Bubble determination

The major advantage of film blowing is the ease with which biaxial orientation can be introduced into the film. The pressure of the air in the bubble determines the blow-up and this controls the circumferential orientation. In addition, axial orientation may be introduced by increasing the nip roll speed relative to the linear velocity of the bubble. This is referred to as draw-down. 

Bubbles are critical in manufacturing in the food industry. The stability and size of the bubbles determines the taste and the looks of the product. In industry, much research has been done on the factors that control bubble formation and stability. This is of special interest in the production of ice cream, where air bubbles are trapped in frozen material. 

The term food colloids can be applied to all edible multi-phase systems such as foams, gels, dispersions and emulsions. Therefore, most manufactured foodstuffs can be classified as food colloids, and some natural ones also (notably milk). One of the key features of such systems is that they require the addition of a combination of surface-active molecules and thickeners for control of their texture and shelf-life. To achieve the requirements of consumers and food technologists, various combinations of proteins and polysaccharides are routinely used. The structures formed by these biopolymers in the bulk aqueous phase and at the surface of droplets and bubbles determine the long-term stability and rheological properties of food colloids. These structures are determined by the nature of the various kinds of biopolymer-biopolymer interactions, as well as by the interactions of the biopolymers with other food ingredients such as low-molecular-weight surfactants (emulsifiers). 

The blown products, such as upward blown film, are basically natural for providing orientation (Figure 5.19). The blow-up ratio determines the degree of circumferential orientation, and the pull rate of the bubble determines the longitudinal orientation. 

While the interfacial tension and the buoyancy of the bubble determine the sliding speed of an attached bubble, the flow rate of air determines the frequency of creating a sliding bubble. Figures 27.12 and 27.14 show the influence of the flow rate of air on the detachment of sliding bubbles on the surface. In the case shown in... 

When breakdown is initiated in water, vapor bubbles are generated, which first expand and later collapse. The total time of expansion and collapse of these bubbles determines the repetition rate at which high voltage switches can be operated. The transparency of the water decreased with time during the discharge treatment of the liquid. 

Reference was made previously to three zones of reaction. The pressure Py, inside the bubble determines the zone in which the reaction occurs. High Pf, values correspond to reaction in zone 1, and high Pi values to reaction in zone 2. For reaction to occur in zone 3 (the Weissler reaction, for instance), Pb should be high, and also the residence time of the radicals generated should not be so high in zones 1 and 2 that they react among themselves and neutralize any enhancing effect. 

The size of pores in a membrane can be established by forcing liquid through the membrane under pressure. The time for the appearance of the bubble determines the largest pore size in the membrane. The pressure necessary to produce a bubble can be reduced by using liquid mixtures that minimize the surface tension within the pore. 

One of the most important roles of bubbles one finds is in the food industry (such as ice-cream champagne and beer industry). The stability and size of the bubbles determine the taste and the looks of the product. Especially, in the case of champagne, both the size and the stability of bubbles have been found to determine the impact of taste and flavor. It has been estimated that in a bottle of volume 750 mL, there will be about 50 million bubbles (if the average radius of bubbles is 0.1 mm) (Birdi, 2010a). This is a very rough estimate. However, more accurate estimates have been made by using photography of bubbles, etc. In the wine industry, much research has been made on the... 

The mass transfer characteristics of bubbles determine the efficiency and the size of process equipment used to carry out a range of chemical processes. Such processes may involve the use of bubble columns and three-phase fluidized bed reactors. A range of polymer processes such as those associated with the manufacture of foamed plastics would also benefit from a better understanding of bubble dynamics and mass transfer. Consequently, some research effort has been directed at elucidating the role of the rheological complexities of the ambient medium on mass transfer to/from stationary and moving bubbles as well as of bubble swarms. 

The flow field above the nozzle can be classified broadly into two regions the momentum region near the nozzle and the buoyancy region far from the nozzle [32]. In the former region, the inertial force of the injected gas governs the flow field, while the buoyancy force acting on the bubbles determines the latter. The two regions share a boundary at approximately z = 100 x 10 m. 

The stability of thin liquid films on solid surfaces is a major topic both in fundamental and in applied science. In flotation, the aqueous film formed between a particle and an approaching bubble determines the interaction and thus the efficiency of the process [695, 753, 813, 814]. Polymer films preserve, isolate, or decorate materials [815-820]. Thin metal films in microelectronics serve as electrodes [821-823]. When such films dewet, a solid surface complex pattern is formed (Figure 7.15) [824]. 

Determination of the concentration profile around each nucleated bubble Determined by solving the diffusion equation Approximated by a 4 order polynomial Determined by solving the difiusion equation... 

The computer subroutines for calculation of vapor-liquid equilibrium separations, including determination of bubble-point and dew-point temperatures and pressures, are described and listed in this Appendix. These are source routines written in American National Standard FORTRAN (FORTRAN IV), ANSI X3.9-1978, and, as such, should be compatible with most computer systems with FORTRAN IV compilers. Approximate storage requirements for these subroutines are given in Appendix J their execution times are strongly dependent on the separations being calculated but can be estimated (CDC 6400) from the times given for the thermodynamic subroutines they call (essentially all computation effort is in these thermodynamic subroutines). 

