| For ensuring rapid development of society and industry, power system adjustenergy structure actively, replacing with large capacity and high parameters of powergeneration and transformation. Therefore, the load of transformers will have been in-creasing. If transformers were overheated for a long time, not only transmission lossesof power system would rise beyond rated conditions, but transformers would lose ef-ficacy in severe cases and then lead to more serious power accident.The research was based on the panel-type radiator of oil-immersed transformers,numerical simulating,by FULENT CFD software, PC2500-26/520panel-type radia-tors on SZ11-240000/220kV transformers. Following the principle of single variable,with remaining outer air heat transfer conditions and inter oil inlet velocity unchanged,the research worked out different cooling results of models which finally comparedwith the initial model. These models were set up by different structure of panel-typeradiators and divided into many control groups, including piece number control group,unequal division oil-duct control group, upper oil pipe dip angle control group andpanel shoulder dip angle control group. After numerical simulating, total heat release,effective heat dissipation area, outlet oil temperature, total coefficient of heat transferand other related coefficient can be compared and analyzed comprehensively. Withthe increase of panel numbers, total heat release of panel-type radiators increased ei-ther, but the efficiency of increase diminished, also the total coefficient of heat trans-fer. All the unequal division oil-duct control group models could increase the totalheat release significantly, no matter B——S——B types or S——B——S types. Notonly could reduce outlet oil temperature, but these models could reduce total area ofheat dissipation and save in material as well. Of all unequal division oil-duct control group models, the B——S——B type II model owned more improved heat transfercapacity. When the dip angle of upper oil pipe increased from0°to5°, each effec-tive heat dissipation parameters were enhanced greatly. But after5°, the parame-ters appeared down trend. Therefore, the shoulder dip angle between5°and10°,heat dissipation capability could have a certain degree of enhancement, although theresults turned out to be a little lower than the other control group models.After comparison and analysis of above control groups, optimize structures ofpanel-type radiators were chosen to numerical calculate integratively. Under the panelnumber25,26,27, selecting B——S——B type II of unequal division oil-duct struc-ture, and combining dip angle of upper oil pipe4°、5°、6°with shoulder dip anglefrom6°to9°,36integrated optimization of structure control groups were made tonumerical calculate deeply. The final calculation results showed that: when choosing25piece of panel and B——S——B type II of unequal division oil-duct structure,with dip angle of upper oil pipe increasing to4°and shoulder dip angle increasing to7°, total heat release of panel-type radiators achieved the maximum of16740.42W.The integrated optimization of structure could maintain original cooling capacity un-der the condition of reducing one piece of panel, and the total coefficient of heattransfer also improved from15.6049W/m2·K to18.1830W/m2·K, increasing theoriginal16.52%. when choosing26piece of panel and B——S——B type II of un-equal division oil-duct structure, with dip angle of upper oil pipe increasing to4°andshoulder dip angle increasing to9°, total heat release of panel-type radiatorsachieved the maximum of17989.928W, increasing1249.553W,about7.46%, com-pared with original structure. Besides, the total coefficient of heat transfer also im-proved to17.4651W/m2·K, increasing the original11.92%. When choosing27pieceof panel, the heat dissipation potential was lower than the results of26pieces of pa-nels, proving that heat transfer enhancement was limited. |
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