Study On The Temperature Field In A Stirred Tank Equipped With Jacket

Liquid crystal thermography, a novel technique for temperature measurement, was developed and applied to study the temperature distribution in a stirred tank which was equipped with jacket. Microencapsulated thermochromic liquid crystals(TLCs), which respond to changes in temperature by changing color, were taken as temperature indicator. Temperature was measured after the TLCs were mixed with the fluid in stirred tank evenly. A suit of equipment, including stirring system, heat transfer system, illumination system and picture acquiring/processing system, was established. By several of trials, perfect operation condition was affirmed, and the technique was applied successfully to the experimental study on a stirred tank of bigger size in lab.The stirred tank which was 500mm in diameter, 600mm in height and with a flat bottom, was surrounded by a regular octagonal cooling water jacket outside. Both the tank and the jacket were made of plexiglass. A heating rod was emplaced in the center area of tank. Two types of impeller, CBY propeller and Rushton turbine, were used. The fluid in the stirred tank were Newtonian fluid, glycerin, and pseudo-plastic fluid, aqueous solution of polyacrylamid(PAM) respectively. The glycerin's temperature distribution and PAM's temperature boundary layer were measured by using liquid crystal technique. What's more, the development of flow field in the tank could be observed at the same time as the temperature field.Another method for the study of heat transfer in a stirred tank, besides experimental, is numerical simulation. Here, CFD(Computational Fluid Dynamics) software CFX-4 was used to carry out primary study on numerical simulation of temperature field in a stirred tank. The simulation results were checked with the experimental data.