[Bldg-sim] DOAS and chilled beam/radiator

[Sami, Vikram]

If you are using an active chilled beam, then you don't need to model the doas - just use 100% OA for your ahu.

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 -----Original Message-----
From:   沈洁 [mailto:shenjie820730 at hotmail.com]
Sent:   Friday, August 12, 2011 04:25 AM Central Standard Time
To:     bldg-sim at lists.onebuilding.org
Subject:        [Bldg-sim] DOAS and chilled beam/radiator





Hi, all；



I’m simulating a project with chilled beam/radiator plus dedicated fresh air system, I search from archive, it seems most of you using DOAS (a dummy zone) and IU/FCU to simulate, DOAS provide the fresh air and IU/FCU use the “Outdoor air from” DOAS, the radiator use baseboard instead with zero fan energy power.



But the DOAS in my project is 1) variable speed to reduce the fresh air energy base on occupancy schedule; 2) wheel heat recovery with exhaust air; 3) during the transition period, the DOAS will bypass the wheel to provide maximum fresh air to offset all the heating and cooling demand and chilled beam and radiator will shut off.



Now, my method is :

1)  using VAV system to represent DOAS , enter the “ Design supply/return “ flow to show the DOAS fresh air and exhaust air volume;

2) Define the wheel heat recovery with fresh air and exhaust air, and operation control is “OA exhaust DT”

3) Define the dummy with the same maximum fresh air volume, and also control the cool and heat temperature (otherwise the heat recovery will not work at all).

It seems works very well. But when I reading hourly report, I found the fresh air volume keeps the maximum all the time, so the fan running at the rated power the whole year, which results in the large fan energy consumpation.

How can I make the DOAS’s fresh air volume variable and fan variable according to the acutal IU/FC’s fresh air volume ??

Any comments and suggestions will be appreciated.



Eleanor Shen (沈洁）
Consultant
Environmental Resources Management

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