Influence of insulation paper on the hot spot temperature of oil-immersed transformer winding

2021 ◽  
pp. 2140021
Author(s):  
Chuan Luo ◽  
Zhen-Gang Zhao ◽  
Yu-Yuan Wang ◽  
Ke Liang ◽  
Jia-Hong Zhang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Hot Spot ◽  
Transformer Oil ◽  
Heat Diffusion ◽  
Normal Operation ◽  
Measured Temperature ◽  
Conduction Model ◽  
Transfer Resistance ◽  
Actual Environment ◽  
Spot Temperature

The oil-immersed transformer is a crucial piece of equipment in the power system. Operating at the specified temperature is necessary to ensure the normal operation of the transformer. The insulation paper on the winding surface has a significant impact on the actual temperature of the transformers, which is often overlooked by researchers. The one-dimensional steady-state heat conduction model of the transformer is established by analyzing the heat diffusion process of winding to transformer oil. Atomic force microscope was used to observe the microsurface structure of insulation paper and copper. According to the experiment, the heat transfer resistance in the series process of heat transfer at [Formula: see text]C is 0.0138 m2 K/W. Space thermal circuit model of transformer is established by thermoelectricity analogy method, and the simulation circuit is optimized according to the boundary conditions set up in the actual environment. The results show that the error of the hot spot temperature is closer to the measured temperature and decreases by 2.5% when considering the thermal resistance of insulation paper.

Modeling of Localized Heating Effect in Sub-Micron Silicon Transistors

2003 ◽  
Author(s):  
Keivan Etessam-Yazdani ◽  
Sadegh M. Sadeghipour ◽  
Mehdi Asheghi
Keyword(s):  
Transport Equation ◽  
Hot Spot ◽  
Boltzmann Transport Equation ◽  
Phonon Transport ◽  
Heat Diffusion ◽  
Normal Operation ◽  
Heating Effect ◽  
Boltzmann Transport ◽  
Heat Diffusion Equation ◽  
Localized Heating

The performance and reliability of sub-micron semiconductor transistors demands accurate modeling of electron and phonon transport at nanoscales. The continued downscaling of the critical dimensions, introduces hotspots, inside transistors, with dimensions much smaller than phonon mean free path. This phenomenon, known as localized heating effect, results in a relatively high temperature at the hotspot that cannot be predicted using heat diffusion equation. While the contribution of the localized heating effect to the total device thermal resistance is significant during the normal operation of transistors, it has even greater implications for the thermoelectrical behavior of the device during an electrostatic discharge (ESD) event. The Boltzmann transport equation (BTE) can be used to capture the ballistic phonon transport in the vicinity of a hot spot but many of the existing solutions are limited to the one-dimensional and simple geometry configurations. We report our initial progress in solving the two dimensional Boltzmann transport equation for a hot spot in an infinite media (silicon) with constant temperature boundary condition and uniform heat generation configuration.

Constructal Placement of Discrete Heat Sources With Different Lengths in Vertical Ducts Under Natural and Mixed Convection

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Bugra Sarper ◽  
Mehmet Saglam ◽  
Orhan Aydin
Keyword(s):  
Heat Transfer ◽  
Mixed Convection ◽  
Hot Spot ◽  
Experimental Studies ◽  
Vertical Channel ◽  
Working Fluid ◽  
Heat Sources ◽  
Ansys Fluent ◽  
Cooling Performance ◽  
Spot Temperature

In this study, convective heat transfer in a discretely heated parallel-plate vertical channel which simulates an IC package is investigated experimentally and numerically. Both natural and mixed convection cases are considered. The primary focus of the study is on determining optimum relative lengths of the heat sources in order to reduce the hot spot temperature and to maximize heat transfer from the sources to air. Various values of the length ratio and the modified Grashof number (for the natural convection case)/the Richardson number (for the mixed convection case) are examined. Conductive and radiative heat transfer is included in the analysis while air is used as the working fluid. Surface temperatures of the heat sources and the channel walls are measured in the experimental study. The numerical studies are performed using a commercial CFD code, ANSYS fluent. The variations of surface temperature, hot spot temperature, Nusselt number, and global conductance of the system are obtained for varying values of the working parameters. From the experimental studies, it is showed that the use of identical heat sources reduces the overall cooling performance both in natural and mixed convection. However, relatively decreasing heat sources lengths provides better cooling performance.

