Heat Transfer Enhancement in Transformers by Optimizing Fin Designs and Using Nanofluids

  • Muhammad FarhanEmail author
  • Muhammad Saad Hameed
  • Hafiz Muhammad Suleman
  • Muhammad Anwar
Research Article - Mechanical Engineering


In this paper, we have simulated different fin geometries at different flow intensities to study the optimum design for better flow and heat transfer characteristics to be used in transformers’ cooling. We use energy density of oil (pressure) as flow intensity parameter being a compressible fluid which is dependent on temperature variation. We observe direct proportionality of shear stresses (pressure drop) with flow intensity. Pressure drop is dominant in rectangular fins with higher height-to-width ratio (h/w), and it decreases sharply for lower h / w ratio especially at bends, whereas it is significantly better in conic-shaped fins especially at \(a\ge \) 1.2. We observe an inverse proportionality of temperature drop with the flow intensity due to transient heat transfer phenomenon. We observe smooth temperature drop for conic-shaped fins. We have also investigated oil-based alumina nanofluids (in different wt/V ratios) as coolant for heat transfer enhancement in transformers. It is observed experimentally that dielectric strength improves with oil-based nanofluids. We obtain about 8.67% better results by adding 0.08% particles in oil. Comparative analysis with previous works shows that alumina-based nanofluids have better results than others. Still, there is a lot of work to be done in their use at commercial level due to their short durability.


Transformer Heat transfer optimization Fin design CFD simulation Nanofluids 



Height-to-width ratio


Weight per volume


Computational fluid dynamics


Pak Electron Limited


Semi-implicit method for pressure-linked equations


Scanning electron microscopy

List of Symbols

\(\rho \)

Density (kg/\(\text {m}^{3})\)

\({\varvec{\nabla }}\)

Divergence (1/m)

\(\nabla T\)

Gradient of temperature (\(^{\circ }\)C/m)

\(A_n \)

Cross-sectional area in n-direction (\(\text {m}^{2})\)

\(A_\mathrm{r} \)

Cross-sectional area along radius (\(\text {m}^{2})\)

\(A_\mathrm{s} \)

Surface area (\(\text {m}^{2})\)

\(a, b, r, \dot{h}, k\)

Conic section components


Convective heat transfer coefficient (W/\(\text {m}^{2}\)\(^{\circ }\)C)


Thermal conductivity (W/m \(^{\circ }\)C)

\(Q_n \)

Heat transfer rate in n-direction (W)

\(Q_\mathrm{r} \)

Heat transfer rate along radius (W)

\(S_\mathrm{T} \)

Source term


Temperature (\(^{\circ }\)C or K)

\(\mu _\mathrm{f} \)

Dynamics viscosity (Pa s)

\(c_\mathrm{Pf} \)

Fluid specific heat (J/ \(^{\circ }\)C or J/K)


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The authors gratefully acknowledge the Kazmi Electric Works for the experimental support, and Mr. Engr. Momin Khan and Dr. Mahabat Khan for providing useful information, advice and help on various technical issues. This study is sponsored by Institute of Space Technology, Islamabad, Pakistan.


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Copyright information

© King Fahd University of Petroleum & Minerals 2019

Authors and Affiliations

  1. 1.Department of Mechanical EngineeringInstitute of Space TechnologyIslamabadPakistan
  2. 2.State Key Laboratory of Multiphase Flows in Power EngineeringXi’an Jiaotong UniversityXi’anPeople’s Republic of China
  3. 3.Department of Mechanical EngineeringUniversity of Engineering and TechnologyLahorePakistan
  4. 4.Faculty of ScienceUniversity of NottinghamNottinghamUK

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