生物工程CAE工程 能源、化学工程、生物化学 反应器

1、Experiments and CFD simulation of ferrous biooxidation in a bubble column bioreactorComputers & Chemical EngineeringIn the present attempt a set of experiments and a 3D simulation using a commercially available computational fluid dynamics package (FLUENT) were adopted to investigate complex behavio

2、r involving hydrodynamics and ferrous biological oxidation in a gasliquid bubble column reactor. By combining the hydrodynamics and chemical species transport equations, the velocity field, air volume fraction and ferrous biooxidation rate in the column were simulated. The kinetic model proposed by

3、Nemati and Webb Nemati, M., & Webb, C. (1997). A kinetic model for biological oxidation of ferrous iron by Thiobacillus ferrooxidans. Biotechnology and Bioengineering, 53, 478486 was used to simulate the biooxidation rate in the column. Gasliquid interactions were modeled using an Eulerian model in

4、three dimensions. The effects of inlet air velocity and initial substrate (Fe2+) concentration on the velocity field, air volume fraction and biooxidation rate of ferrous iron in the column were investigated. To validate the model, simulation was compared with the experimental data in the presence o

5、f Acidithiobacillus ferrooxidans in an aerated column where the superficial gas velocity was adjusted between 0 and 0.5m/s. It was found that the initial ferrous concentration and the inlet air velocity had a pronounced effect on the ferrous biooxidation rate. The results indicated that the maximum

6、biooxidation rate can be obtained at superficial air velocity of 0.1m/s and initial ferrous concentration of 6.7g/L.Article Outline1. Introduction2. Experimental procedures 2.1. Materials and methods 2.1.1. Microorganism and medium2.1.2. Biooxidation procedure3. Mathematical modeling and numerical m

7、ethod 3.1. Kinetic model3.2. Eulerian approach3.3. Numerical implementation4. Results and discussion5. ConclusionCFD simulation of the hydrodynamics and reactions in an activated sludge channel reactor of wastewater treatmentChemical Engineering ScienceThis paper presents a complete CFD modelling of

8、 a wastewater gasliquid cross-flow reactor, taking into account hydrodynamics, mass transfer and biological reactions. Transfer processes, kinetics model and assumptions made are described in detail. The simulations have been successfully compared to experimental results obtained in a bench scale re

9、actor. Chemical oxygen demand (COD), nitrate, ammonium and oxygen concentrations have been measured along the length of the reactor and compared to the simulated profiles. A very good agreement has been obtained for the COD and nitrate concentration profiles. Agreement for the oxygen concentration p

10、rofile is reasonably good with respect to the experimental uncertainty. These results have been obtained without any adjustment of the kinetics parameters. The basics of a three-phase CFD model taking into account the transfer between flocs and wastewater, as well as the inhomogeneous concentration

11、of biomass due to the hydrodynamics of the reactor, are proposed as perspectives.Article Outline1. Introduction2. Pilot reactor and experimental details3. Hydrodynamics simulation and validation4. Transfer and transport modelling5. Kinetics modelling6. Simulation issues and assumptions for the biolo

12、gical CFD simulations 6.1. Grid constraints6.2. Modelling issues7. Comparison between experimental and simulation results8. Discussion and perspectives 8.1. Improvement of the existing tool8.2. Modelling of a three-phase kinetics model9. ConclusionAcknowledgementsApplications of computational fluid

13、dynamics (CFD) in the modelling and design of ventilation systems in the agricultural industry: A reviewBioresource TechnologyThe application of computational fluid dynamics (CFD) in the agricultural industry is becoming ever more important. Over the years, the versatility, accuracy and user-friendl

14、iness offered by CFD has led to its increased take-up by the agricultural engineering community. Now CFD is regularly employed to solve environmental problems of greenhouses and animal production facilities. However, due to a combination of increased computer efficacy and advanced numerical techniqu

15、es, the realism of these simulations has only been enhanced in recent years. This study provides a state-of-the-art review of CFD, its current applications in the design of ventilation systems for agricultural production systems, and the outstanding challenging issues that confront CFD modellers. Th

