Hi, Mingmin
Actually the IDF will be more useful, as the output does not usually show what I wanted to see.
In real system, the ice tank should not be allowed to freeze solid. The ice is formed around the evaporating coil and may break off to float to the top of the tank. 0.5°C I think is the temperture of the tank water. -0.5°C is the water near the coil.
When the ODT is low, the tank water may reach 0.5°C directly from the chillor coil, therefore the pump is stopped. I shall try changing the ODT on the DesignDay object or the conductivity of the tank to observe the effect.
The output and efficiency of the chiller in your IDF is varying over a large range. This may due to the fact that your building VAV system is not properly designed yet., or the curves may be wrong.
So, I think that the tank going into the by-pass mode during ice making is normal. The cause has not been fully identified. Type 4 thermostat may play a part, as it may turn on night heating in Summer. This is why the buiding characteristic must be known before testing other plants.
Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: icesand@xxxxxxx
Date: Sat, 1 Dec 2012 21:45:23 +0800
Subject: Re: RE: [EnergyPlus_Support] Unstable control during thermal charging period with Ice storage tank.
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Primary EnergyPlus support is found at:
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The primary EnergyPlus web site is found at:
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The group web site is:
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Actually the IDF will be more useful, as the output does not usually show what I wanted to see.
In real system, the ice tank should not be allowed to freeze solid. The ice is formed around the evaporating coil and may break off to float to the top of the tank. 0.5°C I think is the temperture of the tank water. -0.5°C is the water near the coil.
When the ODT is low, the tank water may reach 0.5°C directly from the chillor coil, therefore the pump is stopped. I shall try changing the ODT on the DesignDay object or the conductivity of the tank to observe the effect.
The output and efficiency of the chiller in your IDF is varying over a large range. This may due to the fact that your building VAV system is not properly designed yet., or the curves may be wrong.
So, I think that the tank going into the by-pass mode during ice making is normal. The cause has not been fully identified. Type 4 thermostat may play a part, as it may turn on night heating in Summer. This is why the buiding characteristic must be known before testing other plants.
Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: icesand@xxxxxxx
Date: Sat, 1 Dec 2012 21:45:23 +0800
Subject: Re: RE: [EnergyPlus_Support] Unstable control during thermal charging period with Ice storage tank.

Dr. Li,
For your convenience, I have attached output results for both example and
my idf, the run period is set from 1st. July to 31 July. By the way, the
charging period is from 11 PM today to 6 AM next day.
Zuo Mingming
From: YuanLu Li
Date: 2012-12-01 21:05
Subject: RE: [EnergyPlus_Support] Unstable control during
thermal charging period with Ice storage tank.
I only ran your IF on Designday simulation.
The system seems to function normally. -5°C is the ice makeing period, 7 is the chiller minimum temperature, 0.5 °C is the ice cooling the plant water.
The system is schedule driven. You may change the schedule so that there is larter gap between the ice making period and the plant use period. Because the zone temperature and ODT were not displayed, I am not sure when the demand starts.
In EPlus simulation, it is important always to keep the demand in view. Then you can procede to analyse the system and plant performance.
I was displaying the result and did not see any oscillation between timesteps. This may be in the weather file run, as the operating range would be different. I have not done the annual simulation yet.
I shall let you know if I can see the oscillatng conditions.
Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: icesand@xxxxxxx
Date: Sat, 1 Dec 2012 20:32:47 +0800
Subject: Re: RE: [EnergyPlus_Support] Unstable control during thermal charging period with Ice storage tank.
The system seems to function normally. -5°C is the ice makeing period, 7 is the chiller minimum temperature, 0.5 °C is the ice cooling the plant water.
The system is schedule driven. You may change the schedule so that there is larter gap between the ice making period and the plant use period. Because the zone temperature and ODT were not displayed, I am not sure when the demand starts.
