In order to compute fluid flows in a transformable flow channel with deposition of fine particles using a level-set method, a re-initialization method for a time-varying level-set function (ϕ) describing the evolution of the geometrical shape of the sedimentation layer of fine particles was considered. It was shown that the choice of re-initialization method was very important to avoid non-physical deformation of ϕ. The re-initialization method was then applied to the problem with increments of ϕ (Δϕ), and net Δϕ was affected by the re-initialization method. To avoid this problem, we proposed a new re-initialization method that can maintain Δϕ. A multi-dimensional calculation of fluid flows with deposition of file particles could be implemented by using the proposed method.

Numerical analysis of the motion of ellipsoidal droplets in a stagnant liquid was performed by a front-tracking method. Drag coefficients of ellipsoidal droplets were determined using the projected areas and the terminal velocities obtained by numerical simulations. The drag coefficients based on the projected areas of ellipsoidal droplets were in good agreement with those predicted by the semi-empirical model for spherical droplets. In order to take into account the deformation of droplets, the aspect ratio of ellipsoidal droplets was correlated by the Reynolds and Eötvös numbers. Terminal velocities predicted by the combination of the proposed correlation equation of the aspect ratio and the drag model for spherical droplets were in good agreement with those obtained by numerical simulations.

This study proposed a reactor concept for CO₂ methanation, aiming to realize high CO₂ conversion (≥ 99%) and high heat recovery rate under low pressure and thermally self-sustained conditions. The reactor has two stages with intermediate removal of water, and the portion of H₂ is supplied at the second-stage reactor inlet while CO₂ is provided only at the first-stage reactor inlet. The heat carrier flows directly from the first-stage reactor outlet to the second-stage reactor inlet, and the heat carrier path also branches between the first and second stages, resulting in a reduced heat carrier flow rate in the second stage. The efficacy of the concept was evaluated at 200 kPa (G). The results show that both stages of the reactor can be thermally self-sustained by feeding H₂ stepwise, a high CO₂ conversion (≥ 99%) can be achieved by directly providing the heat carrier, and the heat recovery rate can be improved by branching the heat carrier path between the first and second stages. The responses of the conversion and the heat recovery rate at each stage to variation of the operational parameters (H₂ provision rate and heat carrier flow rate at each stage) were also examined. The results show that, in order to simultaneously achieve high CO₂ conversion and heat recovery rate, CO₂ conversion is required to be established with lowering the inlet heat carrier temperature in the second-stage reactor.

Solid solution catalysts composed of ZrO₂ and a group 2 metal oxide MgO, CaO or SrO were prepared by milling with a planetary mill and subsequent calcination, and the relationship between the properties of MgO–ZrO₂, CaO–ZrO₂ and SrO–ZrO₂ and their catalytic transesterification activities was examined. XRD and Raman spectroscopy helped to confirm that zirconia-based solid solution catalysts of MgO–ZrO₂, CaO–ZrO₂ and SrO–ZrO₂ were composed of multiple crystal phases of which the tetragonal or cubic phase was predominant. Analysis of CO₂-TPD and NH₃-TPD data suggested that the electronegativity of group 2 metals should affect the acidity of solid solution catalysts. Batch transesterification of rapeseed oil with ethanol at 473 K with solid solution catalysts having a 1 : 4 mol ratio of group 2 metal to Zr revealed that MgO–ZrO₂ with the weakest acidic strength of the catalysts tested had the highest catalytic activity. The results of characterization and batch transesterification with MgO–ZrO₂ catalysts having different Mg contents showed that the mole ratio of Mg to Zr determines the acidity of the catalyst. Thus, the acidity of the solid solution catalysts significantly affects the catalytic transesterification activity.

Flow process has attracted attention in the field of fine chemical synthesis. The well-designed immobilized catalyst is powerful tool to realize practical and efficient flow process. A macroporous monolith is a self-standing material with three-dimensional through-pores which ensures large surface area and high permeability. In this study, polyacrylamide-based macroporous monolith containing L-proline was developed and the porous properties of the monolith was evaluated. The internal structure of monolith was controlled by alcohol (ethanol, 1-butanol, 1-octanol, 1-dodecanol) used as porogen. In addition, the monolith was applied to asymmetric aldol addition reaction in flow system and achieved enantioselectivity of 61–74% ee at residence time of 12 h. This is the first example that achieved flow asymmetric synthesis using porous polymer monolith with L-proline.

A novel rotating coil-shaped spiral gas-solid contacting device was proposed. A cold model of a 1.5-cycle spiral structure was made by combining 180° elbows of half-octagonal shape using ID 24 mm transparent plastic tube. Pressure drop in the solid bed during gas feed was measured. Co-current flow and counter-current flow of gas were employed. Below a certain gas flow rate (threshold gas flow rate), pressure drop in the bed increased monotonically with increasing gas feed rate. However, when the gas flow rate exceeded the threshold, the pressure drop suddenly decreased. This sudden decrease in pressure drop is attributable to the gas passing through the channeling formed in the bed for co-current flow, and to the formation of a fluidized region in the vertical section for counter-current flow. The relationship between the maximum pressure drop observed for the co-current flow and particle-wall friction force or particle-particle friction force is discussed. For counter-current flow, the relationship between the superficial gas velocity at maximum pressure drop and minimum fluidizing velocity of the solids is discussed.