Re:RE: [EnergyPlus_Support] multi-primary pumps+secondary pump

Dear Dr. Li,

I think you mis-understand my situation.

I'm not trying to simulate the stand by chiller. I wonder how to simulate the chilled water pump for EACH chiller (The condenser side has no problem). I now have two chillers. Sometimes only one chiller is used and sometimes both are used. So according to the 90.1, each chiller should have a chilled water pump, right?

In the last strategy, I put the pump on the chillers branch. I think it is legal because I learned it from an example called 5ZoneBranchSupplyPumps. But the error occurs. I suppose the error has to do with the secondary pump on the demand side. I don't know how to deal with it. Or it may has other solutions.

In my case, both primary and secondary pumps are needed, and the primary side should have two pumps for two chillers. This is what I want to solve.

PS: The primary/secondary system is a kind of chilled water system configuration. The primary pump supply water to the chiller in the supply side, and the secondary pump supply water to the end users in the demand side. It could be considered as an energy conservation measure.

Thanks!

Han Xing

At 2011-10-29 19:50:35,"YuanLu Li" <yli006@xxxxxxxxxxx> wrote:

See comments below.

Dr. Li

To: energyplus_support@xxxxxxxxxxxxxxx
From: foolishstar@xxxxxxx
Date: Sat, 29 Oct 2011 19:31:30 +0800
Subject: [EnergyPlus_Support] multi-primary pumps+secondary pump

I'm now trying to simulate a pri/sec system with two primary pumps.
I tried three ways to do that but all failed.
first, I put the two pumps on the same branch, then, E+ told me that the pump had to be the first component in a branch.
In the same loop, not in the same branch. A pump had to be the first component in a loop, may be in a branch called a pipe.

In EPlus there is one configuration called "Common pipe" system. I do not know how this is defined. With this system, the pump should be on the demand side. In another word, the supply side may have two systems, and the output is connected to the demand side with one pump. The supply side pump may be optional.

I am not sure what you mean by primary and secondary system.

In EPlus there is not need to model the stand-by equipment. Is it what the guideline wanted?

Second, I tried to use two separate primary pump branches (two inlet branches), and the plant loop only has one plant side inlet node, so I set two plant loops, but E+ said that the demand side node name cannot be the same.
Last, I put the two primary pumps on the chiller branch, and the secondary pump on a separate branch. But the error occured showing as follows:
** Severe ** Current version does not support Loop pumps and branch pumps together
** ~~~ ** Occurs in loop CHW LOOP

The ASHRAE 90.1 requires that "each chiller shall be modeled with separate condenser water and chilled water pumps interlocked to operate with the associated ". Is it correct that I take it as each chiller should have one separate condenser water pump and one separate chilled water pump? Correct.
I read this as one pump in the chilled water loop and one pump in the condenser water loop. When the chiller stops both pump must respond with its associated algorithm, such as delay in the condenser loop, until the coild temperature is low.

If you must have one condenser loop per chiller loop, it has to be simulated that way.

If the two chillers are operating in the stendby mode, I do not think you need to simulate with two chillers.

Thanks!

Han Xing

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