For Different Initial Conditions

3.1 On Water-to-Air Surface Heat Exchanger

3.1.2 For Different Initial Conditions

The influence of initial conditions on the transient thermal response characteristic of the heat exchanger is investigated as well by using the state-space model.

(1) Influence of initial inlet air temperature (ta, E)o

Three initial values of inlet air temperature (i.e., 30.0, 32.0, and 34.0 °C) combined with the other initial conditions ((tw, E)o= 15.0 °C, (Wa, E)o= 20.0 g/(kg dry air), (Ga)o= 0.20 kg/s,(Gw)o= 0.20 kg/s) are given for the dynamic thermal response simulation of water-to-air heat exchanger, and the corresponding system matrixes for the heat exchanger (Acoil,Bcoil) under these initial conditions are cal- culated as below:

Acoil;ta;Eẳ30CẳAcoil;ta;Eẳ32C

ẳAcoil;ta;Eẳ34Cẳ

0:5327 0 0 0:3072 0 4:4031 0:4860 1:9125 0 0:0011 2:9432 0:0066 0:0491 0:0380 0:2004 0:2803 2

66 64

3 77 75;

Bcoil;ta;Eẳ30Cẳ

0:0720 8:4627 0 0 0

0 0 1:8499 0:4860 29:3115 0 0 0:0011 2:9266 0:1325 0:0491 7:3084 0:0380 0:2004 0:0863 2

66 64

3 77 75;

Bcoil;ta;Eẳ32Cẳ

0:0720 8:7574 0 0 0

0 0 1:8499 0:4860 37:6962 0 0 0:0011 2:9266 0:1309 0:0491 8:1784 0:0380 0:2004 0:0236 2

66 64

3 77 75;

Bcoil;ta;Eẳ34Cẳ

0:0720 8:8831 0 0 0

0 0 1:8499 0:4860 42:9023 0 0 0:0011 2:9266 0:1293 0:0491 9:225 0:0380 0:2004 0:1267 2

66 64

3 77 75:

Figure3.5shows the dynamic responses of exit air temperature and humidity of the water-to-air heat exchanger under different initial inlet air temperatures. As shown in Fig.3.5, the dynamic response characteristics of exit air temperature and humidity to inlet air temperature and humidity as well as inlet water temperature will not affected by initial values of inlet air temperature. However, when subjected to the perturbations of water and airflow rate, the dynamic response characteristics of exit air temperature and humidity will be impacted by initial values of inlet air temperature. The results in Fig.3.5manifest that the ampliﬁcation coefﬁcient of response of exit air temperature and humidity to the perturbations of water and

0 0.1 0.2 0.3 0.4 0.5

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Time (s)

Change of response parameters

(ta,E)o=30.0 Response of exit air temperature ( ) (ta,E)o=32.0 Response of exit air temperature ( ) (ta,E)o=34.0 Response of exit air temperature ( ) (ta,E)o=30.0 Response of exit air humidity (g/(kg dryair) (ta,E)o=32.0 Response of exit air humidity (g/(kg dryair) (ta,E)o=34.0 Response of exit air humidity (g/(kg dryair)

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Time (s)

Change of response parameters

(a) Inlet air temperature has a step increase by 1.0

(b) Inlet air humidity has a step increase by 1.0 g/(kg dryair)

Fig. 3.5 Dynamic responses of exit air temperature and humidity to perturbations under different initial values of inlet air temperatureaInlet air temperature has a step increase by 1.0 °C.bInlet air humidity has a step increase by 1.0 g/(kg dry air).cAirflow rate has a step increase by 0.1 kg/s.

dInlet water temperature has a step increase by 1.0 °C.eWaterflow rate has a step increase by 0.1 kg/s

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Time(s)

Change of response parameters

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Time (s)

Change of response parameters

(d) Inlet water temperature has a step increase by 1.0

-2.4 -2.2 -2 -1.8 -1.6 -1.4 -1.2 -1 -0.8 -0.6 -0.4 -0.2 0

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Time(s)

Change of response parameters

(e) Water flow rate has a step increase by 0.1 kg/s Fig. 3.5 (continued)

airflow rate will be larger under the higher initial value of inlet air temperature, and this indicates that the impact of water and airflow rate of heat exchanger on its exit air temperature and humidity will be more signiﬁcant under the higher inlet air temperature.

