Measurement And Numerical Simulation Of The Temperature Distributions In An Agitated Tank Heated By Vertical Tubes

Liquid crystal technique was used to measure the glycerin temperature distributions in an agitated tank heated by vertical tubes. The stirred tank which was 500mm in diameter, 600mm in height and with a flat bottom, was surrounded by a regular octagonal jacket outside. Both the tank and the jacket was made of plexiglass. Four sets of vertical tubes were fixed symmetrically on the wall of the tank. Each set of the tubes was made up of two series U heating rods which power was 150W.The axial and horizontal section temperature distributions of the glycerin in the tank which was equipped with impellers of CBY, PBT and CBY-D were studied.The effects of time, rotation speeds and the distance of impeller from the bottom on the temperature distributions were discussed. And the temperature distributions in the tank of different type of impeller with the same power input were compared.The soft of CFX-4 was used to simulate the glycerin temperature distributions in the agitated tank equipped with PBT impeller. And the axial and horizontal section temperature distributions of simulation were compared with the results of the experiments. They were almost identical except some difference near the heating tubes. The results of the simulation were used to compute the local heat transfer film coefficients on the out surface of vertical tubes at different height. And the computational results were compared with the results of Wu Haosong who measuered the local heat transfer film coefficients by using calorimetric method. The two distribution trends of local heat transfer film were consistent.