International Scientific Journal

Thermal Science - Online First

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Analysis of external heat dissipation enhancement of oil-immersed transformer based on falling film measure

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.
PAPER REVISED: 2021-11-25
PAPER ACCEPTED: 2021-12-03
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