(2) Influence of initial inlet air humidity (Wa, E)o

Three initial values of inlet air humidity (i.e., 18.0, 20.0, and 22.0 g/(kg dry air)) combined with the other initial conditions (i.e., (ta, E)o= 30.0 °C, (tw, E)o= 15.0 °C, (Ga)o= 0.20 kg/s,(Gw)o= 0.2 kg/s) are given for the thermal dynamic response simulation of water-to-air heat exchanger, and the corresponding system matrixes for the heat exchanger (Acoil,Bcoil) under these initial conditions are computed as below:

Acoil;Wa;Eẳ18:0ðkg=kgịẳAcoil;Wa;Eẳ20:0ðkg=kgịẳAcoil;Wa;Eẳ22:0ðkg=kgị

ẳ

0:5327 0 0 0:3072 0 4:4031 0:4860 1:9125 0 0:0011 2:9432 0:0066 0:0491 0:0380 0:2004 0:2803 2

66 64

3 77 75;

Bcoil;Wa;Eẳ18:0ðkg=kgịẳ

0:0720 8:3370 0 0 0

0 0 1:8499 0:4860 32:9884 0 0 0:0011 2:9266 0:1241 0:0491 6:2643 0:0380 0:2004 0:0393 2

66 64

3 77 75;

Bcoil;Wa;Eẳ20:0ðkg=kgịẳ

0:0720 8:4627 0 0 0

0 0 1:8499 0:4860 29:3115 0 0 0:0011 2:9266 0:1325 0:0491 7:3084 0:0380 0:2004 0:0863 2

66 64

3 77 75;

Bcoil;Wa;Eẳ22:0ðkg=kgịẳ

0:0720 9:4096 0 0 0

0 0 1:8499 0:4860 17:9014 0 0 0:0011 2:9266 0:1550 0:0491 8:8745 0:0380 0:2004 0:1673 2

66 64

3 77 75

Figure3.6shows the dynamic responses of exit air temperature and humidity of the water-to-air heat exchanger under different initial values of inlet air humidity. It is shown in Fig.3.6that the influence of initial inlet air humidity on the dynamic response characteristics of exit air temperature and humidity of water-to-air heat exchanger depends on the kind of disturbance parameters. The dynamic response characteristics of exit air temperature and humidity to the perturbations of inlet air temperature and humidity as well as inlet water temperature will not be affected by initial value of inlet air humidity. However, the initial value of inlet air humidity will make influence on the dynamic response characteristics of exit air temperature

and humidity when subjected to the perturbations of water and airflow rate.

As shown in Fig.3.6c, e, the ampliﬁcation coefﬁcient of response of exit air temperature and humidity to the perturbations of water and airflow rate will increase with the initial inlet air humidity increasing.

0 0.1 0.2 0.3 0.4 0.5

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Time (s)

Change of response parameters

(Wa,E)o=20 g/kg: Response of exit air temperature ( ) (Wa,E)o=22 g/kgResponse of exit air temperature () (Wa,E)o=24 g/kgResponse of exit air temperature () (Wa,E)o=20 g/kgResponse of exit air humidity (g/(kg dryair) (Wa,E)o=22 g/kgResponse of exit air humidity (g/(kg dryair) (Wa,E)o=24 g/kgResponse of exit air humidity (g/(kg dryair)

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Time (s)

Change of response parameters (Wa,E)o=20 g/kg: Response of exit air temperature ( ) (Wa,E)o=22 g/kg Response of exit air temperature ( ) (Wa,E)o=24 g/kg Response of exit air temperature ( ) (Wa,E)o=20 g/kg Response of exit air humidity (g/(kg dryair) (Wa,E)o=22 g/kg Response of exit air humidity (g/(kg dryair) (Wa,E)o=24 g/kg Response of exit air humidity (g/(kg dryair)

(a) Inlet air temperature has a step increase by 1.0 (b) Inlet air humidity has a step increase by 1.0 g/(kg dryair)

0 0.5 1 1.5 2 2.5

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Time (s)

