Evaluation of steady flow profiles in rectangular and circular packed beds by a variational method
✍ Scribed by D. Vortmeyer; J. Schuster
- Book ID
- 103008074
- Publisher
- Elsevier Science
- Year
- 1983
- Tongue
- English
- Weight
- 877 KB
- Volume
- 38
- Category
- Article
- ISSN
- 0009-2509
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✦ Synopsis
AbstracCThe Brinkman-equation is solved by an equivalent variational problem in order to obtain steady flow profiles which satisfy the conditions w = 0 and l = I at the container wall of a packed bed. The quite large deviations between calculated and measured profiles are fulIy explained. An analytical expression is developed with sufficient accuracy. The main body of calculations is performed for isothermal flow, however flows under non-isothermal conditions also are considered. 1. INTRODUCTION Recently published research work emphasizes the importance of porosity changes-Buchlin et of. [ II-and in particular of the corresponding velocity changes near the container wall-Lerou and Froment [Z], Kalthoff and Vortmeyer [3], Vortmeyer and Winter [4l_for the analysis of packed bed chemical reactors. In fact the results of [3,4] show clearly by comparison with experiments that improvements in the theoretical prediction of reactor performance are obtained by assuming a non-uniform flow distribution within the packed bed. While the changes in porosity near the wall&111 are well known, there is no general consensus on the precise flow profiles inside the packed bed. Flow measurements inside the bed are very difficult to perform as reported by Cairns and Prausnitz[l2]. Since this type of measurements is rather uninformative for various reasons, the main body of flow profiles was obtained by measurements a few millimeters above the exit cross-section of the packed bed. This kind of work was performed, e.g. by Schertz and Bischoff[l3], Dornweiler and Fahien[l4], Morales et al.[15], Schwartz and Smith[l6], Calderbank