(1) The Sherwood numbers at either tube wall probes or inner probes seem to be independent on the tube to particle ratio N. Meanwhile, the mass transfer is stronger at inner probes than that at tube wall probes. Two correlations of mass transfer j factor with Reynolds number are developed for data at wall probes and inner probes. Besides, it is found that mass transfer is enhanced with ordered pore structures in simple cubic packed beds when compared with that in random packed beds.
(2) Three different flow regimes in the packed beds, including laminar flow, transition flow and turbulent flow are identified according to the analysis of Fluctuating Rate (FR) of limiting current signals. For N = 3, the transition flow regime of SC packed beds covers the range of 260 < Re < 430. The effect of tube to particle diameter ratio (N = 3, N = 4 and N = 5) on flow transition is also discussed. The transition flow regime occurs at Reynolds number ranging from 170 to 390 for most electrodes in simple cubic packed beds with N = 4 and N = 5. This may indicate that the tube to particle diameter ratios N has little influence on the flow transition in SC packed beds with N ≥ 4.