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

Abstract

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 spiral element in the thin-layer evaporator of static type (STLE) radically 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) were performed which included 86 measurements in the STLE, 77 measurements in the thin-layer evaporator equipped with immovable spiral element (TLE) with (ISE), and 253 measurements in the thin-layer evaporator with movable spiral element (TLE) with (MSE). Experimental data were correlated using similarity theory and dimensional analysis. The experimental results obtained in the TLE with MSE were compared with adequate data obtained in the TLE with ISE. In the investigated range of frequency and amplitude the increase of IHTC amounted to 10·1% for distilled water and for ethylene glycol 30·7%.

KEYWORDS:

• Thin-layer evaporator
• Individual heat transfer coefficient
• Vibrating element
• Coefficient of thermal efficiency

Additional information

Notes on contributors

ADAM SKOCZYLAS†

To whom correspondence should be addressed.