Numerical Simulation Of Enhanced Heat Transfer On Panel Type Radiator Of Oil-Immersed Transformer

Heat transfer exchange among cool or hot fluids has a wide application in many fields, such as dynamic, chemical engineering, metallurgy, light industrial,building, pharmacy and central heating system. So, heat-exchange facility is indispensable to commercial operation. Heat exchangers with new-style, higher heat transfer efficiency and more compact are developed in the wake of technological progress in heat transfer enhancement and demanding on energy conservation. Panel-type radiator is an effective heat exchanger for cooling large oil-immersed transformer.In this paper three different methods for heat transfer enhancement on panel-type radiator were devised according to traditional theory of heat transfer enhancement and field-synergy principle:①Longitudinal vortex generators fixed in flow channel.②Inserting twisted-tape in channel.③Using semi-circular band and semi- elliptic band to amplify superficial area of panel-type radiator.On the basis of trim size of the oil channel, in the paper different geometric construction parameters of three models were changed, numerical calculations were done using Fluent software, analytical investigation on the results were given in depth, and ultimately the optimum geometry parameters for the three models and the optimum way to heat transfer enhancement were obtained.The results indicated that Nu/Nu0 for the first model was improved 5.5%, the maximum value ofηwas 1.0417, Nu/Nu0 for the second model was improved 6.0%, the maximum value ofηwas 1.01684, and Nu/Nu0 for the third model was improved 3.7%, the maximum value ofηwas 1.05872. By contrast, heat transfer effect of the second model was the best, but flow resistance was biggest, and the last model was the best way to heat transfer enhancement.