Transfer coefficient determination

Substituting the observed passage into Eq. (20-60) and rearranging yields Eq. (20-61). A plot of the LHS versus J data yields the mass-transfer coefficient from the slope, similar to the Wilson plot for heat transfer-coefficient determination ... 

Table 12.2 summarizes the more useful correlations for jD and jH that have been proposed by various investigators. The indicated correlations are quite consistent with one another in the regions where they overlap. Although the mass transfer coefficients determined from these correlations are not particularly large, they lead to high mass transfer rates when they are multiplied by the external surface area of the bed. For more detailed treatments of mass transfer... 

There is an approximately linear relationship between Rv and spin transfer coefficients determined from electron and nuclear magnetic resonance and neutron diffraction, i.e., a contraction of the unit cell accompanies the transfer of spin from transition metal to the ligands. 

K is the mass transfer coefficient, determined using Equation 3-18,... 

The transfer coefficient determines the symmetry - or lack thereof - of the current-potential curves they are symmetric for a = 1/2. For this reason the transfer coefficient is also known as the symmetry factor. 

For non-Newtonian liquids and suspensions, an apparent viscosity is determined using correlations which include power input and the Reynolds number. Scale-up comparisons based on heat generation data only were determined by comparison of results from RC1 experiments and from a 675-liter reactor [208]. In the experiments, a Bingham plastic fluid was used to determine the film heat transfer coefficient. This presents a worst case because of the low thermal conductivity of the Bingham plastic. Calculated inside film heat transfer coefficients determined in the RC1 tests were about 60% lower than the values determined in the pilot plant reactor, even though substantial effort was made to obtain both geometric and kinematic similarity in the pilot reactor. 

A mass transfer coefficient determined from some subsurface soil column elution studies was inverse log-linearly related to the octanol-water partition coefficient (i.e., K0Vf) for closely related compounds, and polarity in the molecule caused an additional decline in the mass transfer coefficient. 

Table 2.2 gives examples of mass transfer coefficients determined from both the single particle and fixed bed models for the evaporation of water from particles of the same diameter and density as in Table 2.1, assuming the diffusivity of water in air to be 3 x 10 m s h Once... 

Many parameters affect the mass transfer between two phases. As we discussed above, the concentration gradient between the two phases is the driving force for the transfer and this, together with the over-all mass transfer coefficient, determines the mass transfer rate. The influence of process parameters (e. g. flow rates, energy input) and physical parameters (e. g. density, viscosity, surface tension) as well as reactor geometry are summed up in the mass transfer coefficient. The important parameters for Kta in stirred tank reactors are ... 

As seen in Sect. 3.1, the transfer coefficient 0Erdey-Gruz and Volmer [32b] for the hydrogen electrode reaction, measures the symmetry of the free energy curves at this intersection in the transition state. In Fig. 5, it can be seen that the transfer coefficient determines the rate at which j grows exponentially with 77 for a constant n. 

The equipment heat transfer coefficient determined from a cooling (or heating) experiment performed in the industrial reactor containing a known amount of a compound with known physical properties. 

Each vertical tier consists of 3 tubes, and thus the heat transfer coefficient determined above Is valid for each of the four tiers. In other words, this value can be taken to be the average heat transfer coefficient for all 12 tubes. 

Individual transfer coefficients determined by geometry, mode (falling film, droplet formation) etc. 

The composition of the mobile phase also has an influence on the partition coefficients of inorganic substances and the separation efficiency. Concentrations of the mobile-phase constituents should provide partition coefficient values needed for the enrichment or separation of components under investigation. If a step-elution mode is used, partition coefficients higher than 10 and less than 0.1 are favorable for the enrichment of components into the stationary phase and their recovery into the mobile phase, respectively. Chemical kinetics factors may also play an important role in the separation of inorganic species by CCC [9]. It has been shown that the values of mass-transfer coefficients determine the... 

The mean annual flux of CO2 between the atmosphere and ocean, based on measurements of fccb in the ocean and atmosphere, and the gas exchange mass transfer coefficient determined from wind speed. From Takahashi eta/. (2002). (See Plate 8.)... 

The multicomponent mass transfer coefficients may be evaluated with the help of Eqs. 8.3.30 and 8.3.31 using the binary mass transfer coefficients determined above and the bulk gas-vapor composition. The result of the calculation is the following matrix ... 

It must be stressed that the individual mass-transfer coefficients, determined using Eqs (21)-(23), include both the diffusive and the osmotic transport components. Qf, and Qf, i, Qe, and Qe, i, Qr, and Qr,, represent the changes in the quantities of the solute, that is, in the concentrations and volumes between sampling time i, and i, i. Therefore, experimental determination of the osmotic pressure gradients. An, and calculation of osmotic mass-transfer coefficients, FQ, may be excluded. Overall mass-transfer coefficients of solute species through the BAHLM system are calculated using Eqs (8) and (9). 

After obtaining the original data it is necessary to correct the effect of the concentration polarization. In the mixed solutions it is not certain whether it is possible to use the mass transfer coefficient determined in a single solution. Here this value are used since no other correct method is known. Values of rejection, R, thus obtained are shown in Fig. 10 for vitamin Bi2 only and for the case with ovalbvimin gel layer. In this figure it is shown the rejection of different membrane are same due to the gel layer formation of ovalbumin. 

A one-shell pass and multiple-of-two-tube-passes heat exchanger is to be designed. Water flows at the rate of 60 kg/s and with velocity ZS m/s in tubes of 25 mm OD and 20 mm ID. The thermal conductivity of the tubes is 20 W/m-K. The inlet and outlet temperatures of the water are 120 °C and 65 °C, respectively. Oil flows through the shell at the rate of 120 kg/s and its temperature increases from 10 °C. The specific heat of oil is 2,100 J/kg-K. Assume the shell-side heat transfer coefficient to be one-tenth of the tube-side heat transfer coefficient. Determine the heat transfer area. 

For a circular duct, the hydraulic diameter is equal to its physical diameter. For a noncircular duct, it is convenient to use the hydraulic diameter to substitute for the characteristic physical dimension. However, for ducts with very sharp corners (e.g., triangular and cusped ducts), the use of the hydraulic diameter results in unacceptably large errors in the turbulent flow friction and heat transfer coefficients determined from the circular duct correlation. Other dimensions have been proposed as substitutes for hydraulic diameter. These equivalent diameters, provided for specific ducts only, will be presented elsewhere in this chapter. 

Equations (12.7.20) to (12.7.23) may be used to evaluate the parameter h. We begin by converting the convective heat transfer coefficient determined in Illustration 12.6, to British engineering units. 

The charge transfer coefficients determined from the slope of the Tafel lines were = 0.66 and = 1 — = 0.36. 

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