ABSTRACT
Regimes of vaporization in capillaries and capillary structures are restricted by liquid flow supply, heat input conditions, and geometry of capillary structure (Figures 3.1-3.4).
Liquid flow arrangement is assigned mainly to the physical nature of the forces maintaining the heat carrier circulation; the following cases could be specified:
Forced liquid supply under the action of external forces, when the force • volumetric density can be estimated by the following dimensionless parameters: rw2/L, r′w02/de, Δp′/L. Gravitational heat carrier supply (natural convection). The heat carrier flow • is governed by the action of Archimedean forces. Their density can be evaluated as Fg = (r′ − r″)g sin b , where b is the angle accounting for the capillary channel orientation in the gravity field. Capillary liquid supply, when the liquid motion is maintained by the action • of capillary forces. Their density can be estimated by as Fs = s /(aL), where L is the length of the capillary channel, a is the characteristic length of the channel, and 1/a is an interface curvature). Inertial (pulsating) heat carrier supply, when a periodic liquid feeding of • the heat transfer surface occurs under the action of inertial forces. These inertial forces appear due to the vaporization process. Density of the forces can be estimated as FIn = (r″w0″2)/L. Combined heat carrier flow, when densities of two or more volumetric • forces cited above have the same order of magnitude, that is, Fg and Fw, or Fg and Fs , etc.
