Transfer unit, number

Use the HTU-NTU (height of transfer unit-number of transfer units) method to determine the height of packing in ... 

Number of gas phase mass transfer units Number of liquid phase mass transfer units Number of overall gas phase mass transfer units Rate of mass transfer of component i Pressure... 

Gj /k aPh.3.s the dimension of length or height and is thus designated the gas-phase height of one transfer unit, The integral is dimensionless and indicates how many of these transfer units it takes to make up the whole tower. Consequently, it is called the number of gas-phase transfer units, N. Equation 40 may therefore be written as... 

Hq and aie called the overall gas-phase height of a transfer unit and the number of overall gas-phase transfer units, respectively. In the case of a straight equiUbrium line, is often neady concentration-independent as explained earher. In such cases, use of equation 47 is especially convenient... 

Equation 55 is a tigoious expression for the number of overall transfer units for equimolar counterdiffusion, in distillation columns, for instance. 

NTU p is the "exterior apparent" overall gas-phase number of transfer units calculated neglecting axial dispersion simply on the basis of equation 56, whereas NTU stands for the higher real number of transfer units (Nq ) which is actually required under the influence of axial dispersion. The correction factor ratio can be represented as a function of those parameters that are actually known at the outset of the calculation... 

In these equations S denotes the stripping factor, Equation 77 is only vaUd for a sufftciendy high number of transfer units so that the correction... 

Rate of Mass Transfer in Bubble Plates. The Murphree vapor efficiency, much like the height of a transfer unit in packed absorbers, characterizes the rate of mass transfer in the equipment. The value of the efficiency depends on a large number of parameters not normally known, and its prediction is therefore difficult and involved. Correlations have led to widely used empirical relationships, which can be used for rough estimates (109,110). The most fundamental approach for tray efficiency estimation, however, summarizing intensive research on this topic, may be found in reference 111. 

To estimate the number of transfer units for design, the following empirical correlations which were derived from efficiency measurements employing a variety of trays and operating conditions under the aforementioned assumptions are recommended (111) ... 

This term is a measure of the unit s length. Sometimes it is referred to as the number of transfer units. This simply says that the optimum pressure drop increases as the heat exchanger gets longer, ie, has more transfer units. The forms of F, and F both foUow from the fact that in turbulent flow the... 

In order to determine the packed height it is necessary to obtain a value of the overall number of transfer units methods for doing this are available for binary systems in any standard text covering distillation (73) and, in a more complex way, for multicomponent systems (81). However, it is simpler to calculate the number of required theoretical stages and make the conversion ... 

A/og Number of overall gas-pbase mass-transfer units Dimensionless Dimensionless... 

NTU Number of transfer units (general) Dimensionless Dimensionless... 

NTU (Number of Transfer Units) The NTU required for a given separation is closely related to the number of theoretical stages or plates required to cariy out the same separation in a stagewise or plate-type apparatus. For equimolal counterdiffusion, such as in a binary distillatiou, the number of overall gas-phase transfer units Nqg required for changing the composition of the vapor stream from yi to yo is... 

The number of transfer units in any direct dryer is given by... 

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