Change of response parameters

(Wa,E)o=20 g/kg Response of exit air temperature ( ) (Wa,E)o=22 g/kgResponse of exit air temperature ( ) (Wa,E)o=24 g/kgResponse of exit air temperature ( ) (Wa,E)o=20 g/kgResponse of exit air humidity (g/(kg dryair) (Wa,E)o=22 g/kgResponse of exit air humidity (g/(kg dryair) (Wa,E)o=24 g/kgResponse of exit air humidity (g/(kg dryair)

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Time (s)

Change of response parameters

(Wa,E)o=20 g/kg: Response of exit air temperature ( ) (Wa,E)o=22 g/kgResponse of exit air temperature ( ) (Wa,E)o=24 g/kgResponse of exit air temperature ( ) (Wa,E)o=20 g/kgResponse of exit air humidity (g/(kg dryair) (Wa,E)o=22 g/kgResponse of exit air humidity (g/(kg dryair) (Wa,E)o=24 g/kgResponse of exit air humidity (g/(kg dryair)

-2.4 -1.9 -1.4 -0.9 -0.4

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Time (s)

Change of response parameters

(Wa,E)o=20 g/kg Response of exit air temperature ( ) (Wa,E)o=22 g/kg Response of exit air temperature ( ) (Wa,E)o=24 g/kg Response of exit air temperature ( ) (Wa,E)o=20 g/kg Response of exit air humidity (g/(kg dryair) (Wa,E)o=22 g/kg Response of exit air humidity (g/(kg dryair) (Wa,E)o=24 g/kg Response of exit air humidity (g/(kg dryair)

(e) Water flow rate has a step increase by 0.1 kg/s

Fig. 3.6 Dynamic responses of exit air temperature and humidity to perturbations under different initial values of inlet air humidity.aInlet air temperature has a step increase by 1.0 °C.bInlet air humidity has a step increase by 1.0 g/(kg dry air).cAirflow rate has a step increase by 0.1 kg/s.

dInlet water temperature has a step increase by 1.0°C (c) Airflow rate has a step increase by 0.1 kg/s .eWaterflow rate has a step increase by 0.1 kg/s

(3) Influence of initial airflow rate (Ga)o

Three initial values of airflow rate (i.e., 0.20, 0.22 and 0.24 kg/s) combined with the other initial conditions (i.e., (ta, E)o= 30.0 °C, (tw, E)o= 15.0 °C, (Wa, E)o= 18.0 g/(kg dry air), (Gw)o= 0.20 kg/s) are used to investigate the influence of initial airflow rate on dynamic thermal response of water-to-air heat exchanger. The corresponding system matrixes for the heat exchanger (Acoil andBcoil) under these initial conditions are computed as below:

Acoil;Gaẳ0:20 kg=sẳ

0:5327 0 0 0:3072 0 4:4031 0:4860 1:9125 0 0:0011 2:9432 0:0066 0:0491 0:0380 0:2004 0:2803 2

66 64

3 77 75;

Bcoil;Gaẳ0:20 kg=sẳ

0:0720 8:3370 0 0 0

0 0 1:8499 0:4860 32:9884 0 0 0:0011 2:9266 0:1241 0:0491 6:2643 0:0380 0:2004 0:0393 2

66 64

3 77 75;

Acoil;Gaẳ0:22 kg=sẳ

0:5327 0 0 0:3072 0 4:8462 0:4897 2:1346 0 0:0011 3:2368 0:0067 0:0491 0:0393 0:2019 0:2837 2

66 64

3 77 75;

Bcoil;Gaẳ0:22 kg=sẳ

0:0720 9:4744 0 0 0

0 0 2:0313 0:4897 30:5393 0 0 0:0011 3:2000 0:1265 0:0491 6:2643 0:0393 0:2019 0:0076 2

66 64

3 77 75;

Acoil;Gaẳ0:24 kg=sẳ

0:5327 0 0 0:3072 0 5:2890 0:4931 2:3566 0 0:0011 3:5303 0:0067 0:0491 0:0406 0:2033 0:2871 2

66 64

3 77 75;

Bcoil;Gaẳ0:24 kg=sẳ

0:0720 10:8436 0 0 0

0 0 2:2129 0:4931 28:0517 0 0 0:0011 3:5135 0:1306 0:0491 6:0903 0:0406 0:2033 0:0162 2

