[esp-r] basic controller for dehumidification control

[Tobias Zitzmann]

Dear users,

has anybody experiences with the humidification control of the basic 
zone controller?

Our model setup: Our test room model is a single zone, contains a fixed 
infiltration flow rate and has no internal gains (using opr-file). A 
basic zone controller is used for cooling and dehumidification control 
(setpoints for dehumidification e.g.: maximum RH 30%, maximum 
humidification rate 1g/s). Summer weather conditions of south Germany 
are used.

The problem: As a result, the relative humidity target within the room 
is always achieved due to dehumidification, although the results 
analysis manager output shows dehumidification loads which are 
significantly smaller than what would be theoretically expected (from 
Mollier-h-x diagram) in order to achieve the RH target.
For testing, we have drastically reduced the maximum dehumidification 
rate to 0.1 g/s. Consequently, the RH target is sometimes not achieved 
and the maximum dehumidification load output is 0.25 kW (which seems 
correct as 1g/s should equal 2.5 kW). However, for this small 
dehumidification load, the RH should be much higher than what is 
calculated by ESP-r. In other words, the dehumidification load output 
does not seem to suit to the calculated RH and is significantly smaller 
than it would be expected from h-x diagram for achieving the resulting RH.

The error seems to increase with higher room air changes (see examples 
below):

_Example 1_

*Conditions:*
Air change rate of 11.56h-1
Ambient T and RH 18.35°C and 77.5%
Zone T and RH 17.76°C and 30%
*Resulting dehumidification load:*
Theoretical: 2370W
ESP-r output: 360 W
Difference: 86%

_Example 2_

*Conditions:*
Air change rate of 1.0h-1
Ambient T and RH 18.35°C and 77.5%
Zone T and RH 18.0°C and 30%
*Resulting dehumidification load:*
Theoretical: 203W
ESP-r output: 140W
Difference: 32%

Has anybody an idea about this phenomenon? We saw this problem in the 
newest version of ESP-r and also in an older version. Any comment is 
appreciated.

Regards,

Tobias

-- 
Dr. Tobias Zitzmann
Project Manager
Dept. Thermal Systems and Buildings
Fraunhofer-Institut für Solare Energiesysteme ISE
Heidenhofstraße 2, 79110 Freiburg, Germany
Phone: +49 (0) 7 61/ 45 88-55 82  Fax: +49 (0) 7 61/ 45 88-95 82
tobias.zitzmann(at)ise.fraunhofer.de
http://www.ise.fraunhofer.de

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