Research On Convective Heat Transfer Characteristics Of Kerosene At Subcritical Pressure

In the vertical tube,the development of the kerosene’s two phase flow is relatively simple at subcritical pressure.Nucleate boiling begins on the surface of the tube,and bubble flow occurs in the circular tube.When annular appears in the tube,gas separates the liquid from the heating pipe.The kerosene liquid evaporates on the gas-liquid interface.Boiling heat transfer turns into single phase convection heat transfer in the tube.In horizontal tube,gas gathers in the upper channel and liquid gathers in the down channel.In horizontal square channel,the transition of kerosene from liquid flow to gas flow was investigated.Nucleate boiling occurs on the heating plate,bubble flow appears in square channel.Then bubble flow turns into block flow.When block flow turns into wave flow,the heating plate is still covered by kerosene liquid.And the liquid layer is so thick that nucleate boiling is still sustained on the surface of the heating plate.With the liquid evaporating,the liquid layer becomes thinner and thinner.And nucleate boiling disappears on the surface of the heating plate,the heat transfer type changes.The energy is transferred by heat conduction and convection between heating plate and liquid layer.On the gas-liquid interface,vaporization of kerosene takes place continuously.The liquid layer is finally dried out,energy transfer turns into single phase heat convection between heating plate and kerosene gas.In square channel,the heat transfer type changes with the development of two-phase flow of kerosene.And the heat transfer type includes single phase convection heat transfer,nucleate boiling and film boiling.