16、e current status of greenhouse CFD modelling was found to be at a higher standard than that of animal housing, owing to the incorporation of user-defined routines that simulate crop biological responses as a function of local environmental conditions. Nevertheless, the most recent animal housing sim

17、ulations have addressed this issue and in turn have become more physically realistic.Article OutlineNomenclature1. Introduction2. Methods of ventilating agricultural buildings3. Mathematical modelling of agricultural buildings 3.1. The advantages afforded by mathematical models3.2. The macro-model v

18、ersus micro-model description of ventilation4. Principles of CFD 4.1. Governing equations4.2. Numerical analysis4.3. Commercial CFD codes4.4. Performing a CFD analysis with commercial software 4.4.1. Pre-processing4.4.2. Solving4.4.3. Post-processing4.5. Representing the building geometry in CFD mod

19、els 4.5.1. Model dimensionality in mechanical ventilation4.5.2. Computational domain in natural ventilation5. Governing equations for describing the interaction between building, outdoor climate and indoor occupants 5.1. Turbulent air motion 5.1.1. Eddy viscosity models5.1.2. Reynolds stress closure

20、 models5.1.3. Large eddy simulation5.2. Air flow coupled with heat and mass transfer 5.2.1. Modelling buoyancy5.2.2. Modelling crop heat and mass transfer5.2.3. Modelling animal heat and mass transfer5.3. Flow resistance: porous media 5.3.1. Porous media convention5.3.2. The meteorological conventio

21、n5.3.3. Using a resistance coefficient5.3.4. Porous media assumption for solid obstructions5.4. The atmospheric boundary layer 5.4.1. Simulation with CFD5.4.2. The fluctuating of nature wind6. Validating the CFD predictions 6.1. Laboratory studies 6.1.1. Scaling for salt bath modelling6.1.2. Scaling

22、 for wind tunnel modelling6.1.3. Particle image velocitometry6.2. Full scale studies 6.2.1. Tracer gas techniques6.2.2. Sonic anemometry7. Computing the environment of greenhouses 7.1. Mono-span greenhouses 7.1.1. Tunnel greenhouses7.1.2. Pitched roof greenhouses7.1.3. Specialised single span greenh

23、ouses7.2. Multi-span greenhouses 7.2.1. Two-dimensional studies7.2.2. Three-dimensional studies8. Computing the environment of animal buildings 8.1. Poultry houses8.2. Pig houses 8.2.1. Pollutant distribution8.2.2. The thermal environment 8.2.2.1. Phenomenological studies8.2.2.2. Design studies8.3.

24、Cow houses9. Challenging issues confronting CFD modellers 9.1. Application issues 9.1.1. Dispersion modelling9.1.2. Modelling occupant movement9.1.3. CFD in ventilation control9.2. CFD modelling issues 9.2.1. Turbulence modelling9.2.2. Time stepping in transient simulations9.3. Enhancing CFD solutio

25、ns 9.3.1. The CFD mesh9.3.2. Observing the y+ criterion of turbulence models9.3.3. Mesh convergence study10. ConclusionsReferencesNumerical investigation of hydrodynamic and mixing conditions in a torus photobioreactorChemical Engineering ScienceIt is well-known that the response of photosynthetic m

26、icroorganisms in photobioreactor (PBR) is greatly influenced by the geometry of the process, and its cultivation parameters. The design of an adapted PBR requires understanding of the coupling between the biological response and the environmental conditions applied. Cells culture under well-defined

27、conditions are thus of primary interest. A particular lab-scale PBR has been developed for this purpose. It is based on a torus shape, that enables light to be highly controlled while providing a very efficient mixing, especially along the light gradient in the culture, that it is known to be a key-

28、parameter in PBR running. A complete characterization of hydrodynamic conditions is presented, using computational fluids dynamics (CFD). After validation by comparison with experimental measurements, a parametric study is conducted to characterize important hydrodynamics features with respect to PB

