Local flow regime and bubble size distribution in the slender particle-containing scrubbing-cooling chamber of an entrained-flow gasifier

Local Distributions of Bubble Velocity and Interfacial Area in the Slender Particle-Containing Scrubbing–Cooling Chamber of an Entrained-Flow Gasifier

“…Mean bubble diameter was calculated by eq 5, 68 where D and P b (D) are the equivalent bubble diameter and size distribution of bubbles touching the probe, respectively. 13 Recently, Besagni and Deen 69 proposed a new comprehensive correlation for the bubble shape and we compared our experimental data with the new correlation proposed by Besagni and Deen in Supporting Information S3. As shown in Figure 4a, rising bubble velocity distributions gradually transform from wide peak distributions in region 1 to sharp peak distributions in region 3, especially at high superficial gas velocity.…”

“…Sampling time and frequency have been validated in Peng et al 13 as well. It is worth noting that Worosz et al 63 found that the interfacial area measurement strongly depends on the selection of the sampling frequency.…”

“…The three scaling-up criteria we used in this study were proposed by Wilkinson et al 16 The critical value of the dimensionless diameter, D H *, in criterion 1 we adopted in this study is the same with those in our previous studies. 12,13 The D H,Cr * should be no less than 30 (D H,Cr * ≥ 30), which was proposed by Kataoka and Ishii 58 (this critical value was also adopted by Pagan et al 59 ). It is slightly different from that of the D H,Cr * ≥ 52 proposed by Wilkinson et al We also notice that some researchers also defined this critical value as 40, such as Schlegel et al 60 In this study, the upper part of the scrubbing−cooling chamber is an annular bubbling bed.…”

“…Air, tap water, and nylon fiber particles were used for gas−liquid− solid three-phase and the specifications of nylon fiber particles are shown in Table 1. The detailed operation processes are the same as Peng et al 13 The bubble-breaking plate structure and radial measurement points, (r/R is the ratio between the radial distance, i.e., from the measuring point to the center of the column and the radius of the column), as shown in Figure 1b. At the initial static liquid level of 540 mm, radial bubble velocities, chord lengths, and local gas holdups were measured at different superficial gas velocities (calculated by the annular cross-sectional area) (U g = 0.074−0.37 m/s), fiber volume fractions (c s = 0−0.03%), and fiber aspect ratios (a r = 20−50).…”

Flow Characteristics of the Vertical Turbulent Falling Film at High Reynolds Numbers

“…Falling liquid films are widely used in many thermal systems, including falling-film evaporators, scrubbing-cooling chambers, condensers, and nuclear reactors, for the advantages of high heat and mass transfer coefficient, little temperature difference, small flow, and simple structure. As an efficient heat transfer method, falling film systems are usually used under the harsh conditions of high temperature, multiphase flow, and complex interface, which makes that the flow behaviors of falling films so complicated.…”