Research of the Temperature Field Distribution Based on FVM for Oil-Immersed Transformer

2014 ◽  
Vol 1079-1080 ◽  
pp. 510-514
Author(s):  
Yong Qiang Wang ◽  
Jie He ◽  
Lun Ma ◽  
Liu Wang ◽  
Ying Ying Sun ◽  
...  
Keyword(s):  
Temperature Field ◽  
High Temperature ◽  
Temperature Distribution ◽  
Field Distribution ◽  
Hot Spot ◽  
Load Capacity ◽  
Normal Operation ◽  
Internal Temperature ◽  
Temperature Field Distribution ◽  
Spot Temperature

Thehottest spot temperature (HST) of windings of oil-immersed transformer is animportant factor that affects load capacity and operation life of transformer,and is closely related to the transformer load, top oil and environmenttemperature. HST, when operating at high temperature and overload, may lead totransformer failure which will affect the normal operation of the power system.In order to calculate the transformer hot spot temperature accurately, we takea 33MVA-500KV transformer as an example, and establish a three dimensionalmodel, get its internal temperature distribution based on Fluent simulationsoftware. At last, we comparative and analysis the accuracy of FVM calculation andIEEE guidelines recommend model combined with online monitored values. Theresults show that the FVM method with higher accuracy relative to the IEEEguidelines model, proved that using the FVM can accurately calculate the HST ofoil-immersed transformer.

Heat Transfer Enhancement From a Blade Tip-Cap Using Metal Foams

2012 ◽  
Vol 134 (11) ◽  
Author(s):  
Owen Sengstock ◽  
Kamel Hooman
Keyword(s):  
Heat Transfer ◽  
Hot Spot ◽  
Metal Foams ◽  
Plate Temperature ◽  
Pin Fin ◽  
Heat Transfer Augmentation ◽  
Smooth Channel ◽  
Pin Fins ◽  
Blade Tip ◽  
Spot Temperature

3D numerical results are presented to compare the heat transfer augmentation from a plate by using pin fins and metal foams. It is observed that maximizing the inlet velocity and pores per inch maximizes the overall heat transfer rate. The thickness of the foam layer has minimal effect on overall rates of heat transfer, but great effect on the maximum plate temperature. It has been shown that an optimum thickness exists which minimizes the hot spot temperature. Hot spots are generally located in the corners where velocities are the lowest. While the pressure drop remains almost unaltered, the heat transfer increases by 146% and 12% compared with a smooth channel and the optimal pin-fin data available in the literature, respectively. Interestingly, the additional mass of the foams, to achieve this performance, is approximately one-quarter of the best pin-fin sink quoted above.

scholarly journals Effect of Loads on Temperature Distribution Characteristics of Oil-Immersed Transformer Winding

2021 ◽  
Author(s):  
Zhengang Zhao ◽  
Zhangnan Jiang ◽  
Yang Li ◽  
Chuan Li ◽  
Dacheng Zhang
Keyword(s):  
Temperature Distribution ◽  
Hot Spots ◽  
Hot Spot ◽  
Transformer Oil ◽  
Distribution Characteristics ◽  
Thermal Circuit ◽  
Transformer Winding ◽  
Overload Capacity ◽  
The Impact ◽  
Spot Temperature

The temperature of the hot-spots on windings is a crucial factor that can limit the overload capacity of the transformer. Few studies consider the impact of the load on the hot-spot when studying the hot-spot temperature and its location. In this paper, a thermal circuit model based on the thermoelectric analogy method is built to simulate the transformer winding and transformer oil temperature distribution. The hot-spot temperature and its location under different loads are qualitatively analyzed, and the hot-spot location is analyzed and compared to the experimental results. The results show that the hot-spot position on the winding under the rated power appears at 85.88% of the winding height, and the hot-spot position of the winding moves down by 5% in turn at 1.3, 1.48, and 1.73 times the rated power respectively.