For mixtures, the calculation is more complex because it is necessary to determine the bubble point pressure by calculating the partial fugacities of the components in the two phases at equilibrium. 

Once the bubble point is reached (at point B), the first bubble of ethane vapour is released. From point B to C liquid and gas co-exist in the cell, and the pressure is maintained constant as more of the liquid changes to the gaseous state. The system exhibits infinite compressibility until the last drop of liquid is left In the cell (point C), which is the dew point. Below the dew point pressure only gas remains in the cell, and as pressure is reduced below the dew point, the volume increase is determined by the compressibility of the gas. The gas compressibility is much greater than the liquid compressibility, and hence the change of volume for a given reduction in pressure (the... 

The experiment could be repeated at a number of different temperatures and initial pressures to determine the shape of the two-phase envelope defined by the bubble point line and the dew point line. These two lines meet at the critical point, where it is no longer possible to distinguish between a compressed gas and a liquid. 

The value of the compresjiibility of oil is a function of the amount of dissolved gas, but is in the order of 10 x 10" psi" By comparison, typical water and gas compressibilities are 4x10" psi" and 500 x 10" psi" respectively. Above the bubble point in an oil reservoir the compressibility of the oil is a major determinant of how the pressure declines for a given change in volume (brought about by a withdrawal of reservoir fluid during production). 

The collection of representative reservoir fluid samples is important in order to establish the PVT properties - phase envelope, bubble point, Rg, B, and the physical properties - composition, density, viscosity. These values are used to determine the initial volumes of fluid in place in stock tank volumes, the flow properties of the fluid both in the reservoir and through the surface facilities, and to identify any components which may require special treatment, such as sulphur compounds. 

The ease with which small gas bubbles can escape from the liquid phase is determined by the liquid viscosity higher viscosities imply longer residence times. Typical residence times vary from, some 3 minutes for a light crude to up to 20 minutes for very heavy crudes. 

Small drops or bubbles will tend to be spherical because surface forces depend on the area, which decreases as the square of the linear dimension, whereas distortions due to gravitational effects depend on the volume, which decreases as the cube of the linear dimension. Likewise, too, a drop of liquid in a second liquid of equal density will be spherical. However, when gravitational and surface tensional effects are comparable, then one can determine in principle the surface tension from measurements of the shape of the drop or bubble. The variations situations to which Eq. 11-16 applies are shown in Fig. 11-16. 

Fig. X-8. Use of sessile drops or bubbles for contact angle determination.

The axisymmetric drop shape analysis (see Section II-7B) developed by Neumann and co-workers has been applied to the evaluation of sessile drops or bubbles to determine contact angles between 50° and 180° [98]. In two such studies, Li, Neumann, and co-workers [99, 100] deduced the line tension from the drop size dependence of the contact angle and a modified Young equation... 

Ammonia is conveniently obtained from a cylinder of the Uquefled gas the cylinder must be equipped with a reducing valve. The rate of flow of the gas may be determined by passage through a bubble counter containing a small volume of concentrated potassium hydroxide solution (12 g. of KOH in 12 ml. of water). A safety bottle should be inserted between the cylinder and the reaction vessel. 

The purity of a pharmaceutical preparation of sulfanilamide, C6H4N2O2S, can be determined by oxidizing the sulfur to SO2 and bubbling the SO2 through H2O2 to produce H2SO4. The acid is then titrated with a standard solution of NaOH to the bromothymol blue end point, where both of sulfuric acid s acidic protons have been neutralized. Calculate the purity of the preparation, given that a 0.5136-g sample required 48.13 mL of 0.1251 M NaOH. 

The concentration of SO2 in atmospheric samples can be determined by bubbling a sample of air through a trap containing H2O2. Oxidation of SO2 by H2O2 results in the... 

As an example of the quantitative testing of Eq. (5.47), consider the polymerization of diethylene glycol (BB) with adipic acid (AA) in the presence of 1,2,3-propane tricarboxylic acid (A3). The critical value of the branching coefficient is 0.50 for this system by Eq. (5.46). For an experiment in which r = 0.800 and p = 0.375, p = 0.953 by Eq. (5.47). The critical extent of reaction, determined by titration, in the polymerizing mixture at the point where bubbles fail to rise through it was found experimentally to be 0.9907. Calculating back from Eq. (5.45), the experimental value of p, is consistent with the value =0.578. 

Spectroscopic Probes of Cavitation Conditions. Determination of the temperatures reached ia a cavitating bubble has remained a difficult experimental problem. As a spectroscopic probe of the cavitation event, MBSL provides a solution. High resolution MBSL spectra from sUicone oU under Ar have been reported and analy2ed (7). The observed emission comes from excited state has been modeled with synthetic spectra as a... 

Hence the point efficiency Hqq may be computed if both and in the bubbling area are known. These paiameteis are determined by the prevailing... 

---