Effects of Fuel Input on Pulsation Reactor Behavior—An Experimental Study

Abstract

Material treatment in pulsation reactors (PR) brings the possibility of synthesizing powdery products with advantageous properties, such as nanoparticle sizes and high specific surface areas, at an industrial scale. The extraordinary material properties can be ascribed to special process parameters in a PR, primarily the periodically varying conditions and the consequently enhanced heat and mass transfer between the medium and the particles of the material. Understanding the connections between the PR operation parameters, such as fuel and air intake or PR geometry, and the resulting process parameters (temperature distribution, flow velocity and pressure field, and frequency of the pulsations) is essential to enabling a controllable treatment process. Despite the long history of pulsation reactor technology, many connections and dependencies remain unclear. Thus, the influence of the fuel (and air) supply on the pulsation reactor behavior is experimentally examined in this study. The investigated PR characteristics and process parameters are primarily those that have an impact on the heat and mass transfer, i.e., the temperature distribution, flow velocity, and pressure field, and frequency of the pulsations. In addition to these, the harmonic distortion of the oscillations and the heat losses are evaluated.

Experimental Investigation of a Pulsation Reactor via Optical Methods

“…The center area of the flame (Area 2 in Figure 17) was selected for two reasons: (1) flame propagation initiates in the central region and expands outward, accompanied by significant heat release during combustion, and (2) the flam's center generally exhibits greater stability compared to the flame edges, making it more representative of the main speed and direction of flame motion. Theoretically, the flame velocity exhibits a nonlinear relationship with the parameter λ eq within the range of 0.76 to 2.08 [47] (the range of air-fuel equivalence ratio of stable pulsation investigated by Dostál et al [8]). Based on the experimental data in Figure 17, the flame velocity will gradually increase when λ eq is low.…”

“…In Figure 2, these are represented by the category called Material. The frequency of the present pressure wave depends (besides temperature, [11] determining the speed of sound in the particular medium) on the geometry of the combustion chamber and the tailpipe [8]. Together, they form the Helmholtz resonator system, which is described in more detail in Section 1.2.…”

“…While in most cases the glow igniter was used, the PR operated without any glow ignition at OP6. In addition, in order to observe and analyze the flame under stable pulsation conditions, all of the selected operating points are subject to such conditions, which are presented by Dostál et al [8]. Each operating point corresponds to a time duration of 1-2 s. As a result, approximately 55 cycles of image data were obtained for each operating point.…”

“…Overview of the measured operation points for the flame. The values of power density input and air-fuel equivalence ratio are calculated by Dostál et al[8].…”