RE: [EnergyPlus_Support] How to model Primary and secondary both variable pumps in Chiller water systems

Andres,
there is a way to model variable flow in the condenser loop,using EMS.
I have done in the past but I dont have the files here now.
It is simply,set a condition to define the flow rate,I set a delta temperature of 5 degrees in the loop and then use EMS and define the flow rate of your variable pump.
I hope this help.
Ignacio Gomis

El 30/08/2013 20:45, "Griffith, Brent" <brent.griffith@xxxxxxxx> escribió:

Unfortunately the chiller models don?t really modulate their requests for condenser water flow. They always request the design flow rate through the condenser when running. So, unless the condenser loop serves a number of different machines that are staging on and off, there really isn?t a way to get varying flow rates. About all you can do is adjust the pump to be more efficient or have less static pressure to reduce energy use, just as a way of modeling.

From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of dante andres garcía meneses
Sent: Friday, August 30, 2013 12:35 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] How to model Primary and secondary both variable pumps in Chiller water systems

Thank you.
IUnfortunatly use E+ 7.1 versión (For sure I will try it later)

I have another question in my same energy model:

Water colled chiller is conected to a cooling tower with a variable pump.
I simulated variable condenser pump in the condenser loop, but the result is equal than if a had simulated a constant condenser pump.

I have a condenser plant and a variable pump, mi equipment is CoolingTower:VariableSpeed.

How should i model it to show savings with variable condenser pumps?

Thank you again.
2013/8/30 Griffith, Brent <brent.griffith@xxxxxxxx>

I would recommend *not* using the Common Pipe Simulation in the PlantLoop object. The relatively new HeatExchanger:FluidToFluid is able to reliably connect two separate plant loops together and can be controlled. With this heat exchanger you would have two separate Plant Loops, one for primary and one for secondary (or even multiple secondary loops). There are no limitations for variable speed pumps with this approach.

From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of andresdagm@xxxxxxxxx
Sent: Thursday, August 29, 2013 9:25 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] How to model Primary and secondary both variable pumps in Chiller water systems

Hi, all group, i need some help!

I got this warning when i try to simulate a Primary and secondary both variable pumps in Chiller water systems (The chiller incorporate VFD):

** Warning ** SetupCommonPipes: detected variable speed pump on supply inlet of TwoWayCommonPipe plant loop
   **   ~~~   ** Occurs on plant loop name = CHW LOOP
   **   ~~~   ** The common pipe model does not support varying the flow rate on the primary/supply side
   **   ~~~   ** The primary/supply side will operate as if constant speed, and the simulation continues.

It seems that Commonpipesimulation in Plant Loop doesn't simulate primary and secondary variable pumps.

There is any way to could model primary and secondary variable pumps??

Thank you,

Dante Garcia