Efficiency, packing, poor

At about 50% (w/w), phase inversion takes place, and at COP concentrations beyond 50% the formation of LC-rich islands in an LC-poor matrix is observed. These islands have been described by several authors in the COP system [118] and in a blend consisting of a rigid rod and a semiflexible coil polymer [121]. The formation of these islands is mainly due to differences in viscosity and surface tension of LC-poor and LC-rich phases and the tendency to achieve efficient packing by orientation and the lowering of lateral distances of the anisotropic parts of a polymer. The LC-poor (= PC-rich) matrix has a higher melt viscosity than that of COP. In a shear field or under... 

Even if excellent equipment is used, but the sample is passed over a badly packed" column, separation efficiency is poor. Therfore, the goal is to pack the chromatographic bed as densely and... 

It was postulated that the markedly different effect of carborane derivatives on host s properties results from the poor packing and the larger size of the carborane units in the more densely packed tilted phase than in the orthogonal one (tilt of the smectic phase results in more efficient packing of molecules). The anomalous behavior of 49D (m = 1) in the FLC mixture, was ascribed to relatively strong intermolecular interactions between the dopant and the host, which would suppress molecular motions and result in the formation of a more ordered phase. A similar stabilization of the E phase in a 3 2 mixture of 28A and 28D was explained by interactions between the carborane and electron-rich benzene rings. ... 

The above results are based on data obtained for optimized designs and under ideal test conditions. To translate our findings to the real world, one must factor in liquid and vapor maldistribution, which is far more detrimental to the efficiency of packings than trays. In addition. one also must account for poor optimization or restrictive internals, which are far more detrimental to the capacity of trays than packings. We also have cited several other factors that need to be considered when translating the findings of our analysis to real-world towers. ... 

The packed GC column has a value for (og) of about 55 pi, whereas the high efficiency microbore LC column only 0.23 pi. It is clear that problems of extracolumn dispersion with packed GC columns are not very severe. However, shorter GC capillary columns with small diameters will have a very poor tolerance to extracolumn dispersion. In the same way, short microbore LC columns packed with small... 

Liquid distribution probablv phtys the most important part in the efficient o]veration of a packed tower. good packing from the process viewpoint can be rednced in effectiv eness bv poor liquid distribution across the to ) of its upper surface or the packing sections below mv feed inlet(s) oi rellitx inlets. 

In general, the largest size of packing that is suitable for the size of column should be used, up to 50 mm. Small sizes are appreciably more expensive than the larger sizes. Above 50 mm the lower cost per cubic metre does not normally compensate for the lower mass transfer efficiency. Use of too large a size in a small column can cause poor liquid distribution. 

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