الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 174 |  |  |
| | | from | 174 | | |
Abstract
Rates of mass transfer at a serpentine tube baffle in a cylindrical stirred tank reactor were measured by the diffusion controlled dissolution of copper in acidified dichromate. The serpentine tube baffle has the potential to act as a catalyst support and a cooler. As such stirred tank reactors with serpentine tube baffles are suitable for conducting exothermic diffusion controlled liquid-solid catalytic reactions which need rapid temperature control e.g immobilized enzyme catalyzed biochemical reactions. Variables studied were: 1. Impeller rotation speed. 2. Impeller geometry (45 pitched blade turbine and 90 four blade turbine). 3. Physical properties of the solution. 4. Pitch (copper tube separation within the serpentine tube). 5. Diameter of the serpentine tube baffle. The study revealed the following results: The mass transfer coefficient increases with increasing impeller rotation speed rasied to an exponent ranging from 0.57 to 0.71 depending on impeller and baffle geometry. The 90o turbine produces higher rates of mass transfer compared to the 45o pitched blade turbine. Serpentine tube baffle with separated tubes produces higher rates of mass transfer than a baffle with closely spaced tube. Mass transfer data for axial and radial flow impeller were correlated by dimensionless mass transfer equations which can be used in scaling up the present reactor as well as calculating the rate of heat transfer (by analogy) across the serpentine tube baffle cooler. The advantages of the present reactor compared to other heterogeneous stirred tank reactor such as the slurry reactor were pointed out.