Nozzle arrays

As for oil and gas, the burner is the principal device required to successfully fire pulverized coal. The two primary types of pulverized-coal burners are circular concentric and vertical jet-nozzle array burners. Circular concentric burners are the most modem and employ swid flow to promote mixing and to improve flame stabiUty. Circular burners can be single or dual register. The latter type was designed and developed for NO reduction. Either one of these burner types can be equipped to fire any combination of the three principal fuels, ie, coal, oil and gas. However, firing pulverized coal with oil in the same burner should be restricted to short emergency periods because of possible coke formation on the pulverized-coal element (71,72). 

By feed of a fluid through a nozzle array, which is a plate with many tiny holes, so-called micro-plume injection into a micro channel can be achieved [51, 147]. Typically, the micro channel s floor is perforated in a section in this way and a closed-channel fraction follows for completion of mixing. Large specific interfaces can in principle be achieved depending on the nozzle diameter. This mixing concept benefits from conceptual simplicity and fits well to existing MEMS techniques. Furthermore, it consumes less footprint area and therefore does not create much dead space, which is one of the prime requirements during pTAS developments. 

M 94] [P 86] By means of fluorescence imaging, it could be shown that mixing is only completed in a downstream section below the mixing chamber and the nozzle-array section [54], This is explained by the comparatively low interfacial enlargement on direct collision. 

A 2-liter stainless steel vessel, partially filled with I2 crystals, was connected directly to the secondary He feed supply line of a supersonic chemical laser. A complete description is given in a separate paper.- The laser cavity had viewing windows on top and bottom so that the nozzle array could be viewed in a direction perpendicular to the optical axis. The pump laser was a Spectra-Physics Model 170-03 Ar+ laser equipped with an intracavity etalon. 

The AERx, developed by Aradigm (Hayward, CA), is a metered dose liquid inhaler designed to deliver various pharmaceutical compounds to the peripheral lungs. The system, as shown in Fig. 10, consists of a unit dose disposable container equipped with a nozzle array, a piston assembly, and electronics associated with breath actuation and compliance monitoring functions. ... 

The unit dose package contains the unit dose reservoir and an array of laser drilled nozzles, and the reservoir and nozzle array are connected with a heat seal that allows the formulation to flow from the reservoir to the nozzle after the seal is ruptured. The piston assembly consists of a motor, a piston, and a cam, which compresses the unit dose packet to extrude the drug under pressure through the nozzle array to produce aerosols suitable for inhalation. The AERx also has internal electronic monitoring, which measures the patient s inspiratory flow rate as a function of time of inspiration and triggers the dispensing of the dose at a predetermined inspiratory flow rate and time for... 

J. Chen and K. D. Wise, Nozzle array for inkjet printing, IEEE Trans. Electron Devices AA, 1401, 1997. S.-Y. Wu, A hybrid mass-interconnection method by electroplating, IEEE Trans. Electron Devices 25(10), 1401 1201, 1978. 

Currently the AERx system yields an emitted dose in a range of 60-75% of the dose inserted. A schematic diagram depicting the operation of AERx is shown in Fig. 10. The formulation is contained in a predosed blister with a volume of 50 pL and beside it a multilayer lid. The lid has a micromachined array of holes that are sealed from the blister. On pressurization of the blister, the seal breaks, which forces the liquid formulation through the nozzle array into the inhalation path. In order to reduce variability due to changes in ambient conditions, a temperature-controlling module is used to warm inspired air before the generation of aerosol. The authors believe that this last innovation is an impor-... 

Pautsch A, Shedd T (2005). Spray impingement cooling with single- and multiple-nozzle arrays. Part II visualization and empirical models. International Journal of Heat and Mass Transfer 48 3176-3184. 

B. Glassman, S. Kuravi, J. Du, Y. Lin, G. Zhao, L. Chow A fluid management system for a multiple nozzle array spray cooler, AIAA Paper No. 2004-2574, 37th AIAA Thermophysics Conference, Portland, June 28-July 1, 2004. 

