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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.
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Application of QuickField Softwareto 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) = T0 Const Temperature T(S) = T0 + k.S Linear Temp. 2. Fn = -qs Flux Fn(+) - Fn(-) = -qs 3. Fn = a(T - T0) Convection a - film coefficient T0– temperature of contacting medium 4. Fn = b.Ksb(T4 - T04) Radiation Ksb - Stephan-Boltzmann constant; b - emissivity coefficient
Boundary conditions & domain characterization Surface element Volume element Point-Source element
Coupling Problems solution for SF6 GIS 170 kV enclosure 1920 W/m3 epoxy spacer 500 W/m3 2.3 MV/m Joule losses distribution at central conductor 1000 A 100 kV AC Electric Field distribution in GIS compartment 31 C enclosure P SF6 = 0.6 MPa epoxy spacer Air Spacer deformation under SF6 pressure 53 C HV conductor current 1000 A Thermo-static field mapping in GIS compartment
SF6 GIS HT Model Parameters 1. SF6 Thermal Conductivityg = 0.0136 W/m.K 2. Air Thermal Conductivitya = 0.026 W/m.K 3. Epoxy Thermal Conductivitye (0.3-0.6) W/m.K 4. Aluminum Thermal Conductivityal (140-220) W/m.K 5. Copper Thermal Conductivitycu = 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 Symmetry Axis (a) L Hot-spot Air layer L (b)
Geometric Models & results presentation r - Z - r
Thermal Field mapping for BB model 1.2 m T0 (ambient) = 20C Conductivity only 23.8 C 23.0 C 1000 A 64 C 63.0 C Hot-spot Flange Conductivity + convection 29.8C 28.8C 1000 A 64 C 60.1 C Conductivity + convection+ radiation 29.7 C 28.1 C 1000 A 64 C 54.0 C 1.2 m
Thermal Field mapping for BB model 2.3 m T0 (ambient) = 20C Conductivity only 23.9 C 23.1 C 1000 A 64 C 62.6 C Hot-spot Conductivity + convection 31.0 C 29.1 C 1000 A 64 C 54.1 C Flange Conductivity + convection+ radiation 29.5 C 26.8 C 1000 A 64 C 43.0 C 2.3 m
Enclosure overheating as a function of Hot-spot temperature T C Temperature drop along the enclosure BB length 1 m Hot-spot temperature Tmax C BB length 2 m Including radiation
Enclosure overheating as a function of the BB length R = 100 I = 1000 A V = 1000 cm3 Specific Joule loss in the damaged contact Tmax C 100 kW/m3 50 kW/m3 Max temperature on the enclosure Enclosure temperature with no damaged contact Enclosure length L [m] T0 (ambient) = 20C Conductivity + convection Conductivity + convection+ radiation
HT Transients for BB model T C T0 (ambient) = 20C 2.3 m 0 A Initial distribution 3 2.6 10 5 sec Q2 = 2 kW/m3 Q1 = 100 kW/m3 1000 A Steady State distribution T C Conductivity + convection g k = 0.10