Civil Engineering Reference
In-Depth Information
under both situations, with the indoor air velocity set up as a constant value and using a
filtered value of it. Hence, to demonstrate the performance of these techniques around
the whole year, several tests have been performed along the summer period using a
filtered value of the indoor air velocity.
5.4.3.3 Tests (C) and (D): Performance Analysis of the Proposed Control
Approach Along the Summer Period
In order to obtain real results from the summer period, the hierarchical NMPC
approach has been tested during June and July, 2013. The main features of the tests
are the same as the ones previously presented for the winter period, that is, the test
duration is approximately five hours, from 9 a.m to 14 p.m.. These tests have been
carried out during different working days inside the selected room. The tests were
performed with a configuration almost identical to test (A) and (B), that is, with a
sample time of 240 s in the upper layer, that is, the PNMPC optimiser. As mentioned
previously, the sample time of the lower layer, the fancoil MISO controller, is 8 s.
Regarding other controller parameters, the prediction and control horizons are equal
to
N
00025, respectively, and finally, it is
subjected to the constraints defined by Eqs.
5.26
and
5.27
with
=
15 and
N
u
=
5,
˃
=
1 and
ˉ
=
0
.
5
◦
C,
u
min
=−
27
◦
C. As in the case of the summer
period, these lower and upper limits have been set up after several experimental tests
with the fancoil system to establish its physical limits.
The obtained results are organised in a similar way to the ones of test (A) and
(B), Figs.
5.31
and
5.34
show the relevant variables to evaluate the control strategy
proposed in this section. In Figs.
5.32
and
5.34
, it can be observed the dynamic
evolution of some of the most important variables that have influence on thermal
comfort, and finally, Figs.
5.33
and
5.34
, show a comparison between the energy
consumption derived from the HVAC system when both strategies are used: the
classical MPC approach and with the hierarchical controller presented in this section.
Furthermore, the results associated to this test (C) can be observed from
Figs.
5.31
-
5.33
. More specifically, as shown in the top graph of Fig.
5.31
, the devel-
oped control approach is able to maintain the PMV index equal to zero during the
summer period also. In addition, it can be observed in the third graph of Fig.
5.31
that
the energy efficiency defined by means of the split-range controller is also satisfied,
since it is shown that in a first attempt it tries to reach the impulse air temperature
setpoint using the fan velocity, and only when this variable is saturated, it begins to
use the water flow valve.
Moreover, the results obtained from test (D) which are shown in Figs.
5.34
,
5.35
and
5.36
are similar. As in the previous tests, it is able to both, reach and maintain a
PMV index value equal to zero. Furthermore, also in this test the constraints estab-
lished through the split-range controller are satisfied, as can be observed in the third
graph of Fig.
5.34
.
5
◦
C,
u
min
5
◦
C and
u
max
u
max
=
=
17
.
=
