I do not know the answer.
However, in real world, it is not done in the way you have described.
For human generated CO2, it is taken care of by the minimum fresh air intake volume per person. For the furnace generated CO2, it is piped to the OA with a chimney.
In a special controlled air space, CO2 is removed by chemical absorption, in the air filtering plant.
House plant is another way of reducing CO2 level in office buildings, however, plant also gives out CO2 when there is no light. It is also a humidifier.
Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: jeannieboef@xxxxxxxxx
Date: Sat, 24 Sep 2011 11:23:41 +0000
Subject: [EnergyPlus_Support] Real world HVAC question - DCV using CO2 sensors with VAV dampers
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However, in real world, it is not done in the way you have described.
For human generated CO2, it is taken care of by the minimum fresh air intake volume per person. For the furnace generated CO2, it is piped to the OA with a chimney.
In a special controlled air space, CO2 is removed by chemical absorption, in the air filtering plant.
House plant is another way of reducing CO2 level in office buildings, however, plant also gives out CO2 when there is no light. It is also a humidifier.
Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: jeannieboef@xxxxxxxxx
Date: Sat, 24 Sep 2011 11:23:41 +0000
Subject: [EnergyPlus_Support] Real world HVAC question - DCV using CO2 sensors with VAV dampers
This question has nothing to do with simulation as such. What is the best way to use / control a Demand Control Ventilation (DCV) System which uses a combination of CO2 sensors and motorized Variable Airflow Volume (VAV) dampers.
I will suggest a control stradegy to illustrate the question:
CO2 sensors report the zone CO2 level at given timestep.
Allowable upperbound CO2 level is 800ppm.
Outdoor Air (ODA) CO2 level is 400ppm.
Minimum damper position allows at least 0.3 of fully open flow.
Maximum damper position is fully open, i.e. 1.0 of full flow.
Stradegy 1::
Control is such that at 400 ppm, Damper will be at 0.3 of full flow.
At 800 ppm or more, Damper will be fully open.
Damper is linierly actuated between 0.3 to 1 as the level of zone CO2 increases from 400 ppm to 800 ppm.
Stradegy 2::
Damper remains at 0.3 untill CO2 level reaches 750 ppm, then linierly opens from 0.3 to 1.0 as the level increases to 800 ppm.
Stradegy 3::
Erratic opening and closing of damper only when level reaches or goes over 800 ppm.
Stradegy 4::
Exponencial, or other curve to control damper other than liniear.
Origional question...how are these systems controlled in practice?
Anyone with experience, here?
I will suggest a control stradegy to illustrate the question:
CO2 sensors report the zone CO2 level at given timestep.
Allowable upperbound CO2 level is 800ppm.
Outdoor Air (ODA) CO2 level is 400ppm.
Minimum damper position allows at least 0.3 of fully open flow.
Maximum damper position is fully open, i.e. 1.0 of full flow.
Stradegy 1::
Control is such that at 400 ppm, Damper will be at 0.3 of full flow.
At 800 ppm or more, Damper will be fully open.
Damper is linierly actuated between 0.3 to 1 as the level of zone CO2 increases from 400 ppm to 800 ppm.
Stradegy 2::
Damper remains at 0.3 untill CO2 level reaches 750 ppm, then linierly opens from 0.3 to 1.0 as the level increases to 800 ppm.
Stradegy 3::
Erratic opening and closing of damper only when level reaches or goes over 800 ppm.
Stradegy 4::
Exponencial, or other curve to control damper other than liniear.
Origional question...how are these systems controlled in practice?
Anyone with experience, here?
__._,_.___
Primary EnergyPlus support is found at:
http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx
The primary EnergyPlus web site is found at:
http://www.energyplus.gov
The group web site is:
http://groups.yahoo.com/group/EnergyPlus_Support/
Attachments are currently allowed but be mindful that not everyone has a high speed connection. Limit attachments to small files.
EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
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