套管式新型光生物反应器的性能初步实验

针对管式光生物反应器藻液中溶解氧及pH限制进一步规模扩大等因素,设计了一种套管新型内曝气式光生物反应器。以Chlorella vulgaris为培养对象,BG-11为培养基,以细胞干重为检测指标,同时检测藻液的溶氧量和pH,比较了小规模实验条件(锥形瓶,500 mL)和套管式新型光生物反应器(36 L)对微藻生物质积累的影响。结果表明,新型反应器和小规模实验条件相比,培养体积扩大了72倍,培养10 d时微藻的比生长率下降了33.2%,单位体积产率下降了69.8%。在整个培养过程中,藻液溶氧量为6.2～7.0 mg/L,未超过限值7.5 mg/L。通入气体为空气,藻液pH由7.5上升至9.0,处于微藻可适应范围(4.5～10.6),尚可通过在空气中混入CO2进行调节。     

光生物反应器微藻生长与比消光系数的关系

研究了两种微藻液消光系数的波长分布特征。经分析发现,色素吸收消光占总消光的比例各个波长下均小于１／４。藻体颗粒大小是藻液比消光系数的重要决定因素。利用这一特性可以监测单细胞藻的同步生长。文中指出：当入射光强相同,且在相同几何尺寸的光生物反应器中培养微藻,藻体半径越大,藻液的比消光系数越小藻液的平均光强越高。     

盐藻在气升式光生物反应器中的光自养培养

在气升式光生物反应器中进行了盐藻培养特性的研究，确定了盐藻在2.5 L气升式光生物反应器中培养的适宜条件为：温度30℃，光强1.6 mW/cm2，盐浓度16%，通气量20 ml/min. 扩大到20 L反应器培养盐藻生长良好. 采用气升式光反应器培养盐藻生长快，周期短，4~7 d后即可进入稳定期；最终细胞密度大，最大为1.6?106 cells/ml；藻液中胡萝卜素含量高，最高含量32 mg/L.实验表明气升式光生物反应器适合于盐藻的培养.     

微藻培养的光生物反应器

微藻能有效利用光能、ＣＯ2 和无机盐类合成蛋白质、脂肪、碳水化合物以及多种高附加值生物活性物质 ,可以培养微藻来生产健康食品、食品添加剂、动物饲料、生物肥料及其他天然产品。另外 ,近年来分子遗传学和基因工程研究证实 ,大肠杆菌的载体和启动因子往往可以适用于蓝藻 ,尤其是单细胞蓝藻的转基因 ,这使得蓝藻基因工程得到了较快的发展 ,利用藻类为宿主的基因产物的生产也日益受到关注 ,因此微藻的培养受到广泛重视。微藻的生长方式决定光照在反应器中的重要性。除了一些能完全自养的微藻培养可以在无光照条件下进行[1](此时反应器可以…     

微藻光生物反应器应用研究

选择三种海洋微型藻,叉鞭金藻、扁藻和塔玛亚历山大藻,在自行研制的光生物反应器中进行人工培育繁殖,采用不同光照强度和搅拌速度,测试光生物反应器应用于海洋微藻人工培育的效果。研究结果表明:这三种海洋微型藻在研制的生物反应器中细胞均能快速分裂增长,细胞增殖的浓度比在自然条件培养的同种藻的细胞增殖浓度要高1-2倍。并验证该光生物反应器的光照强度和搅拌强度可以根据微藻实际生长需要而调整到最佳状态,扁藻、叉鞭金藻、塔玛亚历山大藻分别在光照强度10000Lx±300Lx、5000Lx±300Lx、3000Lx±300Lx时生长最好。高转速和连续搅拌不利于塔玛亚历山大藻细胞增殖,增殖慢、藻浓度不高。     

用于微藻培养的气升式光生物反应器

基于微藻光自养培养特性 ,构建了具有较大面积体积比的 15 L内外光源相结合的气升式光生物反应器 ,考察了两种不同形态藻细胞培养体系中 ,光强随细胞浓度及光程距离衰减的规律 ,得到了描述光衰减的数学关系式 ,即在鱼腥藻 712 0培养体系中为 I=I0 exp[- (0 .0 131+0 .987OD750 )·L],在聚球藻 70 0 2培养体系中为 I=I0 exp[- (- 0 .0 2 39+0 .0 777OD750 )·L],并据此对培养过程中光强沿反应器径向的动态分布情况进行了估算。在该反应器中进行了鱼腥藻 712 0和聚球藻 70 0 2两种蓝藻的光自养培养 ,藻细胞培养终密度分别达到 1.5 3g/ L和 3.4g/ L ,体积产率分别为 0 .31g L-1d-1和 0 .5 7g L-1d-1,说明该反应器适合于微藻的高密度培养     

紫球藻的光生物反应器培养

利用光生物反应器就碳源及其供给形式、光强和反应器的操作条件等影响紫球藻生长的因素进行了研究.结果表明:反应器良好的液体循环速度有助于培养液中每个细胞对光能的吸收利用,使紫球藻细胞可以获得较大的生长速度;利用CO2为碳源可以获得比利用NaHCO3更大的生长速度,有效地提高了紫球藻的生物量产量.在本实验条件下,细胞的生长速度和生物量产率分别达到了0.952 d-1和42.31 g/(m2.d).     

