Re: [EnergyPlus_Support] About condenser pump / airflow window

["Michael J. Witte" <mjwitte@xxxxxxxx>]

1.  Check the order of the branches in the BRANCH LIST objects for all of the 
plant loops.  They must be in flow order, first the inlet branch, then the 
parallel branch(es), then the exit branch.  This may be the reason for the flow 
errors.

2.  EnergyPlus should be able to size multiple condenser loops.  Please send 
the idf file which crashed as a zipped attachment to energyplus-
support@xxxxxxxx or upload it to the files area in the yahoo group.

3.  The airflow windows in the "AirflowWindowsAndBetweenGlassBlinds" example 
file have airflow from inside the zone, through the window, and then exhausted 
to the outside.  The example file is structured  so that there are pairs of 
equivalent windows, one with airflow, and one without (see comments at top of 
example file).  Looking at windows "ZN001:WALL001:WIN001" and 
"ZN001:WALL001:WIN002", compare the Surface Inside Temperature and the Window 
Heat Loss.  Win002 which has airflow betwee the panes has a warmer surface 
temperature and less heat loss from the zone, and the air which exits the 
window is colder than the air that entered the window.  The example neglects to 
model the incoming fresh air required to supply the airflow leaving through the 
windows.  EnergyPlus will not balance the airflow from the window with other 
air flows in the simulation.  It is up to the user to supply this air with the 
HVAC system.  In this example, the HVAC system is PURCHASED AIR, and the 
outside air flow has been left out.  However, if the same quantity of outside 
air is delivered to the zone with and without airflow in the windows, the 
result will be the same.  Exhausting air through the window reduces the heating 
load, because the air which is dumped outside warms the window (reducing heat 
loss from the zone), and the air which is dumped is cooler than it would be if 
it were dumped directly to the outside.

Mike


On 26 Nov 2004, at 3:00, ekwtsang wrote:

> 
> 
> Dear all,
>      I am simulating a chilled water plant with 4nos 930TR water 
> cooled chillers and 1no 400TR chiller.
>      In Condenser plant, first i used a single condenser plant with 
> 4 "larger capacity" cooling tower and 1 "Smaller capacity" Cooling 
> tower to serve the chiller water plant. It is found that EnergyPlus 
> always says condenser flow for Chiller XX is 0 and terminated. This 
> kind of issue which i have never met before (I usually simulate the 
> plant with same capacity chillers).
>      So i change the operation scheme (lower the upper limit i.e. 
> start the next (a larger capacity) equipment list). It can solve the 
> above problem. But the other issue occurred, the program said that 
> the water flowrate in and out demand loop does not match. Even i have 
> set a bypass pipe, it still cannot solve this problem.
>      Lastly, i try to set 5 condenser loops to serve this single 
> chiller plant(each condenser loop for a single chiller), but the 
> program crash after autosizing the second condenser water pump.
>      To this end, i want to ask is it only allow 1 single condenser 
> plant to serve a chiller plant loop. Second, how to solve the problem 
> about flowrate of condenser loop.
> 
>      The other thing is to continue the problem about airflow window. 
> I have used the example 
> file "AirflowWindowsAndBetweenGlassBlinds.idf", it is found that the 
> energy extracted by the airflow window is negetive under winter 
> design day condition by changing the air flowrate in airflow window 
> to 0. It is found that the plant heating capacity increased and the 
> zone sensible heat loss increase. But the when summing up the heat 
> extracted through airflow window and window heat loss, the total heat 
> loss for the one with airflow is large. I still consider it does not 
> make sense or can anyone suggest me how to read it.
> 
> Regards,
> Ernest Tsang
> 
> 
> 
> 
> 
> 
> 
> 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.
> 
> Yahoo! Groups Links
> 
> 
> 
> 
> 
> 
> 
> 
> 



========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support      
EnergyPlus-Support@xxxxxxxx




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