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Re: [EnergyPlus_Support] Detailed ICE storage - for PCMs? Nodes & curves question

Most of the time the annual are sufficient.  The ASHRAE design conditions also include the coldest and hottest months -- and it isn't necessarily January and July.  In the attached example of annual design conditions, it's February and August.  But as the Fundamentals describes there are times when you want to base your sizing on humidity or even wind speed.

On Sun, Jul 22, 2012 at 2:59 PM, YuanLu Li <yli006@xxxxxxxxxxx> wrote:

For para (2)
The reason why there are so many DesignDay object example in the .ddy is that the moisture in the atmosphere is expressed, in wet-bulb, relative humidity %,humidity ratio, entropy.  There are only three statistical classes, namely, 0.4%, 1% and 2%.

I always use the 0.4% (99.6%) with WBM wet-bulb at maximum dry-bulb temperature.
The four dates for the four seasons are the longest, shortest, and the equinox.  Skyclearance i 1.0 for Winter when doing zone window beam studies. 
Jan 17 for Winter designday was chosen, because ODT average is not the lowest on the shortest day of the year.  The extreme day is usually in August for Summer.
The use of TMY was to remove the extreme cases.  Extreme weather week is different for different locatons and do not have known characteristics.  In fact, I did most of the verification of IDF with no weather files.
ASHRAE prepare the IWEC and .ddy make use of the information and statistical data from there.
With the new DesignDay object format and the WBM, I can use a swinging thermometer pair to get the two dry and wet values easily at any time.

 Dr. Li  


To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: jeremiah@xxxxxxxxxxxxxxxxxxxxxx
Date: Sat, 21 Jul 2012 11:49:06 -0700
Subject: Re: [EnergyPlus_Support] Detailed ICE storage - for PCMs? Nodes & curves question

Dr. Li

  1. I realized that GJ is Gigi joules shortly after the post when I switched to IP units and noticed the conversion to ton/hr- I was thrown off initially by the capacity concept, as I was looking for a tank size for gallons of water/ice, but have not found any reference to such a tank. I am now guessing that the GJ/Tonhr is the tank capacity- and that water must have a specific J/Btu of storage capacity. The Pure PCM materiel I am experimenting with is rated in Btu per pound, so I think could just specify the amount of Btu/J capacity of the PCM for this item. (If I where using water/Ice I suppose I would have to find the thermal capacity for the total tank amount but not sure)
  2. I have heard mixed messages about design day objects- for instance I have been told that all design day objects should be ran to produce accurate sizing by Linda & Drew, but told by Paulo the same as you say of only two needed. For using two I wonder what is the best way to choose the correct design days, and for some time thought it made more since to use Weather file:extreme summer week/Weather file:extreme winter week so that I could run the same building at many locations during parametric runs and so I did not have to make arbitrary choices of Design Days. Lately I have just been running files with all Design Days to be on the safe side.  I guess ASHRAE standards would be a good place for me to research for the best day type to choose/use. (your advise on this was appreciated)
  3. Research Goal:  I want to model the thermal energy storage functions of Pure PCM's, the current PCM modeling capabilities of e+ seem to be geared towards PCM's impregnated within other materials, and I want to check the difference in using them as a energy storage vessel, as well as test if it would be possible to use them in both ways simultaneously. I have seen empirical data showing benefits that exceed the benefits modeled with the current finite difference approach, so am experimenting to see if I can use the ice storage detailed object to more accurately depict the full benefits of pure phase change materials. The materials I am doing experimentation with can be viewed here: https://docs.google.com/spreadsheet/ccc?key=0Ag7cD5ZV9QwRdHlCSWVfWWV2WG5rQjdaN0dLTGlab2c
  4. I need to read the IO, as I guess I do not understand the Branch objects very well (I am spoiled in my use of design builder or HVAC templates so have not created a HVAC system line by line, nor have I edited branch objects before but now am dedicated to learn how this works) Are you saying that the placement of the object in the branch needs to be in a specific order position? I thought order position was not important and that the node connections where all that mattered. 
  5. I read the IO on ice storage and it seems that the chiller is used to charge ICE STORAGE, but I am looking to use a material with a melt temp in the 20-30C range so would want to charge the PCM/ICE with zone or possibly outdoor air, and am not sure if this is possible.
  6. I did not think of the refrigerated room experiment, and will have to research this in the IO and give it a try.

