THERMAL SCIENCE

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Heat transfer enhancement from power transformer immersed in oil by earth air heat exchanger

ABSTRACT
In this study, the modelling of power transformer with (250kVA) by using (ANSYS17.1/FLUENT) code program was done. The power transformer was connected with earth air heat exchanger to decrease the temperature of (oil, core, and coils) of transformer which will increase its efficiency for preventing the damage and/or failure. The case study used the weather conditions of Nasiriya city (Iraq) at 1July with 50oC as maximum ambient temperature and full electrical load of the power transformer. In addition to different pipe diameter, length of earth air heat exchanger and different air velocity entering to pipe. The results showed the temperature of (oil, core, and coils) for power transformer decreased with increase the pipe length and earth air heat exchanger depth underground. The air velocities inlet to earth air heat exchanger that used in the study were (2, 4 , 6 m/s respectively)and the results showed the increasing of air velocity inlet to earth air heat exchanger should decrease the temperature of (oil, core, and coils) for power transformer and increase the thermal conductivity of oil. The study concluded when using earth air heat exchanger in the power transformer and performance of power transformer will be increasing and led to decrease the temperature of oil about (18.5°C).The results showed a significant convergence with previous researches.
KEYWORDS
PAPER SUBMITTED: 2017-12-31
PAPER REVISED: 2018-03-05
PAPER ACCEPTED: 2018-03-24
PUBLISHED ONLINE: 2018-04-28
DOI REFERENCE: https://doi.org/10.2298/TSCI171231116H
REFERENCES
  1. Nazeer, W. A., et al., In-situ Species, Temperature and Velocity Measurements in a Pulverized Coal Flame, Combustion Sciences and Technology, 143 (1999), 2, pp. 63-77
  2. Zhang, X.,Wang, Zh., Liu, Q., Jarman, P.,and Negro, M., Numerical investigation of oil flow and temperature distributions for ON transformer windings, Applied Thermal Engineering,130(2018),pp.1-9.
  3. Garelli, L., Rodriguez, G.R., Storti, M.,Granata, D.,Amadei, M.,Rossetti,M., 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.
  4. Fernández, I.,Delgado, F.,Ortiz, F.,Ortiz, A.,Fernández, C.,Renedo, C.J.,Santisteban, A., Thermal degradation assessment of Kraft paper in power transformers insulated with natural esters, Applied Thermal Engineering,104 (2016),pp. 129-138.
  5. Kondrashova, Yu.N.,Khramshin, R.R.,Nikolaev,A.A.,Shurygina, G.V., Analysis of thermal state of power transformer of captive power plant, International Conference on Industrial Engineering, Procedia Engineering 129 ( 2015 ),pp. 832 - 838.
  6. Kim,M.g.,Cho, S.M.,Kim,J.K., 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. Gastelurrutia, J.,Ramos, J. C.,Larraona, G. S.,Rivas, A.,Izagirre, J., and Río, L., Numerical modelling of natural convection of oil inside distribution transformers, Applied Thermal Engineering, 31 (2011),4,pp. 493-505.
  8. Taghikhani,M.A., and Gholami,A., Prediction of hottest spot temperature in power transformer windings with non-directed and directed oil-forced cooling, Electrical Power and Energy Systems, 31 (2009), 7-8, pp. 356-364.
  9. Hosseini,R., Nourolahi,M., and Gharehpetian,G.B., Determination of OD cooling system parameters based on thermal modeling of power transformer winding, Simulation Modelling Practice and Theory, 16 (2008),6,pp. 585-596.
  10. Milad Akbari, Mehdi Allahbakhshi, Rashid Mahmoodian, Heat Analysis of the Power Transformer Bushings in the Transient and Steady States Considering the Load Variations, Applied Thermal Engineering, 121 ( 2017), pp.999-1010.
  11. Luciano Garelli, Gustavo Ríos Rodriguez, Mario Storti, Daniel Granata, Mauro Amadei, Marcelo Rossetti, 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.
  12. Xiang Zhang, Zhongdong Wang, Qiang Liu, Paul Jarman, and Massimo Negro, Numerical investigation of oil flow and temperature distributions for ON transformer windings, Applied Thermal Engineering, 130 ( 2018), pp.1-9.
  13. Practical specification of JOYSAN TURKISH TRANSFORMER .transformer final report. Power: 250kVA, serial number 14148, Date 14.01.2014.www.joysantransformator.com.
  14. Al-Ajmi,F.,Loveday,D.L.,and Hanby,V.I., The cooling potential of earth-air heat exchangers for domestic buildings in a desert climate, Building and Environment, 41 (2006), 4, pp. 235-244.
  15. Pop,I. I., Ingham,D. B., Convective Heat Transfer: Mathematical and Computational Modelling of Viscous Fluids and Porous Media, Elsevier Science& Technology Books, Pergamon, 2010.
  16. Inaba, H.,Zhang, Y.,Horibe, A., and Haruki,N., Numerical simulation of natural convection of latent heat phase-change-material microcapsulate slurry packed in a horizontal rectangular enclosure heated from below and cooled from above, Heat Mass Transfer, 43 (2007),5,pp.459-470.
  17. El Wakil,N.,Chereches,N.C., and Padet,J., Numerical study of heat transfer and fluid flow in a power transformer, International Journal of Thermal Sciences, 45 (2006),6,pp. 615-626.
  18. Launder,B. E., and Spalding,D. B., The Numerical Computation of Turbulent Flow, Computer Methods in Applied Mechanics and Engineering, 3 (1974),2,pp. 269-289.
  19. Hanby V. Combustion and pollution control in heating systems. London, UK: Springer; 1994.
  20. Gnielinski V. New equation for heat and mass transfer in turbulent pipe and channel flow. International chemical engineering,16(1976),pp. 359-68.
  21. Kusuda T.,Piet,O., and Bean, W., Annual variation of temperature field and heat transfer under heated ground surface, slab-on grade floor heat loss calculation, Building Science Services, Washington DC,U.S.A,1983.
  22. Moreland FL, Higgs F, and Shih J, (editors.), Earth-covered buildings Proceeding of conference in Fort Worth, Texas, U.S., May 1978,Washington, DC: D.O.E., 1980.MD. National Bureau of Standards, 1983.
  23. Labs,K., and Cook, J., Passive cooling. Cambridge Massachusetts, MIT Press, London, England, 1989.
  24. Al-Ajmi F, Hanby VI, Loveday DL., Thermal performance of the sub-soil environment in dry desert climate, ASHRAE Transaction, 108, Pt. 2, 2002.
  25. International Standard, IEC(60137),Fifth edition,2003-08.
  26. Hasan, M. I., Using the transformer oil-based Nano fluid for cooling of power distribution transformer, International Journal of Energy and Environment,8 (2017), 3, pp.229-238.