AN INVESTICATION OF THE OF ACOUSTIC VIBERATIONS TO IMPROVE HEAT TRANSFER RATES AND REDUCE SCALING IN DISTILLATION UNITS USED FOR SALINE WATER CONVERSION

摘要

The present research program has demonstrated the technical feasibility of using acoustic energy to improve the economy of evaporator operation in saline water conversion. It has been shown that improvement in water side heat transfer coefficients can be obtained by the use of acoustic vibrations in the viscous and turbulent flow. Improvement varied from 450% at a Reynolds number of 54-0 to 16% at a Reynolds number of 16,000. It is felt that greater improvement can be obtained at higher flow Reynolds numbers with the use of larger vibration equipment. The experimental unit utilized the transverse vibration of a pipe with water flowing on the outside of the pipe in an annular space. . The data were correlated using both vibration and flow Reynolds number parameters.nThe effect of acoustic vibration on steam condensate film heat transfer coefficient was also studied. An improvement of 57% in the heat transfer coefficient was obtained at a frequency of 75 cps and an ampli¬tude 'of 0.2 inch. This represents a possible 30% increase in evaporator capacity. The data were correlated and an equation developed which related heat transfer improvement with amplitude and frequency.nThe program also evaluated the effect of vibration on the formation of scale on a heat transfer surface under boiling and nonboiling conditions. Both calcium sulfate and sea water were used as scaling liquors. Vibrations definitely caused the scale to flake from the pipe surface. Heat transfer coefficients under boiling conditions were improved with vibration. Better removal of scale under nonboiling conditions was obtained.