Part of the reason I am interested in this object is the difference in real world results/my hand calculations of PCM thermal energy storage potential and Energy Plus modeled results. My hand calc can be viewed/experimented with here:https://docs.google.com/spreadsheet/ccc?key=0Ag7cD5ZV9QwRdFJ1X0JpT1hOcEVMTk5fSlJDZXU4SHc

Thank you much for your response- I did not think anyone was goung to respond to this thread-

Kind regards-

On Sat, Jul 21, 2012 at 10:50 AM, YuanLu Li <yli006@xxxxxxxxxxx> wrote:

I have tried running your IDF, but do not know what you are trying to do.
GJ  is GigaJoules.
I do not know why you have so many designDay objects.  Only two are needed for sizing.  Four, if you are trying the four season solar beam study, and/or the transistion operation of the HVAC system..
Where do you intend to insert the storage tank?  The pipe object itself is not in the correct order postion of the IDF, therefore the branch was not recognized and flagged as a severe error.
If you want to discharge the tank load in a zone, then it should be declared as a zone equipment, or a tank placed in a zone.
I do not know how you can charge an ICE STORAGE TANK.  Is it a new object available in EPlus?  This is the first time I come across the ThermalStorage:Ice:Detailed.  I shall try to look it up in the ref. manuals.
You should use a refrigerated room and control its temperature for the experiment.  The PCM may be installed as the walls of the centrol zone with the four other peripheral zones as in the 5-zone building as controlled zones.
Without the ice strage branch, the IDF run was sucessfull.
 Dr. Li  


To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: jeremiah@xxxxxxxxxxxxxxxxxxxxxx
Date: Wed, 18 Jul 2012 20:20:22 -0700
Subject: [EnergyPlus_Support] Detailed ICE storage - for PCMs? Nodes & curves question

I am attempting to experiment with the detailed Ice storage object, as I noticed it has "freezing temperature of storage medium" rather than assuming freezing temp for water of 0C/32F. I added the objects from the example file to to a model I have been working on and attempted to connect the nodes, but when trying to run E+ crashes. Also I was thinking to use data from DSC tests of PCM for the charge and discharge curves, but am not sure how to approach it. (I am guessing 1=solid and 0= melt, but am unsure), also I wanted to use the thickness of PCM for the volume of the storage tank, but am unsure about the GJ, what unit would this be? Any advise would be great, and thanks in advance- 

Below is the copy paste's from the IDF..

Name Ice Tank
Availability Schedule Name ON
Capacity 0.5
Inlet Node Name Ice Tank Inlet Node
Outlet Node Name Ice Tank Outlet Node
Discharging Curve Object Type QuadraticLinear
Discharging Curve Name DischargeCurve
Charging Curve Object Type QuadraticLinear
Charging Curve Name ChargeCurve
Timestep of the Curve Data 1
Parasitic Electric Load During Discharging 0.0001
Parasitic Electric Load During Charging 0.0002
Tank Loss Coefficient 0.0003
Freezing Temperature of Storage Medium 23
Name DischargeCurve ChargeCurve
Coefficient1 Constant 0 0
Coefficient2 x 0.09 0.09
Coefficient3 x**2 -0.15 -0.15
Coefficient4 y 0.612 0.612
Coefficient5 x*y -0.324 -0.324
Coefficient6 x**2*y -0.216 -0.216
Minimum Value of x 0 0
Maximum Value of x 1 1
Minimum Value of y 0 0
Maximum Value of y 9.9 9.9
Minimum Curve Output
Name Cooling Supply Outlet
Maximum Flow Rate 0
Pressure Drop Curve Name
Component 1 Object Type ThermalStorage:Ice:Detailed
Component 1 Name Ice Tank
Component 1 Inlet Node Name Ice Tank Inlet Node
Component 1 Outlet Node Name Ice Tank Outlet Node
Component 1 Branch Control Type PASSIVE
Component 2 Object Type Pipe:Adiabatic
Component 2 Name Supply Side Outlet Pipe
Component 2 Inlet Node Name Ice Tank Outlet Node
Component 2 Outlet Node Name CW Supply Outlet Node
Component 2 Branch Control Type PASSIVE
Component 3 Object Type
Component 3 Name
Component 3 Inlet Node Name

Jeremiah D. Crossett
CleanTech Analytics

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