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OpenStudio / EnergyPlus Support for Refrigeration Heat Reclaim from Transcritical Gas Coolers

asked 2026-01-21 10:26:28 -0500

mdeslauriers's avatar

updated 2026-04-27 13:43:35 -0500

Hi everyone,

I’m modeling space heating heat reclaim savings in OpenStudio for a supermarket with transcritical refrigeration and running into a limitation I wanted to check with the group.

For non‑transcritical systems, I’ve successfully used OS:Coil:Heating:Desuperheater with OS:Refrigeration:Condenser:AirCooled as the heating source. That approach is working as expected.

For the transcritical systems, OS:Refrigeration:GasCooler:AirCooled is now my heating source, but this setting is not sticking as the heating source for the desuperheater coil. Based on the EnergyPlus I/O Reference, it looks like Refrigeration:GasCooler:AirCooled objects aren’t valid heating sources for desuperheater coils.

Has anyone found a workaround to successfully model transcritical refrigeration heat reclaim in EnergyPlus / OpenStudio? Alternatively, is anyone aware of planned development to support gas coolers as valid heat sources for desuperheater coils in future versions?

Docs for reference:

link:EnergyPlus I/O Reference for Coil:Heating:Desuperheater - Heating Source Object Type

Any ideas would be greatly appreciated. Thanks!

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Do you mean OS:Refrigeration:Condenser:AirCooled in the non-transcritical scenario?

I suspect the only way you're going to be able to accomplish this within E+ is to use EMS or Python EMS. But it may be tricky even then.

Craig Simmons's avatar Craig Simmons  ( 2026-02-02 10:44:56 -0500 )edit

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answered 2026-05-04 05:04:13 -0500

PmP's avatar

It's hard coded to give a severe error (and most likely, the error flag stops the simulation) if the source of heat isn't one of the valid ones from the list. See "https://github.com/NatLabRockies/Ener...".

Several functions for each case would need to be coded (Look for correct gas cooler, check it's temperature, etc.). I have made several transcritical refrigeration source code modifications to add new functionalities and this one seems not easily approachable.

As for a workaround, I can think of one. Simulate once without heat recovery, getting the total gas cooler heat removal as a result. Then do a second simulation with that ammount of heat being generated inside of a "fake" zone (make it very small, 0 occupation, no lighting, etc), via scheduled load generation, like equipment with 0 electrity consumption. Have that zone have heat removed via a cooling coil, and use that cooling coil as the heating source for the desuperheater coil.

Be careful with temperatures: the gas cooler generates heat at a particular temperature, but the equivalent heat load generated inside this fake zone does not account for it. Also careful with fans so you are not counting twice for ventilation purposes.

Hopes this it is of some use to you!

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Asked: 2026-01-21 10:26:28 -0500

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Last updated: May 04