波形隔板对平板式生物反应器传质及混合性能的影响

对带波纹隔板的平板式生物反应器,利用计算流体动力学进行流场模拟,验证模型可靠性后,系统分析波纹隔板高/波长(L/l)和波幅/波长(A/l)两个波纹隔板结构参数对反应器传质及流动混合特性的影响. 结果表明,当L/l=12时,传质及流动混合性能较好,液相体积传质系数(kLa)、平均湍动能(Em)、下降区停留时间占循环一周时间之比(q)等表征传质及混合的参数值均较大,得到的液体流速在微藻生长的最佳流速附近. 当A/l=0.8时,反应器的传质性能最优,kLa比采用平直隔板时增加了约10%;当A/l=0.4时,反应器的混合效果最佳,Em比采用平直隔板时增加14.7%.     

光生物反应器对工业锅炉烟道尾气中二氧化碳的利用

比较了工业化光生物反应器培养微藻的3种主要CO2利用方式,阐述了工业锅炉烟道尾气所含多种重金属元素会在藻液中形成重金属离子,微藻在吸收CO2的同时也吸附重金属离子的机理.指出当重金属离子在藻液中积累到一定浓度时会造成光生物反应器的微藻生长系统崩溃,不能直接采用工业锅炉烟道尾气作为工业化封闭式光生物反应器培养微藻系统的碳源供给方式.     

海洋微藻培养及光生物反应器的研究进展

概述微藻的特点及国内外应用现状,重点讨论培养微藻的条件及不同类型光生物反应器的特点。     

Experimental and Numerical Studies of the Flow Field in a Stirred Tank Equipped with Multiple Side‐Entering Agitators

The flow field and the macro‐mixing process in a stirred tank equipped with four side‐entering agitators were investigated experimentally and numerically. Experiments were conducted using two‐dimensional particle image velocimetry (PIV) measurements to characterize the flow field at different positions in the vessel. The computational fluid dynamics (CFD) simulation was performed by the software Fluent 6.3, using the standard k‐ϵ turbulent model and the multiple reference frame together with the sliding mesh technique. The macro‐mixing process was also discussed using CFD and decolorization experiments. The effects of the tracer detection positions and some mounting parameters in the mixing system were discussed. The results show that the mixing process was dominated by the flow field pattern in the stirred tank. According to the mixing times under different conditions using CFD simulation, the mounting parameters including inclination angle, plunging length and mounting height of the shaft were optimized.     

Experimental and Numerical Investigation of a Novel Spiral Micromixer with Sinusoidal Channel Walls

A novel spiral micromixer with sinusoidal channel walls was designed to enhance the mixing index in the low to intermediate Reynolds number range (1 < Re < 100). To analyze the fluid flow, a set of numerical simulations were performed using the finite-difference method. The microchip was fabricated from polydimethylsiloxane, employing the soft-lithography technique. The degree of mixing was increased by 99.11 % when using the proposed micromixer, compared to 59.44 % for a simple spiral micromixer. The introduced microchannel drastically reduced the mixing length, increasing the mixing index of a 0.5-loop spiral-sinusoidal microchannel compared to that of the simple spiral microchannel with 1.5 loops. The mixing index of the 3-loop mixer was higher than that of the microchannel with 1.5 loops, and its pressure drop was increased.     

Impact of thixotropy on flow patterns induced in a stirred tank: Numerical and experimental studies

Agitation of a thixotropic shear-thinning fluid exhibiting a yield stress is investigated both experimentally and via simulations. Steady-state experiments are conducted at three impeller rotation rates (1, 2 and 8 s⁻¹) for a tank stirred with an axial-impeller and flow-field measurements are made using particle image velocimetry (PIV) measurements. Three-dimensional numerical simulations are also performed using the commercial CFD code ANSYS CFX10.0. The viscosity of the suspension is determined experimentally and is modelled using two shear-dependant laws, one of which takes into account the flow instabilities of such fluids at low shear rates. At the highest impeller speed, the flow exhibits the familiar outward pumping action associated with axial-flow impellers. However, as the impeller speed decreases, a cavern is formed around the impeller, the flow generated in the vicinity of the agitator reorganizes and its pumping capacity vanishes. An unusual flow pattern, where the radial velocity dominates, is observed experimentally at the lowest stirring speed. It is found to result from wall slip effects. Using blades with rough surfaces prevents this peculiar behaviour and mainly resolves the discrepancies between the experimental and computational results.     

