Electrospraying route to nanotechnology: An overview

Steels for bearings

Publisher Summary This chapter presents a discussion on jet impingement heat transfer. The chapter describes the applications and physics of the flow and heat transfer phenomena, available empirical correlations and values they predict, and numerical simulation techniques and results of impinging jet devices for heat transfer. The relative strengths and drawbacks of the Reynolds stress model, algebraic stress models, shear stress transport, and v 2 f turbulence models for impinging jet flow and heat transfer are compared in the chapter. The chapter provides select model equations as well as quantitative assessments of model errors and judgments of model suitability. The review of recent impinging jet research publications identified a series of engineering research tasks that are important for improving the design and resulting performance of impinging jets: (1) clearly resolve the physical mechanisms by which multiple peaks occur in the transfer coefficient profiles, and clarify which mechanism(s) dominate in various geometries and Reynolds number regimes, (2) develop a turbulence model, and associated wall treatment if necessary, that reliably and efficiently provides time-averaged transfer coefficients, (3) develop alternate nozzle and installation geometries that provide higher efficiency, meaning improved Nu profiles at either a set flow or set blower power, and (4) further explore the effects of jet interference in jet array geometries, both experimentally and numerically. This includes improved design of exit pathways for spent flow in array installations.

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Jet Impingement Heat Transfer: Physics, Correlations, and Numerical Modeling

Micro- and nanoparticle production by electrospraying

This chapter deals with capillary instability of straight free liquid jets moving in air. It begins with linear stability theory for small perturbations of Newtonian liquid jets and discusses the unstable modes, characteristic growth rates, temporal and spatial instabilities and their underlying physical mechanisms. The linear theory also provides an estimate of the main droplet size emerging from capillary breakup. Formation of satellite modes is treated in the framework of either asymptotic methods or direct numerical simulations. Then, such additional effects like thermocapillarity, or swirl are taken into account. In addition, quasi-one-dimensional approach for description of capillary breakup is introduced and illustrated in detail for Newtonian and rheologically complex liquid jets (pseudoplastic, dilatant, and viscoelastic polymeric liquids).

Handbook of Atomization and Sprays

Spray drying is used for the manufacture of many consumer and industrial products such as instant dairy and food products, laundry detergents, pharmaceuticals, ceramics, and agrochemicals. During spray drying, agglomerates of powder particles are formed which determine the instant properties of the powder. Agglomeration during spray drying is considered to be a difficult process to control. The main cause of this is the complex interaction of the process variables: the atomization process, the mixing of spray and hot air, the drying of suspension droplets and the collision of particles which might lead to coalescence or agglomeration. As a consequence, agglomeration during spray drying is operated by trial-and-error. In an EC–sponsored project, named the EDECAD projects, an industrially validated computer model, using CFD technology, to predict agglomeration processes in spray drying machines is developed. An Euler-Lagrange approach with appropriate elementary models for drying, collision, coales...

Simulation of Agglomeration in Spray Drying Installations: The EDECAD Project

A mathematical model for cooling and rapid solidification of molten metal droplets

Measurement of phase interaction in dispersed gas/particle two-phase flow

In the wide field of fluid mechanics and multiphase flows, particle characterization plays an important role for massmomentum- and energy-balances. Using the phase-Doppler-difference method for absolute measurements of the particle sizes and velocities from these data also predictions of the local particle fluxes and the particles' kinetic energy fluxes are possible. A description of the method will be given and the required optical and electronical equipment for these measurements and for the appropriate data presentation, will be discussed.

The Phase‐Doppler‐Difference‐Method, a New Laser‐Doppler Technique for Simultaneous Size and Velocity Measurements. Part 1: Description of the method

Using a piezoceramic tube and a continuous glass capillary, droplets in a diameter range between 10 μm and 100 μm can be generated. This corresponds to a volume of up to 0.6 pl. The velocity of the generated droplets depends on droplet size but is constant for each diameter. The liquid can be dosed as single droplet, as an accumulation of droplets or as a chain of droplets in a frequency range between 1 Hz up to 3 kHz. The lifetime of the droplets depends on droplet size and the chemical and physical properties of the dispersed liquid. In addition, for water droplets the humidity of the air near the droplet trajectory influences the lifetime of the droplets.

Klaus Bauckhage

Papers

Simulation of Agglomeration in Spray Drying Installations: The EDECAD Project

A mathematical model for cooling and rapid solidification of molten metal droplets

Measurement of phase interaction in dispersed gas/particle two-phase flow

The Phase‐Doppler‐Difference‐Method, a New Laser‐Doppler Technique for Simultaneous Size and Velocity Measurements. Part 1: Description of the method

Piezoelectric Droplet Generator for the Calibration of Particle-Sizing Instruments