Issue with VRF with DOAS Measure

Hi,

To model VRF DOAS system, I use VRF with DOAS Measure (developed by Xcel Energy). Although VRF system is successfully replaced, the program fails due to an error when I run the Measure on Open Studio 3.0.1.

" *FATAL:GetVRFInput: Errors found in getting AirConditioner:VariableRefrigerantFlow system input. Preceding condition(s) causes termination"

Moreover, in some building models, an error Immediately occurs when I apply the measure to the model.

I would appreciate it if you could help me to figure out how to solve these problems

109

yashar

asked 2021-01-11 12:59:10 -0500

14.1k

Aaron Boranian

updated 2021-01-12 09:24:30 -0500

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@yashar could you include the severe error line from the EnergyPlus error file created by OpenStudio? You should find it in the run folder within the folder that has the same name as your OSM (OpenStudio model file). That will give more information about why the VRF with DOAS Measure isn't working correctly.

Aaron Boranian (2021-01-12 09:27:44 -0500) edit

Hi Aaron,

Thank you very much for your response. Unfortunately, It seems it is not possible to attach a file, but in the error file number of severe error is zero. It is the part of the error file:

program Version,EnergyPlus, Version 9.3.0-baff08990c, YMD=2021.01.12 11:41, * Warning * Sizing:System="DOAS - BUILDING STORY 1", invalid combination of inputs. * ~~~ * Type of Load to Size On = VENTILATIONREQUIREMENT and System Outdoor Air Method = VENTILATIONRATEPROCEDURE.

* Fatal * GetVRFInput: Errors found in getting AirConditioner:VariableRefrigerantFlow system input. Prec

yashar (2021-01-12 12:29:44 -0500) edit

CONDITIONER VARIABLE REFRIGERANT FLOW 1 HEATINGEIRLOWPLR 1 has out of range value. * ~~~ * ...Curve minimum value of X = 0.500 must be <= Minimum Heat Pump Part-Load Ratio = 0.250. * Fatal * GetVRFInput: Errors found in getting AirConditioner:VariableRefrigerantFlow system input. Preceding condition(s) causes termination. ...Summary of Errors that led to program termination: ..... Reference severe error count=0 ..... Last severe error= *** Warning: Node connection errors not checked - most system input has not been read (see previous warning).

yashar (2021-01-12 12:30:12 -0500) edit

@yashar thanks. Could you actually provide a link to the full text of the error file via Dropbox, Google Drive, etc.? Or update your post to show the full text instead of just the fatal error line? That would be easier to see all the model's issues. I can see two here, but there may be more.

Aaron Boranian (2021-01-12 13:01:01 -0500) edit

@aaron, appreciate for your time and help. You can find the error file here link text.

yashar (2021-01-12 15:07:24 -0500) edit

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I will "translate" the important warning messages that appear to be causing the simulation to stop.

** Warning ** GetVRFInput: AirConditioner:VariableRefrigerantFlow="VRF HEAT PUMP - BUILDING STORY 1", invalid
**   ~~~   ** ...Cooling Energy Input Ratio Modifier Function of Low Part-Load Ratio Curve Name = AIR CONDITIONER VARIABLE REFRIGERANT FLOW 1 COOLINGEIRLOWPLR has out of range value.

A VRF system with a VRF heat pump named VRF HEAT PUMP - BUILDING STORY 1 has an invalid performance curve named AIR CONDITIONER VARIABLE REFRIGERANT FLOW 1 COOLINGEIRLOWPLR. This performance curve is applied to the Cooling Energy Input Ratio Modifier Function of Low Part-Load Ratio Curve Name input field for the VRF heat pump and its value is out of range.

**   ~~~   ** ...Curve minimum value of X = 0.500 must be <= Minimum Heat Pump Part-Load Ratio = 0.250.

The performance curve named AIR CONDITIONER VARIABLE REFRIGERANT FLOW 1 COOLINGEIRLOWPLR has a minimum value of the X independent variable (cooling part-load ratio, in this case) set to 0.5, yet the Minimum Heat Pump Part-Load Ratio input field for the VRF heat pump is set to 0.25.

This same issue is seen as similar groups of warning lines in your error file for the Heating Energy Input Ratio Modifier Function of Low Part-Load Ratio Curve Name input field assigned to the performance curve named AIR CONDITIONER VARIABLE REFRIGERANT FLOW 1 HEATINGEIRLOWPLR. These heating and cooling performance curve issues are repeated for another VRF heat pump in the model, VRF HEAT PUMP - BUILDING STORY 2.

If you can reduce the minimum X of the performance curves to 0.25, that should get rid of these VRF warnings and allow the simulation to finish (unless new warnings or severe errors occur after this fix).

14.1k

Aaron Boranian

answered 2021-01-13 15:52:59 -0500

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@aaron, Really appreciate for your help. I changed htgCapFuncFlowFracCurve.setMinimumValueofx(0.5) (Line 1334) and clgEirFuncFlowFracCurve.setMinimumValueofx(0.5) from 05 to 0.25, but I still have the same error. I am wondering if I changed the right lines or not. You can find VRF with DOAS Measure here. Thank you very much for taking your time to review it.

yashar (2021-01-16 21:19:47 -0500) edit

@aaron, Hi Aaron, hope you are doing well. Unfortunately, I could not solve the problem. In fact, I made several changes, but the same errors still exist. I would appreciate it, if you can help me to find the parts of the code that are responsible for errors.

yashar (2021-01-20 11:50:21 -0500) edit

@yashar after you update the code within a measure.rb file, you need to update your measure by clicking on the Sync Project Measures with Library button within the Measures tab of the OpeStudio Application. This is also automatically done if you close and re-open the OpenStudio Application. Have you done either of those steps?

Aaron Boranian (2021-01-21 09:16:30 -0500) edit

@aaron, Thank you very much for your response. I saved my changes and applied it to several models, but the same error still exist. I am wondering if I made the right changes on Measure or not. As I mentioned above, I changed set minimum value of x in lines 1334 and 1408 (these parts are related to ASHP).

htgCapFuncFlowFracCurve.setMinimumValueofx(0.5) (Line 1334) clgEirFuncFlowFracCurve.setMinimumValueofx(0.5) (1407)

Have you successfully applied this Measure to your models?

I am so sorry for taking your time.

yashar (2021-01-21 10:10:53 -0500) edit

@yashar no, I have not used that measure myself before. It looks like you have altered the lines in resources/OsLib_HVAC.rb to change the minimum values IF you are combining the central VRF with zone air-source heat pumps (ASHPs). Is that the case?

Has this measure worked when you applied it to other models, or are they all having this issue? If it works for other models, then something unique about this model isn't working with the measure.

The best resource to help you out is the measure's author, @David Goldwasser

Aaron Boranian (2021-01-22 15:00:16 -0500) edit

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@yashar, That measure was developed by Xcel Energy and was last updated in 2016. Try to use the newer NZE HVAC measure that NREL maintains. There is a system type argument choice available named "DOAS with VRF"