基于CFD的开式微藻反应器中混合器结构优化
|
摘要
针对跑道池中藻液的混合性能不足,将用于封闭管式微藻反应器的静态混合器引入敞开式跑道池中,基于计算流体力学(CFD)技术对混合器的结构进行设计优化,并引入平均光暗循环周期(T_(av))和单位功耗下光梯度方向上的速度(η)来评价藻液的混合性能.首先通过添加混合器并改变其排列方式研究其对藻液的光梯度方向速度、功耗及光暗循环周期的影响,然后运用正交试验法综合分析了叶片的横纵向排列方式、叶片起始位置及蹼轮转速对两个性能指标的影响.优化后的试验方案:蹼轮转速为11 r/min,叶片组数为3,叶片列数为2,弯道距离为100 mm.在该方案下,藻液的混合性能最佳,T_(av)缩短了59.7%,η增大了35%.
Aiming at the inadequate mixing performance of algae in raceway pond,the static mixer used in closed tubular microalgae reactors was introduced into the open raceway pond.The structure of the mixer was optimized based on computational fluid dynamics(CFD) technology and two indexes were introduced to evaluate the mixing performance of algal fluid,which were average light dark cycle period Tav,and velocity in the light gradient direction per unit power consumption η.First,the influence of the addition of mixers and their arrangements on the velocity in the light gradient direction,power consumption and average light dark cycle period of algal fluid were investigated.Then,the influence of the horizontal and vertical arrangement of mixer blades,starting position of blades and velocity of paddle wheel on the two indexes mentioned above was analyzed comprehensively by using the orthogonal method.When the rotational speed is higher than 11 r/min,the increase of the power consumption of the raceway pond is far greater than that of the mixing performance of the algal fluid.The optimized test scheme is as follows:the rotational speed of the paddle wheel is 11 r/min,the number of the mixer blades in horizontal direction is 3,the number of the mixer blades in vertical direction is 2,and the distance from the bend is 100 mm.Under this scheme,the algae mixture performance is the best,that is Tav is reduced by59.7% and η is increased by 35%.
Aiming at the inadequate mixing performance of algae in raceway pond,the static mixer used in closed tubular microalgae reactors was introduced into the open raceway pond.The structure of the mixer was optimized based on computational fluid dynamics(CFD) technology and two indexes were introduced to evaluate the mixing performance of algal fluid,which were average light dark cycle period Tav,and velocity in the light gradient direction per unit power consumption η.First,the influence of the addition of mixers and their arrangements on the velocity in the light gradient direction,power consumption and average light dark cycle period of algal fluid were investigated.Then,the influence of the horizontal and vertical arrangement of mixer blades,starting position of blades and velocity of paddle wheel on the two indexes mentioned above was analyzed comprehensively by using the orthogonal method.When the rotational speed is higher than 11 r/min,the increase of the power consumption of the raceway pond is far greater than that of the mixing performance of the algal fluid.The optimized test scheme is as follows:the rotational speed of the paddle wheel is 11 r/min,the number of the mixer blades in horizontal direction is 3,the number of the mixer blades in vertical direction is 2,and the distance from the bend is 100 mm.Under this scheme,the algae mixture performance is the best,that is Tav is reduced by59.7% and η is increased by 35%.
引文
[1]刘娟妮,胡萍,姚领,等.微藻培养中光生物反应器的研究进展[J].食品科学,2006,27(12):772-777.
[2]刘永平.海藻生物燃料产业化开发的进展[J].中外能源,2009,14(9):31-38.
[3]CHENG J,YANG Z,YE Q,et al.Enhanced flashing light effect with up-down chute baffles to improve microalgal growth in a raceway pond[J].Bioresource Technology,2015,190:29-35.
[4]POSTEN C.Design principles of photo-bioreactors for cultivation of microalgae[J].Engineering in Life Sciences,2009,9(3):165-177.
[5]YANG Z,CHENG J,YE Q,et al.Decrease in light/dark cycle of microalgal cells with computational fluid dynamics simulation to improve microalgal growth in a raceway pond[J].Bioresour Technol,2016,220:352-359.
[6]ZENG F,HUANG J,MENG C,et al.Investigation on novel raceway pond with inclined paddle wheels through simulation and microalgae culture experiments[J].Biopr-ocess Biosyst Eng,2016,39(1):169-180.
[7]HADIYANTO H,ELMORE S,van GERVEN T,et al.Hydrodynamic evaluations in high rate algae pond(HRAP)design[J].Chemical Engineering Journal,2013,217:231-239.
