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How do I troubleshoot a water-cooled condenser with no flow?

asked 2015-08-06 17:45:40 -0600

learntech gravatar image

updated 2015-08-11 12:46:19 -0600

I am attempting to model a refrigeration cycle with a water cooled condenser but am having troubles. The system runs however the results show that there is no mass flow of water through the loop.

It is a simple box building with 1 walk-in refrigeration case and 1 compressor. The model works with air-cooled condenser, but the water cooled condenser however does not show any water flow or pump power.

I have also tries to plot pump power of the water loop and this also shows zero. I cannot seem to trouble shoot this system, any help or advice would be greatly appreciated.

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Do you have the water cooled condenser attached to the demand side of a plant loop with a pump, a cooling tower, and a setpoint manager on the supply side?

aparker gravatar image aparker  ( 2015-08-07 16:29:47 -0600 )edit

aparker, thank you for the response.

Yes, I have a water cooled condenser on the Demand side and a pump, variable speed cooling tower and set point manager on the supply side. I have also taken a screen shot of the loop. Is there any way for me to post it for reference? Sorry, I am brand new to Unmet hours community. Thanks again.

learntech gravatar image learntech  ( 2015-08-07 16:55:15 -0600 )edit

I am using OpenStudio Version 1.8.0

learntech gravatar image learntech  ( 2015-08-07 18:50:48 -0600 )edit

@learntech: edit your post, and you'll see an icon that looks like an image (in the taskbar where you have "B", "I", etc): click on it, upload your picture.

Julien Marrec gravatar image Julien Marrec  ( 2015-08-08 08:03:54 -0600 )edit

@learntech I edited your question to make it more readable, but it looks like some of the images you uploaded are duplicates.

MatthewSteen gravatar image MatthewSteen  ( 2015-08-11 12:42:42 -0600 )edit

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answered 2015-08-10 14:31:55 -0600

Archmage gravatar image

To troubleshoot, check that the system node at the inlet of the condenser is setting a non-zero value for the mass flow request. Add the following detailed time series output report.

Output:Variable,   < name of inlet system node>  ,System Node Requested Mass Flow Rate,detailed;

It should be non-zero. If it is zero, check the sizing results if you are autosizing and try hard sizing the condenser loop.

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Thank you for the response and feedback. Before I was auto sizing and getting 0 for mass flow through the inlet to the condenser. I have attempted hard sizing the condenser loop and I am still seeing 0 for the mass flow rate through the condenser loop, despite hard sizing the flow in the loop. I have attached screenshots to the original question. Any suggestions? Thank you very much for your help.

learntech gravatar image learntech  ( 2015-08-10 15:21:56 -0600 )edit

I would also check out the outputs for the Refrigeration:Condenser:WaterCooled to see if you are getting heat transfer through the condenser. Basically make sure the rest of your refrigeration rack is actually running.

aparker gravatar image aparker  ( 2015-08-10 15:38:11 -0600 )edit

Hey, thank you for the reply. I have uploaded images of more plots for this. My condenser does have heat transfer, but no flow rate... how could this be?

learntech gravatar image learntech  ( 2015-08-10 15:46:56 -0600 )edit

Nice pictures, but you are reporting "System Node Mass Flow Rate", not "System Node Requested Mass Flow Rate." Maybe you have turn on advanced reporting by adding this to get that output variable for trouble shooting: "Output:Diagnostics,DisplayAdvancedReportVariables;" Or set the operating system environment variable.

Archmage gravatar image Archmage  ( 2015-08-11 10:02:00 -0600 )edit

Hello Archmage, thank you for the advice. I don't think I am getting the correct outputs. I have attached another picture above. Am I placing the "DisplayAdvancedReportVariables" in the BCL outputs? Also, I can now get the pump to show up in energy usage however it is only through hard sizing the rated flow rate and rated power consumption in the plant loop. This does not seem to be the correct way to approach the problem.

learntech gravatar image learntech  ( 2015-08-11 11:56:59 -0600 )edit

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Asked: 2015-08-06 17:45:40 -0600

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Last updated: Aug 11 '15