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Re: [EnergyPlus_Support] Loop delta Temp
Loop delta T is only used when autosizing the plant loop flow rate. See the
PLANT SIZING object in 5ZoneAuto.idf
Mike
On 20 Jan 2005, at 11:56, zhen tian wrote:
>
> Hi, Mike:
>
> As you suggested, I checked the model "VAVSingleDuctReheatBaseboard.idf".
>
> But I found that the temperature of 6.67C is set for the chilled water supply
> temperature, not the loop DeltaT. Am I right?
>
> Could you tell me where can I set the chilled water and hot water loop DeltaT? I
> guess I can set these DeltaT in the field of Plant Loop by setting Maximum and
> Minimum loop temperature. But I found that in examples, these DeltaT is quite
> big. For chilled water loop, it is ranged from 1degree C to 98 degree C. Can I
> set a reasonable Delta T in this filed?
>
> Thanks a lot.
>
> Regards,
>
> Zhen
>
> "Michael J. Witte" <mjwitte@xxxxxxxx> wrote:
> The temperature rise across the loop will depend on how you have sized the flow
> rate vs. load in the coils. Many (all?) of the example files use a 6.67C loop
> DeltaT.
>
> Mike
>
>
> On 17 Jan 2005, at 17:17, zhen tian wrote:
>
> >
> > Hi, Mike:
> >
> > I changed the Pump cofficeints to "0, 1, 0, 0" and now the "HW PUMP OUTLET
> > NODE:System Node Temp[C](Hourly) " and the "CW PUMP OUTLET NODE:System Node
> > Temp[C](Hourly) " are kept at 93 degree C and 5C, and accords well to the set
> > temperatures.
> >
> > But I checked the CW SUPPLY INLET NODE TEMP and CW PUMP OULET NODE TEMP, I
> > still get some temperatures like these: "5, 5, 5.5, 10.9, 15.4..." which are
> > close to the set temperatures, are these temperatures sound normal?
> >
> > Thanks a lot.
> >
> > Regards,
> >
> > Zhen
> >
> >
> >
> > "Michael J. Witte" <mjwitte@xxxxxxxx> wrote:
> > If the pump power remains constant and the flow varies, low flows will get hot
> > because the energy must go somewhere. You either need to let the pump power
> > vary (linear power would use coefficients of 0,1,0,0) or use a constant speed
> > pump so the excess flow will go through the bypass.
> >
> > Mike
> >
> > On 14 Jan 2005, at 16:39, zhen tian wrote:
> >
> > >
> > > Hi, Mike:
> > >
> > > Thanks for you reply. I have checked the pump input. Actually, I do use
> > > variable flow pumps with constant pump power. But I cannot change rated
> > > pump power consumption to "autosize" as this will cause severe errors. I did
> > > not use any autosize function in my model. I have upload my model named "
> > > ICT-NoRC-zt.zip " to the yahoo group. Could you check it for me? Thanks a
> > > lot. The weather file is Calgary, Alberta.
> > >
> > > Regards,
> > >
> > > Zhen
> >
> >
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========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support
EnergyPlus-Support@xxxxxxxx
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