19-08-2014, 10:39 AM
Ultrasonic atomisation is studied as a new technique of atomisation using different fluids and slurries. There are two major hypotheses that explain the mechanism of liquid disintegration during ultrasonic atomisation, capillary wave hypothesis and cavitation hypothesis. Extent of cavitation during ultrasonic atomisation has been studied. Degradation of KI was studied as a model reaction to check existence of cavitation phenomenon.
Ultrasonic atomisation is studied as a new technique of atomisation using different fluids and slurries. There are two major hypotheses that explain the mechanism of liquid disintegration during ultrasonic atomisation, capillary wave hypothesis and cavitation hypothesis. Extent of cavitation during ultrasonic atomisation has been studied. Degradation of KI was studied as a model reaction to check existence of cavitation phenomenon.
High-speed photographic technique was used to study the ultrasonic atomisation. Attempts were made to study the Taylor instability during the film break up phenomenon.
Ultrasonic atomisation technique was used to study the slurry atomisation. Aqueous TiO2 slurry was atomized and dependence of droplet size on the various operating parameters and physiochemical properties were studied.
Ultrasonic atomisation was used in spray drying to get tailor made crystal size. The solute material was dissolved in the solvent to a known concentration. The concentration of the solute in the solvent decides the particle size and can be estimated by doing material balance on a single drop produced by ultrasonic atomization. Measuring the crystal size, droplet size was back calculated and dependence of droplet size on various operating parameters were studied.
The concept of the sonocrystallization has applied to study the antisolvent based precipitation of high-energy material (explosives). Dispersion of antisolvent is equivalent to the atomisation of one fluid into another, where one liquid is atomized into another. The method has been developed to control the crystal size and crystal size distribution of the high-energy materials (CL20). The crystal size was drastically reduced to 2 microns with perfect crystal geometry from 35 microns of irregular shapes.
Time of precipitation was reduced to few minutes compared to hours with higher yields compared to conventional precipitation method, which requires few hours. Also the experiments were performed to improve the purity of the crystals by using the ultrasound during the process of precipitation.
The effect of the cavitation phenomenon on size reduction of the rubber latex particles in suspension was studied. The break up of highly elastic semi-fluid such as the rubber latex is also controlled by the forces responsible for atomisation. The acoustic and hydrodynamic cavitation has been studied for the same. Transient as well as stable cavitation was used to get different reduction ratios and final required size. The energy balance calculations were carried out and based on the work index values obtained the hydrodynamic cavitation with stable cavitation mode was proved to be the best method for obtaining the nano size (20 nm with less than 2% variation) rubber particles. The scale of the operation was 50 lit/batch (3 kg solids/ batch), which is quite high comparing with the conventional methods used for obtaining nano particles. Also the processing cost for this method was estimated to be very low.