Experimental evaluation and dynamic modelling were presented for a liquid flow (H2O + NaOH tracer) on solid particles in a trickle bed reactor. One-dimensional dynamic mathematical model has been described to study th...Experimental evaluation and dynamic modelling were presented for a liquid flow (H2O + NaOH tracer) on solid particles in a trickle bed reactor. One-dimensional dynamic mathematical model has been described to study the gas-liquid-solid process in which the liquid phase with the NaOH tracer is treated as a continuum. The physical model has been analyzed, including the formulation of initial and boundary conditions and the description of the solution methodology. An experimental setup to measure the concentrations of the NaOH tracer has been performed. The concentration measurements of this NaOH tracer have been performed in a fixed be reactor on trickling flow of the liquid phase for a range of operating conditions. The axial dispersion (Dax) of the liquid phase, liquid-solid mass transfer (kLS) coefficient and partial wetting efficiency (fe) were chosen as the hydrodynamic parameters of the proposed mathematical model. Such parameters have been optimized with experimental measurents of the NaOH tracer at the exit of the trickle-bed reactor. The optimized parameters (Dax, kLS, and fe) were calculated simultaneously by using the theoretical model with minimization of the objective function. Results of the proposed mathematical model have been presented and compared as of the two experimental cases. These hydrodynamic parameters were fitted by means of the empirical correlations.展开更多
The intermittent nature of renewable resources requires for most applications the development of efficient and cost-effective technologies for steady supply of electrical energy.The storage of energy in the form of hy...The intermittent nature of renewable resources requires for most applications the development of efficient and cost-effective technologies for steady supply of electrical energy.The storage of energy in the form of hydrogen chemically bound within organic molecules(rather than physically as compressed gas or cooled liquid)represents an alternative approach that is attracting great research interest.Compared to other liquid organic hydrogen carriers(LOHCs),dimethyl ether(DME)appears to have the largest potential impact on society,especially if inserted in technological chains of CO_(2) sequestration and utilization,so to determine an effective mitigation of environmental issues,without any net effect on the carbon footprint.Specifically,the steps of H2 storage and H2 release can take place in two coupled chemical processes,constituted by the exothermic synthesis of DME via CO_(2) hydrogenation and the endothermic steam reforming of DME,respectively.Herein,the latest advances in the development of heterogeneous bifunctional and hybrid catalysts for the direct hydrogenation of CO_(2) to DME are thoroughly reviewed,with special emphasis on thermodynamics,catalyst design and process feasibility.Despite many aspects behind the mechanism of DME synthesis from H2-CO_(2) streams are still to be uncovered,the recent progress in the research on H2 release by DME steam reforming is increasing the interest for effectively closing this binary H2 loop,in view of future green deals and sustainable research developments.展开更多
The article is devoted to a problem of sedimentation of superfine aerosols with a characteristic size of particles, an order of values of micrometers. Acceleration of the sedimentation process is promoted by imposing ...The article is devoted to a problem of sedimentation of superfine aerosols with a characteristic size of particles, an order of values of micrometers. Acceleration of the sedimentation process is promoted by imposing of an acoustic field that leads to acceleration of coagulation of particles. Besides, pressure of the sound radiation directed down, accelerates gravitational sedimentation of an aerosol. The mathematical model is based on the Smolukhovsky’s equation, describing dynamics of change of distribution function by the sizes of aerosols particles taking into account ultrasonic influence, evaporation (for liquid aerosols) and sedimentation. Influence of introduction of an additional phase on coagulation and sedimentation speed is investigated. Results of a theoretical and experimental study of dispersion parameters and the sedimentation speed of superfine aerosols are presented.展开更多
We examine MHD processes arising in melts placed in vessels of circular and rectangular cross-sections under the action of amplitude-and-frequency modulated rotating magnetic field.It is established that besides the m...We examine MHD processes arising in melts placed in vessels of circular and rectangular cross-sections under the action of amplitude-and-frequency modulated rotating magnetic field.It is established that besides the mean turbulent flow,seven oscillations arise in the melt,whose frequency and amplitude depend on modulation parameters.展开更多
文摘Experimental evaluation and dynamic modelling were presented for a liquid flow (H2O + NaOH tracer) on solid particles in a trickle bed reactor. One-dimensional dynamic mathematical model has been described to study the gas-liquid-solid process in which the liquid phase with the NaOH tracer is treated as a continuum. The physical model has been analyzed, including the formulation of initial and boundary conditions and the description of the solution methodology. An experimental setup to measure the concentrations of the NaOH tracer has been performed. The concentration measurements of this NaOH tracer have been performed in a fixed be reactor on trickling flow of the liquid phase for a range of operating conditions. The axial dispersion (Dax) of the liquid phase, liquid-solid mass transfer (kLS) coefficient and partial wetting efficiency (fe) were chosen as the hydrodynamic parameters of the proposed mathematical model. Such parameters have been optimized with experimental measurents of the NaOH tracer at the exit of the trickle-bed reactor. The optimized parameters (Dax, kLS, and fe) were calculated simultaneously by using the theoretical model with minimization of the objective function. Results of the proposed mathematical model have been presented and compared as of the two experimental cases. These hydrodynamic parameters were fitted by means of the empirical correlations.
文摘The intermittent nature of renewable resources requires for most applications the development of efficient and cost-effective technologies for steady supply of electrical energy.The storage of energy in the form of hydrogen chemically bound within organic molecules(rather than physically as compressed gas or cooled liquid)represents an alternative approach that is attracting great research interest.Compared to other liquid organic hydrogen carriers(LOHCs),dimethyl ether(DME)appears to have the largest potential impact on society,especially if inserted in technological chains of CO_(2) sequestration and utilization,so to determine an effective mitigation of environmental issues,without any net effect on the carbon footprint.Specifically,the steps of H2 storage and H2 release can take place in two coupled chemical processes,constituted by the exothermic synthesis of DME via CO_(2) hydrogenation and the endothermic steam reforming of DME,respectively.Herein,the latest advances in the development of heterogeneous bifunctional and hybrid catalysts for the direct hydrogenation of CO_(2) to DME are thoroughly reviewed,with special emphasis on thermodynamics,catalyst design and process feasibility.Despite many aspects behind the mechanism of DME synthesis from H2-CO_(2) streams are still to be uncovered,the recent progress in the research on H2 release by DME steam reforming is increasing the interest for effectively closing this binary H2 loop,in view of future green deals and sustainable research developments.
文摘The article is devoted to a problem of sedimentation of superfine aerosols with a characteristic size of particles, an order of values of micrometers. Acceleration of the sedimentation process is promoted by imposing of an acoustic field that leads to acceleration of coagulation of particles. Besides, pressure of the sound radiation directed down, accelerates gravitational sedimentation of an aerosol. The mathematical model is based on the Smolukhovsky’s equation, describing dynamics of change of distribution function by the sizes of aerosols particles taking into account ultrasonic influence, evaporation (for liquid aerosols) and sedimentation. Influence of introduction of an additional phase on coagulation and sedimentation speed is investigated. Results of a theoretical and experimental study of dispersion parameters and the sedimentation speed of superfine aerosols are presented.
文摘We examine MHD processes arising in melts placed in vessels of circular and rectangular cross-sections under the action of amplitude-and-frequency modulated rotating magnetic field.It is established that besides the mean turbulent flow,seven oscillations arise in the melt,whose frequency and amplitude depend on modulation parameters.
