application of quickfield software to heat transfer problems
DESCRIPTION
Application of QuickField Software to Heat Transfer Problems. j. k. i. By Dr. Evgeni Volpov. Basic Formulations for GIS HT model. Classical Heat Transfer Equations. Boundary Conditions. 1. T(S) = T 0 Const Temperature T(S) = T 0 + k.S Linear Temp. - PowerPoint PPT PresentationTRANSCRIPT
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