EFFECTS OF ENZYME MICROCAPSULE SHAPE ON THE PERFORMANCE OF A NONISOTHERMAL PACKED-BED TUBULAR REACTOR

The effects of enzyme microcapsule shape (spherical, cylindrical and f lat plate) on the performance of a nonisothermal, packed-bed reactor h ave been modeled as a function of Blot number and Peclet number for ma ss and heat transfer (Bi-m, Bi-h, Pe(m) and Pe(h)), and dimensionless heat of reaction alpha. Under the given simulation conditions, only hi gher values of Bi-m and Bi-h (> 2.5) confirm the influence of microcap sule shape on the reactor performance such that the axial and overall conversion and bulk temperature decrease as follows: spherical > cylin drical > flat plate. In terms of the shape-independent modified Blot n umber, Bi = Bi/{(n + 1)/3}, this order is retained for 2 < Bi* < 8. T he influence of increasing Pe(m), Pe(h), and alpha on conversion and b ulk temperature also follows the above order. For the flat plate, the exit conversion and temperature are not influenced by Pe(m) and Pe(h), that is, mass transfer and thermal back-mixing effects, respectively. On the other hand, for the spherical and cylindrical microcapsules, o verall backmixing effects are negligible only beyond a critical value of Pe(m) (similar to 7) and Pe(h) (similar to 1.75). The conversion an d bulk temperature increase with the increase in alpha, independent of the microcapsule shape. The spherical and cylindrical microcapsules, unlike the flat plate, cannot be considered isothermal.