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.