System Node Mass Flow 0 when connecting PVT air to ERV

I want to simulate a facade-integrated PVT solar collector which preheats the outdoor supply air for the ERV energy recovery ventilation system (heat exchanger:airToAir:sensibleAndLatent). There is no other heating/cooling/plant/HVAC system in my single room model, located here for reference: https://www.dropbox.com/s/xjbpu33iqu4....

The file runs with the warning, that my 'SolarCollectorPerformance:PhotovoltaicThermal:Simple' object is unused, and the simulation results give 0 kg/s system node mass flow rate for the PVTinlet. I assume, that my PVT is not properly referenced in the outdoor air ERV system, however, I'm not sure how to solve it. I've used the 'shopwithsimplePVT.idf' sample file for reference. That file, however, comes with an AirLoopHVAC system, which my ERV does not have. In that reference, the PVT collector is referenced in 'airLoopHVAC:OutdoorAirSystem:EquipmentList'. Since my ERV system (which I made based on another EnergyPlus sample idf) does not require this, I tried to reference the PVT collector in 'ZoneHVAC:EquipmentList'. However, the PVT solar collector does not appear there as an object type. Hence, for now, the PVTinlet (which is the outdoor air inlet of the PVT collector), is only mentioned in the PVT object and in the NodeList.

How should I further link my PVT collector to my ERV system, or is there another problem I am overseeing? Do I need to add the entire AirLoopHVAC system with branch and outdoorAirMixer as in the sample file to my simple ERV system? Any help on this is greatly appreciated!

MVR

asked 2022-03-23 13:49:16 -0500

14.1k

Aaron Boranian

updated 2023-04-22 08:03:14 -0500

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Where is the HX referenced? Oh, I see, the ERV.

rraustad (2022-03-23 15:22:25 -0500) edit

Added a suggestion for improvement to EnergyPlus at https://github.com/NREL/EnergyPlus/is...

rraustad (2022-03-23 16:05:44 -0500) edit

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The name and likely the type of PVT needs to be entered somewhere for the model to be called. Since you are using outdoor air the likely place would be an outdoor air system as you see in the example file. Another place would be the ZoneHVAC:EnergyRecoveryVentilator except that this model is not allowed as an input (which would be a nice improvement to EnergyPlus). So your only option as I see it is to install an air loop and configure it as 100% outdoor air which would model exactly what you are doing now with just a little more work. In the outdoor air system equipment list, enter the type and names of the HX and PVT. And of course, remove the ZoneHVAC:EnergyRecoveryVentilator you are using now.

In the Energy+.idd file, this object is allowed to be referenced in the OA system or a branch or plant object, none of which you are currently using. The simplest thing to do is add a 100% OA system.

SolarCollector:FlatPlate:PhotovoltaicThermal,
 \memo Models hybrid photovoltaic-thermal (PVT) solar collectors that convert incident solar
 \memo energy into both electricity and useful thermal energy by heating air or water.
  A1 , \field Name
       \reference-class-name validOASysEquipmentTypes
       \reference validOASysEquipmentNames
       \reference-class-name validBranchEquipmentTypes
       \reference validBranchEquipmentNames
       \reference-class-name validPlantEquipmentTypes
       \reference validPlantEquipmentNames