Experimental comparison of heat exchange in tanks equipped with helical coil using radial and axial mechanical impellers

Marcilio Dias Lopes, Carlos Alberto Amaral Moino, Aldo Ramos Santos, Karina Tamião de Campos Roseno, Vitor da Silva Rosa, Deovaldo Moraes Junior

Abstract


Tanks with mechanical impellers are used in all chemical and petrochemical industry segments, being the most common applications: reactors, substance homogenizing, solids solubilization and products dissolution. It is common that these processes require a heat transfer operation and, in such cases, may be used spiral or helical coils, jackets and tubular baffle. For each operation involving agitation and heat transfer, there is an overall heat transfer coefficient that depends on the physical properties of the fluid, the vessel geometry, the heat source, the impeller type and rotation. This study aimed to determine experimentally the Sieder-Tate equation constants to calculate the outer film heat transfer coefficient of a helical coil as a function of which impeller used and compare the thermal efficiency with two impellers used. The experimental unit basically consisted of a 50-L tank, axial and radial impellers and helical coil. Water was used as the heater fluid. The water flow rate was 1,8 L/min and the inlet temperature was 62°C. The cold fluid flow was 1,0 L/min and inlet temperature between the range of 29-45°C. The rotation varied between the range of 90-330 rpm. The results allow to affirm that the greatest heat transfer was obtained using the radial impeller.

Key word

Mechanical impeller, helical coil, Sieder Tate equation.


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