Upload
mervin-fox
View
217
Download
4
Embed Size (px)
Citation preview
Application of QuickField SoftwareApplication of QuickField Software
to Heat Transfer Problemsto Heat Transfer Problems
i
jk
By Dr. Evgeni Volpov
Basic Formulations for GIS HT model Basic Formulations for GIS HT model
Boundary Boundary ConditionsConditions
11. . T(S) = TT(S) = T0 0 Const Const TemperatureTemperature
T(S) = TT(S) = T00 + k.S Linear Temp. + k.S Linear Temp.
22. . FFnn = -q = -qs s FluxFlux
FFnn(+) - F(+) - Fnn(-) = -q(-) = -qss 3. 3. FFnn = a(T - T = a(T - T00) ) ConvectionConvection
a - film coefficient T0 – temperature of contacting medium
4. FFnn = b.K = b.Ksbsb(T(T44 - T - T0044) Radiation) Radiation
Ksb - Stephan-Boltzmann constant;
b - emissivity coefficient
Classical Heat Transfer Classical Heat Transfer EquationsEquations
Boundary conditions & domain characterization
Volume element
Surface element
Point-Source element
Joule losses distribution at central conductor1000 A
1920 W/m3
500 W/m3
Electric Field distribution in GIS compartment
100 kV AC
enclosure
2.3 MV/m
epoxy spacer
53 C
31 C
HV conductor current 1000 A
P SF6 = 0.6 MPa
Air
Spacer deformation under SF6 pressure
epoxy spacer
enclosure
Coupling Problems solution for SF6 GIS 170 kVCoupling Problems solution for SF6 GIS 170 kV
Thermo-static field mapping in GIS compartment
SF6 GIS HT Model Parameters1. SF6 Thermal Conductivity g = 0.0136 W/m.K
2. Air Thermal Conductivity a = 0.026 W/m.K
3. Epoxy Thermal Conductivity e (0.3-0.6) W/m.K
4. Aluminum Thermal Conductivity al (140-220)
W/m.K
5. Copper Thermal Conductivity cu = 380 W/m.K
6. Convection Parameters:6.1. Internal SF6 space:
k = 0.133(Gr.Pr)0.28 (1.2 - 6.0)
103 < Gr.Pr < 106 (for SF6 GIS)
6.2. External Air space:
ac (2-10) W/K.m2 ; T0 (20-25C)
7. Radiation Parameters:
equivalent emissivity coefficient: be (0.01 - 0.6)
GIS Geometric Model examples
2 0 0 0
R 0R 1R 2
Symmetry Axis
Air layer
R0R1R2
L > 5 0 0 0
(a)L
L
(b)
Hot-spot
- - rr rr - Z - ZGeometric Models & results presentation
Geometric Models & results presentation
Thermal Field mapping for BB model 1.2 m T0 (ambient) =
20C
28.8 C29.8 C
64 C 60.1 C
64 C 54.0 C
28.1 C29.7 C
TemperatureT (K)
337.0
332.6
328.2
323.8
319.4
315.0
310.6
306.2
301.8
297.4
293.0
Conductivity only23.0 C23.8 C
64 C 63.0 C
1.2 m
Hot-spot Flange
1000 A
1000 A
1000 A
Conductivity + convection
Conductivity + convection+ radiation
TemperatureT (K)
337.0
332.6
328.2
323.8
319.4
315.0
310.6
306.2
301.8
297.4
293.0
29.1 C31.0 C
64 C 54.1 C
23.1 C23.9 C
64 C 62.6 C
26.8 C29.5 C
64 C 43.0 C
2.3 m
Conductivity + convection
Conductivity + convection+ radiation
Conductivity only
Flange
T0 (ambient) = 20C
1000 A
1000 A
1000 A
Thermal Field mapping for BB model 2.3 m
Hot-spot
0
1
2
3
4
5
6
60 70 80 90 100 110 120
Tmax C
T C
BB length 2 m
BB length 1 m
Including radiation
Enclosure overheating as a function of Hot-spot temperature
Hot-spot temperature
Tem
pera
ture
dro
p al
ong
the
encl
osur
e
10
20
30
40
50
60
0.5 1.0 2.0 3.0 4.0 5.0
L [m]
Max t
em
pera
ture
on t
he
en
closu
re
Enclosure length
Tmax C
50 kW/m3
100 kW/m3
Specific Joule loss in the damaged contact
R = 100 I = 1000 AV = 1000 cm3
Enclosure temperature with no damaged contact
T0 (ambient) = 20C
Enclosure overheating as a function of the BB length
Conductivity + convectionConductivity + convection+
radiation
TemperatureT (K)
96.40
88.76
81.12
73.48
65.84
58.20
50.56
42.92
35.28
27.64
20.00
T CT C
3 2.6 10 5 sec
2.3 m
Q2 = 2 kW/m3Q1 = 100 kW/m3
HT Transients for BB model
g k = 0.10
Conductivity + convection
Steady State distribution
Initial distribution
1000 A
0 A
T0 (ambient) = 20C