三叶后掠-HEDT组合桨搅拌釜内流场的模拟及实验

对应用于聚乙烯聚合反应中的三叶后掠-HEDT组合桨的搅拌釜内流场进行了模拟研究,分析组合桨的离底距C ₁、桨间距C ₂以及转速N的变化对搅拌釜内流场的影响,利用PIV实验对模拟结果进行了验证;将该组合桨与三叶后掠-六直叶圆盘涡轮组合桨进行了模拟对比研究。结果表明：当桨间距与釜内径的比为0.35时,釜内桨叶间的流体流动效果最好,该条件下能够改善搅拌釜上层流体的速度分布;当离底距与釜内径的比值为0.29时,组合桨下方出现了整体的环流,有利于釜底流体的混合;桨叶转速N=90 r/min时釜内流体速度分布均匀,同时上层HEDT桨叶产生的射流方向趋于水平。两种组合桨的对比研究表明：二者流型相近,但前者搅拌功率能够得到明显降低。研究结果可为三叶后掠-HEDT组合桨在聚乙烯聚合反应釜中的工程应用提供参考。     

多层新型桨搅拌槽内气-液两相流动的实验与数值模拟

对三层新型组合桨气-液两相搅拌槽内的流体流动进行了实验研究,并采用计算流体力学(CFD)的方法对气-液两相搅拌槽的通气搅拌功率、流场、局部气含率及总体气含率进行了数值模拟,数值模拟采用了欧拉-欧拉方法,数值模拟结果与实验值吻合良好,同时考察了通气流量和搅拌转速对通气搅拌功率和气含率的影响规律. 研究结果表明,欧拉-欧拉方法能较好地模拟搅拌槽内气-液两相流的流动状况.     

改进型Ross静态混合器牛顿流体流动的实验与数值模拟

在改进型Ross静态混合器中对牛顿流体的流动进行了实验研究,并对空管和5单元的改进型Ross静态混合器的流动进行了数值模拟,将实验与数值模拟结果进行了比较,证实二者的结果一致. 结果表明,在改进型Ross静态混合器中,牛顿流体流动的压力降与雷诺数和静态混合器长径比的关系为Dp=14.7231Re-0.156(L/D)0.446ru2/2;在Re=20000时,z因子有最大值;整个静态混合器的压力降(流动阻力)主要集中在混合单元区域.     

Study on flow fields in a bioreactor with perforated blades

Flow fields of a gas–liquid fluid in a bioreactor with perforated blades were evaluated with the computational fluid dynamics and particle image velocimetry (PIV). The flow pattern of the fluid was the complex turbulence, and the fluid had preferable flow fields for fermentations. Using a rotating coordinate system and a sliding mesh method, a mesh of 24 × 16 × 80 (X × Y × Z) was selected due to its high accuracy and appropriate workload. The numerical results of the two‐phase flow model agreed well with the experimental results of the PIV, such as flow field characteristics and data curves. The RNG k–ε model was adopted, which could precisely simulate anisotropic flow fields around higher‐speed blades. Whole deviations of X‐, Y‐ and Z‐direction velocities ranged only from 5.4% to 10.5%, and continuous turbulence models could effectively simulate transfer procedures of the fluid. Because of its low cost, simplicity and easy of scale‐up, the bioreactor with perforated blades and its models mechanism of fluid microelements are expected to be efficient for its industrial amplification and application in food industry. © 2012 Canadian Society for Chemical Engineering     

CFD-PIV流场分析技术应用于太阳热水系统的研究进展

综述了CFD-PIV技术应用于太阳热水系统的研究进展,重点阐述了该技术用于提高太阳热水系统热效率的优越性,说明了太阳热水系统是应用最广泛的可再生能源利用技术之一。分析系统内的流体流动状况对于强化太阳热水系统中的对流传热过程、优化系统结构、提高系统热效率,进而指导太阳热水系统的工程设计具有非常重要的意义。利用计算流体力学和粒子图像测速技术相结合来分析流场是化学工程相关研究的发展趋势。     

机油滤纸过滤阻力的实验与模拟研究

模拟分析滤纸过滤阻力与各影响因素的关系。根据模拟需要,对不同种常见机油滤纸进行了孔隙率、厚度、过滤阻力、含尘浓度和过滤速度等测试;并依据实验数据,分析得到了滤纸模拟模型,模拟边界条件。通过模拟得到了各影响因素变化时,滤纸过滤阻力随之变化的趋势,给出了滤纸过滤性能的模拟与实验对比结果,验证了模拟方法的可靠性,最后回归分析得到滤纸压降与含尘浓度、过滤速度及孔隙率的关系,为滤纸的优化选择及设计提供参考依据。