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RE: [EnergyPlus_Support] Chiller Branch Issue



 
 
Node,36,CHW LOOP SUPPLY PUMP OUTLET NODE,Water,3

Node,37,ICE TANK OUTLET,Water,0

Node,38,CHW LOOP SUPPLY SIDE BYPASS PIPE INLET NODE,Water,1

Node,39,CHW LOOP SUPPLY SIDE BYPASS PIPE OUTLET NODE,Water,1

Node,40,CHILLER CHW INLET NODE,Water,2
 
The above is part of the .bnd file.  The zero shows that ice tank outlet is not not connected to any other branch.  The line before it has 3 connections.  This means that the Ice tank is cannected to the pum instead of the chiller splitter node.
 
The loop is broken, therefore the chiller loop does not show in the SVG.  This is the reason why you are not getting any results.

The Ice tank should be moved to the supply outlet position as in the example file.  The example file has a 5 zone building.  The chiller feeds he DOAS section. 
 
changechillerandicestoragenodenameBioPCM-ICEstorage.idf  was used for the above run, using designDay only.
 
There is no need to ask for all the daily, monthly values in the .csv.  They will be in the report by default.
 
The important values to look at is whether the chiller will go down to -5°C to make the ice, and how it is used in the following hour.  The example charge the tank during off peak and dischrge immediately afterwards.  Therefore, one day simulation is sufficient to view the operation.
 
If you use different building and different weather condition, all you would see is the variation of the operating between 0°C and 7.5°C.  At that point the chiller will be operating again, but not charging, the setpoint is now between 7.5 and 12.5°C.
 
I do not normally look at the curves, because the equations need to be evaluated and plotted to visulize the relationship between the variables.
 
I will look at the DSC curves and comment later.  The important number is how much energy you can store in one stix.
 
The laten heat  219 Kg/Kj is not right.
 
EPlus simulation is design to calculate heat transfer.  It will be better to say that the stix you are holding is equivalent to a piece of  ICE three times the volume.  
 
How many stix can cool the room of a certain size for one hour, when the OD temperature is say 10°C higher. 
 
You can use EPlus to get the cooling load for the room.
 
If you wanted to design a PCM for use as a wall materil, it should work like opening a thermal insulated window.  Closed in Winter, and open in summer when the OD temperature is right.
In another word, works like the economizer using OD air.
 
I was not saying that you should not model the PCM material. 
 
Trying to change the building geometry without reason is waste of time.  The building load is included in the 5-zone examiple which uses DOAS VAV and reheat.  Changing 80 to 218 (if there are such numbers in the curve) would give you the desired result.  So why to write another IDF? 
 
You do not have to agree with me.   If you agree all the time, you may be learning the wrong thing. Dr. Li  

 
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: jcrossett@xxxxxxxxxxxxxxx
Date: Fri, 10 Aug 2012 17:30:47 -0700
Subject: Re: [EnergyPlus_Support] Chiller Branch Issue

 
Dr Li, 
Latent heat is 219 Kg/Kj, melting temperature would be within 3 degrees of freezing temperature- and could be any temp.
Attached are a few DSC curves I have, more testing is underway- I wonder how I might modify the charge and discharge curves of in the ice storage object to be similar to the DSC testing- any ideas? I disagree about the lack of a need to model this- I think this may be more complicated than many things- and like many things the client needs reassurance how well the product will work, and the designers need to know what works best.
I am surprised to hear you do not think there is a reason to model this- not sure how to respond without sounding insulting- lets just say I disagree.

FYI I am not noticing the desired effect from the use of this object yet. (it causes increase of energy currently) and I think I may have it set up wrong- I guess I will keep experimenting- at least I have a file that does not have a fatal crash- 


Jeremiah D. Crossett  | Senior Analyst  |  Phase Change Energy Solutions
120 E. Pritchard St.  | Asheboro, NC 27203  | Mobile 503-688-8951
 

  






On Fri, Aug 10, 2012 at 4:33 PM, YuanLu Li <yli006@xxxxxxxxxxx> wrote:
 


Can you make your stix freeze below 0.C and melt at 0°C, and what is the latent heat?

If you can, it is the characteristic of  ICE without water. 
Design of the stix characteristics do not need EPlus simulation, as the building demand is not involved.  All you need to know is how much cooling energy can be collected at night at the highest  minimum night temperature of that location.

If you run the example file all the node names are defined.  Your building equipment will be using the branches between demand splitter and demand mixer. 
 
These branches are where the chiller provides the cooling supply.  Therefore, the storage tank should appear as a pranch there for charging.
 
The supply side pump must be the first branch, therefore you cannot insert the tank before that.  The example uses the supply outlet pipe branch, making a two component branch.  This is the discharge side of the tank.
 
As far as the branch naming is concerned, I always advise my student to draw a block diagram of the branches as required by the EPlus ordering.  The inlet node of a branch should have the outlet node name of the preceeding branch or component. This is indicated with an arror between the blocks.
 
