[esp-r] Re: plant: air cooling coil

[Nicolas Kelly]

Dear Monica, 

 

For the P,PI or PID controller in set the 'mode' to a negative value (usually -1). The cooling flux should be specified as a positive value as it is negated in the cooling controller. To set an acceptable temperature range for the cooling coil adjust the 'throttling range' control parameters. The coil will operate proportionally between setpoint +/- 0.5*throttling range. So to control between 20 and 40 the set point is 30 and the throttling range is 20. 

 

Note that with HVAC modelling you will have some excursions from the desired values - you are modelling non-ideal processes and non-ideal controllers. Further, proportional control always has an 'offset' error, the size of which usually depends upon the size of the throttling range and the capacity of the component being controlled.

 

Regards, 

 

Nick Kelly on behalf of ESRU

 

 

*******************************

Dr Nick Kelly

RCUK Academic Fellow

Energy Systems Research Unit

Institute for Energy and Environment

University of Strathclyde

75 Montrose St

Glasgow G1 1XJ

t: +44(0)141 548 2854

f: +44(0)141 552 5105

e: nick at esru.strath.ac.uk <mailto:nick at esru.strath.ac.uk> 

*******************************

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From: esp-r-bounces at lists.strath.ac.uk [mailto:esp-r-bounces at lists.strath.ac.uk] On Behalf Of Monika Hall
Sent: 12 October 2006 12:13
To: Ferguson, Alex; esp-r at lists.strath.ac.uk
Subject: [esp-r] Re: plant: air cooling coil

 

Hi Alex and all other,

 

the first view was ok with a negative flux, I changed it in the ctl file. But when I changed it per menu, I got the error message, that the value have to be > 0. 

 

Additionally there must be something wrong, because I can not reach the setpoint temperature. I would like to cool a room with a cooling coil, if the room air temperature is higher then 26°C. The only way to handle the air temperature is due to variation of the cooling flux, but this is dissatisfying.

 

On the other side, the case with heating works fine. The heating coil heats, when the room air temperature is below the setpoint of 20°C.

 

Does anybody know if there is a possibility to set a temperature range for the heating/cooling coil? P.e. the temperature of the heating coil should be between 20 - 40°C and for the cooling coil between 16 - 24°C.

 

Best regards

Monika

 

________________________________

From: Ferguson, Alex [mailto:AFerguso at NRCan.gc.ca] 
Sent: Wednesday, October 11, 2006 4:38 PM
To: Monika Hall; esp-r at lists.strath.ac.uk
Subject: RE: [esp-r] plant: air cooling coil

Hi Monika,

 

The cooling coil model (CMP04) expects the control signal to be negative (i.e. -2000 for a 2000 W cooling duty.)

 

- Alex 

 

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From: esp-r-bounces at lists.strath.ac.uk [mailto:esp-r-bounces at lists.strath.ac.uk] On Behalf Of Monika Hall
Sent: Wednesday, October 11, 2006 10:32
To: esp-r at lists.strath.ac.uk
Subject: [esp-r] plant: air cooling coil

Dear all,

 

have anybody worked with the plant component " air cooling coil, ref. no 4"? My model works fine with the plant component  " air heating coil, ref. no 5", but when I change the heating coil into a cooling coil the model does not work anymore. 

 

I use the same controller for heating/cooling coil:

controller type a) senses dry bulb  -> actuates flux

Control law b) P,PI,PID for type 0,2,4...

 

I use the same settings for heating/cooling, I only change the setpoints.

 

The error code is:

CMP04C: invalid control data for component 2: 2000

with 2: Cooling coil and 2000: max htg/clg cap [W]

 

Which setting is the right one for a cooling coil? Could somebody help me?

 

Best regards

Monika

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