29、R application (light access, circulation velocity, global shear-stress), and then to investigate a possible optimization of the process via modification of the impeller used for culture mixing. The final part of the study is devoted to a detailed investigation of mixing performance of the torus PBR,

30、 by numerically predicting dispersion of a passive tracer in various configurations. The high degree of mixing observed shows the great potential of such innovative geometry in the field of photosynthetic microorganisms cultivation, especially for the design of a lab-scale process to conduct experim

31、ents under well-controlled conditions (light and flow) for modeling purpose.Article Outline1. Introduction2. Photobioreactor description3. Hydrodynamics characterization 3.1. Numerical prediction 3.1.1. Mesh consideration3.1.2. Turbulence model, boundary conditions and numerical details3.2. Particle

32、 image velocimetry (PIV) investigation4. Results 4.1. Global characterization of hydrodynamics characteristics of the torus PBR4.2. Detailed investigation of mixing in the torus PBR 4.2.1. Mixing performance of the torus reactor4.3. Investigation of the lateral dispersion5. ConclusionNotationA gener

33、al methodology for hybrid multizonal/CFD models: Part I. Theoretical frameworkMultizonal models have been widely used for modelling the effects of mixing non-idealities in process equipment, presenting a realistic trade-off of computational efficiency and predictive accuracy between simple models ba

34、sed on idealised descriptions of mixing and full computational fluid dynamics (CFD) computations. However, a key weakness of multizonal models has been the difficulty of characterisation of the flow-rates between adjacent zones, and also of fluid mechanical quantities, such as the turbulent energy d

35、issipation rate, that have important effects on the process behaviour within each zone. This paper presents a formal framework for addressing the above difficulties via a multiscale modelling approach based on hybrid multizonal/CFD models. The framework is applicable to systems where the fluid dynam

36、ics operate on a much faster time-scale than other phenomena, and can be described in terms of steady-state CFD computations involving a (pseudo) homogeneous fluid, the physical properties of which are relatively weak functions of intensive properties. Such processes include crystallisation and a wi

37、de variety of liquid-phase chemical and biological reactions.Article OutlineNomenclature1. Introduction 1.1. Hybrid multizonal/CFD models1.2. Objectives and structure of this paper2. A general multizonal model for processing equipment 2.1. Structure of the multizonal model2.2. Characterisation of po

38、rts and interfaces2.3. Mathematical models of internal and environment zones2.4. Overall multizonal model3. The CFD model of processing equipment4. The hybrid multizonal/CFD model 4.1. Topological mapping between the two models4.2. Computational coupling between the two models4.3. Overview of the hy

39、brid model4.4. An illustrative example5. Concluding remarksHydrodynamics of slug flow inside capillariesUnderstanding the motion of long gas bubbles (gas slugs) inside capillaries is a challenging problem that is relevant in many processes of chemical and biological interests. It has been proved by

40、many workers that such long gas bubbles can be used successfully in enhancing mass and heat transfer in many chemical and biological processes. In order to quantify and understand this enhancement a light was shed on the hydrodynamics of such a flow pattern. The volume of fluid method implemented in

41、 the commercial CFD package, Fluent, is used for this numerical study. Velocity and bubble profile were obtained as functions of capillary number. Computed values of the bubble velocity and diameter were in excellent agreement with published experimental measurements. The detailed velocity field aro

42、und the bubble was also computed and compared favourably with those experimental results reported in literature.Article Outline1. Introduction2. Formulation of the problem and the solution strategy 2.1. Governing equations 2.1.1. The continuity equation2.1.2. The momentum equation2.1.3. The volume f

43、raction equation2.1.4. Surface tension2.2. Differencing schemes2.3. Physical properties2.4. Interface tracking2.5. Model geometry3. Results and discussion 3.1. Velocity field and wall shear stress distribution3.2. Bubble shape3.3. Relative velocity (W)3.4. Bubble velocity4. ConclusionNotationComputa

