Calculation of Thermal Dynamic Characteristics …
113
5.444
4.811
0.014
74.9
66.1
0.043
16.24
4.332
4.811
0.015
59.5
66.1
0.048
17.14
3.918
4.811
0.021
53.9
66.1
0.068
16.22
internal thermal
admittance
external thermal
admittance
periodical thermal
transmittance
thermal capacity of the
wall surface at the
internal side
thermal capacity of the
wall surface at the
external side
decrement factor
factor of the
temperature delay
wall 1
wall 2
wall 3
Y 11 [W/m 2 K]
Y 22 [W/m 2 K]
Y 12 [W/m 2 K]
k 1 [kJ/m 2 K]
f [ ]
τ 12 [h]
k 2 [kJ/m 2 K]
Fig. 2 Dynamic thermal characteristics of walls 1–3
The factor of the amplitude decrease of the external temperature oscillation, that
is, the decrement factor, is the highest for wall 3 and lowest for wall 1.
The delay factor for variation of the outside temperature on wall 1 is slightly
different from the same value for wall 3, while for wall 2 the delay factor is slightly
higher.
The dynamic characteristics for walls 4–6, determined based on Eqs. (3)–(12),
are given in Fig. 3. Figure 3 shows internal and external thermal admittance, periodic
thermal transmittance and thermal capacity of the inner and outer wall surfaces, the
decrement factor and the temperature delay factor for walls 4–6.
Based on results shown in Fig. 3, it can be seen that the phase delay on the inside
of the wall, i.e. internal admittance, is different for different types of walls, while the
phase delay on the exterior of the wall, i.e. the external admittance, is equal for all
the walls. This means that the walls respond to changes on outside temperature at
different rates.
When values of the phase shift on the inside of the wall, for walls with and without
vegetation cover are compared, it can be seen that those values are identical. On the
other hand, values for the phase delay on the outside of the wall are almost four
5.444
1.292
0.004
74.9
17.8
0.013
18.18
4.332
1.292
0.004
59.5
17.7
0.015
19.09
3.918
1.292
0.006
53.8
17.8
0.021
18.17
internal thermal
admittance
external thermal
admittance
periodical thermal
transmittance
thermal capacity of the
wall surface at the
internal side
thermal capacity of the
wall surface at the
external side
decrement factor
factor of the
temperature delay
wall 4
wall 5
wall 6
Y 11 [W/m 2 K]
Y 22 [W/m 2 K]
Y 12 [W/m 2 K]
k 1 [kJ/m 2 K]
f [ ]
τ 12 [h]
k 2 [kJ/m 2 K]
Fig. 3 Dynamic thermal characteristics of walls 4–6
113
5.444
4.811
0.014
74.9
66.1
0.043
16.24
4.332
4.811
0.015
59.5
66.1
0.048
17.14
3.918
4.811
0.021
53.9
66.1
0.068
16.22
internal thermal
admittance
external thermal
admittance
periodical thermal
transmittance
thermal capacity of the
wall surface at the
internal side
thermal capacity of the
wall surface at the
external side
decrement factor
factor of the
temperature delay
wall 1
wall 2
wall 3
Y 11 [W/m 2 K]
Y 22 [W/m 2 K]
Y 12 [W/m 2 K]
k 1 [kJ/m 2 K]
f [ ]
τ 12 [h]
k 2 [kJ/m 2 K]
Fig. 2 Dynamic thermal characteristics of walls 1–3
The factor of the amplitude decrease of the external temperature oscillation, that
is, the decrement factor, is the highest for wall 3 and lowest for wall 1.
The delay factor for variation of the outside temperature on wall 1 is slightly
different from the same value for wall 3, while for wall 2 the delay factor is slightly
higher.
The dynamic characteristics for walls 4–6, determined based on Eqs. (3)–(12),
are given in Fig. 3. Figure 3 shows internal and external thermal admittance, periodic
thermal transmittance and thermal capacity of the inner and outer wall surfaces, the
decrement factor and the temperature delay factor for walls 4–6.
Based on results shown in Fig. 3, it can be seen that the phase delay on the inside
of the wall, i.e. internal admittance, is different for different types of walls, while the
phase delay on the exterior of the wall, i.e. the external admittance, is equal for all
the walls. This means that the walls respond to changes on outside temperature at
different rates.
When values of the phase shift on the inside of the wall, for walls with and without
vegetation cover are compared, it can be seen that those values are identical. On the
other hand, values for the phase delay on the outside of the wall are almost four
5.444
1.292
0.004
74.9
17.8
0.013
18.18
4.332
1.292
0.004
59.5
17.7
0.015
19.09
3.918
1.292
0.006
53.8
17.8
0.021
18.17
internal thermal
admittance
external thermal
admittance
periodical thermal
transmittance
thermal capacity of the
wall surface at the
internal side
thermal capacity of the
wall surface at the
external side
decrement factor
factor of the
temperature delay
wall 4
wall 5
wall 6
Y 11 [W/m 2 K]
Y 22 [W/m 2 K]
Y 12 [W/m 2 K]
k 1 [kJ/m 2 K]
f [ ]
τ 12 [h]
k 2 [kJ/m 2 K]
Fig. 3 Dynamic thermal characteristics of walls 4–6