HYDRODYNAMICS AND HEAT-TRANSFER AT THE BOILING OF LIQUIDS IN THIN-LAYER EVAPORATOR WITH VIBRATING ELEMENT

This paper extends and broadens our present knowledge concerning hydro -dyanmics and heat transfer during boiling of liquids in a thin-layer evaporator equipped with a spiral element. The application of the spir al element in the thin-layer evaporator of static type (STLE) radicall y changes the hydrodynamics and consequently the rate of heat transfer . Measurements were carried out on distilled water and ethylene glycol . 416 measurements of individual heat transfer coefficients (IHTC) wer e performed which included 86 measurements in the STLE, 77 measurement s in the thin-layer evaporator equipped with immovable spiral element (TLE) with (ISE), and 253 measurements in the thin-layer evaporator wi th movable spiral element (TLE) with (MSE). Experimental data were cor related using similarity theory and dimensional analysis. The experime ntal results obtained in the TLE with MSE were compared with adequate data obtained in the TLE with ISE. In the investigated range of freque ncy and amplitude the increase of IHTC amounted to 10.1% for distilled water and for ethylene glycol 30.7%.