Reaktoren für Fluid-Feststoff-Reaktionen: Pulsationsreaktoren

Hoffmann, Claudia; Ommer, Matthias

doi:10.1007/978-3-662-56444-8_50-1

Cited by 3 publications

(5 citation statements)

References 15 publications

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“…The particular process conditions in the TP allow for a variety of continuous material treatment applications, e.g., drying, calcination, and annealing [2,3]. However, PRs are primarily recognized for the possibility of synthesizing ultra-fine powdery products with advantageous properties at an industrial scale [4][5][6]. For example, Heidinger et al [7] describe the synthesis of zirconia and silica nanoparticles in the PR.…”

Section: Pulsation Reactors For Materials Treatmentmentioning

confidence: 99%

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Experimental Investigation of a Pulsation Reactor via Optical Methods

Zhang,

Dostál,

Heidinger

et al. 2024

Processes

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Material treatment in pulsation reactors (PRs) offers the potential to synthesize powdery products with desirable properties, such as nano-sized particles and high specific surface areas, on an industrial scale. These exceptional material characteristics arise from specific process parameters within PRs, characterized by the periodically varying conditions and the resulting enhanced heat and mass transfer between the medium and the particulate material. Understanding flame behavior and the re-ignition mechanism is crucial to controlling the efficiency and stability of the pulse combustion process. In order to accomplish this objective, an investigation was conducted into flame behavior within the combustion chamber of a Helmholtz-type pulsation reactor. The study was focused on primarily analyzing the flame propagation process and examining flame velocity throughout the operational cycle of the reactor. Two optical methods—natural flame luminosity (NFL) and particle image velocimetry (PIV)—were applied in related experiments. An analysis of the NFL measurement data revealed a correlation between the intensity of light emitted by the pulsed flame and the air-fuel equivalence ratio (range from 0.892.08 in this study). It is observed that a lower air-fuel equivalence ratio leads to higher flame luminosity in the PR. In addition, in order to study the parameters related to system stability and energy transfer efficiency, this study also focuses on the local velocity field measurement method and an example of a fluid flow result in a combustion chamber by using a phase-locked PIV measurement system upgraded from a classic PIV system. The presented results herein contribute to the characterization of flame propagation within a pulsation reactor, as well as in pulsatile flows over one working cycle in a broader context, with flow velocity in the center of the combustion chamber ranging from 1.55m/s. Furthermore, this study offers insights into the applicable experimental methodologies for investigating the intricate interplay between flames and flows within combustion processes.

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Section: Pulsation Reactors For Materials Treatmentmentioning

confidence: 99%

“…F,k represents the mass fractions of the combustible components contained in the fuel. Provided that the fuel composition is known, its mass flow rate is determined by applying relation ( 4) to (5) as…”

Section: Investigated Pr Characteristics Related To This Studymentioning

confidence: 99%

Experimental Investigation of a Pulsation Reactor via Optical Methods

Zhang,

Dostál,

Heidinger

et al. 2024

Processes

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“…A steady flow is present in an entrained flow reactor, in contrast to the pulsating flow in a PR. The incessant periodic variation in the relative velocity between the gas and the particles (i.e., the periodically varying Reynolds number) causes an increase in the mean Nusselt number and consequently results in an improved convective heat transfer [17]. In the work by Dec and Keller [18], the mean Nusselt number for a pulsating flow was reported to be up to 2.5 times larger compared to a steady flow of the same mean Reynolds number.…”

Section: Materials Synthesis In a Pulsation Reactormentioning

confidence: 99%

“…Applying such a specific model for heat transfer is omitted here in order to focus on the concept itself, but all of the mainstream models predict an increase in heat transfer via the Nusselt number Nu(u(t)) with an increased slip velocity. Since the Nusselt number increases with increasing slip velocity, the pulsation leads to an improved heat transfer [17]. The criterion for the speed of the actual heating of the particle is the relaxation time τ T = d 2 ρ p c/12λ, with d being the diameter, c being the specific heat capacity of the particle, and λ being the thermal conductivity of the gas.…”

Section: Heat Transfer At Particles In Steady and Pulsating Flowsmentioning

confidence: 99%

Material Treatment in the Pulsation Reactor—From Flame Spray Pyrolysis to Industrial Scale

et al. 2022

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Current challenges in the areas of health care, environmental protection, and, especially, the mobility transition have introduced a wide range of applications for specialized high-performance materials. Hence, this paper presents a novel approach for designing materials with flame spray pyrolysis on a lab scale and transferring the synthesis to the pulsation reactor for mass production while preserving the advantageous material properties of small particle sizes and highly specific surface areas. A proof of concept is delivered for zirconia and silica via empirical studies. Furthermore, an interdisciplinary approach is introduced to model the processes in a pulsation reactor in general and for single material particles specifically. Finally, facilities for laboratory investigations and pulsation reactor testing in an industrial environment are presented.

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“…A rigid, spherical particle suspended in a harmonically oscillating one-dimensional flow is considered. This configuration can be found, for example, with ultrasonic levitators [1,2] or pulsation reactors [3][4][5]. In case the particle is fixed in position (or the particle executes harmonic oscillations in a fluid at rest), the interaction between the fluid and the particle as well as the resulting flow state is defined by two dimensionless numbers: the particle Reynolds number Re and the amplitude parameter .…”

Section: Introductionmentioning

confidence: 99%

Simple Particle Relaxation Modeling in One-Dimensional Oscillating Flows

2022

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The relaxation of a rigid particle suspended in a one-dimensional oscillating flow is calculated according to different drag models and the results are compared. Conditions are derived under which relaxation can be neglected or drag models can be substituted by simpler ones. This investigation is conducted analytically and graphically via the plane defined by the Reynolds number and amplitude parameter. This work matches various, mostly analytic drag models together to consider simple particle relaxation with a few, broad range input parameters and cover large parts of the plane spanned by Reynolds number and amplitude parameter.

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Reaktoren für Fluid-Feststoff-Reaktionen: Pulsationsreaktoren

Cited by 3 publications

References 15 publications

Experimental Investigation of a Pulsation Reactor via Optical Methods

Experimental Investigation of a Pulsation Reactor via Optical Methods

Material Treatment in the Pulsation Reactor—From Flame Spray Pyrolysis to Industrial Scale

Simple Particle Relaxation Modeling in One-Dimensional Oscillating Flows

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