In EPlus simulation, it is important always to keep the demand in view. Then you can procede to analyse the system and plant performance.
I was displaying the result and did not see any oscillation between timesteps. This may be in the weather file run, as the operating range would be different. I have not done the annual simulation yet.
I shall let you know if I can see the oscillatng conditions.
Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: icesand@xxxxxxx
Date: Sat, 1 Dec 2012 20:32:47 +0800
Subject: Re: RE: [EnergyPlus_Support] Unstable control during thermal charging period with Ice storage tank.

Dr.Li,
Thank you first! I have ran the example model named
"IceStorage-Series-ChillerUpstream", it has the same problems as I did. Once you
turn the output interval from hourly to timestep, the same fluctuations showed
up for parameters such as
Detailed Ice Thermal Storage Mass Flow Rate and
chilled water loop temperatures during ice charging period, in my opinion, it is
due to the internal control algorithms and it will start and shut down the
system too frequently around the turnoff temperature which is set in the low
temp turn off availability manager. In addition, the chilled water flow rate
schedule is set to always unit one, which would also confuse me. If you set the
pump operation mode to Intermittent, no ice will be made in the night charging
period. You can have a try on the example files. Thank you again and I am
looking forward to your reply!
Zuo Mingming
From: YuanLu Li
Date: 2012-11-30 21:10
Subject: RE: [EnergyPlus_Support] Unstable control during
thermal charging period with Ice storage tank.
Have you ran the example file on Ice storage?
This example reduce the chiller temperture to -5°C when the chiller load is light or not required, so that ice can form on it..
In order to make ice the temperature of the coil in the storage tank has to be low. There are a number of steps mentioned in the example that described special requirement. There is dummy load during the ice making time, etc.
The ice is formed on the chiller coil in the storage tank, and the pump is in the water loop. What you are describing seems to be tying to make ice while the water loop is still active to provide buiding cooling.
I have not look at your IDF yet.
Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: icesand@xxxxxxx
Date: Fri, 30 Nov 2012 08:20:39 +0000
Subject: [EnergyPlus_Support] Unstable control during thermal charging period with Ice storage tank.
This example reduce the chiller temperture to -5°C when the chiller load is light or not required, so that ice can form on it..
In order to make ice the temperature of the coil in the storage tank has to be low. There are a number of steps mentioned in the example that described special requirement. There is dummy load during the ice making time, etc.
The ice is formed on the chiller coil in the storage tank, and the pump is in the water loop. What you are describing seems to be tying to make ice while the water loop is still active to provide buiding cooling.
I have not look at your IDF yet.
Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: icesand@xxxxxxx
Date: Fri, 30 Nov 2012 08:20:39 +0000
Subject: [EnergyPlus_Support] Unstable control during thermal charging period with Ice storage tank.
Hi all,
I have composed a model with ice storage tank, but supecious fluctuations of chilled water flow as well as charging performance are detected. The problems are as below:
1. the primary chilled water pump has to be set to continous mode, otherwise the ice tank will never have any charging energy.
2. once this pump is under continous mode, fluctuations of the node parameters come about. For example, chiller evaporator inlet temperature changes from 7C to -5C every timestep. The low temperature tunoff manager has been used in this model.
Would you please help me find the possible solutions? Thank you all in advance and the idf file named "Thermal energy storage Test" has been uploaded to the files of this group.
I have composed a model with ice storage tank, but supecious fluctuations of chilled water flow as well as charging performance are detected. The problems are as below:
1. the primary chilled water pump has to be set to continous mode, otherwise the ice tank will never have any charging energy.
2. once this pump is under continous mode, fluctuations of the node parameters come about. For example, chiller evaporator inlet temperature changes from 7C to -5C every timestep. The low temperature tunoff manager has been used in this model.
Would you please help me find the possible solutions? Thank you all in advance and the idf file named "Thermal energy storage Test" has been uploaded to the files of this group.
__._,_.___
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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