Hi, Xin
I do not have the ASHRAE document so I do know how they define the primary and secondary system.
In EPlus, the two chillers on the same ChW loop is to save power. When the load is low, only one will be turned on. The PLR will be higher and more efficient. This is the large and small chiller example.
Is the chiller pump the condenser pump or the water pump? The chiller has the Dx coil in the ChW tank. The ChW use side has a water circulating pump.
The two pumps I mentioned below are for the two water loops. There is no water pump associated with a chiller itself. The pump is for the tank and water loop. Therefore there is no secondary pump. Two compressor pumps for two chillers.
==========================
In a modular compressor system, you can have more than one mechanical pump compressor to compress the coolant into one resourviour tank, running multple Dx coils in different AHU's. (Split units) The condesor coil can be common as there is only one coolant loop.
That was why I ask you to find the definition of the pri/sec system first.
==================
For the COP and EIR coefficients, I think you were using the formula from another software.
If the EPlus object has temperature and PLR specified, it should be a x,y equation.
There are some example curves and coefficients in the DataSet directory, chillers.idf .
===========
You can send me the IDF. If you use the template model, send the original IDF, not the expIDF.
If you have complicated building envelop, it is better to use a 3 or 5 zone building to save time. The load size is not important in trying out the IDF.
The IdealLoadsAirSystem always give you the best result. HVAC with real equipment always consumes more energy.
Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: foolishstar@xxxxxxx
Date: Sat, 29 Oct 2011 20:37:53 +0800
Subject: Re:RE: [EnergyPlus_Support] multi-primary pumps+secondary pump
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Primary EnergyPlus support is found at:
http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx
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 currently allowed but be mindful that not everyone has a high speed connection. Limit attachments to small files.
EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
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I do not have the ASHRAE document so I do know how they define the primary and secondary system.
In EPlus, the two chillers on the same ChW loop is to save power. When the load is low, only one will be turned on. The PLR will be higher and more efficient. This is the large and small chiller example.
Is the chiller pump the condenser pump or the water pump? The chiller has the Dx coil in the ChW tank. The ChW use side has a water circulating pump.
The two pumps I mentioned below are for the two water loops. There is no water pump associated with a chiller itself. The pump is for the tank and water loop. Therefore there is no secondary pump. Two compressor pumps for two chillers.
==========================
In a modular compressor system, you can have more than one mechanical pump compressor to compress the coolant into one resourviour tank, running multple Dx coils in different AHU's. (Split units) The condesor coil can be common as there is only one coolant loop.
That was why I ask you to find the definition of the pri/sec system first.
==================
For the COP and EIR coefficients, I think you were using the formula from another software.
If the EPlus object has temperature and PLR specified, it should be a x,y equation.
There are some example curves and coefficients in the DataSet directory, chillers.idf .
===========
You can send me the IDF. If you use the template model, send the original IDF, not the expIDF.
If you have complicated building envelop, it is better to use a 3 or 5 zone building to save time. The load size is not important in trying out the IDF.
The IdealLoadsAirSystem always give you the best result. HVAC with real equipment always consumes more energy.
Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: foolishstar@xxxxxxx
Date: Sat, 29 Oct 2011 20:37:53 +0800
Subject: Re:RE: [EnergyPlus_Support] multi-primary pumps+secondary pump
Dear Dr. Li,
At 2011-10-29 19:50:35,"YuanLu Li" <yli006@xxxxxxxxxxx> wrote:
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 LOOPThe 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
__._,_.___
Primary EnergyPlus support is found at:
http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx
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 currently allowed but be mindful that not everyone has a high speed connection. Limit attachments to small files.
EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
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