Model Validation for Photosynthetically Active Radiation Transport and Multiphase Flow in Algal Photobioreactors

藻类光生物反应器中光合有效辐射传输和多相流的模型验证

• 批准号: 1236676
• 负责人: Richard Vigil
• 金额: $ 35万
• 依托单位: Iowa State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1236676&HistoricalAwards=false
• 关键词: Model; Validation; Photosynthetically; Active; Radiation

CBET-1236676VigilRecent interest in algaculture is largely driven by the desire to acquire renewable alternatives for petroleum-based products. However, the development of commercially-viable algal biorefineries requires significant advancements not only in the bioengineering of robust, fast-growing microorganisms tuned to produce high-value products, but also substantial improvements in process engineering for more rapid and efficient production of algal products. Breakthroughs in the design and optimization of algal photobioreactors can be achieved through the implementation of highly accurate and computationally efficient numerical models of radiation transport and complex multiphase fluid phenomena that characterize these reactors. This research project directly addresses the need to develop reliable computational models capable of being used for the design and scale-up of algal photobioreactors. In particular, state-of-the-art two-phase computational fluid dynamics simulations of buoyancy-driven bubbly flows commonly found in photobioreactors will be validated by using index-of-refraction matching methods to carry out particle image velocimetry experiments with sufficient temporal and spatial resolution to rigorously test simulation predictions and to determine the importance of including various interface force models for drag, lift, virtual mass, rotation, and strain. The three-dimensional distribution of light in algal photobioreactors will be simulated by developing a novel spectral radiation transport model (based upon the method of discrete ordinates) that also accounts for the presence of bubbles and the optical effects of transparent reactor walls. Validation of the spectral radiation transport model will be achieved by carrying out a series of light measurements in a cylindrical algal bioreactor illuminated by filtered light sources that pass radiation with narrow bands of wavelengths in the photosynthetically active regime. After the computational fluid dynamics and radiation transport simulations have been validated, the interplay between the fluid dynamics and the radiation transport in the reactor will be explored by carrying out Lagrangian particle tracking simulations to compute light absorption histories experienced by individual algal cells, which is of paramount importance in determining the rate of production of biomass by these microorganisms. Algaculture is an increasingly attractive alternative for producing fuels and chemicals derived from petroleum, but the development of economically viable algal biorefineries requires significant improvements in both the engineering of elite microorganisms and in the design and scaleup of photobioreactors. This project will employ experimental methods and computer simulations to improve the understanding of how fluid motion and light distribution in algal photobioreactors impacts the production of biomass, and the results will form the basis for constructing a simulation tool for improving the design of production-scale equipment used in algaculture. The research will also provide educational opportunities for graduate and undergraduate students in a research area of strategic national importance.

最近人们对海藻养殖的兴趣很大程度上是由于人们希望获得石油基产品的可再生替代品。然而，商业上可行的藻类生物精炼厂的发展不仅需要在健壮、快速生长的微生物生产高价值产品的生物工程方面取得重大进展，而且还需要在工艺工程方面进行实质性改进，以更快、更有效地生产藻类产品。藻类光生物反应器的设计和优化方面的突破可以通过实现高精度和计算效率高的辐射传输和复杂多相流体现象的数值模型来实现，这些模型是这些反应器的特征。该研究项目直接解决了开发可靠的计算模型的需求，这些模型能够用于藻类光生物反应器的设计和放大。特别是，在光生物反应器中常见的浮力驱动气泡流的最先进的两相计算流体动力学模拟将通过使用折射率匹配方法进行粒子图像测速实验来验证，该实验具有足够的时间和空间分辨率，以严格测试模拟预测，并确定包括各种界面力模型的重要性阻力，升力，虚拟质量，旋转和应变。光在藻类光生物反应器中的三维分布将通过开发一种新的光谱辐射传输模型（基于离散坐标方法）来模拟，该模型也考虑了气泡的存在和透明反应器壁的光学效应。光谱辐射传输模型的验证将通过在一个圆柱形藻类生物反应器中进行一系列的光测量来实现，该反应器由滤光光源照射，滤光光源在光合作用活跃状态下通过具有窄波段波长的辐射。在计算流体动力学和辐射输运模拟得到验证后，将通过拉格朗日粒子跟踪模拟来研究反应器中流体动力学和辐射输运之间的相互作用，以计算单个藻类细胞经历的光吸收历史，这对于确定这些微生物的生物量生产速度至关重要。藻类养殖是生产石油衍生燃料和化学品的一种越来越有吸引力的替代方法，但经济上可行的藻类生物精炼厂的发展需要在精英微生物的工程和光生物反应器的设计和规模上进行重大改进。本项目将采用实验方法和计算机模拟来提高对藻类光生物反应器中流体运动和光分布如何影响生物量生产的理解，并将为构建模拟工具以改进用于藻类养殖的生产规模设备的设计奠定基础。该研究还将为研究生和本科生提供具有国家战略重要性的研究领域的教育机会。