THERMAL SCIENCE

International Scientific Journal

ANALYSIS OF EXTERNAL HEAT DISSIPATION ENHANCEMENT OF OIL-IMMERSED TRANSFORMER BASED ON FALLING FILM MEASURE

ABSTRACT
With the increase of power load, the overheating problem of oil-immersed transformer in operation cannot be ignored. Therefore, it is necessary to propose reasonable heat dissipation enhancement measure for oil-immersed transformer in operation and study the influence of the measure on the internal temperature of transformer. The heat transfer process of oil-immersed transformer is analyzed, and the air-side heat transfer coefficient is pointed out to be the important parameter limiting the heat dissipation capacity of the transformer. In order to improve heat dissipation capacity, the measures based on cooling fans and falling film are proposed and the calculation methods for the air-side heat transfer coefficient are conducted, respectively. Moreover, the top-oil temperature and hot-spot temperature under two measures are compared by the thermal-fluid coupling model of oil-immersed transformer. For the transformer operating at rated load and the ambient temperature of 25°C, after the cooling fans are adopted, the top-oil temperature and hot-spot temperature can be reduced by 22.4°C and 20.7°C, while after the falling film is adopted, the top-oil temperature and hot-spot temperature can be reduced by 31.2°C and 28.7°C, respectively. The results show that the falling film is a more effective heat dissipation enhancement measure, which can meet the higher load demand of oil-immersed transformer.
KEYWORDS
PAPER SUBMITTED: 2021-04-09
PAPER REVISED: 2021-11-25
PAPER ACCEPTED: 2021-12-03
PUBLISHED ONLINE: 2022-04-09
DOI REFERENCE: https://doi.org/10.2298/TSCI211015041L
CITATION EXPORT: view in browser or download as text file
THERMAL SCIENCE YEAR 2022, VOLUME 26, ISSUE Issue 6, PAGES [4519 - 4533]
REFERENCES
  1. Yigit, C., et al., Numerical Investigation of Vapor Phase Drying Process for Drying of Transformer's Insulation Paper, Thermal Science, 24. (2020), 3, pp. 2125-2135
  2. Xu, D.P., et al., Analysis of Winding Temperature Field Under Dynamic Variable Load of Oil-immersed Transformer, Thermal Science, 25. (2021), 4, pp. 3009-3019
  3. Shiravand, V., et al., Improving the Transformer Thermal Modeling by Considering Additional Thermal Points, International Journal of Electrical Power & Energy Systems, 128. (2021)
  4. Pierce, L.W., Predicting Liquid Filled Transformer Loading Capability, IEEE Transactions on Industry Applications, 30. (1994), 1, pp. 170-8
  5. Susa, D., et al., Temperature Rises in an OFAF Transformer at OFAN Cooling Mode in Service, IEEE Transactions on Power Delivery, 20. (2005), 4, pp. 2517-2525
  6. Kim, M.G., et al., Prediction and Evaluation of the Cooling Performance of Radiators Used in Oil-filled Power Transformer Applications with Non-direct and Direct-oil-forced Flow, Experimental Thermal and Fluid Science, 44. (2013), pp. 392-397
  7. Mufuta, J.M., et al., Modelling of the Mixed Convection in the Windings of a Disc-type Power Transformer, Applied Thermal Engineering, 20. (2000), 5, pp. 417-437
  8. Taghikhani, M.A., et al., Prediction of Hottest Spot Temperature in Power Transformer Windings with Non-directed and Directed Oil-forced Cooling, International Journal of Electrical Power & Energy Systems, 31. (2009), 7-8, pp. 356-364
  9. Wu, W., et al., Computational Fluid Dynamics Calibration for Network Modelling of Transformer Cooling Oil Flows-Part I Heat Transfer in Oil Ducts, IET Electric Power Applications, 6. (2012), 1, pp. 19-27
  10. Liang, Y.M., et al., The Optimization of Group Panel-Type Radiator of Transformer, Applied Mechanics and Materials, 733. (2015), pp. 615-18
  11. Garelli, L., et al., Heat Transfer Enhancement in Panel Type Radiators Using Delta-wing Vortex Generators, International Journal of Thermal Science, 137. (2019), pp. 64-74
  12. Yin, Z.D., et al., Improving Thermal Conductivity of Radiators Using a Graphene-doped Coating, Surface Engineering, 37. (2020), 6, pp. 818-821
  13. Rodriguez, G.R., et al., Numerical and Experimental Thermo-fluid Dynamic Analysis of a Power Transformer Working in ONAN Mode, Applied Thermal Engineering, 112. (2017), pp. 1271-1280
  14. Paramane, S.B., et al., A Coupled Internal-external Flow and Conjugate Heat Transfer Simulations and Experiments on Radiators of a Transformer, Applied Thermal Engineering, 103. (2016), pp. 961-970
  15. Paramane, S.B., et al., CFD Study on Thermal Performance of Radiators in a Power Transformer: Effect of Blowing Direction and Offset of Fans, IEEE Transactions on Power Delivery, 29. (2014), 6, pp. 2596-2604
  16. Kim, Y.J., et al., A Numerical Study of the Effect of a Hybrid Cooling System on the Cooling Performance of a Large Power Transformer, Applied Thermal Engineering, 136. (2018), pp. 275-286
  17. Darabi, J., et al., Falling Film and Spray Evaporation Enhancement Using an Applied Electric Field, Journal of Heat Transfer-transactions of the ASME, 122. (2000), 4, pp. 741-748
  18. Sippola, M., et al., Accurate Prediction of High-frequency Power-transformer Losses and Temperature Rise, IEEE Transactions on Power Electronics, 17. (2002), 5, pp. 835-847
  19. Shiravand, V., et al., Prediction of Transformer Fault in Cooling System Using Combining Advanced Thermal Model and Thermography, IET Generation Transmission & Distribution, 15. (2021), 13, pp. 1972-1983
  20. Ko, T.H., et al., Optimal Reynolds Number for the Fully Developed Laminar Forced Convection in a Helical Coiled Tube, Energy, 31. (2006), 12, pp. 2142-2152
  21. Garelli, L., et al., Reduced Model for the Thermo-fluid Dynamic Analysis of a Power Transformer Radiator Working in ONAF Mode, Applied Thermal Engineering, 124. (2017), pp. 855-864
  22. Kim, D.S., et al., Flow Patterns and Heat and Mass Transfer Coefficients of Low Reynolds Number Falling Film Flows on Vertical Plates: Effects of a Wire Screen and an Additive, International Journal of Refrigeration-Revue Internationale Du Friod, 32. (2009), 1, pp. 138-149
  23. Wei, J.Q., et al., Measurement of Liquid Film Coverage on Vertical Plates with Hydrophilic and Structured Surface Treatments, Industrial & Engineering Chemistry Research, 60. (2021), 9, pp. 3736-3744
  24. El Wakil, N., et al., Numerical Study of Heat Transfer and Fluid Flow in a Power Transformer, International Journal of Thermal Science, 45. (2006), 6, pp. 615-626
  25. Skillen, A., et al., Numerical Prediction of Local Hot-spot Phenomena in Transformer Windings, Applied Thermal Engineering, 36. (2012), pp. 96-105
  26. Ruan, J.J., et al., HST Calculation of a 10kV Oil-immersed Transformer with 3D Coupled-field Method, IET Electric Power Applications, 14. (2012), 5, pp. 921-928

© 2024 Society of Thermal Engineers of Serbia. Published by the Vinča Institute of Nuclear Sciences, National Institute of the Republic of Serbia, Belgrade, Serbia. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International licence