Investigation of Mineral Oil-Based Nanofluids Effect on Oil Temperature Reduction and Loading Capacity Increment of Distribution Transformers

Taheri, Ali Asghar; Abdali, Ali; Taghilou, Mohammad; Alhelou, Hassan Haes; Mazlumi, Kazem

doi:10.1016/j.egyr.2021.07.018

Cited by 22 publications

(4 citation statements)

References 27 publications

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“…When working in natural convection, m is 0.8 [32], n is 0.8 [32], Δθ topr , Δθ hsr , and R can be obtained from the data of the transformer factory temperature rise test report (shown in Table 2). Additionally, if K and θ a are known, θ top and θ hs can be calculated by Equation (14). However, it is worth noting that when the cooling fan is added at the bottom of the radiator, the The convective heat transfer coefficient/(W/(m 2…”

Section: Verification Of Improved Hot-spot Temperature Evaluation Met...mentioning

confidence: 99%

“…In [11,12], some methods were proposed to improve the average heat transfer coefficient on the air side of the radiator by adjusting the structural design of the radiator. Subsequently, some material performance optimization measures, such as doping graphene [13] and adding nanoparticles [14], were applied to improve the thermal conductivity of radiators. But the above investigations mainly aimed at the improvements of transformer design, which means that a new transformer needs to be replaced.…”

Section: Introductionmentioning

confidence: 99%

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Thermal evaluation optimization analysis for non‐rated load oil‐natural air‐natural transformer with auxiliary cooling equipment

Zhang

Liu

Lin

et al. 2022

IET Generation Trans & Dist

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Obtaining an accurate hot-spot temperature of oil-natural air-natural (ONAN) transformer is important for evaluating its operation status and load capacity. To meet the overload requirement, the cooling fan is usually added to the operating ONAN transformer as the auxiliary cooling equipment. However, the hot-spot temperature evaluation methods in this case lacked discussion currently. To address this issue, an improved hot-spot temperature evaluation method for the ONAN transformer considering the thermal resistance on the air side of radiator was proposed in this paper. Subsequently, the calculation method for the key parameter of the improved method (the convective heat transfer coefficient on the air side of radiator) was conducted. The accuracy and superiority of the improved method compared with the IEEE loading guides were verified by the manufacturer's software. Finally, the maximum steady-state load of the ONAN transformer with cooling fan was achieved by the improved method. The results indicate that for the case of non-rated load, the improved method can provide a more accurate thermal evaluation of ONAN transformer under different cooling modes than the IEEE loading guides. The method proposed in this paper can provide a reference for selecting the cooling fan parameters and formulating the load control strategy of the ONAN transformer.

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Section: Verification Of Improved Hot-spot Temperature Evaluation Met...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Thermal evaluation optimization analysis for non‐rated load oil‐natural air‐natural transformer with auxiliary cooling equipment

Zhang

Liu

Lin

et al. 2022

IET Generation Trans & Dist

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“…Transformers, which account for almost 60% [1] of the network cost, provide the connection between production and consumption due to changes in voltage level [2]. Transformer oil acts as a very important insulating part of the transformer.…”

Section: Introductionmentioning

confidence: 99%

Experimental Analysis and Physical Mechanism Investigation of Al2O3 Effect on New and Aged Transformer Oil Properties

Mashhadzadeh

Seyyedbarzegar

Samani

2023

IJE

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Al2O3 nanoparticles were used to improve the performance of the vital properties of transformer oil (TO) under normal operating conditions and when subjected to thermal aging. Different weight percentages of Al2O3 in the TO were considered to maximize the breakdown voltage (BDV). Al2O3 nanofluid (NF) increases the BDV by 116% (31.1 kV to 67.4 kV) and the heat transfer by 33.4%, and also minimizes partial discharge (PD) by 66%. The reduction of PD is also related to the ability of Al2O3 to adsorb hydrogen and acetylene, two oil-soluble gases that are effective in PD. Even Al2O3NF was more resistant to water content in TO. BDV for TO and Al2O3NF, when water content increased to more than 30 ppm, were reduced by 57% and 19%, respectively. According to Arrhenius equation, both samples were placed at 120°C for 29 days to age samples (equivalent to about 30 years). Aged Al2O3NF has continued its exceptional performance and improved BDV by 121% compared to aged TO, and also Al2O3NF showed its capacity well and improved PD compared to aged TO by 71%. All the favorable properties of Al2O3NF are conditional on the stability of Al2O3. FESEM confirms the stability of Al2O3.

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“…The numerical simulations revealed that the application of CuO nanoparticles in pure oil leads to lower hotspot temperature and a decrease in the average and maximum temperature of the fluid. Another simulation study considered two volumetric concentrations of multi-walled carbon nanotubes and three volumetric concentrations of diamond nanoparticles dispersed in mineral oil [42]. The numerical results were compared with the experimental study performed with a 500 kVA distribution transformer.…”

Section: Introductionmentioning

confidence: 99%

Effect of ferrofluid magnetization on transformer temperature rise

Rajňák¹,

Franko²,

Paulovičová³

et al. 2022

J. Phys. D: Appl. Phys.

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In electrical engineering, the heat transfer can be enhanced by changing the thermophysical properties of insulating oils. In this paper, a single-phase power transformer with a nominal power of 5 kVA is subjected to a temperature rise test with three different transformer liquids. The first test is carried out with a novel gas-to-liquid transformer oil applied as a cooling and insulating medium. The other tests are conducted with ferrofluids based on this oil and MnZn ferrite nanoparticles of a low and a high nanoparticle concentration. The ferrofluids are characterized by magnetization curves, magnetic susceptibility and temperature-dependent magnetization measurements. The nanoparticle size distribution is determined from dynamic light scattering and the magnetization data. From the temperature rise profiles of the transformer at various inner locations, it has been found that the low-concentrated ferrofluid significantly reduces the transformer temperature rise. The enhanced cooling performance is ascribed to the thermomagnetic and natural convection, and increased thermal conductivity. The application of the ferrofluid with the high nanoparticle concentration resulted in a remarkable increase of the transformer temperature rise. The deteriorative cooling effect is attributed to the hindered natural and thermomagnetic convection due to the high ferrofluid magnetization and strong magnetic interaction of the ferrofluid with the magnetic field near the transformer core.

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Investigation of Mineral Oil-Based Nanofluids Effect on Oil Temperature Reduction and Loading Capacity Increment of Distribution Transformers

Cited by 22 publications

References 27 publications

Thermal evaluation optimization analysis for non‐rated load oil‐natural air‐natural transformer with auxiliary cooling equipment

Thermal evaluation optimization analysis for non‐rated load oil‐natural air‐natural transformer with auxiliary cooling equipment

Experimental Analysis and Physical Mechanism Investigation of Al2O3 Effect on New and Aged Transformer Oil Properties

Effect of ferrofluid magnetization on transformer temperature rise

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