The names of the supply and demand loop interface are those in the PlantLoop, Chilled Water Loop object.  These should be used for the connecting branch nodes.  In this case, there would be two arrow between the blocks.
 
These are general rules followed by the template expansion as well.

I have not look at your IDF yet.  I must understand the working of the  example file  first  before checking your IDF files.
 
 Dr. Li  

 

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: jcrossett@xxxxxxxxxxxxxxx
Date: Fri, 10 Aug 2012 14:00:10 -0700

Subject: Re: [EnergyPlus_Support] Chiller Branch Issue

 
Thanks Dr Li, 
This works in the example file- but the issue is the company sells these things- without modeling and I want to model them- it has to involve a real building or does not make since. 

The freezing temperature of our Phase Change Materials can be manufactured at any temperature from about -180 to +180 Celsius. 
Yes the idea would be to use this as a strategy to store night time cold for daytime cooling- if possible.. I so far have attempted to use chiller, DX and ideal loads- but have only been successful today for the first time with a chiller.  (thanks to the modeler who advised to change the node name)
Actually it would be interesting to be able to use this object with any cooling system, or even with just mechanical ventilation in a building without cooling.  

I thank you again for your response-

All the best- 


Jeremiah D. Crossett  | Senior Analyst  |  Phase Change Energy Solutions
120 E. Pritchard St.  | Asheboro, NC 27203  | Mobile 503-688-8951
 

  






On Fri, Aug 10, 2012 at 1:49 PM, YuanLu Li <yli006@xxxxxxxxxxx> wrote:
 


Run the example file:  5ZoneDetailedIceStorage.idf

Because this program connects the ice tank in seriese with the chiller loop, it does not need an extra loop for the ice tank.Glycol i sued to lower the temperature to -5°c when the chiller is on like to charge the ice tank.  The ice would form on the chiller coil in the ice tank.  When it is not charged, the ice melts, as the water temperature is raised to the normal chiller operation.

 
If you can fill the tank with ice, the storage capacity is increased 80 time.  Because the water ice transition has simple relation, it is rather simple to simulate.
 
What is the working temperature of the thermaSTIX.  Simply drop them into the ICE tank and set the freezing temperature.  Ice volume is calculated from the heat extracted from the tank. 
 
Actually, you simply increase the water tank size to that multiplied by the latent heat, the operating characteristic would be similar.   Cool the water to say 1°C during idle time and run the chiller at 1°C to 7°C with the compressor OFF, and then continue to run would be the same as freezing water into ICE and then melting it.
 
If the stix can freeze at 1°C  and melt at 1°C, it is behaving just like water/ice.  If you can freeze it at 1°C and melt at 30°C with a trigger, then it can be carrid around like the gel pack.
 
If it will freeze at 25°C and melt at the same or higher  temperature, then it  can be used to store night cooling
 
 Dr. Li  

 

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: jcrossett@xxxxxxxxxxxxxxx
Date: Fri, 10 Aug 2012 13:09:57 -0700
Subject: [EnergyPlus_Support] Chiller Branch Issue


 
I finally seem to have gotten the ice storage object to work but now it says my chiller is missing- When attempting to re-connect the chiller in any logical way I can think of I get fatal errors saying that I have duplicate node names. I put the day into this yesterday, read documentation and ran experiments and seem to have not gotten the detailed ice storage object to work- but in the process have apparently disconnected my chiller.  Can anyone help? Dr Li, your previous advise was over complicated I see not reason to make a refrigerated room when the goal is to cold charge a PCM in the night to use it in the day to pre-cool input for a chiller for a non refrigerated space. 

 
** Severe  ** Plant Component Chiller:Electric:EIR called "CHILLER" was not found on any plant loops.
   **   ~~~   ** Looking for matching inlet Node="ICE TANK OUTLET".
   **  Fatal  ** InitElectricEIRChiller: Program terminated due to previous condition(s).
   ...Summary of Errors that led to program termination:
   ..... Reference severe error count=1
   ..... Last severe error=Plant Component Chiller:Electric:EIR called "CHILLER" was not found on any plant loops.

  This project in particular is to use BioPCM Thermastix, (see image below) in a container to absorb cold and use it for chiller pre-cooling- basically as a replacement for ice in an ice storage type setup- seems perfect for Energy Plus Ice Storage Detailed object as it allows the "ice" to melt at a user specified temperature, and as manufactures we can make our PCM-ICE to melt at any temperature-- but the question is what temperature and how much to use, both questions it would be great if Energy Plus could answer- if only I could get the object to work.. I have been trying on and off for days- so any help would be appreciated. 





Jeremiah D. Crossett  | Senior Analyst  |  Phase Change Energy Solutions
120 E. Pritchard St.  | Asheboro, NC 27203  | Mobile 503-688-8951
 

  














































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