An innovative method for cooling oil-immersed transformers by Rayleigh-Bénard convection

Review of the prior technologies for natural cooling oil-immersed electric transformers. Introduction of Rayleigh-Bénard convection and the principle of subcooled liquid boiling heat transfer. An innovative cooling method by Rayleigh-Bénard convection and the transformer structure with tank-top radiators are presented. Detail calculations are made on the heat transfer and heat dissipation of the radiator. A 3400 kVA prototype and its temperature rise are tested.