[8]ALI H,CHEEMA T A,YOON H S,et al.Numerical prediction of algae cell mixing feature in raceway ponds using particle tracing methods[J].Biotechnology&Bioengineering,2015,112(2):297-307.
[9]JAWORSKI Z,PIANKO-OPRYCH P,MARCHISIO D L,et al.CFD modelling of turbulent drop breakage in a kenics static mixer and comparison with experimental data[J].Chemical Engineering Research and Design,2007,85(5):753-759.
[10]CHENG W,HUANG J,CHEN J.Computational fluid dynamics simulation of mixing characteristics and light regime in tubular photobioreactors with novel static mixers[J].Journal of Chemical Technology&Biotechnology,2016,91(2):327-335.
[11]PERNER-NOCHTA I,POSTEN C.Simulations of light intensity variation in photobioreactors[J].Journal of Biotechnology,2007,131(3):276.
[12]刘瑞江,张业旺,闻崇炜,等.正交试验设计和分析方法研究[J].实验技术与管理,2010,27(9):52-55.
[13]林博,吴晶.叶片结构对跑道池式光生物反应器功耗及混合性能影响的数值模拟[J].生物产业技术,2017(2):94-101.
[14]PRUVOST J,POTTIER L,LEGRAND J.Numerical investigation of hydrodynamic and mixing conditions in a torus photobioreactor[J].Chemical Engineering Science,2006,61(14):4476-4489.
[15]YUN YS,PARK J.Attenuation of monochromatic and polychromatic lights in Chlorella vulgaris suspensions[J].Applied Microbiology and Biotechnology,2001,55(6):765-770.
[2]刘永平.海藻生物燃料产业化开发的进展[J].中外能源,2009,14(9):31-38.
[3]CHENG J,YANG Z,YE Q,et al.Enhanced flashing light effect with up-down chute baffles to improve microalgal growth in a raceway pond[J].Bioresource Technology,2015,190:29-35.
[4]POSTEN C.Design principles of photo-bioreactors for cultivation of microalgae[J].Engineering in Life Sciences,2009,9(3):165-177.
[5]YANG Z,CHENG J,YE Q,et al.Decrease in light/dark cycle of microalgal cells with computational fluid dynamics simulation to improve microalgal growth in a raceway pond[J].Bioresour Technol,2016,220:352-359.
[6]ZENG F,HUANG J,MENG C,et al.Investigation on novel raceway pond with inclined paddle wheels through simulation and microalgae culture experiments[J].Biopr-ocess Biosyst Eng,2016,39(1):169-180.
[7]HADIYANTO H,ELMORE S,van GERVEN T,et al.Hydrodynamic evaluations in high rate algae pond(HRAP)design[J].Chemical Engineering Journal,2013,217:231-239.
[8]ALI H,CHEEMA T A,YOON H S,et al.Numerical prediction of algae cell mixing feature in raceway ponds using particle tracing methods[J].Biotechnology&Bioengineering,2015,112(2):297-307.
[9]JAWORSKI Z,PIANKO-OPRYCH P,MARCHISIO D L,et al.CFD modelling of turbulent drop breakage in a kenics static mixer and comparison with experimental data[J].Chemical Engineering Research and Design,2007,85(5):753-759.
[10]CHENG W,HUANG J,CHEN J.Computational fluid dynamics simulation of mixing characteristics and light regime in tubular photobioreactors with novel static mixers[J].Journal of Chemical Technology&Biotechnology,2016,91(2):327-335.
[11]PERNER-NOCHTA I,POSTEN C.Simulations of light intensity variation in photobioreactors[J].Journal of Biotechnology,2007,131(3):276.
[12]刘瑞江,张业旺,闻崇炜,等.正交试验设计和分析方法研究[J].实验技术与管理,2010,27(9):52-55.
[13]林博,吴晶.叶片结构对跑道池式光生物反应器功耗及混合性能影响的数值模拟[J].生物产业技术,2017(2):94-101.
[14]PRUVOST J,POTTIER L,LEGRAND J.Numerical investigation of hydrodynamic and mixing conditions in a torus photobioreactor[J].Chemical Engineering Science,2006,61(14):4476-4489.
[15]YUN YS,PARK J.Attenuation of monochromatic and polychromatic lights in Chlorella vulgaris suspensions[J].Applied Microbiology and Biotechnology,2001,55(6):765-770.