66 64

3 77 75:

Figure3.7gives the dynamic responses of exit air temperature and humidity to perturbations under different initial airflow rates. The results indicate that the dynamic response characteristics of exit air temperature to perturbations of inlet air temperature and humidity as well as inlet water temperature will not be affected by

initial value of airflow rate, and that to the other kind of disturbance parameters (such as air and waterflow rate) will be affected by initial value of airflow rate. The ampliﬁcation coefﬁcient of response of exit air temperature to the perturbations of

0 0.1 0.2 0.3 0.4 0.5

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Time(s)

Change of response parameters

(Ga)o=0.20kg/s: Response of exit air temperature ( ) (Ga)o=0.22kg/s: Response of exit air temperature ( ) (Ga)o=0.24kg/s: Response of exit air temperature ( ) (Ga)o=0.20kg/s Response of exit air humidity (g/(kg dryair) (Ga)o=0.22kg/s Response of exit air humidity (g/(kg dryair) (Ga)o=0.24kg/s Response of exit air humidity (g/(kg dryair)

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Time (s)

Change of response parameters

(Ga)o=0.20kg/s: Response of exit air temperature () (Ga)o=0.22kg/s: Response of exit air temperature () (Ga)o=0.24kg/s: Response of exit air temperature () (Ga)o=0.20kg/s Response of exit air humidity (g/(kg dryair) (Ga)o=0.22kg/s Response of exit air humidity (g/(kg dryair) (Ga)o=0.24kg/s Response of exit air humidity (g/(kg dryair)

(a) Inlet air temperature has a step increase by 1.0 (b) Inlet air humidity has a step increase by 1.0 g/(kg dryair)

0 0.2 0.4 0.6 0.8 1 1.2

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Time (s)

Change of response parameters

(Ga)o=0.20kg/s: Response of exit air temperature () (Ga)o=0.22kg/s: Response of exit air temperature () (Ga)o=0.24kg/s: Response of exit air temperature () (Ga)o=0.20kg/s Response of exit air humidity (g/(kg dryair) (Ga)o=0.22kg/s Response of exit air humidity (g/(kg dryair) (Ga)o=0.24kg/s Response of exit air humidity (g/(kg dryair)

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Time (s)

Change of response parameters

(Ga)o=0.20kg/s: Response of exit air temperature ( ) (Ga)o=0.22kg/s: Response of exit air temperature ( ) (Ga)o=0.24kg/s: Response of exit air temperature ( ) (Ga)o=0.20kg/s Response of exit air humidity (g/(kg dryair)) (Ga)o=0.22kg/s Response of exit air humidity (g/(kg dryair)) (Ga)o=0.24kg/s Response of exit air humidity (g/(kg dryair))

-1.4 -1.2 -1 -0.8 -0.6 -0.4 -0.2 0

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Time (s)

Change of response parameters

(e) Water flow rate has a step increase by 0.1 kg/s

Fig. 3.7 Dynamic responses of exit air temperature and humidity to perturbations under different initial values of airflow rate.a Inlet air temperature has a step increase by 1.0 °C. bInlet air humidity has a step increase by 1.0 g/(kg dry air).cAirflow rate has a step increase by 0.1 kg/s.

dInlet water temperature has a step increase by 1.0 °C.eWaterflow rate has a step increase by 0.1 kg/s

airflow rate decreases with the initial airflow rate increasing, and so does the ampliﬁcation coefﬁcient of response of exit air humidity to the perturbations of inlet air (or water) temperature andflow rate.

