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Indirect Air side Economizer

asked Mar 4

updated Mar 5

I am simulating an HVAC system for a data center.

I want to evaluate an indirect air-side economizer to take advantage of cold temperatures and prevent unwanted pollution and humidity from the outside (unlike a direct air-side economizer).

Since my return air in the AHU is 100% recirculated, OpenStudio doesn’t allow me to add an air-to-air plate heat HX exchanger.

It only allows it when I have an outdoor air (OA) system in my air loop.

Any ideas on how to do this? image description

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answered Mar 5

Greg Estep's avatar

updated Mar 5

Hello obuchely, What if you used a direct air side economizer with the following settings: Allow OA, use the air-to-air HX and set the heating sensible and latent effectiveness to 0% and the cooling sensible and latent effectiveness to 100%? This way the zone humidity is maintained and the heat exhausted. You will then need an economizer to bring in the cool OA. I think a fixed dry bulb type would work with the specified dry-bulb temperature limit set to zone thermostat setpoint. The economizer will modulate to meet the mixed air temperature setpoint. This should be the same as your cooling supply air setpoint. The economizer should be configured such that the heat recovery device is never bypassed (Economizer control action type: Modulate flow). I think that covers it.

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Asked: Mar 4

Seen: 50 times

Last updated: Mar 04