[Bldg-sim] Secondary variable pump modeling

[Malherek, Elyse]

That warning is stating that you don’t have any control scheme set up to manage the water temperature in the chilled water loop.

You’ll have to use a SetpointManager:Scheduled (or some other setpoint manager if you don’t have a single setpoint control).  You’ll need to reference which node you are referring to, but it should be either Plant Side Outlet Node (which sets the temperature of the mixed water leaving the chillers and chiller bypass) or the Demand Side Inlet (which sets the temperature of the water entering the coils).  I usually do the Plant Side Outlet Node.  You can check what the name of that node is in the PlantLoop object for the chilled water system; it will be the node name for the Plant Side Outlet Node Name parameter.  (In that example file I referenced, the setpoint node was Chilled Water Loop ChW Pri Supply Outlet)

In the SetpointManager:Scheduled object you will need to reference a schedule.  If you have a fixed temperature setpoint, the easiest schedule to use is the Schedule:Constant.  Remember that the value should be in degrees Celsius.

Hopefully that helps.

Regards,

Elyse Malherek
Applications Engineer
McQuay International
a member of DAIKIN group
763.553.5379 (Office)
elyse.malherek at mcquay.com<mailto:elyse.malherek at mcquay.com>
________________________________
From: 韩星 [mailto:foolishstar at 163.com]
Sent: Wednesday, October 26, 2011 4:14 AM
To: Malherek, Elyse
Cc: Jean marais; bldg
Subject: Re:RE: [Bldg-sim] Secondary variable pump modeling

Dear Malherek,

Thank you for your advice! It really helped me!
But I still have some questions.
When I use the common pile in the "Plant Loop", the simulation could run. But when I tried to use the "Two-way common pile" as you indicated, errors occur as follows.

   ** Severe  ** While using a two way common pipe there must be a set point in addition to the Plant Supply Outlet node.
   **   ~~~   ** Currently neither plant demand inlet nor plant supply inlet have setpoints.
   **   ~~~   ** Select one of the two nodes and rerun the simulation.
   **   ~~~   ** Occurs for:  PlantLoop=CHW LOOP

Can you please give me a hint?

Thanks!

At 2011-10-25 22:50:54,"Malherek, Elyse" <elyse.malherek at mcquay.com<mailto:elyse.malherek at mcquay.com>> wrote:

You can look at the EnergyPlus example file called 5ZoneVAV-Pri-SecLoop.idf as a guide for creating a primary-secondary chilled water flow configuration in EnergyPlus.

Basically, you just have to have two pumps in the chilled water plant loop: a Pump:VariableSpeed object to represent the secondary loop and a Pump:ConstantSpeed object to represent the primary loop.  And then in the chilled water PlantLoop object, change the Common Pipe Simulation parameter from blank to “TwoWayCommonPipe”

You may want to run the example file and look at the .svg output file to see how the plant is arranged and how the node names should match between the various EnergyPlus objects.

Use the EngineeringReference document (from the help menu) and search the document for Primary-Secondary to find the section that explains how primary-secondary loops are implemented and controlled in EnergyPlus.

Elyse Malherek
Applications Engineer
McQuay International
a member of DAIKIN group
763.553.5379 (Office)
elyse.malherek at mcquay.com<mailto:elyse.malherek at mcquay.com>
________________________________
From: bldg-sim-bounces at lists.onebuilding.org<mailto:bldg-sim-bounces at lists.onebuilding.org> [mailto:bldg-sim-bounces at lists.onebuilding.org<mailto:bldg-sim-bounces at lists.onebuilding.org>] On Behalf Of ??
Sent: Tuesday, October 25, 2011 1:18 AM
To: 'bldg'
Subject: [Bldg-sim] Secondary variable pump modeling

in the modeling of pump systems, according to 90.1, it should be primary/secondary systems with VSD on the secondary pumping loop.
I wonder how to model this in E+.
Besides, how to know the four coefficients of the variable speed pump? in E+, it is said that the variable speed pump model is described in the ASHRAE secondary HVAC toolkit, but I don't have it.
Can anybody give me a hint?
Thanks!







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