De Heij et al. [4] designed a nozzle array to produce continuous droplets. The diameter of the nozzle is 50 pm. A digital stroboscope (Visit Video Stroboskop MOCRON-RT) was used to record the spraying process of droplets, and then the image processing software was used to calculate the diameter (Fig. 1). The accuracy of image measurement is 5 %. They have measured droplets from 0.1 to 0.7 nL, and the measurement accuracy is 0.1 pL. 

Plasma Etching, Fig. 9 SEM micrographs of (a) plane-view nozzle array with circuit layout and (b) cross section of one nozzle for a high-resolution inkjet head application... 

Selection. AH of these combinations of nozzles, arrays, and mechanisms offer benefits and drawbacks that are often connterintuitive to the end user. It is necessary, therefore, to test and evaluate the performance of the spray systems for the work type and working environment. Testing of performance mnst be evaluated in a carefully controlled trial or by comparison with a standardized ganging tool. 

For saving samples, reducing cross-contamination and operating fluids with smaller volume in microfluidic devices, designers hope that the dimensions of channels or tubes are as small as possible. When the characteristic dimension of channels decreases to the nanoscale, picoliter-scale flow will occur. De Heij et al. [4] designed a nozzle array of 50 xm diameter, which can produce... 

De Heij et al. [4] designed a nozzle array to produce continuous droplets. The diameter of the nozzle is 50 im. 

Flat products such as tiles, tissue, paper, textiles and wood veneer are often dried using nozzle arrays (Mujumdar, 2007). Figure 1.1 illustrates the basic principle of the drying process using a nozzle array. Ambient air of temperature is heated in... 

There are basically three possible designs of nozzle arrays which differ with regard to the spent flow of the air (Fig. 1.2). In a field of individual nozzles the aft-can flow unimpeded between almost all nozzles however, in a hole channel the air can flow only between those above. In a perforated plate the air can only continue to flow laterally and then escape. Hole channels and perforated plates are easier to produce than single nozzles, as they only require holes to be perforated. However, the heat transfer is the highest for nozzle fields and the lowest for perforated plates, as will be subsequently shown. 

For the design of the nozzle array the energy consumption needed for drying is essential. This is the energy for heating the air ... 

Fig. 1.2 Types of nozzle arrays, (a) Single-nozzle array (b) Hole channel (c) Perforated plate.

The fields of nozzles can be made from single nozzles, or hole channels, or from perforated plates with aligned or staggered arrangements, permitting a variety of geometric parameters. The heat transfer coefficient of nozzle arrays is therefore considered in more detail in the following. 

In Fig. 1.2a, the view of a nozzle array is shown with the impacted area. The nozzles may be arranged either in-line or staggered (in this figure the nozzles are in-line). In any case, each nozzle is influenced by the square area t of the nozzle pitch, and by using this area the average of the heat transfer can be determined. 

In comparison with respect to the Nusselt functions for single nozzle (Eqs 1.12 and 1.13), it is evident that the heat transfer in the nozzle array is higher than that of the single nozzle under the condition of similar Reynolds numbers. Regarding the average heat transfer, this increase is approximately 30%. 

In Fig. 1.13, the average heat transfer coefficient for a nozzle array is shown as a function of the discharge velocity for selected nozzle diameters. It can be seen that... 

Nozzle arrays are technically easier to manufacture in the form of hole channels than in the form of individual nozzles such a hole channel is shown, in principle, in Fig. 1.2b. 

Based on comparisons with the corresponding functions for the single-nozzle array, it is evident that the heat transfer in hole channels is less, by about 35%. 

Based on the given Nusselt fimctions for the required heat transfer coefficient in Eq. 1.9, nozzle arrays can now be designed. It is again assumed that the heat is predominantly transferred for evaporation, while the enthalpy to heat up the dry material is again neglected. First, an array of individual nozzles will be considered for which a distinct maximum in the heat transfer results at a pitch of t = 6d. Thus,... 

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