Page 242 - Packed bed columns for absorption, desorption, rectification and direct heat transfer
P. 242

232


                                  Another equation, describing the experimental results of different
                           authors for Raschig rings 25.4 mm and 12.7 mm, is proposed also by Maeias-
                           Salinas and Fair [205].


                           Pe G =998.19Re- 0Mll .10~ 0Mm "^                                 (128)




                           3.2,1,2.1.5.2. Axial mixing in the liquid phase
                                  The axial mixing in the liquid phase of random packings is investigated
                           by many scientists [115-126,203-213].
                                  For determination of the axial mixing coefficient in the liquid phase
                           Otake et al. [115] proposed the equation:



                                                        s
                                                   1
                           Pe L = 5 ^ = 0.527 Rej^  Ga^ ,                                   (129)
                                   ML
                                                                                       2
                           where D L is the axial mixing coefficient for the liquid phase in m /s. Re u is
                           the Reynolds number defined with the diameter of a packing element and with
                           the average real liquid velocity in the packing as follows:



                           R      ^



                                  The Galilei number is also defined with the packing element size:







                                  Later Kunugita Otake and Yamanashi [117] presented the equation


                                                0 77
                                           33
                           Pe L = 1.425GoC"  Re ^                                           (130)
                                  Based on their own data for Berl saddles and Raschig rings with 7.85 to
                           15.5 mm size, Sater and Levenspiel [118] offered the equations:
   237   238   239   240   241   242   243   244   245   246   247