(4) Influence of initial inlet water temperature(tw, E)o

Three initial values of inlet water temperature (i.e., 11.0, 13.0, and 15.0 °C) combined with the other initial conditions including (ta, E)o= 30.0 °C, (Wa,

E)o= 18.0 g/(kg dry air), (Ga)o= 0.20 kg/s,(Gw)o= 0.20 kg/s are used for the dynamic response simulations, and the corresponding system matrixes for the heat exchanger (Acoil,Bcoil) are obtained below:

Acoil;tw;Eẳ11CẳAcoil;tw;Eẳ13C

ẳAcoil;tw;Eẳ15Cẳ

0:5327 0 0 0:3072 0 4:4031 0:4860 1:9125 0 0:0011 2:9432 0:0066 0:0491 0:0380 0:2004 0:2803 2

66 64

3 77 75;

Bcoil;tw;Eẳ11Cẳ

0:0720 11:4094 0 0 0

0 0 1:8499 0:4860 86:2240 0 0 0:0011 2:9266 0:1577 0:0491 10:7885 0:0380 0:2004 0:0202 2

66 64

3 77 75;

Bcoil;tw;Eẳ13Cẳ

0:0720 10:1050 0 0 0

0 0 1:8499 0:4860 66:7030 0 0 0:0011 2:9266 0:1418 0:0491 8:3524 0:0380 0:2004 0:0335 2

66 64

3 77 75;

Bcoil;tw;Eẳ15Cẳ

0:0720 8:3370 0 0 0

0 0 1:8499 0:4860 32:9884 0 0 0:0011 2:9266 0:1241 0:0491 6:2643 0:0380 0:2004 0:0393 2

66 64

3 77 75:

The dynamic responses of exit air temperature and humidity of heat exchanger to perturbations under different initial inlet water temperatures are shown in Fig.3.8.

The results indicate that the dynamic response characteristics of exit air temperature and humidity to the perturbations of inlet air temperature and humidity as well as inlet water temperature will not affected by initial value of inlet water temperature.

However, the initial inlet water temperature will impact the dynamic response characteristics of exit air temperature and humidity when subjected to the perturbations of water and airflow rate. As shown in Fig.3.8c, e, the ampliﬁcation coefﬁcient of response of exit air temperature to the perturbations of water and airflow rate decreases with the increase of initial water temperature.

(5) Influence of initial water flow rate(Gw)o

Likewise, the influences of initial water flow rate on the dynamic response characteristics of exit air temperature and humidity of water-to-air heat exchanger are investigated under different initial water flow rates (i.e., 0.20,0.22 and

-0.05 0.05 0.15 0.25 0.35 0.45 0.55

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Time (s)

Change of response parameters

(tw,E)o=11.0 Response of exit air temperature ( ) (tw,E)o=13.0 Response of exit air temperature ( ) (tw,E)o=15.0 Response of exit air temperature ( ) (tw,E)o=11.0 Response of exit air humidity (g/(kg dryair) (tw,E)o=13.0 Response of exit air humidity (g/(kg dryair) (tw,E)o=15.0 Response of exit air humidity (g/(kg dryair)

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Time (s) Change of response parameters (tw,E)o=11.0 Response of exit air temperature ( )

(tw,E)o=13.0 Response of exit air temperature ( ) (tw,E)o=15.0 Response of exit air temperature ( ) (tw,E)o=11.0 Response of exit air humidity (g/(kg dryair) (tw,E)o=13.0 Response of exit air humidity (g/(kg dryair) (tw,E)o=15.0 Response of exit air humidity (g/(kg dryair)

(a) Inlet air temperature has a step increase by 1.0 (b) Inlet air humidity has a step increase by 1.0 g/(kg dryair)

0 0.5 1 1.5 2 2.5 3 3.5

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Time(s)

Change of response parameters

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Time (s)

Change of response parameters

-3.5 -3 -2.5 -2 -1.5 -1 -0.5 0

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Time (s)

Change of response parameters

(e) Water flow rate has a step increase by 0.1 kg/s

Fig. 3.8 Dynamic responses of exit air temperature and humidity to perturbations under different initial values of inlet water temperature. aInlet air temperature has a step increase by 1.0 °C.

bInlet air humidity has a step increase by 1.0 g/(kg dry air).cAirflow rate has a step increase by 0.1 kg/s.dInlet water temperature has a step increase by 1.0 °C.eWaterflow rate has a step increase by 0.1 kg/s

0.24 kg/s) combined with the other initial conditions including (ta, E)o= 30.0 °C, (tw, E)o= 15.0 °C, (Wa, E)o= 18.0 g/(kg dry air), and (Ga)o= 0.20 kg/s. The corresponding system matrixes for the heat exchanger (Acoil,Bcoil) are computed as follows:

