Research on Heat Transfer by Fluid in Winding Region of Power Transformer

In this paper, a model of the winding area for a normal working oil-immersed power (180MVA, 220kV) was built to conduct the simulation analysis for heat transfer of fluid field. Based on the fundamental mechanisms of fluid mechanics, limited volume method was used to build the model of the winding area of the power transformer. The effect of the oil input velocity, the amount and the position of oil baffle plate were concluded. The reasonable method to control the temperature was purposed by analyzing the heat-transfer properties for different conditions. When the initial oil velocity was 0.3-0.4 m/s during forced oil circulation, the best heat transfer was achieved. For the natural oil circulation, inserting 3 oil baffle plates at the higher temperature winding ends, when the number of the next two oil baffle plates is 7, the heat delivery effect is best.

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Transient free convection within air-filled hemispherical enclosures. Nu-Ra-Fo relationships for isothermal and inclined disk with dome oriented upwards

International Journal of Numerical Methods for Heat &amp Fluid Flow ◽

10.1108/hff-04-2014-0112 ◽

2015 ◽

Vol 25 (3) ◽

pp. 629-638 ◽

Cited By ~ 5

Author(s):

Abderrahmane Baïri

Keyword(s):

Heat Transfer ◽

Convective Heat Transfer ◽

Convective Heat ◽

Convection Heat Transfer ◽

Numerical Approach ◽

Content Type ◽

Turbulent Natural Convection ◽

Higher Temperature ◽

Fourier Type ◽

Volume Method

Purpose – Nusselt-Rayleigh-Fourier type correlations are proposed to quantify the temporal evolution of convective heat transfer occurring within air-filled hemispherical enclosures whose disk, initially at ambient temperature, is suddenly maintained at a higher temperature. The temperature difference imposed between this hot wall and the isothermal cold dome involves Rayleigh number varying between 104 and 2.55×1012. Depending on the application, the disk can be inclined with respect to the horizontal plane by an angle varying between 0° (horizontal disk) and 90° (vertical disk) in steps of 15°. The paper aims to discuss these issues. Design/methodology/approach – The results are obtained by means of a numerical approach based on the finite volume method. The proposed correlations linked to the steady state Nusselt-Rayleigh internships recently published, concerning the same inclination angle and Rayleigh ranges. Findings – The statistical analysis of a large number of calculations leads to reliable results covering laminar, transitional and turbulent natural convection heat transfer zones. Practical implications – The proposed relationships can be applied in several engineering fields such as nuclear technology, solar energy, security and safety electronics, building, domotics or aeronautics. Originality/value – The new relationships proposed in this paper provide important information on the evolution of convective heat transfer during the transient regime.

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Fans arrangement analysis in oil forced air natural cooling method of power transformer radiator

Proceedings of the Institution of Mechanical Engineers Part A Journal of Power and Energy ◽

10.1177/0957650920962249 ◽

2020 ◽

pp. 095765092096224

Author(s):

Mohammad Ali Taghikhani ◽

Mohammad Reza Afshar

Keyword(s):

Heat Transfer ◽

Power Transformer ◽

Power Transformers ◽

Vertical Position ◽

Vertical Mode ◽

Cooling Method ◽

First Case ◽

Cooling Fans ◽

Natural Oil ◽

Forced Air

The cooling of radiators in power transformers employing natural oil-air forced method is the purpose of this study. Two modes used for cooling fans, namely vertical and horizontal placement, will be compared as well. Four sets of radiators have been studied in this research, and in each set, 14 fins and three fans with a diameter of half a meter have been used. The fans will be arranged such that three of them will be placed under the radiator (in vertical position) in the first case, while in the second case, they will be located in one side of the radiator (in horizontal position). The results derived from the comparisons indicate the superiority of the horizontal mode in heat transfer against the vertical mode. Furthermore, it is notable that if the internal fan is disconnected, the cooling can be enhanced with the help of some existing points in the vertical mode. The improvement in heat transfer rate can be observed through locating the vertical fans optimally, once compared to the horizontal placement. The lower reliability of the vertical mode can be detected once the side fans are disconnected, while in any cases, the heat transfer superiority is achievable for horizontal mode. That is because, the disconnection of one of the fans, leads to the negligence of the radiators major parts in the vertical mode.

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ANALYSIS OF THE TEMPERATURE FIELD IN A MOLD CAVITY FOR POLYMER INJECTION PROCESS

DYNA INGENIERIA E INDUSTRIA ◽

10.6036/10030 ◽

2022 ◽

Vol 97 (1) ◽

pp. 10-10

Author(s):

ADRIAN JOSE BENITEZ LOZANO ◽

CARLOS ANDRES VARGAS ISAZA ◽

WILFREDO MONTEALEGRE RUBIO

Keyword(s):

Heat Transfer ◽

Processing Time ◽

Simulation Analysis ◽

Injection Molding Process ◽

Molding Process ◽

Polymer Injection ◽

Injection Process ◽

Efficient Performance ◽

Volume Method ◽

Common Situation

A common situation in the design of injection molds is to achieve an efficient performance in terms of heat transfer, this will allow a higher production rate with better finished parts [1]. One of the most important factors in the design is the cooling time: about 80% of the processing time is determined by it [2]. Seeking to contribute with the increase of productivity, this work presents results of simulations through the finite volume method (MVF) of the injection molding process; those results are compared with an analysis of design of experiments (DOE) with different injection conditions, revealing the study variables that are fundamental to improve the process. Thus, a statistical analysis and a computer simulation analysis are presented to identify the variables inherent to the process and recommend their values.

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