44、tional investigation of fluid dynamics in a recently developed centrifugal impeller bioreactor生物反应器的动态流体特性开发与计算方法的审查和运用Biochemical EngineeringCentrifugal impeller bioreactor (CIB) was recently developed for shear sensitive biological systems. To better understand its fluid velocity profile, liquid c

45、irculation flow, shear stress, and circulation time distribution (CTD), in this study a computational fluid dynamics (CFD) approach was taken to quantitatively assess the effects of major impeller designing and bioreactor operating parameters on those characteristics. Comparison of the simulated vel

46、ocity profiles near the impeller tip with the experimental measurement results was carried out, and a good agreement was demonstrated. Based on the simulated circulation flow through the draft tube, a new empirical correlation of the circulation flow (QL) with respect to the impeller designing and o

47、perating parameters was established. In addition, three distinct circulation cycles were identified and their time distribution was quantified. The above information obtained from the CFD simulation and analysis is helpful to future optimization and scale-up/scale-down of the CIB.Article OutlineNome

48、nclature1. Introduction2. Materials and methods 2.1. Description of centrifugal impeller bioreactor (CIB)2.2. Computational methods2.3. CTD determination3. Results and discussion 3.1. Velocity profiles3.2. Shear stress3.3. Circulation flow3.4. Circulation time distribution4. ConclusionAcknowledgemen

49、tsCharacterization of a flat plate photobioreactor for the production of microalgaeChemical EngineeringThis paper presents the characterization of a flat panel photobioreactor (0.07m wide, 1.5m height and 2.5m length) for the production of microalgae. Several factors are considered. The orientation

50、was studied first resulting east/west the most favourable because the total solar radiation intercepted was maximum, increasing 5% with regard to horizontal placement, and the exposure resulted to be the most homogeneous over the year. Then, gas holdup, mass transfer, mixing and heat transfer were s

51、tudied as a function of the aeration rate. This is a key operating variable because it determines the power supply, which governs the fluid-dynamics of the system and subsequently influences other transport phenomena. The gas holdup and mass transfer coefficient found were consistent with referenced

52、 values for bubble columns observed in tubular photobioreactor. A power supply of 53W/m3 promoted a mass transfer rate high enough to avoid the excessive accumulation of dissolved oxygen in this flat panel photobioreactor. This is similar to the 40W/m3 necessary in bubble columns and much lower than

53、 the 20003000W/m3 required in tubular photobioreactors. However, this power supply is in the order of magnitude of 100W/m3, which has been reported to damage some microalgal cells, whereas no damage has been referenced in tubular photobioreactors. Even at low power supplies the mixing time was short

54、er than 200s, longer than the 60s measured for bubble columns, but quite faster than the typical values found for tubular photobioreactors (110h). With regard to heat transfer, global coefficients were determined for the internal heat exchanger and for the external surface of the photobioreactor. Th

55、e observed behaviour was similar to that referenced for bubble columns, although the values of heat transfer coefficients measured were lower than in bubble columns. The heat transfer coefficient of the internal heat exchanger (over 500W/m2K) was much higher than the coefficient of the external surf

56、ace of the reactor (30W/m2K). Internal heat exchangers are therefore useful to control the temperature of the culture in this type of photobioreactor. The major disadvantage of this reactor is the potential high stress damage associated with aeration. The main advantages are the low power consumptio

57、n (53W/m3) and the high mass transfer capacity (0.0071/s). The characterization carried out allows improving the design and establishing the proper operating conditions for the production of microalgae using this type of photobioreactor.Article OutlineNomenclature1. Introduction2. Materials and meth

58、ods 2.1. Flat panel photobioreactor2.2. Fluid-dynamic and mixing characterization2.3. Heat transfer measurements2.4. Solar radiation3. Results 3.1. Solar radiation3.2. Fluid-dynamics, mass transfer and mixing characterization3.3. Heat transfer measurements4. Discussion 4.1. Solar radiation4.2. Fluid-dynamic, mass transfer and mixing characterization4.3. Heat transfer measurements5. ConclusionsAcknowledgements微藻养殖的设施The optimal design of tw