Acoil;Gwẳ0:02 kg=sẳ

0:5789 0 0 0:3237 0 4:4031 0:4860 1:9125 0 0:0011 2:9432 0:0066 0:0517 0:0380 0:2004 0:2803 2

66 64

3 77 75;

Bcoil;Gwẳ0:02 kg=sẳ

0:0720 8:3370 0 0 0

0 0 1:8499 0:4860 32:9884 0 0 0:0011 2:9266 0:1241 0:0491 6:2643 0:0380 0:2004 0:0393 2

66 64

3 77 75;

Acoil;Gwẳ0:02 kg=sẳ

0:5327 0 0 0:3072 0 4:4031 0:4860 1:9125 0 0:0011 2:9432 0:0066 0:0491 0:0380 0:2004 0:2803 2

66 64

3 77 75;

Bcoil;Gwẳ0:022 kg=sẳ

0:0934 8:4136 0 0 0

0 0 1:8499 0:4860 45:8849 0 0 0:0011 2:9266 0:1295 0:0517 5:1678 0:0380 0:2004 0:0379 2

66 64

3 77 75;

Acoil;Gwẳ0:02 kg=sẳ

0:6247 0 0 0:3072 0 4:4031 0:4860 1:9125 0 0:0011 2:9432 0:0066 0:0542 0:0380 0:2004 0:2906 2

66 64

3 77 75;

Bcoil;Gwẳ0:022 kg=sẳ

0:1154 8:3161 0 0 0

0 0 1:8499 0:4860 47:5348 0 0 0:0011 2:9266 0:1343 0:0542 4:0076 0:0380 0:2004 0:0163 2

66 64

3 77 75:

Figure3.9presents the results of dynamic responses of exit air temperature and humidity to different perturbations under different initial water flow rates. From Fig.3.9, we can conclude that the initial waterflow rate makes little influence on the dynamic response characteristics of exit air temperature and humidity when subjected to the disturbances of inlet air temperature and humidity, but the situation is different when subjected to the disturbances of water and airflow rate as well as inlet water temperature. The coefﬁcient of response of exit air temperature to the

perturbations of airflow rate and inlet water temperature increases with the increase of initial waterflow rate, and it is opposite for that to the perturbations of waterflow rate itself.

-0.05 0.05 0.15 0.25 0.35 0.45 0.55

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Time (s)

Change of response parameters

(Gw)o=0.20kg/s Response of exit air temperature ( ) (Gw)o=0.22kg/s Response of exit air temperature ( ) (Gw)o=0.24kg/s Response of exit air temperature ( ) (Gw)o=0.20kg/s Response of exit air humidity (g/(kg dryair) (Gw)o=0.22kg/s Response of exit air humidity (g/(kg dryair) (Gw)o=0.24kg/s Response of exit air humidity (g/(kg dryair)

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Time (s)

Change of response parameters (Gw)o=0.20kg/s Response of exit air temperature ( ) (Gw)o=0.22kg/s Response of exit air temperature ( ) (Gw)o=0.24kg/s Response of exit air temperature ( ) (Gw)o=0.20kg/s Response of exit air humidity (g/(kg dryair) (Gw)o=0.22kg/s Response of exit air humidity (g/(kg dryair) (Gw)o=0.24kg/s Response of exit air humidity (g/(kg dryair)

(a) Inlet air temperature has a step increase by 1.0 (b) Inlet air humidity has a step increase by 1.0 g/(kg dryair)

0 0.2 0.4 0.6 0.8 1 1.2

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Time (s)

Change of response parameters

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Time (s)

Change of response parameters

-1.6 -1.4 -1.2 -1 -0.8 -0.6 -0.4 -0.2 0

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Time (s)

Change of response parameters

(e) Water flow rate has a step increase by 0.1 kg/s

Fig. 3.9 Dynamic responses of exit air temperature and humidity to perturbations under different initial values of waterflow rate.aInlet air temperature has a step increase by 1.0 °C.bInlet air humidity has a step increase by 1.0 g/(kg dry air).cAirflow rate has a step increase by 0.1 kg/s.

dInlet water temperature has a step increase by 1.0 °C.eWaterflow rate has a step increase by 0.1 kg/s

Virtual Calibration for HVAC Sensors

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