Impinging jet method

Wilson, A. D., Groffman, D. M., Powis, D. R. Scott, R. P. (1986a). An evaluation of the significance of the impinging jet method for measuring the acid erosion of dental cements. Biomaterials, 7, 55-60. 

Osborne et al., 1978) and the laboratory impinging jet method (Beech Bandyopadhyay, 1983 Wilson et a/., 1986a). 

In vitro studies by Wilson et al. (1986) using the impinging jet method show the EBA cement to be the least resistant of all the cement types to erosion in neutral solution. Clinical studies confirm this result and show that there is greater dissolution in the mouth than for other dental cements (Mitchem Gronas, 1978 Osborne et al., 1978 Andrews and Hembree, 1976 Shilling, 1977). Despite this, a clinical survey by Silvey and Myers... 

The laboratory impinging jet test for evaluating the acid erosion of dental cements is described in Chapter 10. Using this method with lactic acid-lactate solutions, Wilson et al. (1986b) found, for one cement, that the erosion rate was virtually zero at pH = 5 0, 0-38 % at pH = 4-0 and 5 7 % at pH = 2-7. For a range of cements Wilson et al. (1986a) found erosion rates varying from 3 0 to 5-7 % in lactic add solutions of pH = 2-1. The... 

The importance of chemical-reaction kinetics and the interaction of the latter with transport phenomena is the central theme of the contribution of Fox from Iowa State University. The chapter combines the clarity of a tutorial with the presentation of very recent results. Starting from simple chemistry and singlephase flow the reader is lead towards complex chemistry and two-phase flow. The issue of SGS modeling discussed already in Chapter 2 is now discussed with respect to the concentration fields. A detailed presentation of the joint Probability Density Function (PDF) method is given. The latter allows to account for the interaction between chemistry and physics. Results on impinging jet reactors are shown. When dealing with particulate systems a particle size distribution (PSD) and corresponding population balance equations are intro-... 

There is yet another method which also enhances transfer very efficiently, in which a stream is induced to impact a fixed wall surface, i.e., the impinging jet (IJ). Obviously, the flow configuration and the action of stream impingement of IJ are totally different from the impinging streams, although it uses also the term impinging ... 

Graphical methods can be used to extract information concerning mass transfer if the data are collected under well-controlled hydrodynamic conditions. The systems described in Chapter 11 that are imiformly accessible with respect to convective diffusion would be appropriate. The analysis would apply to data collected on a rotating disk electrode as a function of disk rotation speed, or an impinging jet as a function of jet velocity. 

As discussed in Section 9.1.2, reverse addition has been a time-honored method of producing small crystals. It typically suffers from broad size distribution and high impurity content (if present in the mother liquors) because of the excessive supersamration gradients encountered by the inlet solution. In the present example, the final product contained too much of an undesired impurity. This product will also be compared to that from the impinging jet operation in the discussion below. 

In-line methods are applicable to reactive crystallization with systems with a relatively fast reaction rate and a short nucleation induction time. There are two in-line devices that have potential for these applications impinging jets and vortex mixers. The reader is referred to Chapter 9 for a discussion of impinging jets as applied to antisoivent crystallization. The application to reactive crystallization is similar—creation of high supersaturation in a... 

Waves form on the surface of the sheet and grow until the sheet breaks up into small droplets. The generated spray has an elliptical cross section with its major axis in the plane of the liquid sheet. The sizes of the droplets formed from the impinging jet atomizers are directly related to the thickness of the liquid sheet. Generally, the is inversely proportional to the radial distance from the impingement point and other parameters. This chapter provides a description of the characteristics of liquid sheets formed by impinging jets and provides methods to determine average droplet sizes produced by such nozzles. 

Flow Rate Measurements, Methods, Fig. 15 Schematic representation of the flapping motion of the jet column for a microflow sensor with a convergent nozzle and a V-shaped plate. Periodic flapping motion occurs when the impinging jet reaches the V-shaped plate, (a) Jet column flaps upward, and (b) jet column flaps downward [10]... 

However, most explicit kinetic equations proposed in the literature are based on rather simple adsorption models which have no relevance for polymer adsorption. In this paper we will therefore first consider mass transfer-limited polymer adsorption and desorption rates from a theoretical point of view. We will then turn our attention to measurements which were designed in such a way as to enable accurate control over the mass transfer rate, so that data can be meaningfully analyzed. We used two different methods. The first is reflectometry combined with impinging-jet flow in order to measure adsorbed mass as a function of time.This... 

It should be emphasized that this chapter is concerned exclusively with the effect of antifoam concentration on foam generation. We are mainly concerned here with foam generation by air entrainment using, for example, shaken, rotated, or stirred vessels and impinging jets, etc. Perhaps the majority of foam control problems for which antifoams are employed concern foam generation by such methods. They are... 

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