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Modelling a ground-source heat pump with underfloor heating and cooling [EnergyPlus]

Hi!

I am trying to model a heating and cooling systems that uses a ground-source loop and then a water-to-water heatpump to be used in an underfloor heating and cooling system (the same tubes are used, just in a different mode). This has probably been done, but I can't seem to find the appropriate water-to-water heatpump.

I am looking at combining ZoneHVAC:LowTempRadiant:VariableFlow with a WaterHeater:HeatPump:EIR:(Heating/Cooling), but I don't see how I would use the same system for both heating and cooling? I am pretty new to modelling my own systems with custom nodes, pipes and so on, so forgive me the basic question.

Thanks in advance for your answers!

Update 11-12-23: Solution found (see Keigo's answer below and the final version in EP v9.2 language on Dropbox here: https://www.dropbox.com/scl/fi/fe4n3o...)

Gijs_WE's avatar
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Gijs_WE
asked 2023-12-04 10:31:12 -0500, updated 2023-12-11 02:26:13 -0500
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@Gijs_WE what simulation tool are you using? Please mention it in the title or body of your post, as well as add a tag so that others can provide better help. It sounds like you're using EnergyPlus based on the object types that you've mentioned.

Also, if you can upload your model to Google Drive, Dropbox, etc. and then share a URL for others to download, that would help others provide better solutions.

Aaron Boranian's avatar Aaron Boranian (2023-12-04 11:45:17 -0500) edit
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You should use HeatPump:WaterToWater:EquationFit:Cooling and HeatPump:WaterToWater:EquationFit:Heating or HeatPump:WaterToWater:ParameterEstimation:Cooling and HeatPump:WaterToWater:ParameterEstimation:Heating.

Please refer to ExampleFiles GSHP-GLHE.idf, GSHP-GLHE-CalcGFunctions-cpg.idf, GSHP-GLHE-CalcGFunctions.idf, GSHP-Slinky.idf and GSHPSimple-GLHE.idf.

EnergyPlus cannot switch between chilled water and hot water in one plant loop. You need to model two separate plant loops: one is for chilled water and the other is for hot water. Even if there is actually one heat pump, two heat pumps need to be modelled in EnergyPlus: one is for cooling only and the other is for heating only.

Keigo's avatar
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Keigo
answered 2023-12-11 01:00:53 -0500
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Thank you for the answer! I managed to make this work with indeed two separate heat pumps and also two ground heat exchangers as model for the ground source. I found the EquationFit the easiest way to model the system as it allows easy implementation of both COP and heating/cooling capacity (which I know from the supplier). For other people that want to use this system: take care that if you also want the ground loop to function, you also need a separate Condenser Loop to use a Ground Heat Exchanger!

Gijs_WE's avatar Gijs_WE (2023-12-11 02:21:14 -0500) edit
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