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[eQuest] How does the supply flowrate autosized?

asked 2021-05-13 02:27:40 -0500

Oscar Yip's avatar

updated 2021-05-17 14:39:37 -0500

Hi All,

We can assign the design supply flow and min flow at system and zone level. What if we left them blank? How does the programme auto-size the supply flow rate? Does it relate to the "DESIGN-COOL-T"?

Thanks a lot.

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answered 2021-05-13 10:39:22 -0500

Hi Oscar, I'm not familiar with equest, so this may not be very helpful, but for E+ the supply flow autosizing works like this:

The routine starts at the Sizing:Zone object, where you can specify zone_cooling_design_supply_air_temperature. With this parameter E+ is then calculating the air flow rate needed (at the given cooling design SAT and humidity ratio) to satisfy the specified zone loads (to meet your design thermostat setpoint). So your general control points are the temperature and humidity (to calculate enthalpy) of air being supplied to the zones (maybe this is DESIGN-COOL-T?), the thermostat design setpoint and the loads of each zone. SummerDesignDay temperature and humidity also play a factor (from the SizingPeriod:DesignDay object), as well as location, since those influence your zone loads as well. Zone level flow is calculated on a per zone basis, and then those are all summed up by air system to get the system level flow rate.

Hopefully that translates in a meaningful way to equest. Maybe there is a section in the equest documentation that digs into this routine as well.

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Thanks! We do have a MIN-SUPPLY-T at the system level in eQuest, I guess it work very similar to the role of zone_cooling_design_supply_air_temperature you described.

Oscar Yip's avatar Oscar Yip  ( 2021-05-13 21:23:21 -0500 )edit

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Asked: 2021-05-13 02:27:40 -0500

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Last updated: May 13 '21