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TRNYS: simulation of chiller and cooling tower

asked 2021-03-11 05:15:45 -0500

radni gravatar image

updated 2021-04-17 13:45:02 -0500

Hi, I'm new on TRNSYS to simulate water cooled chiller and cooling tower.

I try to import load, only temperature and flow then connect data to water cooled chiller, type 666 via "chilled water inlet temperature" and "chilled water flow rate" then connect chiller to cooling tower. My issue is that water flow that goes to cooling tower is constant: 110 000 kg/hr (default vaule) and water temperature of the return flow from cooling tower changed. But I want to fixed temperature at ~30oC and variable water flow to cooling tower.

So the question: Is there any automatic calculation to achieve this (variable flow and fixed temperature) or it has to do manual calculation of the flow via Equa tool then put this result to chiller via "cooling water flow rate".


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@radni so are you trying to vary the flow rate and fix the temperature of condenser water flowing between chiller and cooling tower, while also importing the chilled water load for the chiller to meet via chilled water flowing between chiller and chilled water demand components (cooling coils, e.g.)?

Aaron Boranian gravatar image Aaron Boranian  ( 2021-03-11 08:49:09 -0500 )edit

yes, I'm doing simple test. Importing 8760h of flow and temperature from other software, connect them into chiller type 666, "chilled water inlet temperature" and "chilled water flow rate" then simply demand chiller supply temperature at 5oC, not connect to any cooling coil yet. I expected that water flow to cooling tower will be variable and return water temperature (from cooling tower) is around 30oC. But I got fixed cooling tower flow and variable temperature.

radni gravatar image radni  ( 2021-03-11 09:33:41 -0500 )edit

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answered 2021-03-18 09:33:33 -0500

Tim McDowell gravatar image

In TRNSYS 18, Cooling Tower component Type161 tries to control the leaving water temperature by modifying the flow on the air side. If you want to modulate the water flow you will need to apply a variable speed pump component and determine your own algorithm for modifying the flow rate to maintain the leaving temperature. I warn you that this is a very difficult control equation to figure out.

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thank you, it's what I think I have to do manually.

radni gravatar image radni  ( 2021-03-21 07:03:54 -0500 )edit

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