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[EnergyPlus_Support] Re: About temperature control



Thanks for your reply.I've downloaded the lastest version.

I have some more problems and expectation for your kind help.

1. At present,i'm studying the outside air economizer control.In 
i/o ,it said:"if the outside air temperature is greater than or equal 
to the mixed air temperature
set point, the outside air flow rate is set to the maximum; if the 
outside air temperature is less
than the mixed air temperature set point, the outside air controller 
will modulate the outside
air flow so that the mixed air temperature will match the mixed air 
set point temperature." 

 I can't understand this sentence.So i simulate the 5ZoneEngChill.idf 
for all year to study the result report.But i find,during system 
operative period,the mixed air node temp is nearly the same with the 
outside air temp,except at the first hour(at 8:00)mixed air temp is a 
little greater than outside air temp.During uncontrolled period,the 
temp is different from the outside air temp.The mixed temp setpoint 
is the VAV outlet setpoint subtract the fan temp rise.Now that the 
mixed air temp is just the outside air temp,then how does the 
economizer run?Does the temp comparision have significant meaning?
Probably,i understand it false.Could you explain the control method 
detailed for me?

2.For all year simulation,during seasonal period,for example in oct 
5,the outside air temp is high enough.But it is during heating 
period,although the heating coil did not work,the temp in zone rise 
straightly,sometimes reach 28¡æ.It is not comfortable.Can you give me 
a method to deal with such case?(Taking no account of other 
thing,such as energy waste.I just want to the zone be controlled well 
and gain the comfort report)

  Thanks in advance.
  pch


--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Fred Buhl <wfbuhl@...> 
wrote:
>
> The current EnergyPlus program should handle over cooling by VAV 
systems
> correctly (by turning on the reheat coils and reheating to the 
heating 
> setpoint).
> If you are using the current version of EnergyPlus, please upload 
your file.
> 
> In 5ZoneEngineChiller, the central heating coil is used all year 
(in the 
> current
> example file I am looking at). Confusingly, there is a schedule 
called 
> HeatingCoilAvailSched,
> but it is not used. The central heating coil uses the same 
availability 
> schedule as the
> reheat coils. The cooling coil appears to be scheduled off in the 
> winter, though it
> is on for the winter design day.
> 
> Make sure all your coils are scheduled on when you want them to be. 
Also 
> check the
> pump schedules. If the pump serving a coil is off, the coil won't 
> operate even if it
> is scheduled on.
> 
> Fred Buhl
> 
> hbn_pch wrote:
> > Hi,all
> > 	I¡¯ve create a model using Standard VAV system without 
> > outside 	air, hot water reheat coils,purchased cooling and 
heating. 
> > All equipment is autosized. Zone temp control is dual setpoint 
with 
> > deadband. Zone heating setpoint is 20¡æ,coolint setpoint is 
26¡æ.VAV 
> > supply air temp setpoint seasonal change is 13 ¡æ in summer and 
16¡æ 
> > in winter.
> > 	1.I simulate for all year and find that some days in summer 
> > are too cold(21¡æ~22¡æ).I check the VAV damper,it is in minimum 
air 
> > fraction.It seems that the supply air is too cold to control the 
zone 
> > to temp setpoint.Can VAV reheat coil heat the cold air to remain 
zone 
> > setpoint temperature?How to adjust this days to zone temperature?
I 
> > check the vav reheat coil,it is off.
> > 	2.I run the example 5ZoneEngChill.idf for all year.I found 
> > in some day,such as Apr 3,the main heating coil is on at 
sometime,but 
> > the main heating coil scheduled off .I¡¯m puzzled.Does it has a 
> > priority problem?On the other side,if in winter require 
> > cooling,system can turn on the cooling coil although it is 
scheduled 
> > off?
> > 	3.The design day are controlled well,but for all year,some 
> > days are controlled bad.At present I just want to control the 
zone to 
> > temperature setpoint and gain the corresponding thermal comfort. 
> > Taking no account of other.Does the VAV templet achieve aim?Can 
you 
> > recommend other HVAC system?
> >
> > 	Thanks in advance.
> >          pch
> >
> >
> >
> >
> > ------------------------------------
> >
> > 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 not allowed -- please post any files to the 
appropriate folder in the Files area of the Support Web Site.
> >
> > EnergyPlus Documentation is searchable.  Open EPlusMainMenu.pdf 
under the Documentation link and press the "search" button.
> > Yahoo! Groups Links
> >
> >
> >
> >
>



------------------------------------

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