Advances in the use of CFD to characterize, design and optimize bioenergy systems

This article is a critical review of the state-of-the-art of computational fluid dynamics (CFD) used to investigate bioreactors that produce biomethane and biohydrogen by means of biochemical conversion technology. First, the issue on rheology of biomaterials is addressed. Second, the CFD development in six major bioreactors is documented. The bioreactors studied are: (1) anaerobic lagoon, (2) plug-flow digester, (3) complete-mix digester, (4) anaerobic biohydrogen fermenter, (5) anaerobic biofilm reactor, and (6) photobioreactor. Third, the CFD simulation strategy that includes pre-processing and solver as well as post-processing is summarized. Fourth, opportunities and challenges for CFD applications in bio-energy are presented. Finally, specific comments and suggestions are made on: rheology, heat transfer, mass transfer, light transfer, turbulence, and multiphase flow. The primary goal of CFD research in biorenewable energy to develop a comprehensive model that integrates physical and biological processes is highlighted. (C) 2012 Elsevier B.V. All rights reserved.