooling coil power rate
The dehumidification for the simple coil is very simple. You set the
leaving RH value for the coil outlet in the input for the simple coil. The
coil will dehumidify if the conditions are above that RH value.
Thanks Richard Liesen
At 08:51 AM 7/18/2003, you wrote:
>Thanks Richard,
>
>I followed your advised and checked the air enthalpies of all the nodes
>involved. Then I realized that the fancoil cooling power rates refer to the
>effect of the fancoil on the controlled zone. On the other side, the cooling
>coil power rates refer to the energy balance inside the fancoil. As I was
>working on an open loop system, there is no relation between this variables.
>
>Finally, I didn't find any documentation about how dehumidification is
>managed in a simple cooling coil. I would appreciate if anybody could tell
>me.
>
>Thanks in advance,
>
>
> -----Mensaje original-----
>De: Richard J. Liesen [mailto:rliesen@xxxxxxxx]
>Enviado el: miércoles, 16 de julio de 2003 18:55
>Para: EnergyPlus_Support@xxxxxxxxxxxxxxx; EnergyPlus_Support@yahoogroups.
>com
>Asunto: Re: [EnergyPlus_Support] Fancoil total cooling power rate & total
>water cooling coil power rate
>
>
> Miguel,
> The first thing you need to do is take one of your Fan Coil units and set
> the Maximum Outside Air = 0.0 and then look at the reports. When you do
> this then you will see exactly what you expect in the reports, ie. Total >
> Sensible, and Total Water Coil Cooling Rate = Fan Coil Total Cooling Rate
>+
> Fan Power. After you are confident that the variables are reporting what
> you expect then add the mixed air stream to the results. Total Q across
> the unit is just the enthalpy change and the sensible Q across the unit is
> the change in enthalpy at a constant inlet humidity ratio.
>
> Total Enthalpy
> QTotUnitOut = AirMassFlow * (Node(OutletNode)%Enthalpy -
> Node(InletNode)%Enthalpy)
>
> Sensible Change
> QUnitOut = AirMassFlow *
> (PsyHTW(Node(OutletNode)%Temp,Node(InletNode)%HumRat) &
> -
> PsyHTW(Node(InletNode)%Temp,Node(InletNode)%HumRat))
>
> Remember that these variables are looking across the entire unit including
> the mixed air contributions.
>
> For the example case that I was looking at and when you look at and report
> the Temperature and Humidity Ratio at each node location, ie. FanCoil1
> # Description
> 5, ZONE1FANCOILAIRINLETNODE
> 56, ZONE1FANCOILEXHNODE
> 1, ZONE1FANCOILOAINNODE
> 59, ZONE1FANCOILOAMIXEROUTLETNODE
> 62, ZONE1FANCOILFANOUTLETNODE
> 65, ZONE1FANCOILCCOUTLETNODE
> 4, ZONE1FANCOILAIROUTLETNODE
>
> You will find that the Latent Load added through the mixed air is greater
> than what is extracted by the Cooling Coil.
>
>
> Thanks
> Dr. Richard J. Liesen Ph.D. M.E.
> Associate Director, Building Systems Laboratory
> Department of Mechanical and Industrial Engineering
> University of Illinois at Urbana-Champaign
> * * * * * * * * * * * * * * * * * * * * * * *
>
>
>
> t 02:54 PM 7/16/2003, Miguel Angel Pascual wrote:
> >hello,
> >
> >I'm running a simulation with a FAN COIL UNIT:4 PIPE with a
> >COIL:Water:SimpleCooling object and I have noticed an important
>difference
> >between the variables "Fancoil total cooling power rate" and "total
>water
> >cooling coil power rate". I thought that both variables should be very
> >similar, but the difference is much bigger than the electric power fan.
> >
> >I am taking 100% outside air to the fancoil, and under condensing
>conditions
> >"Fancoil total cooling power rate" and "Fancoil sensible cooling power
>rate"
> >are almost the same. In some cases, the total cooling power rate was
>smaller
> >than the sensible fancoil variables.
> >
> >Does anybody know what is going on?
> >
> >
> >Miguel Ángel Pascual
> >Dtor. Ingeniería
> >MIYABI
> >mapascual@xxxxxxxxxxxx
> >948 203 644
> >
> >
> >
> >[Non-text portions of this message have been removed]
> >
> >
> >
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