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How to stop chiller from running while thermal energy storage still has capacity?

asked 2019-02-26 11:15:08 -0500

mldichter gravatar image

I'm looking into the IceStorage-Series-ChillerDownstream.idf energyplus example file which uses a ThermalStorage:Ice:Detailed object and other controlling objects to use thermal energy storage for cooling.

In particular, I'm trying to decrease the Time Dependent Valuation (TDV) total for a building. Thermal energy storage is perfect for this since the tank can be charged with a chiller during off peak hours at night and discharged during on peak hours for cooling instead of the chiller.

However, I ran the IceStorage-Series-ChillerDownstream.idf energyplus example file during the months of June, July, and August and measured the TDV with and without use of the Ice Tank, and the difference in TDV was small, and sometimes increased if I autosized certain values.

Looking deeper into the simulation results, looks like the Ice Tank isn't being fully utilized with the chiller still running most of the time.

image description

As you can see, the chiller is running when it's hot outside during on peak hours and the Ice Tank still has a lot of cooling capacity left.

I tried making the Ice Tank capacity 100 times larger, so WAY more than the building needs, but the chiller still turns on when the Ice Tank could easily handle all the cooling load.

So my question is: How do I get the chiller to run only when charging the Ice Tank at night, or during the day AFTER the Ice Tank has been completely used up?

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answered 2019-03-05 17:21:16 -0500

mldichter gravatar image

updated 2019-03-05 17:21:53 -0500

I was dismayed when I found that even the IceStorage-Parallel.idf did not work as I had hoped. Charging and discharging did not always occur at night and work hours respectively.

I won't be accepting this answer as I was never able to get the ice tank and chiller to behave exactly as I wanted using built in control objects in energyplus, and even using EnergyManagementSystem objects did not fully work, but mostly worked.

However, at least the person reading this will know to skip the built in objects and try EMS for controlling the ice tank.

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Asked: 2019-02-26 11:15:08 -0500

Seen: 120 times

Last updated: Mar 05