Effect of the layer height on heat transfer and the critical heat flux in evaporation of a fluid under low pressure

The results of an experimental study of heat transfer in the evaporation of a thin horizontal layer of VM-1S vacuum oil at low pressure are presented. The experimental data for the dependence of the heat flux density on the temperature difference at the critical heat flux in a wide range of heights of the liquid layer are assessed. It is shown that the critical heat flux increases in a narrow range of the layer heights by more than an order of magnitude. The values of the critical heat flux density in layers with a height less than the capillary constant are described by the Kutateladze equation. With increasing thickness of the layer, the critical heat flux increases sharply and reaches a constant value, which is in good agreement with the dependences calculated by Yagov and Landau.