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Re: [EnergyPlus_Support] PAU problems
1) You should use Set Point Manager:Single Zone Heating and Set Point
Manager:Single Zone Cooling to control the coils. You should also
account for fan heat using a Set Point Manager:Mixed Air object for each
coil. Place the Single Zone Heating set point at the outlet of the
system, then use the Mixed Air manager to account for fan heat and place
the set point at the heating coil outlet node. For the cooling coil,
place the Single Zone Cooling set point AT SOME OTHER NODE so you don't
overwrite the previous set points, and the use another Mixed Air manager
to account for fan heat and place the set point at the cooling coil
outlet node.
2) I do not have enough information to answer this question. What
objects are in the Air Primary Loop? Report the node volumetric flow
rates at each outside air mixer node (there's 4 of them) so you can
investigate this further.
beyangj wrote:
>
> Dear all,
>
> When I model the Primary Air Unit, from outside to inside, the
> equipments include: Outside Air Mixer, Cooling coil -
> Coil:Water:Cooling, Heating coil - Coil:Water:SimpleHeating,
> Fan:Simple:VariableVolume. There should be no return air for this system.
>
> There are some problems about this system,
>
> 1. Central cooling design supply temperature is 14℃, Central heating
> design supply temperature is 16℃. When the schedule for heating coil
> and cooling coil both are available, the cooling coil and heating coil
> work together. Even when the served zones need cooling only, the
> heating coil also work. The outlet temperature of the cooling coil is
> 13.19℃, the inlet temperature of the heating coil is
> 15.19℃, and the
> supply fan outlet temperature is 16℃. I wonder whether the heating
> coil can stop working for the hours need cooling only, especially in
> winter. In the winter, there need cooling for some hours, but need
> heating for some other hours, not sure about the exact hours.
>
> 2. I define the outside air method as flow/person. The person is
> variable at different hours. The PAU is expected to provide the
> variable fresh air with the variable fan, but the PAU supply air flow
> rate is constant, the PAU outside air inlet flow rate is not constant.
> The PAU Outside air mixer outlet flow rate is equal to the PAU outside
> air inlet flow rate for some working hours, but PAU Outside air mixer
> outlet flow rate is greater than the PAU outside air inlet flow for
> some hours, which may be caused by recirculation of return air, I
> think. What make this difference? The PAU supply air flow can be
> variable and always equal to the PAU outside air inlet flow rate?
>
> I appreciate your help.
>
> Jia
>
>
--
Richard A. Raustad
Senior Research Engineer
Florida Solar Energy Center
University of Central Florida
1679 Clearlake Road
Cocoa, FL 32922-5703
Phone: (321) 638-1454
Fax: (321) 638-1439 or 1010
Visit our web site at: http://www.fsec.ucf.edu
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