Effect of Microwave Heating on the Residence Time Distribution in a Tubular Reactor

Microwave (MW) heating has been revolutionary in various applications, including chemical synthesis. A nonconventional heating approach reduces the reaction time significantly. For a continuous flow tubular reactor under microwaves, the temperature would change from the inlet to the outlet depending on the dielectric constant of the reaction mass, which would further change the physical properties, viz., the density and viscosity of the material. Such changes in the physical properties would lead to nonideal flows and would affect the conversion as well as selectivity for reactions. In order to understand the extent of such a nonideality, here for the first time we have done systematic studies of the residence time distribution in a helical coil reactor. The axial dispersion model has been modified to take into account the temperature-dependent physical properties of the fluid. The empirical correlation for the dispersion number is obtained over the range of 450 ≤ P (W) ≤ 1200 and 60 ≤ T (°C) ≤ 150. This study will help model the reaction kinetics as well as reactor design under microwave specifically for heat sensitive reactions where variations in the overall residence time would affect the yield and selectivity of the end product.