Unmet Hours

How to model ducts?

asked 2019-05-31 13:51:33 -0500

mldichter
2555 ●2 ●10

We are doing a research project to explicitly model duct leakage in a building. The model needs to take into account the geometry of the ducts. In the past for EnergyPlus 8.0, we explicitly modeled ducts as individual zones with many leakages specified for each surface of the duct, and we took into account different amounts of leakages further down the length of a duct. For instance, the multistory building had a vertical duct to feed all the zones in the building, so the top and bottom zones of the duct leaked different amounts. Creating the model was a laborious endeavor.

However, we are happy to note that the AirFlowNetwork has been upgraded significantly since EnergyPlus 8.0 and we are hoping there is a more straightforward way to model the differing amounts of leaks in the duct system. How would you go about making a detailed simulation of duct leaks in the most recent version of EnergyPlus?

answered 2019-06-03 12:26:31 -0500

Aaron Boranian

13830 ●76 ●24 http://bigladdersoftware.com/

If you are using Airflow Network objects, then to account for convective heat transfer on inner and outer surfaces of ducts use the AirflowNetwork:Distribution:Component:Duct object. To model supply or return air leakage in ducting, use the AirflowNetwork:Distribution:Component:Leak or AirflowNetwork:Distribution:Component:LeakageRatio objects.

There is a similar post on Unmet Hours here that you can refer to about modeling ducts and their leakages in EnergyPlus Airflow Network objects.

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@Aaron Boranian Is there a way to specify the zone where the duct has convective heat transfer and leakage to? I am trying to model duct losses in an attic in all seasons.

mldichter ( 2019-11-28 14:59:26 -0500 )edit

If you include an AirflowNetwork:Distribution:Linkage object with the Thermal Zone input field set to the zone surrounding the ducting, that sh\would account for conduction heat losses from the ducting to the zone, but it doesn't sound like it captures the convective and flow leakage losses from ducting to the zone. You may need to apply EMS to have sensors for leakage flow rate and set those last two heat loss components manually.