Nozzle orifice diameter

Fig. 9.2. The vibration frequency required to generate drops is determined by the stream velocity and the nozzle orifice diameter. Faster drop generation permits faster cell flow rate without enclosing significant numbers of multiple cells in single drops.

The powder obtained in experiment 15 was collected in the bag of the expansion vessel. Its characteristics are 7peak = 304K, Tend-set = 306.3 K and A/ fus = 120.3 Jg"1. This form V powder was white, light, with regular individual particles and was free-flowing. Nearly all experiments were achieved with the following conditions nozzle orifice diameter < 340 pm, 298 < T < 308 K, P > 20 MPa and 0.5 < Pi < 4 MPa led to the same kind of form V powder collected in the expansion vessel (7). A typical example of this kind of particle is shown on Fig. 4. It is made of an agglomeration of smaller particles. 

Fig. 5 Stroboscopic images of microcapsule formation via midair collision between two component liquids (scale bar = 100 pm) (A) and bright-field microscope images of microcapsules (B). The left and streams are 0.25% alginate solution and 4% PLGA solution, respectively. The nozzle orifice diameter d = 60 pm volumetric flow rate Q = 0.6 ml/min and forcing frequency / = 10.6 kHz. (From Ref...

It has been shown that during the spray-drying process the effects of nozzle orifice diameter and atomization air flow control the droplet size during atomization however, it has also been demonstrated that increasing feed concentration results in... 

Authors differ with respect to the duration of each stage of the process, the process mode (batch or semibatch), the capillary/nozzle, and so on. The nozzle orifice diameter can vary from 20 to 760 pm. As detailed next, some authors have modified the introduction device to improve the dispersion and to enhance mass transfer. 

Molding machine clamping pressure (tons) Nozzle orifice diameter (mm)... 

Diffusers E and C of Bhutada and Pangarkar (1987) with multiorifice nozzles. Orifices diameter varied from 0.003 to 0.006 m. Pitch 1 xDjj to 2xDjj. Other details the same as Bhutada and Pangarkar (1987). 

For a steam rate of 50 Ib/hr, the resulting relation for nozzle orifice diameter is ... 

Among the pCPPs of the spray drying step, the risk assessment identified feed concentration (Cfeed), feed pressure (Pfeed), outlet temperature (Tout), condenser temperature (Pcond), and nozzle orifice diameter (Dnoz) as the highest-ranked ones. 

Fig. 8.32 Atomization model predictions Influence of nozzle orifice diameter on droplet size and throughput, Pfeed, ranged from 30 to 100 bar in both nozzles...

The ability to control the particle size and density of particles for inhalation was investigated using lactose solutions atomized with a two-fluid nozzle and dried in a laboratory scale dryer. It was found that droplet size during atomization was affected by nozzle orifice diameter and atomization airflow but not by feed concentration. However, dried particle size was influenced by feed concentration and it was suggested that the shell thickness of the hollow particles increased with increasing feed concentration (39). 

Make the machine nozzle orifice diameter of similar size to the channels in the hot runner manifold... 

The resulting motion of the beam is detected by the pneumatic nozzle amphfier, which, by proper sizing of the nozzle and fixed orifice diameters, causes the pressure internal to the nozzle to rise and fall with vertical beam motion. The internal nozzle pressure is routed to the pneumatic relay. The relay, which is constructed like the booster relay described in the Valve Control Devices subsection, has a direct hnear input-to-output pressure characteristic. The output of the relay is the controller s output and is piped away to the final control element. 

Hydraulic diameter, or equivalent diameter, in. Orifice diameter, or nozzle opening, in. 

Cd = Discharge coefficient for orifice and nozzles CD = Diameter correction factor, vacuum flow, Figure 2-43 CD2 = Diameter correction factor, vacuum flow, Figure 2-43... 

D = Inside diameter of pipe, ft DH = Hydraulic diameter, ft d = Inside diameter of pipe, in. = d de = Equivalent or reference pipe diameter, in. dn = Hydraulic diameter, or equivalent diameter, in. dQ = Orifice diameter, or nozzle opening, in. 

P = beta ratio orifice diameter to pipe diameter (or nozzle inlet diameter) e = (epsilon) emissivity value... 

The simplest and most common device for measuring flow rate in a pipe is the orifice meter, illustrated in Fig. 10-7. This is an obstruction meter that consists of a plate with a hole in it that is inserted into the pipe, and the pressure drop across the plate is measured. The major difference between this device and the venturi and nozzle meters is the fact that the fluid stream leaving the orifice hole contracts to an area considerably smaller than that of the orifice hole itself. This is called the vena contracta, and it occurs because the fluid has considerable inward radial momentum as it converges into the orifice hole, which causes it to continue to flow inward for a distance downstream of the orifice before it starts to expand to fill the pipe. If the pipe diameter is D, the orifice diameter is d, and the diameter of the vena contracta is d2, the contraction ratio for the vena contracta is defined as Cc = A2/A0 = (d2/d)2. For highly turbulent flow, Cc 0.6. 

The observations made below are applicable mainly to wetted nozzles. At low gas flow rates, the effect of orifice diameter is such that the volume of the bubble is directly proportional to it (B3, D4, VI). At higher flow rates... 

The coefficient C in equation 30 is a function of two phenomena. First, the presence of viscous friction accounts for a small loss of energy. Nozzle orifice contraction results in discharge coefficients which range from 0.5 to 0.85. The coefficient falls in the upper portion of this range when the length of the nozzle is two or three times its diameter, and in the lower end of the range where the nozzle diameter is more than five times its length. 

The main variables in the operation of atomizers are feed pressure, orifice diameter, flow rate and motive pressure for nozzles and geometry and rotation speed of wheels. Enough is known about these factors to enable prediction of size distribution and throw of droplets in specific equipment. Effects of some atomizer characteristics and other operating variables on spray dryer performance are summarized in Table 9.18. A detailed survey of theory, design and performance of atomizers is made by Masters (1976), but the conclusion is that experience and pilot plant work still are essential guides to selection of atomizers. A clear choice between nozzles and spray wheels is rarely possible and may be arbitrary. Milk dryers in the United States, for example, are equipped with nozzles, but those in Europe usually with spray wheels. Pneumatic nozzles may be favored for polymeric solutions, although data for PVC emulsions in Table 9.16(a) show that spray wheels and pressure nozzles also are used. Both pressure nozzles and spray wheels are shown to be in use for several of the applications of Table 9.16(a). 

---