Thermal Analyzing of Disc Type Winding With Directed Oil Flow

2004 ◽  
Author(s):  
Seyyed Mehdi Peste ◽  
Mehdi Abloo
Keyword(s):  
Heat Transfer ◽  
Hot Spot ◽  
Iterative Solution ◽  
Oil Viscosity ◽  
Temperature Dependent ◽  
Local Circulation ◽  
Flow Paths ◽  
Oil Flow ◽  
Oil Density ◽  
Spot Temperature

In this paper, a model of a disc type winding for a transformer with directed oil flow is presented which utilizes a network of oil flow paths. Along each path segment, oil velocities and temperature rises are computed. The model includes temperature dependent oil density, resistivity, and oil viscosity and temperature and velocity dependent heat transfer and friction coefficients. Because of the non-linearity, an iterative solution is necessary. Temperature and oil velocities are computed and compared with experiment values. From this, the average winding temperature rise and the hot spot temperature can be determined. The model assumes the oil flows in definite paths and ignores local circulation, since we assume the oil flow is guided by means of oil flow washers, this assumption should be fairly accurate. The disc type winding is assumed to be subdivided into directed oil flow cooling paths.

scholarly journals Analysis of the Properties of Fractional Heat Conduction in Porous Electrodes of Lithium-Ion Batteries

Entropy ◽  
2021 ◽  
Vol 23 (2) ◽  
pp. 195
Author(s):  
Xin Lu ◽  
Hui Li ◽  
Ning Chen
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Lithium Ion Batteries ◽  
Lithium Ion ◽  
Porous Electrodes ◽  
Transient Temperature ◽  
Measured Temperature ◽  
Conduction Model ◽  
Heat Conduction Model ◽  
Fractional Heat Conduction

Research on the heat transfer characteristics of lithium-ion batteries is of great significance to the thermal management system of electric vehicles. The electrodes of lithium-ion batteries are composed of porous materials, and thus the heat conduction of the battery is not a standard form of diffusion. The traditional heat conduction model is not suitable for lithium-ion batteries. In this paper, a fractional heat conduction model is used to study the heat transfer properties of lithium-ion batteries. Firstly, the heat conduction model of the battery is established based on the fractional calculus theory. Then, the temperature characteristic test was carried out to collect the temperature of the battery in various operating environments. Finally, the temperature calculated by the fractional heat conduction model was compared with the measured temperature. The results show that the accuracy of fractional heat conduction model is higher than that of traditional heat conduction model. The fractional heat conduction model can well simulate the transient temperature field of the battery. The fractional heat conduction model can be used to monitor the temperature of the battery, so as to ensure the safety and stability of the battery performance.

Analysis of the Heat Transfer Coefficients on the Top of a Marine Diesel Piston Using the Inverse Heat Conduction Method

2011 ◽  
Vol 291-294 ◽  
pp. 1657-1661 ◽  
Author(s):  
Tao He ◽  
Xi Qun Lu ◽  
Yi Bin Guo
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Optimization Problem ◽  
Heat Conduction Problem ◽  
Inverse Heat Conduction Problem ◽  
Measured Temperature ◽  
Inverse Heat Conduction ◽  
Transfer Coefficients ◽  
Conduction Model ◽  
Marine Diesel

An efficient method utilizing the concept of inverse heat conduction is presented for the thermal analysis of pistons based on application to the piston head of a marine diesel engine. An inverse heat conduction problem is established in the form of an optimization problem. In the optimization problem, the convection heat transfer coefficient（HTC）on the top side of the piston is defined as the design variable, while the error between the measured and analysed temperatures is defined as objective function. For the optimization, an axi-symmetrical finite element conduction model is presented. The optimum distribution of the HTC at the top side of piston is successfully determined through a numerical implementation. The temperature obtained via an analysis using the optimum HTC is compared with the measured temperature, and reasonable agreement is obtained. The present method can be effectively utilized to analyze the temperature distribution of engine pistons.

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