Error Analysis of Transformer Hot Spot Temperature Measurement

According to the national standard GB/T 1094.7-2008, the method of hot spot measurement of oil-immersed transformer is used to place several temperature sensors inside the gasket within the predicted hot spot position to measure the temperature of winding transformer. The highest temperature measured is regarded as the hot spot temperature of transformer. Since the winding and gasket are bad conductors of heat, there exists certain temperature difference between the gasket and the hot spot temperature of the winding. In order to ensure safe operation of transformer, the thermal environment of temperature measuring point is analyzed and the discrete equation of boundary node is established. The parameters are set according to the heat transfer mode of the oil-immersed transformer and the temperature characteristics of each heat transfer node is analyzed. Gauss-Seidel Iteration method is used to calculate the theoretical value of the measuring point of the oil-immersed transformer and the heat transfer model of the measuring point is established for further analysis. The experimental platform of the oil-immersed transformer simulator is established according to the method described in the national standard and used to measure the hot spot temperature and winding surface temperature. The results show that when the winding temperature is 77 ℃, the heat transfer model of the temperature measuring point is 74.7 ℃ and the experimental temperature of the temperature measuring point is 74.9 ℃. The error between theoretical calculation temperature and experimental temperature is 0.2. As the temperature of the experiment increases, the temperature difference between the temperature point and the winding temperature gradually increases, and the maximum absolute error is 2.1 ℃.

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Modeling the Winding Hot-Spot Temperature and Aging of Enclosed Vault Transformers using a Physics-Based Heat Transfer Model

2020 IEEE/PES Transmission and Distribution Conference and Exposition (T&D) ◽

10.1109/td39804.2020.9299993 ◽

2020 ◽

Author(s):

Poorva Bedge ◽

James Spaulding ◽

Daniel Zimmerle ◽

Gerald Duggan

Keyword(s):

Heat Transfer ◽

Hot Spot ◽

Heat Transfer Model ◽

Transfer Model ◽

Spot Temperature

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Heating and Ignition of Metal Particles in the Transition Heat Transfer Regime

Journal of Heat Transfer ◽

10.1115/1.2945881 ◽

2008 ◽

Vol 130 (10) ◽

Cited By ~ 27

Author(s):

Salil Mohan ◽

Mikhaylo A. Trunov ◽

Edward L. Dreizin

Keyword(s):

Heat Transfer ◽

Temperature Difference ◽

Particle Diameter ◽

Accommodation Coefficient ◽

Heat Transfer Model ◽

Heat Transfer Analysis ◽

Transfer Model ◽

Metallic Particles ◽

The Continuum ◽

Transition Heat

This paper considers the heating and ignition of small metallic particles in hot gases for a range of Knudsen numbers, for which the continuum description of heat transfer is not valid. Modified Fuchs’ model for the transition heat transfer analysis was adapted to treat diatomic gas with properties changing as a function of temperature. The dimensionless heat transfer coefficient, Nusselt number, was calculated as a function of the particle diameter for the transition heat transfer regime. Heat transfer rates in the transition regime are somewhat different from one another for the cases of particle heating and cooling while the absolute values of the particle-gas temperature difference are the same. This effect does not exist for the continuum heat transfer model. It is observed that the applicability of the continuum heat transfer model for particles of different sizes depends on pressure and particle-air temperature difference. For example, for particles at 300K heated in air at 2000K, the continuum heat transfer model can be used for particle diameters greater than 10μm and 1μm at the pressures of 1bar and 10bars, respectively. Transition heat transfer model must be used for the analysis of heat transfer for nanosized particles. For calculating the ignition delay, the continuum model remains useful for particle diameters greater than 18μm and 2μm for 1bar and 10bars, respectively. The sensitivity of the transition heat transfer model to the accommodation coefficient is evaluated. It is found that for metallic particles, the accommodation coefficient has a relatively weak effect on the heat transfer rate.

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RADIATIVE HEAT TRANSFER MODEL IN ARBITRARY ENCLOSURES BY RAY-TRACING

Proceedings of the Second International Symposium on Radiation Transfer ◽

10.1615/ichmt.1997.intsymliqtwophaseflowtranspphenchtradtransfproc.60 ◽

1997 ◽

Cited By ~ 2

Author(s):

Wen Cai

Keyword(s):

Heat Transfer ◽

Ray Tracing ◽

Radiative Heat Transfer ◽

Radiative Heat ◽

Heat Transfer Model ◽

Transfer Model

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A Heat Transfer Model for Concentrating Silicon Solar Cells in a Spectrally Splitting Hybrid Receiver

Proceedings of the 15th International Heat Transfer Conference ◽

10.1615/ihtc15.sol.009067 ◽

2014 ◽

Cited By ~ 1

Author(s):

Ahmad Mojiri ◽

Cameron Stanley ◽

Elizabeth Thomsen ◽

Vernie Everett ◽

Andrew Blakers ◽

...

Keyword(s):

Heat Transfer ◽

Solar Cells ◽

Heat Transfer Model ◽

Silicon Solar Cells ◽

Transfer Model

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Theoretical Post-Dryout Heat Transfer Model

International Journal of Computational Physics Series ◽

10.29167/a1i1p142-150 ◽

2018 ◽

Vol 1 (1) ◽

pp. 142-150

Author(s):

Murat Tunc ◽

Ayse Nur Esen ◽

Doruk Sen ◽

Ahmet Karakas

Keyword(s):

Heat Transfer ◽

Droplet Diameter ◽

Heat Transfer Model ◽

Transfer Model ◽

Operating Pressure ◽

Vertical Pipe ◽

Two Phase ◽

Experimental Values ◽

Reactor Operating ◽

Coolant System

A theoretical post-dryout heat transfer model is developed for two-phase dispersed flow, one-dimensional vertical pipe in a post-CHF regime. Because of the presence of average droplet diameter lower bound in a two-phase sparse flow. Droplet diameter is also calculated. Obtained results are compared with experimental values. Experimental data is used two-phase flow steam-water in VVER-1200, reactor coolant system, reactor operating pressure is 16.2 MPa. On heater rod surface, dryout was detected as a result of jumping increase of the heater rod surface temperature. Results obtained display lower droplet dimensions than the experimentally obtained values.

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