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Did someone use a refrigeration system with R744 in OpenStudio?

asked 2023-01-05 10:31:15 -0600

Elias Eid's avatar

updated 2023-01-06 09:44:22 -0600

Hello, I am modelling Supermarkets in EnergyPlus by using OpenStudio. This includes the building, hot water system, interactions between HVAC and refrigeration systems, etc. I have many questions concerning refrigeration system in OpenStudio. I am using R744 in OpenStudio. However, I get a warning message in the ERR file stating that the temperature is going out of the range. I tried to change from a subcritical operation to a transcritical operation (when I click on the compressors), but I still get the same warning message concerning R744. The problem is that I don’t have access to the thermal physical properties of R744 in EnergyPlus to check the range and fix the problem. However, when I switch to another refrigerant, the error message disappears. Any idea? Many thanks in advance.

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answered 2023-01-07 14:59:00 -0600

Petros Dalavouras's avatar

Assuming that you use air to reject heat and that you do not have a cascade system (CO2-R134a), CO2 has a low critical point therefore requires a gascooler instead of a typical condenser. Moreover, you require a TranscriticalSystem object to model these systems. There is not a gas cooler object in openstudio application nor a transcritical system so you need to either insert them via a measure or manually by modifying the txt.

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Yes, apparently we need to create a new measure to include them in OpenStudio since the TranscriticalSystem and the GasCooler are not available in Openstudio. Many thanks for your reply Petros.

Elias Eid's avatar Elias Eid  ( 2023-01-11 06:24:25 -0600 )edit

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Asked: 2023-01-05 10:31:15 -0600

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Last updated: Jan 07 '23